Synergistic Impact of Solvent and Polymer Additives on the Film Formation of Small Molecule Blend Films for Bulk Heterojunction Solar Cells

The addition of polystyrene (PS), a typical insulator, is empirically shown to increase the power conversion efficiencies (PCEs) of a solution‐deposited bulk heterojunction (BHJ) molecular blend film used in solar cell fabrication: p‐DTS(FBTTh₂)₂/PC₇₁BM. The performance is further improved by small quantities of diiodooctane (DIO), an established solvent additive. In this study, how the addition of PS and DIO affects the film formation of this bulk heterojunction blend film are probed via in situ monitoring of absorbance, thickness, and crystallinity. PS and DIO additives are shown to promote donor crystallite formation on different time scales and through different mechanisms. PS‐containing films retain chlorobenzene solvent, extending evaporation time and promoting phase separation earlier in the casting process. This extended time is insufficient to attain the morphology for optimal PCE results before the film sets. Here is where the presence of DIO comes into play: its low vapor pressure further extends the time scale of film evolution and allows for crystalline rearrangement of the donor phase long after casting, ultimately leading to the best BHJ organization.     

越冬期间香蕉果穗套袋的防寒效果及其对产量的影响

冬季香蕉果穗用兰色聚乙烯薄膜套袋之后,可提高袋内温度1～5℃,果实低温伤害卑只有1％左右,而未经套袋的达23％～35％,果指长度和径围增加率分别达12％和9％左右,果实产量比对照增加8％～16％。试验结果表明,兰色聚乙烯薄膜套袋是越冬期间香蕉防寒保果和增产的一项有效措施。     

聚赖氨酸修饰丝素蛋白膜对神经干细胞生长和分化的影响

利用聚赖氨酸修饰丝素蛋白膜,观察其对神经干细胞(NSCs)生长及分化的影响,为中枢神经系统损伤修复材料的选择提供实验基础和理论依据。文中首先制备聚赖氨酸修饰的丝素蛋白膜,并通过核磁共振图谱和紫外-可见光谱进行验证。NSCs分别接种在单纯丝蛋白膜(Silk)、聚赖氨酸修饰的丝蛋白膜(Silk-PIL)和多聚赖氨酸(PLL)上进行培养,分别在1、3、5、7 d时用CCK-8检测NSCs增殖活性。在第7天时,用免疫荧光染色检测NSCs分化情况,Western blotting和TUNEL检测细胞凋亡水平,Real-time PCR检测脑源性神经营养因子(BDNF)mRNA水平。结果表明,核磁共振图谱和紫外-可见光谱证明聚赖氨酸成功地接枝到了丝素蛋白膜上,CCK-8检测显示:从第3天开始一直到第7天,NSCs在Silk-PIL上的增殖活性要显著高于Silk组(P0.05),而与PLL组无显著性差异(P0.05)。免疫荧光观察显示,NSCs在Silk-PIL上分化成神经元的细胞显著多于Silk组(P0.05),而与PLL组无显著性差异,3个组之间分化为星型胶质细胞的数量并无显著性差异。Western blotting和TUNEL检测结果表明Silk-PIL组NSCs凋亡程度显著小于Silk组(P0.05),但与PLL组无显著性差异(P0.05)。RT-PCR结果显示,NSCs在Silk-PIL和PLL组的BDNFmRNA表达水平显著高于Silk组(P0.05)。结果表明,聚赖氨酸修饰的丝素蛋白膜能够促进NSCs的增殖活性并减少NSCs细胞凋亡,同时促进NSCs向神经元方向分化,有望成为新型组织工程支架材料搭载NSCs移植修复中枢神经系统损伤。     

地膜覆盖和施氮量对旱作春玉米农田净温室效应的影响

以旱作雨养条件下的春玉米为试验对象,在长武黄土高原农业生态试验站进行田间试验,研究了地膜覆盖和施氮量对农田净温室效应和温室气体排放强度的影响.结果表明:采用地膜覆盖与增加施氮量都会影响净温室效应与温室气体排放强度,地膜覆盖条件下(FM),不同施氮量的春玉米产量为1643~16699 kg·hm-2,净温室效应(CO_2当量,下同)为595~4376 kg·hm^-2·a^-1,温室气体排放强度为213~358 kg·t^-1;无覆膜条件下(UM),不同施氮量的春玉米产量为956~8821 kg·hm-2,净温室效应为342~4004 kg·hm^-2·a^-1,温室气体排放强度为204~520 kg·t^-1.研究表明,对于旱作春玉米农田系统,地膜覆盖可以有效降低温室气体排放强度,增加作物产量,地膜覆盖下施氮250 kg·hm-2可以实现高产与降低环境代价的双赢.     

Determination of the absolute configurations of synthetic daunorubicin analogues using vibrational circular dichroism spectroscopy and density functional theory

The absolute configurations of three synthesized anthracycline analogues have been determined using vibrational circular dichroism (VCD) spectroscopy and the density functional theory (DFT) calculations. The experimental VCD spectra of the three compounds have been measured for the first time in the film state, prepared from their CDCl₃ solutions. Conformational searches for the monomers and some dimers of the three compounds have been performed at the DFT level using the B3LYP functional and the 6‐311G** and 6‐311++G** basis sets. The corresponding vibrational absorption and VCD spectra have been calculated. The good agreement between the experimental and the calculated spectra allows one to assign the absolute configurations of the three compounds with high confidence. In addition, the dominant conformers of the three compounds have also been identified. Chirality, 2010. © 2010 Wiley‐Liss, Inc.     

Monte Carlo dose in a prosthesis phantom based on exact geometry vs streak artefact contaminated CT data as benchmarked against Gafchromic film measurements

PurposeIn radiotherapy, accurate calculation of patient radiation dose is very important for good clinical outcome. In the presence of metallic implants, the dose calculation accuracy could be compromised by metal artefacts generated in computed tomography (CT) images of patients. This study investigates the influence of metal-induced CT artefacts on MC dose calculations in a pelvic prosthesis phantom.MethodsA pelvic phantom containing unilateral Ti prosthesis was CT-scanned and accurate Hounsfield unit (HU) values were assigned to known materials of the phantom as opposed to HU values produced through the artefact CT images of the phantom. Using the DOSXYZnrc MC code, dose calculations were computed in the phantom model constructed from the original CT images containing the artefacts and artefact-free images made from the exact geometry of the phantom with known materials. The dose calculations were benchmarked against Gafchromic EBT3 film measurements using 15 MeV electron and 10 MV photon beams.ResultsThe average deviations between film and MC dose data decreased from 3 ± 2% to 1 ± 1% and from about 6 ± 2% to 3 ± 1% for the artefact and artefact-free phantom models against film data for the electron and photon fields, respectively.ConclusionsFor the Ti prosthesis phantom, the presence of metal-induced CT artefacts could cause dose inaccuracies of about 3%. Construction of an artefact-free phantom model made from the exact geometry of the phantom with known materials to overcome the effect of artefacts is advantageous compared to using CT data directly of which the exact tissue composition is not well-known.     

DNA hybridization detection with organic thin film transistors: toward fast and disposable DNA microarray chips

We demonstrate a novel DNA hybridization detection method with organic thin film transistors. DNA molecules are immobilized directly on the surface of organic semiconductors, producing an unambiguous doping-induced threshold voltage shift upon hybridization. With these shifts, single-stranded DNA (ssDNA) and double-stranded DNA (dsDNA) are differentiated successfully. This method is expected to result in higher sensitivity than the main competitive technology, ISFET-based sensors because of the direct exposure of DNA molecules to sensitive layers. Factors that influence sensor sensitivity have been analyzed and optimum conditions have been determined using statistically designed experiments. Under the optimum conditions, the maximum difference between saturation current ratios caused by ssDNA and dsDNA reaches as high as 70%. In order to make DNA detection fast, we also demonstrate rapid on-chip electrically enhanced hybridization using the TFTs. These technologies together will enable the realization of disposable, rapid-turnaround tools for field-deployable genomic diagnosis.     

残留地膜对番茄幼苗形态和生理特性的影响

采用盆栽试验的方法,研究了土壤中残留地膜对番茄(Lycopersicon esculentum L.)幼苗形态及生理特性的影响.结果表明,残留地膜使番茄幼苗的株高、茎粗、地上部和根系鲜重、根系活力及叶片氮代谢水平等降低;而且根系的IBA含量降低和ABA含量增加,抑制了根系的生长.同时地膜残留量越大,抑制的效果越显著.这...     

Molecularly imprinted polymer films for reflectometric interference spectroscopic sensors

Reflectometric interference spectroscopic measurements were performed on molecularly imprinted polymer (MIP) films with the herbicide atrazine as the template molecule. A conventional imprinting protocol was used relying on non-covalent interactions between the functional monomers and the template. The MIPs were deposited on glass transducers by two different methods: spin-coating followed by in situ polymerization of thin films of monomers containing a sacrificial polymeric porogen, and autoassembly of MIP nanoparticles with the aid of an associative linear polymer. Reproducible results were obtained upon measurements of atrazine solutions in toluene with both films. Atrazine concentrations as low as 1.7 ppm could be detected with the autoassembled particle film. No or very little analyte adsorption was observed onto non-imprinted control films made by spin-coating and by particle assembly, respectively. We believe that these MIP layers in combination with the general reflectrometric transduction scheme could be a versatile sensing tool for the detection of environmentally important and other analytes.