Effect of Elastic Strains on Adsorption Energies of C,H and O on Transition Metal Oxides

Platinum(Pt)-based noble metal catalysts(PGMs)are the most widely used commercial catalysts,but they have the problems of high cost,low reserves,and susceptibility to small-molecule toxicity.Transition metal oxides(TMOs)are regarded as potential substitutes for PGMs because of their stability in oxidizing environments and excellent catalytic performance.In this study,comprehensive investigation into the influence of elastic strains on the adsorption energies of carbon(C),hydrogen(H)and oxygen(O)on TMOs was conducted.Based on density functional theory(DFT)calculations,these effects in both tetragonal structures(PtO_(2),PdO_(2))and hexagonal structures(ZnO,CdO),along with their respective transition metals were systematically explored.It was identified that the optimal adsorption sites on metal oxides pinpointed the top of oxygen or the top of metal atom,while face-centered cubic(FCC)and hexagonal close-packed(HCP)holes were preferred for the transition metals.Furthermore,under the influence of elastic strains,the results demonstrated significant disparities in the adsorption energies of H and O between oxides and transition metals.Despite these differences,the effect of elastic strains on the adsorption energies of C,H and O on TMOs mirrored those on transition metals:adsorption energies increased under compressive strains,indicating weaker adsorption,and decreased under tension strains,indicating stronger adsorption.This behavior was rationalized based on the d-band model for adsorption atop a metallic atom or the p-band model for adsorption atop an oxygen atom.Consequently,elastic strains present a promising avenue for tailoring the catalytic properties of TMOs.

Lowering Sodium-Storage Lattice Strains of Layered Oxide Cathodes by Pushing Charge Transfer on Anions

Due to a high energy density,layered transition-metal oxides have gained much attention as the promising sodium-ion batteries cathodes.However,they readily suffer from multiple phase transitions during the Na extraction process,resulting in large lattice strains which are the origin of cycledstructure degradations.Here,we demonstrate that the Na-storage lattice strains of layered oxides can be reduced by pushing charge transfer on anions(O^(2-)).Specifically,the designed O3-type Ru-based model compound,which shows an increased charge transfer on anions,displays retarded O3-P3-O1 multiple phase transitions and obviously reduced lattice strains upon cycling as directly revealed by a combination of ex situ X-ray absorption spectroscopy,in situ X-ray diffraction and geometric phase analysis.Meanwhile,the stable Na-storage lattice structure leads to a superior cycling stability with an excellent capacity retention of 84%and ultralow voltage decay of 0.2 mV/cycle after 300 cycles.More broadly,our work highlights an intrinsically structure-regulation strategy to enable a stable cycling structure of layered oxides meanwhile increasing the materials’redox activity and Nadiffusion kinetics.

Effect of Six Bacterial Strains on the Activity of Second Instar Larvae and Egg Hatching of Meloidogyne incognita

[Objectives]The paper was to screen effective biocontrol strains against Meloidogyne incognita.[Methods]The effect of six bacterial strains sourced from the research group s strain library on the activity of second instar larvae of M.incognita,as well as on egg hatching,was evaluated.[Results]The treatment of fermentation supernatant derived from the X-2 strain exhibited a pronounced lethal effect on M.incognita,with a corrected mortality rate reaching 97%within 72 h.Additionally,this treatment significantly inhibited egg hatching,achieving an inhibition rate of 94.69%at a 20-fold dilution.The strain was identified as Bacillus velezensis,belonging to the genus Bacillus,and was designated as RKN1111.[Conclusions]This study presents alternative strains and a theoretical framework for the biological control of M.incognita.

Polyethylene glycol fusion repair of severed sciatic nerves accelerates recovery of nociceptive sensory perceptions in male and female rats of different strains

Successful polyethylene glycol fusion(PEG-fusion)of severed axons following peripheral nerve injuries for PEG-fused axons has been reported to:(1)rapidly restore electrophysiological continuity;(2)prevent distal Wallerian Degeneration and maintain their myelin sheaths;(3)promote primarily motor,voluntary behavioral recoveries as assessed by the Sciatic Functional Index;and,(4)rapidly produce correct and incorrect connections in many possible combinations that produce rapid and extensive recovery of functional peripheral nervous system/central nervous system connections and reflex(e.g.,toe twitch)or voluntary behaviors.The preceding companion paper describes sensory terminal field reo rganization following PEG-fusion repair of sciatic nerve transections or ablations;howeve r,sensory behavioral recovery has not been explicitly explored following PEG-fusion repair.In the current study,we confirmed the success of PEG-fusion surgeries according to criteria(1-3)above and more extensively investigated whether PEG-fusion enhanced mechanical nociceptive recovery following sciatic transection in male and female outbred Sprague-Dawley and inbred Lewis rats.Mechanical nociceptive responses were assessed by measuring withdrawal thresholds using von Frey filaments on the dorsal and midplantar regions of the hindpaws.Dorsal von Frey filament tests were a more reliable method than plantar von Frey filament tests to assess mechanical nociceptive sensitivity following sciatic nerve transections.Baseline withdrawal thresholds of the sciatic-mediated lateral dorsal region differed significantly across strain but not sex.Withdrawal thresholds did not change significantly from baseline in chronic Unoperated and Sham-operated rats.Following sciatic transection,all rats exhibited severe hyposensitivity to stimuli at the lateral dorsal region of the hindpaw ipsilateral to the injury.However,PEG-fused rats exhibited significantly earlier return to baseline withdrawal thresholds than Negative Control rats.Furthermore,PEG-fused rats with significantly improved Sciatic Functional Index scores at or after 4 weeks postoperatively exhibited yet-earlier von Frey filament recove ry compared with those without Sciatic Functional Index recovery,suggesting a correlation between successful PEG-fusion and both motor-dominant and sensory-dominant behavioral recoveries.This correlation was independent of the sex or strain of the rat.Furthermore,our data showed that the acceleration of von Frey filament sensory recovery to baseline was solely due to the PEG-fused sciatic nerve and not saphenous nerve collateral outgrowths.No chronic hypersensitivity developed in any rat up to 12 weeks.All these data suggest that PEG-fusion repair of transection peripheral nerve injuries co uld have important clinical benefits.

HIV-1 Transmission among Injecting Drug Users is Principally Derived from Local Circulating Strains in Guangxi, China

Objective The mode of human immunodeficiency virus(HIV) transmission via injection drug use(IDU)still exists, and the recent shift in IDU-related transmission of HIV infection is largely unknown. The purpose of this study was to analyze the spatiotemporal sources and dynamics of HIV-1 transmission through IDU in Guangxi.Methods We performed a molecular epidemiological investigation of infections across Guangxi from2009 to 2019. Phylogenetic and Bayesian time-geographic analyses of HIV-1 sequences were performed to confirm the characteristics of transmission between IDUs in combination with epidemiological data.Results Among the 535 subjects, CRF08_BC(57.4%), CRF01_AE(28.4%), and CRF07_BC(10.7%) were the top 3 HIV strains;72.6% of infections were linked to other provinces in the transmission network;93.6% of sequence-transmitted strains were locally endemic, with the rest coming from other provinces,predominantly Guangdong and Yunnan;92.1% of the HIV transmission among people who inject drugs tended to be transmitted between HIV-positive IDUs.Conclusion HIV recombinants were high diversity, and circulating local strains were the transmission sources among IDUs in Guangxi. However, there were still cases of IDUs linked to other provinces.Coverage of traditional prevention strategies should be expanded, and inter-provincial collaboration between Guangxi, Yunnan, and Guangdong provinces should be strengthened.

Antibacterial Properties of Crateva adansonii (Capparidaceae) on Strains Isolated from Chronic Wounds Diagnosed in the Commune of Ouinhi in 2021

Plants have always been used by people for therapeutic purposes. They are still the main source of therapeutic substances in developing countries. Crateva adansonii, a member of the Capparidaceae family, is a medicinal plant with antibacterial properties used in Benin. The aim of this study was to assess the efficacy of an aqueous extract of C. adansonii on bacterial strains isolated from chronic wounds in the Ouinhi population. To achieve this, the bacterial flora present in chronic wounds was identified using the Ikram method (2014) coupled with the API Remoel One method. The antibacterial properties of the aqueous extract of C. adansonii on the microbial strains isolated were then assessed by determining the Inhibition Diameters (ID), the Minimum Inhibitory Concentrations (MIC) and finally the Minimum Bactericidal Concentrations (MBC). A total of eighty (80) strains were isolated and identified on the basis of morphological, cultural and biochemical characteristics. The species S. Aureus species accounted for the largest proportion (67.5%). Other species such as Listeria sp, Pseudomonas proteus, S. epidermidis and Bacillus cereus, Citrobacter freundii, Steno maltophila;Axin calcoaceticus, E. coli, K. pneumonia, Lem. richardii, Salmonella paratyphi A, Salmonella sp, Shigella sp were determined in variable proportions. At a concentration of 10 mg/ml, only S. aureus was sensitive to contact with the extract. However, at 20 mg/ml, 89% of strains were sensitive and 11% very sensitive. The highly sensitive strains are Salmonella sp and E. coli. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) are 20 mg/ml and 40 mg/ml respectively. The MBC/MIC ratio of the aqueous mixture of Crateva adansonii (Capparidaceae) varied from 1.2 to 2, with a bactericidal effect on 100% of the strains tested.

Analysis of Population Genetic Change to Single Oospore Strains of Phytophthora infestans

The occurrence of sexual reproduction accelerates the population genetic variation of Phytophthora infestans and makes it more difficult to control.The systematic analysis of the differentiation of phenotype(mating type and metalaxyl sensitivity)and genotype(mtDNA haplotype and SSR genotype)of 65 single oospore strains of P.infestans was carried out in this article.Five test strains were isolated from Heilongjiang Province and Mongolia Autonomous Region.The experiment results showed that the isolation ratio of metalaxyl resistance(MR:HR)of single oospore strains produced through the cross of medium resistance and high resistant parents was 18:13;the isolation ratio of the metalaxyl resistance(S:MR:HR)of single oospore strains produced through the cross of sensitive and high resistant parents was 4:12:7.The progenies of single oospore strains produced through self-fertility parents with medium resistance were all of the medium resistance.The mating types A1:A2 was greater than 1:1 in single oospore strains of the progenies,which did not conform to the Mendel's law of inheritance.All single oospore strains of the progenies inherited mitochondrial DNA fragments from only one parent.Sexual recombination of single oospore strains was verified by using two pairs of SSR primers(Pi4B and Pi4G).At the locus of Pi4B and Pi4G in the cross of KS-37 and KS-25,the separation frequencies of allele were 19:12 and 14:17,respectively.They produced two new genotype strains.This study could provide a basis for formulating disease control strategies.

Development of a Test Rig for Axial Strains Measurement in Automobile Wheel

In automobile wheel application, a test rig is vital and used to simulate conditions of the wheel in service in order to affirm the safety and reliability of the wheel. The present work designed a test rig for measuring axial strains in automobile wheel. The wheel used was a five-arm wheel (6JX14H2;ET 42) and Tyre (175 × 65 R 14). Experimental (EXP) test was carried out, with a radial load of 4750 N and inflation pressure of 0.3 MPa, to measure the axil strains which were converted to maximum principal strain values and, compared with data from Finite Element Analysis (FEA) using Creo-Element/Pro 5.0 at wheel’s contact angles of 90 degree (FEA 90 deg), 40 degree (FEA 40 deg) and 30.25 degree (FEA 30.25 deg), respectively. Results show that at the wheel’s point of contact with the ground, maximum principal strain values were highest at the inboard bead seat with a value of about 5.69 × 10-4 mm/mm, followed by the values at the well of about 5.66 × 10-4 mm/mm. The value at the outboard bead seat was least at about 2.22 × 10-4 mm/mm, which was due to the presence of spikes at this location that tends to resist imposed radial loads. However, the highest mean maximum principal strain values at the locations of inboard, well and outboard, were about 2.11 × 10-4 mm/mm, 3.78 × 10-4 mm/mm and .99 × 10-4 mm/mm, respectively. With the highest single value of about 5.69 × 10-4 mm/mm, the inboard bead seat was the most strained location of the wheel. Overall results showed that all values of maximum principal strains were below the threshold value of about 1 × 10-2 mm/mm. The values obtained for EXP and FEA could be said to be in close agreement when compared with the threshold value. With this in mind, the rig is recommended for use in related experimental procedures.

软枣猕猴桃新品系“蜜玉”的选育

“蜜玉”是从软枣猕猴桃混合实生后代中筛选出的优良资源,经无性繁殖选育出的软枣猕猴桃新品系。“蜜玉”果实椭圆形,果皮绿色,光滑无毛,平均单果质量12.1 g。果肉绿色,可溶性固形物22.5%,总糖13.4%,总酸1.06%,维生素C 1050.0 mg/kg。口感较甜,香气浓郁,抗寒、抗病能力较强。在吉林左家地区,6月中旬开花,9月初成熟。果实在常温条件下第7天开始软熟,低温(2~4℃)条件下第24天开始软熟。

腊肉源酵母菌对发酵牛肉品质特性的影响

在发酵牛肉加工中,添加源于河南信阳腊肉的季巴蒙毕赤酵母以及四川绵阳腊肉的汉逊德巴利酵母作为发酵菌株,以研究特色腊肉源单菌株发酵对发酵牛肉品质的影响,选择地方特色产品和空白作为对照,进行产品水分含量、水分活度(aw)、pH值、蛋白质含量、亚硝胺含量、质构及感官评价等特性指标的测定与分析。结果表明,两株菌株单菌株发酵牛肉硬度适中,弹性和咀嚼性显著高于传统产品,其整体可接受性和传统腊肉未见显著差异,而且水分含量,pH值与亚硝胺含量显著低于传统腊肉制品。综合分析显示两种酵母菌均可作为发酵剂用于发酵肉制品生产,以提升产品品质和安全性。

特色腊肉源细菌发酵剂对发酵牛肉品质的影响

目的:研究特色腊肉源细菌对发酵牛肉品质的影响。方法:将来自于湖南湘西腊肉的马葡萄球菌和来自信阳腊肉的肠膜明串珠菌作为发酵菌株,生产发酵牛肉,并将其与地方特色产品及空白组进行对比,分析产品的水分含量、水分活度、pH、蛋白质含量、色泽、质构及感官评价、N-亚硝胺类物质含量等品质指标的差异性。结果:两株菌株单菌株发酵产品亚硝胺含量,显著低于传统腊肉制品(P<0.05);弹性显著高于传统产品(P<0.05);肠膜明串珠菌发酵产品咀嚼性和四川腊肉没有显著性差异(P>0.05);马葡萄球菌发酵产品的硬度显著低于其他处理组(P<0.05),且马葡萄球菌发酵产品的整体接受性最高,但四川绵阳腊肉及湖南湘西腊肉的整体可接受性没有显著差异性(P>0.05)。结论:两种菌株对发酵产品品质影响不同,但都可以作为发酵剂应用于肉制品加工,未来可以考虑将两种菌株进行复配发酵,综合改善产品品质,提高产品安全性。

等应变条件下增压式真空预压固结解析解

从注气增压对土体作用效果的角度出发,建立增压式真空预压固结解析理论模型。提出基于注气增压压力等效的受力简化模型;引入新参数——径向渗透系数增大系数η,反映注气过程对土体渗透性质的改变。根据Barron等应变假定和达西定律,考虑排水板涂抹效应与井阻作用、土体径-竖向渗流以及上部堆载,推导增压式真空预压固结控制方程及其解析解,并利用弹性力学方法推导等效注气增压压力p(t)的计算公式。针对瞬时增压和线性增压两种特例给出具体解析解公式,并通过与工程案例对比分析,验证了解析解及等效力计算方法的合理性。通过对固结性状的分析得出如下结论:注气增压方法可增大土体负孔隙水压力值,加速土体排水固结;“参数η”对固结速率的影响较大,分析模型中考虑注气过程对径向渗透系数的改变会更加合理;井阻作用会导致土体固结速率减慢,径-竖向渗流时孔压能够消散完成,而只有径向渗流时孔压无法消散完成。

库水作用下滑坡土体渗流与蠕变耦合试验研究

水库滑坡变形具有显著的渗流与蠕变耦合效应。为此,采用自主研发的渗流与蠕变耦合三轴试验仪,分别开展了渗流对蠕变的影响以及变形对渗流的影响试验研究,并改进GDS三轴仪完成了高精度控制和量测的渗流与蠕变耦合试验。结果表明:渗流作用下,土样体积变形随时间先逐渐增大后缓慢减小,主要原因是超孔隙水压力导致围压卸荷,使得土样产生回弹变形,但渗透压力持续作用于土体,使得土样体积持续缓慢减小;获取了渗流过程中土样体积的变化结果,分别建立了渗流开始前试样e-k(孔隙比-渗透系数)关系曲线及渗流稳定后试样e-k关系曲线,结果表明考虑变形影响的e-k关系曲线更能反映土体的流固耦合效应。研究成果可望为水库滑坡变形演化预测提供更加科学严密的理论和方法。

土工格栅加筋粉煤灰改良黄土力学特性研究

随着西部黄土地区城镇化进程的加快,填挖结合的新增用地方式要求地基处理技术需要重点解决填方区的强度与变形问题。论文将粉煤灰作为改性填料对黄土进行改良,通过直剪试验、三轴试验、湿陷试验与扫描电镜试验,分析不同粉煤灰掺入比条件下加筋与未加筋黄土试样的强度变化规律、宏观破坏特征和微结构特征。结果表明:采用粉煤灰改良和土工格栅加筋后,黄土的最优含水率增大,最大干密度降低。当粉煤灰掺入比λ=20%时,加筋改良效果最好,黄土的峰值强度、残余强度和等效内摩擦角均有大幅提高,侧向变形显著减小,且能有效降低其湿陷性。微结构分析表明:粉煤灰对黄土的改良主要体现在颗粒直接填充和化学结晶体交织成的网状填充两种类型的强化作用,改良后黄土的孔隙率与孔隙尺寸均有所下降。研究结果可为黄土地区填方边坡与填方路基的改良加固提供参考。

甘露醇对草菇继代菌株生产性状和ROS清除能力的影响

【目的】研究甘露醇对草菇继代菌株的生产性状和活性氧(ROS)清除能力的影响,探索一种简便、有效的草菇退化菌种复壮方法。【方法】以笔者课题组前期获得的组织分离继代菌株T6、T12、T19为试验菌株,T6为连续继代6次,T12为连续继代12次,T19为连续继代19次;草菇原种V844(T0)为商业栽培种。将传统马铃薯葡萄糖琼脂培养基(PDA)中的葡萄糖替换为等质量的甘露醇,进行菌丝生理性状测定;在栽培基质中添加甘露醇,测定子实体农艺学性状;以硝基四氮唑蓝(NBT)染色、超氧阴离子(O_(2))、过氧化氢(H_(2)O_(2))含量反映活性氧(ROS)积累;采用实时荧光定量PCR(RT-qPCR)测定抗氧化酶基因表达量;利用试剂盒测定抗氧化酶活力;通过菌丝染色法测定细胞核数量和线粒体膜电位;利用高效液相色谱仪(HPLC)测定菌丝能量指标。【结果】甘露醇处理对未退化菌株T0、T6的影响不显著,但能有效恢复草菇退化菌株T12、T19的生产性状和ROS清除能力。甘露醇使T12、T19的菌丝生长速度分别提高31.46%、20.99%,菌丝生物量分别提高97.33%、76.36%;使T12的生产周期缩短12.24%,生物学效率提高17.97%,恢复至T0水平;并使退化严重、失去出菇能力的T19重新长出子实体。同时,甘露醇使T12、T19的Cu/Zn超氧化物歧化酶基因(Cu/Zn-sod)相对表达量分别上调24.64%和61.54%,Mn-sod2相对表达量分别上调19.76%和267.09%,谷胱甘肽过氧化物酶基因(gpx)相对表达量分别上调25.67%和55.82%,并使SOD活力分别提高10.79%和72.32%,GPX活力分别提高16.98%和103.85%;使T12、T19中的ROS积累量显著降低,T12、T19中的O_(2)含量分别下降35.96%和41.62%,H_(2)O_(2)含量分别下降14.44%和18.26%;并使T12、T19的细胞核数目和线粒体膜电位显著增加;使T12、T19中的ATP含量分别提高17.08%和14.55%,EC值分别提高4.52%和0.92%。【结论】甘露醇能显著提高草菇退化菌株T12、T19的抗氧化能力和线粒体功能,并有效恢复其生产性状。

泸定M S6.8地震震前变形特征及鲜水河断裂南东段地震活动性

针对鲜水河断裂带南东段的历史地震活动性和近10 a该断裂带上发生的中小震群展布特征,利用GNSS观测数据给出2022年泸定M S6.8地震震源区及周边区域的速度场、应变率场,识别此次地震震前的变形特征。GNSS速度场显示,鲜水河断裂带南东段走滑速率约为10 mm/a,区域整体运动为ES向,与断裂构造运动具有一致性;应变率场结果显示,发震断裂仍存在较强的剪切应变积累,汶川特大地震后随着应变能不断释放,龙门山断裂带的卸载作用间接影响鲜水河断裂带的南东段,该断裂长期处于应变积累高值的过渡区,现今仍具有较高的断层闭锁状态,该地区的地震活动趋势和地震危险性值得进一步关注和研究。

越南非洲猪瘟疫苗AVAC ASF LIVE(ASFV-G-ΔMGF)研究工作分析与思考

非洲猪瘟(Afcrian swine fever,ASF)是由非洲猪瘟病毒(African swine fever virus,ASFV)感染引起的烈性传染病。近日,越南正式将经临床试验验证的非洲猪瘟弱毒疫苗AVAC ASF LIVE(ASFV-G-ΔMGF)在其全国推广使用。本文对越南非洲猪瘟弱毒疫苗ASFV-G-ΔMGF相关研究数据进行了总结分析,分别从ASFVG-ΔMGF株攻毒保护能力评价、传代细胞培养株临床动物实验、野猪口服接种试验、毒力返强验证等方面,结合国内相关ASFV基因缺失株试验数据进行了分析。总结分析发现:越南上市的ASFV-G-ΔMGF疫苗株,二次免疫接种后攻毒保护效果更好,但在对野猪的口服接种评价中,其口鼻接种效果存在不确定性;随着疫苗株在动物体内的不断传代,其存在毒力返强和毒株变异风险,导致接种猪只临床症状明显;ASFV-G-ΔMGF株虽然有较好的攻毒保护能力和可靠的生产优势,但仍缺乏相关研究数据,特别是在垂直传播、交叉保护、基因突变等方面。后续仍需对ASFV-G-ΔMGF株的临床应用效果进一步评价。

羊肚菌栽培方法优化研究

为了探究不同环境条件对羊肚菌产量和品质的影响,分别研究了品种、单播混播、菌种形态、低畦、腐殖质添加量等因素对羊肚菌生产性能的影响。选取ZHS-3、ZHS-5、四川-6和MZ-8等品种,在冬春季节分别做了品比试验、单一菌种和混合菌种栽培试验、固体菌种和液体原种栽培试验、低畦栽培试验和土壤基质栽培试验。结果表明,品比试验中四川-6的栽培效果更好,较ZHS-3、ZHS-5和MZ-8产量分别高22.27%、32.17%和19.74%;单一菌种和混合菌种栽培试验中单一菌种的栽培效果更好,产量较混合菌种高22.72%,说明若早发菌种和晚发菌种同时存在则无协同作用;液体原种和固体菌种栽培试验中固体菌种的栽培效果更好,产量较液体菌种高28.78%,液体菌种虽然发菌快但个体小;低畦栽培试验中平栽的栽培效果更好,产量较下挖组高53.24%,说明通风不足会影响产量;腐殖质添加试验中添加腐殖质含量在5%时栽培效果更好,产量较添加10%腐殖质区域高20.10%,较对照组高31.12%,说明腐殖质添加不宜过量。

砂岩冻结/解冻过程蠕变特性研究

寒区岩体长期经受荷载与冻融的共同作用,若不考虑冻融过程对其长期力学行为的影响,将会给寒区工程建设和安全运营带来重大的安全隐患。为此,以寒区某边坡工程砂岩为研究对象,通过开展不同冻结温度下的冻结/解冻过程单轴分级加载蠕变试验,使岩石在同一应力状态下处于冻结和解冻过程,真实再现寒区工程岩体长期力学响应特征。以此研究冻结/解冻过程对岩体长期力学特性的影响,并对其蠕应变、稳态蠕变速率及长期强度等宏观力学指标进行量化分析。结果表明:(1)砂岩冻结过程先后经历冷缩阶段、冻胀阶段和稳态蠕变阶段,解冻过程只经历融缩阶段和稳态蠕变阶段;冷缩阶段和融缩阶段砂岩发生收缩变形,冻胀阶段则发生膨胀变形;(2)冻结/解冻温度为-5℃/25℃、-10℃/25℃、-15℃/25℃时,砂岩蠕应变较常温状态下蠕应变增幅范围分别为102%~193%、81%~126%、105%~194%,解冻后稳态蠕变速率较冻结前最大增长3.65倍、4.31倍、5.56倍,冻结/解冻过程蠕变砂岩的长期强度是常温状态下长期强度的96.33%、88.52%、75.44%;(3)应力对冷缩、冻胀变形的产生起抑制作用而对融缩变形的产生起促进作用;冻结温度越低,冻胀变形和解冻后融缩变形越明显。文章提出的将蠕变与冻融过程相结合的试验方法能较为真实地反映工程实际,该方法为寒区岩体工程长期稳定性评价提供新途径。

承压容器内甲烷爆炸及泄爆特性研究

开展了中低压和高压工况下甲烷空气爆炸及泄爆试验,分析了爆炸及泄爆过程压力、压升速率等参数变化规律。结果表明,在低压工况下,甲烷体积分数达到12%时,不同初压下升压速率均不超过10 MPa/s。体积分数小于11%时,最大爆炸压力与体积分数近似呈二次函数的关系,大于11%时最大爆炸压力明显下降。在高压工况下,低体积分数的甲烷对于升压速率的影响更为显著,各个初压下升压速率基本相同。当采用直径100 mm反拱开槽爆破片进行泄爆时,在低升压速率工况下,反拱带槽爆破片在各个工况下均有较好的动态响应能力,在高升压速率工况下,爆破片的动态响应能力降低。分析了不同应变率下爆破片断口形态的变化,低升压速率工况下断口为韧性断裂,在高升压速率下断口向脆性断裂转变。