Oxidation behavior of 4774DD1 Ni-based single-crystal superalloy at 980℃ in air

The oxidation behavior of a novel Ni-based single-crystal 4774DD1 superalloy for industrial gas turbine applications was investigated by the isothermal oxidation at 980℃ and discontinuous oxidation weight gain methods.The phase constitution and morphology of surface oxides and the characteristics of the crosssection oxide film were analyzed by XRD,SEM and EDS.Results show that the oxidation kinetics of the 4774DD1 superalloy follows the cubic law,indicating its weak oxidation resistance at this temperature.As the oxidation time increases,the composition of the oxide film evolves as following:One layer consisting of a bottom Al_(2)O_(3)sublayer and an upper(Al_(2)O_(3)+NiO)mixture sublayer after oxidized for 25 h.Then,two layers composed of an outermost small NiO discontinuous grain layer and an internal layer for 75 h.This internal layer is consisted of the bottom Al_(2)O_(3)sublayer,an intermediate narrow CrTaO_(4)sublayer,and an upper(Al_(2)O_(3)+NiO)mixture sublayer.Also two layers comprising an outermost relative continuous NiO layer with large grain size and an internal layer as the oxidation time increases to 125 h.This internal layer is composed of the upper(Al_(2)O_(3)+NiO)mixture sublayer,an intermediate continuous(CrTaO_(4)+NiWO_(4))mixture sublayer,and a bottom Al_(2)O_(3)sublayer.Finally,three layers consisting of an outermost(NiAl2O_(4)+NiCr2O_(4))mixture layer,an intermediate(CrTaO_(4)+NiWO_(4))mixture layer,and a bottom Al_(2)O_(3)layer for 200 h.

Difficult airway due to cervical haemorrhage caused by spontaneous rupture of a parathyroid adenoma: A case report

BACKGROUND Cervical haemorrhage due to spontaneous rupture of a parathyroid adenoma is a rare complication that may cause life-threatening acute airway compromise.CASE SUMMARY A 64-year-old woman was admitted to the hospital 1 day after the onset of right neck enlargement, local tenderness, head-turning difficulty, pharyngeal pain, and mild dyspnoea. Repeat routine blood testing showed a rapid decrease in the haemoglobin concentration, indicating active bleeding. Enhanced computed tomography images showed neck haemorrhage and a ruptured right parathyroid adenoma. The plan was to perform emergency neck exploration, haemorrhage removal, and right inferior parathyroidectomy under general anaesthesia. The patient was administered 50 mg of intravenous propofol, and the glottis was successfully visualised on video laryngoscopy. However, after the administration of a muscle relaxant, the glottis was no longer visible and the patient had a difficult airway that prevented mask ventilation and endotracheal intubation. Fortunately, an experienced anaesthesiologist successfully intubated the patient under video laryngoscopy after an emergency laryngeal mask placement. Postoperative pathology showed a parathyroid adenoma with marked bleeding and cystic changes. The patient recovered well without complications.CONCLUSION Airway management is very important in patients with cervical haemorrhage. After the administration of muscle relaxants, the loss of oropharyngeal support can cause acute airway obstruction.Therefore, muscle relaxants should be administered with caution. Anaesthesiologists should pay careful attention to airway management and have alternative airway devices and tracheotomy equipment available.

基于Aspen Plus的化工热力学教学——原始UNIFAC及UNIFAC(Dortmund)模型计算活度系数

化工生产中涉及诸多化学物质,仅靠实验手段测定所有溶液的性质是不可能的。UNIFAC作为一种半经验的基团贡献法,是在缺少实验数据的情况下,预测活度系数及相平衡的有效方法。采用Aspen Plus软件,选择原始UNIFAC模型及UNIFAC(Dortmund)模型计算液体混合物组分活度系数,能够有效简化计算过程,提高教学效率,对于提高学生的应用能力、加深学生对概念的理解也有重要作用。

永磁无刷直流电机性能的影响因素的数学推导与仿真分析

在理论上推导出电机性能的影响因素是科学设计电机的前提。为了在理论上推导出影响永磁无刷直流电机的电磁转矩和电磁效率的影响因素,并用虚拟仿真加以验证,按照电机学的粘性阻尼理论,结合电磁学基本原理推导了电磁转矩和电磁效率关于各设计变量的公式。通过公式可以发现,此类电机的电磁转矩和电磁效率可用多元函数来表达,两者的决定性因素是额定电压、平均半匝长系数、永磁体厚度、极数和气隙等设计参数,并且经过数学分析可以得到电磁转矩和效率关于各设计变量的变化趋势。为了进一步证实理论推导的正确性,ANSYS Electronics Desktop软件的RMxprt模块进行了此类电机性能影响因素的仿真分析,分析结果与理论研究基本一致。这些趋势可以为永磁无刷直流电机研发人员选取优化设计变量和调整变量的数值提供方向。

永磁无刷直流电机的多目标优化研究

CVVL电机是一种用于提升发动机性能、降低汽车耗油量的一款永磁无刷直流电机,以其为研究对象,以提高转子输出转矩、电机效率、降低转矩脉动和定子槽满率为优化目标,以永磁体厚度、转子外径、定子内径、定子槽身宽和定子槽身高5个对优化目标影响最大的结构参数为优化变量,利用仿真软件ANSYS平台对永磁无刷直流电机结构作多目标优化,得到最优解集,最后通过仿真和试验验证优化方法的可行性,结果表明优化后的电机性能全面提升,满足优化目标,本文的多目标优化方法可为永磁无刷直流电机的结构优化提供参考。

Embedded BCI Rehabilitation System for Stroke

In stroke rehabilitation,rehabilitation equipments can help with the training.But traditional equipments are not convenient to carry,which limits patients to use related rehabilitation techniques.To solve this kind of problem,a new embedded rehabilitation system based on brain computer interface(BCI)is proposed in this paper.The system is based on motor imagery(MI)therapy,in which electroencephalogram(EEG)is evoked by grasping motor imageries of left and right hands,then collected by a wearable device.The EEG is transmitted to a Raspberry Pie processing unit through Bluetooth and decoded as the instructions to control the equipment extension.Users experience the limb movement through the visual feedback so as to achieve active rehabilitation.A pilot study shows that the user can control the movement of the rehabilitation equipment through his mind,and the equipment is convenient to carry.The study provides a new way to stroke rehabilitation.

PCB酸性蚀刻液中缓蚀剂对厚铜线路制作的影响(英文)

以2-巯基苯并噻唑(2-MBT)、苯并三氮唑(BTA)和苯氧基乙醇(MSDS)作为缓蚀剂,研究了其加入在酸性蚀刻液后对PCB厚铜线路的缓蚀效果。通过接触角测试、电化学测试和蚀刻因子得出缓蚀状态,并结合扫描电子显微镜观察铜表面形貌。通过分子动力学计算和量子化学模拟分析缓蚀剂在铜表面的吸附机理。结果表明,2-MBT+MSDS与BTA+MSDS的分子结构可有效地平行吸附在铜表面,且吸附能高于单一缓蚀剂。加入了2-MBT+MSDS的蚀刻液,对厚度约为33μm铜线路进行刻蚀,铜线路的蚀刻因子提高到6.59,可有效应用于PCB厚铜线路制作。

Prevalence of post-traumatic stress disorder after earthquakes among the elderly in China: A meta-analysis

BACKGROUND: The study aims to investigate the occurrence of post-traumatic stress disorder(PTSD) after earthquakes among the elderly. METHODS: Data from cross-sectional studies focusing on the prevalence of PTSD after earthquakes among the elderly were collected from Pub Med, EMBASE, Cochrane Library, and China National Knowledge Infrastructure in December 2019. The search terms included post-traumatic stress disorder, earthquake, and elderly. This study used Review Manager 5.0 to evaluate the impact of the results. In addition, forest plots, sensitivity analysis, and bias analysis were carried out on the included articles. The combined estimate of the risk ratio and the standard deviation of the 95% confidence interval(95% CI) were measurements of the size of the effect.RESULTS: There were 4,834 patients included from 10 eligible studies. The sample sizes of PTSD group and non-PTSD group were 1,277 and 3,557, respectively. The meta-analysis showed that the overall occurrence of PTSD after earthquakes among the elderly was 0.25;the occurrence in females was higher than that in males, and the occurrence in the same province indicated little difference(Wenchuan city 0.25 and Ya'an city 0.24).CONCLUSIONS: After earthquakes, the occurrence of PTSD is higher among the elderly than among other age groups, and higher among the females than among the males, while there is little difference among different areas within the same province. This indicated that prioritized specific psychological interventions should be provided to the aged and the females.

计算机网络安全问题及其防范策略研究

网络是把“双刃剑”,到目前为止,计算机的更新换代可以说是一个极速的状态,网络使人们的交流更加方便,但随着其发展,出现的问题也越来越明显,网络安全的弱化对个人信息以及财产安全问题都有可能会产生损失。因此,文章就计算机网络的便利和产生的问题及其防范策略进行研究讨论。

信用评级差异与企业关联交易行为

本文从融资约束的角度出发,研究上市公司与其第一大股东的主体信用评级差异对集团内部双方关联拆借金额的影响,以考察信用评级在我国上市公司内部资本市场的作用。研究发现,当上市公司和第一大股东都有主体信用评级时,二者的主体信用评级差异越大,关联拆借的金额也就越大;当二者中仅一方有主体信用评级时,资金会从有评级的一方拆出到无评级的另一方,且主体信用评级与关联拆借金额正相关。进一步研究还发现,主体信用评级差异与关联拆借金额的这种正向相关在国有上市公司和西部地区上市公司中更加显著。总体来看,上市公司与其第一大股东之间的主体信用评级差异,为通过关联拆借实现集团内部融资成本最小化提供了条件。本文丰富了企业关联交易的影响因素研究,拓展了信用评级与内部资本市场领域的相关探讨,为我国信用评级行业的发展提供了理论指导。

一种基于双忙音多址接入的无线自组网IDBTMA协议研究

无线自组网技术在未来数字化战场中将发挥巨大的作用,尤其对无人机集群作战有重要的影响。在双忙音多址接入(DBTMA)协议的基础上对无线自组织网络接入协议进行了研究,提出了一种改进型的DBTMA协议,模拟仿真了该协议在不同网络流量下的性能。结果显示,与ALOHA协议、CSMA/CA协议相比,该协议的信道利用率更高,平均时延更小。

Impact of Accumulated Temperature on Wetland Vegetation Area in Poyang Lake

Accumulated temperature,which is now widely used in agronomy,is an important ecological factor to the growth of plants,but few relative studies have been found on the vegetation area of floodplain grasslands in Poyang Lake.This research used the classification and regression tree(CART)to classify normalized vegetation area index derived from MODIS LAI(Moderate Resolution Imaging Spectroradiometer Leaf Area Index)images from 2008 to 2014,according to different climate indexes,such as mean daily air temperature(n),accumulated temperature(jw),daily maximum temperature(g),daily minimum temperature(d),accumulative precipitation(j),water level(s)and average water level for 20 days preceding(a).The results showed that:(1)The accumulated temperature and the 20-day average WL(water level)were found to have the greatest impact on variation in wetland vegetation area,and they both dominated the classification process twice;(2)Two classification thresholds of accumulated temperature were 790°C and 1784°C,approximately corresponding to the beginning of April and midMay;(3)790°C could also be used as a threshold to select remote sensing images to analysis the annual variability of vegetation,i.e.while accumulated temperature is lower than 790°C,remote sensing images of similar accumulated temperature rather than similar date should be selected from different years for comparison.We also found that,effects of different hydrological factors on area of floodplain grasslands showed stage characteristics:(1)From January to March,water level changes slowly with less rainfall,as a result,the 20-day average WL which can interpret the hydrologic characteristics smoothly showed significant importance in this stage;(2)While entering April,intense rainfall make accumulative precipitation to be the dominating factor of classification;(3)From late April to mid-May,in condition of accumulative precipitation higher than 405 mm,daily water level is of most importance,because to the flood recession process as well as rapid water level fluctuations.

Photothermal-chemical synthesis of P-S-H ternary hydride at high pressures

The recent discovery of room temperature superconductivity(283 K)in carbonaceous sulfur hydride(C-S-H)has attracted much interest in ternary hydrogen rich materials.In this report,ternary hydride P-S-H was synthesized through a photothermal-chemical reaction from elemental sulfur(S),phosphorus(P)and molecular hydrogen(H_(2))at high pressures and room temperature.Raman spectroscopy under pressure shows that H_(2)S and PH_(3) compounds are synthesized after laser heating at 0.9 GPa,and a ternary van der Waals compound P-S-H is synthesized with further compression to 4.6 GPa.The P-S-H compound is probably a mixed alloy of PH_(3) and(H_(2)S)_(2)H_(2) with a guest-host structure similar to the C-S-H system.The ternary hydride can persist up to 35.6 GPa at least and shows two phase transitions at approximately 23.6 GPa and 32.8 GPa,respectively.

Raman spectroscopy investigation on the pressure-induced structural and magnetic phase transition in two-dimensional antiferromagnet FePS_(3)

The layered van der Waals antiferromagnetic Fe PS_(3) has received considerable attention because long range magnetic ordering can remain with single atoms layer,which offers potential applications in future ultrathin devices.Here,we perform Raman spectroscopy to systematically explore the variations of lattice vibration and crystal structure under pressure up to 18.9 GPa.We observe two structural phase transitions at approximately 4 GPa and 13 GPa,respectively.Moreover,by monitoring spin-related Raman modes,we demonstrate a pressure-induced magnetic structure transition above 2 GPa.These modes disappear accompanying the second structural phase transition and insulator-to-metal transition(IMT),indicating the suppression of long-range magnetic ordering,in agreement with earlier neutron powder diffraction experiments.

E3GCAPS: Efficient EEG-Based Multi-Capsule Framework with Dynamic Attention for Cross-Subject Cognitive State Detection

Cognitive state detection using electroencephalogram(EEG)signals for various tasks has attracted significant research attention.However,it is difficult to further improve the performance of crosssubject cognitive state detection.Further,most of the existing deep learning models will degrade significantly when limited training samples are given,and the feature hierarchical relationships are ignored.To address the above challenges,we propose an efficient interpretation model based on multiple capsule networks for cross-subject EEG cognitive state detection,termed as Efficient EEG-based Multi-Capsule Framework(E3GCAPS).Specifically,we use a selfexpression module to capture the potential connections between samples,which is beneficial to alleviate the sensitivity of outliers that are caused by the individual differences of cross-subject EEG.In addition,considering the strong correlation between cognitive states and brain function connection mode,the dynamic subcapsule-based spatial attention mechanism is introduced to explore the spatial relationship of multi-channel 1D EEG data,in which multichannel 1D data greatly improving the training efficiency while preserving the model performance.The effectiveness of the E3GCAPS is validated on the Fatigue-Awake EEG Dataset(FAAD)and the SJTU Emotion EEG Dataset(SEED).Experimental results show E3GCAPS can achieve remarkable results on the EEG-based cross-subject cognitive state detection under different tasks.

Anti-programmed cell death ligand 1-based immunotherapy in recurrent hepatocellular carcinoma with inferior vena cava tumor thrombus and metastasis:Three case reports

BACKGROUND Recurrent hepatocellular carcinoma(HCC)with inferior vena cava tumor thrombus is a great challenge for oncologists and has a poor prognosis.To date,the safety and efficacy of programmed cell death ligand 1(PD-L1)inhibitors are still unknown.CASE SUMMARY A 59-year-old male was identified as having a tumor thrombus in the inferior vena cava 3 years after surgery.The patient underwent a second surgery and adjuvant chemotherapy.However,the level of alpha-fetoprotein was elevated after 2 mo,and lung metastases and mediastinal lymph node metastases were identified.The expression of PD-L1 in HCC and inferior vena cava tumor thrombus tissues was analyzed by immunohistochemistry.Then,the patient received atezolizumab immunotherapy.The level of alpha-fetoprotein dropped to normal,the mediastinal lymph node metastases decreased in size and the lung metastases disappeared after 3 mo of immunotherapy.The patient had no signs of recurrence at 21 mo of follow-up.A 60-year-old male underwent left hepatic tumor resection,inferior vena cava incision and thrombus removal,followed by regular chemotherapy.The patient developed lung and splenic metastases after surgery.Pembrolizumab was used for six courses,and the splenic metastasis shrank,after which splenectomy was performed.The patient continued to receive pembrolizumab for thirteen courses,and the lung metastases showed no progression.A 34-year-old male was diagnosed with liver cancer with inferior vena cava tumor thrombus.The patient underwent right hepatectomy and received tislelizumab for three courses.He is still receiving immunotherapy and in good condition.CONCLUSION Anti-PD-L1 therapy in HCC patients with inferior vena cava tumor thrombus and metastasis is associated with relatively good patient outcomes.

Psychological and Emotional Responses during Different Stages of the COVID-19 Pandemic Based on a Survey of a Mental Health Hotline

Background:The coronavirus(COVID-19)outbreak in 2019 triggered psychological and emotional responses.This research investigates the psychological status and emotional problems of those who sought psychological assistance during the epidemic period by calling a mental health hotline.Methods:This study aims to combine qualitative and quantitative research.Descriptive analysis was used for undertaking qualitative research.We ana-lyzed the data from group 1(n=706),in which the people used the mental health hotline from 25 January 2020 to 23 June 2020.A self-designed questionnaire was developed in accordance with the classification and sum-marized items from group 1’s psychological problems and emotional status.To implement the quantitative research,we conducted a cross-sectional descriptive survey and used the self-compiled scale and HADS to inves-tigate group 2(n=553)from May 2020 to June 2020.Results:Descriptive statistics and comparative analysis revealed that:①Visitors mainly reported behavior,emotional,family relationship problems and sleep disorders.②Anxiety,comorbidities,sleep disorders and coping problems were the most frequently reported problems.③There were significant differences in the number of visitors experiencing various problems or exhibiting harmful behaviors(sorrow,worry,fear,depression,sleep disorders,self-harm or suicide,and coping problems,anxiety,hypochondria,and comorbidity)in the four stages of the epidemic.④More than a quarter of participants still suffered from anxiety or depression in the later stages of the epidemic.Conclusion:Different problems manifested at different stages of the epidemic,and psychological interventions and assistance should be tailored to reflect this.

无人机自适应航迹规划研究

无人机航迹在线规划对无人机的反应能力有重要的影响,在航迹修正算法的基础上对无人机航迹在线规划进行了研究,提出了一种自适应航迹规划算法,模拟了无人机处于不同的性能情况下对该算法产生的影响。结果显示,该算法能够引导飞机规避障碍物,具有结构简单、计算效率高的特点,并且能够自适应。

乳头状肾细胞癌单中心11年临床诊治与预后分析

目的分析不同分型乳头状肾细胞癌(pRCC)的临床特征及治疗效果,探讨pRCC预后相关危险因素。方法回顾性收集了中山大学孙逸仙纪念医院2011年1月至2021年10月经微创手术治疗且病理确诊的70例pRCC患者的临床及病理资料。所有患者术前已排除远处转移,并对患者生存及复发转移情况进行跟踪随访,随访至2021年12月底,以出现疾病进展或任何原因的死亡为终点。采用Kaplan-Meier法绘制生存曲线,COX回归用于多因素分析无进展生存(PFS)的危险因素。结果70例患者均诊断为pRCC,包括21例Ⅰ型及49例Ⅱ型,其中男55例,中位年龄57岁。中位肿瘤直径为4.0 cm(Q_(1)~Q_(3):2.9~6.3 cm)。肿瘤TNM分期:pT_(1)期52例,pT_(2)期7例,pT_(3)期10例及pT_(4)期1例,Ⅰ型及Ⅱ型患者肿瘤直径(4.0 cm vs 4.0 cm)及pT分期差异无统计学意义。Ⅰ型患者中1例伴癌栓,Ⅱ型患者中9例伴癌栓,7例淋巴结转移患者均为Ⅱ型。肿瘤侵犯肾包膜34例,含31例Ⅱ型(P<0.001),Ⅱ型患者WHO/ISUP分级显著高于Ⅰ型(P<0.001)。总体中位随访时间46个月,Ⅰ型和Ⅱ型pRCC患者中位随访时间分别为43个月和51个月。5年无进展生存率分别为100%和67.3%,Kaplan-Meier生存分析示Ⅰ型pRCC患者PFS优于Ⅱ型(P<0.05)。Cox多因素分析发现肿瘤直径与pRCC的PFS相关,此外术前碱性磷酸酶异常亦与Ⅱ型pRCC的PFS相关。结论Ⅱ型pRCC较Ⅰ型核分级更高,更易发生包膜入侵,更易发生疾病进展。直径较大的pRCC患者预后更差,术前碱性磷酸酶异常是Ⅱ型pRCC的独立危险因素。

青藏高原植被结构变化反映环境变迁

草地植被结构对于其生产和生态功能至关重要,但大尺度信息严重匮乏.本研究结合多源遥感数据和深度学习,在区域尺度上厘清了青藏高原高寒草地基于群系的植物群落结构空间格局,并比较了其历史变化.过去40年,高寒草甸在高寒草地中的比例从50%上升到69%,反映了变暖变湿的环境变化.此外,高寒草甸和高寒草原中高山嵩草草甸和紫花针茅草原的优势度分别增强到76%和92%.其中,气候因子驱动了紫花针茅草原近些年的分布;高山嵩草草甸近些年的分布则并非完全由气候驱动,人类活动可能起重要作用.本研究首次探索了区域尺度植被结构特征与历史变化,为认识青藏高原草地变化的驱动力及其空间异质性提供了新视角.