Quantitative models for microstructure and thermal conductivity of vermicular graphite cast iron cylinder block based on cooling rate

The relationships of cooling rate with microstructure and thermal conductivity of vermicular graphite cast iron(VGI) cylinder block were studied, which are important for design and optimization of the casting process of VGI cylinder blocks. Cooling rates at different positions in the cylinder block were calculated based on the cooling curves recorded with a solidification simulation software. The metallographic structure and thermal conductivity were observed and measured using optical microscopy(OM), scanning electrical microscopy(SEM) and laser flash diffusivity apparatus, respectively. The effects of the cooling rate on the vermicularity, total and average areas of all graphite particles, and the pearlite fraction in the VGI cylinder block were investigated. It is found that the vermicularity changes in parabola trend with the increase of cooling rate. The total area of graphite particles and the cooling rate at eutectoid stage can be used to predict pearlite fraction well. Moreover, it is found that the thermal conductivity at room temperature is determined by the average area of graphite particles and pearlite fraction when the range of vermicularity is from 80% to 93%. Finally, the quantitative models are established to calculate the vermicularity, pearlite fraction, and thermal conductivity of the VGI cylinder block.

A rare case of Staphylococcus lugdunensis septicemia associated with myocarditis and atrioventricular block

Myocarditis is a relatively rare,possibly life-threatening disease characterized by the inflammation of the myocardium.111 The disease pathogenesis is primarily initiated by acute injury and necrosis of cardiomyocytes,leading to an inflammatory response mediated by the immune system that can potentially cause further aggravation of myocardial damage and organ dysfunction.Prognosis in patients with myocarditis depends on the clinical presentation,which ranges from an asymptomatic disease course to the concomitant development of cardiac arrhythmias,heart failure,cardiogenic shock and even the occurrence of death in extreme cases[1].

The productivity evaluation model and its application for finite conductivity horizontal wells in fault block reservoirs

It is very difficult to evaluate the productivity of horizontal wells in fault block reservoirs due to the influence of fault sealing.On the basis of the method of images and source-sink theory,a semianalytical model coupling reservoir and finite conductivity horizontal wellbore flow dynamics was built,in which the influence of fault sealing was taken into account.The distribution of wellbore flow and radial inflow profiles along the horizontal interval were also obtained.The impact of the distance between the horizontal well and the fault on the well productivity was quantitatively analyzed.Based on this analysis,the optimal distance between the horizontal well and the fault in banded fault block reservoirs could be determined.According to the field application,the relative error calculated by the model proposed in this paper is within ±15%.It is an effective evaluation method for the productivity of horizontal wells in fault block reservoirs.The productivity of the horizontal well increases logarithmically as the distance between the horizontal well and the fault increases.The optimal distance between the horizontal well and the fault is 0.25-0.3 times the horizontal well length.

Nickel-catalyzed Construction of Heat Conductive Network in Electrically Calcined Anthracite (ECA) Based Carbon Blocks

Nickel nitrate was introduced into carbon blocks by using ECA aggregates as catalyst-carrier.The Ni-containing anthracite aggregates were firstly prepared by mixing anthracite aggregates in nickel nitrate ethanol solution and then incorporated into carbon blocks after pre-treating.The phase composition,microstructure and properties of all carbon blocks fired at 1 000℃or 1 400℃in a coke bed were studied with the aid of an X-ray diffractomer,a field emission scanning electron microscope,a mercury porosimetry and a laser thermal conductivity meter.The results showed that the addition of Ni-containing anthracite aggregates promoted the formation of one-dimensional nanocarbon andβ-SiC whiskers at 1 000℃and the growth ofβ-Sialon at 1 400℃,respectively.Moreover,the cold compressive strength and microporosity characteristics of the carbon blocks with the addition of Ni-containing anthracite aggregates were enhanced and the thermal conductivity was remarkably improved attributing to the high heat conductive network formed by the ceramic phases.

Control of Microdomain Orientation in Block Copolymer Thin Films by Electric Field for Proton Exchange Membrane

Owing to the recent push toward efficient energy storage/conversion devices, fuel cells have become a strong candidate for energy conversion equipments. On the other hand, block copolymer polyelectrolytes are interesting materials for proton exchange membranes in fuel cells. Thus a considerable attention has been paid to the development of block copolymer polyelectrolyte membranes. In this study, the microdomains in block copolymer polyelectrolytes were controlled by external electric fields to develop high performance membranes with improved proton conductivity. The microdomain alignments in sulfonated polystyrene-b-hydrogenated poly butadiene-b-polystyrene block copolymer electrolyte were monitored by cross-sectional transmission electron microscopy analysis. The proton conductivities of the block copolymer electrolyte membranes were measured before and after exposure to electric field. In addition, the morphological features of the block copolymer electrolyte were observed with small angle x-ray scattering and atomic force microscopy.

Study on characteristics of a double-conductible channel organic thin-film transistor with an ultra-thin hole-blocking layer

The properties of top-contact organic thin-film transistors （TC-OTFTs） using ultra-thin 2, 9-dimethyl-4, 7- diphenyl-1, 10-phenanthroline （BCP） as a hole-blocking interlayer have been improved significantly and a BCP interlayer was inserted into the middle of the pentacene active layer. This paper obtains a fire-new transport mode of an OTFT device with double-conductible channels. The accumulation and transfer of the hole carriers arc limited by the BCP interlayer in the vertical region of the channel. A huge amount of carriers is located not only at the interface between pentacene and the gate insulator, but also at the two interfaces of pentacene/BCP interlayer and pentacene/gate insulator, respectively. The results suggest that the BCP interlayer may be useful to adjust the hole accumulation and transfer, and can increase the hole mobility and output current of OTFTs. The TC-OTFTs with a BCP interlayer at VDS = --20 V showed excellent hole mobility μFE and threshold voltage VTH of 0.58 cm^2/（V-s） and -4.6 V, respectively.

Expression of mRNA-encoding subunits of N-methyl-D-aspartate receptor in the hypothalamus in sustained monaural block of auditory air-conduction model rats

A sustained monaural block of auditory air-conduction model was established in rats through subcutaneous suture in the right ear canal.The gene expression levels of hypothalamic N-methyl-D-aspartate receptor NR1,NR2A,NR2B and NR2C mRNA in the auditory central nervous system of Sprague-Dawley rats at postnatal 9,23,37 days were determined after an environmental change.Reverse transcription-PCR assay showed that the critical period for the development of NR1,NR2A,and NR2B subunits in the left hypothalamus and NR1-and NR2B-dependent auditory neurons in the right hypothalamus terminated 23 days after the suture in the right ear.The critical period for the development of NR2A subunit-dependent auditory neurons in the right hypothalamus was terminated by postnatal day 37.The results confirmed that N-methyl-D-aspartate receptor subunits in the hypothalamus may be regulated by the auditory environment.

Cystic fibrosis transmembrane conductance regulator chloride channel blockers:Pharmacological,biophysical and physiological relevance

Dysfunction of the cystic fibrosis transmembrane con-ductance regulator(CFTR) chloride channel causes cys-tic fibrosis, while inappropriate activity of this channeloccurs in secretory diarrhea and polycystic kidney dis-ease. Drugs that interact directly with CFTR are there-fore of interest in the treatment of a number of diseasestates. This review focuses on one class of small mol-ecules that interacts directly with CFTR, namely inhibi-tors that act by directly blocking chloride movementthrough the open channel pore. In theory such com-pounds could be of use in the treatment of diarrheaand polycystic kidney disease, however in practice allknown substances acting by this mechanism to inhibitCFTR function lack either the potency or specificity forin vivo use. Nevertheless, this theoretical pharmaco-logical usefulness set the scene for the developmentof more potent, specific CFTR inhibitors. Biophysically,open channel blockers have proven most useful as ex-perimental probes of the structure and function of theCFTR chloride channel pore. Most importantly, the useof these blockers has been fundamental in developing afunctional model of the pore that includes a wide innervestibule that uses positively charged amino acid sidechains to attract both permeant and blocking anionsfrom the cell cytoplasm. CFTR channels are also subjectto this kind of blocking action by endogenous anionspresent in the cell cytoplasm, and recently this blocking effect has been suggested to play a role in the physio-logical control of CFTR channel function, in particular as a novel mechanism linking CFTR function dynamically to the composition of epithelial cell secretions. It has also been suggested that future drugs could target this same pathway as a way of pharmacologically increasing CFTR activity in cystic fibrosis. Studying open channel blockers and their mechanisms of action has resulted in significant advances in our understanding of CFTR as a pharmacological target in disease states, of CFTR chan-nel structure and function, and of how CFTR activity is controlled by its local environment.

Defective recovery of QT dispersion following transcatheter aortic valve implantation： frequency, predictors and prognosis

Background Corrected QT dispersion （cQTD） has been correlated with non-uniform ventricular repolarisation and increased mortality. In patients with aortic stenosis, cQTD has been shown improved after surgical valve replacement, but the effects of transcatheter aortic valve implantation （TAVI） are unknown. Therefore, we sought to explore the frequency, predictors and prognostic effects of defective cQTD recovery at 6 months after TAVI. Methods A total of 222 patients underwent TAVI with the Medtronic-CoreValve System between November 2005 and January 2012. Patients who were on class Ⅰ or Ⅲ antiarrhythmics or on chronic haemodialysis or who developed atrial fibrillation, a new bundle branch block or became pacemaker dependent after TAVI were excluded. As a result, pre-, post- and follow-up ECG （median： 6 months） analysis was available in 45 eligible patients. Defective cQTD recovery was defined as any progression beyond the baseline cQTD at 6 months. Results In the 45 patients, the mean cQTD was 47 ± 23 ms at baseline, 45 ±17 ms immediately after TAVI and 40 ± 16 ms at 6 months （15% reduction, P = 0.049）. Compared to baseline, cQTD at 6 months was improved in 60% of the patients whereas defective cQTD recovery was present in 40%. cQTD increase immediately after TAVI was an independent predictor of defective cQTD recovery at 6 months （per 10 ms increase; OR： 1.89, 95% CI： 1.15-3.12）. By univariable analysis, defective cQTD recovery was associated with late mortality （HR： 1.52, 95% CI： 1.05-2.17）. Conclusions Despite a gradual reduction ofcQTD after TAVI, 40% of the patients had defective recovery at 6 months which was associated with late mortality. More detailed ECG analysis after TAVI may help to avoid late death.

High Degree Atrioventricular Block Complicated Cardiac Sarcoidosis: Case Report

Cardiac Sarcoidosis (CS) is a rare and deceptive disease affecting young adults with catastrophic results including life threatening arrhythmia, congestive heart failure and even sudden death as the initial presentation. CS has been linked to a significant high morbidity & mortality. We present two patients: The first patient with an initial cardiac event that led us to a diagnosis of Pulmonary and Cardiac Sarcoidosis. A second patient, who was diagnosed initially with pulmonary Sarcoidosis, presented with a severe heart conduction abnormality. Both patients were successfully treated with permanent pacemakers. The dual purpose of our study is first to emphasize the importance of follow up on patients with Non-Cardiac Sarcoidosis for cardiac involvement and secondly to increase awareness of CS as part of a differential diagnosis among young adults with unexplained arrhythmia.

THE RESULTS OF HEART RHYTHM DISTURBANDCES TREATMENT USING SELENIUM

Selenium concentration in patients with heart rhythm disturbances and the part ofselenium in treatment of this pathology were studied.50 patients(age 16-67)were studied.The check group consisted of 23 healthypatients(age 21-44).Selenium concentration in patients’ blood was measured.Thencorrection of selenium concentration was done.With the daily dose of 450mkg,selenium concentration in blood was managed to increase up to 60-70%.In compaison with the check group selenium decrease up to 43 and 78.4mkg(standard 90-120mkg/l)was discovered.The most marked decrease of seleniumconcentration was noticed in patients with idiopathic transverse blocks 34.4mkg/land paroxysmal supraventricular tachycardias(SVT)not caused by ischemic heartdisease(ICHD)-39.5mkg/l.Thee patients with ICHD(tachy-and bradycardia)hadthe selenium decrease up to 55.8mkg/l.After selenium therapy during 2 weeks thefollowing results were obtained:in cases of SVT the beneficial result was reached in75%;in cases of the tachycardias caused by ICHD-25%.In cases of idiopathictraverse blocks the heart conduction restoring after selenium recovery was noticedin half of patients.In case this pathology is caused by ICHD no beneficial effect wasnoticed.

Sulfonated fluorinated multi-block copolymer hybrid containing sulfonated(poly ether ether ketone) and graphene oxide: A ternary hybrid membrane architecture for electrolyte applications in proton exchange membrane fuel cells

A ternary hybrid membrane architecture consisting of sulfonated fluorinated multi-block copolymer （SFMC）, sulfonated （poly ether ether ketone） （SPEEK） and I or 5 wt% graphene oxide （GO） was fabricated through a facile solution casting approach. The simple, but effective monomer sulfonation was performed for SFMC to create compact and rigid hydrophobic backbone structures, while conventional random sulfonation was carried-out for SPEEK. Hydrophilic-hydrophobic-hydrophilic structure of SFMC enhances the compatibility with SPEEK and GO and allows for an unprecedented approach to alter me- chanical strength and proton conductivity of ternary hybrid membrane, as verified from universal test machine （UTM） curves and alternating current （AC） impedance plots. The impact of GO integration on the morphology and roughness of hybrid membrane was scrutinized using field emission scanning electron microscope （FE-SEM） and atomic force microscope （AFM）. Ternary hybrid showed uniform intercalation of GO nanosheets throughout the entire surface of membrane with an increased surface roughness of 8.91 nm. The constructed ternary hybrid membrane revealed excellent water absorption, ion exchange capacity and gas barrier properties, while retaining reasonable dimensional stability. The well-optimized ternary hybrid membrane containing 5 wt% GO revealed a maximum proton conductivity of 111.9 mS/cm, which is higher by a factor of two-fold with respect to that of bare SFMC membrane. The maximum PEMFC power density of 528.07mW/cm2 was yielded by ternary hybrid membrane at a load current density of 1321.1 mA/cm2 when operating the cell at 70 ℃ under 100% relative humidity （RH）. In comparison, a maximum power density of only 182.06 mW/cm2 was exhibited by the bare SFMC membrane at a load current density of 455.56 mA/cm2 under same operating conditions.

A highly reduced Mo_(74) polyoxometalate featuring high proton conductivity accessed by building block strategy

Highly reduced polyoxometalates(POMs) are predicted to be used as rather high energy density materials;however,it still suffers from the limited cluster species and reduction ratio.Here we demonstrate that it is possible to employ the building block strategy to generate a highly reduced polyoxomolybdate(C_(2)H_(8)N)_(14)(NH_(4))_(4)H_(14)[Mo_(48)-ⅤMo_(26)ⅥO_(202)(OH)_(12)(SO_(4))_(6)]·46H_(2)O(Mo_(74)).The fundamental Mo-based{Mo_x}(x=4,5,and 6) building blocks,which are templated by tetra-coordinated anions{MoO_(4)}or{SO_(4)},not only lay foundation for the formation of Mo_(74) featuring an unprecedented reduction ratio of 65%,but also give rise to SBBs-mediated(secondary building blocks) supramolecular dense packing interactions among the isolated Mo_(74) clusters that are favorable for proton conduction.Remarkably,high proton conductivity(2.04×10^(-2)S cm^(-1)) had been realized at 50℃ and 90% relative humidity,revealing one of the well-known POMs-based crystalline proton conducting materials.This result highlights that this building block approach possesses great potential in producing highly reduced POM systems that can achieve controllable reduced ratio and desirable properties.

Left bundle branch pacing set to outshine biventricular pacing for cardiac resynchronization therapy?

The deleterious effects of long-term right ventricular pacing necessitated the search for alternative pacing sites which could prevent or alleviate pacinginduced cardiomyopathy.Until recently,biventricular pacing(BiVP)was the only modality which could mitigate or prevent pacing induced dysfunction.Further,BiVP could resynchronize the baseline electromechanical dssynchrony in heart failure and improve outcomes.However,the high non-response rate of around 20%-30%remains a major limitation.This non-response has been largely attributable to the direct non-physiological stimulation of the left ventricular myocardium bypassing the conduction system.To overcome this limitation,the concept of conduction system pacing(CSP)came up.Despite initial success of the first CSP via His bundle pacing(HBP),certain drawbacks including lead instability and dislodgements,steep learning curve and rapid battery depletion on many occasions prevented its widespread use for cardiac resynchronization therapy(CRT).Subsequently,CSP via left bundle branch-area pacing(LBBP)was developed in 2018,which over the last few years has shown efficacy comparable to BiVP-CRT in small observational studies.Further,its safety has also been well established and is largely free of the pitfalls of the HBP-CRT.In the recent metanalysis by Yasmin et al,comprising of 6 studies with 389 participants,LBBPCRT was superior to BiVP-CRT in terms of QRS duration,left ventricular ejection fraction,cardiac chamber dimensions,lead thresholds,and functional status amongst heart failure patients with left bundle branch block.However,there are important limitations of the study including the small overall numbers,inclusion of only a single small randomized controlled trial(RCT)and a small follow-up duration.Further,the entire study population analyzed was from China which makes generalizability a concern.Despite the concerns,the meta-analysis adds to the growing body of evidence demonstrating the efficacy of LBBP-CRT.At this stage,one must acknowledge that the fact that still our opinions on this technique are largely based on observational data and there is a dire need for larger RCTs to ascertain the position of LBBPCRT in management of heart failure patients with left bundle branch block.

具有可控空穴抽取路径的低损耗4H-SiC双沟槽超结IGBT

基于TCAD设计并仿真了一种具有可控空穴抽取(CHE)路径的双沟槽超结IGBT(CHE-SJ-TIGBT)结构。该器件采用肖特基和非对称超结结构,以增强器件的导通性能和阻断能力。CHE路径由金属栅极(MES)控制。CHE-SJ-TIGBT导通时,高偏置的MES栅极电压会夹断CHE路径,使P-屏蔽层(P-shield)处于浮空状态,以维持较高电导调制并获得较低的导通压降(V_(on))。CHE-SJ-TIGBT关断过程中,CHE路径开启,提供额外的空穴抽取路径,有利于降低关断损耗(Eoff)。仿真结果表明,与浮空的P-shield IGBT(FS-TIGBT)和接地的P-shield IGBT(GSTIGBT)相比,CHE-SJ-TIGBT的V_(on)分别降低了58.02%和68.64%,同时短路耐受时间分别提升了55.8%和32.8%。此外,阻断电压提升了约18.6%。CHE-SJ-TIGBT的关断损耗虽略高于GS-TIGBT,但比FS-TIGBT低了70%,在V_(on)与Eoff之间存在更好的折中关系。

竖脊肌平面阻滞治疗竖脊肌肌筋膜疼痛综合征的效果

目的探讨超声引导下竖脊肌平面阻滞治疗竖脊肌肌筋膜疼痛综合征的疗效。方法选择2021年6月至2023年6月期间在医院治疗的60例竖脊肌肌筋膜疼痛综合征患者,随机分为传统痛点阻滞组(F组)和筋膜平面阻滞组(FB组),每组30例,比较两组治疗后视觉模拟评分法(visual analogue scale,VAS)和疼痛缓解有效率。结果两组患者的VAS评分较治疗前评分均下降(P<0.05)。与F组比较,治疗后的各时间点,FB组治疗效果较好,疼痛缓解率高(P<0.05)。结论竖脊肌平面阻滞可有效缓解竖脊肌肌筋膜疼痛综合征患者的疼痛,治疗效果优于痛点阻滞。

腰交感神经节阻滞监测指标研究进展

腰交感神经节阻滞(lumbar sympathetic ganglion block,LSGB)是指使用物理方法或化学药物作用于腰交感神经节或神经链调控神经传导功能的技术。LSGB已广泛应用于各种神经病理性疼痛和血管性疾病的治疗,但是如何及时准确地判断阻滞成功尚需深入研究。本文对腰交感神经阻滞成功的监测方法进行综述,重点关注直接血流相关性与非血流相关性监测指标,以期为临床选择提供参考。

肝癌腹腔镜根治术后PCIA并胸椎旁神经阻滞的效果

目的探讨肝癌腹腔镜根治术后静脉自控镇痛(PCIA)并胸椎旁神经阻滞的效果。方法选取2021年3月—2023年2月河北省沧州中西医结合医院行腹腔镜肝癌根治术治疗的84例病人,随机分为观察组与对照组,每组42例。对照组采用常规阿片类药物静脉镇痛,观察组采用PCIA并胸椎旁神经阻滞镇痛。比较两组术后疼痛程度、Ramsay镇静评分、炎症因子、肝功能及不良反应等指标。结果观察组术后12、24、72h静息状态下疼痛评分及Ramsay镇静评分均显著低于对照组(F=2.930~13.850,P<0.05)。观察组术后72h肿瘤坏死因子-α、白细胞介素-6和降钙素原水平均显著低于对照组(F=6.139~8.961,P<0.05)。观察组术后72h谷草转氨酶、总胆红素和谷丙转氨酶水平均显著低于对照组(F=3.845~5.216,P<0.05)。观察组不良反应总发生率(7.14%)虽低于对照组(14.29%),但两组差异无统计学意义(χ^(2)=1.120,P>0.05)。结论肝癌腹腔镜根治术后应用PCIA并胸椎旁神经阻滞能显著提升镇痛和镇静效果,减轻炎症反应,降低肝功能损伤,值得临床推广应用。

基于电荷耦合效应的超级结JBS二极管的仿真分析

为提升现代单极型功率二极管的性能,进一步突破“硅极限”,通过加大传统JBS二极管中P+区结深,引入超级结结构以减薄芯片厚度,缓解传统单极型器件通态压降与反向阻断电压之间的矛盾,提高单位面积器件的导通电流密度。使用数值方法分析了超级结JBS二极管中P柱区浓度、N柱区宽度和N柱区浓度对正向导通特性以及反向阻断特性的影响,应用电场耦合效应理论分析了超级结JBS二极管的正向导通和反向阻断机理,设计了一款300 V的超级结JBS二极管。

Pacemaker post transcatheter aortic valve replacement:A multifactorial risk?

Pacemaker post-transcatheter aortic valve replacement is related to multifactorial risk.Nwaedozie et al brought to the body of evidence electrocardiogram and clinical findings.However,procedural characteristics have at least as much impact on the final need for a permanent pacemaker and potentially on the pacing rate.In this regard,long-term follow-up and understanding of the impact of long-term stimulation is of utmost importance.