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25 pages, 1747 KiB  
Article
Life Cycle Assessment (LCA) of the Impact on the Environment of a Cosmetic Cream with Gold Nanoparticles and Hydroxylated Fullerene Ingredients
by Rebeka Rudolf, Peter Majerič, Zorka Novak Pintarič, Andrej Horvat and Damjan Krajnc
Appl. Sci. 2024, 14(24), 11625; https://doi.org/10.3390/app142411625 - 12 Dec 2024
Viewed by 631
Abstract
This review provides a comprehensive Life Cycle Assessment (LCA) of a cosmetic cream to assess the environmental impacts throughout its entire life cycle, from raw material extraction to disposal, using the methodology according to international standards. The LCA was performed using the OpenLCA [...] Read more.
This review provides a comprehensive Life Cycle Assessment (LCA) of a cosmetic cream to assess the environmental impacts throughout its entire life cycle, from raw material extraction to disposal, using the methodology according to international standards. The LCA was performed using the OpenLCA 2.0.1 software, with data from the Ecoinvent 3.8 database and relevant literature. The assessment focused on multiple impact categories, including climate change, acidification, eutrophication (freshwater, marine and terrestrial), ecotoxicity (freshwater), human toxicity (cancer and non-cancer), ionizing radiation, land use, ozone depletion, photochemical ozone formation, resource use (fossils, minerals and metals), and water use. The LCA of a cosmetic cream containing gold nanoparticles revealed significant environmental impacts across critical categories. The total climate change potential was 2596.95 kg CO2 eq., driven primarily by nanoparticle synthesis (60.7%) and electricity use (31.9%). Eutrophication of freshwater had the highest normalized result (3.000), with nanoparticle synthesis contributing heavily, indicating the need for improved wastewater treatment. The resource use (minerals and metals) scored 1.856, while the freshwater ecotoxicity reached 80,317.23 CTUe, both driven by the nanoparticle production. The human toxicity potentials were 1.39 × 10−6 CTUh (cancer) and 7.45 × 10−5 CTUh (non-cancer), linked to emissions from synthesis and energy use. The LCA of the cosmetic cream revealed several critical areas of environmental impact. The most significant impacts are associated with gold nanoparticle synthesis and electricity use. Addressing these impacts through optimized synthesis processes, improved energy efficiency, and alternative materials can enhance the product’s sustainability profile significantly. Full article
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Figure 1
<p>System boundaries of the cosmetic cream production life cycle.</p>
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<p>Normalized environmental impact assessment results.</p>
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<p>Most significant contributing processes to the environmental footprint of cosmetic cream.</p>
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<p>Single score results of the environmental impact assessment (values in points, Pt).</p>
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13 pages, 3604 KiB  
Article
Enhancing the Efficacy of Radiation Therapy by Photochemical Internalization of Fibrin-Hydrogel-Delivered Bleomycin
by Sophia Renee Laurel, Keya Gupta, Jane Nguyen, Akhil Chandekar, Justin Le, Kristian Berg and Henry Hirschberg
Cancers 2024, 16(23), 4029; https://doi.org/10.3390/cancers16234029 - 30 Nov 2024
Viewed by 724
Abstract
Background/Objectives: Although the use of radiation-sensitizing agents has been shown to enhance the effect of radiation on tumor cells, the blood–brain barrier (BBB) impedes these agents from reaching brain tumor sites when provided systemically. Localized methods of sensitizer delivery, utilizing hydrogels, have the [...] Read more.
Background/Objectives: Although the use of radiation-sensitizing agents has been shown to enhance the effect of radiation on tumor cells, the blood–brain barrier (BBB) impedes these agents from reaching brain tumor sites when provided systemically. Localized methods of sensitizer delivery, utilizing hydrogels, have the potential to bypass the blood–brain barrier. This study examined the ability of photochemical internalization (PCI) of hydrogel-released bleomycin to enhance the growth-inhibiting effects of radiation on multi-cell glioma spheroids in vitro. Methods: Loaded fibrin hydrogel layers were created by combining thrombin, fibrinogen, and bleomycin (BLM). Supernatants from these layers were collected, combined with photosensitizer, and added to F98 glioma spheroid cultures. Following light (PCI) and radiation treatment, at increasing dosages, spheroid growth was monitored for 14 days. Results: PCI of released BLM significantly reduced the radiation dose required to achieve equivalent efficacy compared to radiation or BLM + RT alone. Both immediate and delayed RT delivery post-BLM-PCI resulted in similar degrees of growth inhibition. Conclusions: Non-degraded BLM was released from the fibrin hydrogel. PCI of BLM synergistically increased the growth-inhibiting effects of radiation treatment compared to radiation and BLM, as well as radiation acting as a single treatment. Full article
(This article belongs to the Special Issue Novel Targeted Therapies in Brain Tumors)
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Figure 1

Figure 1
<p>Experimental protocol. Supernatants harvested from BLM-loaded FG or non-loaded fibrin glue coated in media at varying time intervals were transferred to spheroid cultures in multi-well plates. Five experimental arms: non-treatment controls, <b>(2)</b> RT only, <b>(3)</b> BLM<sup>FG</sup> +RT, <b>(4)</b> BLM<sup>FG</sup> (supernatant harvested from BLM-loaded FG), <b>(5)</b> BLM<sup>FG</sup> +PCI + RT.</p>
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<p>(<b>a</b>) RT effect on growth of F98 and BT<sub>4</sub>C spheroids over a range of radiation doses, 0–20 Gy. (<b>b</b>) Effect of BLM-PCI at varying BLM concentrations on F98 and BT<sub>4</sub>C spheroid growth. Data points are the average volumes of spheroids after 14 days in culture, represented as a % of the non-treatment control spheroid volumes. Error bars indicate standard deviation, and * represents significant differences (<span class="html-italic">p</span> &lt; 0.05) when compared to controls.</p>
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<p>(<b>a</b>) Kinetics of the F98 spheroid growth pattern after exposure to RT of 8 Gy. (<b>b</b>) Kinetics of the BT<sub>4</sub>C spheroid growth pattern after exposure to RT of 8 Gy. Spheroids were treated with BLM at 0.3 or 0.6 μg/mL, combined with AlPcS<sub>2a</sub> at 0.06 μg/mL, and light, 0.96 J/cm<sup>2</sup>. Data points are the average spheroid volumes after 14 days in culture, from 2 independent experiments, represented as a % of the non-treatment controls. Error bars indicate standard deviation.</p>
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<p>(<b>a</b>) The effect of varying dilutions of BLM<sup>FG</sup>-PCI on the growth kinetics of the F98 spheroid growth pattern combined with RT of 8 Gy. (<b>b</b>) Kinetics of the BT<sub>4</sub>C spheroid growth pattern after varying dilutions of BLM<sup>FG</sup>-PCI combined with RT of 8 Gy. Spheroids were treated with BLM<sup>FG</sup>, combined with AlPcS<sub>2a</sub> at 0.06 μg/mL and light. Data points are the average volumes of spheroids from 3 independent experiments after 14 days in culture, represented as a % of the non-treatment control spheroid volumes. Error bars indicate standard deviation.</p>
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<p>(<b>a</b>) Effect of increased concentration of BLM loading in FG, with 0–2.4 ug/mL on F98 spheroids that received no RT or received 8 Gy of RT. (<b>b</b>) BT<sub>4</sub>C spheroids with increasing concentration of FG-released BLM and given no RT or 8 Gy of RT. The average volumes of F98 spheroids after 14 days in culture, represented as a % of the non-treatment control spheroid volumes. Error bars indicate standard deviation, and * represents significant differences (<span class="html-italic">p</span> &lt; 0.05) when compared to controls.</p>
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<p>(<b>a</b>) Effects of varying RT doses with and without BLM-PCI on F98 spheroids, 0–15 Gy. (<b>b</b>) Effects of light radiance levels from BLM-PCI with and without RT, 0–1.68 J/cm<sup>2</sup>. The average volumes of F98 spheroids after 14 days in culture, represented as a % of the non-treatment control spheroid volumes. Error bars indicate standard deviation.</p>
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<p>Effects of delay between BLM<sup>FG</sup>-PCI and RT. Spheroids received RT immediately after BLM<sup>FG</sup>-PCI or 24 h post-BLM<sup>FG</sup>-PCI. Data points represent the average volumes of spheroids after 14 days in culture, represented as a % of the non-treatment control spheroid volumes. Error bars indicate standard deviation, and * represents significant differences (<span class="html-italic">p</span> &lt; 0.05) when compared to the controls.</p>
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<p>Light and RT administration to residual tumor cells in a tumor resection cavity. (<b>a</b>) Residual tumor cells in a tumor resection cavity. (<b>b</b>) Resection cavity implanted with FG loaded with BLM/photosensitizer. (<b>c</b>) BLM/photosensitizer released from FG diffuses into tumor sites. (<b>d</b>) Administration of RT by external beam and light by an implanted fiberoptic catheter in the tumor resection cavity.</p>
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15 pages, 5095 KiB  
Article
Temperature Dependence and the Effects of Ultraviolet Radiation on the Ultrastructure and Photosynthetic Activity of Carpospores in Sub-Antarctic Red Alga Iridaea cordata (Turner) Bory 1826
by Nelso P. Navarro, Pirjo Huovinen, Jocelyn Jofre and Iván Gómez
Plants 2024, 13(18), 2547; https://doi.org/10.3390/plants13182547 - 11 Sep 2024
Viewed by 652
Abstract
The short-term effects of UV radiation and low temperature on ultrastructure, photosynthetic activity (measured as the maximal photochemical quantum yield of photosystem II: Fv/Fm), chlorophyll-a (Chl-a) contents, and UV-absorbing compounds on the carpospores of Iridaea cordata from [...] Read more.
The short-term effects of UV radiation and low temperature on ultrastructure, photosynthetic activity (measured as the maximal photochemical quantum yield of photosystem II: Fv/Fm), chlorophyll-a (Chl-a) contents, and UV-absorbing compounds on the carpospores of Iridaea cordata from a sub-Antarctic population were investigated. Exposure to both photosynthetically active radiation (PAR) and PAR + UV for 4 h caused ultrastructural modifications in all treatments. Under PAR + UV at 2 °C, a disruption of the chloroplast’s internal organization was observed. Plastoglobuli were often found in carpospores exposed to 2 °C. ‘Electron dense particles’, resembling physodes of brown algae, were detected for the first time in cells exposed to PAR and PAR + UV at 8 °C. Fv/Fm decreased following 4 h exposure at 2 °C under PAR + UV (64%) and PAR (25%). At 8 °C, Fv/Fm declined by 21% only under PAR + UV. The photosynthesis of carpospores previously treated with UV partially recovered after a 4 h exposure under dim light. UV-absorbing compounds were degraded in all radiation and temperature treatments without recovery after a 4 h dim light period. Chl-a did not change, whereas total carotenoids increased under PAR at 8 °C The study indicates that although carpospores of I. cordata exhibit photoprotective mechanisms, UV radiation strongly damages their ultrastructure and physiology, which were exacerbated under low temperatures. Full article
(This article belongs to the Special Issue Advances in Algal Photosynthesis and Phytochemistry)
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Figure 1

Figure 1
<p>Structure of <span class="html-italic">Iridaea cordata</span> carpospores. (<b>A</b>) Carpospores under light microscopy and their respective ultrastructural models. (<b>B</b>–<b>E</b>) Transmission electron microscopy (TEM) of carpospores cultivated under control conditions. (<b>B</b>) Carpospores exhibit homogeneously distributed vacuolar spaces, starch grains in the cytoplasm, and a condensed nucleolus. (<b>C</b>,<b>D</b>) Thick cell walls (black arrowheads) and cored vesicles releasing their contents out of the plasmalemma; additionally, tubular invaginations (white arrowheads in (<b>D</b>) and ER are shown close to the plasmalemma. (<b>E</b>) Typical internal organization of red algae chloroplasts showing a single peripheral thylakoid. CV, cored vesicles; ER, endoplasmic reticulum; EP, electron-dense particles; M, mitochondria; N, nucleus; Nu, nucleolus.</p>
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<p>Changes in ultrastructural organization in the chloroplast of <span class="html-italic">Iridaea cordata</span> carpospores after exposure for 4 h to PAR (<b>A</b>,<b>B</b>) and PAR + UV (<b>C</b>,<b>D</b>) treatments at two temperatures. White arrowheads in (<b>B</b>–<b>D</b>) indicate plastoglobuli.</p>
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<p>Summary of major ultrastructural changes in carpospores of <span class="html-italic">Iridaea cordata</span> after 4 h of exposure to PAR and PAR + UV at two temperatures. (<b>A</b>,<b>E</b>) carpospores exposed to PAR at 2 °C; (<b>B</b>) carpospores exposed to PAR + UV at 2 °C; (<b>C</b>,<b>D</b>) carpospores exposed to PAR at 8 °C; (<b>F</b>) carpospores exposed to PAR + UV at 8 °C. CV, cored vesicles; ER, endoplasmic reticulum; EP, electron-dense particles; G, Golgi complex; M, mitochondria; N, nucleus; Nu, nucleolus. White arrowheads in C indicate nuclear membrane pores, while in E plastoglobuli.</p>
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<p>Maximum photochemical efficiency of photosystem II (F<sub>v</sub>/F<sub>m</sub>) of <span class="html-italic">Iridaea cordata</span> carpospores after exposure (<b>A</b>,<b>B</b>) for 4 h to PAR and PAR + UV at two temperatures and recovery (<b>C</b>,<b>D</b>) under low white light (4 μmol photon m<sup>−2</sup> s<sup>−1</sup>). Control was continuously maintained at 4 μmol photon m<sup>−2</sup>s<sup>−1</sup> at 8 °C (mean ± SD, <span class="html-italic">n</span> = 6). The percentage decrease in F<sub>v</sub>/F<sub>m</sub> (<b>A</b>,<b>B</b>) and recovery (<b>C</b>,<b>D</b>) with respect to the control is presented within the bars. Different letters indicate significant differences (<span class="html-italic">p</span> &lt; 0.05, HSD post hoc test).</p>
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<p>Chlorophyll <span class="html-italic">a</span> content in µg Chl-<span class="html-italic">a</span> g<sup>−1</sup> DW, the ratio of carotenoids (A<sub>480nm</sub>) to Chl-<span class="html-italic">a</span> (A<sub>665nm</sub>) in <span class="html-italic">Iridaea cordata</span> carpospores exposed for 4 h to PAR and PAR + UV treatments at 2 and 8 °C, and subsequent 4 h recovery in dim light. Control was continuously maintained at 4 μmol photon m<sup>−2</sup> s<sup>−1</sup> and at 8 °C. Values are means ± S.E. (<span class="html-italic">n</span> = 4). F-values and ANOVA significance are indicated. Different letters indicate significant differences (<span class="html-italic">p</span> &lt; 0.05, HSD post hoc test).</p>
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<p>Spectra of methanol extract of the <span class="html-italic">Iridaea cordata</span> carpospores. (<b>A</b>) Spectra of initial samples. (<b>B</b>,<b>C</b>) Spectra of methanol extracts (against control) of samples following 4 h exposure to UV radiation under two temperature treatments and subsequent 4 h recovery in dim light. Control was kept constant at 4 μmol photon m<sup>−2</sup> s<sup>−1</sup> and 8 °C. Each spectrum represents the average of four measurements.</p>
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23 pages, 6157 KiB  
Article
Stomatal and Non-Stomatal Leaf Responses during Two Sequential Water Stress Cycles in Young Coffea canephora Plants
by Danilo F. Baroni, Guilherme A. R. de Souza, Wallace de P. Bernado, Anne R. Santos, Larissa C. de S. Barcellos, Letícia F. T. Barcelos, Laísa Z. Correia, Claudio M. de Almeida, Abraão C. Verdin Filho, Weverton P. Rodrigues, José C. Ramalho, Miroslava Rakočević and Eliemar Campostrini
Stresses 2024, 4(3), 575-597; https://doi.org/10.3390/stresses4030037 - 9 Sep 2024
Viewed by 1186
Abstract
Understanding the dynamics of physiological changes involved in the acclimation responses of plants after their exposure to repeated cycles of water stress is crucial to selecting resilient genotypes for regions with recurrent drought episodes. Under such background, we tried to respond to questions [...] Read more.
Understanding the dynamics of physiological changes involved in the acclimation responses of plants after their exposure to repeated cycles of water stress is crucial to selecting resilient genotypes for regions with recurrent drought episodes. Under such background, we tried to respond to questions as: (1) Are there differences in the stomatal-related and non-stomatal responses during water stress cycles in different clones of Coffea canephora Pierre ex A. Froehner? (2) Do these C. canephora clones show a different response in each of the two sequential water stress events? (3) Is one previous drought stress event sufficient to induce a kind of “memory” in C. canephora? Seven-month-old plants of two clones (’3V’ and ‘A1’, previously characterized as deeper and lesser deep root growth, respectively) were maintained well-watered (WW) or fully withholding the irrigation, inducing soil water stress (WS) until the soil matric water potential (Ψmsoil) reached ≅ −0.5 MPa (−500 kPa) at a soil depth of 500 mm. Two sequential drought events (drought-1 and drought-2) attained this Ψmsoil after 19 days and were followed by soil rewatering until a complete recovery of leaf net CO2 assimilation rate (Anet) during the recovery-1 and recovery-2 events. The leaf gas exchange, chlorophyll a fluorescence, and leaf reflectance parameters were measured in six-day frequency, while the leaf anatomy was examined only at the end of the second drought cycle. In both drought events, the WS plants showed reduction in stomatal conductance and leaf transpiration. The reduction in internal CO2 diffusion was observed in the second drought cycle, expressed by increased thickness of spongy parenchyma in both clones. Those stomatal and anatomical traits impacted decreasing the Anet in both drought events. The ‘3V’ was less influenced by water stress than the ‘A1’ genotype in Anet, effective quantum yield in PSII photochemistry, photochemical quenching, linear electron transport rate, and photochemical reflectance index during the drought-1, but during the drought-2 event such an advantage disappeared. Such physiological genotype differences were supported by the medium xylem vessel area diminished only in ‘3V’ under WS. In both drought cycles, the recovery of all observed stomatal and non-stomatal responses was usually complete after 12 days of rewatering. The absence of photochemical impacts, namely in the maximum quantum yield of primary photochemical reactions, photosynthetic performance index, and density of reaction centers capable of QA reduction during the drought-2 event, might result from an acclimation response of the clones to WS. In the second drought cycle, the plants showed some improved responses to stress, suggesting “memory” effects as drought acclimation at a recurrent drought. Full article
(This article belongs to the Topic Plant Responses to Environmental Stress)
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Graphical abstract

Graphical abstract
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<p>Soil matric water potential (Ψ<sub>msoil</sub>) at 100 mm cm and 500 mm from the soil surface in the pots of the <span class="html-italic">C. canephora</span> var. Robusta genotypes of (<b>A</b>) ‘3V’ and (<b>B</b>) ‘A1’ under well-watered (WW) and water stressed (WS) conditions. The water restriction was imposed during the drought-1 and drought-2 events, after which the soil was rewatered (and recovery-1 and recovery-2 events).</p>
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<p>Leaf gas exchanges of two genotypes (Gen) of <span class="html-italic">C. canephora</span> var. Robusta (‘3V’ and ‘A1’) grown under two water availability conditions [Wat, well-watered (WW) and water stress (WS)], over 12 time-points of six-day intervals (Day) during drought-1 and drought-2 and respective recovery events: (<b>A</b>) net CO<sub>2</sub> assimilation rate (<span class="html-italic">A</span><sub>net</sub>), (<b>B</b>) stomatal conductance to water (<span class="html-italic">g</span><sub>s</sub>), (<b>C</b>) transpiration rate (<span class="html-italic">E</span>), and (<b>D</b>) leaf-to-air vapor pressure deficit (VPD<sub>leaf-air</sub>). Inside the figures, the different lowercase letters indicate the significant difference among the time-points for each water regime (blue for WW and olive green for WS); different uppercase letters indicate the comparison between water availabilities for each time-point of observation (blue for WW and olive green for WS); and different superscript black ■ signs indicate that ‘3V’ was statistically superior to ‘A1’ at that time-point. Mean ± SE and ANOVA <span class="html-italic">p</span>-values (n = 7) for effects of three factors (water availability, genotype, and day of observation) and their interactions are shown. The significant <span class="html-italic">p</span>-values were marked in bold in the upper part of each graph.</p>
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<p>Instantaneous water-use efficiency (WUE, <span class="html-italic">A</span><sub>net</sub>/<span class="html-italic">E</span>) of two genotypes (Gen) of <span class="html-italic">C. canephora</span> var. Robusta (‘3V’ and ‘A1’) grown under two water availability conditions [Wat, well-watered (WW) and water stress (WS)], over 12 time-points of six-day intervals (Day) during drought-1 and drought-2 and respective recovery events. Inside the figure, different lowercase letters indicate the significant difference among the day-time points for each water regime (blue for WW and olive green for WS); different uppercase letters indicate the comparison between water availabilities for each time-point of observation (blue for WW and olive green for WS). Mean ± SE and ANOVA <span class="html-italic">p</span>-values (n = 7) for effects of three factors (water availability, genotype, and day of observation) and their interactions are shown. The significant <span class="html-italic">p</span>-values were marked in bold in the upper part of each graph.</p>
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<p>Variation of OJIP indexes of two genotypes (Gen) of <span class="html-italic">C. canephora</span> var. Robusta (‘3V’ and ‘A1’) grown under two water availability conditions [Wat, well-watered (WW) and water stress (WS)] over 12 time-points of six-day intervals (Day) during drought-1 and drought-2 and respective recovery events: (<b>A</b>) maximum quantum yield of primary photochemical reactions (ΦP<sub>0</sub>), (<b>B</b>) probability of electron transfer from Q<sub>A</sub>-to-electron transport chain beyond Q<sub>A</sub> (ΨE<sub>0</sub>), (<b>C</b>) photosynthetic performance index (PI<sub>ABS</sub>), and (<b>D</b>) density of reaction centers capable of Q<sub>A</sub> reduction (RC/CS<sub>0</sub>). Inside the figures, the different lowercase letters indicate the significant difference among the time-points for each water regime (blue for WW and olive green for WS); different uppercase letters indicate the comparison between water availabilities for each day of observation (blue for WW and olive green for WS); superscript black ■ signs indicate that ‘3V’ was statistically superior to ‘A1’, while superscript black ● signs indicate that ‘A1’ clone was statistically superior to ‘3V’ clone at that time-point. Mean ± SE and ANOVA <span class="html-italic">p</span>-values (n = 7) for effects of three factors (water availability, genotype, and day of observation) and their interactions are shown. The significant <span class="html-italic">p</span>-values were marked in bold.</p>
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<p>Variation of modulated chlorophyll <span class="html-italic">a</span> fluorescence indexes of two genotypes (Gen) of <span class="html-italic">C. canephora</span> var. Robusta (‘3V’ and ‘A1’) grown under two water availability conditions [Wat, well-watered (WW) and water stress (WS)] over 12 time-points of six-day intervals (Day) during drought-1 and drought-2 and respective recovery events: (<b>A</b>) effective quantum yield in PSII photochemistry (Φ<sub>PSII</sub>), (<b>B</b>) photochemical quenching (qP), (<b>C</b>) non-photochemical quenching (NPQ), and (<b>D</b>) linear electron transport rate (ETR). Inside the figures, the different lowercase letters indicate the significant difference among the time-points for each water regime (blue for WW and olive green for WS); different uppercase letters indicate the comparison between water availabilities for each day of observation (blue for WW and olive green for WS); different superscript black ■ signs indicate that ‘3V’ was statistically superior to ‘A1’, while superscript black ● signs indicate that ‘A1’ clone was statistically superior to ‘3V’ clone at that time-point. Mean ± SE and ANOVA <span class="html-italic">P</span>-values (n = 7) for effects of three factors (water availability, genotype, and day of observation) and their interactions are shown. The significant <span class="html-italic">P</span>-values were marked in bold.</p>
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<p>Variation of spectral reflectance indices of leaf adaxial surface of two genotypes (Gen) of C. canephora var. Robusta (‘3V’ and ‘A1’) grown under two water availability conditions [Wat, well-watered (WW) and water stress (WS)] over 12 time-points of six-day intervals (Day) during drought-1 and drought-2 and respective recovery events: (<b>A</b>) green chlorophyll index (GCI), (<b>B</b>) carotenoid reflectance index (CRI), (<b>C</b>) photochemical reflectance index (PRI), and (<b>D</b>) structure intensive reflectance index (SIPI). Inside the figures, the different lowercase letters indicate the significant difference among the time-points for each water regime (blue for WW and olive green for WS); different uppercase letters indicate the comparison between water availabilities for each day of observation (blue for WW and olive green for WS); different superscript black ■ signs indicate that ‘3V’ was statistically superior to ‘A1’, while superscript black ● signs indicate that ‘A1’ clone was statistically superior to ‘3V’ clone at that time-point. Mean ± SE and ANOVA <span class="html-italic">p</span>-values (n = 7) for effects of three factors (water availability, genotype, and day of observation) and their interactions are shown. The significant <span class="html-italic">p</span>-values were marked in bold.</p>
Full article ">Figure 7
<p>Representative area of leaf xylem vessel (µm<sup>2</sup>) measured in <span class="html-italic">C. canephora</span> var. Robusta clones (‘3V’ and ‘A1’) under well-watered (WW) and water stress (WS) conditions: (<b>A</b>) A1-WW, (<b>B</b>) 3V-WW, (<b>C</b>) A1-WS, and (<b>D</b>) 3V-WS, evaluated at the end of the second drought cycle. A scale of 100 µm is shown.</p>
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<p>Diagram of the two drought cycles. Transplant followed by drought-1 event last for 19 days (until −500 kPa of Ψ<sub>msoil</sub> was reached), followed by a 31-day period for a whole plant recovery (including 12-day period of recovery-1 event). The 2nd drought cycle was then applied, similarly to the 1st drought cycle, by withholding irrigation until the −500 kPa of Ψ<sub>msoil</sub> was reached (drought-2 event) and followed by another 12 days of recovery-2 event.</p>
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22 pages, 2735 KiB  
Article
Environmental Sustainability of Building Materials in Turkey: Reference Information Recommendations for European Green Deal Declarations
by Şerife Ak, Osman Aytekin, Hakan Kuşan and İsmail Zorluer
Buildings 2024, 14(4), 889; https://doi.org/10.3390/buildings14040889 - 25 Mar 2024
Viewed by 2211
Abstract
This study provides weight and normalization reference information for declaring the environmental information of building materials produced and exported in Turkey. Reference information was first determined for the global warming potential based on greenhouse gas (GHG) emissions, which is the subject of the [...] Read more.
This study provides weight and normalization reference information for declaring the environmental information of building materials produced and exported in Turkey. Reference information was first determined for the global warming potential based on greenhouse gas (GHG) emissions, which is the subject of the European Union Green Deal Carbon Border Adjustment Mechanism (CBAM). For a more holistic approach, reference information is also recommended for environmental impact categories acidification, air pollution, ecological toxicity, eutrophication, fossil fuel depletion, human health, indoor air quality, land use, ozone depletion, photochemical smog formation, and water depletion, in addition to GHG emissions. Reference information is determined based on the life cycle assessment (LCA) methodology defined in the international standards ISO 14040 and ISO 14044. Semi-structured interviews were held with twenty-one industry stakeholders in Turkey to determine the weight reference values. The results obtained from the semi-structured interviews were combined using the analytic hierarchy process (AHP) method. Normalization reference information was determined by compiling Turkey’s national emission values. The suggested reference information has been tested using a case study. Total environmental impact scores were calculated for floor coverings and exterior wall finishes, including global warming potentials based on GHG emissions, and eleven other environmental impact categories. The findings support the need to use regional reference information in Turkey. The reference information recommended in this study can be used both in declarations within the scope of the EU Green Deal and in other possible environmental impact declarations resulting from building materials. Full article
(This article belongs to the Collection Sustainable and Green Construction Materials)
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Figure 1

Figure 1
<p>The framework of the study.</p>
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<p>Elements of LCA defined in ISO 14040.</p>
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<p>Hierarchical structure for obtaining the weights of environmental impact categories.</p>
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<p>Weight reference values and BEES Stakeholder Panel weights.</p>
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<p>Global warming potentials due to GHG emissions of flooring materials.</p>
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<p>Total environmental impact scores of flooring materials calculated according to different weights and normalization values.</p>
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<p>Global warming potentials due to GHG emissions of exterior wall finish materials.</p>
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<p>Total environmental impact scores of exterior wall finish materials calculated according to different weights and normalization values.</p>
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14 pages, 1030 KiB  
Article
Exogenous Silicon Application Improves Chilling Injury Tolerance and Photosynthetic Performance of Citrus
by Mireille Asanzi Mvondo-She, Jacob Mashilo, Auges Gatabazi, Ashwell Rungano Ndhlala and Mark Delmege Laing
Agronomy 2024, 14(1), 139; https://doi.org/10.3390/agronomy14010139 - 5 Jan 2024
Cited by 3 | Viewed by 1402
Abstract
Low-temperature stress is an important limiting factor affecting citrus growth and fruit yields. Therefore, increasing citrus cold stress tolerance may enhance the growth, yield, and quality of citrus production in marginal areas. The objective of this study was to determine the efficacy of [...] Read more.
Low-temperature stress is an important limiting factor affecting citrus growth and fruit yields. Therefore, increasing citrus cold stress tolerance may enhance the growth, yield, and quality of citrus production in marginal areas. The objective of this study was to determine the efficacy of silicon (Si) fertilizer application on cold-tolerance enhancement in citrus. Two citrus cultivars (Delta and Nules) were subjected to Si fertilization (control, 1000 mg L−1) and cold-stress temperature treatments (control and 0 °C for 72 h) using a 2 × 2 × 2 factorial treatment structure with six replications. Leaf gas exchange and chlorophyll fluorescence parameters, such as net photosynthetic rate (A), stomatal conductance (gs), transpiration rate (Tr), internal CO2 concentration (Ci), intrinsic water-use efficiency (iWUE), minimal fluorescence (Fo), maximum fluorescence (Fm), maximum quantum efficiency of PSII primary photochemistry of dark-adapted leaves (Fv/Fm), maximum quantum efficiency of PSII primary photochemistry of dark-/light-adapted leaves (F’v/F’m), electron transport rate (ETR), non-photochemical quenching (NPQ), and the relative measure of electron transport to oxygen molecules (ETR/A), were measured. The application of Si drenching to trees that were subsequently exposed to cold stress reduced gs, Tr, and Ci but improved iWUE and Fo in both cultivars compared to the Si-untreated trees. In addition, specific adaptation mechanisms were found in the two citrus species; NPQ and ETR were improved in Si-treated Valencia trees, while A, Fm, and ETR/A were improved in Clementine trees under chilling stress conditions. The current research findings indicate the potential of Si application to enhance cold stress tolerance in citrus, which can provide a strategy for growing citrus in arid and semi-arid regions that may experience cold stress. Overall, after the application of silicon drenching, the cold-sensitive citrus Valencia cultivar became as cold-tolerant as the cold-tolerant Clementine cultivar. Full article
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<p>The effect of Si treatments (Si+ (1000 mg L<sup>−1</sup>) and Si− (0 mg L<sup>−1</sup>)) on (<b>A</b>) the effective quantum yield of photosystem II, (<b>B</b>) the maximum quantum yield of the efficiency of photosystem II, (<b>C</b>) the minimum fluorescence of dark-adapted leaves, and (<b>D</b>) the maximum fluorescence of dark-adapted leaves of ‘Valencia’ and ‘Clementine’ after chilling injury stress at 0 °C. Data are means ± standard errors. Error bars sharing a letter are not significantly different.</p>
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<p>The effect of Si treatments (Si+ (1000 mg L<sup>−1</sup>) and Si− (0 mg L<sup>−1</sup>)) on (<b>A</b>) non-photochemical quenching, (<b>B</b>) electron transport rate, and (<b>C</b>) photorespiration (ETR/A) of ‘Valencia’ and ‘Clementine’ leaves during chilling injury stress at 0 °C. Data are means ± standard errors. Error bars sharing a letter are not significantly different.</p>
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<p>The effect of Si treatments (Si+ (1000 mg L<sup>−1</sup>) and Si− (0 mg L<sup>−1</sup>)) on (<b>A</b>) the photosynthetic rate, (<b>B</b>) the stomatal conductance, (<b>C</b>) the transpiration rate, (<b>D</b>) the internal carbon dioxide concentration, and (<b>E</b>) the intrinsic water-use efficiency of ‘Valencia’ and ‘Clementine’ leaves after chilling injury stress at 0 °C. Data are means ± standard errors. Error bars sharing a letter are not significantly different.</p>
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15 pages, 1631 KiB  
Article
Unveiling the Environmental Impacts of Concentrated Latex Manufacturing in Sri Lanka through a Life Cycle Assessment
by Pasan Dunuwila, V. H. L. Rodrigo, Ichiro Daigo and Naohiro Goto
Resources 2024, 13(1), 5; https://doi.org/10.3390/resources13010005 - 25 Dec 2023
Cited by 2 | Viewed by 3938
Abstract
Sri Lanka is a top producer of premium quality concentrated latex (CL), which becomes a base material for dipped rubber products such as gloves and condoms. The processing of CL is resource-intensive, requiring significant amounts of energy, fuel, water, and chemicals. This process [...] Read more.
Sri Lanka is a top producer of premium quality concentrated latex (CL), which becomes a base material for dipped rubber products such as gloves and condoms. The processing of CL is resource-intensive, requiring significant amounts of energy, fuel, water, and chemicals. This process leads to various environmental issues such as wastewater pollution, malodor, and greenhouse gas emissions. Several environmental life cycle assessments (LCA) have been conducted at international and local levels to address the aforesaid issues. However, LCAs encapsulating different environmental impact areas on CL processing in Sri Lanka are absent. The study revealed that electricity usage was the main hotspot of the environmental burden, significantly impacting abiotic depletion (fossil fuels), global warming potential, ozone layer depletion, photochemical oxidation, and acidification. Heavy reliance on coal in the Sri Lankan power grid was identified as the root of this trend. The study suggested two viable options to mitigate the environmental impact: installing inverters to centrifuge separators and solar systems in the factories. The second option was deemed more effective, reducing acidification, photochemical oxidation, and global warming potential by approximately 37%, 36%, and 28%, respectively. Relevant officials may immediately consider these improvement options and collaborate to pave the way to a sustainable natural rubber industry. Full article
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<p>Concentrated latex manufacturing process. CL, TZ, DAHP, TMTD, and DBM refer to concentrated latex; the mixture of tetramethylthiuram disulfide (TMTD) and zinc oxide (ZnO); di ammonium hydrogen phosphate; tetramethylthiuram disulfide; and dry blanket milling. The flow diagram was only meant to demonstrate only the main activity flow with inputs, and so linkages to subsidiary were not shown to avoid complexity.</p>
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<p>Overview of the research methodology. SPBT and EPBT refer to simple payback time and environmental payback time, respectively.</p>
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<p>Contribution of in-factory activities to respective impact categories (except transportation). Black values represent the overall impact, excluding transportation, while red values represent the total impact, including transportation. For more information, please refer to <a href="#app1-resources-13-00005" class="html-app">Table S3 in the supplementary material</a>.</p>
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<p>Reduction potentials of improvement options under each impact category. Negative and positive scales respectively denote reductions and increments in environmental impacts from the baseline.</p>
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18 pages, 18567 KiB  
Article
Effects of Coverlys TF150® on the Photosynthetic Characteristics of Grape
by Zhonghan Li, Enshun Jiang, Minghui Liu, Qinghua Sun, Zhen Gao and Yuanpeng Du
Int. J. Mol. Sci. 2023, 24(23), 16659; https://doi.org/10.3390/ijms242316659 - 23 Nov 2023
Cited by 1 | Viewed by 1114
Abstract
Grape rain-shelter cultivation is a widely employed practice in China. At present, the most commonly used rain shelter film materials are polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), and polyolefin (PO). Coverlys TF150® is a woven fabric with an internal [...] Read more.
Grape rain-shelter cultivation is a widely employed practice in China. At present, the most commonly used rain shelter film materials are polyvinyl chloride (PVC), polyethylene (PE), ethylene-vinyl acetate copolymer (EVA), and polyolefin (PO). Coverlys TF150® is a woven fabric with an internal antifoggy PE coating that has not yet been popularized as a rain shelter film for grapes in China. To investigate the effects of Coverlys TF150® on grapes, we measured the microdomain environment, leaf development, and photosynthetic characteristics of ‘Miguang’ (Vitis vinifera × V. labrusca) under rain-shelter cultivation and performed transcriptome analysis. The results showed that Coverlys TF150® significantly reduced (p < 0.05) the light intensity, temperature, and humidity compared with PO film, increased the chlorophyll content and leaf thickness (particularly palisade tissue thickness), and increased stomatal density and stomatal opening from 10:00 to 14:00. Coverlys TF150® was observed to improve the maximum efficiency of photosystem II (Fv/Fm), photochemical quenching (qP), the electron transfer rate (ETR), and the actual photochemical efficiency (ΦPSII) from 10:00 to 14:00. Moreover, the net photosynthetic rate (Pn), intercellular CO2 concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr) of grape leaves significantly increased (p < 0.05) from 10:00 to 14:00. RNA-Seq analysis of the grape leaves at 8:00, 10:00, and 12:00 revealed 1388, 1562, and 1436 differential genes at these points in time, respectively. KEGG enrichment analysis showed the occurrence of protein processing in the endoplasmic reticulum. Plant hormone signal transduction and plant-pathogen interaction were identified as the metabolic pathways with the highest differential gene expression enrichment. The psbA encoding D1 protein was significantly up-regulated in both CO10vsPO10 and CO12vsPO12, while the sHSPs family genes were significantly down-regulated in all time periods, and thus may play an important role in the maintenance of the photosystem II (PSII) activity in grape leaves under Coverlys TF150®. Compared with PO film, the PSI-related gene psaB was up-regulated, indicating the ability of Coverlys TF150® to better maintain PSI activity. Compared with PO film, the abolic acid receptacle-associated gene PYL1 was down-regulated at all time periods under the Coverlys TF150® treatment, while PP2C47 was significantly up-regulated in CO10vsPO10 and CO12vsPO12, inducing stomatal closure. The results reveal that Coverlys TF150® alleviates the stress of high temperature and strong light compared with PO film, improves the photosynthetic capacity of grape leaves, and reduces the midday depression of photosynthesis. Full article
(This article belongs to the Special Issue Molecular Research in Fruit Crop)
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<p>Effects of Coverlys TF150<sup>®</sup> and PO film on the grape canopy microdomain environment. (<b>A</b>) Photosynthetically active radiation measured at 12:00. (<b>B</b>) Photosynthetically active radiation measured at 12:00. (<b>C</b>) Maximum temperature. (<b>D</b>) Minimum temperature. (<b>E</b>) Maximum humidity. (<b>F</b>) Minimum humidity. Note: M-D stands for date, M stands for Month, D stands for day.</p>
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<p>Effects of Coverlys TF150<sup>®</sup> and PO film on the growth and development of grape leaves. (<b>A</b>) Leaf area. (<b>B</b>) Leaf thickness. (<b>C</b>) Leaf weight. (<b>D</b>) Chlorophyll content. (<b>E</b>) Comparison of Coverlys TF150<sup>®</sup> and PO film paraffin sections. (<b>F</b>) Stomatal opening. (<b>G</b>) Stomatal density. (<b>H</b>,<b>I</b>) Stomatal phenotype (Scale bar: 100 μm and 20 μm). Note: * indicates significant differences (<span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Effects of Coverlys TF150<sup>®</sup> and PO film on the photosynthetic characteristics of grape leaves. (<b>A</b>) Net photosynthetic rate, P<sub>n</sub>. (<b>B</b>) Stomatal conductance, G<sub>s</sub>. (<b>C</b>) Intercellular CO<sub>2</sub> concentration, C<sub>i</sub>. (<b>D</b>) Transpiration rate, T<sub>r</sub>. (<b>E</b>) Maximum PSII quantum yield, Fv/Fm. (<b>F</b>) Actual photochemical efficiency of PSII, Φ<sub>PSII</sub>. (<b>G</b>) Photochemical quenching coefficient, qP. (<b>H</b>) Electron transport rate, ETR. Note: * indicates significant differences (<span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Analysis of gene differential expression in leaves of Coverlys TF150<sup>®</sup> and PO film at 8:00, 10:00, and 12:00. (<b>A</b>–<b>C</b>) CO8vsPO8, CO10vsPO10, and CO12vsPO12 volcano map analysis. log<sub>2</sub>(fold change) transformation was used for the x-axis and log<sub>10</sub>(<span class="html-italic">p</span> value) was used for the y-axis. Red represents up-regulation, green represents down-regulation, and gray represents no significant difference between the experimental and control groups. (<b>D</b>) Venn diagram showing the number of differentially expressed genes in grape leaves under Coverlys TF150<sup>®</sup> and PO film at 8:00, 10:00, and 12:00. note: CO stands for Coverlys TF150<sup>®</sup>, PO stands for PO film, 8, 10, and 12 represent 8:00, 10:00, and 12:00, respectively.</p>
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<p>Bubble diagram of the top 20 KEGG enrichment pathways. Entries with larger bubbles contain more difference-protein coding genes. The smaller the enrichment <span class="html-italic">p</span>-value, the greater the significance. (<b>A</b>–<b>C</b>) CO8vsPO8, CO10vsPO10, and CO12vsPO12 KEGG enriched top 20 bubble diagram.</p>
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<p>Differential expression analysis of photosystem II-related genes. (<b>A</b>) Schematic diagram of the light reaction of photosynthesis process. (<b>B</b>) Differentially expressed photosystem II-related genes in grape leaves under Coverlys TF150<sup>®</sup> and PO film. Note: * indicates significant differences (<span class="html-italic">p</span> &lt; 0.05).</p>
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<p>Differentially expressed genes in the ABA signaling pathway of grape leaves under Coverlys TF150<sup>®</sup> and PO film. Note: PYR/PYL, abscisic acid receptor of PYR/PYL family; PP2C, protein phosphatase 2C; SnRK2, serine/threonine-protein kinase; ABF, ABA-responsive element binding factor.</p>
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<p>Differential expression of the heat shock protein and heat shock protein transcription factor genes in grape leaves under Coverlys TF150<sup>®</sup> and PO film. Note: * indicates significant differences (<span class="html-italic">p</span> &lt; 0.05).</p>
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18 pages, 2437 KiB  
Article
Towards Cleaner Cities: An Analysis of the Impact of Bus Fleet Decomposition on PM and NOX Emissions Reduction in Sustainable Public Transport
by Artur Jaworski, Vasyl Mateichyk, Hubert Kuszewski, Maksymilian Mądziel, Paweł Woś, Bożena Babiarz, Mirosław Śmieszek and Sławomir Porada
Energies 2023, 16(19), 6956; https://doi.org/10.3390/en16196956 - 5 Oct 2023
Cited by 1 | Viewed by 1664
Abstract
The problem of poor air quality in urban areas has a negative impact on the health of residents. This is especially important during periods of smog. In Poland, as in other countries, the problem of poor air quality, especially during the winter season, [...] Read more.
The problem of poor air quality in urban areas has a negative impact on the health of residents. This is especially important during periods of smog. In Poland, as in other countries, the problem of poor air quality, especially during the winter season, is associated with a high concentration of particulate pollutants in ambient air (PM10, PM2.5). Sources of particulate emissions, in addition to solid-fuel boilers, include means of transportation, especially those equipped with diesel engines. In turn, during periods of strong sunshine (spring and summer), the problem of photochemical smog, whose precursors are nitrogen oxides NOX, arises in urban areas. Their main sources of emissions are internal combustion engines. Therefore, to improve air quality in urban areas, changes are being made in the transport sector, among which is upgrading the fleet of urban transport vehicles to low- or zero-emission vehicles, which are more environmentally friendly. In addition, measures that reduce the harmfulness of the transportation sector to air quality include the introduction of clean transportation zones, as well as park-and-ride (P&R) systems. The purpose of this article is to present the results in terms of PM10, PM2.5, and NOx emission reductions, implemented over a period of two years (2021–2022) in the area of the Rzeszow agglomeration, related to the modernization of the suburban bus fleet and the implementation of a P&R system for passenger cars. The results of the study were compared with the value of estimated emissions from coal-fired boilers used for residential heating and hot water, which also contribute to smog. Thanks to the implementation of the project, i.e., the replacement of 52 old buses with new buses of the Euro VI emission class and the construction of new P&R spaces, the total average annual reduction in emissions amounted to approximately 703.6 kg of PM10, approximately 692.7 kg of PM2.5, and a reduction of approximately 10.4 tons of NOX. Full article
(This article belongs to the Special Issue Energy Transition and Environmental Sustainability II)
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<p>Average levels of NO<sub>X</sub>, PM<sub>2.5</sub>, and PM<sub>10</sub> in the air in Rzeszow in 2019 (data from the monitoring station on Pilsudski Street).</p>
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<p>General diagram showing the methodology for calculating PM and NO<sub>X</sub> emissions for buses and passenger cars.</p>
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<p>Diagram showing authors’ logic for the PM and NO<sub>X</sub> emission calculation methodology.</p>
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<p>The weather conditions characteristic of the Rzeszow agglomeration (macroscale calculation input data).</p>
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<p>Map illustrating the research area with marked locations of park-and-ride facilities [<a href="#B15-energies-16-06956" class="html-bibr">15</a>].</p>
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<p>The percentages of passenger cars by (<b>a</b>) emission standard and (<b>b</b>) fuel used.</p>
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<p>Relative emissions of PM<sub>10</sub>, PM<sub>2.5</sub>, and NO<sub>X</sub> from buses for the analyzed variants.</p>
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14 pages, 3177 KiB  
Article
Photochemical Release of Dissolved Organic Nitrogen from Algal Detritus and Sediment Particles in Lake Taihu, China
by Yanan Liu and Xiaolong Yao
Water 2023, 15(19), 3346; https://doi.org/10.3390/w15193346 - 24 Sep 2023
Cited by 2 | Viewed by 1957
Abstract
Solar irradiation in aquatic systems can induce the conversion of substances from the solid to the dissolved phase (photodissolution). Yet, the photochemical release of dissolved organic nitrogen (DON) from internal particles in lakes remains largely unknown. In this study, suspensions of algal detritus [...] Read more.
Solar irradiation in aquatic systems can induce the conversion of substances from the solid to the dissolved phase (photodissolution). Yet, the photochemical release of dissolved organic nitrogen (DON) from internal particles in lakes remains largely unknown. In this study, suspensions of algal detritus and sediment particles from a shallow eutrophic lake were exposed to simulated solar irradiation, and the release and compositional changes of dissolved organic matter were explored by measuring their UV–Visible absorption spectroscopy and ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The photochemical release of inorganic nitrogen during the incubations was also investigated. Results showed that light irradiation induced stronger dissolved organic carbon and DON production in the algal detritus suspensions, with release rates of 1.17 mg C L−1 h−1 and 0.14 mg N L−1 h−1, respectively, at an algal detritus concentration of 0.1 dry g L−1. Light irradiation also induced compositional changes of DON in both algal and sediment suspensions. A larger number of DON molecules with lower molecular weight were continuously released in the algal suspensions, e.g., the total number of DON formulas increased from 1349 to 4135 during an 8 h irradiation. In contrast, upon irradiation of sediment suspensions, DON showed decreased molecular diversity and increased aromaticity. The photochemical release of ammonium (photoammonification) was also higher in the algal suspensions with a rate of 0.015 mg N L−1 h−1, which may contribute to the eutrophication of the lake. This study provides new molecular insights into the photochemical release of DON from typical internal particles in eutrophic lakes. Full article
(This article belongs to the Special Issue Internal Nutrient Cycling in Lakes and Reservoirs)
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<p>Sampling sites of the algae and sediment used in this study.</p>
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<p>Changes in the dissolved organic carbon (DOC) (<b>a</b>) and dissolved organic nitrogen (DON) (<b>b</b>) concentrations and UV–Visible parameters of DOM in the irradiated algal detritus suspensions. The UV–Visible parameters of DOM include spectral absorption coefficients <span class="html-italic">a</span>(254) (<b>c</b>), spectral slope <span class="html-italic">S</span><sub>275–295</sub> (<b>d</b>), molecular size (<span class="html-italic">a</span>(250):<span class="html-italic">a</span>(365)) (<b>e</b>), and specific ultraviolet absorption at 254 nm (SUVA<sub>254</sub>) (<b>f</b>).</p>
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<p>Changes in the dissolved organic carbon (DOC) (<b>a</b>) and dissolved organic nitrogen (DON) (<b>b</b>) concentrations and UV–Visible parameters of DOM in the irradiated sediment suspensions. The UV–Visible parameters of DOM include spectral absorption coefficients <span class="html-italic">a</span>(254) (<b>c</b>), spectral slope <span class="html-italic">S</span><sub>275–295</sub> (<b>d</b>), molecular size (<span class="html-italic">a</span>(250):<span class="html-italic">a</span>(365)) (<b>e</b>), and specific ultraviolet absorption at 254 nm (SUVA<sub>254</sub>) (<b>f</b>).</p>
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<p>Van Krevelen (VK) plots of N-containing formulae during the incubation of algal (<b>a</b>,<b>b</b>) and sediment (<b>c</b>,<b>d</b>) suspensions upon exposure to simulated sunlight at 0 (<b>a</b>,<b>c</b>), and 8 (<b>b</b>,<b>d</b>) h.</p>
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<p>The number (<b>a</b>,<b>b</b>) and normalized intensity (<b>c</b>,<b>d</b>) of N-containing formulas assigned to each compound class in irradiated algal (<b>a</b>,<b>c</b>) and sediment (<b>b</b>,<b>d</b>) suspensions at different incubation time.</p>
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<p>The number (<b>a</b>) and intensity (<b>b</b>) percentages of each class of N-containing formulas subcategorized by van Krevelen (VK) plots in irradiated algal and sediment suspensions at different incubation time.</p>
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<p>Photochemical release of inorganic nutrients from algal detritus (<b>a</b>–<b>c</b>) and sediment (<b>d</b>–<b>f</b>) particle suspensions.</p>
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22 pages, 6250 KiB  
Article
Mesoporous Dual-Semiconductor ZnS/CdS Nanocomposites as Efficient Visible Light Photocatalysts for Hydrogen Generation
by Ioannis Vamvasakis, Evangelos K. Andreou and Gerasimos S. Armatas
Nanomaterials 2023, 13(17), 2426; https://doi.org/10.3390/nano13172426 - 26 Aug 2023
Cited by 7 | Viewed by 2174
Abstract
The development of functional catalysts for the photogeneration of hydrogen (H2) via water-splitting is crucial in the pursuit of sustainable energy solutions. To that end, metal-sulfide semiconductors, such as CdS and ZnS, can play a significant role in the process due [...] Read more.
The development of functional catalysts for the photogeneration of hydrogen (H2) via water-splitting is crucial in the pursuit of sustainable energy solutions. To that end, metal-sulfide semiconductors, such as CdS and ZnS, can play a significant role in the process due to their interesting optoelectronic and catalytic properties. However, inefficient charge-carrier dissociation and poor photochemical stability remain significant limitations to photocatalytic efficiency. Herein, dual-semiconductor nanocomposites of ZnS/CdS nanocrystal assemblies (NCAs) are developed as efficient visible light photocatalysts for H2 generation. The resultant materials, synthesized via a polymer-templated self-polymerization method, comprise a unique combination of ~5–7 nm-sized metal-sulfide nanoparticles that are interlinked to form a 3D open-pore structure with large internal surface area (up to 285 m2 g−1) and uniform pores (circa 6–7 nm). By adjusting the ratio of constituent nanoparticles, the optimized ZnS/CdS catalyst with 50 wt.% ZnS content demonstrates a remarkable stability and visible light H2-evolution activity (~29 mmol g−1 h−1 mass activity) with an apparent quantum yield (AQY) of 60% at 420 nm. Photocatalytic evaluation experiments combined with electrochemical and spectroscopic studies suggest that the superior photocatalytic performance of these materials stems from the accessible 3D open-pore structure and the efficient defect-mediated charge transfer mechanism at the ZnS/CdS nanointerfaces. Overall, this work provides a new perspective for designing functional and stable photocatalytic materials for sustainable H2 production. Full article
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<p>(<b>a</b>) Schematic representation of the synthetic procedure of mesoporous ZnS/CdS NCAs. (<b>b</b>) Typical XRD patterns of mesoporous CdS and ZnS NCAs and the as-prepared ZnS/CdS nanocomposites with different ZnS loadings.</p>
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<p>(<b>a</b>) Typical FE-SEM image, (<b>b</b>) EDS mappings of Cd, Zn and S elements, (<b>c</b>) TEM image and high magnification TEM image (inset) showing CdS (yellow circles) and ZnS (white circles) nanoparticles in intimate contact, and (<b>d</b>) HRTEM image for the mesoporous 50-ZnS/CdS nanocomposite. In HRTEM, the lattice fringes with d-spacings of 3.1 and 3.4 Å are indexed to the (111) planes of the cubic structures of ZnS (white lines) and CdS (yellow lines), respectively.</p>
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<p>(<b>a</b>) Cd 3d, (<b>b</b>) Zn 2p and (<b>c</b>) S 2p XPS core-level spectra of mesoporous CdS and ZnS NCAs and the 50-ZnS/CdS nanocomposite.</p>
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<p>(<b>a</b>) Comparative N<sub>2</sub> adsorption (filled cycles) and desorption (open cycles) isotherms at −196 °C and (inset) the corresponding NLDFT pore size distribution plots calculated from the adsorption branch of isotherms for the mesoporous CdS, ZnS and 50-ZnS/CdS NCAs. For clarity, the isotherms of 50-ZnS/CdS and ZnS NCAs are offset by 50 and 100 cm<sup>3</sup> g<sup>−1</sup>, respectively. (<b>b</b>) UV-vis/NIR diffuse reflectance spectra and (<b>c</b>) Tauc plots (i.e., the curves of (αhν)<sup>2</sup> versus photon energy (hν), where α, h and ν are the absorption coefficient, Planck’s constant and light frequency, respectively) of mesoporous CdS, ZnS and ZnS/CdS NCAs with different wt.% ZnS content. Inset: magnification of the Tauc plot in the energy range of 2.2–3.0 eV for clarity.</p>
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<p>(<b>a</b>) Photocatalytic H<sub>2</sub> evolution activities for mesoporous CdS, ZnS and the different ZnS/CdS NCAs, together with the ZnS/CdS bulk and ZnS/CdS RNAs reference catalysts with 50 wt.% ZnS content. The photocatalytic reactions were carried out in an airtight reactor, using 1 mg mL<sup>−1</sup> catalyst concentration in a 0.35 M Na<sub>2</sub>S and 0.25 M Na<sub>2</sub>SO<sub>3</sub> aqueous electrolyte. (<b>b</b>) Photocatalytic H<sub>2</sub> evolution rates for the mesoporous 50-ZnS/CdS catalyst (1 mg mL<sup>−1</sup> catalyst concentration) using different concentrations of Na<sub>2</sub>S/Na<sub>2</sub>SO<sub>3</sub> reagents and (<b>c</b>) different mass loadings of the catalyst in a 1.4 M Na<sub>2</sub>S and 1.0 M Na<sub>2</sub>SO<sub>3</sub> aqueous electrolyte. (<b>d</b>) Photocatalytic recycling tests of the 50-ZnS/CdS catalyst (1 mg mL<sup>−1</sup>) in a 1.4 M Na<sub>2</sub>S and 1.0 M Na<sub>2</sub>SO<sub>3</sub> aqueous electrolyte. All the H<sub>2</sub>-evolution rates obtained as an average over the initial 3-h reaction period. All photocatalytic tests were conducted under visible light irradiation using a 300 W Xenon light source with a UV cutoff filter (λ ≥ 420 nm).</p>
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<p>(<b>a</b>) Mott–Schottky plots where the E<sub>FB</sub> values are obtained from the intercepts of the extrapolated linear fits of the 1/C<sup>2</sup> vs. potential curves, (<b>b</b>) energy band diagrams (the band-edge diagram of the ZnS/CdS bulk sample with 50 wt.% ZnS is also given) and (<b>c</b>) EIS Nyquist plots and equivalent circuit model (inset) for the mesoporous CdS, ZnS and ZnS/CdS NCAs. (<b>d</b>) Comparative time-resolved photoluminescence (TR-PL) decay curves of mesoporous CdS and 50-ZnS/CdS NCAs and ZnS/CdS bulk reference with 50 wt.% ZnS content.</p>
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<p>(<b>a</b>) Schematic energy diagram for the point defect states in ZnS (V<sub>S</sub> = sulfur vacancy, I<sub>S</sub> = interstitial sulfur, V<sub>Zn</sub> = zinc vacancy, and I<sub>Zn</sub> = interstitial zinc). The defect-state energy levels are estimated according to the peak positions of the ZnS NCAs PL spectrum. (<b>b</b>) Schematic illustration of the proposed quasi-type-II charge-transfer and visible light photocatalytic H<sub>2</sub>-generation mechanism for the ZnS/CdS nanocomposites. The presented energy levels correspond to the band diagram of the 50-ZnS/CdS catalyst (E<sub>CB</sub> = conduction band level, E<sub>VB</sub> = valence band level, E<sub>F</sub> = Fermi level and DS = donor states).</p>
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12 pages, 4266 KiB  
Article
Photochemical Internalization with Fimaporfin: Enhanced Bleomycin Treatment for Head and Neck Cancer
by Paula Enzian and Ramtin Rahmanzadeh
Pharmaceutics 2023, 15(8), 2040; https://doi.org/10.3390/pharmaceutics15082040 - 28 Jul 2023
Cited by 2 | Viewed by 1606
Abstract
Head and neck squamous cell carcinoma (HNSCC) still represents the world’s sixth most common tumor entity, with increasing incidence. The reachability of light makes HNSCC suitable for light-based therapies such as Photochemical Internalization (PCI). The drug Bleomycin is cytotoxic and used as an [...] Read more.
Head and neck squamous cell carcinoma (HNSCC) still represents the world’s sixth most common tumor entity, with increasing incidence. The reachability of light makes HNSCC suitable for light-based therapies such as Photochemical Internalization (PCI). The drug Bleomycin is cytotoxic and used as an anti-tumor medication. Since Bleomycin is endocytosed as a relatively large molecule, part of it is degraded in lysosomes before reaching its intracellular target. The goal of our study was to improve the intracellular availability of Bleomycin with PCI. We investigate the intracellular delivery of Bleomycin after PCI with the photosensitizer Fimaporfin. A systematic variation of Bleomycin and Fimaporfin concentrations and light irradiation led to the pronounced cell death of HNSCC cells. After optimization, the same level of tumor cell death of 75% was reached with a 20-fold lower Bleomycin concentration. This would allow treatment of HNSCC with high local tumor cell death and reduce the side effects of Bleomycin, e.g., lung fibrosis, at the same time. This demonstrates the increased efficacy of the anti-tumor medication Bleomycin in combination with PCI. Full article
(This article belongs to the Special Issue Novel Regimens for Targeted Cancer Therapy)
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<p>(<b>a</b>) Absorption spectrum of Fimaporfin. (<b>b</b>) Fluorescence spectrum at 420 nm excitation.</p>
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<p>Fimaporfin without light irradiation shows no cytotoxicity against UT-SCC-5 cells. (<b>a</b>) MTT assay: 48 h after incubation of different Fimaporfin concentrations (0.1–0.5 µg/mL) without irradiation. (<b>b</b>) CFA: 12 days after incubation of different Fimaporfin concentrations (0.1–0.3 µg/mL) without light irradiation.</p>
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<p>12 days after incubation of Bleomycin the CFA assay showed high surviving fraction of UT-SCC-5 cells up to a concentration of 0.5 µM.</p>
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<p>CFA assay showed a survival rate of 93.14 ± 2.93% at a concentration of 0.2 µg/mL TPCS<sub>2a</sub> and an irradiation energy of 0.3 J/cm<sup>2</sup>. At higher irradiation energies, the survival rate decreased continuously.</p>
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<p>12 days after irradiation, CFA assay showed a high surviving fraction of UT-SCC-5 cells at a Bleomycin concentration of 0.1 µM at all three energies.</p>
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<p>CFA 12 days after irradiation with the combination of Fimaporfin and Bleomycin. (<b>a</b>) Setup using low irradiation energy of 0.3 J/cm<sup>2</sup> and Bleomycin in a concentration of 0.25 µM. (<b>b</b>) Setup with lower concentration of Bleomycin (0.1 µM) but an irradiation energy of 0.6 J/cm<sup>2</sup>. The two linked columns from the <span class="html-italic">t</span>-test analysis indicate the statistically significant difference (* <span class="html-italic">p</span> ≤ 0.05 significant; *** <span class="html-italic">p</span> ≤ 0.001 highly significant) in cell viability between the two samples.</p>
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<p>The monoclonal antibody TuBB-9-FITC can be delivered intracellularly with photochemical internalization using Fimaporfin. Microscopy images of TPCS<sub>2a</sub> and TuBB-9-FITC without and after irradiation. Irradiation took place at 420 nm and 0.25 J/cm<sup>2</sup>. Fimaporfin was used at a concentration of 0.1 µg/mL. Before irradiation, the antibody was mainly located in spots in the endosome (<b>upper row</b>). 30 min after irradiation, the antibody was visible next to the nucleoli (arrows, <b>middle row</b>). 24 h after irradiation, it can be detected in the nuclei (arrows, <b>lower row</b>). Scale bar: 25 µm.</p>
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16 pages, 35205 KiB  
Article
Dendritic Mesoporous Organosilica Nanoparticles with Photosensitizers for Cell Imaging, siRNA Delivery and Protein Loading
by Haneen Omar, Sara Jakimoska, Julia Guillot, Edreese Alsharaeh, Clarence Charnay, Frédérique Cunin, Aurélie Bessière, Jean-Olivier Durand, Laurence Raehm, Laure Lichon, Mélanie Onofre and Magali Gary-Bobo
Molecules 2023, 28(14), 5335; https://doi.org/10.3390/molecules28145335 - 11 Jul 2023
Cited by 1 | Viewed by 1880
Abstract
Dendritic mesoporous organosilica nanoparticles (DMON) are a new class of biodegradable nanoparticles suitable for biomolecule delivery. We studied the photochemical internalization (PCI) and photodynamic therapy (PDT) of DMON to investigate new ways for DMON to escape from the endosomes-lysosomes and deliver biomolecules into [...] Read more.
Dendritic mesoporous organosilica nanoparticles (DMON) are a new class of biodegradable nanoparticles suitable for biomolecule delivery. We studied the photochemical internalization (PCI) and photodynamic therapy (PDT) of DMON to investigate new ways for DMON to escape from the endosomes-lysosomes and deliver biomolecules into the cytoplasm of cells. We added photosensitizers in the framework of DMON and found that DMON were loaded with siRNA or FVIII factor protein. We made four formulations with four different photosensitizers. The photosensitizers allowed us to perform imaging of DMON in cancer cells, but the presence of the tetrasulfide bond in the framework of DMON quenched the formation of singlet oxygen. Fortunately, one formulation allowed us to efficiently deliver proapoptotic siRNA in MCF-7 cancer cells leading to 31% of cancer cell death, without irradiation. As for FVIII protein, it was loaded in two formulations with drug-loading capacities (DLC) up to 25%. In conclusion, DMON are versatile nanoparticles capable of loading siRNA and delivering it into cancer cells, and also loading FVIII protein with good DLC. Due to the presence of tetrasulfide, it was not possible to perform PDT or PCI. Full article
(This article belongs to the Collection Porous Materials)
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<p>(<b>A</b>) The tetraaminophenylporphyrin with four triethoxysilyl groups was used for the preparation of DMONPS1. (<b>B</b>) DMONPS1 as shown by TEM, the dendritic structure is visible. (<b>C</b>) UV-Vis spectra in EtOH of the silylated photosensitizer (PS1) and the corresponding DMONPS1; the photosensitizer is encapsulated inside the framework of DMONPS1, and the Soret and four Q bands are visible. (<b>D</b>) Nitrogen adsorption–desorption at 77 K (BET). Red desorption, black adsorption. Insert BJH adsorption (dV/dw) pore volume.</p>
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<p>(<b>A</b>) The monosilylated aminophenylporphyrin was used for the preparation of DMONPS2. (<b>B</b>) DMONPS2 as shown by TEM: the dendritic structure is visible, and the nanoparticles seem aggregated. (<b>C</b>) UV-Vis spectra in EtOH of the silylated photosensitizer(PS2) and the corresponding DMONPS2; the photosensitizer is encapsulated inside the framework of DMONPS2, and the Soret band is visible. (<b>D</b>) Nitrogen adsorption–desorption at 77 K (BET). Red desorption, black adsorption. Insert BJH adsorption (dV/dw) pore volume.</p>
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<p>(<b>A</b>) The monosilylated aminoporphyrin used for the preparation of DMONPS3. (<b>B</b>) DMONP3 as shown by TEM: the dendritic structure is visible. (<b>C</b>) UV-Vis spectra in EtOH of the silylated photosensitizer(PS3) and the corresponding DMONPS3; the photosensitizer is encapsulated inside the framework of DMONPS3, and the Soret band is visible. (<b>D</b>) Nitrogen adsorption–desorption at 77 K (BET). Red desorption, black adsorption. Insert BJH adsorption (dV/dw) pore volume.</p>
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<p>(<b>A</b>) The trisilylated chlorin e6 used for the preparation of DMONPS4. (<b>B</b>) DMONP4 as shown by TEM: the dendritic structure is visible. (<b>C</b>) UV-Vis spectra in EtOH of the silylated photosensitizer(PS4) and the corresponding DMONPS4; the photosensitizer is encapsulated inside the framework of DMONPS4, and the Soret and Q1 bands are visible. (<b>D</b>) Nitrogen adsorption–desorption at 77 K (BET). Red desorption, black adsorption. Insert BJH adsorption (dV/dw) pore volume.</p>
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<p>(<b>A</b>) FTIR of DMONPS1, DMONPS1-NH<sub>2</sub>, DMONPS1-Lys. (<b>B</b>) FTIR of DMONPS2, DMONPS2-NH<sub>2</sub>, DMONPS2-Lys (<b>C</b>) FTIR of DMONPS3, DMONPS3-NH<sub>2</sub>, DMONPS3-Lys. (<b>D</b>) FTIR of DMONPS4, DMONPS4-NH<sub>2</sub>, DMONPS4-Lys. All the materials showed the characteristic band at 1675 cm<sup>−1</sup>, corresponding to the amide I group.</p>
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<p>Confocal microscopy imaging of MCF-7 cancer cells incubated with DMONPS1-4, DMONPS1-4-NH<sub>2,</sub> or DMONPS1-4-Lys, for 24 h. ℷ<sub>excitation</sub> = 420 nm ℷ<sub>emission</sub> = 630–670 nm. Membranes were stained with a cell mask 15 min before observation. ℷ<sub>excitation</sub> = 561 nm ℷ<sub>emission</sub> = 565–629 nm.</p>
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<p>Cytotoxicity studies of MCF-7 cancer cells were performed through incubation with DMONPS1-4, DMONPS1-4-NH<sub>2,</sub> or DMONPS1-4-Lys, for 72 h. The cytotoxicity was monitored with the MTT assay. Curves presented are those of DMON loaded with (<b>A</b>) PS1, (<b>B</b>) PS2, (<b>C</b>) PS3 and (<b>D</b>) PS4.</p>
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<p>Agarose gel-retardation assay with DMONPS1-4-Lys, complexed with siRNA (negative control (A)), at different weight ratios ranging from 1/10 to 1/50. Electrophoresis was immediately performed after complex formation for 30 min at 37 °C.</p>
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<p>Anticancer effect of DMONPS1-4 complexed with siRNA inhibitor of apoptosis protein (IAP). MCF-7 cells were treated (or not) with free DMONPS1-4 (at 25 µg·mL<sup>−1</sup>) or DMONPS1-4 complexed with siRNA at a 1/15 ratio. The killing effect was monitored with the MTT assay. The red bar graphs highlighted the efficient nanoparticles for transfection.</p>
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<p>Calibration curve of FVIII at 2 mg/mL in PBS.</p>
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<p>Calibration curve of FVIII at 4 mg/mL in PBS.</p>
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<p>Functionalization of DMONPS1-4 with lysine amino acid (DMONPS1-4-Lys) in order to complex siRNA.</p>
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<p>Silylation of PS1.</p>
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<p>Silylation of PS2.</p>
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<p>Silylation of PS3.</p>
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<p>Silylation of PS4.</p>
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26 pages, 2702 KiB  
Review
Combinations of Photodynamic Therapy with Other Minimally Invasive Therapeutic Technologies against Cancer and Microbial Infections
by Sandile Phinda Songca
Int. J. Mol. Sci. 2023, 24(13), 10875; https://doi.org/10.3390/ijms241310875 - 29 Jun 2023
Cited by 14 | Viewed by 3343
Abstract
The rapid rise in research and development following the discovery of photodynamic therapy to establish novel photosensitizers and overcome the limitations of the technology soon after its clinical translation has given rise to a few significant milestones. These include several novel generations of [...] Read more.
The rapid rise in research and development following the discovery of photodynamic therapy to establish novel photosensitizers and overcome the limitations of the technology soon after its clinical translation has given rise to a few significant milestones. These include several novel generations of photosensitizers, the widening of the scope of applications, leveraging of the offerings of nanotechnology for greater efficacy, selectivity for the disease over host tissue and cells, the advent of combination therapies with other similarly minimally invasive therapeutic technologies, the use of stimulus-responsive delivery and disease targeting, and greater penetration depth of the activation energy. Brought together, all these milestones have contributed to the significant enhancement of what is still arguably a novel technology. Yet the major applications of photodynamic therapy still remain firmly located in neoplasms, from where most of the new innovations appear to launch to other areas, such as microbial, fungal, viral, acne, wet age-related macular degeneration, atherosclerosis, psoriasis, environmental sanitization, pest control, and dermatology. Three main value propositions of combinations of photodynamic therapy include the synergistic and additive enhancement of efficacy, the relatively low emergence of resistance and its rapid development as a targeted and high-precision therapy. Combinations with established methods such as chemotherapy and radiotherapy and demonstrated applications in mop-up surgery promise to enhance these top three clinical tools. From published in vitro and preclinical studies, clinical trials and applications, and postclinical case studies, seven combinations with photodynamic therapy have become prominent research interests because they are potentially easily applied, showing enhanced efficacy, and are rapidly translating to the clinic. These include combinations with chemotherapy, photothermal therapy, magnetic hyperthermia, cold plasma therapy, sonodynamic therapy, immunotherapy, and radiotherapy. Photochemical internalization is a critical mechanism for some combinations. Full article
(This article belongs to the Special Issue Photodynamic Therapy and Photodetection)
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<p>Mechanism of PDT shown by means of a Jablonski diagram.</p>
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<p>Classification of organic and inorganic nanoparticles. Reproduced from Spirescu et al. (2021) [<a href="#B107-ijms-24-10875" class="html-bibr">107</a>] and Greene et al. (2018) [<a href="#B108-ijms-24-10875" class="html-bibr">108</a>] under the creative commons attribution license 4.0.</p>
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<p>Chemical structures of the chemotherapy drugs ciprofloxacin, amikacin, and colistin.</p>
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<p>Chemical structures of the indium (II) porphyrin and phthalocyanine complexes.</p>
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<p>The synthesis and self-assembly of 3-(dimethylamino)phenoxy-functionalized zinc (II) phthalocyanine 6 to give a phthalocyanine nanoparticle. Adapted from Wang et al. (2022) [<a href="#B144-ijms-24-10875" class="html-bibr">144</a>].</p>
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<p>Schematic showing the principle of the anticancer immunotherapeutic technology known as checkpoint blockade.</p>
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17 pages, 6145 KiB  
Article
Quantifying the Potential Co-Benefit of Air Quality Improvement on Cultural Heritage in China
by Ximo Wang, Huimin Li, Yufei Wang and Xiaofan Zhao
Sustainability 2023, 15(11), 8709; https://doi.org/10.3390/su15118709 - 28 May 2023
Cited by 2 | Viewed by 1645
Abstract
Atmospheric pollutants can corrode heritage materials, especially stone, which can cause a great loss that goes far beyond the economic losses of the degraded materials. Over the past decades, conventional air pollutants have been slashed owing to clean air actions in China, which [...] Read more.
Atmospheric pollutants can corrode heritage materials, especially stone, which can cause a great loss that goes far beyond the economic losses of the degraded materials. Over the past decades, conventional air pollutants have been slashed owing to clean air actions in China, which produces a significant co-benefit for heritage conservation. However, the benefits may be offset by increases in the photochemical oxidants in smog, such as ozone, which damage heritage materials. This study employed dose–response functions to quantify the impacts of air pollutants on the surface recession of the limestone of heritage structures in China, and assessed the potential benefits of air quality improvement for heritage conservation. The results show that the annual recession rate decreased from 9.69 μmy−1 in 2006 to 6.71 μmy−1 in 2020, resulting in a 41.4% increase in the number of heritage sites meeting the ICP Materials (International Co-operative Program on Effects on Materials including Historic and Cultural Monuments) control target of 8 µmy−1 for 2020. The air quality improvement avoided CNY 136.2 million in heritage site maintenance costs. The recession risk shows distinct regional differences; the southern and northwest regions are still at a higher material corrosion level than the northern and Qinghai–Tibet regions. Nationwide, PM10 (particles with aerodynamic diameter less than 10 μm) is the main risk factor responsible for the surface recession of limestone material of heritage structures in China. The study provides evidence for the benefits of air quality improvement for heritage conservation. Further, the study also puts forward policy recommendations for heritage conservation, including assessing pollution risk, promoting heritage conservation through social sustainability, and implementing differentiated conservation strategies. Full article
(This article belongs to the Section Tourism, Culture, and Heritage)
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<p>Distribution of the national cultural heritage sites and the UNESCO World Heritage Sites in China.</p>
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<p>The major pollutant emissions in 2006–2020. Note: NO<sub>x</sub>, SO<sub>2</sub> data are from National Bureau of Statistics of China [<a href="#B83-sustainability-15-08709" class="html-bibr">83</a>]; PM<sub>10</sub> data in 2006–2015 are from Multi-resolution Emission Inventory for China (MEIC) [<a href="#B84-sustainability-15-08709" class="html-bibr">84</a>]; PM<sub>10</sub> data in 2016–2020 and average pH data are from the Ecological and Environmental Status Bulletin of China [<a href="#B74-sustainability-15-08709" class="html-bibr">74</a>].</p>
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<p>Estimated annual surface recession of limestone material of heritage sites in 2006–2020.</p>
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<p>The contribution of different pollutants to heritage recession. Note: The numbers above the bars represent the average contribution rates of different pollutants.</p>
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<p>The contributions of different pollutants for the 4 major regions in 2006–2010.</p>
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<p>The percentage of heritage sites in different ranges of surface recession in the three 5-year periods.</p>
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<p>The surface recession rate. The actual maintenance costs and the theoretical maintenance costs in 2006–2020.</p>
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