Search Results (349)

With the evolution of the Internet, artificial intelligence, and other technologies, the era of the digital economy has quietly emerged. The digital economy’s growth is a major trend, and China is dedicated to building data power and strengthening foreign trade competitiveness (FTC). As an essential strategic region, Hunan Province should grasp the opportunities of the digital economy and constantly develop and increase its competitiveness. This research will explore the effect of Digital economy (DIG) on the FTC of Hunan Province. The study collected data from the region from 2013 to 2022 and Stata 17 software was applied to obtain the research outcomes. The findings indicate that DIG can significantly enhance the development of FTC in Hunan Province. This result remains consistent even after conducting robustness tests, showing its reliability. Furthermore, the positive impact is even more pronounced in urban agglomerations of major cities and larger areas. The paper’s main innovation lies in its focus on the Hunan Province region, which holds significant regional importance and plays a key role in enhancing China’s FTC. Full article

This study examines the crack resistance of basalt-fiber-reinforced concrete (BFRC) materials subjected to freeze–thaw cycles (FTCs). We utilized a φ50 mm Split Hopkinson Pressure Bar (SHPB) apparatus alongside numerical simulations to carry out impact compression tests at a velocity of 5 m/s on BFRC specimens that experienced 0, 10, 20, and 30 FTCs. Additionally, we investigated the effects of basalt fiber (BF) orientation position and length on stress intensity factors. The results reveal that with an increasing number of FTCs, the dynamic crack propagation speed of BFRC with a prefabricated crack inclined at 0° rises from 311.84 m/s to 449.92 m/s, while its pure I fracture toughness decreases from 0.6266 MPa·m^0.5 to 0.4902 MPa·m^0.5. For BFRC specimens with a prefabricated crack inclination of 15°, the dynamic crack propagation speed increases from 305.81 m/s to 490.02 m/s, accompanied by a reduction in mode I fracture toughness from 0.3901 MPa·m^0.5 to 0.2867 MPa·m^0.5 and mode II fracture toughness from 0.6266 MPa·m^0.5 to 0.4902 MPa·m^0.5. In the case of a prefabricated crack inclination of 28.89°, the dynamic crack propagation speed rises from 436.10 m/s to 494.28 m/s, while its pure mode II fracture toughness decreases from 1.1427 MPa·m^0.5 to 0.7797 MPa·m^0.5. Numerical simulations indicate that fibers positioned ahead of the crack tip—especially those that are longer, located closer to the crack tip, and oriented more perpendicularly—significantly reduce the mode I stress intensity factor. However, these fibers have a minimal impact on reducing the mode II stress intensity factor. The study qualitatively and quantitatively analyzes the crack resistance of basalt-fiber-reinforced concrete in relation to freeze–thaw cycles and the fibers ahead of the crack tip, offering insights into the fiber reinforcement effects within the concrete matrix. Full article

Efavirenz (EFV) causes neuropsychiatric effects such as anxiety, depression, and suicidal thoughts in people with HIV (PWH). Depressive disorders have been associated with the Tryptophan hydroxylase type 2 (TPH2) gene. Objectives: This study determines the genotypes and allelic frequencies of three TPH2 single nucleotide polymorphisms (SNPs) in a Mexican cohort of HIV-1 treatment-naïve-patients and the severity of depressive symptoms at baseline and after a four-week clinical follow-up of antiretroviral treatment. Methods: In a pilot prospective study, eighty-one antiretroviral treatment-naïve patients were recruited from the Infectious Disease Hospital, National Medical Center “La Raza”, in Mexico City. Of these, 39 were treated using a set-dose combination regimen of tenofovir disoproxil fumarate/emtricitabine (TDF/FTC) plus EFV and 42 were treated with TDF/FTC plus atazanavir/ritonavir (ATV/r), and fifty-nine control volunteers. Genomic DNA was obtained from peripheral blood mononuclear cells. All DNA samples underwent qPCR utilizing TaqMan probes for the three TPH2 SNPs studied. All participants underwent evaluation utilizing the Beck Depression Inventory. Results: Of the three SNPs examined, none exhibited any notable differences in the distribution of the alleles between the groups; nevertheless, rs4570625 TT and rs1386493 GG presented a twofold and fivefold greater risk of severe depression in PWH, respectively, independently of the treatment. Among PWH, those treated with EFV experienced severe depression at a higher rate of 90.4% after four weeks, compared to 87.5% in those treated with ATV/r. Conclusions: High rates of severe depression were identified in PWH, who presented the rs4570625 TT and rs1386493 GG polymorphic variants. Depression increased after four weeks of treatment and was higher with EFV than ATV/r. It is crucial to emphasize the necessity of conducting psychiatric monitoring for every patient with HIV and administering prompt antidepressant treatment. Full article

Flowering is initiated in response to environmental cues, with the photoperiod and ambient temperature being the main ones. The regulatory pathways underlying floral transition are well studied in Arabidopsis thaliana but remain largely unknown in legumes. Here, we first applied an in silico approach to infer the regulatory inputs of four FT-like genes of the narrow-leafed lupin Lupinus angustifolius. We studied the roles of FTc1, FTc2, FTa1, and FTa2 in the activation of meristem identity gene AGL8 in response to 8 h and 16 h photoperiods, vernalization, and the circadian rhythm. We developed a set of regression models of AGL8 regulation by the FT-like genes and fitted these models to the recently published gene expression data. The importance of the input from each FT-like gene or their combinations was estimated by comparing the performance of models with one or few FT-like genes turned off, thereby simulating loss-of-function mutations that were yet unavailable in L. angustifolius. Our results suggested that in the early flowering Ku line and intermediate Pal line, the FTc1 gene played a major role in floral transition; however, it acted through different mechanisms under short and long days. Turning off the regulatory input of FTc1 resulted in substantial changes in AGL8 expression associated with vernalization sensitivity and the circadian rhythm. In the wild ku line, we found that both FTc1 and FTa1 genes had an essential role under long days, which was associated with the vernalization response. These results could be applied both for setting up new experiments and for data analysis using the proposed modeling approach. Full article

Concrete structures in cold regions are affected by freeze–thaw cycles (FTCs) and carbonation, which lead to the premature failure of concrete structures. The carbonation depth, relative dynamic elastic modulus (RDEM), compressive strength, porosity, and pore size distribution of concrete under FTC conditions were tested through an accelerated carbonation experiment to study the carbonation performance evolution. The freeze–thaw effect mechanism on concrete carbonation was further analyzed via the obtained relationship between carbonation depth and pore structure. The results showed that the FTC, as a powerful source of concrete damage, accelerates the carbonation reaction. Carbonization products fill some microcracks caused by the freeze–thaw process, improve the compressive strength and dynamic elastic modulus, and alleviate the damage to concrete caused by the FTC. After carbonization under freeze–thaw damage conditions, the content of macropores with d > 1000 nm decreases, while the content of transition pores with d ≤ 10 nm increases, which is the direct reason for the decrease in porosity and the improvement in strength. Therefore, the carbonation durability of concrete under freeze–thaw conditions can be improved by controlling the content of macropores with d > 1000 nm and increasing the content of transition pores with a pore size of 10 nm ≤ d < 100 nm. In addition, the relationship between carbonation depth and pore structure under freeze–thaw conditions was established, and the research results can provide a reference for the study of the carbonation performance of concrete under freeze–thaw conditions. Full article

Background: With advances in antiretroviral therapy for HIV treatment, newer drug combinations provide improved efficacy, safety, and compliance. This study evaluates switching to a regimen of doravirine (DOR), tenofovir disoproxil fumarate (TDF), and lamivudine (3TC) in a cohort of people living with HIV (PLWH). Methods: this Italian retrospective study included 426 PLWH who switched from rilpivirine (RPV)/TDF/emtricitabine (FTC) to DOR/3TC/TDF. The analysis focused on treatment effectiveness, safety, and metabolic and renal markers. Results: this study reports a treatment failure (defined as virological failure or discontinuation of the regimen) rate of 2.34% (95% confidence interval, 1.28–4.50%), with significant improvement in CD4 counts (+49.93 cells/µL, p < 0.001). Notably, the switch to DOR/3TC/TDF did not result in adverse metabolic effects or significant changes in renal function. Analysis of lipid profiles showed stabilization in the majority of PLWH. Conclusions: this study indicates that switching to a DOR/3TC/TDF from RPV/TDF/FTC is an effective and well-tolerated option for PLWH, with benefits in terms of maintaining viral suppression, CD4 count recovery, and metabolic health, without evidence of renal impairment. These results support the continued use of DOR/3TC/TDF as part of HIV treatment strategies and highlight the need for ongoing research to refine ART regimens for different populations. Full article

Background: Follicular thyroid carcinoma (FTC) is categorized into three groups: minimally invasive FTC (MIFTC), encapsulated angioinvasive FTC (EAIFTC), and widely invasive FTC (WIFTC). FTC is the second most common type of thyroid tumor, though it remains relatively rare in the general population. This study aimed to examine the prognosis and prognostic factors in patients with follicular thyroid carcinoma. Methods: Data were obtained from a tertiary referral center for 130 FTC patients, covering the period from 1995 to 2020. Clinical data included demographic characteristics, tumor features, type of surgery, tumor recurrence, and vital status. Descriptive statistical methods, Kaplan–Meier survival curves, and Cox proportional hazard regression were used for statistical analysis to identify independent predictors. Results: Distant metastases occurred in 12 patients during the follow-up period. The 5-year, 10-year, 15-year, and 20-year cancer-specific survival (CSS) rates were 98.1%, 92.3%, 83.5%, and 79.8%, respectively. Independent unfavorable prognostic factors for CSS included widely invasive tumor type (hazard ratio [HR] 3.63, 95% CI 1.29–10.18), multifocality (HR 6.7, 95% CI 1.37–32.72), and presence of distant metastases (HR 2.29, 95% CI 1.08–4.84). When disease-free interval (DFI) was considered, the 5-year, 10-year, 15-year, and 20-year rates were 92.3%, 85.3%, 82.0%, and 76.6%, respectively. Independent unfavorable prognostic factors for DFI were widely invasive tumor type (HR 2.53, 95% CI 1.02–6.28) and tumor multifocality (HR 7.69, 95% CI 1.07–55.17). Conclusions: The 10-year survival rate for patients with FTC is relatively favorable. Factors associated with poorer prognosis include the presence of distant metastases, WIFTC, and multifocality. Factors linked to disease recurrence are WIFTC and multifocality. Full article

This paper presents the design of a fault-tolerant control system based on fault estimation, aimed at enhancing the sustainability and efficiency of a wind energy conversion system using a doubly-fed induction generator. The control architecture comprises a rotor-side converter (RSC) and a grid-side converter (GSC). The RSC is responsible for regulating both active and reactive power, and its model incorporates two linear subsystem representations. A fault-tolerant control (FTC) scheme is developed using a state-feedback controller; this controller is applied to regulate stator and rotor currents. Additionally, for comparison purposes, Proportional–Integral (PI) and Sliding-Mode Controllers (SMCs) are designed to analyze the performance of each controller. Furthermore, a proportional integral observer is employed in the proposed fault-tolerant scheme for actuator fault estimation. Fault detection is achieved by comparing the fault estimation signal with a predefined threshold. The main contribution of this work is the design and validation of a comprehensive active FTC scheme that enhances system reliability and sustainability. It also includes a performance analysis comparing three controllers (PI, SMC, and state-feedback) applied to the RSC. These controllers are evaluated for their ability to regulate active and reactive power in a wind energy conversion system under conditions of non-constant actuator faults. Full article

The increasing use of lithium-containing materials highlights the urgent need for their recycling to preserve resources and protect the environment. Lithium-containing slags, produced during the pyrometallurgical process in lithium-ion battery recycling, represent an essential resource for lithium recovery efforts. While multiple methods for lithium recycling exist, it is crucial to emphasize environmentally sustainable approaches. This study employs dry forced triboelectrification (FTC) to recover valuable components from slag powder, commonly known as engineered artificial minerals (EnAMs). The FTC method is used to change the charge of the target material and achieve a neutral state while other materials remain charged. The downstream electrostatic separator enables the charged particles to be separated from the target material, which in this study is lithium aluminate. The results show that the method is effective, and lithium aluminate can be successfully enriched. Full article

Islatravir (ISL) is the first-in-class nucleoside reverse transcriptase translocation inhibitor (NRTtI) with novel modes of action. Data on ISL resistance are currently limited, particularly to HIV-1 non-B subtypes. This study aimed to assess prevalent nucleos(t)ide reverse transcriptase inhibitor (NRTI)-resistant mutations in HIV-1 subtype C for their phenotypic resistance to ISL. Prevalent single and combinations of NRTI-resistant mutations were selected from a routine HIV-1 genotypic drug resistance testing database and introduced into HIV-1 subtype C-like pseudoviruses, which were then tested for ISL susceptibility. Single NRTI-resistant mutations were susceptible or showed only a low level of resistance to ISL. This included thymidine analogue mutations (TAMs, i.e., M41L, D67N, K70R, T215FY, and K219EQ) and non-TAMs (i.e., A62V, K65R, K70ET, L74IV, A114S, Y115F, and M184V). Combinations of M184V with one or more additional NRTI-resistant mutations generally displayed reduced ISL susceptibilities. This was more prominent for combinations that included M184V+TAMs, and particularly M184V+TAM-2 mutations. Combinations that included M184V+K65R did not impact significantly on ISL susceptibility. Our study suggests that ISL would be effective in treating people living with HIV (PLWH) failing tenofovir disoproxil fumarate (TDF)/lamivudine (3TC) or TDF/emtricitabine (FTC)-containing regimens, but would be less effective in PLH failing zidovudine (AZT) with 3TC or FTC-containing regimens. Full article

Two decades ago, Ngai and Wang introduced a well-known finite type condition (FTC) on the self-similar iterated function system (IFS) with overlaps and used it to calculate the Hausdorff dimension of self-similar sets. In this paper, inspired by Ngai and Wang’s idea, we define a new FTC on self-affine IFS and obtain an analogous formula on the generalized dimensions of self-affine sets. The generalized dimensions raised by He and Lau are used to estimate the Hausdorff dimension of self-affine sets. Full article

This paper investigated the tracking problem of mixed ${\mathcal{H}}_{\infty }$ and $L_2-L_{\infty }$ adaptive fault-tolerant control (FTC) for continuous-time interval type-2 fuzzy systems (IT2FSs). For the membership function mismatch and uncertainty between the modules of the nonlinear system, the IT2 fuzzy model is applied to linearly approximate it. The observer can sensitively estimate the system state, and the adaptive fault estimation functions can estimate adaptively the fault signals, which enables the designed adaptive FTC scheme to ensure the asymptotic stability of the closed-loop control system and achieve the desired mixed ${\mathcal{H}}_{\infty }$ and $L_2-L_{\infty }$ tracking performance. The designed adaptive control law can achieve the purpose of dynamic compensation for faults and disturbances, and the introduced lemmas further reduce the design conservatism by adjusting the slack parameters and matrices. Finally, a mass-spring-damping system is used to illustrate the effectiveness of the designed method. Full article

Fault detection and diagnosis (FDD) methods and fault-tolerant control (FTC) have been the focus of intensive research across various fields to ensure safe operation, reduce costs, and optimize maintenance tasks. Unmanned aerial vehicles (UAVs), particularly quadcopters or quadrotors, are often prone to faults in sensors and actuators due to their complex dynamics and exposure to various external uncertainties. In this context, this work implements different FDD approaches based on the Kalman filter (KF) for fault estimation to achieve FTC of the quadcopter, considering different faults with nonlinear behaviors and the possibility of simultaneous occurrences in actuators and sensors. Three KF approaches are considered in the analysis: linear KF, extended KF (EKF), and unscented KF (UKF), along with three-stage and adaptive variations of the KF. FDD methods, especially the adaptive filter, could enhance fault estimation performance in the scenarios considered. This led to a significant improvement in the safety and reliability of the quadcopter through the FTC architecture, as the system, which previously became unstable in the presence of faults, could maintain stable operation when subjected to uncertainties. Full article

This paper presents an innovative approach that integrates a fixed-time control (FTC) algorithm with an improved sparrow search algorithm (ISSA) to enhance the trajectory tracking accuracy of a two-degree-of-freedom (two-DOF) robotic arm. The FTC algorithm, which incorporates barrier Lyapunov function (BLF) and adaptive neural network strategies, ensures rapid convergence, effective vibration suppression, and the robust handling of system uncertainties and input saturation. The ISSA, inspired by the foraging behavior of sparrows, improves search efficiency through dynamic weight adjustments and chaotic mapping, balancing global and local search capabilities. By optimizing control parameters, ISSA minimizes tracking errors. Simulation results demonstrate that the combined FTC and ISSA approach significantly reduces tracking errors and improves response speed compared to the use of FTC alone, underscoring its potential for achieving high-precision control in robotic arms and offering a promising direction for precise robotic control applications. Full article

This study employs secondary ion mass spectrometry (SIMS) to investigate the diffusion behavior of hydrogen and carbon in a Cd_xZn_1−xO:Eu multilayer at different annealing temperatures (500–900 °C). The SIMS results reveal a significant out-diffusion of these elements toward the surface and diffusion to the interface region. The diffusion flow rates are asymmetric and favor the interface direction. The depth profiles of diffused elements are fitted using the forward timecentered space (FTCS) iteration method. The activation energies are determined to be 0.35 ± 0.06 eV for hydrogen and 0.33 ± 0.09 eV for carbon, suggesting an interstitial mechanism in Cd_xZn_1−xO. The results indicate that increasing the annealing temperatures leads to a significant decrease in impurity concentrations. Full article