Prevention of thromboembolic events after radical prostatectomy in patients with hereditary thrombophilia due to a factor V Leiden mutation by multidisciplinary coagulation management

Objective:To examine the perioperative impact of factor V Leiden mutation on thromboembolic events'risk in radical prostatectomy(RP)patients.With an incidence of about 5%,factor V Leiden mutation is the most common hereditary hypercoagulability among Caucasians and rarer in Asia.The increased risk of thromboembolic events is three-to seven-fold in heterozygous and to 80-fold in homozygous patients.Methods:Within our prospectively collected database,we analysed 33006 prostate cancer patients treated with RP between December 2001 and December 2020.Of those,patients with factor V Leiden mutation were identified.All patients received individualised recommendation of haemostaseologists for perioperative anticoagulation.Thromboembolic complications(deep vein thrombosis and pulmonary embolism)were assessed during hospital stay,as well as according to patient reported outcomes within the first 3 months after RP.Results:Overall,85(0.3%)patients with known factor V Leiden mutation were identified.Median age was 65(interquartile range:61-68)years.There was at least one thrombosis in 53(62.4%)patients and 31(36.5%)patients had at least one embolic event in their medical history before RP.Within all 85 patients with factor V Leiden mutation,we experienced no thromboembolic complications within the first 3 months after surgery.Conclusion:In our cohort of patients with factor V Leiden mutation,no thromboembolic events were observed after RP with an individualised perioperative coagulation management concept.This may reassure patients with this hereditary condition who are counselled for RP.

Cohort study on the treatment of BRAF V600E mutant metastatic colorectal cancer with integrated Chinese and western medicine

BACKGROUND Patients with BRAF V600E mutant metastatic colorectal cancer(mCRC)have a low incidence rate,poor biological activity,suboptimal response to conventional treatments,and a poor prognosis.In the previous cohort study on mCRC conducted by our team,it was observed that integrated Chinese and Western medicine treatment could significantly prolong the overall survival(OS)of patients with colorectal cancer.Therefore,we further explored the survival benefits in the population with BRAF V600E mutant mCRC.AIM To evaluate the efficacy of integrated Chinese and Western medicine in the treatment of BRAF V600E mutant metastatic colorectal cancer.METHODS A cohort study was conducted on patients with BRAF V600E mutant metastatic colorectal cancer admitted to Xiyuan Hospital of China Academy of Chinese Medical Sciences and Traditional Chinese Medicine Hospital of Xinjiang Uygur Autonomous Region from January 2016 to December 2022.The patients were divided into two cohorts.RESULTS A total of 34 cases were included,with 23 in Chinese-Western medicine cohort(cohort A)and 11 in Western medicine cohort(cohort B).The median overall survival was 19.9 months in cohort A and 14.2 months in cohort B,with a statistically significant difference(P=0.038,hazard ratio=0.46).The 1-3-year survival rates were 95.65%(22/23),39.13%(9/23),and 26.09%(6/23)in cohort A,and 63.64%(7/11),18.18%(2/11),and 9.09%(1/11)in cohort B,respectively.Subgroup analysis showed statistically significant differences in median OS between the two cohorts in the right colon,liver metastasis,chemotherapy,and first-line treatment subgroups(P<0.05).CONCLUSION Integrated Chinese and Western medicine can prolong the survival and reduce the risk of death in patients with BRAF V600E mutant metastatic colorectal cancer,with more pronounced benefits observed in patients with right colon involvement,liver metastasis,combined chemotherapy,and first-line treatment.

Current concepts in ameloblastoma-targeted therapies in B-raf proto-oncogene serine/threonine kinase V600E mutation: Systematic review

BACKGROUND Ameloblastomas are common benign epithelial odontogenic neoplasms that present an aggressive and unpredictable behavior that may modify treatment strategies.Different signaling pathways that participate in the progression of these tumors have been identified.B-raf proto-oncogene serine/threonine kinase(BRAF)is a protein involved in the behavior of ameloblastomas,and it is related to many cell mechanisms.BRAF gene mutations have been identified in ameloblastomas,of which the BRAF V600E(valine substituted by glutamic acid at amino acid 600)mutation has been the most common and can be present concomitantly with other mutations that may be involved in its behavior.Targeted therapies have been used as an alternative in the case of resistance or contraindications to conventional treatments.AIM To document the presence of BRAF V600E and additional mutations,their behavior,and targeted therapies in these tumors.METHODS An electronic literature search was conducted according to PRISMA guidelines in PubMed/MEDLINE,Cochrane,EMBASE,and SpringerLink using the terms“ameloblastomas”,“BRAF V600E”,“additional mutations”,and“targeted therapies”.Ameloblastomas were classified according to WHO guidelines.Inclusion criteria were articles in English,published not more than 10 years ago,and studies with laboratory works related to BRAF V600E.Articles were evaluated by two independent reviewers and retrieved for full-text evaluation.The EBLIP Critical Appraisal Checklist was used to evaluate the quality of the eligible studies.Descriptive statistical analysis was performed.RESULTS Two independent reviewers,with a substantial concordance indicated by a kappa coefficient of k=0.76,evaluated a total of 19 articles that were included in this study.The analysis registered 521 conventional ameloblastomas(AM),81 unicystic ameloblastomas(UA),13 ameloblastic carcinomas(AC),three metastatic ameloblastomas(MA),and six peripheral ameloblastomas(PA),of which the histopathological type,anatomic location,laboratory tests,expression of BRAF mutation,and additional mutations were registered.The BRAF V600E mutation was found in 297 AM(57%),63 UA(77.7%),3 AC(23%),1 MA(50%),and 5 PA(83.3%).Follicular type predominated with a total of 116 cases(40%),followed by plexiform type with 63 cases(22.1%).Furthermore,both types presented additional mutations,in which alterations in JAK3 P132T,SMARCB1,PIK3CA,CTNNB1,SMO,and BRAF G606E genes were found.Four case reports were found with targeted therapy to BRAF V600E.CONCLUSION The identification of BRAF V600E and additional mutations as an aid in targeted therapies has been a breakthrough in alternative treatments of ameloblastomas where surgical treatments are contraindicated.

JAK2 V617F, MPL W515L and JAK2 Exon 12 Mutations in Chinese Patients with Primary Myelofibrosis

Objective： JAK2 V617F, MPL W515L and JAK2 exon 12 mutations are novel acquired mutations that induce constitutive cytokine-independent activation of the JAK-STAT pathway in myeloproliferative disorders （MPD）. The discovery of these mutations provides novel mechanism for activation of signal transduction in hematopoietic malignancies. This research was to investigate their prevalence in Chinese patients with primary myelofibrosis （PMF）. Methods： We introduced allele-specific PCR （AS-PCR） combined with sequence analysis to simultaneously screen JAK2 V617F, MPL W515L and JAK2 exon 12 mutations in 30 patients with PMF. Results： Fifteen PMF patients （50.0%） carried JAK2 V617F mutation, and only two JAK2 V617F-negative patients （6.7%） harbored MPL W515L mutation. None had JAK2 exon 12 mutations. Furthermore, these three mutations were not detected in 50 healthy controls. Conclusion： MPL W515L and JAK2 V617F mutations existed in PMF patients but JAK2 exon 12 mutations not. JAK2 V617F and MPL W515L and mutations might contribute to the primary molecular pathogenesis in patients with PMF.

Development of Fok-I based nested polymerase chain reaction-restriction fragment length polymorphism analysis for detection of hepatitis B virus X region V5M mutation

AIM: To develop a Fok-I nested polymerase chain reaction(PCR)-restriction fragment length polymorphism analysis(PRA) method for the detection of hepatitis B virus X region(HBx) V5 M mutation.METHODS: Nested PCR was applied into DNAs from 198 chronic patients at 2 different stages [121 patients with hepatocellular carcinoma(HCC) and 77 carrier patients]. To identify V5 M mutants, digestion of nested PCR amplicons by the restriction enzyme Fok-I(GGA TGN9↓) was done. For size comparison, the enzymetreated products were analyzed by electrophoresis on 2.5% agarose gels, stained with ethidium bromide, and visualized on a UV transilluminator.RESULTS: The assay enabled the identification of 69 patients(sensitivity of 34.8%; 46 HCC patients and 23 carrier patients). Our data also showed that V5 M prevalence in HCC patients was significantly higher than in carrier patients(47.8%, 22/46 patients vs 0%, 0/23 patients, P < 0.001), suggesting that HBx Ag V5 M mutation may play a pivotal role in HCC generation in chronic patients with genotype C infections.CONCLUSION: The Fok-I nested PRA developed in this study is a reliable and cost-effective method to detect HBx Ag V5 M mutation in chronic patients with genotype C2 infection.

Novel CYP4V2 mutations associated with Bietti crystalline corneoretinal dystrophy in Chinese patients

AIM: To analyze the CYP4V2 mutations in five unrelated Chinese patients with Bietti crystalline corneoretinal dystrophy（BCD） and to provide clinical features of these patients. BCD is a rare monogenic autosomal recessively inherited disorder characterized by the presence of crystals in the retina and retinal pigment epithelium atrophy. Mutations in the CYP4V2 gene have been found to be causative for BCD.METHODS: Ophthalmic examinations were carried out in the affected individuals. Peripheral blood samples were collected and genomic DNA was extracted. All exons and flanking intronic regions of the CYP4V2 gene were amplified with polymerase chain reaction and screened for mutations by direct DNA sequencing. One hundred control chromosomes were also screened to exclude nonpathogenic polymorphisms.RESULTS: Fundus examination revealed the presence of tiny yellowish-sparkling crystals at the posterior pole of the fundus and atrophy of the retinal pigment epithelium in all patients. Choroid neovascularization was noted in one patient. Five different CYP4V2 mutations were identified, including two missense mutations（p.F73 L,p.R400H）, two splice site mutations（c.802-8810del17ins GC, c.1091-2A 】G）, and one single base-pair deletion（p.T479 Tfs X7 or c.1437 del C）. The two splice site mutations were identified in three of the patients with BCD. Mutation p.T479 Tfs X7 was a novel mutation not observed in any of 100 ethnically matched control chromosomes.CONCLUSION: Mutation c.802-8810del17ins GC and c.1091-2A】G are common mutations in Chinese patientswith BCD. Our results expand the allelic heterogeneity of BCD.

BRAF V600E/TERT promoter mutations and NIS/TSHR expression in differentiated thyroid carcinomaand their clinical significance

Objective Telomerase reverse transcriptase(TERT) promoter mutations have recently been described in thyroid carcinoma.The purpose of this study was to investigate the clinical significance of(v-raf murine sarcoma viral oncogene homolog B1) BRAF V600 E and TERT promoter mutations in differentiated thyroid carcinoma(DTC).The relationship between the two mutations and NIS/TSHR expression was also analyzed.Methods We have detected BRAF V600 E and TERT promoter mutations by direct sequencing and NIS/TSHR expression by immunohistochemistry in 229 cases of DTC,52 cases of benign nodular goiter,and 31 cases of normal thyroid tissue.Results The BRAF V600 E mutation was detected in 142(62.0%) of 229 cases of DTC [141 cases of papillary thyroid carcinoma(PTC) and 1 case of follicular thyroid carcinoma(FTC)].TERT promoter mutations were detected in 18(7.9%) of 229 cases of DTC(14 cases of PTC and 4 cases of FTC),including the mutations C228T(0.9%) and C250T(7.0%),which were mutually exclusive.Moreover,11(61.1%) cases also harbored the BRAF V600 E mutation,which was not associated with gender,age,tumor size,lymph node metastasis,and recurrence risk stratification(P >0.05).The rate of TERT promoter mutation was higher in males,age ≥45,and in the middle/high-risk group(P <0.05),and the rate of simultaneous BRAF V600 E and TERT promoter mutations were higher in the middle/high-risk group(P <0.05).In addition,NIS positive rate in the concurrent BRAF V600 E and TERT promoter mutation group(45.5 %) was lower than in other groups(that is,the DTC group with BRAF V600 E or TERT promoter mutations(55.1%),the DTC group with no BRAF V600 E or TERT promoter mutation(57.5%),the nodules and normal group(75.9%);| r | = 0.171,P = 0.002).Conclusion TERT promoter mutations were lower in patients with DTC,with the C250 T mutation being the most common.The detection of BRAF V600 E mutation combined with TERT promoter mutations was instructive for the prognosis assessment and treatment of DTC.

Down Regulated Protein C Plasma Levels in the Absence of Factor V Leiden Mutation in HIV Patients: An Observational Study in Maiduguri, North-Eastern Nigeria

Background: As life expectancy of HIV-infected patients increases with use of highly active antiretroviral therapy (HAART), protean haematologic manifestation including decreased activity of natural anticoagulants such as protein C may occur in the absence of genetic risk factors. Based on this preposition, we assessed the plasma level of protein C, and prevalence of factor V Leiden mutation among HIV-infected individuals. Our cohort consisted of 499 HIV-infected patients, of which 250 had AIDS, while 249 were either asymptomatic or had minor mucocutaneous infection consistent with WHO clinical stages I and II without features of AIDS. We also evaluated 251 healthy, HIV-negative subjects as controls. All participants were tested for plasma protein C levels and factor V Leiden (FVL) mutation (Arg 506 Gln) by automation and amplification created restriction enzyme site (ACRES) polymerase chain reaction, respectively. The prevalence of reduced protein C plasma levels among HIV positive patients was 20%;it was more prevalent among those that had AIDS compared with those without features of AIDS, but within WHO clinical stage I and II, (93.3% vs 6.7%) respectively. None of the control patients had either reduced protein C nor FVL mutation. All participants that demonstrated reduced protein C plasma levels demonstrated normal FVL genotype (1691G/G). Conclusion: Decreased protein C plasma levels can occur in HIV-infected patients in the absence of factor V Leiden mutation. The risk increases with severity of the disease. Deranged protein C plasma level increases the risk of hypercoagulable state in patients with advanced HIV disease;it should be considered among the causes of thrombo embolism in this group of patients.

Contemporary treatment approaches for metastatic colorectal cancer driven by BRAF V600 mutations

The treatment of metastatic colorectal cancer(mCRC)harboring BRAF V600 mutations is challenging.These tumors are often refractory to standard treatment.Therefore,the patients may exhibit rapid clinical deterioration,depriving them of the chance to receive salvage therapy.In newly diagnosed patients with good performance status,the administration of an intensive chemotherapy regimen like FOLFOXIRI(5-fluorouracil,leucovorin,oxaliplatin,and irinotecan)along with the antiangiogenic agent bevacizumab can modify this aggressive behavior of the disease and improve patient clinical outcomes.The recently published results of the BEACON(Binimetinib,Encorafenib,and Cetuximab Combined to Treat BRAF-Mutant Colorectal Cancer)study demonstrated that a combination therapy consisting of BRAF,epidermal growth factor receptor,and mitogen-activated protein kinase kinase inhibitors could be a useful second-or third-line alternative.This review summarizes the current treatment strategies for BRAF-mutant mCRC.

Vaccines’ Safety and Effectiveness in the Midst of Covid-19 Mutations

We examined the coronavirus classification and evolution through its multiple mutations that have increased its transmissibility rate up to 70% globally, threatening to undermine the promise of a number of emerging vaccines that primarily focus on the immune detection of the Spike trimer. The safety and effectiveness of different vaccination methods are evaluated and compared, including the mRNA version, the Adenovirus DNA, Spike protein subunits, the deactivated virus genres, and the live attenuated coronavirus. Mutations have been long considered as random events, or mistakes during the viral RNA replication. Usually, what can go wrong will go wrong;therefore, repeated transformations lead to the extinction of a virus. On the contrary, the aggregate result of over 300,000 Covid-19 variants has expanded its transmissibility and infectiousness. Covid-19 mutations do not degrade the virus;they empower and facilitate its disguise to evade detection. Unlike other coronaviruses, Covid-19 amino acid switches do not reflect the random unfolding of errors that eventually eradicate the virus. Covid-19 appears to use mutations adaptively in the service of its survival and expansion. We cite evidence that Covid-19 inhibits the interferon type I production, compromising adaptive immunity from recognizing the virus. The deleterious consequences of the cytokine storm where the CD8+ killer cells injure the vital organs of the host may well be a Covid-19 manoeuvring to escape exposure. It is probable that evolution has programmed Covid-19 with an adeptness designed to debilitate key systemic defences to secure its subsistence. To date the infectiousness of the Covid-19 pandemic is exponentially increasing, denoting the possibility of an even more dangerously elusive, inconspicuous, and sophisticated version of the disease.

Covid-19 Mutations and the Effect of Different Vaccines on Immune Memory

We traced the coronavirus classification and evolution,analyzed the Covid-19 composition and its distinguishing characteristics when compared to SARS-CoV and MERS-CoV.Despite their close kinship,SARS-CoV and Covid-19 display significant structural differences,including 380 amino acid substitutions,and variable homology between certain open reading frames that are bound to diversify the pathogenesis and virulence of the two viral compounds.A single amino acid substitution such as replacing Aspartate(D)with Glycine(G)composes the D614G mutation that is around 20%more infectious than its predecessor 614D.The B117 variant,that exhibits a 70%transmissibility rate,harbours 23 mutants,each reflecting one amino acid exchange.We examined several globally spreading mutations,501.V2,B1351,P1,and others,with respect to the specific amino acid conversions involved.Unlike previous versions of coronavirus,where random mutations eventually precipitate extinction,the multiplicity of over 300,000 mutations appears to have rendered Covid-19 more contagious,facilitating its ability to evade detection,thus challenging the effectiveness of a large variety of emerging vaccines.Vaccination enhances immune memory and intelligence to combat or obstruct viral entry by generating antibodies that will prohibit the cellular binding and fusion with the Spike protein,restricting the virus from releasing its contents into the cell.Developing antibodies during the innate response,appears to be the most compelling solution in light of the hypothesis that Covid-19 inhibits the production of Interferon type I,compromising adaptive efficiency to recognize the virus,possibly provoking a cytokine storm that injures vital organs.With respect to that perspective,the potential safety and effectiveness of different vaccines are evaluated and compared,including the Spike protein mRNA version,the Adenovirus DNA,Spike protein subunits,the deactivated virus genres,or,finally,the live attenuated coronavirus that appears to demonstrate the greatest effectiveness,yet,encompass a relatively higher risk.

基于三基色LED的线性调光混合照明

为提供高品质、智能健康的照明光源,基于三基色LED光源构建了线性调光混合照明系统,并提出一种调光调色的优化方法。混合光源的光色度和光强度分别用色温和明度等级来设定,使得混合照明效果更加符合“人因照明”的需求。在系统的智能优化配光过程中,将色温转化为CIE u′v′色度坐标,明度转化为亮度,使优化计算更加精确。该系统采用线性调光的方式,既能有效避免混合光源闪烁带来的健康安全问题,配合优化算法又有效解决了线性调光色度漂移大的问题。实验结果表明,在2000 K~8000 K的色温范围内,混合照明系统混合光的色度稳定性保持在1阶CIE u′v′圆内,在对应色温下的整个光强度调节范围内无可察觉的色差。采用线性调光方式在保持光色度稳定上比脉冲宽度调光方式效果更佳。理论探究和实验结果表明该混光照明系统简易可行,具有较高的实用价值。

15例遗传性凝血因子V缺陷症先证者的临床特征与基因突变分析

目的分析15个遗传性凝血因子V(FV)缺陷症先证者的临床特征与基因突变类型,初步探讨其可能的分子致病机制。方法采用一期凝固法和ELISA法分别检测FV活性(FV:C)和FV抗原(FV:Ag)。用PCR扩增患者F5基因的25个外显子及其侧翼序列,并直接测序。利用蛋白质模型分析其可能的分子机制。结果在5例FV:C大于10%的先证者中,仅有1例出现轻微出血症状;在10例FV:C小于10%的先证者中,7例表现出各种出血症状。15例先证者共检出12个基因突变位点(其中8个为新的突变,1个为致病的多态性)。蛋白质模型分析表明,所有6种错义突变都会导致FV蛋白的构象改变,其中2种(p.Ser1781Arg和p.Asp96His)会减少氢键数量,从而导致局部蛋白质结构不稳定。结论这些遗传性FV缺陷症先证者的FV水平与各自的F5基因突变有关,其FV水平与出血症状具有较强的相关性。

Acute upper gastrointestinal bleeding due to portal hypertension in a patient with primary myelofibrosis:A case report

BACKGROUND Acute upper gastrointestinal bleeding is a common medical emergency that has a 10%hospital mortality rate.According to the etiology,this disease can be divided into acute varicose veins and nonvaricose veins.Bleeding from esophageal varices is a life-threatening complication of portal hypertension.Portal hypertension is a clinical syndrome defined as a portal venous pressure that exceeds 10 mmHg.Cirrhosis is the most common cause of portal hypertension,and thrombosis of the portal system not associated with liver cirrhosis is the second most common cause of portal hypertension in the Western world.Primary myeloproliferative disorders are the main cause of portal venous thrombosis,and somatic mutations in the Janus kinase 2 gene(JAK2 V617F)can be found in approximately 90% of polycythemia vera,50% of essential thrombocyrosis and 50% of primary myelofibrosis.CASE SUMMARY We present a rare case of primary myelofibrosis with gastrointestinal bleeding as the primary manifestation that presented as portal-superior-splenic mesenteric vein thrombosis.Peripheral blood tests revealed the presence of the JAK2 V617F mutation.Bone marrow biopsy ultimately confirmed the diagnosis of myelofibrosis(MF-2 grade).CONCLUSION In patients with acute esophageal variceal bleeding due to portal hypertension and vein thrombosis without cirrhosis,the possibility of myeloproliferative neoplasms should be considered,and the JAK2 mutation test should be performed.

U75V钢轨钢耦合损伤循环塑性本构模型研究

针对我国重载铁路和地铁用钢在实际服役过程中的全寿命棘轮行为,开展U75V钢轨钢耦合损伤循环塑性本构模型研究。首先通过不同平均应力和不同应力幅值的循环实验,研究U75V钢轨钢在室温下的全寿命棘轮行为;然后基于损伤力学和循环塑性框架,采用损伤修正的Chaboche随动硬化模型,引入指数型损伤演化律,建立耦合损伤的循环塑性本构模型;最后针对材料的失效模式,建立基于损伤临界值的疲劳失效判据,预测失效寿命。研究结果表明,模拟循环稳定时的棘轮应变率误差小于22.0%,失效时的棘轮应变误差小于38.0%;预测U75V钢轨钢的低周疲劳寿命均在1.5倍误差带内。总的来说,该耦合损伤循环塑性本构模型能描述U75V钢轨钢在非对称单轴应力循环下的全寿命棘轮行为。

百米U75V钢轨在线热处理工艺优化

百米U75V钢轨是我国铁路建设的主型钢轨,在线热处理是其主要强韧化手段,纵向(长度方向)性能均匀性差和生产效率低是其热处理生产存在的主要问题。百米U75V钢轨的在线热处理过程分为2个冷却阶段,共包含4个冷却工艺参数:开淬温度(T_(i))、相变阶段冷却速度(V_(s))、相变冷却结束温度(T_(f))以及相变后冷却速度(V_(a))。通过热模拟试验研究了各参数对百米U75V钢轨组织和性能的影响。随着工艺参数的变化,珠光体片层间距(S)在100.7~209.1 nm范围内变化;T_(i)和V_(s)对S具有特别显著影响,T_(f)和V_(a)对S没有显著影响;T_(i)不一致是百米U75V钢轨纵向性能不均匀的主要原因之一。采用“先慢后快”的两段式冷却方案,即在轧后钢轨表面温度冷却至相变终冷温度(约500℃)之前,以接近但不超过珠光体转变临界冷却速率的速度进行冷却,之后提高冷却速度(不超过10℃/s),有利于同时提高生产效率和百米U75V钢轨纵向性能的均匀性。

心肌钠通道Na_(V)1.5在心律失常中的作用

心律失常(cardiac arrhythmias)是世界范围内发病率和死亡率较高的心血管疾病之一,与心脏中离子通道功能破坏以及电信号在心肌细胞的传导异常有关。心肌钠通道Na_(V)1.5(cardiac sodium channel Na_(V)1.5)参与心肌细胞动作电位的启动和兴奋的传导,基因突变所致的Na_(V)1.5通道表达和调控异常是心律失常发生的重要生物学基础。本文综合国内外关于Na_(V)1.5通道结构和功能的介绍及通道异常表达时心律失常的研究现状,为心血管药物的研发和临床应用以及药物心脏毒性等的研究提供重要的理论依据。

U75V钢轨自然空冷过程的温度及固态相变特性

在线热处理是百米U75V钢轨的主要强韧化手段。热处理过程中会出现由于钢轨纵向(长度方向)不同位置进入热处理机组前所经历的自然空冷时间不同而导致纵向开淬温度不一致的问题。开淬温度是影响百米钢轨纵向性能均匀性的重要因素。研究了U75V钢轨轧后自然空冷过程的温度和固态相变特性。按目前生产流程,钢轨轧制和热处理工艺间的时间间隔应小于238 s。生产时采用对轧后钢轨的后端适当补热以及缩短轧制和热处理的时间间隔等方法来减小钢轨纵向开淬温差,有利于提高百米钢轨纵向性能均匀性。

喷风工艺参数对钢轨双频电正火温度场影响的数值模拟研究

由于钢轨闪光对焊后接头存在晶粒粗大等问题,无法满足性能要求,因此必须进行焊后热处理。常见焊后热处理一般分为两部分,即感应加热与喷风冷却,喷风冷却会通过冷速影响接头组织,在焊后热处理中占据重要地位。为了探究该过程,本文基于流体仿真软件FLUENT对U75V钢轨焊后热处理的喷风冷却过程进行数值模拟。仿真结果表明,正火喷风冷却时,轨腰与轨头的交界处上端出现最低流场流速,冷却速度较低,轨底两侧的流场流速最高,冷却速度最快。正火喷风冷却时的温度场具有以下分布特点。一是轨头与轨底中心温度高,轨腰温度低,三者的散热能力从高到低依次是轨底、轨腰、轨头;二是在喷风盒不同位置处采用不同喷风压力,采用降低轨腰与轨底的喷风压力、增加轨头的喷风压力的方法能够获得较好的冷却效果。

超声引导下细针穿刺细胞学、鼠类肉瘤病毒癌基因同源物B V600E基因突变单独及联合检测对甲状腺癌的诊断价值

目的探讨超声引导下细针穿刺(FNA)细胞学、鼠类肉瘤病毒癌基因同源物B(BRAF)V600E基因突变单独及联合检测对甲状腺癌的诊断价值。方法选取127例甲状腺结节患者,均接受超声引导下FNA细胞学、BRAF V600E基因突变检测,以病理检查结果为金标准,评估FNA细胞学、BRAF V600E基因突变单独及联合检测对甲状腺癌的诊断价值;采用Kappa检验评估FNA细胞学、BRAF V600E基因突变单独及联合检测诊断甲状腺癌的结果与病理检查结果的一致性。结果FNA细胞学、BRAF V600E基因突变联合检测诊断甲状腺癌的灵敏度为98.06%,特异度为100%,准确度为98.43%,阳性预测值为100%,阴性预测值为92.31%,均高于二者单独检测。FNA细胞学、BRAF V600E基因突变联合检测诊断甲状腺癌的结果与病理检查结果的一致性极高(Kappa=0.950),高于BRAF V600E基因突变(Kappa=0.877)和FNA细胞学(Kappa=0.772)单独检测。病理检查结果显示,阳性(甲状腺癌)103例,阴性24例,分别作为恶性组和良性组。恶性组患者FNA细胞学检测评分明显高于良性组,BRAF V600E基因突变检测CT值明显低于良性组,差异均有统计学意义(P﹤0.01)。结论FNA细胞学、BRAF V600E基因突变联合检测对甲状腺癌具有较高的诊断价值。