Liquefaction and post-liquefaction behaviors of sands affected by immersion-induced degradation of crushed mudstone

A series of undrained triaxial tests was conducted to investigate the effect of crushed mudstone with the immersion-induced degradation on the liquefaction and post-liquefaction properties,and the undrained shearing behavior without precedent cyclic-loading histories of sands containing crushed mudstone.The tested materials with a main particle diameter of 2-0.85 mm were prepared by mixing sands and crushed mudstone to reach the prescribed mudstone content defined by dry mass ranging from 0% to 50%.The mixtures were subjected to immersion under a certain stress level and were subsequently tested.In addition,one-dimensional compression tests were also supplementally performed to visually observe the immersion-induced degradation of crushed mudstone.The test results mainly showed that: (1) the liquefaction resistance,the post-liquefaction undrained strength,and the undrained strength without a precedent cyclic-loading history decreased significantly with increasing mudstone content,M c ,up to 20%;(2) even a small amount of crushed mudstone affected these strengths;(3) the above-mentioned large reductions in the strengths were attributed to the immersion-induced degradation of crushed mudstone;(4) at M_(c) >20%,the liquefaction resistance increased while the significant increase in the undrained static strengths with and without precedent cyclic-loading histories was not observed;and (5) the increase in the liquefaction resistance at M_(c) >20% may have been attributed to both the gradual increase in the plasticity and the formation of the soil aggregates among deteriorated crushed mudstone,while the increase in the specimen density did not play an important role in such behavior.

Discussion on Dust Removal(Suppression)System of Crushing Station in Open-Pit Coal Mine

This paper introduces the method of coal dust treatment in crushing station and the present situation of dust removal system in typical open-pit coal mine crushing station in China,and expounds the research idea of determining comprehensive dust removal(suppression)system in crushing station inspired by the working principle of"range hood".Based on the design example and link optimization of the crush-ing station of open-pit coal mine I of Thar coalfield,this paper finally draws some conclusions on the key technologies of dust removal(suppression)system of open-pit coal mine crushing station.This study has certain reference value for the technical innovation of dust removal(suppression)system in crushing station,the realization of green mining in"crushing link",and the reduction and avoidance of ecological environment pollution in mining area.

IVUS引导下Step-Crush术治疗左主干分叉病变对支架贴壁情况及患者预后的影响

目的:分析血管内超声(IVUS)引导下Step-Crush术治疗左主干分叉病变对支架贴壁情况及患者预后的影响。方法:回顾分析2021年3月—2022年12月于九江市第一人民医院总院心血管内科就诊的左主干分叉病变患者60例,根据手术方式将患者分为IVUS组(n=34,采用IVUS引导下StepCrush术)和常规组(n=26,采用常规Step-Crush术)。对比两组支架情况(最大支架直径、左主干支架长度、支架贴壁不良发生率、支架边缘夹层发生率)、球囊参数(球囊最大直径、球囊最大压力)、心功能指标[左室射血分数(LVEF)、左室舒张末内径(LVEDD)]及心血管不良事件发生率。结果:相较于常规组,IVUS组最大支架直径、左主干支架长度、球囊最大直径均更长,球囊最大压力更大(P<0.05);术后2个月,IVUS组LVEF较常规组更高,LVEDD较常规组更低,差异均有统计学意义(P<0.05);IVUS组支架贴壁不良发生率、心血管不良事件发生率均更低,差异均有统计学意义(P<0.05)。两组支架边缘夹层发生率对比,差异无统计学意义(P>0.05)。结论:IVUS应用于Step-Crush术中可改善左主干分叉病变患者支架置入情况,降低支架贴壁发生率,有效预防心血管不良事件发生。

Dynamic crushing behaviors and enhanced energy absorption of bio-inspired hierarchical honeycombs with different topologies

In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs(BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element(FE) analysis.Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional(1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs.

Valproate reduces retinal ganglion cell apoptosis in rats after optic nerve crush

The retinal ganglion cells of the optic nerve have a limited capacity for self-repair after injury.Valproate is a histone deacetylase inhibitor and multitarget drug,which has been demonstrated to protect retinal neurons.In this study,we established rat models of optic nerve-crush injury and injected valproate into the vitreous cavity immediately after modeling.We evaluated changes in the ultrastructure morphology of the endoplasmic reticulum of retinal ganglion cells over time via transmission electron microscope.Immunohistochemistry and western blot assay revealed that valproate upregulated the expression of the endoplasmic reticulum stress marker glucose-regulated protein 78 and downregulated the expression of transcription factor C/EBP homologous protein,phosphorylated eukaryotic translation initiation factor 2α,and caspase-12 in the endoplasmic reticulum of retinal ganglion cells.These findings suggest that valproate reduces apoptosis of retinal ganglion cells in the rat after optic nerve-crush injury by attenuating phosphorylated eukaryotic translation initiation factor 2α-C/EBP homologous protein signaling and caspase-12 activation during endoplasmic reticulum stress.These findings represent a newly discovered mechanism that regulates how valproate protects neurons.

Effects of coals microscale structural features on their mechanical properties,propensity to crushing and fine dust formation

The work is dedicated to revealing the structural features of coals with different ranks,such as anthracites,metaanthracite and graphite,that determine their ability to crush and form fine dust.For this purpose,a combination of various nanoin-dentation techniques and Raman spectroscopy was used.The mechanical behavior of the selected coals was investigated by cyclic nanoindentation with increasing peak load and quasi-static loading.The alteration of the mechanical properties was studied by analysis of elastic moduli and damage indices Rw.Three groups of coals were identified based on their propensity to crushing during cyclic nanoindentation.Coals assigned to the first and second groups are characterized by local destruction in the contact zone with the indenter and the formation of a core of crushed material.Coals assigned to the third group are characterized by bulk destruction(outside the zone of contact with the indenter).In general,the ability of coals to fracture under mechanical loading decreases in the series of metamorphism due to microscale compaction of vitrinite matter.In the series of anthracite,metaanthracite and graphite,it is established that the coal matter compaction takes place for the anthracite and metaanthracite,whereas graphite reveals rather different behavior due to abrupt change of its structure.The ratios between the amorphous and crystalline phases of carbon(S)were determined by deconvolution of coals Raman spectra.The propensity of coals to crushing(a damage index Rw)increases with growth of the proportion of amorphous carbon in the coal matter.For the considered coals and metaanthracite,it is established that the proneness to destruction outside the contact zone with the indenter is determined by the ratio of amorphous and crystalline carbon of 1 and higher.When S parameter is lower than 1,the coals are being crushed only in the zone of contact with the indenter.

Dynamic crushing behavior and energy absorption of hybrid auxetic metamaterial inspired by Islamic motif art

Auxetic honeycomb structures are promising metamaterials with outstanding mechanical properties,and can be potentially used in energy absorption applications.In this study,a novel modified re-entrant hybrid auxetic metamaterial inspired by Islamic motif art is designed by integrating four-pointed double re-entrant motifs with symmetric semi-hexagonal unit cells to achieve a high energy absorption capacity(EAC).Theoretical analyses and numerical simulations are performed to examine the dynamic crushing behavior of the four-pointed double re-entrant combined structure(FDRCS).The developed finite element models(FEMs)are validated by the experiments under quasi-static compression.The deformation mode and stress-strain curves are further studied under low,medium,and high crushing velocities.The theoretically predicted plateau stress of the FDRCS under different crushing velocities is consistent with the numerical simulation results.The crushing stress and the EAC of the FDRCS are influenced by the geometric parameters and crushing velocities.The FDRCS exhibits a negative Poisson's ratio(NPR),owing to the four-point re-entrant structure(RES).Moreover,the specific energy absorption(SEA)of these structures is higher than that of nonauxetic hexagonal and auxetic re-entrant structures,owing to the generation of more plastic hinges that dissipate more energy during dynamic crushing.

Charcot-Marie-Tooth-1A and sciatic nerve crush rat models:insights from proteomics

The sensorimotor and histological aspects of peripheral neuropathies were already studied by our team in two rat models:the sciatic nerve crush and the Charcot-Marie-Tooth-1A disease.In this study,we sought to highlight and compare the protein signature of these two pathological situations.Indeed,the identification of protein profiles in diseases can play an important role in the development of pharmacological targets.In fact,Charcot-Marie-Tooth-1A rats develop motor impairments that are more severe in the hind limbs.Therefore,for the first time,protein expression in sciatic nerve of Charcot-Marie-Tooth-1A rats was examined.First,distal sciatic nerves were collected from Charcot-Marie-Tooth-1A and uninjured wild-type rats aged 3 months.After protein extraction,sequential window acquisition of all theoretical fragment ion spectra liquid chromatography and mass spectrometry was employed.445 proteins mapped to Swiss-Prot or trEMBL Uniprot databases were identified and quantified.Of these,153 proteins showed statistically significant differences between Charcot-Marie-Tooth-1A and wild-type groups.The majority of these proteins were overexpressed in Charcot-Marie-Tooth-1A.Hierarchical clustering and functional enrichment using Gene Ontology were used to group these proteins based on their biological effects concerning Charcot-Marie-Tooth-1A pathophysiology.Second,proteomic characterization of wild-type rats subjected to sciatic nerve crush was performed sequential window acquisition of all theoretical fragment ion spectra liquid chromatography and mass spectrometry.One month after injury,distal sciatic nerves were collected and analyzed as described above.Out of 459 identified proteins,92 showed significant differences between sciatic nerve crush and the uninjured wild-type rats used in the first study.The results suggest that young adult Charcot-Marie-Tooth-1A rats(3 months old)develop compensatory mechanisms at the level of redox balance,protein folding,myelination,and axonogenesis.These mechanisms seem insufficient to hurdle the progress of the disease.Notably,response to oxidative stress appears to be a significant feature of Charcot-Marie-Tooth-1A,potentially playing a role in the pathological process.In contrast to the first experiment,the majority of the proteins that differed from wild-type were downregulated in the sciatic nerve crush group.Functional enrichment suggested that neurogenesis,response to axon injury,and oxidative stress were important biological processes.Protein analysis revealed an imperfect repair at this time point after injury and identified several distinguishable proteins.In conclusion,we suggest that peripheral neuropathies,whether of a genetic or traumatic cause,share some common pathological pathways.This study may provide directions for better characterization of these models and/or identifying new specific therapeutic targets.

Crushing Mechanism of Spherical Tungsten Alloy Fragments Penetrate Thick Steel Plate Target

Against protection requirements for high-speed fragments on the ground weapons,we carried out the research work of crushing mechanism at different impact speeds ofφ8.7 mm spherical tungsten alloy,the penetration to 603 armor steel was completed by 20 mm ballistic gun,and the ANSYS/LS-DYNA software was used to complete the numerical calculation of the penetration.We find that there are different crushing mechanisms of spherical tungsten alloy with different speeds and low speed,the crushing mechanism of fragment is mainly controlled by overall plastic deformation,shearing stripping,and squeezing at a high pressure and a high speed.The crushing mechanism will have a spallation phenomenon in addition to the crushing mechanism under high pressure.

Use of a tissue clearing technique combined with retrograde trans-synaptic viral tracing to evaluate changes in mouse retinorecipient brain regions following optic nerve crush

Successful establishment of reconnection between retinal ganglion cells and retinorecipient regions in the brain is critical to optic nerve regeneration.However,morphological assessments of retinorecipient regions are limited by the opacity of brain tissue.In this study,we used an innovative tissue cleaning technique combined with retrograde trans-synaptic viral tracing to observe changes in retinorecipient regions connected to retinal ganglion cells in mice after optic nerve injury.Specifically,we performed light-sheet imaging of whole brain tissue after a clearing process.We found that pseudorabies virus 724(PRV724)mostly infected retinal ganglion cells,and that we could use it to retrogradely trace the retinorecipient regions in whole tissue-cleared brains.Unexpectedly,PRV724-traced neurons were more widely distributed compared with data from previous studies.We found that optic nerve injury could selectively modify projections from retinal ganglion cells in the hypothalamic paraventricular nucleus,intergeniculate leaflet,ventral lateral geniculate nucleus,central amygdala,basolateral amygdala,Edinger-Westphal nucleus,and oculomotor nucleus,but not the superior vestibular nucleus,red nucleus,locus coeruleus,gigantocellular reticular nucleus,or facial nerve nucleus.Our findings demonstrate that the tissue clearing technique,combined with retrograde trans-synaptic viral tracing,can be used to objectively and comprehensively evaluate changes in mouse retinorecipient regions that receive projections from retinal ganglion cells after optic nerve injury.Thus,our approach may be useful for future estimations of optic nerve injury and regeneration.

大豆玉米带状种植模式下玉米摘穗机设计与试验

针对丘陵山区大豆玉米带状种植模式的玉米果穗收获有机难用、无机可用的现状,设计一款自走式小型玉米摘穗机。该机采用纵卧式摘穗辊实现果穗摘取,并通过输送装置收集装袋;采用“Y”型布局的L型小甩刀实现茎秆粉碎。对摘穗过程进行动力学分析、对粉碎过程进行静力学分析,确定其核心装置设计参数并进行样机试制。以茎秆粉碎长度合格率、果穗损失率、籽粒破碎率为试验指标进行田间试验,来验证该机设计的合理性。试验表明:在生产率为0.8 hm^(2)/d、果穗籽粒含水率为26.38%、茎秆含水量为71.25%的条件下进行试验,茎秆粉碎长度合格率为92.4%、果穗损失率为2.06%、籽粒破碎率为0.61%。该机设计各项指标符合国家相关标准,能够满足丘陵山地地区玉米机械化收获需求。

多段移动床干馏炉集气结构的优化研究

为考察移动床干馏炉内部集气结构对串气率的影响,以陕北低阶碎煤为试验对象,搭建移动床冷态试验装置,在不同进气流量下测定各层气量的流量分配比例,研究在不同位置增设集气结构对气体分布的影响。结果表明:气体经布气伞进入移动床后,有10%的气量无法通过集气主伞流出,而从卸料口泄漏导致串气。在布气伞下部0.6 m和1.2 m处、集气主伞上部0.6 m处分别增设一层集气伞,均可以降低串气比例。同时在上部与中部或中部与下部增加两层集气伞时,可以使串气率降低为0。当中部集气伞与主伞内的压差由0 Pa增加至80 Pa时,串气率由2.80%升高至5.22%,设计炉内结构时应考虑降低沿程阻力损失或者加设集气通道。

不同条件下粉碎度及大曲品质研究

制曲原料粉碎后的物料包含大皮、颗粒、细粉三个部分,本实验从钢辊物理特征、使用周期、原料润粮时间等方面探讨其对原料粉碎度影响。实验结果表明,钢辊拉丝角度与深度对物料大皮、颗粒影响较大。随着钢辊使用周期延长,呈现物料大皮偏大、颗粒减少趋势。原料润粮时间以浸润6~9 h为宜。结合季节特性设计粉碎度与水分梯度实验,得出理化指标均衡、感官品质优异的大曲。本实验结果可为中高温制曲生产提供参考。

液压支架立柱防冲吸能构件优化仿真及压溃实验研究

液压支架作为煤炭开采主要支护设备,经常受到冲击地压影响,防冲吸能构件起到保护液压支架作用,为获得更大的初始支反力峰值与吸能量、更小的支反力分散度,对吸能构件参数细化并通过ABAQUS有限元软件进行吸能构件的建模与压溃冲击仿真,获取吸能构件的吸能性能及屈曲变形形态,验证最优尺寸的吸能性能;对比吸能构件平均支反力的预测数据与有限元仿真数据,误差在15%以内,最优尺寸构件的平均支反力模型预测误差为−3.40%,验证吸能构件预测模型所预测数据较为准确;搭建吸能构件压溃实验台,选择5种加载速度,以准静态压溃方式对定制加工的吸能构件进行轴向加载压溃实验,实验结果表明:不同加载速度轴向压溃实验,支反力波动基本一致,最大初始支反力峰值为2253.52 kN,最大支反力标准差为206.23 kN,最小初始支反力峰值为2096.26 kN,最小支反力标准差为189.83 kN,初始支反力峰值的平均值为2149.32 kN,支反力标准差平均值为196.77 kN;不同压溃速度下的轴向压溃实验数据与吸能构件有限元仿真数据对比,初始支反力峰值、支反力标准差的相对误差分别为5.6%、11.07%;对最优尺寸吸能构件通过预测模型法、有限元仿真法、压溃实验法三种方法进行吸能性能分析,预测模型法的平均支反力为1879.7 kN,有限元仿真法的平均支反力为1945.9 kN,压溃实验法平均支反力为1919.8 kN,预测模型误差3.41%,压溃实验误差−1.3%,通过3种方法的数据验证结果,证明了吸能构件分析方法的可靠性和可行性。

不同发酵时期对黑蒜调味粉品质的影响

黑蒜富含微量元素与营养物质,作为一种食品或保健品在市面上流行。黑蒜的品质也引起了人们的广泛关注。普通黑蒜是用新鲜完整的带皮生蒜在高温高湿的发酵箱中自然发酵90~120 d后制成的。然而生蒜是如何在发酵过程中逐渐变黑、黑蒜与生蒜极大的口感差别以及两者营养价值的变化基于什么成为人们疑惑的问题。该研究选取品相完好的紫皮独头蒜,在专业的黑蒜发酵锅中发酵10 d,获得发酵成功的黑蒜,并在发酵过程中对不同发酵时期的黑蒜进行质构测定,经过干燥破碎,制成调味蒜粉,并对其中的还原糖含量、总酸含量、总酚含量、水分含量、粗脂肪含量、蛋白质含量进行测定,由此探寻蒜在发酵过程中产生的变化,从而对不同发酵时期黑蒜调味粉的品质进行综合评价。该研究可拓展关于调味品发酵方面的知识,为提高新型功能性调味粉的营养价值提供更多的数据资源。

麦冬传统炮制工艺与京帮炮制经验探讨

[目的]探讨麦冬的传统炮制工艺和京帮炮制经验,为麦冬的现代研究提供借鉴。[方法]搜集古代本草文献中麦冬炮制的资料及传统京帮传世资料中麦冬炮制的相关记载,并向老药师咨询,在分析整理的基础上对麦冬的各种炮制方法进行复原。[方法]麦冬去心的机制有去心除烦、去心治经枯、去心养肺阴,以第一种流传最广。去心的方法有沸水润去心、清水润去心、焙软去心,以第一种效果最好。酒浸法的目的是减轻麦冬久服胃寒的副作用。米炒法宜将米薄铺于锅中,铺麦冬于米上,不宜翻动,其色均匀,如与米同翻炒则麦冬易鼓起。蒸法有清蒸与拌乳蒸两种。麦冬不易粉碎,《本草纲目》记载的间断焙干法很好。麦冬熬膏与制丸均利用其含汁液的特点。传统京帮麦冬在闷润与去心的方法上均有明显的地方特色,朱麦冬为撒水微润,朱砂细粉随撒随翻动。这两个炮制品种已消失半个世纪。[结论]麦冬的炮制方法的复原和优化,有望提高麦冬药效,为临床提供更高质量的麦冬药材。揭示传统京帮麦冬炮制的地方特色,为复兴消失的炮制品种提供了可能,对于丰富中药资源,提升中药的临床应用价值具有重要意义。

1ZL-7.2型联合整地机的研制

整地作业可将犁耕后的土壤进行碎土、平整,为播种环节创造良好的作业条件,联合整地机在新疆已被广泛应用。近年来大中马力拖拉机保有量逐年增加,为提高整地作业幅宽和效率,研制了一款与大马力拖拉机相配套的联合作业机,开发了新型合金材料的耐磨耙片。作业幅宽为7.2 m,机架可以进行折叠便于运输。田间试验表明,该型机具作业效果良好,故障率低,操作简单、方便。

井下转载破碎点粉尘分布特征及降尘系统研究

为了改善综放工作面转载破碎区域的工作环境,结合粉尘分散度分析和现场实测得出转载机机头前1 m处、破碎机处及前刮板机和后刮板机处是四个主要的产尘位置。其中,转载机机头前1 m处持续不断地产生呼吸性粉尘,其PM5占比高达85.19%,原因在于煤块与带式输送机猛烈撞击后产生大量呼吸性粉尘;破碎机处也产生大量呼吸性粉尘,但积累呼尘的速率相对较慢,其PM10占比可达98%,这些粉尘主要来源于两防护罩间由于连接不吻合而产生的缝隙;前刮板机和后刮板机处可吸入粉尘占比相对稳定且比例较高,粉尘粒度分布相对均匀,这是由于此处煤块普遍较大且携带较高的势能,下落后产生大量微细粉尘。并根据每个产尘点的特性采用不同的喷雾降尘技术并设计相应的降尘系统:转载点喷雾形成全断面喷雾抑尘,破碎机喷雾将粉尘封闭在破碎机内部并沉降,前后刮板机喷雾利用雾群将粉尘完全覆盖。最后通过现场检验,PM5和PM10粉尘的降尘率都达到85%左右,降尘效果良好。

泥石浆型复杂破碎岩体非线性渗流数学模型与实验研究

断层、陷落柱是影响承压水上煤层开采的主要隐患之一,由于其具有碎石块和泥质充填物(泥石浆)构成的复杂结构,其渗透性的确定通常以定性分析为主,缺少量化模型。为了研究泥石浆型复杂破碎岩体渗透性的量化计算方法,开展了渗流实验研究破碎岩体非线性渗流规律,并基于多孔介质分形理论、非线性渗流理论,建立了考虑黏土成分及泥化充填作用的破碎岩体非线性渗流数学模型,最后与实验结果对比验证数学模型的准确性。结果表明:①陷落柱破碎带样品的粒度分布具有一定的分形规律,含有黏土颗粒的破碎带岩体遇水泥化后,分形维数增大,黏土充填封堵了大颗粒岩石碎块内部的大孔隙,降低了破碎岩体的渗透性;②随着破碎带岩体渗透率的降低,非线性开始发生时的临界压力梯度也增大,表明非线性临界压力梯度可以用来量化破碎岩体的阻隔水能力;③非线性开始发生时的临界压力梯度的实验结果与数学模型计算结果吻合,验证了模型的准确性。建立的破碎岩体非线性渗流数学模型首次尝试考虑了黏土成分及泥化充填作用对渗透性的影响,为泥石浆型复杂破碎岩体渗透性的定量计算及水体下、承压水上等特殊开采条件下地质构造的阻隔水性能研究提供了一种新的研究思路。

煤矸石混凝土性能研究现状

煤矸石是在原煤开采过程中产生的一种工业固体废弃物,其堆存量大,利用率相对较低。若将煤矸石用作混凝土骨料,不仅能有效解决煤矸石堆存造成的环境污染,还能缓解天然砂石资源短缺的问题,为煤矸石的大规模利用开辟一条有效途径。该文针对煤矸石作为混凝土骨料的应用特性,系统分析了煤矸石化学成分、矿物组成以及物理特性,概述了国内外关于煤矸石作为骨料对混凝土的工作性能、力学性能、体积稳定性以及耐久性的影响规律,并展望了煤矸石在混凝土骨料应用中的发展趋势,以期为煤矸石在混凝土中的大规模推广利用提供参考。