低价锆氧化物Zr_(3)O的结构、热力学和弹性性质第一性原理研究

采用第一性原理系统地研究3种Zr_(3)O晶形(空间群分别为R3c(斜方六面体)、R32(斜方六面体)和P6322(六面体))的晶格动力学及其与温度相关的热力学和力学性质。计算得到的3种Zr_(3)O晶形的晶体结构参数与实验结果一致。此外,证明3种Zr_(3)O结构在动力学和热力学上均具有稳定性。获得了3种Zr_(3)O晶形在0~1500 K温度范围内的熵、焓、吉布斯自由能、比热容、热膨胀系数和弹性模量等性质。发现3种Zr_(3)O晶形在0K时的相对稳定性顺序为Zr_(3)O(R3c)>Zr_(3)O(R32)>Zr_(3)O(P6_(3)22);然而,在50 K时Zr_(3)O(R3c)转变成Zr_(3)O(R32),在540K时转变为Zr_(3)O(P6_(3)22)。相较于其他2种Zr_(3)O相,Zr_(3)O(R32)表现出更优越的力学性能。

Fracture sealing performance of granular lost circulation materials at elevated temperature:A theoretical and coupled CFD-DEM simulation study

Lost circulation is a common downhole problem of drilling in geothermal and high-temperature,high-pressure(HTHP)formations.Lost circulation material(LCM)is a regular preventive and remedial measure for lost circulation.However,conventional LCMs seem ineffective in high-temperature formations.This may be due to the changes in the mechanical properties of LCMs and their sealing performance under high-temperature conditions.To understand how high temperature affects the fracture sealing performance of LCMs,we developed a coupled computational fluid dynamics-discrete element method(CFD-DEM)model to simulate the behavior of granular LCMs in fractures.We summarized the literature on the effects of high temperature on the mechanical properties of LCMs and the rheological properties of drilling fluid.We conducted sensitivity analyses to investigate how changing LCM slurry properties affected the fracture sealing efficiency at increasing temperatures.The results show that high temperature reduces the size,strength,and friction coefficient of LCMs as well as the drilling fluid viscosity.Smaller,softer,and less frictional LCM particles have lower bridging probability and slower bridging initiation.Smaller particles tend to form dual-particle bridges rather than single-particle bridges.These result in a deeper,tighter,but unstable sealing zone.Reduced drilling fluid viscosity leads to faster and shallower sealing zones.

Chromosome-level genome assembly of the glass catfish(Kryptopterus vitreolus)reveals molecular clues to its transparent phenotype

Glass catfish(Kryptopterus vitreolus)are notable in the aquarium trade for their highly transparent body pattern.This transparency is due to the loss of most reflective iridophores and light-absorbing melanophores in the main body,although certain black and silver pigments remain in the face and head.To date,however,the molecular mechanisms underlying this transparent phenotype remain largely unknown.To explore the genetic basis of this transparency,we constructed a chromosome-level haplotypic genome assembly for the glass catfish,encompassing 32 chromosomes and 23344 protein-coding genes,using PacBio and Hi-C sequencing technologies and standard assembly and annotation pipelines.Analysis revealed a premature stop codon in the putative albinism-related tyrp1b gene,encoding tyrosinase-related protein 1,rendering it a nonfunctional pseudogene.Notably,a synteny comparison with over 30 other fish species identified the loss of the endothelin-3(edn3b)gene in the glass catfish genome.To investigate the role of edn3b,we generated edn3b^(−/−)mutant zebrafish,which exhibited a remarkable reduction in black pigments in body surface stripes compared to wild-type zebrafish.These findings indicate that edn3b loss contributes to the transparent phenotype of the glass catfish.Our high-quality chromosome-scale genome assembly and identification of key genes provide important molecular insights into the transparent phenotype of glass catfish.These findings not only enhance our understanding of the molecular mechanisms underlying transparency in glass catfish,but also offer a valuable genetic resource for further research on pigmentation in various animal species.

Influence of aluminium nitride as a foaming agent on the preparation of foam glass-ceramics from high-titanium blast furnace slag

To effectively reuse high-titanium blast furnace slag （TS）, foam glass-ceramics were successfully prepared by powder sintering at 1000℃. TS and waste glass were used as the main raw materials, aluminium nitride （AIN） as the foaming agent, and borax as the fluxing agent. The influence of the amount of A1N added （lwt%-5wt%） on the crystalline phases, microstructure, and properties of the produced foam glass-ceramics was studied. The results showed that the main crystal phases were perovskite, diopside, and augite. With increasing A1N content, a transformation from diopside to augite occurred and the crystallinity of the pyroxene phases slightly decreased. Initially, the aver- age pore size and porosity of the foam glass-ceramics increased and subsequently decreased; similarly, their bulk density and compressive strength decreased and subsequently increased. The optimal properties were obtained when the foam glass-ceramics were prepared by adding 4wt% AIN.

Effect of sintering temperature on the microstructure and properties of foamed glass-ceramics prepared from high-titanium blast furnace slag and waste glass

Foamed glass-ceramics were prepared via a single-step sintering method using high-titanium blast furnace slag and waste glass as the main raw materials The influence of sintering temperature(900–1060℃) on the microstructure and properties of foamed glass-ceramics was studied. The results show that the crystal shape changed from grainy to rod-shaped and finally turned to multiple shapes as the sintering temperature was increased from 900 to 1060℃. With increasing sintering temperature, the average pore size of the foamed glass-ceramics increased and subsequently decreased. By contrast, the compressive strength and the bulk density decreased and subsequently increased. An excessively high temperature, however, induced the coalescence of pores and decreased the compressive strength. The optimal properties, including the highest compressive strength(16.64 MPa) among the investigated samples and a relatively low bulk density(0.83 g/cm^3), were attained in the case of the foamed glass-ceramics sintered at 1000℃.

Influence of CeO_2 addition on the preparation of foamed glass-ceramics from high-titanium blast furnace slag

Foamed glass-ceramics doped with cerium oxide（CeO_2）were successfully prepared from high-titanium blast furnace slag by one-step sintering.The influence of CeO_2 addition（1.5wt%–3.5wt%）on the crystalline phases,microstructure,and properties of foamed glass-ceramics was studied.Results show that CeO_2 improves the stability of the glass phase and changes the two-dimensional crystallization mechanism into three-dimensional one.XRD analysis indicates the presence of Ca（Mg,Fe）Si_2O_6 and Ca（Ti,Mg,Al）（Si,Al）_2O_（6 ）in all sintered samples.Added with CeO_2,Ti CeO_4 precipitates,and crystallinity increases,leading to increased thickness of pore walls and uniform pores.The comprehensive properties of foamed glass-ceramics are better than that of samples without CeO_2.In particular,the sample added with a suitable amount of CeO_2（2.5wt%）exhibits bulk density that is similar to and compressive strength（14.9 MPa）that is more than twice of foamed glass-ceramics without CeO_2.