Search

The effect of curing temperature on hardening, thermal, and mechanical characteristics of adhesive for retard‐bonded prestressed systems is investigated in detail. To evaluate the degree of hardening of the adhesive, the cone penetration and Shore hardness of two samples are tested throughout the curing process under conditions of 25, 35, 45, 55, and 65°C. The thermal performance and curing reaction are characterized using differential scanning calorimetry and Fourier transform infrared spectroscopy, respectively. The mechanical properties with respect to the cure temperatures are characterized by compression strength tests. Experimental results present that after curing under conditions ranging from 25 to 65°C, the hardness of the samples reached its maximum values (85–90 D). As the temperature increased from 25 to 65°C, there was a greater degree of curing cross‐linking, resulting in an increase in compressive strength from 55 to 72 MPa. Based on Shore hardness–time experimental data, a logarithmic model is proposed for predicting the hardness of adhesives at any given time for engineering applications. Additionally, the time–temperature superposition principle is utilized to extrapolate the curing time of the adhesive under low‐temperature conditions. The research findings are of significant importance for the assessment of adhesive hardening. [ABSTRACT FROM AUTHOR]

Knowledge regarding the abundance and distribution of solar wind (SW)‐sourced water (OH/H2O) on the Moon in the shallow subsurface remains limited. Here, we report the NanoSIMS measurements of H abundances and D/H ratios on soil grains from three deepest sections of the Chang'E‐5 drill core sampled at depths of 0.45–0.8 m. High water contents of 0.13–1.3 wt.% are present on approximately half of the grain surfaces (topmost ∼100 nm), comparable to the values of Chang'E‐5 scooped soils. The extremely low δD values (as low as −995‰) and negative correlations between δD and water contents indicate that SW implantation is an important source of water beneath the lunar surface. The results are indicative of homogeneous distribution of SW‐derived water in the vertical direction, providing compelling evidence for the well‐mixed nature of the lunar regolith. Moreover, the findings demonstrate that the shallow subsurface regolith of the Moon contains a considerable amount of water. Plain Language Summary: Recently, China's Chang'E‐5 mission targeted a higher latitude on the Moon than previous Apollo and Luna missions, and brought back scooped and drilled samples to the Earth. These new soil samples provide an opportunity to investigate the distribution, abundance, and origin(s) of water in Moon's middle latitude. Here, we focus on using the NanoSIMS technique to analyze water content on soil near‐surface regions to understand whether the solar wind (SW)‐derived water could be preserved after burial at depth. Our results show that more than half of the core soils have high water contents on the rims of grains, similar to those of the Chang'E‐5 scooped soils. This finding suggests that the SW remains an important source of water in the Moon's subsurface. Our work provides direct evidence that the lunar regolith below the surface contains considerable water from SW implantation. This type of water could be a promising water resource in future exploration. Key Points: More than half of the soils from the single drill core have high water contents and low D/H ratios below the surfaceThe solar wind (SW)‐derived water could be preserved for hundreds of millions of years if buried at depthLunar regolith from the drill core contains considerable water from SW implantation, which is much more accessible [ABSTRACT FROM AUTHOR]

Uranium isotope ratios are reported for twenty‐nine geological reference materials (RMs) including igneous, metamorphic and sedimentary rocks, as well as sediments. Measurements were conducted on a multi‐collector inductively coupled plasma‐mass spectrometer (MC‐ICP‐MS) using the 233U‐236U double spike technique. These RMs possess a wide range of matrices with U mass fractions ranging from 0.11 μg g‐1 to 18.7 μg g‐1. The δ234/238U values (relative to the n(234U)/n(238U) ratio at secular equilibrium) show minor fluctuations around the secular equilibrium value except for two Pleistocene speleothem RMs. The δ238/235U values (relative to the value for NBL CRM 112a (NBS SRM 960)) of igneous rocks and metamorphic rocks are within the range of the continental crust value (‐0.29 ± 0.03‰, 95% CI). The δ238/235U value for sedimentary rock and sediment RMs spans a wide range of 0.98‰, suggesting significant 238U/235U isotopic fractionation in low temperature environments. The range of δ238/235U RMs reported in this study (‐0.63‰ to 0.35‰) exceeds that of previous RMs (‐0.61‰ to 0.17‰), allowing inter‐laboratory calibration of wider ranges of geological and environmental samples. [ABSTRACT FROM AUTHOR]

We present multitechnique U‐Pb geochronology and Hf isotopic data from zircon separated from rapakivi biotite granite within the Eocene Golden Horn batholith in Washington, USA. A weighted mean of twenty‐five Th‐corrected 206Pb/238U zircon dates produced at two independent laboratories using chemical abrasion‐isotope dilution‐thermal ionisation mass spectrometry (CA‐ID‐TIMS) is 48.106 ± 0.023 Ma (2s analytical including tracer uncertainties, MSWD = 1.53) and is our recommended date for GHR1 zircon. Microbeam 206Pb/238U dates from laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS) and secondary ion mass spectrometry (SIMS) laboratories are reproducible and in agreement with the CA‐ID‐TIMS date to within < 1.5%. Solution multi‐collector ICP‐MS (MC‐ICP‐MS) measurements of Hf isotopes from chemically purified aliquots of GHR1 yield a mean 176Hf/177Hf of 0.283050 ± 17 (2s, n = 10), corresponding to a εHf0 of +9.3. Hafnium isotopic measurements from two LA‐ICP‐MS laboratories are in agreement with the solution MC‐ICP‐MS value. The reproducibility of 206Pb/238U and 176Hf/177Hf ratios from GHR1 zircon across a variety of measurement techniques demonstrates their homogeneity in most grains. Additionally, the effectively limitless reserves of GHR1 material from an accessible exposure suggest that GHR1 can provide a useful reference material for U‐Pb geochronology of Cenozoic zircon and Hf isotopic measurements of zircon with radiogenic 176Hf/177Hf. Key Points: We suggest a new Eocene zircon reference material, GHR1.U‐Pb and Hf isotopic systematics in GHR1 zircon are homogeneous with a 206Pb/238U date of 48.106 +/‐ 0.023 Ma (2s) and a 176Hf/177Hf of 0.283050 +/‐ 17 (2s).GHR1 fulfills a need for abundant and easily available Cenozoic zircon reference materials. [ABSTRACT FROM AUTHOR]

The ambr bioreactors are single‐use microbioreactors for cell line development and process optimization. With operating conditions for large‐scale biopharmaceutical production properly scaled down, microbioreactors such as the ambr15™ can potentially be used to predict the effect of process changes such as modified media or different cell lines. While there have been some recent studies evaluating the ambr15™ technology as a scale‐down model for fed‐batch operations, little has been reported for semi‐continuous or continuous operation. Gassing rates and dilution rates in the ambr15™ were varied in this study to attempt to replicate performance of a perfusion process at the 5 L scale. At both scales, changes to metabolite production and consumption, and cell growth rate and therapeutic protein production were measured. Conditions were identified in the ambr15™ bioreactor that produced metabolic shifts and specific metabolic and protein production rates that are characteristic of the corresponding 5 L perfusion process. A dynamic flux balance (DFB) model was employed to understand and predict the metabolic changes observed. The DFB model predicted trends observed experimentally, including lower specific glucose consumption and a switch from lactate production to consumption when dissolved CO2 was maintained at higher levels in the broth. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 34:420–431, 2018 [ABSTRACT FROM AUTHOR]

We prepared thermally reduced graphene oxide (TRG) grafted with polymethyl methacrylate (PMMA) and polyvinyl acetate (PVAc) (TRG-g-PMMA and TRG-g-PVAc) by γ-ray irradiation-induced graft polymerization and studied their effects on poly( l-lactic acid) (PLLA) nanocomposites. PMMA and PVAc chains were proved to be grafted on the TRG surface successfully. TRG- g-PMMA and TRG- g-PVAc was found to restrict the crystallization behavior of PLLA compared with TRG. Moreover, tensile-test results showed that TRG- g-PMMA and TRG- g-PVAc could enhance the elongation at break of PLLA nanocomposites without reducing the tensile strength and modulus compared with TRG, which indicated that the grafting of PMMA and PVAc chains on TRG could improve the toughness of PLLA nanocomposites. POLYM. COMPOS., 38:5-12, 2017. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

Bulk major element composition, petrography, mineralogy, and oxygen isotope compositions of twenty Al-rich chondrules ( ARCs) from five CV3 chondrites (Northwest Africa [ NWA] 989, NWA 2086, NWA 2140, NWA 2697, NWA 3118) and the Ningqiang carbonaceous chondrite were studied and compared with those of ferromagnesian chondrules and refractory inclusions. Most ARCs are marginally Al-richer than ferromagnesian chondrules with bulk Al2O3 of 10-15 wt%. ARCs are texturally similar to ferromagnesian chondrules, composed primarily of olivine, pyroxene, plagioclase, spinel, Al-rich glass, and metallic phases. Minerals in ARCs have intermediate compositions. Low-Ca pyroxene (Fs0.6-8.8Wo0.7-9.3) has much higher Al2O3 and TiO2 contents (up to 12.5 and 2.3 wt%, respectively) than that in ferromagnesian chondrules. High-Ca pyroxene (Fs0.3-2.0Wo33-54) contains less Al2O3 and TiO2 than that in Ca,Al-rich inclusions ( CAIs). Plagioclase (An77-99Ab1-23) is much more sodic than that in CAIs. Spinel is enriched in moderately volatile element Cr (up to 6.7 wt%) compared to that in CAIs. Al-rich enstatite coexists with anorthite and spinel in a glass-free chondrule, implying that the formation of Al-enstatite was not due to kinetic reasons but is likely due to the high Al2O3/CaO ratio (7.4) of the bulk chondrule. Three ARCs contain relict CAIs. Oxygen isotope compositions of ARCs are also intermediate between those of ferromagnesian chondrules and CAIs. They vary from −39.4‰ to 13.9‰ in δ18O and yield a best fit line (slope = 0.88) close to the carbonaceous chondrite anhydrous mineral ( CCAM) line. Chondrules with 5-10 wt% bulk Al2O3 have a slightly more narrow range in δ18O (−32.5 to 5.9‰) along the CCAM line. Except for the ARCs with relict phases, however, most ARCs have oxygen isotope compositions (>−20‰ in δ18O) similar to those of typical ferromagnesian chondrules. ARCs are genetically related to both ferromagnesian chondrules and CAIs, but the relationship between ARCs and ferromagnesian chondrules is closer. Most ARCs were formed during flash heating and rapid cooling processes like normal chondrules, only from chemically evolved precursors. ARCs extremely enriched in Al and those with relict phases could have had a hybrid origin (Krot et al. 2002) which incorporated refractory inclusions as part of the precursors in addition to ferromagnesian materials. The occurrence of melilite in ARCs indicates that melilite-rich CAIs might be present in the precursor materials of ARCs. The absence of melilite in most ARCs is possibly due to high-temperature interactions between a chondrule melt and the solar nebula. [ABSTRACT FROM AUTHOR]

Highlights: [•] Expression of miR-625 in EC specimens was significantly lower than in corresponding adjacent tissues. [•] Low expression of miR-625 positively correlated with the proliferation and invasion of EC cell lines in vitro. [•] Direct binding of miR-625 to the Sox2 3′ UTR was demonstrated. [•] miR-625 overexpression diminished but miR-625 knockdown increased Sox2 expression levels in EC cells. [•] miR-625 is related to proliferation and invasion of EC by regulating Sox2. [Copyright &y& Elsevier]

Polysulfone (PSF) microspheres with a hollow core/porous shell structure were prepared by a water-in-oil-in-water emulsion solvent evaporation method. The morphology of PSF could be controlled by variation of the surfactants, which included oleic acid, poly(vinyl pyrrolidone), and tween 80. The three kinds of prepared microspheres were developed as sorbents for the selective removal of oil from water. PSF microspheres with a hollow core/porous shell structure exhibited the best separation efficiency, which was 44.8 times higher than that of the pristine PSF powder. The oil-absorbed microspheres combined with unsinkability, appropriate size, and highly hydrophobic and superoleophilic properties could be quickly distributed and collected in seconds and exhibited recyclability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 [ABSTRACT FROM AUTHOR]

The Baizhangyan skarn-porphyry type W- Mo deposit is located in a newly defined Mo- W- Pb- Zn metallogenic belt, which is in the south of Middle- Lower Yangtze Valley Cu- Fe- Au polymetallic metallogenic belt in SE China. The W- Mo orebodies occur mainly within the contact zone between fine-grained granite and Sinian limestone strata. There are two types of W- Mo mineralization: major skarn W- Mo mineralization and minor granite-hosted disseminated Mo mineralization which was traced by drilling at depth. Eight molybdenite samples from Mo-bearing ores yield Re- Os dates that overlap within analytical error, with a weighted average age of 134.1 ± 2.2 Ma. These dates are in close agreement with SIMS U- Pb concordant zircon age for fine-grained granite at 133.3 ± 1.3 Ma, indicating that crystallization of the granite and hydrothermal molybdenite formation were coeval and likely cogenetic. The Baizhangyan W- Mo deposit formed in the Early Cretaceous extensional tectonic setting at the Middle- Lower Yangtze Valley metallogenic belt and the Jaingnan Ancient Continent. Based on mineral compositions and crosscutting relationships of veinlets, hydrothermal alteration and mineralization, the ore mineral paragenesis of the Baizhangyan deposit is divided into four stages: skarn stage ( I), oxide stage ( II), sulfide stage ( III), and carbonate stage ( IV). Fluid inclusions in garnet, scheelite, quartz and calcite from W- Mo ores are mainly aqueous-rich ( L + V) type inclusions. Following garnet deposition at stage I, the high-temperature fluids gave way to progressively cooler, more dilute fluids associated with tungsten-molybdenite-base metal sulfide deposition (stage II and stage III) (162-360°C, 2.7-13.2 wt % NaCl equivalent) and carbonate deposition (stage IV) (137-190°C, 0.9-5 wt % NaCl equiv.). Hydrogen-oxygen isotope data from minerals of different stages suggest that the ore-forming fluids consisted of magmatic water, mixed in various proportions with meteoric water. From stage I to stage IV, there is a systematic decrease in the homogenization temperature of the fluid-inclusion fluids and calculated δ18O values of the fluids. These suggest that increasing involvement of formation water or meteoric water during the fluid ascent resulted in successive deposition of scheelite and molybdenite at Baizhangyan. [ABSTRACT FROM AUTHOR]

The article discusses uranium-thorium-lead dating of accessary minerals for Kimberlite and Lamproite. It mentions that Kimberlite and lamproite are potassic ultramafic rocks originating from the deep lithospheric mantle. It mentions that the rocks are necessary for finding the composition and structure of the lithosphere.

The article discusses evidences for late paleozoic and mesozoic basaltic magmatism in Southwestern Cameroon. It mentions impacts for correlations between the Gulf of Guinea in Africa and Northeast Brazil. It mentions that basalt dikes are olivine-containing tholeiites, less enriched in trace and rare earth elements.