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.

Investigation of Carbonation of Concrete Based on Crushed Sand and Admixtures

Carbonation is a natural aging process that occurs in all types of concrete. One of its primary implications is the acceleration of steel corrosion caused by the phenomena of depassivation. The goal of this research is to investigate the carbonation of quarry sand-based concrete. The concrete is made of 100% crushed sand 0/6.3, gravel 8/15, and 15/25 from the Arab Contractor quarry in Nomayos, Cameroon, with CEM II B-P 42.5 R from CIMENCAM (Cimenteries du Cameroun). The study employed two admixtures: one with a dual superplasticizing and reducing action (Sikamen) and another with a water-repellent effect (Sika liquid). Carbonation was performed on concrete samples at the following dates: 0, 7, 14, 28, 56, 90, 180 days, one year, and six months. Carbonated concrete (CC) and non-carbonated concrete (NCC) samples are compared in terms of their physical attributes and mineralogical characteristics. The results of this investigation reveal that after more than a year and six months of carbonation, porosity decreases and permeability increases. Despite the high fineness modulus of quarry sand, the compressive strength of quarry sand-based concrete is satisfactory. Carbonation depth is relatively high on some dates, exceeding the minimal cover value for concrete reinforcement. Sikament additive increases concrete compactness and durability while decreasing permeability. Sika water repellant mixes with the lime in cement to generate complimentary crystallizations that block the mortar’s capillaries, making it watertight.

Multi-scale impact crushing characteristics of polymetallic sulphide ores

The effects of crushing energy, ore hardness and particle size of cassiterite polymetallic sulphide ore and lead-zinc polymetallic sulphide ore on the crushing characteristics during impact crushing were investigated by mineral liberation analyzer(MLA) and drop weight test. The results show that both ores contain pyrrhotite, sphalerite, jamesonite, gangue mica and quartz except cassiterite. Cassiterite is closely associated with sulphide and quartz to form aggregates, which are mixed with each other in the form of intergrowth or symbiotic disseminated fine grains. Cassiterite has a significant impact on ore crushing characteristics. Ore hardness is negatively correlated with the product of crushing parameters of A and b, i.e. A×b, the effect of crushing energy on crushing fineness is related to crushing parameters A and b, and the influence degree increases with the increase of A. The influence degree increases with the increase of b when crushing energy ECS is less than 1 kW·h/t, and the influence degree decreases with the increase of b when crushing energy ECS is greater than 1 kW·h/t. The impact of crushing energy on crushing fineness is greater than that of ore particle size when the crushing energy is lower;on the contrary, the impact of ore particle size on crushing fineness is greater than that of crushing energy when crushing energy is higher.

New testing methodology for the quantification of rock crushability:Compressive crushing value(CCV)

Crushing is a size reduction process that plays a key role in both mineral processing and crushing–screening plant design. Investigations on rock crushability have become an important issue in mining operations and the manufacture of industrial crusher equipment. The main objective of this research is to quantify the crushability of hard rocks based on their mineralogical and mechanical properties. For this purpose, the mineralogical, physical, and mechanical properties of various hard rocks were determined. A new compressive crushing value(CCV) testing methodology was proposed. The results obtained from CCV tests were compared with those from mineralogical inspections, rock strength as well as mechanical aggregate tests. Strong correlations were found between CCV and several rock and aggregate properties such as uniaxial compressive strength(UCS), the brittleness index(S_(20)), and aggregate impact value(AIV). Furthermore, the relationship between the mineralogical properties of the rocks and their CCVs were established. It is concluded that the proposed testing methodology is simple and highly repeatable and could be utilized as a pre-design tool in the design stage of the crushing process for rock quarries.

冠状动脉分叉病变介入治疗DK Crush技术与经典Crush技术疗效比较

目的 探讨DK Crush技术与经典Crush技术治疗冠状动脉分叉病变的临床价值。方法 选择该院2019年6月—2020年6月收治的冠状动脉分叉病变患者66例为研究对象,随机数表法均分为研究组和对照组,各33例。研究组行DK Crush技术治疗,对照组行经典Crush技术治疗。比较两组治疗效果。结果 研究组手术中造影剂总量少于对照组,PCI耗时高于对照组,球囊数量少于对照组,FKBI优于对照组,差异有统计学意义(t=6.166、7.385、10.667,χ^(2)=16.189,P<0.05)。对照组手术后5例发生急性心肌梗死,4例再次行PCI手术,与研究组比较,差异无统计学意义(χ^(2)=3.462、2.395,P>0.05)。手术后,研究组主支血管各指标与对照组比较,均差异无统计学意义(t=0.426、0.135、0.994、0.401,P>0.05);研究组分支血管中除最终对吻扩张失败率外,其余指标与对照组比较差异有统计学意义(t=6.058、3.922、4.585、4.927,P<0.05);手术后12个月,两组主支血管中各指标差异无统计学意义(t=1.999、0.280、1.020、0.088,χ^(2)=0.515,P>0.05);研究组分支血管中最小管腔直径大于对照组,直径狭窄度低于对照组,差异有统计学意义(t=6.288、23.418,P<0.05)。结论 改良后的DK Crush技术可有效提高对吻扩张的成功率,且手术后并发症少,安全性高,值得临床推广应用。

Mathematical modeling on multi-stage series crushing ratio distribu- tion based on fuzzy physical programming

Double-layer, multi-roller plate crusher is a new device, that uses a multi-stage series crushing style to break particles, with the crushing ratio distribution directly influencing the machine＇s performance. Three crushing ratios of 2.25, 2.15 and 2.01, used for fuzzy physical programming, were determined. The comparison of the optimized result between the double-layer multi-roller plate crusher and a high pressure roll grinder showed that the double-layer multi-roller plate crusher had a better performance, reducing crushing force and wear.

改良Y支架术与reverse crush支架术治疗冠状动脉分叉病变的疗效比较

目的对比改良Y支架术与reverse crush支架术治疗冠状动脉分叉病变的临床疗效。方法将65例冠状动脉分叉病变患者随机分为两组,分别行改良Y支架术(改良组)和reverse crush支架术(对照组)治疗,观察两组疗效和随访1年主要心脏不良事件发生率。结果改良组手术时间、X线曝光时间短于对照组(P均<0.01);造影剂和球囊用量少于对照组(P均<0.01),最终球囊对吻成功率更高,但无统计学差异(P>0.05);6～9个月造影随访,改良组分支血管再狭窄率低于对照组(P<0.01)。1年随访结束,对照组心脏不良事件发生率高于改良组,但无统计学差异(P>0.05)。结论改良Y支架术较reverse crush支架术操作简单、费时少,具有更低的分支再狭窄率,有减少随访1年临床心脏不良事件的趋势,推荐临床优先选用。

应用Partner支架完成Crush技术治疗冠脉分叉病变的即刻及近期随访结果

目的评价国产西罗莫司药物洗脱支架（Partner）完成Crush技术治疗冠状动脉分叉病变的安全性及有效性。方法冠状动脉造影证实为冠状动脉真性分叉病变（Medina分型为1．1．1），主支和分支均选择Partner支架完成Crush技术，术后6月进行冠状动脉造影随访。结果共30例患者入选，冠脉分叉病变31处。患者平均年龄（61．7±11．2）岁，其中男性占66．7％。31处分叉病变分布：前降支与对角支51．6％，左主干与前降支和回旋支32．3％，右冠脉左室后侧支与后降支9．7％，回旋支与钝缘支6．5％。非顺应性球囊高压扩张占58．1％，最后完成球囊对吻技术96．8％。主支和分支置人支架（1．50±0．55）枚和（1．10±0．34）枚，支架长度为（37．2±1．2）mm和（21．6±0．83）mm，支架直径为（3．27±0．51）mm和（2．76±0．48）mm。近期随访主要心血管事件（MACE）的发生率为3.3％。结论西罗莫司洗脱支架Partner完成Crush技术治疗冠脉分叉病变是安全、有效的，而且相对低的医疗费用使国产西罗莫司洗脱支架Partner在复杂病变中的应用更具有吸引力。

改良T型支架置入术与经典crush技术治疗冠状动脉分叉病变的比较研究

目的评估改良T型支架置入术与经典crush技术治疗真性冠状动脉分叉病变的安全性及有效性。方法自2008年12月至2010年1月共入选62例真性冠状动脉分叉病变患者(分支血管直径≥2.5mm),其中34例患者行经典crush治疗,28例患者行改良T型支架置入术,比较两组患者术后即刻成功率、住院期间及术后30d内的主要不良心脏事件、术后6个月支架再狭窄率。结果与经典crush组相比,改良T型支架治疗组术后分支最小管腔直径大〔(2.72±0.22)mmvs(2.39±0.30)mm,P<0.01〕,分支残余狭窄程度小〔(8.3±6.8)%vs(18.6±10.2)%,P<0.01〕,最终球囊对吻扩张成功率高(100%vs73.5%,P<0.01),支架内再狭窄率较低(5.0%vs32.0%)。两组患者术后即刻成功率无统计学差异(88.24%vs100%,P=0.12)。经典crush组有1例患者因亚急性血栓再次行PCI治疗。结论改良T型支架置入术治疗冠状动脉分叉病变是安全的,其远期有效性优于经典crush技术。

Simvastatin对大鼠坐骨神经crush损伤修复作用研究

目的探讨他汀类(statins)药物Simvastatin在大鼠坐骨神经损伤修复中的作用及可能的作用机制。方法制作SD大鼠标准坐骨神经钳夹损伤(crush)模型后,分别予Simvastatin和溶媒对照干预2周。手术前后不同时间点进行趾展功能指数测定、神经电生理学、血脂水平、血清IL-6检测和组织学评价。结果Simvastatin干预组与对照组比较,趾展功能指数在术后5d和8d显著增大(P<0.05),足趾展开速度快;2周肌肉复合动作电位幅度高,4周神经传导速度快;组织学显示有髓神经纤维数量多,髓鞘厚,排列相对整齐。各组手术前血脂水平无差异,手术后2周均有不同程度的降低,但Simvastatin干预组总胆固醇降低程度最轻,与对照组比较有显著差异(P<0.05);Simvastatin干预组手术后5d,血清IL-6水平明显低于对照组(P<0.05)。结论本研究发现,Simvastatin可能通过抑制免疫炎症反应,维持神经损伤后胆固醇的平衡,促进大鼠坐骨神经损伤的修复和再生。

血管内超声指导下改良CRUSH技术治疗左主干分叉病变的效果及安全性

目的分析血管内超声(IVUS)指导下改良CRUSH技术对左主干分叉病变的疗效及随访结果。方法回顾性分析2012年7月至2014年6月经冠状动脉造影术(CAG)确诊为左主干分叉病变患者的临床资料,共6例,均在IVUS指导下接受改良CRUSH技术治疗。治疗前后均行IVUS检查,记录术前左主干、前降支及回旋支病变最小管腔面积(MLA)、最小管腔直径(MLD)、斑块负荷(PB)及其术后即刻影像表现,观察患者住院期间及出院后主要心脏不良事件(MACE,包括死亡、非致死性心肌梗死及靶病变重建)及支架内血栓、支架内再狭窄情况。结果6例患者中,应用Reverse Crush技术1例、Step Crush技术2例、DK Crush技术3例,植入药物洗脱支架共12枚,手术成功率为100%(6/6);术后临床症状均显著缓解,未见严重并发症发生。IVUS提示,6例患者术前左主干MLA为(4.57±1.36)mm2,MLD为(2.28±0.48)mm;左前降支开口MLA为(3.89±1.66)mm2,PB为(67.20±11.87)%;左回旋支开口MLA为(4.87±0.51)mm2,PB为(64.26±5.15)%;IVUS检查左前降支MLD高于QCA检查结果(P<0.05)。随访2年,未出现MACE及支架血栓情况。结论IVUS指导下左主干分叉病变改良CRUSH技术治疗左主干分叉病变效果明显,手术成功率高,具有很好的安全性和临床中远期疗效。

改良mini-Crush技术治疗冠状动脉分叉病变

冠状动脉病变中分叉病变较为常见，约占经皮冠状动脉介入治疗（percutaneous coronary intervention，PCI）的15％-20％。由于存在斑块移位、病变弹性回缩及支架内再狭窄，冠状动脉分叉病变的介入治疗存在许多难题。经典挤压（Crush）支架技术支架可完全覆盖分支开口，但是与其他技术相比，Crush支架术支架内血栓发生率似乎有增加的趋势。

改良mini-Crush支架术治疗冠状动脉分叉病变的疗效观察

目的探讨改良mini-Crush(MMC)支架术治疗冠状动脉左前降支分叉病变患者的可行性及12个月的疗效。方法连续入选2006年2月至2014年5月沈阳军区总医院住院并行经皮冠状动脉介入治疗(PCI)患者,共纳入311例,其中169例接受MMC支架术治疗(MMC组),142例接受裙裤(Culotte)支架术治疗(Culotte组)。观察入选患者的临床基本特征、手术操作特征及12个月的随访结果。结果两组患者的主支及分支均成功置入支架。MMC组患者的主支及分支血管病变狭窄程度均明显高于Culotte组[(83.60±10.11)%比(79.20±8.80)%,(77.60±14.03)%比(72.60±9.42)%,均P<0.001],术中使用指引导丝及球囊的数量均明显少于Culotte组[2(2,3)根比3(2,3)根,3(3,3)枚比3(3,4)枚,均P<0.001],最终球囊对吻后扩张成功率明显高于Culotte组[165例(97.6%)比130例(91.5%),P=0.023]。两组患者住院期间和随访期间的主要不良心脏事件和支架内血栓的发生率分别比较,差异均无统计学意义(均P>0.05)。与Culotte组患者相比,MMC组患者分支口部再狭窄的发生率有降低的趋势[4例(2.4%)比9例(6.3%),P=0.081]。结论在治疗冠状动脉分叉病变时,MMC支架术操作更为简化,明显缩短手术时间,可作为冠状动脉真性分叉病变的治疗策略之一。

前送球囊DK-Crush技术治疗真性冠状动脉分叉病变:与经典DK-Crush技术对比

目的探讨改良DK-Crush技术(即前送球囊DK-Crush技术)处理冠状动脉真性分叉病变的有效性和安全性。方法本研究连续入选2007年1月至2011年12月在本院住院,冠状动脉造影证实为真性分叉病变(分支血管直径≥2.0 mm)的患者共196例。随机分为两组,每组各98例,其中一组接受经典DK-Crush技术治疗,另外一组接受前送球囊DK-Crush技术治疗。比较两组患者临床特征、病变分布、曝光时间、手术时间、使用球囊数量、造影剂用量、手术相关费用、手术成功率,并记录出院后6个月临床随访时的主要心血管事件(MACE)发生率。结果两组患者基础临床特征差异无显著性,两组患者分叉病变分布差异无显著性。用前送球囊DK-Crush组与经典DK-Crush组患者的主干与分支血管之间的夹角[(54±18)°︰(49±15)°,P=0.10]、主支血管病变长度[(22.5±7.1)mm︰(24.6±7.3)mm,P=0.10]、手术成功率(98%±1%︰99%±1%,P=0.33)、术后即刻分支血管开口部位最小血管直径[(2.72±0.29)mm∶(2.76±0.23)mm,P=0.10]、残余狭窄率(6.8%±2.2%︰6.5%±2.6%,P=0.10)差异均无显著性。前送球囊DK-Crush组与经典DKCrush组比较,患者曝光时间短[(38±11)min∶(50±13)min,P=0.03]、手术时间短[(65±17)min︰(78±18)min,P=0.03]、使用球囊数量少[(1.7±0.4)个︰(2.6±0.7)个,P=0.02]、造影剂使用量小[(68±25)ml︰(83±24)ml,P=0.03]、手术相关费低[(45 120±234)元︰(50284±245)元,P=0.03]。6个月随访时前送球囊DK-Crush组患者的MACE事件发生率(5.7%±2.2%︰5.3%±1.6%,P=0.08)、造影再狭窄率(7.8%±2.6%︰7.5%±2.2%,P=0.10)差异均无显著性。结论改良的DK-Crush技术能显著缩短曝光时间、减少球囊数量,减少患者的手术费用,其6个月随访结果证实了其在有效性及安全性方面均与经典DK-Crush技术相当。

血管内超声联合冠状动脉造影指导改良CRUSH在左主干病变中的应用效果观察

目的探讨左主干病变患者应用冠状动脉造影(CAG)与血管内超声(IVUS)联合指导下改良冠状动脉旁路移植术(CRUSH)的临床效果。方法临床选择2016年2月-2019年5月在焦作市人民医院接受诊治的行改良CRUSH左主干病变患者60例,根据随机对照原则分组,分为对照组(n=30)和观察组(n=30),观察组在冠状动脉造影和血管内超声指导下完成,对照组在血管内超声指导下完成,比较两组病变长度、血管直径、右冠状动脉狭窄、回旋支狭窄、前降支狭窄参数指标;比较两组的面积狭窄率、最小管腔面积、最小管腔直径、支架长度、支架直径等指标;比较两组的支架内血栓形成、心肌梗死、全因死亡发生情况。结果两组的病变长度、血管直径、右冠状动脉狭窄、回旋支狭窄、前降支狭窄参数指标差异无统计学意义(P> 0.05);观察组的面积狭窄率显著低于对照组,差异有统计学意义(P <0.05);观察组的最小管腔面积、最小管腔直径、支架长度、支架直径等指标显著高于对照组,差异有统计学意义(P <0.05);两组发生支架内血栓形成、心肌梗死、全因死亡等情况比较,差异无统计学意义(P> 0.05)。结论对于较单一的左主干病变应用冠状动脉造影与血管内超声联合指导下行改良CRUSH的诊断价值更高,值得临床应用。

Influence of some rock strength properties on jaw crusher performance in granite quarry

The influence of rock strength properties on Jaw Crusher performance was carried out to determine the effect of rock strength on crushing time and grain size distribution of the rocks.Investigation was conducted on four different rock samples namely marble,dolomite,limestone and granite which were representatively selected from fragmented lumps in quarries.Unconfined compressive strength and Point load tests were carried out on each rock sample as well as crushing time and size analysis.The results of the strength parameters of each sample were correlated with the crushing time and the grain size distribution of the rock types.The results of the strength tests show that granite has the highest mean value of 101.67 MPa for Unconfined Compressive Strength(UCS) test,6.43 MPa for Point Load test while dolomite has the least mean value of 30.56 MPa for UCS test and 0.95 MPa for Point Load test.According to the International Society for Rock Mechanic(ISRM) standard,the granite rock sample may be classified as having very high strength and dolomite rock sample,low strength.Also,the granite rock has the highest crushing time(21.0 s) and dolomite rock has the least value(5.0 s).Based on the results of the investigation,it was found out that there is a great influence of strength properties on crushing time of rock types.

A New Rapid and Batch-oriented Crushing Method for DNA Extraction from Maize Leaves

The crushing of leaves is the most time and effort-consuming part in DNA extraction which is a fundamental step in the study of molecular biology. In this study, a new rapid and batch-oriented crushing method for DNA extraction from maize leaves was developed. In addition, the practicability of the developed method in molecular marker-assisted breeding was verified using SSR molecular maker technology so as to provide a rapid, batch-oriented, low-cost and non-toxic leafcrushing method for a large number of molecular marker tests, improving test efficiency.

Crush技术对于前三叉病变在基层医院的应用体会

目的评估Crush技术对于前三叉病变在基层医院应用的可行性及技术难点。方法选择冠脉造影显示真性分叉病变患者,应用Crush技术在主支和分支分别置入药物涂层(Endeavor)支架,并行对吻球囊扩张术。观察体会术前、术中及术后的注意事项。结果2例即刻手术成功100%,均成功行对吻球囊扩张术。结果2例均未发生急性及亚急性血栓形成,急性心肌梗死、心律失常等并发症。结论Crush技术对于前三叉病变在基层医院的应用是可行的,并且能够获得成功。