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To optimise patients’ outcomes and gain insight into transmitted drug resistance (TDR) among human immunodeficiency virus (HIV)-1 treatment-naive patients in Beijing, the prevalence of TDR was assessed. Demographic and clinical data of 1241 treatment-naive patients diagnosed between April 2014 and February 2015 were collected. TDR was defined using the Stanford University HIV drug resistance mutations database. The risk factors were evaluated by multi-logistic regression analysis. Among 932 successfully amplified cases, most were male (96.78%) and infected through men having sex with men (91.74%). Genotype were CRF01_AE (56.44%), B (20.60%), CRF07_BC (19.96%), C (1.61%) and other genotypes (1.39%). The overall prevalence of TDR was 6.12%. Most frequent mutations occurred in non-nucleoside reverse transcriptase inhibitors (NNRTIs) (3.11%), followed by protease inhibitors (PIs) (2.25%) and nucleoside reverse transcriptase inhibitors (NRTIs) (1.32%). Furthermore, HIV-1 genotype was associated with high risk of resistance, in which genotype C and other genotype may have higher risk for resistance. The prevalence among treatment-naive patients in Beijing was low. Resistance to NNRTIs was higher than with PIs or NRTIs. Continuous monitoring of regional levels of HIV-1 TDRs would contribute to improve treatment outcomes and prevent failures.
As the energy spread of intense pulsed electron beams (IPEB) strongly influences the irradiation effects, it has been of great importance to characterize the IPEB energy spectrum. With the combination of Child–Langmuir law and Monte Carlo simulation, the IPEB energy spectrum has been obtained in this work by transformation from the accelerating voltage applied to the diode. To verify the accuracy of this simple algorithm, a magnetic spectrometer with an imaging plate was designed to test the IPEB energy spectrum. The measurement was completed with IPEB generated by explosive emission electron diode, the pulse duration, maximum electron energy, total beam current being 80 ns, 450 keV, and 1 kA, respectively. The results verified the reliability of the above analysis method for energy spectrum, which can avoid intercepting the beam, and at the same time significantly improved the energy resolution. Some calculation and experimental details are discussed in this paper.
Inhomogeneity may lead to premature failure and operationally determines the lifetime estimation of thick weld joints. Considerable novelty of this paper was the achievement of the microstructural and mechanical inhomogeneity, especially along the thickness direction, in the narrow-gap weld seam of thick gas metal arc (GMA) welded Al–Zn–Mg alloy plates. The microstructure of the weld seam was investigated by means of optical metallography, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectrum (EDS), after which the phase composition was ascertained according to the x-ray diffraction (XRD) analysis and selected area diffraction analysis by TEM (TEM-SAD). The generation of intergranular short rod-shaped MgZn2 particles changed the distribution of precipitates on the grain boundary with intragranular ellipsoidal MgZn2 particles simultaneously formed as the strengthening phase, which rendered preferable mechanical performances to the bottom layer of the weld seam. The above conclusion was farther affirmed by micro fractography and EDS test results on the fractured surface of the tensile samples. In addition, the effect of following weld passes on the microstructure and micro hardness profile of the finished weld pass was investigated.
In the experiments reported here, we used the female ladybird Coccinella septempunctata L. as a model to identify diapause-associated proteins using proteomics technology. Our results indicated that protein expression patterns of diapausing and nondiapausing individuals were highly differentiated. A total of 58 spots showed significant differences in abundance (Ratio > 2 and P < 0.05) according to two-dimensional electrophoresis and GE Image Scanner III analysis. Sixteen protein spots were further investigated using mass spectrometry. Eight proteins were characterized, including chaperones and proteins involved in glucose metabolism, lipid metabolism, and the tricarboxylic acid cycle. Among these proteins, five proteins were upregulated in diapausing female adults, including a chaperone (Symbionin symL), malate dehydrogenase (putative), two proteins linked to lipid metabolism (unknown and conserved hypothetical protein) and phosphoglyceromutase (partial). By contrast, isocitrate dehydrogenase (RH49423p), fumarylacetoacetate hydrolase (AGAP001942-PA), and a putative medium chain acyl-CoA dehydrogenase were downregulated. These results contribute to the understanding of diapause mechanisms of the ladybird C. septempunctata and may suggest methods for improving the application of this natural enemy insect.
Reconstruction of a complete Quaternary record of climatic changes in the northeastern Qinghai-Tibetan Plateau is not well obtained, because of high relief and extensive surface erosion. In this study, two long cores obtained from thick loess deposits in the region, both contain clear alternations of loess and paleosols, indicating distinct climate changes during the Quaternary. The palaeomagnetic stratigraphy and optically stimulated luminescence dating indicate that the loess deposition began approximately 2.0 Ma ago, with continuous accumulation until the Holocene. Dust accumulation rates in this region are much higher than those in the central Chinese Loess Plateau, suggesting an extended dust source and/or robust transport agent. Variations of magnetic susceptibility of the loess are a good proxy index of warm/wet and cold/dry alternations and are correlated with the intensity of pedogensis. The magnetic susceptibility record reveals that a relatively cold/dry climate dominated the northeastern Qinghai-Tibetan Plateau in the Quaternary, punctuated by warm/wet phases. A stepwise strengthening of the plateau summer monsoon, with a significant strengthening at around 1200-1000 ka and at least 7 phases of strengthening of the plateau summer monsoon in the past 800 ka are interpreted from the core data. The cores provide evidence that strengthened warm/wet climates occurred at around 80-130, 190-250, 290-340, 385-420, 500-625, 690-720 and 755-780 ka, which may correlate to warm/wet phases in the Qinghai-Tibetan Plateau. The palaeoclimate changes probably were regulated by the glacial-interglacial alternations.
By using aberration corrected scanning transmission electron microscopy we have found no small scale lateral In composition fluctuations exist in the In0.15Ga0.85N active region of a light emitting diode. Images were acquired at 2% of the electron dose known to create electron beam damage, so the acquired images reflect the intrinsic structure of the InGaN active region. Position averaged convergent beam electron diffraction reveals the local sample thickness where images were acquired is 4.8 nm, eliminating the possibility that the absence of composition variation was observed due to projection through a thick sample. In addition, 2-3 atomic layer steps were observed in the top surface of In0.08Ga0.92N layers and the In0.15Ga0.85N active layers, providing a possible mechanism for lateral carrier confinement.
Chemical wet etching on c-plane sapphire wafers by three etching solutions (H3PO4, H2SO4, and H3PO4/H2SO4 mixing solution) was studied. Among these etching agents, the mixing H3PO4/H2SO4 solution has the fastest etching rate (1.5 μm/min). Interestingly, we found that H2SO4 does not etch the c-plane sapphire wafer in thickness; instead, a facet pyramidal pattern is formed on the c-plane sapphire wafer. GaN light-emitting diode (LED) epitaxial structure was grown on the sapphire wafer with the pyramidal pattern and the standard flat sapphire wafer. X-ray diffraction and photoluminescence measurement show that the pyramidal pattern on the sapphire wafer improved crystalline quality but augmented the compressive stress level in the GaN LED epilayer. The horizontal LED chips fabricated on the pyramidal-patterned sapphire wafer have a larger light output than the horizontal LED chips fabricated on the standard flat sapphire wafer by 20%.
We report on a strong effect of p-GaN surface morphology on the growth mode and surface roughness of ZnO:Ga films grown by plasma-assisted molecular-beam epitaxy on p-GaN/c-sapphire templates. A range of ZnO:Ga surface morphologies varying from rough surfaces with well defined three-dimensional islands, capable to enhance light extraction in light-emitting diodes, to rather smooth surfaces with a surface roughness of ~ 2 nm suitable for vertical-cavity lasers can be achieved by controlling the surface morphologies of p-GaN. Optical transmittance measurements revealed high transparency exceeding 90% in the visible spectral range for ZnO:Ga with both types of surface morphology.
High-Electron Mobility Transistors (HEMTs) can be prepared by growing alternating epitaxial layers of InAlAs and InGaAs on InP substrates. Lattice matched HEMTs are obtained by growing layers of InxAl(1-x)As and InyGa(1-y)As with x ≃ 0.5227 and y ≃ 0.5324. Varying the values of x and y by controlling the individual flux during molecular-beam epitaxial (MBE) growth, one can obtain pseudomorphic HEMTs. Pseudomorphic HEMTs may have superior electronic transport properties and larger conduction band discontinuity when compared to an unstrained one. The precise control of the composition is thus important to the properties of HEMTs. This control is however very difficult and the values of x and y may vary from run to run.
We will demonstrate in this paper the capability of a double crystal rocking curve (DCRC) on the structure characterization. All the structure information: including composition and thickness of both the buffer and top InAlAs layers and the active channel InGaAs layer, can be obtained from one x-ray diffraction measurement. It is accomplished through a computer simulation process of DCRCs. The structure parameters of the epitaxial layers are used to calculate (simulate) the DCRCs. The simulated one is then to compare with the experimental curves. During the simulation one or more of these structure parameters are adjusted until the best fitted DCRC is obtained. The limitation of DCRC in measuring small variations in layer thickness as well as the small changes in composition for both InAlAs and InGaAs layers will be discussed.
When preparing single-crystal films of CaF2 on (111) oriented silicon by molecular beam epitaxy (MBE), we found that these dielectric films grew into either A or B type depending on the substrate temperature during growth. A-type films follow the same orientation as that of the substrate silicon, while B-type films rotate 180° about the surface normal with respect to the substrates.
X-ray diffraction (XRD) confirms the single crystallinity and identifies the epitaxial relationships between the film and the substrate. Epitaxial CaF2 films were obtained at growth temperatures ranging from 200°C to 800°C. Employing the asymmetric x-ray diffraction of atomic planes inclined to the sample surface, we found that A-type CaF2 grows at lower substrate temperatures, while B-type films dominate at higher temperatures.
Ion implantation was used to inject zinc ions into crystalline CaF2 and amorphous SiO2 substrates. Zn or ZnO nanoparticles were formed after annealing in a reducing (4% H2 + 96%Ar) or an oxidizing (10%O2 + 90% Ar ) atmosphere, respectively. When the sample was annealed in a reducing atmosphere, the absorption band at ∼ 5.3 eV for zinc implanted into SiO2 was attributed to zinc metal colloids. The absorption peak observed in the 4.3 – 4.7 eV region was due to the formation of ZnO nanocrystals, after the sample was annealed in an oxidizing environment. Both X-ray diffraction (XRD) and X-ray photospectroscopy (XPS) were used to confirm ZnO nanocrystal formation. For zinc implanted into CaF2, the as-formed ZnO nanocrystals were aligned with their  axes parallel to the  axis of the CaF2. Photoluminescence (PL) spectra showed UV and green emission from the zinc-implanted silica samples annealed under an oxygen atmosphere; however, no green emission was observed for ZnO formed in a CaF2 substrate. An additional emission was observed at ∼ 420 nm which might be due to F centers in CaF2 created by ion beam damage.
ZnO has recently attracted a great deal of attention as a material for transparent contacts in light emitters and adsorbers. ZnO films heavily doped with Ga (carrier concentration in the range of 1020 - 1021 cm-3) were grown on a-plane sapphire substrates by RF plasma-assisted molecular beam epitaxy. Oxygen pressure during growth (i.e. metal (Zn+Ga)–to–oxygen ratio) was found to have a crucial effect on structural, electrical, and optical properties of the ZnO:Ga films. As-grown layers prepared under metal-rich conditions exhibited resistivities below 3×10-4 Ω-cm and an optical transparency exceeding 90% in the visible spectral range. In contrast, the films grown under the oxygen-rich conditions required thermal activation and showed inferior structural, electrical, and optical characteristics even after annealing.
We report that bulk metallic glasses (BMGs) with large plasticity can be obtained in conventional brittle BMGs by a shrink-fit metal sleeve. The mechanical performance especially the plasticity in the Zr41.2Ti13.8Cu12.5Ni10Be22.5 BMG with a shrink-fit copper sleeve is much enhanced. The approach results in the formation of the highly dense and frequent interacting and arresting events of shear bands and is the origin of the observed large global plasticity. The results present another simple step toward toughening the inherently brittle BMGs.
Around the world, there are 20 types of wild and about 70 domestic quail breeds or strains, including laboratory and commercial quail. Although all domestic quails were derived from wild strains, many obvious differences are evident today. However, how these differences occurred and which wild population was the first to be domesticated, remains unclear. This paper systematically presents the history of the development of domestic quail in China from 770 B.C. to the end of the 20 century. Taking into account recent research on some structural loci of domestic and wild quail, and in the light of recent survey reports of the present general situation of these birds, particularly in respect of their ecological performance and differences between wild and domestic quail, this review puts forward a new thesis forresolving the current uncertainty about the origin of domestic quail. It is suggested that unlike those of Japanese origin, Chinese quail are probably the earlier and more direct ancestorof most kinds of the domestic quail found around the world. Moreover, the review analyzes the possible evolutionary path to domestic quail, which is mainly a result of the flow of people from Japan to China. On the assumption that more and more wild quail populations are endangered, it aims to provide a basis forrenewing knowledge of wild quail resources and supporting the protection and use of these valuable worldwide stocks. This is especially important in China, the last country in the world to have so many wild quail populations. Furthermore, this new insight can promote and assist the world commercial quail industry to develop and flourish.
In order to examine the chronologic changes in genetic variance and heritability of anthropometric characteristics of Chinese infants in Taiwan, a total of 521 pairs of same-sexed twin neonates given birth in four major general teaching hospitals in Taipei City were studied. Based on the placental pattern and 12 red blood cell antigens, 428 MZ and 93 DZ twin pairs were identified and followed up to the age of one year. There was no significant genetic variance for all anthropometric characteristics adjusted for sex and gestational week before the age of six months. After adjusting for sex and gestational week, a significant genetic variance was observed at the age of six months, with heritability values of 0.51 (weight), 0.63 (head circumference), 0.77 (chest circumference), and 0.53 (arm circumference), as well as at one year, although with considerably lower heritability values. This implies that growth is dynamically determined by both genetic and environmental factors during infancy.
In order to examine the genetic variance and heritability of temperament among Chinese infants in Taiwan, a total of 62 pairs of same-sexed twin infants given birth in four major general teaching hospitals in Taipei City were studied. Based on placentation and 12 red blood cell antigens, 44 MZ and 18 DZ pairs were identified. Temperament was assessed at the age of six months by the Chinese edition of Carey's Temperament scale. Significant genetic variance was observed for activity level, approach or withdrawal, intensity of reaction, quality of mood, and threshold of responsiveness, with a heritability of 0.64, 0.56, 0.74, 0.39, and 0.45, respectively. There was no significant intrapair difference in temperamental characteristics between monochorionic and dichorionic MZ twins.
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