Abstract
HIV-1 drug resistance can compromise the effectiveness of antiretroviral therapy (ART). A survey of pretreatment HIV-1 drug resistance (PDR) was conducted in Lincang Prefecture of Yunnan ...Province. From 372 people living with HIV/AIDS initiating ART for the first time during 2017–2018, 322
pol
sequences were obtained, of which 11 HIV-1 strain types were detected. CRF08_BC (70.2%, 226/322) was the predominant strain, followed by URF strains (10.6%, 34/322). Drug resistance mutations (DRMs) were detected among 34.2% (110/322) of the participants. E138A/G/K/R (14.3%, 46/322) and V179E/D/T (13.7%, 47/322) were the predominant DRMs. Specifically, E138 mutations commonly occurred in CRF08_BC (19.9%, 45/226). Among the DRMs detected, some independently conferred resistance, such as K65R (1.6%, 5/322), Y188C/F/L (0.9%, 3/322), K103N (0.6%, 2/322) and G190A (0.3%, 1/322), which conferred high-level resistance. The prevalence of PDR was 7.5% (95% CI: 4.6–10.3%) and the prevalence of non-nucleotide reverse transcriptase inhibitor (NNRTI) resistance was 5.0% (95% CI: 2.6–7.4%), which is below the threshold (⩾10%) of initiating a public health response. In conclusion, HIV-1 genetic diversity and an overall moderate level of PDR prevalence were found in western Yunnan. PDR surveillance should be continually performed to decide whether a public health response to NNRTI resistance should be initiated.
Abstract
The development of the fifth-generation mobile communication technology (5G) puts forward higher requirements for radio frequency (RF) filters. Due to its higher frequency and larger ...bandwidth, bulk acoustic wave (BAW) filter will become the mainstream RF filter solution. Scandium doped aluminium nitride (AlScN) piezoelectric film has attracted much attention due to its excellent piezoelectric response coefficients and electromechanical coupling coefficients. The doped Sc concentration will directly affect the piezoelectric coefficient and electromechanical coupling coefficient of the film. The most common technique for producing AlScN thin films is magnetron sputtering of targets made of Al-Sc alloy. However, with the increase of Sc content, the solid-liquid solidification interval, the number of intermetallic compounds, and the brittleness of the material will all increase significantly. Additionally, it will result in component macro-segregation, uneven phase distribution, and poor processing deformability. Therefore, it is extremely difficult to manufacture and process Al-Sc alloy targets. The mainstream processes for preparing Al-Sc alloy targets are divided into direct reaction method and powder metallurgy method. This paper reviews the research progress in manufacturing and processing of Al-Sc alloy targets.
Density functional theory calculations were carried out to examine the mechanism of ethanol decomposition on the Rh(211) surface. We found that there are two possible decomposition pathways: (1) ...CH3CH2OH → CH3CHOH → CH3COH → CH3CO → CH3 + CO → CH2 + CO → CH + CO → C + CO and (2) CH3CH2OH → CH3CHOH → CH3COH → CH2COH → CHCOH → CHCO → CH + CO → C + CO. Both pathways have a common intermediate of CH3COH, and the key step is the formation of CH3CHOH species. According to our calculations, the mechanism of ethanol decomposition on Rh(211) is totally different from that on Rh(111): the reaction proceeds via CH3COH rather than an oxametallacycle species (−CH2CH2O– for Rh(111)), which implies that the decomposition process is structure sensitive. Further analyses on electronic structures revealed that the preference of the initial Cα–H path is mainly due to the significant reduction of d-electron energy in the presence of the transition state (TS) complex, which may stabilize the TS–surface system. The present work first provides a clear picture for ethanol decomposition on stepped Rh(211), which is an important first step to completely understand the more complicated reactions, like ethanol steam reforming and electrooxidation.
Ethanol dry reformation (EDR) is a chemical process for syngas production, which consumes a greenhouse gas and reduces carbon footprint. We present a mechanistic study of EDR over Rh catalyst based ...on density functional theory (DFT) calculations and microkinetic analysis. Our results show that both the initial decomposition of C2H5OH and the later C–O bond formation are crucial steps on the reaction free energy landscape. The microkinetic model suggests that the α-dehydrogenation of ethanol is the rate-determining step, and the calculated reaction rate (r H2 ) is 8.23 × 103 s–1. Moreover, factors behind catalyst deactivation were investigated and potential solutions were explored from both theoretical and experimental aspects. The results indicate that additional H2 could potentially mitigate catalyst deactivation by methanation of coke deposited on the catalyst. These computational and experimental efforts further the understanding of the complicated catalytic process and inspire the rational design of EDR catalysts.
Collapse accidents of deep excavations occurred frequently in soft soil areas. In this paper, a deep excavation failure case caused by inappropriate strut removal before casting floor slabs is ...introduced, and the finite difference method was used to investigate the progressive failure mechanism and learn some lessons. The internal forces and damage states of the structure members in the retaining system after the inappropriate strut removal were analyzed to identify the progressive failure path. The progressive collapse phenomenon in the numerical simulation was similar to that in the case. Local inappropriate strut removal led to internal force redistribution in the remaining system, and the stress patterns in structural components would not be conform with the design patterns and cause the structural components to fail progressively. The failure sequence in this case was found to be: kingposts, capping beam and waler beam, strut and retaining piles. At last, the retaining piles became cantilevered and were broken by bending moment and led to the collapse of the excavation. In addition, different strut removal sequences would cause slightly different progressive failure paths. To evaluate the progressive collapse resistance capacity, evaluation methods that can measure the extent of load transfer and robustness of the retaining system were proposed. For excavation retained by propped piles, increasing the load transmission paths of the retaining system, such as adding diagonals to horizontal strut system reasonably, can increase the robustness to resist the progressive collapse.
Handy Plant Efficiency Analyser (Handy PEA) provides a method for the high-throughput screening of photosynthetic germplasm. However, the large number of chlorophyll a fluorescence parameters (CFPs) ...from PEA and the inconsistency of CFP applications among studies greatly limit the accuracy of photosynthesis analyses. In this study, all 53 CFPs of 186 upland cotton cultivars (strains) were measured at 12:00 and 17:00 h. Thirty-two CFPs were selected according to biological importance, and the CFP relationships were determined. Differences in the response ability of cotton cultivars (strains) to high light intensity stress were demonstrated by the distribution of CFPs. Furthermore, the classification and evaluation of photosynthetic characteristics of cotton cultivars (strains) were carried out by Principal Component Analysis and Cluster Analysis. Finally, ten cotton cultivars (strains) with good photosynthetic performance were selected. This study provides a high-throughput method how to identify cotton germplasm resources with high photosynthetic efficiency.
The electronic structures and magnetic properties of V2ReZ (Z=B, Al, Ga, In, Si, Ge, Sn, Sb) compounds with CuHg2Ti-type structure have been investigated. V2ReZ (Z=Al, Ga, In) compounds are predicted ...to be half-metallic ferrimagnets at their equilibrium lattice parameter. The half-metallicity can be achieved by expanding the lattice parameter for V2ReB compound. The half-metallicity still holds when the lattice expansion, contraction or tetragonal deformation occurs for V2ReZ (Z=B, Al, Ga, In). The energy gap between the eg and t2g states is the half-metallic gap for V2ReZ (Z=B, Al, Ga, In) compounds, which causes the compounds to not follow the Mt=Zt−24 rule but follow an Mt=Zt−18 rule instead. The influences of lattice change and different Z atoms on half-metallicity and magnetic properties are also discussed.
•A series of new half-metallic ferrimagnets were reported.•The high spin-polarization can be held in a quite wide range of lattice.•A different Slater–Pauling rule and explanations on the origin of half-metallic gap were shown.
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