Research Progress of Metal Material Liquid Forming Technology

随着汽车工业的迅速发展以及市场竞争对铸件质量要求的提高,推动了金属材料液态成型技术发展。从20世纪70年代压铸技术的广泛运用,到90年代挤压铸造技术的不断完善,随后挤压压铸技术不断创新,使液态成型技术向多学科渗透融合发展,应用领域不断拓展,铸件用量逐年上升。重点介绍了压铸、挤压铸造、挤压压铸这三种重要的成型技术发展以及取得的最新成果。With the rapid development of auto industry and the market competition on the increase of the requirement of the casting quality,the development of metal material liquid forming technology was promoted.From the extensive use of the die casting technology in the nineteen seventies to constant maturity of the 90's the squeeze casting technology,and then the continuous innovation of squeezing die casting,the liquid forming technology for multidisciplinary permeated and developed,application area continued to expand,and casting quantities increased year by year.The development and the latest achievements of three kinds of important forming technologies(die casting,squeezing casting and squeezing die casting) were mainly introduced.贵州省(贵阳市)工业攻关项目(黔科合GY字[2012]3004;筑科合同[2012101]2-13号

Successive modification of polydentate complexes gives access to planar carbon-and nitrogen-based ligands

以碳和氮为键合原子的多齿螯合物是配合物家族中非常重要的一类。具有更高齿数的平面构型NC螯合物实例相对较少，代表性的例子为四齿金属碳卟啉类化合物，这类螯合物以其独特的结构和丰富的物理化学性质引起广泛关注。然而平面五齿、六齿的NC螯合物由于几何构型“拥挤”导致合成难度高，该工作从含三元环内金属卡宾结构的CCCC型碳龙配合物出发，利用经典有机反应（炔烃对金属卡宾的插入反应），成功地实现了CCCCN/NCCCN型平面五齿螯合物的合成。这一研究为高配位型螯合物的合成提供了新思路并为平面五齿螯合物家族添加新成员。特别是，这些高配位型螯合物在可见光和近红外区域均有较好的吸收，表现出良好的光声成像、光热转换及声动力学性能。 该研究工作在张弘教授指导下完成，第一作者为iChEM博士后周小茜。该工作充分体现了多学科协同研究优势：相关化合物的合成、表征及理论计算工作由周小茜博士完成；声动力学性能研究由厦门大学公共卫生学院庞鑫博士及刘刚教授完成；光声成像研究由厦门大学公共卫生学院聂立铭教授完成。iChEM fellow卓庆德博士、博士生卓凯玥、陈志昕参与了部分实验工作。夏海平教授、香港科技大学林振阳教授和南京大学朱从青教授对研究工作给予了大力支持。【Abstract】Polydentate complexes containing combinations of nitrogen and carbon (N and C) ligating atoms are among the most fundamental and ubiquitous molecules in coordination chemistry, yet the formation of such complexes with planar high-coordinate N/C sites remains challenging. Herein, we demonstrate an efficient route to access related complexes with tetradentate CCCN and pentadentate CCCCN and NCCCN cores by successive modification of the coordinating atoms in complexes with a CCCC core. Combined experimental and computational studies reveal that the rich reactivity of metal-carbon bonds and the inherent aromaticity of the metallacyclic skeletons play key roles in these transformations. This strategy addresses the paucity of synthetic approaches to mixed N/C planar pentadentate chelating species and provides valuable insights into the synthesis of carbon-based high-coordinate complexes. Furthermore, the resulting complexes are the examples of organometallic species with combined photoacoustic, photothermal, and sonodynamic properties, which makes them promising for application in related areas.This research was supported by the National Natural Science Foundation of China (Nos. 21572185, 21561162001, and 81571744), the Research Grants Council of Hong Kong (N_HKUST603/15), the Excellent Youth Foundation of Fujian Scientific Committee (2018J06024), and the Fundamental Research Funds for the Central Universities (20720170065).该工作得到国家自然科学基金委、香港研究资助局、福建省自然科学基金、厦门大学校长基金的资助

Trisomy 21-induced Dysregulation of Microglial Homeostasis in Alzheimer’s Brains is Mediated by USP25

阿尔茨海默病（Alzheimer’s disease, AD）是一种最为常见的与记忆、认知能力退化相关的渐进性神经退行性疾病。唐氏综合征（Down’s syndrome, DS）是早发型阿尔茨海默病的一个重要风险因素，作为最常见的智力障碍遗传疾病，厦门大学医学院神经科学研究所王鑫教授团队揭示了治疗阿尔茨海默病和唐氏综合征新的治疗靶点，并且在小鼠模型上利用USP25小分子抑制剂成功地改善了阿尔茨海默病小鼠的认知功能，缓解了神经退行性病变的病理进程。该研究工作由王鑫教授指导完成，厦门大学医学院助理教授郑秋阳和博士生李桂林完成主要实验工作，王世华、朱琳、高月、邓青芳、张洪峰、张丽珊、吴美玲、狄安洁参与了部分研究工作。厦门大学医学院许华曦、赵颖俊和孙灏教授在研究过程中给予大力帮助和支持，清华大学董晨教授提供了Usp25基因敲除小鼠，厦门大学附属妇女儿童医院周裕林教授和郑良楷博士帮助收集了脑组织样品。Down syndrome (DS), caused by trisomy of chromosome 21, is the most significant risk factor for early-onset Alzheimer’s disease (AD); however, underlying mechanisms linking DS and AD remain unclear. Here, we show that triplication of homologous chromosome 21 genes aggravates neuroinflammation in combined murine DS-AD models. Overexpression of USP25, a deubiquitinating enzyme encoded by chromosome 21, results in microglial activation and induces synaptic and cognitive deficits, whereas genetic ablation of Usp25 reduces neuroinflammation and rescues synaptic and cognitive function in 5×FAD mice. Mechanistically, USP25 deficiency attenuates microglia-mediated proinflammatory cytokine overproduction and synapse elimination. Inhibition of USP25 reestablishes homeostatic microglial signatures and restores synaptic and cognitive function in 5×FAD mice. In summary, we demonstrate an unprecedented role for trisomy 21 and pathogenic effects associated with microgliosis as a result of the increased USP25 dosage, implicating USP25 as a therapeutic target for neuroinflammation in DS and AD.This work was supported by the National Natural Science Foundation of China (31871077, 81822014, and 81571176 to X.W.; 81701130 to Q.Z.), the National Key R&D Program of China (2016YFC1305900 to X.W.), the Natural Science Foundation of Fujian Province of China (2017J06021 to X.W.), the Fundamental Research Funds for the Chinese Central Universities (20720150061 to X.W.), and the BrightFocus Foundation (A2018214F to Yingjun Zhao). 该研究工作得到国家重点研发计划项目、国家自然科学基金、福建省自然科学基金、厦门大学校长基金的资助和支持

PINT业务在软交换网络中的实现

文章介绍了智能网与Internet互通的原理,以及PINT（PSTN Internet iNTerworking）业务的基本概念和网络结构,并对PINT协议进行了分析。同时给出了智能网与Internet互联的模型,并结合点击拨号业务讨论了其具体的实现方式。最后讨论了互联时的安全问题

氨燃料吸气式变循环发动机性能分析

针对飞行马赫数0～10的宽域飞行器对吸气式动力的需求，本文提出了一种以氨为燃料和冷却剂的宽域吸气式变循环发动机，其工作模态可有三种：涡轮模态，预冷模态和冲压模态。本文首先通过对该发动机各模态热力循环过程进行建模，计算得到发动机比推力、比冲和总效率等性能参数，初步验证了其在马赫数0～10范围内工作的可行性；然后，选取甲烷和正癸烷为低温低密度和煤油类碳氢燃料的典型代表，对比了各模态下氨与碳氢燃料发动机的性能差异。结果表明，由于氨突出的当量总热沉和当量热值，飞行马赫数3～5的预冷模态发动机性能各指标均优于碳氢燃料。在涡轮模态和冲压模态下，氨燃料发动机比冲较低，但比推力和总效率优于碳氢燃料；最后，对比分析了各类燃料马赫数0～10宽域工作特性，发现氨预冷可以显著提升发动机比推力，特别在高马赫数范围，再生冷却通道内氨可发生裂解反应大量吸热并分解为氢气和氮气，会进一步提升发动机比推力和比冲，且不会堵塞冷却通道，因此可胜任飞行马赫数0-10的宽范围飞行需求。而煤油类碳氢燃料受限于比推力低和裂解结焦问题，最高工作马赫数难以超过8。综上所述，本文提出的氨燃料吸气式变循环发动机，当量冷却能力强且比推力高，适合用于二级入轨飞行器的一级动力、高马赫数宽域吸气式飞行以及未来高超声速民航等场景

Target state estimation based on particle filter

在粒子滤波框架下,提出了1种采用当前统计模型的状态估计方法,并对模型的噪声分配系数提出了1种合理的离散化表示。实验验证了方法自身的有效性,与在卡尔曼滤波框架下采用当前统计模型的状态估计方法进行了比较,结果表明本方法不仅可以逼近最优估计,而且对于运动目标的机动性具有较好的鲁棒性,提升了对机动目标的状态估计性能。 &nbsp

Crystal nucleation and metastable bcc phase in charged colloids: A molecular dynamics study

The dynamic process of homogenous nucleation in charged colloids is investigated by brute-force molecular dynamics simulation. To check if the liquid-solid transition will pass through metastable bcc, simulations are performed at the state points that definitely lie in the phase region of thermo-dynamically stable fcc. The simulation results confirm that, in all of these cases, the preordered precursors, acting as the seeds of nucleation, always have predominant bcc symmetry consistent with Ostwald&#39;s step rule and the Alexander-McTague mechanism. However, the polymorph selection is not straightforward because the crystal structures formed are not often determined by the symmetry of intermediate precursors but have different characters under different state points. The region of the state point where bcc crystal structures of large enough size are formed during crystallization is narrow, which gives a reasonable explanation as to why the metastable bcc phase in charged colloidal suspensions is rarely detected in macroscopic experiments. Published by AIP Publishing.</p

The Effect of Phase Difference of Linear Signal and the Control Signal on the Periodical Mean Force

自旋导弹的姿态通常采用单通道控制方法。介绍了该控制方法所应用的周期平均力形成原因,以及其大小和方向的确定方法; 阐述了该控制方法中使用的线性化控制方法; 分析了线性化信号和控制信号之间的相位差对周期平均力的影响; 得出了周期平均力的大小和方向均随相位差周期性的变化,且变化周期为&pi;的规律,并且得到了精确的变化曲线,周期平均力的最大的偏差角为8.8&deg;,幅度变化最大时为无相位差时的槡3倍,这些结论为更加合理的控制导弹提供了重要的理论依据

亚硝酸钠/盐酸催化氧气氧化碘化芳烃、醚、酚化合物

以廉价易得的盐酸/亚硝酸钠为催化剂,碘为碘化试剂,通过分子氧,氧化碘化芳烃、醚、酚的活泼芳香底物,发展了温和条件下高效碘化方法。以苯甲醚为模型底物,系统考察了影响反应的因素,确定的最佳反应条件为：20℃氧气条件下,1,2-二氯乙烷（DCE）为溶剂,n（苯甲醚）∶n（碘）∶n（亚硝酸钠）∶n（HC l）=1∶0.515∶0.05∶0.1。该方法碘原子经济性好,催化剂廉价易得,反应时间大为缩短,选择性好、转化率高,副产物仅为水,容易处理,绿色环保、易于工业化;通过反应机理验证实验,提出了可能的催化循环机理