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Based on end-quenching experiments combined with conductivity, hardness testing, and microstructural characterization, the quenching sensitivity of the mechanical and corrosion properties of 7475 aluminum alloy was investigated. The study revealed that as the quenching rate decreased, both the mechanical properties and exfoliation corrosion resistance exhibited increased quenching sensitivity. With the quenching rate decreasing from 31.9 °C/s to 2.5 °C/s, the conductivity increased by 4.1%IACS, the hardness decreased by 31%, the exfoliation corrosion grade transitioned from EC to ED, and the maximum exfoliation corrosion depth increased from 237 μm to 508 μm. As the quenching rate decreased, the η phase sequentially precipitated at recrystallized grain boundaries (RGBs), E phase particles, and subgrain boundaries (SGBs), while the T phase primarily precipitated on E phase particles. Furthermore, the significant precipitation of η and T phases led to a notable reduction in the quantity of age-precipitated phases, an increase in their size, and poor coherency with the matrix, resulting in decreased mechanical properties and a higher quenching sensitivity of the mechanical performance. Meanwhile, with the reduction in quenching rate, the size and spacing of grain boundary precipitated phases increased, the Zn and Mg contents of grain boundary precipitated phases increased, and the Precipitation Free Zone (PFZ) widened, leading to decreased exfoliation corrosion resistance and higher quenching sensitivity of the exfoliation corrosion performance. [ABSTRACT FROM AUTHOR]

The influence of grain structure and quenching rates on the exfoliation corrosion (EXCO) susceptibility of 7085 alloy was studied using immersion tests, optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and scanning transmission electron microscopy (STEM). The results show that as the cooling rate decreases from 1048 °C/min to 129 °C/min; the size of grain boundary precipitates (GBPs); the width of precipitate-free zones (PFZ); and the content of Zn, Mg, and Cu in GBPs rise, leading to an increase in EXCO depth and consequently higher EXCO susceptibility. Meanwhile, there is a linear relationship between the average corrosion depth and the logarithm of the cooling rate. Corrosion cracks initiate at the grain boundaries (GBs) and primarily propagate along the HAGBs. In the bar grain (BG) sample at lower cooling rates, crack propagation along the sub-grain boundaries (SGBs) was observed. Compared to equiaxed grain (EG) samples, the elongated grain samples exhibit larger GBPs, a wider PFZ, and minor compositional differences in the GBPs, resulting in higher EXCO susceptibility. [ABSTRACT FROM AUTHOR]

Liquid phase deposition is a cost-effective and energy-efficient method for obtaining TiO2 films at low temperatures. This work demonstrates the use of a multifunctional template consisting of grafted gallic acid (GA) and hexamethylenediamine (HD) on a Ti substrate to regulate the deposition of TiO2 films. X-ray diffraction characterization shows that films deposited with the template have a more obvious anatase phase compared to direct deposition at 25 °C. The intensity of photoluminescence spectra also shows significant differences at 373.7 nm and 663.3 nm. Furthermore, electrochemical measurements indicate that TiO2 films adjusted by the template have excellent electrochemical conversion properties. This proposed method provides a new simple route for fabricating TiO2 films that are adjusted by GAHD templates, which may have good applications in the fields of semiconductor materials and biological materials. [ABSTRACT FROM AUTHOR]

Through isothermal hot compression experiments at various strain rates and temperatures, the thermal deformation behavior of Zn-2.0Cu-0.15Ti alloy is investigated. The Arrhenius-type model is utilized to forecast flow stress behavior. Results show that the Arrhenius-type model accurately reflects the flow behavior in the entire processing region. The dynamic material model (DMM) reveals that the optimal processing region for the hot processing of Zn-2.0Cu-0.15Ti alloy has a maximum efficiency of about 35%, in the temperatures range (493–543 K) and a strain rate range (0.01–0.1 s−1). Microstructure analysis demonstrates that the primary dynamic softening mechanism of Zn-2.0Cu-0.15Ti alloy after hot compression is significantly influenced by temperature and strain rate. At low temperature (423 K) and low strain rate (0.1 s−1), the interaction of dislocations is the primary mechanism for the softening Zn-2.0Cu-0.15Ti alloys. At a strain rate of 1 s−1, the primary mechanism changes to continuous dynamic recrystallization (CDRX). Discontinuous dynamic recrystallization (DDRX) occurs when Zn-2.0Cu-0.15Ti alloy is deformed under the conditions of 523 K/0.1 s−1, while twinning dynamic recrystallization (TDRX) and CDRX are observed when the strain rate is 10 s−1. [ABSTRACT FROM AUTHOR]

The development of hydrogels as wound dressings has gained considerable attention due to their promising ability to promote wound healing. However, in many cases of clinical relevance, repeated bacterial infection, which might obstruct wound healing, usually occurs due to the lack of antibacterial properties of these hydrogels. In this study, we fabricated a new class of self-healing hydrogel with enhanced antibacterial properties based on dodecyl quaternary ammonium salt (Q12)-modified carboxymethyl chitosan (Q12-CMC), aldehyde group- modified sodium alginate (ASA), Fe3+ via Schiff bases and coordination bonds (QAF hydrogels). The dynamic Schiff bases and coordination interactions conferred excellent self-healing abilities to the hydrogels, while the incorporation of dodecyl quaternary ammonium salt gave the hydrogels superior antibacterial properties. Additionally, the hydrogels displayed ideal hemocompatibility and cytocompatibility, crucial for wound healing. Our full-thickness skin wound studies demonstrated that QAF hydrogels could result in rapid wound healing with reduced inflammatory response, increased collagen disposition and improved vascularization. We anticipate that the proposed hydrogels, possessing both antibacterial and self-healing properties, will emerge as a highly desirable material for skin wound repair. [ABSTRACT FROM AUTHOR]

Background: In this study, we surveyed the prevalence of hepatitis B virus (HBV) surface antigen (HBsAg) and hepatitis C virus (HCV) antibody (anti-HCV) among inpatients with human immunodeficiency virus (HIV) infection and analyzed the correlated factors. Methods: We conducted a retrospective data collection of the HIV-infected inpatients in our hospital from January 2010 to December 2020. We utilized multivariate logistic regression to identify the correlated factors. Results: The proportion of patients screened for HBsAg was 81.8%, which increased from 66.7% in 2010 to 85.7% in 2020. The proportion of patients with anti-HCV screening was 73.9%, which increased from 58.3% in 2010 to 86.7% in 2020. The prevalence of HBsAg positivity was 10.9%, which decreased from 15.0% in the period of 2010–2015 to 9.0% during 2016–2020. Positive anti-HCV was identified in 4.1% of cases. Compared to 4.8% in the period of 2010–2015, there was a similar prevalence of anti-HCV at 3.1% during 2016–2020. Among the HBsAg-positive cases, HBV deoxyribonucleic acid was screened in 70.8% of cases. Among the anti-HCV positive cases, HCV ribonucleic acid (RNA) was screened in 90% of cases. Albumin < 30 g/L, thrombocytopenia and aspartate aminotransferase (AST) > 40 U/L were associated with HBsAg positivity. AST > 40 U/L and higher CD4-positive T lymphocyte counts were associated with HIV/HCV coinfection. Conclusions: The routine screening for both HBV and HCV among HIV-positive inpatients has been greatly improved in the past decade. However, screening for the complete HBV serological markers in HIV-positive inpatients and HCV genotyping among HCV RNA-positive cases leaves much to be desired. A concerted effort should be made to improve HBV vaccine compliance in the HIV-positive population and provide direct-acting antiviral therapies to HCV RNA-positive patients. [ABSTRACT FROM AUTHOR]

Background: Tobacco use is a global public health concern due to its association with a myriad of health hazards and costs. Previous studies have found that the disinhibiting influence of alcohol consumption may lead to an increase in tobacco use. In this study, we investigated why alcohol consumption is associated with tobacco use among older adults in Western China, and we attempted to explain the mechanisms that underlie the link between alcohol consumption and tobacco use. Methods: In this cross-sectional study, we employed a representative sample of 812 urban individuals aged 60 and older in 2017 in Western China. Results: We found that alcohol consumption (OR = 2.816, 95%CI: 1.770–4.479) was positively associated with tobacco use. Additionally, other factors, including gender (OR = 0.023, 95%CI: 0.009–0.060), age (OR = 0.758, 95%CI: 0.634–0.906), health literacy (OR = 0.977, 95%CI: 0.959–0.995) and functional impairment (OR = 0.871, 95%CI: 0.767–0.988) were also strongly related to tobacco use. Conclusions: Consistent with the results of existing studies, our findings demonstrated the disinhibiting influence of alcohol consumption on tobacco use, which confirmed the theoretical mechanisms that underlie the alcohol–tobacco link and implied the co-occurrence and co-use of alcohol and tobacco, which are used as "social lubricants" in the Chinese context. The importance of other factors related to tobacco use were also discussed. As the tobacco epidemic is combatted, joint interventions tailored to concurrent control over alcohol and tobacco need to be performed, and corresponding male-specific and age-specific health education and the reinforcement of health literacy must be considered as important priorities. [ABSTRACT FROM AUTHOR]

Transmission towers are prone to collapse under strong wind load, resulting in significant economic losses. In order to investigate the collapse mechanism and failure modes of the transmission tower under strong wind load and whether the wind vibration factor can greatly reflect the increasing effect of the fluctuating wind, the finite element method (FEM) is utilized to analyze the ultimate bearing capacity of a typical 220 kV transmission tower. The results show that the collapse of the tower under strong wind loads is usually due to the buckling of the leg members. When the reference wind speed is equal to 27 m/s, a small part of the main leg members reaches their yield strength, while the diagonal members are still in the elastic range, and the deformation of the transmission tower is unapparent at this wind speed. When reference wind speed is equal or greater than 30 m/s, the growing variety of main legs is totally into the plastic yield stage, and the overall deformation of this tower is visible. Therefore, the transmission tower is collapsed due to the large deformation caused by the elastic-plastic buckling of leg members. Based on the aforementioned study, a finite element model involving three transmission towers and four span transmission lines is established to analyze the dynamic response of the tower-line system below fluctuating wind. Results show that the wind-induced coefficients designed by current code not only notably satisfy the stress response of tower components subjected to fluctuating wind loads in the elastic phase but also accurately assess the collapse displacement of the transmission tower. The increasing effect of displacement on the top tower under fluctuating wind, unfortunately, could not considerably reply with the investigated factor, and the load-carrying capacity of the transmission tower in the plastic phase can be overestimated by static calculation results. [ABSTRACT FROM AUTHOR]

The microstructures, mechanical properties, and thermal conductivity (TC) of Al-2Fe-xCo (x = 0~0.8) alloys in as-cast, homogeneous annealed, and cool rolled states are systematically studied. Results indicate that appropriate Co modification (x ≤ 0.5) simultaneously improves the thermal and mechanical properties of as-cast Al-2Fe alloys. The improvement of TC is attributed to ameliorating the morphology of primary Al3Fe phases from needles to short rods and fine particles, which decreases the scattering probability of free electrons during the electronic transmission. However, further increasing the Co content (x = 0.8) decreases the TC due to the formation of a coarse plate-like Al2FeCo phase. Besides, the thermal conductivity of annealed Al-2Fe-xCo alloys is higher than that of as-cast alloys because of the elimination of lattice defects and spheroidization of Al3Fe phases. After cool rolling with 80 % deformation, thermal conductivity of alloys slightly increases due to the breaking down of Al2FeCo phases. The rolled Al-2Fe-0.3Co alloy exhibits the highest thermal conductivity, which is about 225 W/(m·K), approximately 11 % higher than the as-cast Al-2Fe sample. The ultimate tensile strength (UTS) and elongation (EL) of as-cast Al-2Fe-0.5Co (UTS: 138 MPa; EL: 22.0 %) are increased by 35 % and 69 %, respectively, compared with those of unmodified alloy (UTS: 102 MPa; EL: 13.0 %). [ABSTRACT FROM AUTHOR]

The quench sensitivity of 7085 aluminum alloy with different contents of the main alloying elements (Zn, Mg and Cu) was investigated using time-temperature-transformation (TTT) curves and end quenching experiments. Then, the quenching microstructure was analyzed using transmission electron microscopy. With increasing the contents of the main alloying elements, the transitions and nose temperatures of the TTT curves are obviously increased, while the incubation time of 0.5% η (MgZn2) phase precipitation content is decreased. In addition, as the contents of the main alloying elements decrease, the conductivity of the quenched samples is increased, but the hardness of the quenched samples is decreased. Moreover, the size and area fraction of the η phase are increased with increasing the contents of the main alloying elements. Based on the experimental results, the increase of Mg and Cu contents can decrease the stability of supersaturated solid solution and increase the lattice distortion energy, which can increase the quench sensitivity of 7085 aluminum alloy. [ABSTRACT FROM AUTHOR]

In this study, Fe-bearing Mg-3%Al alloys were inoculated by combining carbon with or without Ca. Both processes can significantly refine the grain size of Mg-3%Al alloys. The highest refining efficiency can be obtained by carbon combined with Ca. The synergistic grain refining efficiency can be attributed to the constitutional undercooling produced by the addition of Ca. Two kinds of carbon-containing nuclei with duplex-phase particles and cluster particles were observed in the carbon-inoculated alloys. A thermodynamic model was established to disclose the formation mechanisms of the duplex-phase particles and Al4C3 cluster particles. This thermodynamic model is based on the change of Gibbs free energy for the formation of these two kinds of particles. The calculated results show that these two particles can form spontaneously, since the change of Gibbs free energy is negative. However, the Gibbs free change of the duplex-phase particle is more negative than the Al4C3 cluster particle. This indicates that the adsorption process is more spontaneous than the cluster process, and tiny Al4C3 particles are preferred to form duplex-phase particle, rather than gathering to form an Al4C3 cluster particle. In addition, the addition of Ca can reduce the interfacial energy between the Al4C3 phase and the Al–Fe phase and promote the formation of duplex-phase particles. [ABSTRACT FROM AUTHOR]

To evaluate the influence of transition metal substituents on the characteristics of CH3NH3PbI3/TiO2, we investigated the geometrical and electronic properties of transition metal-substituted CH3NH3PbI3/TiO2 by first-principles calculations. The results suggested that the substitution of Ti4+ at the five-fold coordinated (Ti5c) sites by transition metals is energetically favored. The substituted interface has enhanced visible light sensitivity and photoelectrocatalytic activity by reducing the transition energies. The transition metal substitution can effectively tune the band gap of the interface, which significantly improves the photo-reactivity. The substituted systems are expected to be more efficient in separating the photo-generated electrons-holes and active in the visible spectrum. [ABSTRACT FROM AUTHOR]

The microstructures, mechanical properties, and thermal conductivity (TC) of Al-2Fe- x Co ( x = 0~0.8) alloys in as-cast, homogeneous annealed, and cool rolled states are systematically studied. Results indicate that appropriate Co modification ( x ≤ 0.5) simultaneously improves the thermal and mechanical properties of as-cast Al-2Fe alloys. The improvement of TC is attributed to ameliorating the morphology of primary Al 3 Fe phases from needles to short rods and fine particles, which decreases the scattering probability of free electrons during the electronic transmission. However, further increasing the Co content ( x = 0.8) decreases the TC due to the formation of a coarse plate-like Al 2 FeCo phase. Besides, the thermal conductivity of annealed Al-2Fe- x Co alloys is higher than that of as-cast alloys because of the elimination of lattice defects and spheroidization of Al 3 Fe phases. After cool rolling with 80 % deformation, thermal conductivity of alloys slightly increases due to the breaking down of Al 2 FeCo phases. The rolled Al-2Fe-0.3Co alloy exhibits the highest thermal conductivity, which is about 225 W/(m·K), approximately 11 % higher than the as-cast Al-2Fe sample. The ultimate tensile strength (UTS) and elongation (EL) of as-cast Al-2Fe-0.5Co (UTS: 138 MPa; EL: 22.0 %) are increased by 35 % and 69 %, respectively, compared with those of unmodified alloy (UTS: 102 MPa; EL: 13.0 %).