Search

This study aimed to evaluate the effects of in-utero exposure to HIV and ART on pregnancy outcome and early growth of children. This cohort study enrolled 802 HIV-infected pregnant women between October 2009 and May 2018 in Guangzhou, China. The women were assigned to receive combination ART (cART) or mono/dual ART or no treatment. The primary outcomes were the combined endpoints of any adverse pregnancy outcome [including ectopic pregnancy, spontaneous abortion, stillbirth, preterm birth, small for gestational age (SGA)] and adverse early growth outcome (including infant death, HIV infection of mother-to-child transmission, and underweight, wasting and stunting of infants at 4 weeks of age). Adverse pregnancy outcomes occurred in 202 (35.1%) of all enrolled HIV-infected women, and 121 (31.3%) of all infants exhibited adverse effects on early growth at 4 weeks of age. The rates of adverse pregnancy outcomes, spontaneous abortion, ectopic pregnancy, stillbirth, infant death and perinatal HIV infection were higher among women not receiving ART, compared to those treated with cART or mono/dual ART (P < 0.05). However, women treated with cART had a higher rate of SGA, compared to untreated women (P < 0.05). No differences in early infant growth were observed among the different treatment regimens. Our findings underscore the essentiality of prioritizing HIV-positive pregnant women for ART, as even mono/dual ART available in resource-limited countries could improve pregnancy outcomes and infant survival. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Amphibole-rich clots are vestiges of residual pyroxene-rich precursors from the source after partial melting. • The microgranular enclaves of the Tongshanling granodiorite are reworked restite enclaves. • A model illustrating the formation process of reworked restite enclave has been proposed. • The fertile amphibolitic source is beneficial to the formation of Cu-Pb-Zn-bearing granodiorites in the Nanling Range. Abstract Microgranular enclaves, which can provide important petrogenetic indications for the host granitoids, are commonly observed in the Middle-Late Jurassic Cu-Pb-Zn-bearing granodiorites in the Nanling Range of South China. The origin of these Cu-Pb-Zn-bearing granodiorites is still controversial, with two different hypotheses: crust-mantle mixing and partial melting of the mafic lower crust, primarily based on geochemistry and geochronology. Detailed petrographic and mineralogical studies have been carried out on the Tongshanling granodiorite and its microgranular enclaves to provide new textural and compositional constraints on the petrogenesis. The microgranular enclaves have dioritic compositions with a mineralogy dominated by plagioclase, amphibole, and biotite. Abundant residual materials, such as mafic mineral clots, inherited and metamorphic zircon, and Ca-rich core plagioclase, occur in the enclaves and are in favor of a restite origin. The amphibole-rich clots are considered as vestiges of residual pyroxene-rich precursors from the source. Three different types of amphibole, i.e., magmatic, metamorphic, and magma reworked metamorphic amphibole, have been recognized in the granodiorite and its enclaves. The magmatic amphibole occurs as enclosed and idiomorphic isolated crystals in the granodiorite with Al and Si contents of 1.34–2.12 apfu (atoms per formula unit) and 6.25–6.88 apfu, respectively, and a ΣREE content of 307–764 ppm. The metamorphic amphibole, with a granoblastic triple-junction texture, occurs as aggregated crystals dominantly in the enclaves and a few in the granodiorite. It has actinolitic compositions (Al: 0.31–0.81 apfu, Si: 7.33–7.72 apfu) and distinctly lower contents of incompatible elements (ΣREE: 99–146 ppm). The magma reworked amphibole has intermediate compositions (Al: 0.81–1.59 apfu, Si: 6.71–7.35 apfu, ΣREE: 317–549 ppm) between the magmatic and metamorphic amphibole. The zonal amphibole-rich clots exhibit increasing Al and decreasing Si contents from interior amphibole to exterior amphibole and also from core to rim in amphibole grains, and the outer parts of enclave magmatic zircon have higher ThO 2 + UO 2 contents and lower Zr/Hf ratios than the inner parts, showing the process of magma reworking of the restite enclaves. Based on the textural and compositional evidence, these microgranular enclaves are thought to be reworked restite enclaves. This is also supported by thermobarometric calculation. A model illustrating the formation process of reworked restite enclave has been proposed. Combined with previous experimental studies of partial melting, the Tongshanling granodiorite is deduced to be derived from dehydration melting of amphibolite in the mafic lower crust. The fertile amphibolitic source is beneficial to the formation of Cu-Pb-Zn-bearing granodiorites in the Nanling Range. [ABSTRACT FROM AUTHOR]

Chloride is the most important anion in ore-forming hydrothermal fluids, and chlorine isotopes are therefore potentially sensitive tracers of the origin and evolution of ore-forming fluids. However, they remain a relatively under-utilized tool in ore deposit geochemistry due to the lack of knowledge of chlorine isotope fractionation during ore-forming processes. Using first-principles density functional theory, this study estimates chlorine isotope fractionation factors for various ore-forming processes. All metal-Cl complexes in hydrothermal fluids are enriched in 37Cl compared to chloride ions, but the change in δ37Cl of the fluid trapped in ore minerals is small after the destabilization of metal-chloride complexes during ore mineral deposition. In the precipitation of evaporite minerals from brine, the sequence of enrichment of the heavy Cl isotope (37Cl) is halite > carnallite > aqueous chloride > kainite > sylvite > bischofite. The results of this study agree with the experimental observations that progressive precipitation of halite from brine lowers the δ37Cl value of the residual fluid until the formation of K-Mg chlorides. In low-temperature deposits, δ37Cl values for fluid inclusions and minerals reflect those of the hydrothermal fluid provenance and the mixing of this fluids with saltwater or basinal brines. In high-temperature magmatic-hydrothermal ore deposits that undergo liquid–vapour phase separation, chlorine isotopes fractionate among phases of silicate melt, vapour and chloride-rich liquid. The considerable range in δ37Cl in fluid inclusions may also reflect fluid mixing and hydrothermal alteration. At ambient temperature, the δ37Cl values may reflect evaporative processes and, in the case of chemical weathering of metallic mineral deposits, may record the supergene enrichment of the metals. This study highlights the use of chlorine isotopes as a new tool for interpreting ore-forming processes. [ABSTRACT FROM AUTHOR]

The Nanling Range in South China hosts numerous W–Sn–rare metal deposits associated with several cycles of polygenetic granitic intrusions. In the Wangxianling area of the middle Nanling Range, igneous intrusions include the Wangxianling and Hehuaping granite plutons and more than 20 granite porphyry dykes. The Wangxianling pluton has a central phase of medium-grained tourmaline two-mica granite and a marginal phase of medium-grained tourmaline muscovite granite. The pluton hosts several tungsten deposits including Shuiyuanshan and Yejiwo. Mineralization type is dominantly scheelite greisen, with subordinate scheelite skarn and wolframite–quartz veins. The Hehuaping pluton composed of coarse-grained biotite granite and granite porphyry dykes to the east of the Wangxianling pluton have an associated Hehuaping tin deposit with tin skarn and subordinate porphyry and greisen mineralization. In situ zircon and cassiterite U–Pb dating, molybdenite Re–Os and muscovite 40 Ar– 39 Ar dating techniques are used to refine the age spectra of granitic rocks and W–Sn mineralization in the Wangxianling area. Granites of the Wangxianling pluton have zircon U–Pb ages of ~ 224 Ma. Tungsten-bearing quartz veins from both the Shuiyuanshan and Yejiwo tungsten deposits have an average molybdenite Re–Os isochron age of ~ 224 Ma, and muscovite of scheelite greisen from the Shuiyuanshan tungsten deposit yields a 40 Ar– 39 Ar plateau age of 214 Ma. The two mineralization ages are consistent with the zircon U-Pb age of the Wangxianling pluton indicating a close association between pluton emplacement and W mineralization in the Late Triassic. Both the Hehuaping pluton and granite porphyry dykes have zircon U–Pb ages of ~ 156 Ma. In situ LA–ICP–MS U–Pb dating of cassiterite in both the tin skarn and tin greisen yields an average age of ~ 156 Ma, showing that the Sn mineralization occurred at a similar time to the Late Jurassic granitic magmatism. Thus, two mineralization events are identified in the Wangxianling area, and include an earlier W dominant mineralization event and a later Sn dominant mineralization event. The earlier event is related both spatially and temporally to intrusion of the Late Triassic S-type Wangxianling granite pluton, whereas the later mineralization is associated both spatially and temporally with intrusion of the Late Jurassic Hehuaping A 2 -type granite pluton and A 2 -type granite porphyry dykes. [ABSTRACT FROM AUTHOR]

Abstract: The Shi-Hang zone is an important NE trending Mesozoic magmatic belt composed of granites with relative high εNd(t) values and young TDM model ages in South China. However, the petrogenesis and the tectonic environment for the Shi-Hang zone magmatic rocks remain controversial. We report here mineral chemistry, geochemical and Sr–Nd–Hf isotopic data for the Cailing and Furong granites and mafic microgranular enclaves (MMEs) from the Qitianling granite batholith in southern Hunan province, South China. The Qitianling granite batholith is a multi-staged composite pluton with three phases (Cailing, Furong, and Huangtangling) according to their ages and petrography. The Cailing (163–160Ma) and Furong (157–153Ma) phases are mainly composed of porphyritic amphibole–biotite monzogranite, and they share similar geochemical and isotopic characteristics. Both of them show similar SiO2 contents from 66.50 to 70.28%, and metaluminous A/CNK values of 0.80 to 0.98. The granites are characterized by high contents of large ion lithosphile elements (LILE) such as Rb, Th, U, Pb; high field strength elements (HFSE) such as Nb, Ta, Zr, Hf; and Zr+Nb+Ce+Y contents >350ppm, and high 10,000∗Ga/Al ratios >2.6. Chondrite-normalized REE patterns show relative enrichment of light rare earth elements (LREEs) and significant negative Eu anomalies. Mineralogical and geochemical features suggest that the Cailing and Furong granites are A-type, which can be further classified as A2 subtype. They have relatively lower (87Sr/86Sr)i ratios (0.7091–0.7132), higher εNd(t) values (−5.5 to −7.6) and younger Nd isotopic model ages (1.48–1.56Ga) than those common S-type granites in South China. Zircon εHf(t) values vary from −8.1 to −3.7. The MMEs in the Cailing phase show similar trace element and Sr–Nd isotopic characteristics with the host granites. But zircons from the MMEs show different εHf(t) values (−6.4–+2.6) with those from the host granites (−8.1 to −3.7). This indicates that the MMEs and host granites were crystallized from different sources of magmas, providing direct evidence for mafic–felsic magma mixing processes. The isotope data indicate that the Cailing and Furong granites from the Qitianling batholith were derived from a hybrid magma consisting of about 80% felsic magma derived from old crust and about 20% mantle-derived mafic magma. The strong magma mixing at about 160–155Ma caused by intra-arc rifting or back arc extension related to subduction of the Paleo-Pacific plate, is favored to explain the petrogenesis of the Cailing and Furong granites, as well as the Shi-Hang zone. [Copyright &y& Elsevier]

Abstract: Alzheimer''s disease (AD), the most common form of dementia, is characterized by the deposition of amyloid plaques, accumulation of fibrillary tangles in neurons, neurite degeneration, loss of neurons, and a progressive loss of cognitive function. The pathogenesis of AD is not fully understood, and no strong disease-modifying therapies are currently available. Recent studies suggest that the pan-neurotrophin receptor, p75NTR, is a critical factor involved in the pathogenesis of AD. In this review, we have discussed the roles of p75NTR in the production of amyloid-beta (Aβ), neuronal death, neurite degeneration, tau hyperphosphorylation, cell cycle re-entry and cognition decline in AD, and proposed that p75NTR is a potential target for the development of therapeutic drugs for AD. Finally we provide perspectives in developing various therapeutic strategies targeting different aspects of AD hallmarks which relate to p75NTR functions and breaking the p75NTR-mediated positive feedback loop which promotes the cascades in the pathogenesis of AD. [Copyright &y& Elsevier]

The geochemistry of Ba is commonly used to study igneous processes and fluid-melt interaction in subduction zone and granitic environments. Recent advances in analytical techniques have also indicated that Ba isotope geochemistry has the potential to significantly augment these studies. Understanding the Ba isotope fractionation mechanisms is thus critical if this potential is to be fully realized. Hence, we have used the first-principles calculations based on the density functional theory (DFT) and long-time ab initio molecular dynamics (AIMD) simulation to calculate Ba isotope fractionation during felsic magma evolution. In fluids, the reduced partition function ratio (β factor) of aqueous Ba2+ is highly variable, depending on the coordination number (n) of H 2 O in the first hydration shell. At ambient surface conditions on the Earth, n = 8 best represents the aqueous Ba2+ species in natural fluid, and the temperature-dependent equilibrium Ba isotope fractionation between barite/witherite and fluids can be described by the relationships: 103ln α witherite-fluid = −0.00009×(106/T2) 2 + 0.0603×(106/T2) + 0.0003 and 103ln α barite-fluid = −0.0001×(106/T2) 2 + 0.0648×(106/T2) + 0.0004, which is consistent with previous theoretical and experimental studies. In hydrothermal fluids, the hydration number of Ba2+ varies from 4 to 6 at high P-T, and the cumulative average of 103lnβ is derived to be 0.0798 ± 0.005‰ in 923.15 K and 0.2 GPa. In silicate minerals, the enrichment of heavy Ba isotopes decreases in the sequence of muscovite > microcline ≈ celsian ≈ sanbornite > barylite > phlogopite. Variations in Ba concentrations and the degree of Al-Si disordering only induce limited Ba isotope fractionation, which would be hard to distinguish analytically. At high temperatures (> 600 °C), the melt phase is enriched in heavy Ba isotopes relative to any coexisting aqueous fluid and crystallizing minerals. During the early stages of felsic magma differentiation involving plagioclase crystallization as the main mineral, the δ138/134Ba and concentration in the residual melt remain close to their initial values, but any fluid exsolved from the melt will have light δ138/134Ba values. The high Ba distribution coefficient of K-feldspar means that the resultant K-feldspar granite inherits > 90% of the Ba contained in the initial magma reservoir. Hence, the δ138/134Ba of K-feldspar is close to that of the initial melt. During the final stage of felsic magma evolution, mixing of exsolved fluids from deeper reservoirs may significantly reduce the δ138/134Ba of the now Ba-depleted melt, and can account for the low δ138/134Ba values measured in highly differentiated leucogranites and pegmatites. [ABSTRACT FROM AUTHOR]

Abstract: The coefficient of thermal expansion (CTE) is one of the critical design parameters for the application of materials in cryogenic engineering and study of available results demonstrates that thin films have different properties from their bulk counterparts. However, few universal techniques have been developed to measure the CTE of thin films at cryogenic temperatures. Furthermore, the possible effect of the applied stress levels on CTE testing results has not received enough attention. In this study, two novel testing methods, one direct and the other indirect, for determining the CTE of thin films under different applied stress levels at cryogenic temperatures are proposed. The test temperature is from room temperature to 77K and a lower temperature could be reached. Advantages of the two methods are also discussed. [Copyright &y& Elsevier]

In this paper, the fishlike phase diagrams for the quaternary system of alkyl polyglucoside (APG: C8/10Gj or C12/14Gj)/alcohol/alkane/water mixtures have been studied. By using the simple mass balance equation and the HLB plane equation, some important parameters were calculated, such as the coordinates of the start point B and the end point E of the three-phase region, the mass fraction of alcohol in the hydrophile–lipophile balanced interfacial layer, AS, and the mass fractions of APG and alcohol in the interfacial layer (CS and CA). The effects of different alcohols and oils on the phase diagram and on the composition of the interfacial layer were also investigated. The shorter the carbon chain length of the oils and the longer the carbon chain length of the alcohols used in the systems, the higher the solubilization of the microemulsions. [Copyright &y& Elsevier]