Ethane cation decomposition characterization by EBMI spectroscopy: gas‐phase dissociative recombination as a source of secondary products

The decomposition products of the d₆‐ethane cation following charge‐transfer ionization with Ar⁺, under conditions of varying ionization electron current, have been isolated in solid argon matrices at 18 K and examined using Fourier transform infrared spectroscopy. Gas samples containing 1 : 1600 d₆‐ethane : Ar were subjected to electron bombardment by using either a high (pin) or a low (plate) ionization density anode configuration with ionization currents between 20 and 150 μA. Under high ionization density conditions, the observed major products were d₄‐ethene (C₂D₄) and d₂‐acetylene (C₂D₂), with smaller yields of C₂D₅, C₂D₃, and C₂D. The yield of each dehydrogenation product was enhanced with increased current. Analogous experiments employing the low ionization density plate anode resulted in reduced C₂D₆ destruction and the formation of only C₂D₄ and C₂D₂. The results suggest the onset of dissociative recombination processes under high ion density conditions. In this context, the results can be interpreted as a dissociative recombination of primary ion products, which gives rise to further dehydrogenation, and appearance of additional neutral radical products. Copyright © 2012 John Wiley & Sons, Ltd.     

IL-17-deficient allogeneic bone marrow transplantation prevents the induction of collagen-induced arthritis in DBA/1J mice

IL-17-producing CD4⁺ T cells (Th17) play important functions in autoimmune diseases and allograft rejection of solid organs. We examined the effects of IL 17 and its mechanism of action on arthritis in a murine collagen-induced arthritis (CIA) model using bone marrow transplantation (BMT) system. DBA/1J mice were administered a lethal radiation dose and then rescued with bone marrow derived from either wild-type (WT) or IL-17^-/- mice on C57BL/6 background mice. CIA was induced after the bone marrow transplant, and disease progression was characterized. DBA/1J mice with CIA that received IL-17^-/- donor bone marrow showed potently inhibited development and severity of clinical arthritis as compared with CIA mice that received WT bone marrow. Reduced secretion of the pro-inflammatory cytokines tumor necrosis factor-α, IL-1β, and IL-6, and collagen-specific T cell responses were observed in mice that received IL-17^-/- bone marrow. IL-17 blockade also inhibited effector T cell proliferation by reciprocally regulating the Treg/Th17 ratio. IL-17 blockade prevented joint destruction in mice with CIA. These findings suggest that CIA with BMT is a viable method of immunological manipulation and that IL-17 deficiency suppresses severe joint destruction and inflammation in CIA mice. There may be clinical benefits in blocking IL-17 and BMT in the treatment of rheumatoid arthritis.     

新型梳状共聚物在准固态染料敏化太阳能电池中的应用及其对电子复合的影响

合成了乙烯基咪唑碘盐(VImI)和聚乙二醇单甲醚甲基丙烯酸酯(PEGMA)的梳状共聚物.利用VImI/PEGMA共聚物制备了准固态聚合物电解质.通过光电流密度-电压(J-V)曲线和电导率测定以及电化学阻抗分析,探讨了基于此电解质的染料敏化太阳能电池的电荷传输与界面电子转移机制.结果表明,VImI/PEGMA共聚物可以有效抑制TiO2/电解质界面电子复合并提高TiO2导带能级,敏化电池的光伏性能并不完全取决于电解质的电导率.通过考察共聚物中VImI与PEGMA单元的摩尔比与开路电压的关系,发现共聚物对电子复合的抑制作用主要源于VImI链段.此外,开路电压衰减(OCVD)和瞬态光电流测试结果说明,共聚物能够提高TiO2薄膜的电子寿命,而且对陷阱电子能级的分布具有调节作用.当共聚物在电解质中的质量分数为50%,VImI与PEGMA的摩尔比为5.0时,准固态染料敏化太阳能电池于100mW·cm-2光强下获得了4.10%的光电转换效率.     

Expression, refolding, and characterization of GFE peptide-fused human interferon-α2a in Escherichia coli

Interferon-α2a (IFN-α2a) has been used for the treatment of various viral infections and cancers for many years. However some untolerable side effects have limited its application in some aspects. To evaluate whether or not an oligopeptide containing GFE motif can home human IFN-α2a to specific tissues, a fusion gene was constructed by fusing the coding sequence of GFE peptide (CGFECVRQCPERC), which was screened from phage display peptide library, to the 3′ end of human IFN-α2a gene by recombinant DNA technique. Fusion protein rhIFN-α2a-GFE was expressed in Escherichia coli as inclusion bodies using a T7 RNA polymerase expression system, pET-22b, refolded through dialysis and purified to homogeneity to >95% of purity by affinity chromatography. Characterization by sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunoblotting demonstrated the authenticity of the fusion protein. Purified rhIFN-α2a-GFE was found to be functionally active in terms of its antiviral activity for about 2.5×10⁸ IU/mg in vitro. Yields of the purified fusion protein were about 200 mg/L of culture medium. Tissue distribution assay in mouse showed that at 30 min IFN-α2a could be enriched sevenfold higher in lung in the targeted IFN group of mice than in the standard IFN group of mice, and last for a long time. At 1 h, IFN-α2a in the targeted IFN group was still 4.02-fold higher than that in the standard group. This confirmed that GFE peptide has the ability to selectively deliver its fusion partner IFN-α2a to lungs. The results also showed that the IFN-α2a-GFE could be specifically enriched in kidney and liver. Its distribution in kidney was concordant with the finding of GFE receptor, MDP, in kidney. However, the IFN-α2a-GFE in liver may imply some significance in pharmacology and toxicology.     

三波段白光有机电致发光器件及其色稳定性的控制

制备并研究了基于3种小分子荧光材料的白光有机电致发光器件。发光层采用红色发光材料DCJTB掺杂绿光材料Alq3构成混合发光层,与OXD-7构成的蓝色发光层形成异质结的结构,并以NPB为空穴注入层。通过改变结构参数详细研究了发射光谱及其色坐标的电场依赖性。通过分析载流子注入/传输特性,控制激子的复合区域等措施得到了色坐标稳定性好、光谱丰富的高性能白光电致发光器件。经过优化的器件结构可以覆盖更大的可见光区域,当电压从9 V增加到13 V时,色坐标仅从CIE(x,y)=(0.364,0.314)偏移到CIE(x,y)=(0.332,0.291),具有较好的色稳定性。     

Resonant Fragmentation of the Water Cation by Electron Impact: a Wave-Packet Study

We have investigated the dissociation of a resonant state that can be formed in low energy electron scattering from H₂O⁺. We have chosen the second triplet resonance above the state of H₂O⁺ whose autoionization mainly produces H₂O⁺ ( ). We have considered both dissociation of the resonant state itself, dissociative recombination (DR), or the dissociation of the H₂O⁺ cation after autodetachment, dissociative excitation (DE). The time-evolution of a wave packet on the potential energy surfaces of the resonance and cationic states shows, for the initial conditions studied, that the probability for DR is about 38 % while the probability for DE is negligible.     

Influence of carbazol-9-yl substitution in polysilanes on charge carrier trapping and recombination

A series of poly{[3-(carbazol-9-yl)propyl]silane-co-methylphenylsilane}s were investigated by optical absorption, photoluminescence and thermoluminescence measurements. It was found that the optical absorption bands of the carbazolyl side groups superimpose on those of the Si backbones in the ultraviolet range. This feature reduces photodegradability of Si-Si bonds during UV irradiation. The TL spectra recorded in the 15 - 325 K temperature range after photoexcitation at 15 K show that the carbazolyl side groups act as trapping sites in polysilanes. Increasing density of carbazolyl groups results in increasing population of deeper (ca. 150 meV) traps. Spectral analyses of the thermoluminescence at different temperatures are discussed and compared with analogous results for poly(9-vinylcarbazole) (PVK). It is concluded that the monomeric mechanism of luminescence dominates at low temperatures while the excimeric mechanism prevails at higher temperatures, similarly to PVK.     

Light Emitting Diodes Fabricated from Liquid Phase Epitaxial InAs/InAsxP1‐x‐ySby/InAsx'P1‐x'‐y'Sby' and InAs/InAs1‐xSbx Multi‐Layers

Mid‐infrared light emitting diodes (LED) in 3‐5μm wavelength range have been fabricated from InAs/InAs_xP_1‐x‐ySb_y/InAs_x'P_1‐x'‐y'Sb_y' composition graded layer and InAs/InAsSb multilayers. The heterostructures were grown by liquid phase epitaxy (LPE) between 600 and 520°C. An output power of 3.1 mW at 11K and of 10 μW at 300 K have been obtained under a peak current of 100 mA (50 % duty ratio) from InAsSb multilayers. Recombination mechanisms for these diodes were studied by temperature‐dependent emission spectra using Fourier transform infrared (FTIR) measurement system with double modulation. The output powers of the LEDs decrease rapidly at temperatures above 153 K suggesting that nonradiative and Auger recombinations are the main limitation of the device performance at high temperatures.     

Single-molecule tethered particle motion to study protein-DNA interaction

Single-molecule techniques have been demonstrated as powerful tools to investigate individual protein-DNA interactions that are difficult to access by conventional biochemical techniques. These methods are popularly used to obtain valuable and detailed molecular mechanisms of enzyme functions. Currently, we have used single-molecule tethered particle motion to investigate protein-DNA interactions, including homologous recombination, site-specific recombination, DNA package, and the nucleosome remodeling process, and useful information was obtained. Here, we will describe the experimental designs and present the information obtained.