TC4钛合金-316L不锈钢真空钎焊接头组织与性能研究

为了实现TC4钛合金和316L不锈钢的良好连接,以Ti-Zr-Hf-Cu-Ni非晶合金作为钎料,研究了钎焊温度对接头组织与性能的影响。结果表明,在960 ℃/10 min的焊接工艺参数下,取得了高达205 MPa的接头剪切强度。接头由316L/扩散层Ⅰ/焊缝中心区域Ⅱ/扩散层Ⅲ/TC4五个部分构成,具体的组织构成为316L/γ-Fe+σ+α-Fe+τ+Fe2Ti+FeTi/β-Ti+(Ti,Zr,Hf)2(Cu,Ni)/β-Ti/TC4。靠近316L一侧的扩散层Ⅰ由Fe-Ti等脆硬化合物相构成,为接头薄弱区域,断裂位置位于该区域。     

Influence of Sensitive Parameters on Pressure Wave Velocity of Gas Drilling Fluid

Chemistry and Technology of Fuels and Oils - In this paper, the authors have simulated pressure wave propagation in a closed system, considering the virtual mass force on the interphase border, the...     

Quality changes of salmon (Oncorhynchus gorbuscha) muscle during thermal processing

ABSTRACT:  The objective of this study was to investigate quality changes of salmon fillet muscle during thermal sterilization processes. Small samples (D 30 mm × H 6 mm) from the central dorsal region were heated in an oil bath at 121.1 °C for periods varying from 5 to 120 min. The quality variations along the longitudinal axis of salmon fillets (raw and heated) were examined. The quality properties studied included shear force, color, cook loss, and shrinkage. To minimize the influence of the heterogeneity of the salmon muscle, a multiple thin blade texture device was developed for shear force measurement and a computer vision system was used to facilitate accurate measurements of color and shrinkage. The red muscle was firmer than the white muscle in the raw but not in heated samples. Muscle from the central dorsal region had a lower cook loss and less shrinkage than samples from either the anterior or posterior region following heating. The greatest change in quality occurred within the 1st 10 min of heating at 121.1 °C. Shear force measurements following heating indicated 2 peaks, one corresponding to 5 min and the second for 60 min processing at 121.1 °C. Possible mechanisms were discussed.     

Exosome-mimicking nanovesicles derived from efficacy-potentiated stem cell membrane and secretome for regeneration of injured tissue

Translation of exosome-based therapies to pharmaceutical use is hindered by difficulties in large-scale and cost-effective production of clinical-grade exosomes.The rational design of nanovesicles that mimic the functionalities and physicochemical properties of exosomes may circumvent these issues.In this study,membranes and secretome from efficacy-potentiated mesenchymal stem cells(MSCs)were developed into size-controllable nanovesicles(Meseomes).MSCs were primed with interferon-y(IFNy)and tumor necrosis factor-a(TNFa),harvested,and exosome-mimicking Meseomes were subsequently synthesized via one-step extrusion.Meseomes demonstrated significant enhancement of pro-angiogenic,pro-proliferative,antiinflammatory,and anti-fibrotic effects on endothelial cells,macrophages,and hepatic stellate cells in vitro.Meseomes from primed MSCs benefited from an enrichment of bioactive and therapeutic molecules compared to nanovesicles from unprimed MSCs,as validated by liquid chromatography-mass spectrometry(LC-MS)proteomic analysis.Systemic administration of Meseomes to acute liver injury models resulted in the recovery of liver function,attenuated tissue necrosis.Further assessment of locally administered Meseomes in acute hindlimb ischemia models resulted in the salvage of the majority of the ischemic hindlimb(>80%),which was due to enhanced angiogenesis and M2 macrophage polarization.The versatility and therapeutic efficacy of our developed acellular Meseomes offer an appealing alternative to traditional cell or exosome therapies for regenerative and translational medicine.     

Biological Characteristics of Verticillium dahliae MAT1-1 and MAT1-2 Strains

Verticillium dahliae is a soil-borne plant pathogenic fungus that causes Verticillium wilt on hundreds of dicotyledonous plant species. V. dahliae is considered an asexually (clonal) reproducing fungus, although both mating type idiomorphs (MAT1-1 and MAT1-2) are present, and is heterothallic. Most of the available information on V. dahliae strains, including their biology, pathology, and genomics comes from studies on isolates with the MAT1-2 idiomorph, and thus little information is available on the MAT1-1 V. dahliae strains in the literature. We therefore evaluated the growth responses of MAT1-1 and MAT1-2 V. dahliae strains to various stimuli. Growth rates and melanin production in response to increased temperature, alkaline pH, light, and H₂O₂ stress were higher in the MAT1-2 strains than in the MAT1-1 strains. In addition, the MAT1-2 strains showed an enhanced ability to degrade complex polysaccharides, especially starch, pectin, and cellulose. Furthermore, several MAT1-2 strains from both potato and sunflower showed increased virulence on their original hosts, relative to their MAT1-1 counterparts. Thus, compared to MAT1-1 strains, MAT1-2 strains derive their potentially greater fitness from an increased capacity to adapt to their environment and exhibit higher virulence. These competitive advantages might explain the current abundance of MAT1-2 strains relative to MAT1-1 strains in the agricultural and sylvicultural ecosystems, and this study provides the baseline information on the two mating idiomorphs to study sexual reproduction in V. dahliae under natural and laboratory conditions.     

A novel multifunctional phosphorous and nitrogenous reactive flame retardant toward epoxy resins by one-pot method

Epoxy resin (EP) has attracted considerable attention in packaging, electronic devices, aerospace, and coatings fields owing to its remarkable chemical and physical performance. However, the inherent flammable performance and unfavorable brittle nature seriously restricted its application in sophisticated industry. Herein, an efficient reactive 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based flame retardant (DB-DAD) was prepared by a facile “one-pot” method. Due to their synergistic gas-phase and solid-phase flame-retardant effects, DB-DAD modified EP composites (EP/DB-DAD composite) easily achieved UL-94 V-0 ratings, and an EP/DB-DAD composite with a 0.32 wt% phosphorus content had an excellent (30.2%) limiting oxygen index. In addition, the amounts of heat and smoke decreased by 28.1% and 24.8%, respectively. Due to the introduction of long and flexible aliphatic chains, the EP/DB-DAD composites exhibited satisfactory mechanical properties, the flexural and tensile toughness of EP/6% DB-DAD were 82.5% and 62.2% higher than those of neat EP, respectively. Furthermore, EP/DB-DAD composite showed good transparency (>85%) and favorable UV shielding performance. The EP/DB-DAD composite with good comprehensive performance is extremely promising to accelerate EP application in high-tech industries.     

隐私保护下的车辆轨迹联邦嵌入学习与聚类

智能网联汽车的高维轨迹数据被广泛用于从车辆的行驶轨迹中发现不同运动模式,从而降低交通风险、提高通行效率. 然而,数据利用过程中的隐私问题日益受到关注,如何在隐私保护的前提下进行算法的研究和应用是当前面临的一大挑战. 针对车辆轨迹数据分散在不同持有方且出于隐私保护无法共享数据的背景,利用差分隐私联邦学习框架来构建序列自编码网络提取轨迹序列的低维表示,并进一步利用轨迹的低维空间向量来发现不同时段下车辆的频繁路线. 提出的框架既通过本地训练避免了用户隐私数据的分享,又能通过高斯差分隐私机制防止模型信息的泄露. 该框架在真实的轨迹数据集上进行了验证,利用LSTM自编码作为嵌入学习网络,与非联邦、非差分加密的模型进行了对比分析,最后对三种得到的轨迹嵌入通过聚类分析发现该框架下学习的模型在充分尊重了隐私保护的前提下,仍然能够找出有效的频繁轨迹.     

创新组织管理 促进项目增效——旅大油田群建设工程项目组织管理创新实践

科学合理地处理成本、进度和质量三大主要控制目标之间的关系,使项目整体效益最大化,是工程项目管理工作的难点和重点。旅大油田群建设工程项目组从创新组织管理入手,更新管理理念、更新管理模式、更新管理方法,促使项目成本、进度、质量三者之间相互促进、协调发展,创造了多项行业纪录,取得了好的社会效益和经济效益。文中对该项目组在创新组织管理方面的探索进行了总结。     

平板显示器用塑料基片

介绍了具有多层涂膜的塑料基片,它们对于潮气和氧具有足够的不可渗透性,可用于对潮气灵敏的显示器,譬如LCD,小分子有机半导体发光二极管显示器和聚合物半导体发光二极管显示器.     

Oxidative stress: an important phenomenon with pathogenetic significance in the progression of acute pancreatitis

BACKGROUND: Reactive oxygen species and related oxidative damage have been implicated in the initiation of acute pancreatitis. Changes in these parameters during disease progression merit further investigation. AIMS: To evaluate changes and the clinical relevance of superoxide radicals, endogenous antioxidants, and lipid peroxidation during the course of acute pancreatitis. PATIENTS AND METHODS: Superoxide radicals (measured as lucigenin amplified chemiluminescence), ascorbic acid, dehydroascorbic acid, alpha tocopherol, and lipid peroxidation (measured as thiobarbiturate reactive substances) were analysed in blood samples from 56 healthy subjects, 30 patients with mild acute pancreatitis, and 23 patients with severe acute pancreatitis. The association with grades of disease severity was analysed. Measurements were repeated one and two weeks after onset of pancreatitis. RESULTS: In the blood from patients with acute pancreatitis, there were increased levels of the superoxide radical as well as lipid peroxides. There was notable depletion of ascorbic acid and an increased fraction of dehydroascorbic acid. Changes in alpha tocopherol were not great except in one case with poor prognosis. Differences between severe and mild acute pancreatitis were significant (p < 0.01). Variable but significant correlations with disease severity scores were found for most of these markers. The normalisation of these indexes postdated clinical recovery one or two weeks after onset of disease. CONCLUSIONS: Heightened oxidative stress appears early in the course of acute pancreatitis and lasts longer than the clinical manifestations. The dependence of disease severity on the imbalance between oxidants and natural defences suggests that oxidative stress may have a pivotal role in the progression of pancreatitis and may provide a target for treatment.