Microstructural and thermal properties of coal measure sandstone subjected to high temperatures

To study the microscopic structure,thermal and mechanical properties of sandstones under the influence of temperature,coal measure sandstones from Southwest China are adopted as the research object to carry out high-temperature tests at 25℃-1000℃.The microscopic images of sandstone after thermal treatment are obtained by means of polarizing microscopy and scanning electron microscopy(SEM).Based on thermogravimetric(TG)analysis and differential scanning calorimetric(DSC)analysis,the model function of coal measure sandstone is explored through thermal analysis kinetics(TAK)theory,and the kinetic parameters of thermal decomposition and the thermal decomposition reaction rate of rock are studied.Through the uniaxial compression experiments,the stress‒strain curves and strength characteristics of sandstone under the influence of temperature are obtained.The results show that the temperature has a significant effect on the microstructure,mineral composition and mechanical properties of sandstone.In particular,when the temperature exceeds 400℃,the thermal fracture phenomenon of rock is obvious,the activity of activated molecules is significantly enhanced,and the kinetic phenomenon of the thermal decomposition reaction of rock appears rapidly.The mechanical properties of rock are weakened under the influence of rock thermal fracture and mineral thermal decomposition.These research results can provide a reference for the analysis of surrounding rock stability and the control of disasters caused by thermal damage in areas such as underground coal gasification(UCG)channels and rock masses subjected to mine fires.

Recommendations for the diagnosis and treatment of paroxysmal kinesigemc dyskinesia: an expert consensus in China

Paroxysmal dyskinesias are a group of neurological diseases characterized by intermittent episodes of involuntary movements with different causes.Paroxysmal kinesigenic dyskinesia(PKD)is the most common type of paroxysmal dyskinesia and can be divided into primary and secondary types based on the etiology.Clinically,PKD is characterized by recurrent and transient attacks of involuntary movements precipitated by a sudden voluntary action.The major cause of primary PKD is genetic abnormalities,and the inheritance pattern of PKD is mainly autosomal-dominant with incomplete penetrance.The proline-rich transmembrane protein 2(PRRT2)was the first identified causative gene of PKD,accounting for the majority of PKD cases worldwide.An increasing number of studies has revealed the clinical and genetic characteristics,as well as the underlying mechanisms of PKD.By seeking the views of domestic experts,we propose an expert consensus regarding the diagnosis and treatment of PKD to help establish standardized clinical evaluation and therapies for PKD.In this consensus,we review the clinical manifestations,etiology,clinical diagnostic criteria and therapeutic recommendations for PKD,and results of genetic analyses in PKD patients performed in domestic hospitals.

实时震动诱导蛋白扩增检测阳性的散发型克-雅病患者8例的临床特点分析

目的报道8例散发型克-雅病(sCJD)患者的实时震动诱导蛋白扩增(RT-QuIC)检测结果及其临床特点。方法回顾性分析河南省人民医院2018年1月至2021年5月诊断为临床很可能的sCJD, 且送RT-QuIC检测的患者的住院病历。收集患者一般资料(性别、年龄、首发症状、主要临床表现)、辅助检查[头颅磁共振成像(MRI)、脑电图、脑脊液 14-3-3 蛋白、朊蛋白基因、皮肤组织RT-QuIC、自身免疫性脑炎和副肿瘤综合征相关抗体]检查结果, 并对患者进行电话随访, 记录其存活情况。根据脑电图、14-3-3蛋白、病程长短、MRI结果对患者进行分组, 比较组间RT-QuIC结果中荧光达峰时间和荧光峰值的差异。结果入组8例患者, 其中7例患者为亚急性起病, 1例慢性起病。主要的临床症状和体征有进行性认知下降(8/8)、锥体束征(5/8)、走路不稳(4/8)、精神行为异常(4/8)、肌阵挛(4/8)、无动性缄默(4/8)、头晕(3/8)、肢体抖动(2/8)、构音障碍(2/8)、视幻觉(1/8)、视力下降(1/8)。所有患者脑电图检查结果均异常, 其中 5 例可见典型的周期性尖慢复合波(PSWCs)。7例患者头颅MRI弥散加权成像示大脑皮质和(或)基底节的异常高信号, 其中6例累及双侧基底节。8例患者中2例脑脊液14-3-3蛋白阳性;全部患者RT-QuIC检测结果均为阳性;随访结果显示4例患者死亡。RT-QuIC荧光达峰时间在PSWCs阳性组[(7.617±2.164)h]及MRI总评分高组[(7.600±1.907)h]比PSWCs阴性组[(10.602±2.247)h, t=2.84, P=0.010]及MRI总评分低组[(9.760±2.457)h, t=2.26, P=0.032]更短。结论 RT-QuIC检测是早期诊断sCJD的可靠方法。RT-QuIC结果与脑电图出现PSWCs和MRI受累程度可能有关。

Study on in situ stress testing method based on Kaiser effect of acoustic emission and COMSOL simulation

In situ stress testing can improve the safety and efficiency of coal mining.Identifying the Kaiser effect point is vital for in situ stress calculations;however,the in situ stress calculation is limited by the rock sampling angle.Here,the Kaiser effect point identification theory is established and applied to the Xuyong Coal Mine.Uniaxial compression and acoustic emission experiments were carried out on sandstone with 6 sampling directions.Furthermore,COMSOL simulation is applied to study the in situ stress distribution in the coal mine to verify the calculation accuracy.The results are as follows.1)The failure mode of non-bedded and vertical-bedded rocks is primarily tensile shear failure with obvious brittleness in mechanical and acoustic emission characteristics.Shear slip along the bedding plane is the primary failure mode of inclined-bedded rock.Additional take-off points exist in the AE count curve.2)The Kaiser point identification method based on the variation of AE count curve parametersΔti andτi can effectively calculate the in situ stress.According to the numerical value of Kaiser point and sampling direction,the in situ stress of the conveyor roadway in the Xuyong Coal Mine was calculated asσ1=22.81 MPa,σ2=10.87 MPa andσ3=6.14 MPa.3)By the COMSOL simulation study,it was found that a stress concentration zone of 16.13 MPa exists near the two sides roadway.Compared with the Kaiser effect method,the deviation rates of the three-direction principal stress calculated by COMSOL were all less than 5%.This verifies that the in situ stress calculation by Kaiser effect in this study can be applied to the Xuyong Coal Mine.