971 resultados para UV-Vis spectra
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本工作较系统地研究了聚苯胺(PAn)的合成、结构及性能。用红外光谱法及溶液~(13)C-NMR方法研究了本征态PAn的链结构。结果表明具有较高电导率样品的分子链上的芳环以1,4-取代结构为主,苯式单元与醌式单元以3:1的比例无规分布。在对本征态链结构的研究基础上,进一步对掺杂态PAn的FTIR、固体~(13)C-NMR、UV-VIS、Raman、ESR及XPS谱进行了讨论和指认。根据掺杂前后的谱图变化指出,质子酸掺杂发生在醌式结构的氮原子上,正电荷及电子的离域化导致苯式单元和醌式单元发生部分氧化还原反应,生成具有一定电荷分布的含有变体苯结构及变体醌结构的长共轭体系。通过宽线~1H-NMR及ESR方法,研究了PAn的电荷传递过程,指出带有自旋的电子是导电的载流子,它通过Heisenberg交换方式在分子链内传递。分子链间的传递在其导电过程中起了重要作用。采用I_2、MoCl_5及BF_3等氧化试剂对PAn进行掺杂,表明PAn可进行氧化还原掺杂,但所得电导率比质子酸掺杂的低,掺杂过程也与之不同。通过考察PAn在不同条件下的电化学行为并结合现场Raman光谱及现场ESR谱的研究,指出PAn循环伏安曲线上的峰1可解释为将纯苯式结构中近四分之一的苯环氧化为苯二胺双自由基结构的反应;峰3则可能是由峰1的氧化产物继续氧化为苯-醌交替结构的反应;峰2可能与在高电位氧化后的产物进一步水解所得到苯醌与对苯二酚的反应及阴离子的嵌入与脱嵌过程有关。还对PAn的结晶性、热稳定性和空气稳定性以及聚合过程中生成的副产物等方面作了一些研究。
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采用(NH_4)_2S_2O_8+HCl体系用化学氧化法首次合成了本征态可溶的聚N-甲基苯胺(PMAn)。系统研究了聚合条件(氧化剂浓度、盐酸浓度、单体浓度)对单体(MAn)聚合行为及所得产物结构,性质的影响,确定了合成较好性能PMAn的最佳聚合条件,即氧化剂与单体摩尔比为2:1,单体浓度为0.5M盐酸浓度为0.1-1.0M。利用FTIR,~(13)C-NMR,XPS及元素分析等手段研究了本征态PMAn的链结构,结果表明PMAn中单体单元以1.4-方式连接形成线性头--尾结构,链上同时存在苯、醌两种结构单元,醌式含量随氧化剂浓度增大或I_2处理而提高。PMAn可由酸碱进行可逆的掺、反掺杂,其掺杂度受PH值影响,在PH=0~4范围内随PH值的降低而增大。PMAn的质子酸掺杂过程在本质上是分子链了质子化过程与所用酸的阴离子无关。FTIR,UV-VIS,ESR,XPS等表征结果说明,掺杂后链上未偶电子显著增加,电子和正电荷高度离域化,形成了大共轭体系。PMAn的电导率随掺杂度的提高而增大,最高可达10~(-3) s/cm,电导率的增大过程与阳离子自由基的增加及其离域化程度的提高过程相一致。苯胺类聚合物的电导率随压力增大而增大,显示了电子导电特性,PMAn的导电载流子是离域化的阳离子自由基。电导率的温度依赖性关系说明电子传输过程符合三维FIT模型。PMAn具有良好的环境稳定性和热稳性,基本征态在一系列有机溶剂中可溶,在酸性介质中显示出电活性。
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本文选择不同配体(苯酚类和迭氮)通过Cr(III)(TPP)Cl (Al)的氧化还原取代,分别合成了四个新的铬(III)卟啉配合物,Cr(TPP)N_3P_Y(B_1), P-O_2NC_6H_4OCr(TPP)·THF (C1), P-CH_3OCoH_4OCr(TPP)·THF (D1), Cr(TPP)OC_6H_5·THF (E1)。通过元素分析,红外光谱、~1H NMR、ESR、MS和UV-Vis等分析、表征,确认了以上四种化合物。B1单晶进行了X-射线分析,得其晶体结构和分子结构,从而进一步证实了B1的组成。在CH_2Cl_2或C_6H_6中,氮气保护下,用PhIO直接氧化以上五种铬(III)卟啉配合物,合成并分离出了相应的高价氧络铬卟啉配合物,(PhI) O=Cr(▽)(TPP)Cl (A2), (PhI) O=Cr(▽)(TPP)N_3, (B2), P-O_2NC_6H_4O Cr(▽)(TPP) (1/2IPh) (C2), P-CH_3OC_6H_4O Cr(▽)(TPP) (1/2IPh) (D2), PhIO- Cr(IV)(TPP) (OC_6H_5)·P_Y (E2)。通过研究其元素组成,IR、UV-Vis、ESR、MS等分析,确定了以上五种化合物的组成。基中PhI和P_Y分子的位置尚无法确定。这两类高价氧络铬卟啉,是继右淑珍等第一次得到P450模型化合物的活性中间体-氧络铬(▽)四苯基卟啉对硝基苯甲酸配合物后,又一次得到的苯酸类和迭氮氧络铬卟啉配合物。不同的是,氧络铬(▽)卟啉配合物中都各有PhI分子,化合物E2是第一次得到的关键氧络铬(IV)卟啉配合物,类似于PhIO-Mn~(IV)(TPP)(P-H_2N C_6H_4 CO_2)。高价氧络铬卟啉配合物不稳定,室温下分解,暴露在空气中同时发生分解和还原。不过低温下比较稳定。在CH_2Cl_2或C_6H_6中,我们研究了上述五种氧络铬及Cr(TPP)ClPhIO对碳氢化合物和DNA碱基的氧化反应。不同摩尔比的PhIO-Cr(TPP)Cl对环已烷的氧化给出相同的产物,但转化率和产物分布不同。Al-PhIO和C_2-PhIO体内对碱基胞嘧啶,胸腺嘧啶,腺嘌呤的氧化反应呈阳性,氧化产物中都有尿素CO(NH_2)_2,其中胸腺嘧啶的氧化产物中含有CH_3CO-或CH_3CHOH。这说明氧络铬卟啉配合物能够氧化DNA碱基。氧络铬卟啉具有较高的氧化活性和立体选择性。比较不同轴向配体的氧络铬卟啉的氧化活性,其大小次序正好与其轴向配体的配位能力次序一致。这是由于轴向配体的给电子能力越强,通过中心离子铬向其周围转移的电荷就越多,导致氧络键的强度减弱,即其活性增加。上述研究结果表明,铬(III)卟啉配合物是P-450的较好的模型化合物,氧络铬卟啉配合物是其活性中间体。同时该研究结果支持了Groves等提出的定居卟啉配合物催化氧化机理。
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本工作对三种极化非线性光学(NLO)高聚物进行了研究。1)有机染料掺杂型NLO高聚物:把分散红(DR1)和对硝基苯胺(p-NA)掺杂于无定型高聚物中,用旋涂法成膜,在掺杂高聚物Tg以上,用电晕极化法使薄膜中的染料分子取向。研究了电晕极化条件对取向效果的影响。具有高Tg的极化膜显示了好的取向稳定性;2)主链或侧链含生色基团的NLO高聚物:分散红以共价键接枝在高分子侧链或对硝基苯胺接枝在高分子主链。用UV-vis光谱法和偏振IR光谱法表征了NLO高聚物极化过程。同染料掺杂高聚物比较,主链型高聚物具有较好的取向稳定性。3)交聚型NLO高聚物:4-(2,3-二羟基丙氧基)-4'-硝基偶氮苯与六亚甲基二异氰酸酯的缩二脲进行电场极化交联反应。在较短时间内得到完全交联的NLO聚合物材料。采用变温FT-IR光谱及DSC对不同温度的交联过程进行了详细的研究。在适当的预聚温度和时间以及极化温度和电压等固化条件下,测得极化膜的d_(33)值。
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采用射频磁控反应溅射法结合热退火处理技术制备纳米硅镶嵌氮化硅(nc-Si/SiNx)复合薄膜。通过X射线能谱(EDS)、红外光谱(IR)、X射线衍射(XRD)及紫外-可见吸收光谱(UV-vis)的测定,对薄膜进行了组分、键合状态、结构及光学带隙的表征。采用皮秒激光运用单光束Z扫描技术开展了对该复合薄膜的非线性光学性质的研究,测得其三阶非线性折射率系数和非线性光吸收系数分别为10~(-8)esu和10~(-8)m/W量级,并将薄膜这种三阶光学非线性增强的原因归因于量子限域效应。
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报道了选用厚度为0.05mm的不锈钢箔作衬底,B掺杂P型氢化纳米硅作窗口层,制备成功开路电压和填充因子分别达到0.90V和0.70的nip非晶硅基薄膜单结太阳电池.UV-VIS透射谱和微区Raman谱证实所用p层具有典型氢化纳米硅的宽能隙和含有硅结晶颗粒的微结构特征.明确指出导致这种氢化纳米硅能隙展宽的物理机制是量子尺寸效应.
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用PECVD方法,以固定的甲烷硅烷气体流量比([CH4]/[SiH4]=1.2)和不同的氢稀释比(RH=[H2]/[CH4+SiH4]=12,22,33,102和135)制备了一系列的氢化非晶硅碳合金(a-SiC:H)薄膜.运用紫外-可见光透射谱(UV-VIS)、红外吸收谱(IR)、Raman谱以及光荧光发射谱(PL)测量研究了氢稀释和高温退火对薄膜生长和光学特性的影响.实验发现氢稀释使薄膜光学带隙展宽(从1.92到2.15 eV).高氢稀释条件下制备的薄膜经过1250℃退火后在室温下观察到可见光发光峰,峰位位于2.1 eV.结合Raman谱分析,认为发光峰源于纳米硅的量子限制效应,纳米硅被Si-C和Si-O限制.
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本论文由四部分组成。第一部分报道了佛手参提取物的化学成分研究,建立了活性成分含量测定的高效液相测定和指纹图谱研究,采用液质联用技术鉴定了主要色谱峰;第二部分报道了丹参及其复方制剂的特征图谱研究;第三部分探讨了两面针生物碱的电喷雾质谱裂解规律,并采用液质联用技术分离鉴定了提取物中的多种生物碱。第四部分概述了液质联用在药物代谢研究中的运用。 第一部分包括第一、第二和第三章。第一章针对佛手参(Gymnadeniaconopsea)块茎的甲醇提取物,采用大孔树脂和反相硅胶柱层析等各种分离方法,共分离鉴定出4 个化合物,通过波谱分析将它们的结构确定为dactylorhin B (1)、loroglossin (2)、dactylorhin A (3)和militarine (4)。这4 个化合物均是首次从佛手参中分离得到的琥珀酸葡萄糖苷类成分。第二章采用高效液相色谱法对西藏、四川、河北、青海和尼泊尔等不同地区产的十个佛手参样品进行腺嘌呤核苷和对羟基苯甲醇的定量分析,结果表明这2 个成份可视为佛手参的特征成分,但也注意到产地不同该2 个特征成分的含量也有所不同。第三章采用标准中药指纹图谱相似度计算软件,以10 个佛手参样品HPLC 图谱的平均值为相似性评价对照模板,对10 个样品进行了相似度评价,并经液质联用分析指认了7 个共有峰,分别为腺嘌呤核苷(1)、对羟基苯甲醇(2)、对羟基苯甲醛(3) 、dactylorhin B(4) 、loroglossin(5)、dactylorhin A(6)和militarine(7)。 第二部分包括第四、第五、第六和第七章。第四章运用电喷雾质谱检测了对照药材和五个不同产地的丹参药材中脂溶性和水溶性成分,系统地探讨了多种成分的电喷雾质谱规律,并以对照药材为标准建立了特征指纹图谱。五个产地的药II材通过与对照药材相对比,采用聚类分析的方法,得到了定性的鉴别与判断。并采用液质联用技术对丹参药材提取液中的化学成份进行分析,推测了九个特征峰,并对六样品的液相色谱图进行了聚类分析。第五章探讨了三七皂苷的电喷雾质谱电离和裂解规律,并采用电喷雾质谱法对三七标准药材,血通片中的皂苷成分进行了分析。第六章运用电喷雾质谱研究复方丹参片提取液的特征图谱,并和单味药材丹参和三七的特征图谱进行了对比研究。并运用HPLC-ESI MSn 分析鉴定了复方丹参片提取液中的化学成分,推测了12 个色谱峰。第七章总结了电喷雾质谱和液质联用技术在丹参药材,三七药材及复方丹参制剂中的运用的优势和局限性。 第三部分(第八章)研究了两面针生物碱中二氢白屈菜红碱(1)、二氢两面针碱(2)、8-酮基二氢白屈菜红碱(3)、8-丙酮基二氢两面针碱(4)、两面针碱(5)、和1,3-二(8-二氢两面针碱)丙酮(6)等六个苯并菲啶型生物碱的电喷雾质谱裂解规律,其中二氢两面针碱和二氢白屈菜红碱,8-丙酮基二氢两面针碱和8-酮基二氢白屈菜红碱是两对二个甲氧基分别在C-9 和C-10,C-10 和C-11 的同分异构体。实验结果表明,在相同的碰撞能下,这类位置异构体的ESI MS2 质谱二级碎片离子的相对峰度存在很大差异,这可以用于区分该类同分异构体,采用液-质联用可以对两面针的总生物碱提取物中的这些同分异构体加于区分。同时在本实验采用的液相色谱条件下,多种生物碱得到较好的分离,通过和对照品的保留时间,紫外吸收光谱及电喷雾质谱图对照,鉴定了11 个主要色谱峰。 第四部分(第九章)对液质联用技术在药物代谢中的运用进行了综述。 This dissertation consisted of four sections. The first two sections elaborated thephytochemical investigation of the rhizomes Gymnadenia conopsea R. Br., methoddevelopment for rapid identifying and qutifying the chemical condtituent of thistibetant medicine, and the chemical fingerprint analysis of rhizomes of G. conopsea,Salviae miltiorrhiza and P. notoginseng. The third section studied the fragmentationmechanism of six alkaloids from Zanthoxylum nitidium and method development forrapid identifying varieties of alkaloids from the extract of this herbal medicine. Thefourth section reviewed HPLC- MS method in drug metabolism studies. The first section consisted of chapters 1, 2, 3. Chapter 1 elaborated the phytochemicalinvestigation of Gymnadenia conopsea R. Br. Four succinate derivative esters wereisolated from the methanol extract of the rhizomes of G. conopsea through repeatedcolumn chromatography on normal and reversed phase silica gel, their structures weredetermined by ESI-MS, 1D and 2D NMR evidence. They were firstly discoveredfrom this species. In chapter 2, a high-performance liquid chromatography.diodearray detection (HPLC-DAD) method has been firstly developed for quantitation oftwo characteristic constituents, adenosine and 4-hydroxybenzyl alcohol, from theextract of rhizomes of G. conopsea. All 10 samples of G. conopsea contained differentamount of adenosine and 4-hydroxybenzyl alcohol. Adenosine and the4-hydroxybenzyl alcohol can be applied in identification and quality control for theroots of G. conopsea. In chapter 3, a high-performance liquid chromatography.diodearray detection.tandem mass spectrometry (HPLC-DAD-MSn) method has been firstly developed for chemical fingerprint analysis of rhizomes of G. conopsea andrapid identification of major compounds in the fingerprints. Comparing the UV andMS spectra with those of authentic compounds, seven main peaks in the fingerprintswere identified as adenosine, 4-hydroxybenzyl alcohol, 4-hydroxybenzyl aldehyde,dactylorhin B, loroglossin, dactylorhin A and militarine. The Computer AidedSimilarity Evaluation System for Chromatographic Fingerprint of TraditionalChinese Medicine (CASES) was employed to evaluate the similarities of 10 samplesof the rhizomes of G. conopsea collected from Sichuan, Qinghai and Hebei provincesand Tibet autonomous region of China, and Nepal. These samples from differentsources had similar chemical fingerprints to each other. The second section consisted of chapters 4, 5, 6 and 7. In chapter 4,both thecharacteristic spectra of liposoluble tanshinones and aqueous-soluble salvianolic acidswere established by the electrospray ionization mass spectrometry (ESI MS)technique and the differences between standard and crude rhizomes of Salviaemiltiorrhiza Bge. from 5 sources were analyzed. The law of electrospray ion trap mass(ESI ITMS) of typical tanshinones and salvianolic acids is studied.The analysis of the chemical constituent of rhizomes of Salviae miltiorrhiza Bge. byliquid chromatography coupled with mass spectrum (LC/MS) technique wasestablished,and the distances among standard herb and crude herb from 5 sourceswere calculated by clustering analysis. According the DAD spectra and MS2 data,9tanshinones could be speculated. In chapter 5, the character spectra of total saponinsin P. notoginseng extracts were established by ESI ITMS and selective ion monitoring(SIM) technology. The law of notoginsenosides by ESI MS2 was studied. In chapter 6,the characteristic spectra of Compound Danshen Tablet established and compared byESI-MS and HPLC/DAD/MS, 6 known tanshinones and 3 saponins were speculated.In chapter 7, the advantage and disadvantage of the strategy, using the ESI ITMS andLC/MS techniques for study of characteristic spetra of danshen and Compound Danshen Tablet, were summerized. The third section (chapter 8) studied the fragmentation mechanism of six alkaloids,dihydronitidine, dihydrochelerythrine, 8-acetonyl dihydronitidine,8-acetonyldrochelerythrine, nitidine and 1,3-bis (8-dihydronitidinyl)-acetone, by ESIMSn. Tandem mass spectrometry experiments indicated that different substitutionsites of the methoxyl groups at C-9 and C-10 or at C-10 and C-11 determined thedifferent abundances of the MS2 fragmentation ions using the same collision energy.According to the different abundances of MS2 product ions, positional isomericbenzo[c] phenanthridine alkaloids can be differentiated. Moreover, ten constituents inthe crude alkaloids extract from the roots of Zanthoxylum nitidium were rapidlyidentified by high-performance liquid chromatography coupled with tandem massspectrometry (HPLC-MSn), through comparing the retention times and ESI MSn spectra with the authentic standards. The fourth section (chapter 9) is a review on HPLC-MS method development in drug metabolism studies.
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环糊精(Cyclodextrins, CDs)经化学修饰后可以得到各种类型的衍生物,不仅可以扩展其原有的键合能力,而且还可以改变其选择性,是当代超分子化学的一个研究热点。环糊精第二面的仲羟基比第一面的伯羟基有着更好的催化性能,第二面的选择性修饰将产生更多有价值的衍生物,可用于催化、酶模拟、手性识别等方面。 取代苯甲酰基修饰环糊精对顺式环辛烯(cis-cyclooctene)光异构化反应有非常重要的影响作用,苯环上取代基的性质和取代位置与产物的%ee值和对映体构型之间存在某种内在联系。有目的地选择适宜取代基,设计、合成新型环糊精光增感剂, 有可能按预定目的得到更高%ee值的反式环辛烯;同时,取代苯甲酰基修饰环糊精对cis-cyclooctene光异构化的增感机理有待于进一步阐明。 本论文工作对环糊精的化学修饰以及超分子体系对cis-cyclooctene不对称光异构化反应方面的进展进行了调研。合成了一系列单-6-位取代苯甲酰基修饰环糊精,用于cis-cyclooctene光异构化增感反应,并用圆二色光谱滴定法研究这些环糊精衍生物与cis-cyclooctene的相互作用,以探索光增感反应机理。在此基础上,探讨了环糊精第二面的选择性修饰方法。内容主要包括: 1. 简要介绍了超分子化学的概况,并对环糊精的选择性修饰方法和超分子体系对cis-cyclooctene不对称光异构化反应的主要成果和最新进展进行了评述。 2. 合成了12种单-6-O-(取代苯甲酰基)-β-环糊精,其中10种为新化合物。采用紫外光谱、红外光谱、核磁共振波谱以及质谱等手段对化合物的结构进行了表征。 3. 探索了直接选择性修饰环糊精第二面的便捷新方法。用取代苯甲酰咪唑酯为酰化试剂,0.2M碳酸盐缓冲溶液(pH=9.9)作催化剂,能够有效地活化2-位仲羟基,对环糊精第二面进行选择性修饰,此方法既简便又经济;同时,发现取代苯甲酰基能够在β-CD第二面的2-位、3-位羟基间相互迁移。 4. 用单-6-O-(取代苯甲酰基)-β-环糊精作光增感剂,对cis-cyclooctene光异构化反应进行研究。实验结果证明:取代苯甲酰基上的取代基性质、位置、长度对反应的对映选择性有很大影响;此外,反应体系溶剂极性对产物的%ee值和对映体构型也有重大影响。用单-6-O-(3-甲氧苯甲酰基)-β-CD作增感剂,cis-cyclooctene光异构化反应产物(R)-trans-cyclooctene的对映选择性为45.8%ee,是到目前为止取得的最好对映选择性。 5. 采用圆二色光谱滴定法研究环糊精衍生物与cis-cyclooctene的相互作用,计算包结物的平衡常数,研究包结物的相对稳定性,为探索光增感反应机理提供基础。我们猜测:电子效应对cis-cyclooctene光异构化反应的影响,可能比取代基位置对反应的影响更大,借助电子效应有希望获得更高的%ee值。 Cyclodextrins can be subjected to diverse modifications to give a wide variety of cyclodextrin derivatives, which could not only extend their original molecular binding ability, but also alter their molecular selectivity. Therefore, cyclodextrin chemistry is currently a significant topic in supramolecular chemistry. The more open secondary hydroxyl side of CDs is stated to be catalytically very important, modifications of this face are believed to produce valuable derivatives for catalysis, enzyme mimic, chiral discrimination, etc. Mono-6-O-(substituted benzoyl)-β-CDs as novel supramolecular photosensitizing hosts have recently excited considerable attention in photochirogenesis. The supramolecular photosenstization of cis-cyclooctene mediated by them gave chiral trans-cyclooctene, enantiomeric excess of which was critically affected by the substituent introduced to the sensitizer moiety. In order to enhance the photoenantiodifferentiating ability, and elucidate the origin mechanisms of substituent-dependent enantioselectivity, in this work a series of mono-6-O-(substituted benzoyl)-β-CDs have been synthesized, and applied for enantiodifferentiating photoisomerization of cis-cyclooctene. The major contents are as follows: 1. The general aspects of supramolecular chemistry were descibed briefly. The new progress and important achievements on methods of selective modification of cyclodextrin and supramolecular enantiodifferentiating photoisomerization of cis-cyclooctene were reviewed. 2. Twelve mono-6-O-(substituted benzoyl)-β-CDs including ten novel compounds have been synthesized. Their structures have been characterized by using UV-vis, IR, NMR and MS methods. 3. A new convenient strategy for direct acylation of β-cyclodextrin on the secondary hydroxyl face was achieved by using the combination of N-benzoylimidazole and carbonate buffer in DMF, and the acyl migration between the C-2 and C-3 hydroxyl groups of β-cyclodextrin was found. 4. Experiments using mono-6-O-(substituted benzoyl)-β-CDs as chiral sensitizing hosts for mediating the enantiodifferentiating photoisomerization of cis-cyclooctene, were carried out. The results indicate that enantiomeric excess was critically affected, or even switched in sign, by the substituent introduced to the sensitizer moiety, and polarity of solvent. Using mono-6-O-(3-methoxybenzoyl)-β-CD as chiral sensitizing host, (R)-trans-cyclooctene was obtained in up to 45.8% enantiomeric excess, which is the highest value ever reported for supramolecular photochirogenesis with analogous hosts. 5. The conformational variation of these modified CDs and their complexation behaviors with cis-cyclooctene were examined by circular dichroism spectroscopy in water-methanol mixed solvents, which reveal that the orientation of chromophore was highly sensitive to the type, position and length of the introduced substituents. In the end, the complex stability constants(Ks) were calculated, and the mechanisms of reaction were discussed. Maybe, electronic effects are more important than positions of substituents for mediating the enantiodifferentiating photoisomerization of cis-cyclooctene.
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近二十多年来,基于对臭氧层衰减、紫外线B(UV-B)增强的担心,研究者希望了解到紫外线辐射对不同作物的影响情况,增强UV-B辐射条件下是否对作物的生长发育、产量质量构成威胁。在本试验中,我们首先探讨了双子叶作物黄瓜(Cucumis sativus)和大豆(Glycine max)对不同紫外波段的生物效应[分别为B-UVA(315-400 nm),N-UVA(315-340 nm),B-UVB(275-400 nm)和N-UVB(290-340 nm),UV-(>400nm)作对照]。我们观察到所有的UV波段处理都使黄瓜和大豆的生长受到抑制,并且细胞受到不同程度的氧化伤害;UV波段处理的作用效果与不同波段的紫外有效生物辐射剂量有关。处理差异在UV-B波段内部和UV-A波段内部同样存在。植物生长UV辐射公式(BSWF)能很好的预测本试验UV-B波段内的平均植物效应,但不能预测UV-A波段的植物效应。短波UV-A的生物作用强于长波UV-A。光合色素的变化与UV波谱差异和种间差异有关。在高的紫外/可见光背景下,UV-A处理同UV-B同样导致光合色素的降低,但黄瓜类胡萝卜素/叶绿素比例升高。与其他研究者的试验结果比较后,我们认为紫外线B辐射的生物效应一致性很高,但紫外线A波段的生物学效应存在较大争议。因此我们在本试验的基础上仅进行荞麦[苦荞(Fagopyrum tataricum Gaertn.)和甜荞(Fagopyrum esculentum Moench.)]对紫外线B波段的响应研究。 我们对苦荞品种-圆籽荞进行了连续两个生长季节的大田半控制试验以观察UV-B辐射对苦荞生长、发育、产量及叶片色素的影响;试验小区进行降低UV-B、近充足UV-B和增强UV-B辐射处理。我们的试验表明在不同强度UV-B辐射下苦荞的生长、地上部生物量积累及最终产量都有所下降,但苦荞的发育加快;当前条件下的日光紫外线B辐射对植物生长和产量也造成负面影响。植物光合色素被日光及增强UV-B辐射降低;UV化合物及卢丁含量在中低剂量的UV-B辐射强度下显著升高,但在高剂量的增强UV-B辐射下短期升高后迅速下降。我们的试验表明苦荞是一个对UV-B高度敏感的作物。苦荞对UV-B的敏感性与UV-B剂量、外界环境因素及生长季节有关。 单个苦荞品种的试验结果使我们认识到外界UV-B辐射已经对苦荞生长发育构成逆境条件,未来全球气候变化条件下增强紫外线B辐射可能使其处于更不利的生长环境中。因此我们有进行了多个种群进行UV-B响应观察并筛选耐性种群。我们对15个苦荞种群进行增强UV-B辐射处理(6.30 kJ m2 UV-BBE,模拟当地25%的臭氧衰减),我们观察苦荞UV-B辐射效应存在显著的种内差异,UV-B辐射对多数种群具有抑制作用,但对一些种群还有刺激作用。我们采用主成分分析方法与作物UV-B响应指数(RI)来评价苦荞作物UV-B辐射耐性。我们发现作物的UV-B耐性不仅与其原产地背景UV-B强度有关,而且与作物相对生长效率、次生代谢产物含量(如卢丁)及其他因素有关。我们观察到苦荞伸展叶总叶绿素变化与UV-B耐性成正相关;室内苦荞幼苗的UV-B辐射致死试验表明:苦荞种群死亡率与其UV-B耐性成负相关。 此外,我们对甜荞的UV-B辐射响应也进行了初步研究。选取美姑甜荞、巧家甜荞和云龙甜荞进行5个梯度的增强UV-B辐射室外模拟试验。我们观察到UV-B辐射显著降低了甜荞的生长、生物量及产量;并严重影响了甜荞的生殖生长,降低了花序数、种子数和结实率;并且UV-B辐射对甜荞的抑制作用存在显著的剂量效应。三种甜荞品种存在显著的种内差异,其中美姑品种UV-B耐性最强,且膜脂受UV-B辐射氧化伤害最小,这与该品种UV-B辐射下较高的GR酶活性、APX酶活性和PPO酶活性、以及含量更高的抗坏血酸有关。甜荞的次生代谢也受到增强UV-B辐射的影响,其香豆酰类化合物在UV-B辐射下升高显著,而槲皮素含量也在高剂量UV-B辐射下有所增加;卢丁含量依赖UV-B辐射剂量而变化,中低剂量UV-B辐射下其卢丁含量逐渐升高,但在高剂量辐射下逐渐下降。 通过对生长在高海拔地区的荞麦作物(苦荞和甜荞)进行的室外研究,我们认识到作物不同品种存在很大的耐性差异,这就为UV-B耐性育种创造了有利条件。进一步加大荞麦种质资源筛选力度并深入认识荞麦抗性机理,在此基础上通过杂交或其他基因融合手段培育抗性品种,对高剂量UV-B辐射地区的荞麦产量的提高将起到重要推动作用,并使荞麦生产能有效应对未来全球气候变化条件下UV-B辐射可能升高的威胁。 During last few decades, due to concern of ozone layer depletion and enhancement of ultraviolet B radiation(UV-B, 280-315 nm), the agronomist want to know the responses of different crop species to UV-B. In the first experiment of our study, the effect of different UV band [B-UVA(315-400 nm), N-UVA(315-340 nm), B-UVB(275-400 nm), N-UVB(290-340 nm)and UV-(>400nm, as control)] on the cucumber(Cucumis sativus)and soybean(Glycine max)were investigated in growth room. Spectra-dependent differences in growth and oxidation indices existed within UV-A bands as well as UV-B bands. The general biological effects of different band were UV- < B-UVA< N-UVA<N-UVB<B-UVB. The plant growth biologically spectra weighting function(BSWF)matched well with average plant response in UV-B region, but not in UV-A region. Shorter UV-A wavelength imposed more negative impact than longer UV-A wavelength did in both species. The effect on photosynthetic pigment was related to different UV bands and different species. The photosynthetic pigment content was decreased by UV-A spectra as well as UV-B spectra. In comparison with the results of previous studies, we found that the wavelength-dependent biological effect of ultraviolet B radiation has high consistency, but the biological effect of ultraviolet-A radiation was inconsistent. We narrow our following study on the effect of ultraviolet B radiation on the buckwheat(tartary buckwheat and common buckwheat). The tartary buckwheat(Fagopyrum tataricum Gaertn.)cultivars Yuanziqiao was grown in the sheltered field plots for two consecutive seasons under reduced, near-ambient and two supplemental levels of UV-B radiation. The crop growth, photosynthetic pigments, total biomass, final seed yield and thousand-grain weight were decreased by near-ambient and enhanced UV-B radiation, while crop development was promoted by enhanced UV-B radiation. Leaf rutin concentration and UV-B absorbing compound was generally increased by UV-B with the exception of 8.50 kJ m-2 day-1 supplemental levels. Our results showed that tartary buckwheat is a potentially UV-B sensitive species. Study on one cultivars showed that ambient solar radiation had present a stress to tartary buckwheat. This makes it necessary to observe the UV-B response of many cultivars and screen tolerant cultivars. Fifteen populations of tartary buckwheat were experienced enhanced UV-B radiation simulating 25% depletion of the stratospheric ozone layer in Kunming region, and plant responses in growth, morphology and productivity were observed. Principal components analysis(PCA)was used to evaluate overall sensitivity of plant response to UV-B as well as response index. The different populations exhibited significant differences in responses to UV-B. The photosynthetic pigments of young seedlings were also affected significantly under field condition. On the other hand, the healthy seedlings of different populations were exposed to the high level of UV-B radiation in growth chambers to determine the plant lethality rate. The plant tolerance evaluated by multivariate analysis was positively related to total plant chlorophyll change, but negatively related to lethality rate. In other hand, the UV-B responses of the other important cultivated buckwheat species, common buckwheat(Fagopyrum esculentum Moench.), were also studied preliminarily. Three widespread cultivated variety(Meigu, Qiaojia and Yunlong cultivars)were provided with five level of enhanced UV-B radiation outdoors. We observed that the crop growth, development and production were significantly decreased, and reproductive production, like anthotaxy number, seed number and seed setting ratio, was also decreased. Dose-dependent inhibition effect caused by enhanced UV-B radiation also existed in common buckwheat. Significant intraspecific difference existed in those three cultivars. The Meigu cultivars with dwarfed growth and lower production have highest UV-B tolerance as well as lowest damage in cell membrane, this could be associated with profound enhancements of glutathione reductase(GR)activity, ascorbate peroxidase activity and polyphenol oxidase activity as well as higher ascorbic acid concentration. The secondary metabolism was also affected by UV-B radiation, with profound elevation of coumarin compound and moderate increase of quercetin concentration. Rutin concentration was peaked in 5kJ m-2 UV-B. The contrasting effect of UV-B radiation on different populations indicated that there existed abundant genetic resources for selecting tolerant populations of common and tartary buckwheat. Much effort needed be pose on screening of buckwheat germplasm and clarification of mechanism of buckwheat tolerance to UV-B. On this base the tolerant cultivars could be bred by hybridization and other gene transfusion method, this would help increase buckwheat yield in high ambient UV-B region and counteract the effect of possible enhanced UV-B radiation in future.
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A modified solution method, successive ionic layer adsorption and reaction(SILAR), was applied to prepare transparent zinc oxide(ZnO) film on glass substrate at (125±5) ℃ in mixed ion precursor solution. The surface morphology and crystallizations of films were analyzed by field emission scanning microscopy(FESEM) and X-ray diffraction(XRD), respectively. The optical properties of the films were studied by ultraviolet visible(UV-Vis)spectroscopy. The results show that the obtained samples are polycrystallin...中文文摘:采用一种改进的液相成膜技术——连续离子层吸附与反应(SILAR)法,用锌氨络离子[Zn(NH3)4]2+溶液作为独立的前驱体溶液,以载玻片为衬底,在(125±5)℃的温度下沉积出致密、透明的ZnO薄膜。分别用冷场发射型扫描电镜(FESEM)和X射线衍射(XRD)分析了薄膜样品的表面形貌和结晶状态,用紫外-可见分光光度计(UV-Vis spectroscopy)研究了薄膜样品的发光性能。结果表明:获得样品为六角纤锌矿结构的多晶薄膜材料沿[002]方向择优生长;样品表面均匀、致密,厚度约为550nm;在可见光波段具有高的透射率(>80%)。
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采用一种改进的液相成膜技术——连续离子层吸附与反应(SILAR)法,用锌氨络离子[Zn(NH3)4]2+溶液作为独立的前驱体溶液,以载玻片为衬底,在(125±5)℃的温度下沉积出致密、透明的ZnO薄膜。分别用冷场发射型扫描电镜(FESEM)和X射线衍射(XRD)分析了薄膜样品的表面形貌和结晶状态,用紫外-可见分光光度计(UV-Vis spectroscopy)研究了薄膜样品的发光性能。结果表明:获得样品为六角纤锌矿结构的多晶薄膜材料沿[002]方向择优生长;样品表面均匀、致密,厚度约为550nm;在可见光波段具有高的透射率(>80%)。
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利用电化学沉积方法在重离子径迹模板中制备出直径从45nm到200nm,长径比达700的金纳米线阵列,利用扫描电子显微镜(SEM)和X射线衍射(XRD)对所制备金纳米线的形貌及晶体结构进行分析,结果表明,在1.5V(无参比电极)沉积电压下所制备出的直径为200nm金纳米线沿[100]晶向具有较好择优取向.利用紫外-可见光谱(UV-Vis)对镶嵌在透明模板中平行排列的金纳米线阵列光学特性进行研究,发现金纳米线直径为45nm时,其紫外可见光谱在539nm处有强烈吸收峰,随着金纳米线直径增加,吸收峰红移,当金纳米线直径达到200nm时,其吸收峰峰位移至700nm.结合金纳米颗粒相关表面等离子体共振吸收效应对实验结果进行了讨论.
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采用蚀刻的聚碳酸酯(PC)离子径迹膜为模板,结合电化学沉积技术,制备出了直径为100~320 nm、长度从几μm到30μm的聚吡咯纳米线。利用场发射扫描电子显微镜(FESEM)、透射电子显微镜(TEM)对纳米线的形貌进行了表征。结果表明,所制备出的聚吡咯纳米线均呈圆柱形,且表面光滑、粗细一致。聚吡咯纳米线的紫外-可见(UV-Vis)光谱分析表明,随着聚吡咯纳米线直径增加,聚吡咯纳米线吸收峰展宽,且峰位向长波方向移动。
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用傅立叶变换红外光 (FTIR)谱仪和紫外 /可见光 (UV/VIS)谱仪研究了2 1GeVKr离子在聚碳酸酯 (PC)膜中产生的效应 .研究结果表明 ,在高能Kr离子辐照下 ,PC膜中发生了断键、断链和键的重组 ,炔基的出现是键的断裂和重组的结果 .这些效应与辐照剂量和电子能损有关 .辐照也使PC膜中发生了从氢化非晶态碳向非晶态碳的转变 ,在UV/VIS中 ,波长为 3 80 ,4 50和 50 0nm处的相对吸光度随能量沉积密度的增加近似按线性变化