Crystal structure and fluorescent properties of a 2D cadmium coordination polymer

A new 2D cadmium(II) coordination polymer {[Cd(MBD)(L)]·(H₂O)₂} _n (1) (H₂MBD = 5-methoxycarbonyl-benzene-1,3-dicarboxylic acid, L = 1,3-bis(benzimidazol-l-yl)-2-propanol) is synthesized, in which the starting linker (benzene-1,3,5-tricarboxylic acid) undergoes selective monoesterification during the synthesis. In the structure of complex 1, each cadmium center is octahedrally coordinated by four O atoms from three carboxylate groups and two N of distinct L ligands. A detailed structural analysis reveales that compound 1 exhibits a unique 2D binodal (3,5)-connected (4².6⁷.8)(4².6) topology structure. Furthermore, the 2D layer is extended into a 3D network through π-π stacking interactions. The solid-state fluorescence properties of 1 are investigated at room temperature.     

The Injury and Cumulative Effects on Human Skin by UV Exposure from Artificial Fluorescence Emission

The injury and cumulative effects of UV emission from fluorescence lamp were studied. UV intensity from fluorescence lamp was measured, and human skin samples (hips, 10 volunteers) were exposed to low‐dose UV irradiation (three times per week for 13 consecutive weeks). Three groups were examined: control group without UV radiation; low‐dose group with a cumulative dose of 50 J cm^?2 which was equivalent to irradiation of the face during indoor work for 1.5 years; and high‐dose group with 1000 J cm^?2 cumulative dose equivalent to irradiation of the face during outdoor activities for 1 year. Specific indicators were measured before and after UVA irradiation. The findings showed that extending the low‐dose UVA exposure decreased the skin moisture content and increased the transepidermal water loss as well as induced skin color changes (decreased L* value, increased M index). Furthermore, irradiated skin showed an increased thickness of cuticle and epidermis, skin edema, light color and unclear staining collagen fibers in the dermis, and elastic fiber fragmentation. In addition, MMP‐1, p53 and SIRT1 expression was also increased. Long‐term exposure of low‐dose UVA radiation enhanced skin photoaging. The safety of the fluorescent lamp needs our attention.     

Kinetics of Transesterification of Methyl Acetate and Ethanol Catalyzed by Ionic Liquid

The kinetic behavior and chemical equilibria for the transesterification of methyl acetate with ethanol to ethyl acetate and methanol catalyzed by an ionic liquid 4‐(3‐methyl‐1‐imidazolio)‐1‐butanesulfonic acid hydrogen sulfate ([HSO₃‐bmim]HSO₄) were studied experimentally. The relationship of chemical equilibrium constants versus temperature was obtained from kinetic experimental data. The effects of temperature, initial molar ratio of ethanol to methyl acetate, and catalyst concentrations were investigated. Based on the reaction mechanism, an ideal homogeneous (IH) and two nonideal homogeneous models (NIH‐1, NIH‐2) were proposed to correlate the reaction kinetic data. The activity coefficient of the catalyst was considered in NIH‐2 but not in the NIH‐1 model. The nonideal homogeneous model NIH‐1 was the best model to describe the kinetics of the transesterification reaction, and the accuracy of the reaction kinetic model is not improved by considering the effects of catalyst on the activities of the reactants and products.     

导电聚合物热电材料研究进展

导电聚合物在室温下具有较高的电导率(σ)、较低的热导率(κ)、柔韧性好、易于合成、原料来源丰富、对环境无污染等优势,是目前最具有热电应用潜力的有机热电材料之一。然而,目前针对导电聚合物作为有机热电材料的相关研究依然处于初级阶段,其在空气气氛中的化学稳定性问题、低的热电优值及尚未完全明确的热电机制一直困扰着研究人员。本文主要针对以上问题,在对前人的研究成果进行综述的基础上对目前有机热电材料所面临的关键问题进行阐述和总结。     

原位合成具有高可见光催化活性的C3N4/CdS纳米复合材料

以硫氰酸铵和氯化镉为原料,采用无模板混合高温煅烧法一步合成氮化碳/硫化镉纳米晶(C3N4/CdS)的复合半导体材料。采用X射线衍射、傅立叶变换红外光谱和透射电镜等技术对其结构和形貌进行了表征。以有机污染物罗丹明B (RhB)为模拟污染物对复合催化剂的可见光催化活性进行测试。结果表明, C3N4/CdS复合材料中CdS以六方相纳米晶的形式均匀分散; CdS的复合基本不改变C3N4主体结构及聚合度;与纯C3N4相比,复合材料在可见区的光吸收能力有所增强。合适的能带匹配有利于光生载流子的迁移,抑制了其复合速率。在可见光照射下,复合半导体能够更加快速的降解有机污染物,且保持很好的稳定性。     

质子交换膜的传输通道微观结构对燃料电池性能的影响

质子交换膜燃料电池因其高效、高能量密度、快速启动等独特优势在便携电子设备及汽车动力装置等应用中极具发展潜力。质子交换膜内的传输通道由于对膜质子传导性能有重要影响而受到研究者们的广泛关注。构筑有序结构的质子传输通道,能够获得质子电导率与燃料渗透率、热稳定性、化学稳定性等性能均衡提升的新型质子交换膜材料。本文结合近年来质子传输通道的研究进展,对控制聚合物的相形态从而构筑有序质子传输通道的研究进行了综述,并针对不同相形态所形成的有序通道对膜及燃料电池性能的影响进行了分类与评述,最后对其发展趋势进行了展望。     

The selectivity of triethylene glycol modified glassy carbon electrode for charged and uncharged pieces

A triethylene glycol modified glassy carbon electrode(TEG–GCE) was fabricated by a controlledpotential electrolysis procedure. The performance of the film on the modified electrode surface was investigated by cyclic voltammetry with different probes. It was firstly found that while neutral pieces could penetrate the TEG film on the GCE surface, the ionic pieces, whatever it is anion or cation, was blocked by the film. This property was successfully used for determining dopamine(DA) in the presence of ascorbic acid(AA) with differential pulse voltammetry(DPV).     

Separation and purification of five alkaloids from Aconitum duclouxii by counter‐current chromatography

C₁₉‐diterpenoid alkaloids are the main components of Aconitum duclouxii Levl. The process of separation and purification of these compounds in previous studies was tedious and time consuming, requiring multiple chromatographic steps, thus resulted in low recovery and high cost. In the present work, five C₁₉‐diterpenoid alkaloids, namely, benzoylaconine ( 1 ), N‐deethylaconitine ( 2 ), aconitine ( 3 ), deoxyaconitine ( 4 ), and ducloudine A ( 5 ), were efficiently prepared from A. duclouxii Levl (Aconitum L.) by ethyl acetate extraction followed with counter‐current chromatography. In the process of separation, the critical conditions of counter‐current chromatography were optimized. The two‐phase solvent system composed of n‐hexane/ethyl acetate/methanol/water/NH₃·H₂O (25%) (1:1:1:1:0.1, v/v) was selected and 148.2 mg of 1 , 24.1 mg of 2 , 250.6 mg of 3 , 73.9 mg of 4, and 31.4 mg of 5 were obtained from 1 g total Aconitum alkaloids extract, respectively, in a single run within 4 h. Their purities were found to be 98.4, 97.2, 98.2, 96.8, and 96.6%, respectively, by ultra‐high performance liquid chromatography analysis. The presented separation and purification method was simple, fast, and efficient, and the obtained highly pure alkaloids are suitable for biochemical and toxicological investigation.     

Multi‐constituent determination and fingerprint analysis of Scutellaria indica L. using ultra high performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry

An ultra‐performance liquid chromatography coupled with quadrupole time‐of‐flight mass spectrometry method integrating multi‐constituent determination and fingerprint analysis has been established for quality assessment and control of Scutellaria indica L. The optimized method possesses the advantages of speediness, efficiency, and allows multi‐constituents determination and fingerprint analysis in one chromatographic run within 11 min. 36 compounds were detected, and 23 of them were unequivocally identified or tentatively assigned. The established fingerprint method was applied to the analysis of ten S. indica samples from different geographic locations. The quality assessment was achieved by using principal component analysis. The proposed method is useful and reliable for the characterization of multi‐constituents in a complex chemical system and the overall quality assessment of S. indica.     

基于微流控芯片的CD4+T淋巴细胞计数检测

CD4 +T淋巴细胞是人体免疫缺陷病毒(HIV)的主要感染细胞,慢性HIV感染者逐渐耗尽CD4 +T淋巴细胞,使免疫系统变弱,导致获得性免疫缺陷综合症(AIDS),因此,CD4 +T淋巴细胞的数量对HIV/AIDS的诊断和治疗至关重要。全球范围内HIV/AIDS正处于快速增长期,现有的CD4 +T淋巴细胞计数检测方法由于仪器昂贵、操作复杂、检测成本高,不利于疾病诊疗的普及与推广。为实现低成本、方便、快捷的临床检测,基于微流控芯片的CD4 +T淋巴细胞计数检测方法与技术的研究正日益受到人们的重视。本文在回顾传统CD4 +T淋巴细胞检测方法的基础上,综述、归纳了基于微流控芯片的CD4 +T淋巴细胞计数方法,在全面分析其技术特点的基础上,进一步评述了其综合性能、适用范围、及典型优缺点。最后,本文针对基于微流控芯片的CD4 +T淋巴细胞计数检测技术的发展趋势及商业化应用前景进行了讨论和展望。