新型功能碳材料的高压截获

高性能功能材料在诸多领域具有广泛的应用前景,是人们一直关注的研究热点。高压可以有效地改变物质的原子间距和成键方式,是获得新型功能材料的重要途径。在碳材料的高压研究中,许多有趣的功能碳材料,如光学透明碳、高强度弹性碳和超硬非晶碳等,已经通过不同的碳前驱体合成。本文简要介绍了作者近年来在低维碳基纳米复合材料高压研究中取得的进展,基于设计的不同低维碳前驱体,高压下截获了具有超硬特性、新型压致共价聚合及发光增强的碳材料。     

An efficient projection-type method for monotone variational inequalities in Hilbert spaces

Numerical Algorithms - We consider the monotone variational inequality problem in a Hilbert space and describe a projection-type method with inertial terms under the following properties: (a) The...     

AlGaN基宽禁带半导体光电材料与器件

AlGaN基材料是带隙可调的直接带隙宽禁带半导体材料,是制备紫外(UV)光电子器件的理想材料.经过数十年的研究,目前已经在异质衬底外延生长AlGaN基材料、高效掺杂等方面取得了巨大进展.以此为基础,AlGaN基紫外光电器件制备领域也得到长足发展.在本综述中,主要介绍了高质量AlGaN基材料的MOCVD外延生长方法、掺杂方法以及近年来在紫外发光、紫外探测器件方面取得的进展.     

基于旋转变换和鲁棒主成分分析的车牌校正方法

本文研究了受到非高斯噪声污染及边框信息不完整的车牌图像校正的问题.利用鲁棒主成分分析与旋转变换结合的方法,获得了更具普适性的车牌矫正方法.并通过与主成分分析法、旋转投影法的矫正结果相比较,推广了本文方法具有更好的鲁棒性和普适性的结果.     

Scalable and Robust Bio-inspired Organogel Coating by Spraying Method Towards Dynamic Anti-scaling

Scaling usually causes serious problems in daily life and industrial production. Currently, developing passive anti-scaling coatings has shown promises to overcome this problem. In this work, we fabricated a scalable and robust bio-inspired organogel(BIO) coating, showing dynamic scale resistance in the oil/brine mixture. The oil layer of the BIO coating was utilized as a barrier to inhibit scale nucleation and reduce scale adhesion. The mechanical strength of the coating was optimized by regulating nanoparticle contents. Moreover, the universality of scale resistance was demonstrated by varying the types of nanoparticles, oils and scales. Compared with commercial pipeline materials, such as copper, this BIO coating significantly reduces scale deposition after 240-h scaling test(ca. 93% reduction). Therefore, this study designs scalable and robust organogel coatings for sustainable scale resistance, which may be used for practical application in oil production.     

Electrospinning of Biomaterials for Vascular Regeneration

Cardiovascular diseases have been the leading cause of morbidity and mortality in the world recently. With the growing aging population accompanied by chronic diseases, such as uremia and diabetes, there is an increasing clinical demand for vascular grafts with proper performance. Although some achievements have been made in the development of tissue-engineered vascular grafts composed of natural and synthetic polymeric materials or decellularized vessels, clinical applications with a diameter of less than 6 mm are still principally derived from autografts, such as autologous saphenous veins. Many challenges remain in anti-thrombosis, rapid endothelialization, modulating the inflammatory response and inhibition of intimal hyperplasia and calcification. In the review, recent progress in the electrospinning of biodegradable polymers for vascular regeneration are summarized, especially from the view of biomechanical factors. Hybrid vascular grafts consisting of natural and synthetic polymers with multicomponent, di-or tri-layers are focused in order to provide novel experiences in biomaterials for applications in this field.     

Design and Construction of 3D Porous Na3V2(PO4)3/C as High Performance Cathode for Sodium Ion Batteries

An easy and delicate approach using cheap carbon source as conductive materials to construct 3D sequential porous structural Na3V2(PO4)3/C(NVP/C)with high performance for cathode materials of sodium ion battery is highly desired.In this paper,the NVP/C with 3D sequential porous structure is constructed by a delicate approach named as“cooking porridge”including evaporation and calcination stages.Especially,during evaporation,the viscosity of NVP/C precursor is optimized by controlling the adding quantity of citric acid,thus leading to a 3D sequential porous structure with a high specific surface area.Furthermore,the NVP/C with a 3D sequential porous structure enables the electrolyte to interior easily,providing more active sites for redox reaction and shortening the diffusion path of electron and sodium ion.Therefore,benefited from its unique structure,as cathode material of sodium ion batteries,the 3D sequential porous structural NVP/C exhibits high specific capacities(115.7,88.9 and 74.4 mA·h/g at current rates of 1,20 and 50 C,respectively)and excellent cycling stability(107.5 and 80.4 mA·h/g are remained at a current density of 1 C after 500 cycles and at a current density of 20 C after 2200 cycles,respectively).     

带Beddington-DeAngelis功能反应和Levy噪声的随机捕食-被捕食系统的渐近性质

本文考虑了一类带Beddington-DeAngelis功能反应和Levy噪声的随机捕食-被捕食系统.利用构建Lyapunov函数和停时技巧给出了具有正初始值系统的正解的存在唯一性.得到了系统正解的矩的渐近有界性.利用带跳的指数鞅不等式得到了解增长速度的上界估计.最后,给出了物种灭绝的充分条件.     

YVO_4∶Eu~(3+)@SiO_2核壳结构纳米复合材料的合成与表征

用沉淀法制备了尺寸约为8 nm的YVO4∶Eu3+纳米粒子,然后用反相微乳液法在YVO4∶Eu3+纳米粒子的表面包覆了一层Si O2壳。利用XRD、TEM、UV-Vis吸收光谱和光致发光光谱对合成的样品进行了表征。得到的复合物具有较好的核壳结构,通过改变硅酸四乙酯的用量可以改变Si O2壳的厚度。研究了Si O2壳对YVO4∶Eu3+发光性质的影响,结果表明:包覆和未包覆的样品在紫外光激发下都有Eu3+的特征发射;随着Si O2壳厚度的增加,发光强度和量子效率越来越低,Eu3+格位对称性越来越高。     

烷烃/正庚烷和醇/正庚烷二元燃料低温着火特性的模拟研究

二元燃料燃烧技术作为一种应用替代能源的技术已经被广泛应用,为了深入地理解天然气、液化石油气和醇类等被引燃燃料对柴油低温着火的推迟影响,本文对二元燃料低温着火过程进行了模拟研究。结果表明,在初始温度小于1000 K时,被引燃燃料推迟正庚烷着火的能力由高到低的顺序为:乙烷丙烷正丁烷正戊烷正己烷,从正戊烷开始,被引燃燃料对正庚烷着火的抑制作用开始消失。甲醇和乙醇几乎没有低温反应活性,它们将活泼的OH转化为了稳定的H_2O_2;醛类和烯醇的生成反应是醇类燃料推迟正庚烷着火能力强于对应烷烃燃料的原因。