Visible-light-induced,autopromoted nickel-catalyzed three-component arylsulfonation of 1,3-enynes and mechanistic insights

A light-induced, nickel-catalyzed three-component arylsulfonation of 1,3-enynes in the absence of photocatalyst is reported.This methodology exhibited mild conditions, broad scope and high efficiency, and its synthetic utility has been demonstrated by a concise total synthesis of sulfone-containing drug molecule. Detailed mechanistic studies indicated that this light induced nickel catalysis is autopromoted by in situ produced allene, which plays a key role as co-ligand in the photoactive excite...     

基于可见/近红外能量光谱的苹果褐腐病和水心鉴别

快速无损鉴别苹果内部品质的优劣是当前苹果行业亟待解决的一项重要课题.针对这一现状,提出了直接采用可见一近红外能量光谱对苹果褐腐病、水心鉴别的新方法,考察了不同判别分析方法对苹果类别判定的准确性.在能量光谱经MSC或者一阶导数处理后,分别采用了峰面积判别法(PADA)、主成分分析判别法(PCADA)、偏最小二乘判别法(PLSDA)建立判别模型.结果显示,三种方法对褐腐病苹果判别正确率都为100%;对水心苹果分别是79.2%,95.0%和96.7%;对正常苹果分别是88.6%,98.2%和98.8%.其中,PCADA和PLSDA明显优于PADA,而PLSDA总判别率最高,达到98.1%,其建模标准差RMSEC为0.449,预测标准差RMSEP为0.392,说明可见一近红外能量光谱结合化学计量学算法可以快速、无损鉴别苹果褐腐病和水心.     

垃圾填埋渗滤液溶解性有机物组分的光谱学特性研究

选取3个不同填埋年限的渗滤液样品,以Leenheer的分组方法为基础,采用XAD-8树脂将渗滤液中的溶解性有机物(DOM)按极性和电荷特性分为结构较为均一的不同组分,用荧光光谱和紫外光谱对其中3个组分进行分析。荧光光谱分析表明,填埋初期,疏水酸性组分(HOA)、疏水中性组分(HON)和亲水性组分(HIM)均以类蛋白物质为主,随着填埋年限增加,其分子复杂化程度增强;其中HOA组分分子量最大、复杂程度最高,同时芳烃化合物的含量也最高,HON居中,HIM组分最小。紫外光谱分析表明,HOA和HON组分芳香环上的取代基均以羰基、羧基、羟基为主;而HIM组分则以脂肪链为主,同时芳香烃化合物含量较低。研究结果表明,随着填埋年限的增加,三种组分的复杂化程度均呈上升趋势。     

Preparation of Silica Aerogel/Resin Composites and Their Application in Dental Restorative Materials

As the most advanced aerogel material, silica aerogel has had transformative industrial impacts. However, the use of silica aerogel is currently limited to the field of thermal insulation materials, so it is urgent to expand its application into other fields. In this work, silica aerogel/resin composites were successfully prepared by combining silica aerogel with a resin matrix for dental restoration. The applications of this material in the field of dental restoration, as well as its performance, are discussed in depth. It was demonstrated that, when the ratio of the resin matrix Bis-GMA to TEGDMA was 1:1, and the content of silica aerogel with 50 μm particle size was 12.5%, the composite achieved excellent mechanical properties. The flexural strength of the silica aerogel/resin composite reached 62.9546 MPa, which was more than five times that of the pure resin. Due to the presence of the silica aerogel, the composite also demonstrated outstanding antibacterial capabilities, meeting the demand for antimicrobial properties in dental materials. This work successfully investigated the prospect of using commercially available silica aerogels in dental restorative materials; we provide an easy method for using silica aerogels as dental restorative materials, as well as a reference for their application in the field of biomedical materials.     

Py-GC/MS分析技术与其在烟用中草药添加剂中的应用

通过热裂解实验,可以更加深入地了解卷烟燃吸过程中各个燃烧条件和整个烟气化学的关系,还可对不同温度下的裂解产物和作用机理进行研究。本文综述了裂解-气相色谱/质谱法在烟用中草药添加剂研究中的应用。     

A study on Al2O3 passivation in GaN MOS-HEMT by pulsed stress

This paper studies systematically the drain current collapse in AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors （MOS-HEMTs） by applying pulsed stress to the device. Low-temperature layer of Al2O3 ultrathin film used as both gate dielectric and surface passivation layer was deposited by atomic layer deposition （ALD）. For HEMT, gate turn-on pulses induced large current collapse. However, for MOS-HEMT, no significant current collapse was found in the gate turn-on pulsing mode with different pulse widths, indicating the good passivation effect of ALD Al2O3. A small increase in Id in the drain pulsing mode is due to the relieving of self-heating effect. The comparison of synchronously dynamic pulsed Id - Vds characteristics of HEMT and MOS-HEMT further demonstrated the good passivation effect of ALD Al2O3.     

Performance of La2O3/InAlN/GaN metal—oxide—semiconductor high electron mobility transistors

We report on the performance of La2O3/InAlN/GaN metal-oxide-semiconductor high electron mobility transistors(MOSHEMTs) and InAlN/GaN high electron mobility transistors(HEMTs).The MOSHEMT presents a maximum drain current of 961 mA/mm at Vgs = 4 V and a maximum transconductance of 130 mS/mm compared with 710 mA/mm at Vgs = 1 V and 131 mS/mm for the HEMT device,while the gate leakage current in the reverse direction could be reduced by four orders of magnitude.Compared with the HEMT device of a similar geometry,MOSHEMT presents a large gate voltage swing and negligible current collapse.     

红光InAlAs量子点的结构和光学性质

利用ＭＢＥ方法在（００１）衬底上成功地生长密度大、尺寸小、发红光的ＩｎＡｌＡｓ／ＡｌＧａＡｓ量子点结构。通过原子力显微镜观察表明,ＩｎＡｌＡｓ量子的密度和大小都随覆盖厚度的增加而增大;发现Ａｌ原子的表面迁移率决定ＩｎＡｌＡｓ量子点的形貌,光荧光谱证实了量子点的发光峰值在红光范围,并结合形貌的统计得到了量子点的发光峰展宽主要昌受量子点的横向尺寸影响。     

求解Euler方程的区域分解方法与并行算法

将复杂形状区域划分成多块子区域,研究发展了一种多块区域之间迎风守恒型的内边界耦合方法,实现相邻子区域解的光滑过渡,使多区耦合得到总体流场的数值解。对二维翼型跨音速流动和圆弧形隆起物超音速流动等进行了分区数值计算,并将计算结果与单区计算结果和实验结果作了比较。并行分区计算引入"先进先出"的同步控制等待机制,实现了高效率并行计算,还分析了影响并行效率的主要因素。     

CaMoO4：Eu3+,Bi3+,Li+红色荧光粉的共沉淀制备与表征

采用共沉淀法合成了红色荧光粉Ca_0.75MoO₄：Eu_0.25³⁺、Ca_0.75MoO₄：Eu_0.25-x³⁺,Bi_x³⁺及Ca_0.5MoO₄：Eu_0.25-2x³⁺, Bi_x³⁺,Li_0.25+x⁺,并采用X射线衍射(XRD)、拉曼光谱,扫描电镜(SEM)和荧光光谱(PL)测定分析了其结构形貌特征及发光性能。结果表明：制备的CaMoO₄：Eu³⁺,Bi³⁺,Li⁺红色荧光粉为白钨矿结构,颗粒尺寸约为0.5~1 μm。掺杂Bi³⁺的Ca_0.75MoO₄：Eu_0.25-x³⁺,Bi_x³⁺的相对发光强度明显高于未掺Bi³⁺的Ca_0.75MoO₄：Eu_0.25³⁺荧光粉。Bi³⁺离子的掺杂将吸收来的能量传递给激活离子Eu³⁺,起到了能量传递的作用。当Bi³⁺掺杂量为x=0.005时,在395 nm激发下,主发射峰在616 nm处的相对发光强度最大,但掺杂浓度过高时会出现浓度猝灭现象。另外,电荷补偿剂的掺入能够解决材料中因同晶取代引起的电荷不平衡的问题,以Li⁺作电荷补偿剂、Eu³⁺和 Bi³⁺共掺合成的Ca_0.5MoO₄：Eu³⁺_0.23,Bi_0.01³⁺,Li⁺_0.26红色荧光粉的发光性能强于Ca_0.75MoO₄：Eu_0.25³⁺、Ca_0.5MoO₄：Eu_0.25³⁺, Li_0.25⁺及Ca_0.75MoO₄：Eu_0.24³⁺,Bi_0.01³⁺。