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To explore the effect of yield stress on the secondary breakup of gel drops, experimental and theoretical investigations are carried out by employing a high-speed camera. A unique hemline-type breakup, as a modified behaviour of sheet-thinning breakup, occurs when the air velocity increases to a high region. The edges of the drops constantly deform into thin membranes when the high-velocity air skims over the gel drops. These membranes vibrate vertically, and breaking points occur at high amplitudes, causing the formation of reticular fragments. The results of linear stability analysis indicated that the yield stress of the gel drops has an influence on the formation and breakup of the gel membranes. The breakup regime map and breakup times are also studied.
Recently, the nature of viscoelastic drag-reducing turbulence (DRT), especially the maximum drag reduction (MDR) state, has become a focus of controversy. It has long been regarded as polymer-modulated inertial turbulence (IT), but is challenged by the newly proposed concept of elasto-inertial turbulence (EIT). This study is to repicture DRT in parallel plane channels by introducing dynamics of EIT through statistical, structural and budget analysis for a series of flow regimes from the onset of drag reduction to EIT. Some underlying mechanistic links between DRT and EIT are revealed. Energy conversion between velocity fluctuations and polymers as well as pressure redistribution effects are of particular concern, based on which a new energy self-sustaining process (SSP) of DRT is repictured. The numerical results indicate that at low Reynolds number ($Re$), weak IT flow is replaced by a laminar regime before the barrier of EIT dynamics is established with the increase of elasticity, whereas, at moderate $Re$, EIT-related SSP can get involved and survive from being relaminarized. This further explains the reason why relaminarization phenomenon is observed for low $Re$ while the flow directly enters MDR and EIT at moderate $Re$. Moreover, with the proposed energy picture, the newly discovered phenomenon that streamwise velocity fluctuations lag behind those in the wall-normal direction can be well explained. The repictured SSP certainly justifies the conjecture that IT nature is gradually replaced by that of EIT in DRT with the increase of elasticity.
The study of enclaves in granitic plutons provides fundamental information on the petrogenesis of their host rocks. Here we combine U–Pb zircon ages, petrography, geochemistry and Nd–Hf isotope composition to investigate the origin of dioritic–granodioritic enclaves and their host granodiorites and biotite granites in the Xuehuading–Panshanchong area, which is a pivotal site to study the Palaeozoic intracontinental orogenic processes of the South China Block. Obtained ages indicate that the host rocks were formed in early Silurian time (c. 432 Ma). The enclaves are fine grained, but with mineral assemblages similar to their hosts and contain amphibole, biotite and plagioclase. All rocks have fractionated rare earth element patterns ((La/Yb)N = 2.86–8.16), except for one biotite granite that has a concave rare earth element pattern ((La/Yb)N = 1.50). Most rocks are depleted in Ta–Nb–Ti, and have negative Eu anomalies and ϵNd(t) (–8.86 to –5.75) and zircon ϵHf(t) (–13.30 to –4.11, except for one, –39.08). We interpret that the enclaves were formed at the borders of magma-ascending conduits, where the mafic mineral crystallization was enhanced by rapid cooling. Conversely, the biotite granites were produced by fractional crystallization from a related granodiorite magma. The sample with a concave rare earth element pattern may have been influenced by hydrothermal fluid–melt interaction. Geochemical modelling suggests that the granodiorites were likely generated by disequilibrium melting of heterogeneous amphibolites in the middle–lower crust. Considering the geological data for the Palaeozoic magmatic rocks in the South China Block, we propose that the Xuehuading–Panshanchong magmatism was likely triggered by piecemeal removal of the thickened lithospheric root and subsequent thermal upwelling of mantle, without a mantle-derived magma contribution to the granites.
Exosomes derived from hepatocellular carcinoma (HCC) cells are nanovesicles and are involved in the occurrence and development of HCC, they also serve as important carriers and drug targets of nanodrug delivery systems. The external shape and internal structure of exosomes are important indexes of identification, and isolated intact morphology is crucial to biological function integrity. However, given their susceptibility to various influencing factors, the external shape and internal structure of exosomes derived from HCC cells remain incompletely studied. In this study, exosomes purified from HCC cells were isolated at different centrifugation speeds and examined via multiple electron microscopy (EM) techniques. The results demonstrate that exosomes possess a nearly spherical shape and bilipid membranous vesicle with a concave cavity structure containing electron-dense and coated vesicles, suggesting the possible existence of subpopulations of exosomes with specific functions. The exosomes isolated at ultracentrifugation (UC) speed (≥110,000×g) presented irregular and diverse external morphologies, indicating the effect on the integrity of the exosomes. Transforming growth factor signaling bioactive substances (TGF-β1, S100A8, and S100A9) can be found in exosomes by performing Western blotting, showing that the internal content is associated with metastasis of HCC. These findings show that EMelectron microscopy and UC speed can affect exosome characteristics, including external shape, internal structure, and content of bioactive substances. The electron-dense and coated vesicles that had been discovered in exosomes might become new additional morphological features, which could help to improve the interpretation of experimental results and widen our understanding of exosome morphology.
Maternal one-carbon metabolism during pregnancy is crucial for fetal development and programming by DNA methylation. However, evidence on one-carbon biomarkers other than folate is lacking. We, therefore, investigated whether maternal plasma methyl donors, that is, choline, betaine and methionine, are associated with birth outcomes. Blood samples were obtained from 115 women during gestation (median 26·3 weeks, 90 % range 22·7–33·0 weeks). Plasma choline, betaine, methionine and dimethylglycine were measured using HPLC-tandem MS. Multivariate linear and logistic regression models were used to estimate the association between plasma biomarkers and birth weight, birth length, the risk of small-for-gestational-age and large-for-gestational-age (LGA). Higher level of maternal betaine was associated with lower birth weight (–130·3 (95 % CI –244·8, –15·9) per 1 sd increment for log-transformed betaine). Higher maternal methionine was associated with lower risk of LGA, and adjusted OR, with 95 % CI for 1 sd increase in methionine concentration was 0·44 (95 % CI 0·21, 0·89). Stratified analyses according to infant sex or maternal plasma homocysteine status showed that reduction in birth weight in relation to maternal betaine was only limited to male infants or to who had higher maternal homocysteine status (≥5·1 µmol/l). Higher maternal betaine status was associated with reduced birth weight. Maternal methionine was inversely associated with LGA risk. These findings are needed to be replicated in future larger studies.
The on-site hydrogen supply is a key issue for the commercialization of the fuel cells, which is one of the important ways for realizing a hydrogen-economy society. Composite NaNH2–NaBH4 is regarded as a promising high-capacity hydrogen storage material. In this paper, the composite NaNH2–NaBH4 (2/1) was synthesized via a solid-state ball milling method. To improve the hydrogen generation kinetics, a multiplex metal boride Mg–Co–B was selected as the catalyst. It was found that Na3BN2 and metal Na were byproducts in the thermal decomposed sample by X-ray diffraction analysis. Thermogravimetry and differential thermal analysis indicated that the main decomposition stages of the catalyst promoted NaNH2–NaBH4 material were split into three stages. The activation energy of the Mg–Co–B promoted NaNH2–NaBH4 (2/1) material below 300 °C was 76.4 KJ/mol, which is only 47.9% of that of the pristine NaNH2–NaBH4 (2/1), and implying much better hydrogen generation kinetics.
Phase stability, elastic, and thermodynamic properties of (Co,Ni)3(Al,Mo,Nb) with the L12 structure have been investigated by first-principles calculations. Calculated phonon density of states show that (Co,Ni)3(Al,Mo,Nb) is dynamically stable, and calculated elastic constants indicate that (Co,Ni)3(Al,Mo,Nb) possesses intrinsic ductility. Young’s and shear moduli of the simulated polycrystalline (Co,Ni)3(Al,Mo,Nb) phase are calculated using the Voigt–Reuss–Hill approach and are found to be smaller than those of Co3(Al,W). Calculated electronic density of states depicts covalent-like bonding existing in (Co,Ni)3(Al,Mo,Nb). Temperature-dependent thermodynamic properties of (Co,Ni)3(Al,Mo,Nb) can be described satisfactorily using the Debye–Grüneisen approach, including heat capacity, entropy, enthalpy, and linear thermal expansion coefficient. Predicted heat capacity, entropy, and linear thermal expansion coefficient of (Co,Ni)3(Al,Mo,Nb) show significant change as a function of temperature. Furthermore the obtained data can be used in the modeling of thermodynamic and mechanical properties of Co-based alloys to enable the design of high temperature alloys.
We have demonstrated and studied polymeric solid-state dye lasers (SSDLs) fabricated by three-dimensional (3D) polystyrene colloidal crystals and tert-butyl roadamine B (t-Bu RhB) doped Poly (methyl methacrylate) (PMMA) films with different film thickness. The sandwich-typed resonator cavities with different active layer thickness display single-mode lasing oscillations in the reflection bandgap of the colloidal crystals. The lasing thresholds could be optimized by changing the thickness of t-Bu RhB doped PMMA films, which is as low as 7.43 W/cm2. Adjusting active layer thickness would provide an opportunity to accelerate the development of fabricating polymeric SSDLs with low threshold.
The development of near-isogenic lines (NILs) is an important fundamental step in the cloning of quantitative trait loci (QTL) and molecular marker assisted breeding. In the present study, NILs for two major QTLs of basal root thickness (BRT) and 1000-grain-weight (TGW) were obtained by molecular marker-assisted selection (MAS) through foreground selection for target QTL and background selection in three backcross generations (BC1F1, BC2F1 and BC3F1). After phenotypic evaluation in the BC3F2 generation, nine BRT QTL-NILs with BRT ranges of 1.07–1.16 mm (6.11–15.18% greater than the recurrent parent) and an average recovery ratio of genetic background (RRGB) of 97.22%, and 11 TGW QTL-NILs with ranges of 21.25–26.25 g (7.05–32.16% greater than the recurrent parent) and 95.97% of RRGB, were selected.
This trial was aimed at investigating the effect of different doses of progesterone (P4) and types of vaginal bolts on new follicular wave induction, oestrus synchronization and superovulation in Holstein heifers. Results showed that the interval after prostaglandin F2α (PGF2α) application and oestrus occurrence between the sponge blot (SP) group (48.3 h) and the progestin release device (PRD) group (39 h) was significantly different (P<0.05). The average number of embryos obtained in the SP group (13.2) was significantly higher than that (8.7) in the PRD group (P<0.05). The same trend was observed for the number of usable embryos (5.7 and 3.3 for SP and PRD groups, respectively). The injection of 50 and 100 mg of P4 efficiently induced a new follicular wave, whereas no significant difference (P>0.05) was recorded on oestrus synchronization and superovulation between the two groups.
A glacier system is regarded as the ensemble of many glaciers sharing the same region, influenced by a similar climate and organized by certain intrinsic laws. It can be either ‘sensitive’ or ‘steady’. On the basis of the structure of the glacier system and the nature of the equilibrium-line altitudes at the steady state, functional models of a glacier system responding to climate warming were established, using the Kotlyakov–Krenke equation relating annual glacier ablation and mean summer temperature and the glacier system’s median size. The modeling results under the climatic scenarios with a rate of temperature increase of 0.01, 0.03 and 0.05 K a-1 indicate that by the end of this century the glacial area of China will be reduced by –14%, –40%and –60% respectively. However, model results show distinct differences between the sensitive glacier system and the steady glacier system.
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