用衰减全反射红外二向色性表征聚环氧乙烷薄膜的表面取向

应用衰减全反射二向色性表征聚合物的表面取向,可不必测定样品的折光率使大多数实验简化.以聚环氧乙烷为例.用衰减全反射偏振红外光谱测定了它的表面二向色性比和计算了相应的取向函数.     

Thermochemistry of thermal plasma chemical reactions. Part II. A survey of synthesis routes for silicon nitride production

Feasibility routes for thermal plasma production of silicon nitride powders are explored. First, a collation of the various proposed systems from the extant literature is examined. Reactant systems investigated include free silicon, silicon monoxide, silicon dioxide, silicon tetrachloride, silane, and other organosilicon precursors, along with various nitriding and reducing species. The reaction yields of these systems are brought to a common denominator by thermodynamic analysis and a first-step introduction of nucleation kinetics including comparisons against published experiments and the authors' own research. In particular, it is observed that the formation of liquid-phase free silicon in the neighborhood of 2500 K is quite detrimental to silicon nitride yield, and furthermore, a high supersaturation of silicon should always be avoided.     

不稳定中间体1-甲基-3,5-二苯基吡唑烷醇-3脱水反应的光谱研究

α,β-不饱和醛酮与单取代肼反应的产物是吡唑啉,据文献报道,反应是经过腙关环而得产物,我们的实验发现,苯丙烯酰苯(Ⅰ)与甲肼(Ⅱ)(1:1.05)在-5℃以下反应可以分离到一个白色不稳定的中间体1-甲基-3,5-二苯基吡唑烷醇-3(Ⅲ),它在-75℃稳定,温度升高时缓慢脱水生成产物卜甲基-3,5-二苯基吡唑啉(Ⅳ),甲肼和苯丙烯酰苯在此条件下生成吡唑啉的反应历程与以前文献报道的不同。     

含辅酶Q10材料的抗辐射性能及含量测定

采用高效液相色谱法测定了辅酶Q10(CoQ10)的含量,并探讨了CoQ10的防晒性能.色谱柱为Kromasil 5-C18柱(150×4.6 mm,5μm);流动相为甲醇-无水乙醇(体积比30:70),流速为1.0 mL/min;检测波长275 nm.实验考察了不同含量CoQ10在3个紫外区的防晒性能,及与维生素C或维...     

Oligonol inhibits UVB-induced COX-2 expression in HR-1 hairless mouse skin--AP-1 and C/EBP as potential upstream targets

Oxidative stress and inflammatory tissue damage are two major events frequently implicated in carcinogenesis. Numerous polyphenolic compounds derived from plants possess antioxidant and anti-inflammatory activities and are hence effective in preventing cancer. Oligonol is a polyphenol formulation enriched with catechin-type oligomers. As an initial approach to assess the chemopreventive potential of oligonol, we have determined its effects on inflammatory as well as oxidative damage in mouse skin irradiated with UVB. Topical application of oligonol onto the dorsal skin of male HR-1 hairless mice 30 min prior to UVB exposure diminished epidermal hyperplasia and formation of 4-hydroxynonenal, a biochemical hallmark of lipid peroxidation. Topical application of oligonol also significantly inhibited UVB-induced cyclooxygenase (COX-2) expression in mouse skin. Oligonol diminished the DNA binding of activator protein-1 (AP-1) and CCAAT/enhancer binding protein (C/EBP), and the expression of C/EBPdelta in mouse skin exposed to UVB. Our study also revealed that oligonol attenuated UVB-induced catalytic activity as well as expression of p38 mitogen-activated protein (MAP) kinase. Moreover, UVB-induced phosphorylation of another upstream kinase Akt was attenuated by oligonol. Taken together, oligonol showed antioxidative and anti-inflammatory effects in UVB-irradiated mouse skin by inhibiting COX-2 expression via blockade of the activation of AP-1 and C/EBP, and upstream kinases including p38 MAP kinase and Akt.     

Recent advances in electric analysis of cells in microfluidic systems

Microfluidics offers an ideal platform to integrate cell-based assays with electric measurements. The technological advances in microfluidics, microelectronics, electrochemistry, and electrophysiology have greatly inspired the development of microfluidic/electric devices that work with a low number of cells or single cells. The applications of these microfluidic systems range from the detecting of cell culture density to the probing of cellular functions at the single-cell level. In this review, we introduce the recent advances in the electric analysis of cells on a microfluidic platform, specifically related to the quantification and monitoring of cells in static solution, on-chip patch-clamp measurement, and examination of flowing cells. We also point out future directions and challenges in this field. Figure Different microfluidic devices applied to electrical analysis of cells     

Micro-/Mesoporous conjugated polymer based on star-shaped triazine-functional triphenylamine framework as the performance-improved cathode of Li-organic battery

A novel organic conjugated polymer based on star-shaped triazine-functional triphenylamine framework poly[1,3,5-tris(4-diphenylamino-phenyl)triazine] (PTDAPTz) is designed and synthesized successfully by FeCl₃-catalysted chemical oxidative polymerization. The polymer PTDAPTz powder exhibits a compactly packed pleated skirt shape-like morphology with a high surface area (~930 m² g⁻¹) and a bimodal pore size distribution ranging from micropores (~0.55 nm) to small diameter mesopores (~2–6 nm). As explored as the cathode material, the obtained PTDAPTz presents the double charge–discharge process characteristics of both the free radical redox of triphenylamine unit and the bipolar redox of triazine unit in the polymer and a well-defined multistage charge/discharge voltage plateau (~3.8 V for p-doped and ~2.0 V for n-doped) during the charge–discharge process. Also, the PTDAPTz demonstrates an improved capacity (stabilized at 123 mA h g⁻¹ until 50th cycle) and the enhanced rate performance compared to polytriphenylamine (PTPAn). Specially, the discharge curve for the part of triphenylamine unit presents an obviously improved discharge plateau (~3.8 V for PTDAPTz compared to ~3.6 V for PTPAn) due to the electron-withdrawing effect of the triazine unit to triphenylamine. The elaborate structural design and created micro-/mesoporous morphology with the double charge–discharge process make PTDAPTz a potential candidate as the performance-improved cathode of Li-organic battery. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 2574–2583     

Platinum/carbon black composites as counter electrodes for high-performance dye-sensitized solar cells

Journal of Solid State Electrochemistry - Low-cost counter electrodes for dye-sensitized solar cells (DSSCs) are prepared using platinum/carbon black (Pt/CB) composites via a spin-coating process....     

Hydrodechlorination of chlorophenols over Pd catalysts supported on zeolite Y,MCM-41 and graphene

Hydrodechlorination (HDC) reaction of chlorophenols was carried out using Pd catalysts supported over zeolite Y, MCM-41 or graphene. Pd-MCM-41 and Pd-Y zeolite were prepared by impregnation and ion-exchange method, respectively. Pd-graphene (Pd-G) was prepared by hydrazine hydrate reduction of palladium ion dispersed on graphene oxide. The catalysts were characterized by several analytical tools such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). These catalysts were subjected to HDC reaction of chlorophenols, such as 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), 2,6-dichlorophenol (2,6-DCP) and 3,4-dichlorophenol (3,4-DCP). The reaction rate of HDC of chlorophenols catalyzed by Pd catalysts with various solid bases, such as KF/Al₂O₃ (alumina), sodium acetate (NaOAc) and K₂CO₃ was compared. First, Pd-MCM-41 and Pd-Y catalysts were compared. 2,4- and 3,4-DCPs were completely decomposed within 6 h, in the case of Pd-MCM-41 with NaOAc. Using Pd-Y instead of Pd-MCM-41 with NaOAc, much faster decomposition was observed. Faster decomposition of 4-CP and DCPs was observed with NaOAc base than K₂CO₃ or KF/Al₂O₃ under the same condition. In the case of Pd-Y with KF/Al₂O₃, slower decomposition of 4-CP and DCPs was observed. These base effects were interpreted using the solubility of NaCl and KCl in alcohol and the basic sites of KF/Al₂O₃. Because the solubility of NaCl is known to be larger than KCl solubility in alcohol, byproduct NaCl could be easily dissolved and ionized in solvents. For Pd-Y with KF/Al₂O₃, the small pore size of Y zeolite can interfere with the diffusion of HCl to KF/Al₂O₃ basic site. Second, three catalysts, including Pd-graphene, were compared. 2,4-DCP was decomposed within 2 h using Pd-G with either K₂CO₃, NaOAc or KF/Al₂O₃. Pd-G catalyst showed the highest catalytic activity among Pd-G, Pd-MCM-41 and Pd-Y catalysts. The high activity and stability of the Pd-G could be attributed to the strong metal–support interaction with an electron-deficient site and a critical Pd particle size (ca. 3.5 nm) of Pd-G nanocatalyst with a stronger resistance to the deactivation and good affinity toward aromatic organic molecules, especially phenols. The progress of HDC reaction was monitored by gas chromatography with flame ionization detection (GC/FID), and a feasible degradation process could be explained by analyzing the degradation products such as phenol, cyclohexanone and cyclohexanol from resulting GC chromatograms. The effect of reaction temperature on HDC in Pd-G catalyst was also discussed. In conclusion, Pd-G is an efficient catalyst for decomposition of chlorophenols and can be applied to remediation of chlorophenol-contaminated water under mild conditions.     

Highly efficient control of thrombin activity by multivalent nanoparticles

We have demonstrated that the incorporation of sulfated galactose acid (sulf-Gal) into thrombin-binding-aptamer (TBA)-conjugated gold nanoparticles (TBA-AuNPs) enables highly effective inhibition of thrombin activity toward fibrinogen. AuNP bioconjugates (TBA(15)/TBA(29)/sulf-Gal-AuNPs) were prepared from 13 nm AuNPs, 15-mer thrombin-binding aptamer (TBA(15)), 29-mer thrombin-binding aptamer (TBA(29)), and sulf-Gal. The numbers of TBA and sulf-Gal molecules per AuNP proved to have a strong impact on inhibitory potency. The best results were observed for 15-TBA(15)/TBA(29)/sulf-Gal-AuNPs (with 15 TBA(15) and 15 TBA(29) molecules per AuNP), which, because of their particularly flexible conformation and multivalency, exhibited ultrahigh binding affinity toward thrombin (K(d)=3.4×10(-12) M) and thus extremely high anticoagulant (inhibitory) potency. Compared to the case without inhibitors (the "normal" value), their measured thrombin clotting time (TCT) was 91 times longer, whereas for TBA(15) alone it was only 7.2 times longer. Their anticoagulant activity was suppressed by TBA-complementary-sequence (cTBA)-modified AuNPs (cTBA(15)/cTBA(29)-AuNPs) at a rate that was 20 times faster than that of free cTBA(15)/cTBA(29). Thus, easily prepared, low-cost, multivalent AuNPs show great potential for biomedical control of blood clotting.