航空刹车材料一家人的跨年夜

20世纪初,在汽车刹车材料的启发下,航空刹车材料应运而生。它凭借自己优异的稳定性、良好的耐磨性和能在复杂环境下工作等优势,成功地在材料界站稳脚跟。近几年,我国科技发展势头良好,特别是在民用和军用航空航天研发领域,我国的科学技术水平已经迈入世界前列,航空刹车材料也再一次迎来了属于自己的高光时刻。本文采用拟人化的手法,以家庭年夜饭为题来介绍航空刹车材料的发展历程、化学工艺等相关知识。

Predicting depression in patients with heart failure based on a stacking model

BACKGROUND There is a lack of literature discussing the utilization of the stacking ensemble algorithm for predicting depression in patients with heart failure(HF).AIM To create a stacking model for predicting depression in patients with HF.METHODS This study analyzed data on 1084 HF patients from the National Health and Nutrition Examination Survey database spanning from 2005 to 2018.Through univariate analysis and the use of an artificial neural network algorithm,predictors significantly linked to depression were identified.These predictors were utilized to create a stacking model employing tree-based learners.The performances of both the individual models and the stacking model were assessed by using the test dataset.Furthermore,the SHapley additive exPlanations(SHAP)model was applied to interpret the stacking model.RESULTS The models included five predictors.Among these models,the stacking model demonstrated the highest performance,achieving an area under the curve of 0.77(95%CI:0.71-0.84),a sensitivity of 0.71,and a specificity of 0.68.The calibration curve supported the reliability of the models,and decision curve analysis confirmed their clinical value.The SHAP plot demonstrated that age had the most significant impact on the stacking model's output.CONCLUSION The stacking model demonstrated strong predictive performance.Clinicians can utilize this model to identify highrisk depression patients with HF,thus enabling early provision of psychological interventions.

钢结构模块建筑挤压式竖向自锁连接节点设计研究

在“双碳”背景下,具有工厂预制、快速建造、绿色低碳、可循环使用等优点的钢结构模块建筑已成为建筑工业化的发展热点。该建筑体系中节点设计对现场施工效率有着重要影响。针对钢结构模块建筑角柱连接节点,借鉴弹簧卡扣的基本原理,进行了既兼顾节点受力需求又构造简单的自锁式连接节点设计研究。系统论述了该节点的基本原理、构造及强度设计、加工制作方法等,采用有限元数值模拟软件对该节点的基本受力性能进行了分析研究;分析了该节点的优缺点,给出了现场施工安装方法,同时提供了解锁构造设计及水平互联竖向自锁节点构造设计等附加功能构造设计。该节点在满足受力需求的前提下,具有原理清晰、构造简单、不需要施工操作空间、无需留设施工孔、无开洞削弱、可快速装配等优点,为钢结构模块建筑的节点设计和研究提供了有益参考。

模块化单元房轻型楼盖人致振动响应与舒适度评价研究

轻型模块化单元房建筑中常采用冷弯薄壁轻钢龙骨复合预制板面层的组合楼盖系统。然而,该楼盖系统对人致振动响应的敏感度高,且目前缺乏足够的振动性能参考数据。为研究该轻型楼盖的振动性能,基于某实际模块化公寓项目,对建造前工厂试制的初制楼盖和实际工程应用的楼盖分别开展了振动频率和人行激励下的动力响应测试,参考现有规范和指南要求进行了楼盖舒适度评定并给出合理的评价指标建议。结果表明,楼盖的固有频率和人致振动响应受到楼盖跨度和面层刚度的显著影响,且随楼层升高楼盖自振频率降低;相较于纵向行走模式,横向行走模式更易引发楼盖的振动响应;多人非同频行走所引发的振动响应低于多人同频行走。建议以固有频率复合均方根加速度限值为指标,实现对模块化单元房楼盖振动性能的科学有效控制,从而提升模块建筑的居住舒适性,促进模块建筑的推广应用。

Microphone Array Speech Enhancement Based on Tensor Filtering Methods

This paper proposes a novel microphone array speech denoising scheme based on tensor filtering methods including truncated HOSVD(High-Order Singular Value Decomposition), low rank tensor approximation and multi-mode Wiener filtering. Microphone array speech signal is represented in three-order tensor space with channel, time, and spectrum modes and then tensor filtering model can be designed to process the multiway array data. As to the first method, noise can be reduced through the truncated HOSVD which is a simple scheme in tensor processing. It is more accurate to find the lower-rank approximation of the three-order tensor with Tucker model. Then MDL(Minimum Description Length) criterion is used to estimate the optimal tensor rank in the second method. Further, multimode Wiener filtering approach upon tensor analysis can be considered as the spanning of one-mode wiener filtering. How to take advantages of tensor model to obtain a set of filters is the heart of the novel scheme. The performances of the proposed three approaches are evaluated with objective indexes and listening quality test. The experimental results indicate that the proposed tenor filtering methods have potential ability of retrieving the target signal from noisy microphone array signal and the multi-mode Wiener filtering method provides the best denoising results among the three ones.

Prognostic value of lymph node metastasis in patients with T1-stage colorectal cancer from multiple centers in China

AIM To explore the features and prognostic value of lymph node metastasis in patients with T1-stage colorectal cancer(CRC).METHODS In all,321 cases of T1-stage CRC were selected from 10132 patients with CRC who received surgical therapy in six large-scale hospitals in China and were retrospectively analyzed. Univariate and multivariate analyses were performed to analyze the risk factors for lymphatic metastasis. A survival analysis was then performed to analyze the prognostic value of lymph node metastasis.RESULTS The occurrence rate of T1 stage was 3.17%(321/10132);of these patients,the lymph node metastasis rate was 8.41%(27/321),and the non-lymph node metastasis rate was 91.59%(294/321). Univariate analysis showed that preoperative serum CEA,preoperative serum CA199,preoperative serum CA724,vascular invasion,and degree of differentiation were associated with lymph node metastasis in T1-stage CRC(P < 0.05 for all). Multivariate analysis indicated that preoperative serum CA724,vascular invasion,and degree of differentiation were closely related to lymph node metastasis(P < 0.05 for all). Log-rank survival analysis showed that age,preoperative serum CEA,preoperative serum CA199,vascular invasion,degree of differentiation,and lymph node metastasis(χ2 = 24.180,P < 0.001) were predictors of 5-year overall survival(OS)(P < 0.05 for all). COX regression analysis demonstrated that preoperative serum CA199 and lymph node metastasis(HR = 5.117;P < 0.05;95%CI: 0.058-0.815) were independent prognostic indicators of 5-year OS in patients with T1-stage CRC(P < 0.05 for both). CONCLUSION The morbidity of T1-stage CRC was 3.17% for all CRC cases. Preoperative serum CA724,vascular invasion,and degree of differentiation are independent risk factors for lymph node metastasis. Lymph node metastasis is an independent prognostic factor for OS in patients with T1-stage CRC.

Propofol postconditioning ameliorates hypoxia/reoxygenation induced H9c2 cell apoptosis and autophagy via upregulating forkhead transcription factors under hyperglycemia

Background:Administration of propofol,an intravenous anesthetic with antioxidant property,immediately at the onset of post-ischemic reperfusion(propofol postconditioning,P-PostC) has been shown to confer cardioprotection against ischemia–reperfusion(I/R) injury,while the underlying mechanism remains incompletely understood.The forkhead box O(FoxO) transcription factors are reported to play critical roles in activating cardiomyocyte survival signaling throughout the process of cellular injuries induced by oxidative stress and are also involved in hypoxic postconditioning mediated neuroprotection,however,the role of FoxO in postconditioning mediated protection in the heart and in particular in high glucose condition is unknown.Methods:Rat heart-derived H9c2 cells were exposed to high glucose(HG) for 48 h,then subjected to hypoxia/reoxygenation(H/R,composed of 8 h of hypoxia followed by 12 h of reoxygenation) in the absence or presence of postconditioning with various concentrations of propofol(P-PostC) at the onset of reoxygenation.After having identified the optical concentration of propofol,H9c2 cells were subjected to H/R and P-PostC in the absence or presence of FoxO1 or FoxO3a gene silencing to explore their roles in P-PostC mediated protection against apoptotic and autophagic cell deaths under hyperglycemia.Results:The results showed that HG with or without H/R decreased cell viability,increased lactate dehydrogenase(LDH) leakage and the production of reactive oxygen species(ROS) in H9c2 cells,all of which were significantly reversed by propofol(P-PostC),especially at the concentration of 25 μmol/L(P25)(P<0.05,NC vs.HG;HG vs.HG+HR;HG+HR+P12.5 or HG+HR+P25 or HG+HR+P50 vs.HG+HR).Moreover,we found that propofol(P25) decreased H9c2 cells apoptosis and autophagy that were concomitant with increased FoxO1 and FoxO3a expression(P<0.05,HG+HR+P25 vs.HG+HR).The protective effects of propofol(P25) against H/R injury were reversed by silencing FoxO1 or FoxO3a(P<0.05,HG+HR+P25 vs.HG+HR+P25+siRNA-1 or HG+HR+P25+siRNA-5).Conclusions:It is concluded that propofol postconditioning attenuated H9c2 cardiac cells apoptosis and autophagy induced by H/R injury through upregulating FoxO1 and FoxO3a under hyperglycemia.

Artificial intelligence in liver ultrasound

Artificial intelligence(AI)is playing an increasingly important role in medicine,especially in the field of medical imaging.It can be used to diagnose diseases and predict certain statuses and possible events that may happen.Recently,more and more studies have confirmed the value of AI based on ultrasound in the evaluation of diffuse liver diseases and focal liver lesions.It can assess the severity of liver fibrosis and nonalcoholic fatty liver,differentially diagnose benign and malignant liver lesions,distinguish primary from secondary liver cancers,predict the curative effect of liver cancer treatment and recurrence after treatment,and predict microvascular invasion in hepatocellular carcinoma.The findings from these studies have great clinical application potential in the near future.The purpose of this review is to comprehensively introduce the current status and future perspectives of AI in liver ultrasound.

Automatic Satisfaction Analysis in Call Centers Considering Global Features of Emotion and Duration

Analysis of customers＇ satisfaction provides a guarantee to improve the service quality in call centers.In this paper,a novel satisfaction recognition framework is introduced to analyze the customers＇ satisfaction.In natural conversations,the interaction between a customer and its agent take place more than once.One of the difficulties insatisfaction analysis at call centers is that not all conversation turns exhibit customer satisfaction or dissatisfaction. To solve this problem,an intelligent system is proposed that utilizes acoustic features to recognize customers＇ emotion and utilizes the global features of emotion and duration to analyze the satisfaction. Experiments on real-call data show that the proposed system offers a significantly higher accuracy in analyzing the satisfaction than the baseline system. The average F value is improved to 0. 701 from 0. 664.

A Novel Two-Layer Model for Overall Quality Assessment of Multichannel Audio

With the development of multichannel audio systems, corresponding audio quality assessment techniques, especially the objective prediction models, have received increasing attention. Existing methods, such as PEAQ(Perceptual Evaluation of Audio Quality) recommended by ITU, usually lead to poor results when assessing multichannel audio, which have little correlation with subjective scores. In this paper, a novel two-layer model based on Multiple Linear Regression(MLR) and Neural Network(NN) is proposed. Through the first layer, two indicators of multichannel audio, Audio Quality Score(AQS) and Spatial Perception Score(SPS) are derived, and through the second layer the overall score is output. The final results show that this model can not only improve the correlation with the subjective test score by 30.7% and decrease the Root Mean Square Error(RMSE) by 44.6%, but also add two new indicators: AQS and SPS, which can help reflect the multichannel audio quality more clearly.

Tensor Completion for Recovering Multichannel Audio Signal with Missing Data

The quality of a multichannel audio signal may be reduced by missing data, which must be recovered before use. The data sets of multichannel audio can be quite large and have more than two axes of variation, such as channel, frame, and feature. To recover missing audio data, we propose a low-rank tensor completion method that is a high-order generalization of matrix completion. First, a multichannel audio signal with missing data is modeled by a three-order tensor. Next, tensor completion is formulated as a convex optimization problem by defining the trace norm of the tensor, and then an augmented Lagrange multiplier method is used for solving the constrained optimization problem. Finally, the missing data is replaced by alternating iteration with a tensor computation. Experiments were conducted to evaluate the effectiveness on data of a 5.1-channel audio signal. The results show that the proposed method outperforms state-of-the-art methods. Moreover, subjective listening tests with MUSHRA(Multiple Stimuli with Hidden Reference and Anchor) indicate that better audio effects were obtained by tensor completion.

Effects of rotational culture on morphology,nitric oxide production and cell cycle of endothelial cells

Devices for the rotational culture of cells and the study of biological reactions have been widely applied in tissue engineering.However,there are few reports exploring the effects of rotational culture on cell morphology,nitric oxide(NO)production,and cell cycle of the endothelial cells from human umbili-cal vein on the stent surface.This study focuses on these parameters after the cells are seeded on the stents.Results showed that covering of stents by endothelial cells was improved by rotational culture.NO produc-tion decreased within 24 h in both rotational and static culture groups.In addition,rotational culture signifi-cantly increased NO production by 37.9%at 36 h and 28.9%at 48 h compared with static culture.Flow cytometry showed that the cell cycle was not obviously influenced by rotational culture.Results indicate that rotational culture may be helpful for preparation of cell-seeded vascular grafts and intravascular stents,which are expected to be the most frequently implanted materials in the future.

First report of Alternaria alternata causing flower blight on Camellia sinensis in Hefei,China

Flowers are an essential organ for sexual reproduction of higher plants.Severe lesions along with flower blight on tea(Camellia sinensis)plants were observed in the experimental tea plantation located in Hefei(China).The pathogens isolated from diseased flowers matched the morphological peculiarity of Alternaria alternata.The species characteristics of A.alternata were further confirmed by both pathogenicity tests and multi-gene phylogenetic analyses by using internal transcribed spacer(ITS),glyceraldehyde-3-phosphate dehydrogenase(GAPDH)and betatubulin(TUB).The combined phylogeny analysis using sequences derived from the ITS,GAPDH and TUB showed that the isolated pathogens belong to the genus Alternaria.Pathogenicity tests conducted on healthy tea flowers and leaves manifested typical symptoms of flower blight while weaker symptoms of leaf spot,demonstrating the A.alternata isolates were the causal agents of flower blight disease on tea plants.This fungus is first reported as a pathogen causing flower blight on C.sinensis in this study.

Knowledge-embedded spatio-temporal analysis for euploidy embryos identification in couples with chromosomal rearrangements

Background:The goal of the assisted reproductive treatment is to transfer one euploid blastocyst and to help infertile women giving birth one healthy neonate.Some algorithms have been used to assess the ploidy status of embryos derived from couples with normal chromosome,who subjected to preimplantation genetic testing for aneuploidy(PGT-A)treatment.However,it is currently unknown whether artificial intelligence model can be used to assess the euploidy status of blastocyst derived from populations with chromosomal rearrangement.Methods:From February 2020 to May 2021,we collected the whole raw time-lapse videos at multiple focal planes from in vitro cultured embryos,the clinical information of couples,and the comprehensive chromosome screening results of those blastocysts that had received PGT treatment.Initially,we developed a novel deep learning model called the Attentive Multi-Focus Selection Network(AMSNet)to analyze time-lapse videos in real time and predict blastocyst formation.Building upon AMSNet,we integrated additional clinically predictive variables and created a second deep learning model,the Attentive Multi-Focus Video and Clinical Information Fusion Network(AMCFNet),to assess the euploidy status of embryos.The efficacy of the AMCFNet was further tested in embryos with parental chromosomal rearrangements.The receiver operating characteristic curve(ROC)was used to evaluate the superiority of the model.Results:A total of 4112 embryos with complete time-lapse videos were enrolled for the blastocyst formation prediction task,and 1422 qualified blastocysts received PGT-A(n=589)or PGT for chromosomal structural rearrangement(PGT-SR,n=833)were enrolled for the euploidy assessment task in this study.The AMSNet model using seven focal raw time-lapse videos has the best real-time accuracy.The real-time accuracy for AMSNet to predict blastocyst formation reached above 70%on the day 2 of embryo culture,and then increased to 80%on the day 4 of embryo culture.Combing with 4 clinical features of couples,the AUC of AMCFNet with 7 focal points increased to 0.729 in blastocysts derived from couples with chromosomal rearrangement.Conclusion:Integrating seven focal raw time-lapse images of embryos and parental clinical information,AMCFNet model have the capability of assessing euploidy status in blastocysts derived from couples with chromosomal rearrangement.

Aroma classification and flavor characterization of Streptococcus thermophilus fermented milk by HS-GC-IMS and HS-SPME-GC-TOF/MS

46 Streptococcus thermophilus strains,isolated from commercial starters cultures,were studied.The aroma of the fermented milk by these strains was evaluated by quantitative descriptive analysis(QDA).According to its major sensory attribute,the fermented milks were classified into milky-type,creamy-type,cheesy-type,fermented-type and miscellaneous-type groups.One representative sample of each group was analyzed by headspace-gas chromatography-ion mobility spectrometry(HS-GC-IMS)and headspace-solid phase microextraction-gas chromatography-time-of-flight mass spectrometry(HS-SPME-GC-TOF/MS)to describe their volatile compositions.48 and 72 volatile compounds were identified,respectively.The fingerprint analysis showed that each aroma type had specific volatile compounds.Six important differential volatile compounds including 2,3-butanedione,2,3-pentanedione,2-undecanone,octanoic acid,hexanoic acid and 2-hydroxy-3-pentanone were selected as key compounds by principal component analysis(PCA)and orthogonal partial least squares discriminant analysis(OPLS-DA),which allowed to discriminate the specific aroma types.These key compounds could be used as indicators to develop fermented milks with specific aroma and flavor features.

我国堆照医用同位素生产及应用现状与展望

医用同位素是指用于疾病诊断、治疗的放射性同位素,在恶性肿瘤、心脑血管等疾病诊疗方面具有不可替代的作用.由于我国医用同位素发展未得到应有重视,生产能力未充分发挥,且技术相对落后,监管科学性欠佳,导致医用同位素几乎全部依赖进口,时常短缺或断供,患者得不到及时诊疗无法受益于恶性肿瘤最佳治疗方案.医用同位素"卡脖子"问题已对国家公共卫生事业的健康发展形成明显制约,亟须建立我国医用同位素稳定自主供给体系.本文综述了近年来我国99Mo/99mTc、125,131I、89Sr、32P、177Lu、90Y、14C等重要堆照医用同位素的制备技术、生产及应用现状与发展趋势,分析了我国堆照医用同位素生产及应用存在的问题,提出了加快发展我国堆照医用同位素自主化生产及应用的发展措施及建议.

虚拟现实技术专利导航分析综述

专利导航是利用专利信息资源,引导和支撑技术与产业良性发展的基础性研究与推广工作.本文综述了由国家专利导航项目(高校)研究和推广中心完成的《虚拟现实相关技术专利导航分析报告》的部分成果,该报告对我国以及全球主要国家和地区在虚拟现实技术领域的专利申请进行了分析,从专利视角绘制了关键技术研发路线,导航相应的知识产权布局策略,对如何推动我国在新一轮技术竞争中降低对外部技术的依存度、培育创新主体的创新竞争力,以及确保国家技术安全提出了建议和措施.

压力-应变环对射血分数正常的心房颤动患者射频消融术前后左心室心肌做功的评价

目的应用左心室压力-应变环(PSL)量化评价左心室射血分数(LVEF)正常的心房颤动患者射频消融术前、术后的左心室心肌做功指数。方法这是一项回顾性研究。选取2020年1月至2020年12月于安徽医科大学第二附属医院就诊的LVEF正常的持续性心房颤动患者37例,所有患者均行心房颤动射频消融术。另选取同期37例健康者为对照组。所有心房颤动患者均在射频消融术前及术后3~6个月内行超声心动图检查。采集并获取心房颤动患者及对照组的常规超声心动图参数,以及左心室整体纵向应变(GLS)、整体做功指数(GWI)、整体有效功(GCW)、整体无效功(GWW)、整体做功效率(GWE),分析比较心房颤动患者术前、术后及对照组3组的常规超声心动图参数以及压力-应变参数的差异。结果心房颤动患者术前、术后及对照组LVEF比较,差异无统计学意义(P>0.05)。心房颤动组术前GLS、GWI、GCW及GWE低于对照组,GWW高于对照组,差异均有统计学意义(P均<0.05)。与术前比较,心房颤动组射频消融术后的GLS、GWI、GCW及GWE升高,GWW减低(P均<0.05);术后参数与对照组比较,GLS、GWI、GCW差异均无统计学意义(P均>0.05);但GWW高于对照组、GWE低于对照组,差异均有统计学意义(P均<0.05)。结论PSL可以定量评估LVEF正常的心房颤动患者术前及术后的左心室心肌做功改变,早期检测持续性心房颤动患者的心肌受损情况。早期行射频消融术恢复窦性心律,可以有效改善此类患者早期心肌受损。

下一代互联网互联设备关键技术专利导航研究综述

下一代互联网是全球各国推动科技产业革命和重塑国家长期竞争力的基础设施和先导领域,同样也是高科技密布、专利密集的战略性新兴产业领域,技术研发与创新竞争异常激烈.本文运用专利导航方法对全球下一代互联网互联设备相关技术进行了分析,通过对本导航领域多位技术专家的访谈,澄清和界定了下一代互联网互联设备关键技术的基本定义与范畴,从总体趋势、地域、核心申请人、核心发明人、专利强度、我国向国外申请专利,以及技术分支等方面分析了全球及我国下一代互联网互联设备关键技术的专利布局现状、竞争前沿和未来趋势,结合本导航领域国内外典型案例的总结,对研发创新和专利运用提出了相应的导航建议.

High shear stress induces atherosclerotic vulnerable plaque formation through angiogenesis

Rupture of atherosclerotic plaques causing thrombosis is the main cause of acute coronary syndrome and ischemic strokes.Inhibition of thrombosis is one of the important tasks developing biomedical materials such as intravascular stents and vascular grafts.Shear stress(SS)influences the formation and development of atherosclerosis.The current review focuses on the vulnerable plaques observed in the high shear stress(HSS)regions,which localizes at the proximal region of the plaque intruding into the lumen.The vascular outward remodelling occurs in the HSS region for vascular compensation and that angiogenesis is a critical factor for HSS which induces atherosclerotic vulnerable plaque formation.These results greatly challenge the established belief that low shear stress is important for expansive remodelling,which provides a new perspective for preventing the transition of stable plaques to high-risk atherosclerotic lesions.