ODMR study of the nature of iron-red photoluminescence in ZnS crystals

Basing upon the ODMR (optically detected magnetic resonance) measurements on the so-called iron-red (Fe-R) luminescence in ZnS it is shown that the emission is due to the radiative capture of either free or weakly bound electron by substitutional Fe³⁺ associated with an unknown defect residing in n.n. Zn position.     

ODMR study of recombination processes in ionic crystals and silicon carbide

The paper presents the results of optically detected magnetic resonance (ODMR) study of tunneling and photostimulated recombination processes in irradiated ionic crystals, observation of resonance effects using optically pumped F-centres, and investigation of spin-dependent recombination processes in silicon carbide doped with boron, aluminium, gallium and scandium.     

Defects in Nanodiamonds: Application of High-Frequency cw and Pulse EPR,ODMR

Different aspects of applications of electron paramagnetic resonance (EPR) based techniques including high frequency (HF) electron spin echo (ESE), electron-nuclear double resonance (ENDOR) and optically detected magnetic resonance (ODMR) approaches to study diamond nanostructures are examined.     

Saturation of the ODMR effect on singlet exciton induced emission in molecular crystals: Application to crystalline tetracene

We have studied the variation of the ODMR effect according to the intensity of a microwave field. We have highlighted a saturation effect of ODMR lines. This effect has been studied as part of the kinetic theory by developing the pilot equation while utilizing for the first time the formalism of a superoperator coupled with a time dependent sinusoidal perturbation. The agreement of the best fit between the experiment and the theory gives the mixing between singlet and quintuplet states, which seems to depend on the direction of the applied magnetic field.Received: 22 September 2003, Published online: 28 May 2004PACS: 71.35.-y Excitons and related phenomena - 32.30.Dx Magnetic resonance spectra - 76.70.Hb Optically detected magnetic resonance (ODMR)     

Subnanosecond spectrofluorimetry of new indolocarbazole derivatives in solutions and protein complexes and their dipole moments

The spectral and temporal characteristics of new 6,12-dimethoxyindolo[3,2-b]carbazole, 5,11-dimethyl-6,12-dimethoxyindolo[3,2-b]carbazole, and 5,11-dihexyl-6,12-di(hexyloxy)indolo[3,2-b]carbazole fluorescence probes in organic solvents and protein complexes are studied. The dipole moments of indolocarbazoles in 1,4-dioxane were measured by electrooptical absorption method. The measured dipole moments have values within the range of (3.1–3.6) × 10⁻³⁰ C m in the equilibrium ground state and increase to (4.8–5.6) × 10⁻³⁰ C m after excitation. The excited state lifetime of indolocarbazole derivatives increases with increasing polarity and viscosity of the environment. The binding of indolocarbazoles with trypsinogen and human serum albumin increases the fluorescence intensity, changes the intensity ratio of fluorescence bands, and increases the average excited state lifetime of indolocarbazoles. The analysis of the instantaneous fluorescence spectra and fluorescence decay parameters at different wavelengths revealed the existence of several types of probe binding sites in proteins. It is found that the fluorescence characteristics of indolocarbazole derivatives depend on the conformation rearrangements of trypsinogen due to its thermal denaturation.     

A computational study of model hydrogen-, halogen-, beryllium- and magnesium-bonded complexes of aziridine derivatives

ABSTRACT

A computational study of the complexes F^?/H₂O…Z-aziridine, Z-aziridine…BeH₂/MgH₂ and F^?/H₂O…Z-aziridine…BeH₂ /MgH₂ (Z = Cl, H, Li) was undertaken in order to investigate the non-covalent interactions operative in the dimers and to assess their interplay in the trimer complexes. The halogen- and hydrogen-bonds between the O and Z atoms in F^?/H₂O…Z-aziridine are enhanced in the trimers by the Be(Mg) bond and vice versa, but the lithium bond is hardly affected. In the trimers containing F^?, the H bond is more dominant than the Be(Mg) bond, whereas the Be(Mg) bond is more dominant in the halogen- and lithium-bonded analogues. On the other hand, the Be(Mg) bond makes the major contribution to the energetic stability of all of the trimers containing H₂O.     

Spectroscopic and Binding Properties of Berberine to DNA and Its Application to DNA Detection

Berberine(BER) binds to the double helical DNA with a high affinity There is only a much smaller hypochromism and no shifts in the absorption spectra when BER binds to calf thymus DNA(CT DNA) The fluorescence yields increase dramatically when BER binds to DNA, with no shifts in the emission maximum. These spectral changes are in contrast to the behavior observed with many fluorescent intercalates Groove binding rather than intercalation was suggested to be the cause of these spectral changes. Consistent with groove binding, for polyamide anion quenching studies showed that the magnitude of K_sv of the bound BER was higher than that of the free BER. The addition of salt to the solution releases the DNA-bound drug action from the groove and causes a decrease in the fluorescence yield. The results of all above studies proved the groove binding of BER to DNA. The large fluorescence enhancements observed when BER binds to DNA and the poor fluorescence yield of BER in the absence of DNA can be used for sensitive detection of DNA The linear concentration range was 0–20μg/ml The limit of detection for CT DNA was 12 ng/ml     

四种D—氨基葡萄糖甘氨酸混配金属配合物与DNA作用的SERS光…

研究了四种Ｄ－氨基葡萄糖甘氨酸混配合金属配合物的表面增强喇曼光谱（ＳＥＲＳ），发现它们在角胶上的吸附方式基本相同，因而ＳＥＲＳ光谱也基本相似，并用ＳＥＲＳ光谱研究了它们与ＤＮＡ的相互作用，发现这四种化合物与ＤＮＡ的作用能力有很大不同，Ｃｏ（Ⅲ）ＧｌｕＧ是值得进一步研究的可能抗癌药物。     

An extension of Noether's theorem to transformations involving position-dependent parameters and their derivatives

Guided by the example of gauge transformations associated with classical Yang-Mills fields, a very general class of transformations is considered. The explicit representation of these transformations involves not only the independent and the dependent field variables, but also a set of position-dependent parameters together with their first derivatives. The stipulation that an action integral associated with the field variables be invariant under such transformations gives rise to a set of three conditions involving the Lagrangian and its derivatives, together with derivatives of the functions that define the transformations. These invariance identities constitute an extension of the classical theorem of Noether to general transformations of this kind. An application to the case of gauge fields demonstrates the existence of two distinct types of conservation laws for such fields.     

μSR studies of fullerenes and their derivatives

The dynamic properties of pristine C₆₀ and C₇₀ are reviewed, emphasizing the results of the ZF‐ and ALC‐μ⁺SR techniques. In C₆₀, the \mboxfcc\rightarrow\mboxsc transition is accompanied by a change in the dynamics from isotropic reorientational to quasi‐random jump motion between nearly‐degenerate orientations. C₇₀ is frozen on a timescale of 30 ns up to 170 K. At higher temperatures, the motion is found to be complex, consisting of a uniaxial rotation part together with a nutational or jumping motion of the unique axis. Anisotropy on the 30 ns timescale persists to 370 K, well into the fcc phase. The ZF‐μ⁺SR technique has been also employed to study the magnetic properties of fullerides. In the organic salt (TDAE)C₆₀, spontaneous magnetic order is directly observed below a Curie temperature of 16.1 K, higher than any other organic material. In the quasi‐one‐dimensional conductor CsC₆₀, static magnetic order of a random nature is observed to develop in the vicinity of the metal–insulator transition at 30 K with no direct evidence of long range order present. This revised version was published online in August 2006 with corrections to the Cover Date.     

α-异噁唑偶氮基-β-二酮类衍生物及其互变异构体的光谱

研究了5种新型的具有不同结构的aα-异噁唑偶氮基-β-二酮类衍生物的红外光谱和紫外光谱，讨论了它们的酮式-烯醇式以及偶氮式．腙式之间的互变异构化现象。结果表明，所有化合物无论以固体形式或在溶液中均以腙式二酮体和偶氮式烯醇体的混合形式存在。各化合物的紫外吸收谱均呈双峰状，峰值分别处于246～262nm和326～339nm之间，其中，高波长吸收峰的强度明显高于低波长吸收峰强度，说明了各化合物中偶氮式烯醇体形式均多于腙式二酮体形式，其原因是由于各化合物中偶氮式烯醇体的异构体较多，且易以分子内氢键形式形成六元环，有利于结构稳定。     

X-ray photoelectron spectroscopy of nitroanilines and their derivatives

N 1s core-electron spectra have been studied for nitroanilines and related compounds. The spectral data are qualitatively interpreted by means of the molecules-in-molecule method, which describes the interaction between the aromatic amine part (donor moiety) and the nitro group (acceptor moiety) in terms of a composite system consisting of a donor and an acceptor. It was found that the nitro-N 1s spectra and the separation between the nitro-N 1s and the amino-N 1s ionization energies depend upon the magnitude of the intramolecular charge-transfer interaction in the ground state. A similarity between the relaxation effect in the nitro-N 1s or nitro-O 1s core-hole ion and a nitration reaction of the donor moiety is demonstrated.     

第五讲生物医学信息处理--DNA微阵列数据在医学中的应用

飞速发展的生物信息技术为现代医学提供了更为有效的工具．特别是随着人类基因组计划的基本完成和逐步细化，人们已经试图从基因水平上来认识生命现象，特别是一些重要疾病的机理．由于生物特性一般都涉及到多个基因的共同表达，这便出现了同时衡量成千上万个基因的表现水平的所谓DNA微阵列技术与数据．DNA微阵列数据也被称为大规模基因表达谱．根据这些微阵列数据，人们不仅能够对一些疾病进行分析，并且还能够发现一些新的生物特性与规律．另外，利用微阵列数据能够选取出疾病的相关基因并进行疾病的分类与诊断．这项研究无疑将推动医学的发展．最近，人们还进一步通过基因表达水平值来发现基因之间的调控方式，这将为疾病病理的研究与治疗提供更科学的依据．     

第五讲 生物医学信息处理——DNA微阵列数据在医学中的应用

飞速发展的生物信息技术为现代医学提供了更为有效的工具.特别是随着人类基因组计划的基本完成和逐步细化,人们已经试图从基因水平上来认识生命现象,特别是一些重要疾病的机理.由于生物特性一般都涉及到多个基因的共同表达,这便出现了同时衡量成千上万个基因的表现水平的所谓DNA微阵列技术与数据.DNA微阵列数据也被称为大规模基因表达谱.根据这些微阵列数据,人们不仅能够对一些疾病进行分析,并且还能够发现一些新的生物特性与规律.另外,利用微阵列数据能够选取出疾病的相关基因并进行疾病的分类与诊断.这项研究无疑将推动医学的发展.最近,人们还进一步通过基因表达水平值来发现基因之间的调控方式,这将为疾病病理的研究与治疗提供更科学的依据.     

Atomic-force microscopy studies of the complexes of DNA and single-wall carbon nanotubes

The interaction of DNA samples extracted from tobacco leaves of two types with carbon nanotubes (CNTs) was studied. Atomic-force microscopy images of DNA-CNT complex films were obtained. The possibility of forming ordered self-assembling structures in a DNA-CNT film was shown.     

Study of transient luminescence of three kinds of Ru complexes bound to DNA

The transient luminescence of three kinds of ruthenium complexes [Ru(bpy)₂(7-CH₃-dppz)]²⁺, [Ru(bpy)₂(7-F-dppz)]²⁺ and [Ru(phen)₂(7-F-dppz)]²⁺ bound to calf thymus DNA (ctDNA) has been studied by using the time-resolved spectroscopy. The results show that the luminescence is due to the radiative decay from the charge-transfer states to the ground state. By the interaction with DNA, the radiativeless rate of the photoexcited Ru complex molecules decreases, which results in the increase of luminescence lifetime and efficiency. The structure of the Ru complex has an important impact on the interaction with DNA. The [Ru(bpy)₂(7-CH₃-dppz)]²⁺ shows the longest luminescence lifetime (about 382 ns), while the [Ru(bpy)₂(7-F-dppz)]²⁺ shows the shortest lifetime (about 65 ns). The possible origin of the luminescence dynamics is discussed. Supported by the National Natural Science Foundation of China (Grant Nos. 60478013 and 20571089), the Key Program of Natural Science Foundation of Guangdong Province of China (Grant No. 05101819), the Doctoral Program Foundation of Institutions of Higher Education of China (Grant No. 20040558031) and the Scientific Research Foundation of Maoming College (Grant No. 203346)     

Relative facility of the desulfurization of amino acids and their carboxylic derivatives

As an excellent alternative to native chemical ligations, the ligation–desulfurization strategy enables the ligations on the other N‐terminal peptides (in addition to Cys) and is highly promising in peptide synthesis. In the present study, the relative facility of the desulfurization on the pre‐sulfurized amino acids and their carboxylate derivatives has been examined with the aid of density functional theory calculations. It is found that the C–SH bond strengths of the sulfurized amino acids directly relate to the stability of the formed radical. By contrast, the carboxylation of the sulfurized amino acids greatly stabilizes the carbonyl radical center, and both the steric and electronic effects are important factors in determining the C–SH bond strength of the carboxylate precursors. Copyright © 2015 John Wiley & Sons, Ltd.     

Fluorescence of crown-containing styryl dyes and their metal complexes

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 62, No. 3, pp. 69–72, May–June, 1995.