47 resultados para Broad-spectrum

em Chinese Academy of Sciences Institutional Repositories Grid Portal


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A novel Nd3+-doped lead fluorosilicate glass (NPS glass) is prepared by a two-step melting process. Based on the absorption spectrum a Judd-Ofelt theory analysis is made. The emission line width of NPS glass is 44.2nm. The fluorescence decay lifetime of the 4F3/2 level is 586±20μsec, and the stimulated emission cross-section is 0.87×10-20cm2 at 1056nm. A laser oscillation is occurred at 1062nm when pumped by 808nm Diode Laser. The slope efficiency is 23.7% with a 415mJ threshold. It is supposed that NPS glass is a good candidate for using in ultra-short pulse generation and amplification by the broad emission bandwidth and long fluorescence lifetime.

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We theoretically propose a method of generating a single sub-100 attosecond (as) pulse with a two-colour time-gating laser field. The field is synthesized by an 8 fs/800 nm (three optical cycles) pulse and a 24 fs/2400 nm (three optical cycles) pulse with an optimal time delay between them. In our simulation, we obtain a supercontinuum with an extremely broad spectrum of 150 eV and generate an isolated attosecond pulse with 96 as pulse duration without any dispersion compensation.

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系统获得性抗性(Systematic acquired resistance, SAR)是植物抵御病原菌侵染的最有效手段,利用基因工程技术导入SAR信号发生过程中的关键基因后,植物的SAR基因表达量提高并且对病原菌侵染的反应速度加快,因此植物的抗病性得以增强,与传统的抗病基因工程技术相比它对病原菌没有专一性,许多学者称之为广谱抗病基因工程,该领域已成为目前抗病基因工程研究的热点和前沿。 NDR1和NPR1基因在植物的SAR发生中起着重要的作用,前者功能定位在ROS(reactive oxygen species)的激活和随后的水杨酸(SA)诱导合成之间,突变株病原菌诱导后SA合成能力降低,SAR发生减弱,目前还没有对该基因进行过量表达分析的报道;后者功能定位在SAR信号转导级联反应之中的SA积累和随后的SAR基因表达之间。该突变株在病原菌侵染时不产生病程相关蛋白(PRs),表现为感病,而对照抗病;过量表达该基因的转基因拟南芥对多种病原菌的侵染产生抗性,PR1等PRs蛋白的表达量也提高,异源表达该基因的水稻对白叶枯病的抗性也提高。本研究利用RT-PCR方法从拟南芥中克隆了这两种基因,序列分析表明拟南芥Wassilewskija生态型的NDR1基因与Columbia生态型相比,共有7处碱基不同,引起编码氨基酸变化4处,而NPR1基因与报道的Wassilewskija生态型来源的NPR1基因完全相同。 我们构建了35S启动子驱动的NDR1和NPR1基因的植物组成型高效表达载体,利用农杆菌介导法转化烟草,PCR和Southern鉴定外源基因已经整合到植物基因组中。抗病性分析显示过量表达NDR1和NPR1基因的烟草对晚疫病和赤星病的抗性都有明显提高,说明这两个基因的在其它植物中异源表达后,都能提高植物对多种病原菌的抗性。 本论文提出了利用这两个基因来培育抗黄萎病棉花的设想,一方面为解决这个“世纪性”难题积累新的资料,另一方面也为其它作物的抗病基因工程提供新的经验。利用35S启动子驱动的NDR1和NPR1基因的植物组成型表达载体分别对陆地棉品种石远321进行花粉管通道法转化。同时,还探讨了这两个基因在棉花中的共转化实验,希望它们的“协同增效”能进一步提高棉花的抗病性。对其中2001年夏天在南京注射所获得的5,000粒种子在三亚进行100 g/ml卡那霉素筛选,初步鉴定分别获得转NDR1和NPR1基因株系26和24棵,PCR进一步鉴定其中分别有12和7棵为转基因阳性,转基因频率分别为0.50%和0.27%,目前利用营养钵蘸根法对其二代进行抗枯、黄萎病鉴定,结果显示有转基因植株对枯、黄萎病的抗性都明显增强,进一步的鉴定正在进行中。2002年初海南注射分别获得转NDR1和NPR1基因以及共转化种子22,000、10,500和12,500粒种子,2002年夏在中国农科院植保所黄萎菌病圃筛选抗黄萎病单株,并利用100 g/ml卡那霉素初步筛选出了一批抗性植株,每种转基因株系随机挑选5株进行PCR鉴定,结果显示为阳性。进一步的抗黄萎病鉴定和筛选以及分子分析正在进行中。 同时,本文还探讨了病原菌诱导型启动子在广谱抗病基因工程应用的可能性。根据烟草的Pr1-a启动子已知序列设计引物,PCR扩增启动子序列后,构建病原菌诱导型NPR1基因植物表达载体,并对棉花进行转化,获得种子11,500粒,利用同上的筛选方法,获得了一致的结果,目前抗黄萎病鉴定、分子检测以及生物学分析正在进行中。 最后,鉴于抗生素标记在转基因植物的应用引起了许多“安全性”争论的事实,还构建了无筛选标记的表达载体对抗虫棉进行转化,这样在生产上可以直接获得抗虫棉抗黄萎病棉花新材料,也为其它作物抗病基因工程积累经验。 本研究还提出了一种较为有效的提取高质量棉花总RNA的方法,与原来一些棉花RNA纯化方法相比,该方法所用都为常规试剂,易于重复,质量高。并且利用获得的总RNA构建了黄萎菌激发子诱导的cDNA文库,滴度测定为1╳107pfμ/μg,插入片段大小在5 00~2 000 bp范围内。 鉴于NPR1基因研究的重要性,本研究还利用简并引物PCR技术从海岛棉和陆地棉的基因组中都分离到了NPR1基因的同源片段,大小都为208 bp,与拟南芥NPR1基因的相应部分的同源性分别为66%和65%,它们之间的同源性为87%,目前该基因的全长正在分离鉴定中。 多聚半乳糖醛酸酶抑制蛋白(PGIPs)在植物的防御反应中起着重要的作用,通过分析已知20余种pgip基因序列的保守区,设计简并引物,PCR扩增海岛棉(Gossypium barbadense)7124 cDNA文库,得到一条长561 bp的片段,序列测定后分析确认为pgip基因的一部分。根据此序列和棉花病原菌诱导的cDNA文库载体中已知部分设计RACE引物,扩增后,5’和3’RACE分别得到666bp和906 bp的片段。序列分析表明它具有完整的编码框,产物为330 aa的蛋白质。序列分析该蛋白具有10个串联的LRR(leucine-rich repeat)区,与柑桔(Citrus)和枳(Poncirus)的pgip基因的同源性分别为69.2%和68.7%。进一步PCR扩增得到该基因的全长阅读框,并且获得了相应的基因组片段,序列分析发现该基因没有内含子。这是从棉属植物中克隆的第一个pgip基因。

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Two antimicrobial peptides manifested a broad spectrum of anti microbial activity against various microorganisms have been isolated from skin secretions of Rana grahami. These antimicrobial peptides were named grahamin 1 and grahamin 2. Their primary Stru

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5-氟尿嘧啶(5-Fluorouracil, 5-FU)是一种抗代谢药物,广泛用于临床治疗结直肠癌、胃癌、乳腺癌等多种癌症,但其首过代谢显著、亲脂性较低,选择性差、毒副作用大。为克服这些缺点人们对5-FU进行了大量的修饰工作,包括小分子修饰以及与各种载体形成微球、微囊、纳米粒、共价前药等。 环糊精(Cyclodextrin,简称CD),可被结肠中的糖苷酶特异性地降解成小分子糖,而胃和小肠中由于缺乏相应的酶而使环糊精不被降解,这一特性在结肠药物的靶向输送及释放中有重要应用价值。环糊精中含有丰富的羟基,易进行化学修饰,将药物与环糊精通过共价键结合制成前药,使其在胃和小肠中不降解,而在盲结肠中被特异性的酶降解释出药物,达到结肠靶向释药的目的。研究表明,环糊精作为一种前药载体为结肠靶向释药和缓释、控释系统提供了一种有效的手段。 本工作选择5-氟尿嘧啶为模型药物、β-环糊精作为载体,通过中间体5-FU羧酸衍生物的制备及其与β-环糊精的偶联,合成了系列5-FU-β-CD前体药物,并利用紫外、红外、质谱、核磁、元素分析、热分析等手段对其进行结构表征。同时,还研究了前体药物的体外释药性质。具体内容包括: 1. 含有羧基的5-FU衍生物中间体的合成:(5-氟尿嘧啶-1-基)-乙酸(FUAC)、3-(5-氟尿嘧啶-1-基)-丙酸(FUPC)、5-(5-氟尿嘧啶-1-基)-戊酸(FUVC)的合成。 2. 中间体5-FU的羧酸衍生物与β-CD的偶联:分别通过以6-OTs-β-CD为中间体的取代法和活化酯法,合成了第一面取代和第二面取代的5-FU-β-CD大分子前体药物。在二面取代的前体药物制备中,通过改变原料的比例,合成了系列不同取代度(DS)的2-[(5-氟尿嘧啶-1-基)-乙酰基] -β-环糊精结合物。 3. 对上述前体药物进行体外释放研究:分别考察了前体药物在不同pH缓冲溶液中的水解行为及其在小鼠胃肠道人工体液中的酶解行为,并通过UV-Vis及HPLC对前体药物释放情况进行检测分析。 5-Fluorouracil(5-Fu), commonly known as a broad-spectrum antineoplastic drug, has been widely used in the treatment of various kinds of cancer including colon cancer for 40 years. However, this antitumor agent exhibits serious adverse effects, such as their marrow toxicity, gastrointestinal reaction and low selectivity in their clinical use. In order to improve its antitumor activity and reduce its toxicity, the compound was modified in various ways, including the formation of conjugated prodrugs with kinds of carrier, microsphere and nanoparticles etc. Cyclodextrins(CDs) are known to be barely capable of being hydrolyzed and only slightly absorbed in passing through the stomach and small intestine; however they are fermented into small saccharides by colonic microflora and thus absorbed as small saccharides in the large intestine. This biodegradation property of CDs may be useful as a colon-targeting carrier, and thus CD prodrugs may serve as a source of site-specific delivery of drugs to colon. It was demonstrated that prodrugs of CDs can provide a versatile means for construction of not only colon targeted delivery systems, but also delayed release systems. 5-Fluorouracil was taken as a model drug and β-CD as the carrier in this study. Series prodrugs of 5-FU was prepared through the preparation of reactive 5-FU derivatives containing carboxyl group and coupling to hydroxyl groups of CD. The structures of the conjugates were charactered by using IR, UV–vis, ESI-MS, 1H, 13C-NMR spectra, elemental analyses, and thermal analysis. In vitro hydrolysis behavior in aqueous solution and in rat gastrointestinal tract contents of the conjugates were also investigated. The main content of this dissertation includes following aspects: 1. The preparation of 5-FU derivatives containing carboxyl group: 5-Fluorouracil- acetic acid(FUAC)、3-(5-FU-1)-propionic acid (FUPC)、and 5-(5-FU-1)-valeric acid(FUVC). 2. The coupling of 5-FU derivatives to β-CD: 5-FU was selectively conjugated onto the primary or secondary hydroxyl groups of β-CD through an ester linkage, by the substitution of 6-OTs-β-CD and the activated ester method respectively. For the secondary face conjugation, the degree of substitution(DS) can be controlled by changing the mole ratio of the starting materials(FUAC and β-CD). 3. In vitro release behavior of the conjugates in aqueous solution and in rat gastro- intestinal tract contents of the conjugates were investigated, and the reaction was monitored and analyzed by using UV-Vis and HPLC methods.

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研究背景与目的:近二十年来,抗生素的广泛使用以及一些不当应用导致临床上出现大量的耐药性病原菌,所以不易产生耐药性的抗菌肽就成为目前研究的热点。本课题组此前的研究表明无指盘臭蛙(Odorrana grahami)皮肤抗菌肽具有广谱抗菌活性,但对真核细胞没有毒性,因此有成为新型药物的潜力。本研究采用毕赤酵母真核表达系统来生物合成抗菌肽Odorgrin A和Odorgrin C,为大量获取抗菌肽资源提供技术支撑。 方法:依照Odorgrin A和C的氨基酸序列、采用酵母偏爱密码子分别设计并化学合成了相应的目的基因序列。目的片段从合成质粒上用Xho Ι和EcoR Ι双酶切下后,与经同样限制酶完全酶切pPIC9K载体所获得的两个大片段直接连接,并转化至大肠杆菌DH5α。用PCR扩增、酶切及测序检测,鉴定正确的重组质粒。提取大量表达载体pPIC9K - Odo A和C并使之线性化后经电击法分别转化毕赤酵母(Pichia pastoris)GS115宿主菌,用营养缺陷型筛选、遗传霉素抗性筛选、PCR扩增和测序检测,鉴定并筛选出对G418具高抗性的Odorgrin A和C重组酵母菌。用甲醇对之进行诱导表达,SDS - PAGE电泳及反相层析检测表达产物,并做抑菌活性检测。 成果:PCR扩增、酶切及测序等结果表明表达载体pPIC9K - Odo A和C构建成功。营养缺陷型筛选、遗传霉素抗性筛选、PCR扩增和测序等证实pPIC9K - Odo A和C已整合入酵母基因组中。SDS - PAGE电泳及反相层析结果表明抗菌肽Odorgrin A和C成功地获得了分泌表达。而抑菌活性实验则检测到部分阳性克隆菌诱导分泌表达的抗菌肽Odorgrin A和C都对测试菌的生长具有较高(>94%)的抑制率。 结论:无指盘臭蛙皮肤抗菌肽Odorgrin A和Odorgrin C基因的表达载体都构建成功,并且都在毕赤酵母系统中获得了成功表达。 Background & Objective: In the recent twenty years, a lot of pathogenic bacteria have come forth in clinic with durable trait derived from making use of and abusing the traditional antibiotics. Therefore, studying antimicrobial peptides, not be easy to be invalidated by durable bacteria, are becomimg popular and important. The skin antimicrobial peptides of Odorrana grahami with broad spectrum antibacterial activity and no toxicity to eukaryotic cell, discovered by previous research work of our workgroup, are looked forward to being potential medication. Pichia pastoris expressional system was used for biosynthesis antimicrobial peptides Odorgrin A and Odorgrin C in this study, for producing abundant antimicrobial peptides. Methods: The foreign fragments which included Odorgrin A or Odorgrin C gene according to their amino acid sequence respectively were synthesized based on the biased codon usage of yeast. The DNA fragments, obtained from the plasmids containing them by digested with Xho Ι and EcoR Ι, were directly ligated with the two bigger fragments obtained from the vector pPIC9K by digested with the same restriction enzymes. And then they were transformed into Escherichia coli DH5α to be selected and amplified positive colonies. The recombinants were testified by using PCR amplification, enzymes digestion and sequencing of the foreign fragment. After the expressional vector pPIC9K - Odo A and pPIC9K - Odo C were linearized, they were transformed into Pichia pastoris GS115 strain by the electroporation. Then the positive colonies which were of the highest geneticin resistant were selected through auxotrophic screening, genetic resistant screening, PCR amplification and sequencing of the inserted fragment. Methanol was used to induce the recombinant yeasts to express the foreign gene. SDS-PAGE electrophoresis, reversed phase chromatography and antibacterial activity experiment were used to testify the expressional products. Results: The evidences of PCR, enzymes digestion and sequence analysis confirmed that the expressional vector pPIC9K - Odo A and pPIC9K - Odo C have been constructed correctly. The results of auxotrophic screening, of genetic resistant screening, of PCR and sequencing of the foreign fragment showed that Odorgrin A and Odorgrin C gene have been homologous integrated with the Pichia pastoris genome. And it was also testified that antimicrobial peptides Odorgrin A and Odorgrin C have been expressed successfully by using SDS - PAGE electrophoresis, reversed phase chromatography and antibacterial activity experiment. Conclusion: The expressional vector of the skin antimicrobial peptides Odorgrin A and Odorgrin C gene of Odorrana grahami have been constructed correctly and both of the genes have been expressed successfully in Pichia pastoris system in this study.

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Double-stranded RNA (dsRNA) is a virus-associated molecular pattern which induces antiviral innate immune responses and RNA interference (RNAi) in mammals. In invertebrates, RNAi phenomenon has been widely studied, but dsRNA-induced innate immune response is seldom reported. In the present study, two different dsRNAs specific for green fluorescent protein (GFP) and the putative D1 protein of photosystem II (NoPSD) from Nannochloropsis oculata, were employed to challenge Chinese mitten crab Eriocheir sinensis. The temporal changes of phenoloxidase (PO), acid phosphatase (ACP), superoxide dismutase (SOD) and malondialdehyde (MDA) content, as well as the mRNA expression of some immune-related genes were examined in order to estimate the effect of dsRNAs on the innate immunity of E. sinensis. The activities of PO, ACP and SOD significantly increased after dsRNA treatment, whereas malondialdehyde (MDA) content did not change significantly. Among the examined genes, only the mRNA expression of EsALF, an antibacterial peptide in E. sinensis, was significantly up-regulated (about 5 fold, P < 0.05) at 12 h after dsRNA treatment, while no significant expression changes were observed among the other immune genes. The increase of PO, ACP and SOD activities, and mRNA expression level of EsALF after dsRNA stimulation indicate that phenoloxidase, hydrolytic enzyme, antioxidation and EsALF were involved in dsRNA-induced innate immunity, suggesting that broad-spectrum immune responses could be induced by dsRNA in E. sinensis. (C) 2009 Elsevier Ltd. All rights reserved.

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Anti-lipopolysaccharide factor (ALF) represents one kind of basic proteins, which binds and neutralizes LPS and exhibits strong antibacterial activity against Gram-negative R-type bacteria. The ALF gene of Chinese mitten crab Eriocheir sinensis (Milne Edwards, 1853) (denoted as EsALF) was identified from haemocytes by expressed sequence tag (EST) and PCR approaches. The full-length cDNA of EsALF consisted of 700 nucleotides with a canonical polyadenylation signal-sequence AATAAA, a polyA tail, and an open-reading frame of 363 bp encoding 120 amino acids. The high similarity of EsALF-deduced amino acid sequence shared with the ALFs from other species indicated that EsALF should be a member of ALF family. The mRNA expression of EsALF in the tissues of heart, gonad, gill, haemocytes, eyestalk and muscle was examined by Northern blot analysis and mRNA transcripts of EsALF were mainly detected in haemocytes, heart and gonad. The temporal expression of EsALF in haemocytes after Vibrio anguillarum challenge was recorded by quantitative real-time RT-PCR. The relative expression level of EsALF was up-regulated rapidly at 2 h post-injection and reached 3-fold to that in blank group. After a drastic decrease to the original level from 4 to 8h, the expression level increased again and reached 4-fold to that in the blank group at 12 h post-injection. The genomic DNA sequence of EsALF gene consists of 1174bp containing three exons and two introns. The coding sequence of the EsALF mature peptide was cloned and expressed in Escherichia coli BL21(DE3)-pLysS to further elucidate its biological functions. The purified recombinant product showed bactericidal activity against both Gram-positive (G(+)) and Gram-negative (G(-)) bacteria, which demonstrated that the rEsALF was a broad-spectrum antibacterial peptide. All these results indicated that EsALF was an acute-phase protein involved in the immune responses of Chinese mitten crab, and provided a potential therapeutic agent for disease control in aquaculture. (c) 2007 Elsevier Ltd. All rights reserved.

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Antimicrobial peptides are important components of the host innate immune responses by exerting broad-spectrum microbicidal activity against pathogenic microbes. The first mollusk big defensin (designated AiBD) cDNA was cloned from bay scallop Argopecten irradians by expressed sequence tag (EST) and rapid amplification of cDNA ends (RACE) techniques. The scallop AiBD consisted of 531 nucleotides with a canonical polyadenylation signal sequence AATAAA and a poly(A) tail, encoding a polypeptide of 122 amino acids. The high similarity of AiBD deduced amino acid sequence with big defensin from Tachypleus tridentatus and Branchiostoma belcheri tsingtaunese indicated that AiBD should be a member of big defensin family. The expression of AiBD in various tissues was measured by using Northern blotting analysis. mRNA transcripts of AiBD could be detected in haemocytes of unchallenged scallops. The temporal expression of AiBD in haemolymph after Vibrio anguilarum challenge was recorded by quantitative real time PCR. The relative expression level of AiBD in haemolymph was up-regulated evenly in the first 8 h, followed by a drastic increase, and increased 131.1-fold at 32 h post-injection. These results indicated that AiBD could be induced by bacterial challenge, and it should participate in the immune responses of A. irradians. Biological activity assay revealed that recombinant AiBD could inhibit the growth of both Gram-positive and Gram-negative bacteria, and also showed strong fungicidal activity towards the expression host. Recombinant expression of AiBD made it possible to further characterize its functions involved in immune responses, and also provided a potential therapeutic agent for disease control in aquaculture. (c) 2006 Elsevier Ltd. All rights reserved.

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Tellurite glass is proposed as a host for broadband erbium-doped fiber amplifiers because of their excellent optical and chemical properties. A single-mode Er3+-doped tellurite glass fiber with D-shape cladding was fabricated in this work. The characterization of amplified spontaneous emission (ASE) from this newly fabricated Er3+-doped tellurite fibers are exhibited. When pumped at 980 nm, a very broad erbium ASE nearly 150 nm around 1.53 mum is observed. The changes in ASE with regard to fiber lengths and pumping power were measured and discussed. The output of 2 mW from Er3+-doped tellurite fiber ASE source was obtained under the pump power of 660 mW. The broad 1.53 mum emission of Er3+ in tellurite glass fiber can be used as host material for potential broadband optical amplifier and tunable fiber lasers. (C) 2004 Elsevier B.V. All rights reserved.

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We present fabrication and experimental measurement of a series of photonic crystal waveguides and coupled structure of PC waveguide and PC micro-cavity. The complete devices consist of an injector taper down from 3 mu m into a triangular-lattice air-holes single-line-defect waveguide. We fabricated these devices on a silicon-on-insulator substrate and characterized them using tunable laser source. We've obtained high-efficiency light propagation and broad flat spectrum response of photonic-crystal waveguides. A sharp attenuation at photonic crystal waveguide mode edge was observed for most structures. The edge of guided band is shifted about 31 nm with the 10 nm increase of lattice constant. Mode resonance was observed in coupled structure. Our experimental results indicate that the optical spectra of photonic crystal are very sensitive to structure parameters.

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We present fabrication and experimental measurement of a series of photonic crystal waveguides and coupled structure of PC waveguide and PC micro-cavity. The complete devices consist of an injector taper down from 3 mu m into a triangular-lattice air-holes single-line-defect waveguide. We fabricated these devices on a silicon-on-insulator substrate and characterized them using tunable laser source. We've obtained high-efficiency light propagation and broad flat spectrum response of photonic-crystal waveguides. A sharp attenuation at photonic crystal waveguide mode edge was observed for most structures. The edge of guided band is shifted about 31 nm with the 10 nm increase of lattice constant. Mode resonance was observed in coupled structure. Our experimental results indicate that the optical spectra of photonic crystal are very sensitive to structure parameters.

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A kind of novel broad-band superluminescent diodes (SLDs) using graded tensile-strained bulk InGaAs is developed. The graded tensile-strained bulk InGaAs is obtained by changing only group-III trimethyl-gallium source flow during low-pressure metal organic vapor-phase epitaxy. At the injection current of 200 mA, the fabricated SLDs with such structure demonstrate full-width at half-maximum spectral width of 106 nm and the output light power of 13.6 mW, respectively.

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Organic photovoltaic cells with a strong absorption spectrum in the near infrared region were fabricated with the structure of indium tin oxide (ITO)/zinc phthalocynine (ZnPc)/lead phthalocynine (PbPc)/C-60/Al. PbPc has a broad and strong absorption, while the organic films of PbPc/C-60 showed an additional new absorption peak at 900 nm. The absorption in the near infrared region can harvest more photons to invert into photocurrent. Moreover, the introduction of ZnPc thin layer between ITO and PbPc further improved the new absorption peak and the collection of hole carriers at the electrode ITO, which increased the power conversion efficiencies to 1.95% and short-circuit current density to 9.1 mA/cm(2) under AM 1.5 solar spectrum.

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Objective speckle from a stick-on foil is a new approach to applying the objective white light speckle method to in-plane displacement measurements. By a relatively easy technique a thin aluminum foil is mounted onto the specimen surface and a random grating is scratched onto it, yielding high reflectance and fine optical details. After double exposure by a direct recording system without using a lens, the resulting holographic film possesses a broad spatial spectrum and displacement information. Full-field contour maps of equal displacement can be obtained that are of good contrast and high sensitivity and that have a large adjustable measurement range. The method can be applied to practical engineering problems for both plane and developable curved surfaces.