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Combination of Silica Sol and Potassium Silicate via Isothermal Heat Conduction Microcalorimetry

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Chinese Journal of Chemistry 2011年第2期29卷 356-362页

作者： tian Hebao Zhang Chaocan Liu Peng Li Xi Wu Lili Chen Yanjun School of Materials Science and Engineering Wuhan University of Technology Wuhan Hubei 430070 China Department of Chemistry School of Sciences Wuhan University of Technology Wuhan Hubei 430070 China

Isothermal heat conduction microcalorimetry was utilized as a novel characterization method to investigate the polymerization processes of silica with both thermodynamic and kinetic parameters when the combination of silica sol and potassium silicate was stirred at temperatures of 25.0, 35.0, and 45.0 ℃. The silica polymerization was characterized by the greater enthalpy change at each higher temperature and by the reaction orders of the silica sol and potassium silicate, which varied rapidly, instantaneously, and constantly from low to high all the time, up and down in an alternate manner. When the reaction order of the silica sol and potassium silicate was 3.0, the maximum rate constant occurred at 25.0℃ （k= 1.22 × 10 ^-4 mol-2·dm6·s-1）. The two temperature regions （25.0-35.0 ℃ region with a faster rate and 35.0-45.0℃ region with a lower rate） reflected a two-stage oligomerization of silica monomers with different oligomers formed in a two-step anionic mechanism. The measurements of particle size and pH value showed that the colloidal particles in the mixed silica sol and potassium silicate first dissolved, then ＂active＂ silica in the potassium silicate redeposited to make a distinct particle size distribution （Z-average size, 33.0-14.9 nm at 25.0 ℃） influenced both by pH value （9.82--11.97 at 25.0 ℃） and the mass fraction （53, 65, 75, and 85 mass/%） of the silica sol in the mixture. The processes of combination of the silica sol and potassium silicate did not result from acid-base neutralization reactions but from a complex polymerization of the ＂active＂ silica components which relate to silica monomers oligomerization with heat evolved （the total enthalpy changes, 1.6234-3.3882 J）.

关键词： silica sol silicates nanoparticles microcalorimetry thermodynamics kinetics

An experimental study on fine structures of supersonic laminar/turbulent flow over a backward-facing step based on NPLS

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Chinese Science Bulletin 2012年第6期57卷 584-590页

作者： CHEN Zhi YI ShiHe HE Lin tian LiFeng ZHU YangZhu College of Aerospace and Material Engineering National University of DeJense TechnologyChangsha 410073China

Fine structures of supersonic flow over a 5 mm high backward facing step(BFS),including expansion wave fan,reattachment shock,supersonic boundary layer were measured in a Ma=3.0 low-noise indraft wind *** varying the superficial roughness of the wall upstream from the step,supersonic laminar flow and supersonic turbulent flow could be formed over a *** on the spatiotemporal features of the holistic flow field and the fine structures in four typical regions were carried out using NPLS(nano-based planar laser scattering).Flow structures,including expansion wave fan,reattachment shock,supersonic boundary layer and its separation,reattachment and redevelopment are revealed by measuring the holistic structure of the transient flow *** the two time-averaged flow fields with each other,it is apparent that supersonic turbulent flow over a BFS(STF-BFS) has a larger expansion angle and a shorter recirculation region,and its redeveloped boundary layer increases at a smaller obliquity while the angle of reattachment shock is the same for the supersonic laminar flow over a BFS(SLF-BFS).With regard to time-evolution features,the K-H vortices in the SLF-BFS suffers from shearing,expansion,reattachment and three-dimensional effects while in the STF-BFS large-scale structures are affected by the incline and distortion at the reattachment point due to expansion,viscosity and *** on local regions indicate that in the SLF-BFS,the emergence of compression waves which distinctly converge into a reattachment shock is due to the local convective Mach number and the inducement of K-H vortices in the free shear ***,in the STF-BFS,compression waves and K-H vortices are barely evident,and the formation of a reattachment shock is related to the wall compressive effect.

关键词：超音速流不良贷款结构实验湍流层流后台阶超音速边界层黑脸琵鹭

Reversible congestive heart failure associated with hypocalcemia:A case report

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World Journal of Clinical Cases 2021年第34期9卷 10659-10665页

作者： Chu Wang Li-Wen Dou tian-Bing Wang Yang Guo Trauma Rescue&Treatment Center Peking University People's HospitalBeijing 100044China Emergency Department Peking University People's HospitalBeijing 100044China

BACKGROUND Hypoparathyroidism is a rare disease that may occur due to primary or secondary *** estimated incidence in the United States is 24–37/100000 *** heart failure associated with hypocalcemia due to hypoparathyroidism is an even rarer *** SUMMARY Here,we present a 64-year-old woman with congestive heart failure following *** patient was transferred to our emergency department with complaints of rapidly progressive dyspnea,shortness of breath and heaviness of the chest for 4 *** had a history of undergoing thyroidectomy and partial tracheotomy 2 years prior due to a malignant thyroid *** spasms had been present 1 year ago,and cataracts were treated with intraocular lens replacement in both *** tests were within normal ranges,except serum calcium at 1.33 mmol/L(2.20–2.65 mmol/L),ionized calcium at 0.69 mmol/L(1.15–1.29 mmol/L),and parathyroid hormone at<1.0 pg/mL(12–88 pg/mL).Echocardiography revealed an ejection fraction of 28.48%.Cardiac function was quickly reversed by restoring the serum calcium *** improvements were noted with an ejection fraction of up to 48.50%at *** For patients with potential hypocalcemia,monitoring calcium levels and dealing with hypocalcemia in time to avoid serious complications are important.

关键词： Hypoparathyroidism Congestive heart failure Cardiomyopathy Parathyroid hormone Calcium Echocardiography Case report

Optical Nonlinearity of Subwavelength Metal-dielectric Gratings: Effects of Strong Anisotropy

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Chinese Physics Letters 2011年第9期28卷 143-146页

作者： KANG Xiu-Bao tian Tai-He WANG Zhi-Guo Department of Physics Tongji UniversityShanghai 200092 Henan Polytechnical School of Science and Engineering Zhengzhou 450008

The optical nonlinear properties of an effective anisotropic slab made of metal-dielectric lamellar gratings with a small grating-period-to-wavelength ratioΛ/λ→0 is *** is shown that when a transverse magnetic electromagnetic wave obliquely illuminates such a slab,whose effective normal permittivity is much smaller than its tangential one,the normal wave vector inside the effective medium is extremely sensitive to the fluctuation of the tangential effective *** on this characteristic,obvious nonlinear modifications of the phase delay and step−like transmission are obtained by a moderate input intensity even if the thickness of the slab structure is only less thanλ/6.

关键词： dielectric Strong delay

Effect of low-temperature ausforming on bainitic transformation and mechanical properties in ultrahigh-strength bainitic steel

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Journal of Iron and Steel Research International 2023年第9期30卷 1843-1853页

作者： tian-yu Zhang Ling-yu Wang Yu Wang Jun Hu Hong-shuang Di Wei Xu State Key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819LiaoningChina

Low-temperature ausforming(LT-AF)prior to bainitic transformation leads to a noticeable acceleration of bainitic transformation kinetics;however,the effect of LT-AF on the retained austenite(RA)features and the resulting mechanical properties is still ***-AF was applied to ultrahigh-strength bainitic steel before *** deformation behavior and the resulting dislocation substructures were investigated by thermomechanical simulator and transmission electron microscopy(TEM).The planar dislocation structures produced during deformation at 350℃ accelerate the bainitic transformation kinetics during isothermal *** effect of LT-AF on the bainitic transformation kinetics and the features of RA was elucidated via dilatometer measurement,TEM,scanning electron microscopy,and X-ray *** is observed that LT-AF not only retains more RA content but also facilitates improved RA *** trend is mainly due to the large amounts of planar dislocations in RA and bainitic laths inherited from undercooled austenite caused by LT-AF,the decrease in bainitic sheaves size,and the increase in filmy RA content compared to the sample without ausforming.A large fraction of filmy RA with high stability and the refinement of bainitic sheaves obtained by LT-AF remarkably enhance the strain hardening capacity and achieve significantly better ductility compared to the directly austempered sample.

关键词： Ultrahigh-strength bainitic steel Bainitic transformation Low-temperature ausforming Retained austenite Strain hardening rate

Oxygen and carbon isotope records of calcareous nanno-fossils for the past 1 Ma in the southern South China Sea

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Chinese Science Bulletin 2002年第10期47卷 798-803页

作者： LIU Chuanlian CHENG Xinrong ZHU Youhua tian Jun XIA Peifen Key Laboratory of Marine Geology of Ministry of Education Tongji UniversityShanghai 200092China Nanjing Institute of Geology and Palaeontology Chinese Academy of SciencesNanjing 210008China

Oxygen and carbon isotopic analyses have been carried out on calcareous nannofossils from ODP Site 1143 in the southern South China Sea. The results demonstrate that the δ18O values of calcareous nannofossils for the past 1 Ma vary systematically with those of planktonic and benthic foraminifera from the same site. But the average δ18O value of nannofossils is 1.869‰ higher than that of planktonic foraminifera, and is 3.855‰ lower than that of benthic foar-minifera. There are systematic differences between the δ13C values of nannofossils, planktonic foarminifera and benthic foraminifera. The average δ13C of nannofossils is 0.756‰ higher than that of benthic foraminifera, and is 0.460‰ lower than that of planktonic foraminifera. The δ13C values of nannofossils exhibit a significant positive shift beginning near isotope stage 14 and lasting until stage 8. This study also finds that there is a close ralationship between the δ13C of nannofossils and the percentage of Florisphaera profundo. This

关键词： oxygen and carbon isotope calcareous nannofossil South China Sea.

Functional properties of defatted chickpea flour heat-induced gels

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International Journal of Agricultural and Biological Engineering 2024年第2期17卷 280-286页

作者： Chonghao Bi Aoxue Qie Tong Zhou Yi Liu Bin tian School of Artificial Intelligence Beijing Technology and Business UniversityBeijing 100048China

Defatted chickpea flour(DCF),which is a by-product of chickpea oil extraction industry,is rich in nutrients that are beneficial to human *** this study,the effects of temperature and DCF variation on the rheological properties,water holding capacity,freeze-thaw stability and microstructure of DCF heat induced gels were *** results showed that the viscoelasticity,frequency dependence,and resistance strength of heat induced gels increased significantly with the increase of temperature and DCF *** degree of denaturation and water retention of heat induced gels increased significantly with increased variables within the temperature and variation windows of 75℃ to 95℃ and 13%to 21%.The CLSM results revealed that variations of both temperature and DCF variation could cause the proteins in the heat induced gels to aggregate gradually and to form protein *** temperature or variation exceeded certain value(85℃ or 17%),the protein aggregations broke up and the protein clusters became smaller and more ***,the heat induced gels presented better water holding capacity,viscoelasticity,structural stability and gel property at a temperature of 95℃ or a DCF variation of 21%within the present experimental range.

关键词： defatted chickpea flour rheological property freeze-thaw stability water holding capacity microstructure

APPLICATION OF MFCAV RIEMANN SOLVER TO MAIRE＇S CELL-CENTERED LAGRANGIAN METHOD

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Journal of Computational Mathematics 2015年第2期33卷 128-145页

作者： Yan Liu Baolin tian Weidong Shen Shuanghu Wang Song Jiang Dekang Mao Applied Physics and Computational Mathematics Beijing 100095 P. R. China Department of Mathematics Shanghai University Shanghai 200444 P. R China

In this paper, we apply arbitrary Riemann solvers, which may not satisfy the Maire＇s requirement, to the Maire＇s node-based Lagrangian scheme developed in [P. H. Maire et al., SIAM J. Sci. Comput, 29 （2007）, 1781-1824]. In particular, we apply the so-called Multi-Fluid Channel on Averaged Volume （MFCAV） Riemann solver and a Riemann solver that adaptively combines the MFCAV solver with other more dissipative Riemann solvers to the Maire＇s scheme. It is noted that neither of the two solvers satisfies the Maire＇s requirement. Numerical experiments are presented to demonstrate that the application of the two Riemann solvers is successful.

关键词： Maire's node-based Lagrangian scheme Riemann solvers Riemann invariants,weighted least squares procedure.

Numerical Simulation of a Viscoelastic Thinning Process for Preparing Flexible Glasses by Redrawing Method

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Journal of Wuhan University of Technology(Materials Science) 2023年第1期38卷 65-71页

作者：刘冰袁坚 GUO Zhenqiang ZHANG Qi HAN Zhuangzhuang TAN Jinqi tian Peijing ZHENG Weihong State Key Laboratory of Silicate Materials for Architectures Wuhan University of TechnologyWuhan 430070China Shahe Research Institute of Glass Technology Shahe 054100China BCMaterials Basque Center for MaterialsApplications and NanostructuresUPV/EHU Science Park48940 LeioaSpain IKERBASQUE Basque Foundation for SciencePlaza Euskadi5Bilbao48009Spain

The forming process of the flexible ultrathin glasses(UTG)prepared by the redrawing method was numerically simulated using ANSYS Polyflow *** the forming process by the redrawing method,temperature,viscosity,transverse and longitudinal velocity distribution of the glasses with different compositions were ***,the influence of these factors on the width and thickness of the flexible glass plate was *** is found that the internal and external heat exchange of glass has a dominant influence on the viscosity variation during the UTG forming process,which is inconsistent with the general viscosity-temperature *** glass that first reaches the lower limit of forming viscosity can significantly resist the shrinking effect caused by surface tension,making the glass wider during the *** the original glass width remains unchanged,the glass thickness or feeding speed is reduced,wider and thinner flexible glasses can be produced.

关键词： flexible ultra-thin glass(UTG) numerical simulation down-draw forming redrawing method