Spectral moments of polymer graphs

Summary It is shown that for anyk, thekth spectral moment of a polymer graph composed ofn monomer units is an exact linear function of the parametern. This linear relation holds for all values ofn, greater than a critical value ₀=₀(k).on leave from Faculty of Science, University of Kragujevac     

Analysis of the relationship among the graphs isomorphic to multilayered cyclic fence graphs (MLCFG)

Multilayered cyclic fence graphs (MLCFG, E(m,n), F(m,n), D(m,n), G(m,n), X(m,n)) are proposed to be defined, all of which are composed of m 2n-membered cycles with periodic bridging. They are also cubic and bipartite. Hamiltonian wheel graph, H (n,[j(k)]), and parallelogram-shaped polyhex graph are also defined. All the members of MLCFGs are found to be isomorphic to the so-called "torus benzenoid graphs", while some members of MLCFGs are found to be related to the Hamilton wheel graphs. Through the construction of Hamilton wheel graph and the matrix representation by Kirby, a number of isomorphic relations among MLCFGs, Hamilton wheel graphs, and polyhex graphs were obtained. These relations among the MLCFG members were found also by the help of the characteristic quantities of MLCFGs.     

Spectral characteristics of polyaniline nanostructures synthesized by using cyclic voltammetry at different scan rates

The polyaniline nanofibers with different sizes were synthesized by using cyclic voltammetry at different potential scan rates, in the presence of ferrocenesulfonic acid. The potential scan rate controlled the formation and growth of polyaniline nuclei, which plays a key role in controlling nanofiber sizes. The average diameters of nanofibers decreased from about 130 nm to about 80 nm as the potential scan rate increased from 6 to 60 mV s (-1). We first observed an ordered change in the following spectra with the nanofiber sizes of polyaniline. The spectra of the X-ray diffraction indicated that the partially crystalline form existed in the polyaniline nanofibers and that the crystallinity of polyaniline increased with decreasing diameter of polyaniline nanofibers. The ESR spectra revealed the fact that the decrease in the intensity of the ESR signal was accompanied by the increase in the value of the peak-to-peak line width Delta H pp as the diameter of polyaniline nanofibers decreased. The (1)H NMR spectra showed that a peak in a triplet caused by the +/- NH free radical was split into two peaks with different intensities and that their relative intensity also changed with the diameter of the polyaniline nanofibers.     

Spectral analysis of acetylcholine halides by density functional theory calculations

The optimized molecular structures, vibrational frequencies and ¹H and ¹³C NMR chemical shifts of acetylcholine halides (F, Cl, and Br) have been investigated using density functional theory (B3LYP) method with 6-311G(d) basis set. The comparison of their experimental and calculated IR, R and NMR spectra of the compounds has indicated that the spectra of three optimized minimum energy conformers can simultaneously exist in one experimental spectrum. Thus, it was concluded that the compounds simultaneously exist in three conformations in the ground state. The calculated optimized geometric parameters (bond lengths and bond angles), vibrational frequencies and NMR chemical shifts for the minimum energy conformers were seen to be in a good agreement with the corresponding experimental data. All the assignments of the theoretical frequencies were performed by potential energy distributions using VEDA 4 program.     

人发的光谱分析进展

评述了用分光光度、荧光（原子荧光）、原子吸收、原子发射光谱方法进行人发中我种元素测定的分析（包括发样采集、洗涤、消化），引用文献９６篇。     

Spectral analysis of the Green's function

The energy eigenvalue spectrum for a conservative dynamical system is contained implicitly in its Green's function. It becomes explicit in the Fourier transform of either the Green's function or its trace. The trace exists only when the spectrum is entirely discrete. Applications are made to the free particle, the linear harmonic oscillator, and the hydrogen atom. In the latter two cases determination of the Green's function can be considerably simplified by similarity transformations on the Hamiltonian operator.     

Walk counts, labyrinthicity, and complexity of acyclic and cyclic graphs and molecules

It is demonstrated how the complexity of a (molecular) graph can be quantified in terms of the walk counts, extremely easily obtained graph invariants that depend on size, branching, cyclicity, and edge and vertex weights (unsaturation, heteroatoms). The influence of symmetry is easily accounted for. The term labyrinthicity is proposed for what is measured by walk counts alone, neglecting symmetry. The total walk count and recently advanced measures of labyrinthicity or complexity are compared with respect to the ordering of structures and to the computational effort required to obtain numerical values.     

Conformational analysis of six-membered cyclic carbonates

The conformational isomerization of 2-oxo-1,3-dioxane and its methyl analogs was investigated by means of ab initio RHF//6-31G(d,p) and MP2//6-31G(d,p) quantum-chemical methods. It is shown that in comparison with 1,3-dioxanes the potential energy surface of the mentioned compounds has a fewer number of stationary points and includes two minima corresponding to conformers of sofa or distorted sofa configuration and one maximum corresponding to 2,5-twist form. The value of potential barrier of interconversion of cyclic carbonates is significantly lower than that of the analogously substituted 1,3-dioxanes.     

Configurational analysis of diastereomeric open-chain and cyclic nitro-substituted diols by NMR spectroscopy

Nitro-substituted 1,3-dioxanes and pyrans with potential biological activity were synthesized. The relative configurations of the threo and erythro isomers of 2-nitro-1-phenylpropane-1,3-diol (the starting materials) and of 5-nitro-2,4-diphenyl-1,3-dioxane, the products formed with benzaldehyde, were determined by ¹H and ¹³C NMR spectroscopy. Cinnamaldehyde and nitroethanol give a homologue of nitrophenylpropanediol, which exists as a mixture of two diastereomeric cyclic hemiacetals. After dissolving in CDCl₃, the ratio of these components changes from approximately 10:1 to 3:2 in a few days. The ethyl acetal of the hemiacetal is stereohomogeneous, and the ethoxy group is axial to the pyran ring owing to the anomeric effect. This configuration was proved by two-dimensional NMR measurement, permitting separate observation of the originally overlapping multiplets and direct reading of the H,H coupling constants.     

Macromolecular polyradicals with cyclic triphosphazene as a core. Spectral and electrochemical properties

Stable cyclotriphosphazenes 5 and 6, with three and four carbon radical centers, have been prepared by condensation of (4-hydroxy-2,6-dichlorophenyl)bis(2,4,6-trichlorophenyl)methyl radical (4) with tetrachloro-2,2'-dioxybiphenylcyclotriphosphazene (7). EPR studies of both polyradicals in fluid solution suggest an electronic communication through the PN multiple bonds of the cycle. EPR spectral results in frozen solutions and magnetic susceptibility measurements in the solid are consistent with very weak electron-electron dipolar interactions. Reductive cyclic voltammetry shows a single three-electron redox couple for triradical 5 and a single four-electron redox couple for tetraradical 6. Both polyradicals 5 and 6 have been chemically oxidized to a stable trication 5(3+) and a tetracation 6(4+), respectively, by electron-transfer reactions.     

Dynamic electro-chemo-mechanical analysis during cyclic voltammetry

We report and validate a method for measuring the strain-response, ?, of the electrode potential of electrically conductive solids in a fluid electrolyte. Simultaneously with cyclic voltammetry, the electrode is subjected to cyclic elastic strain at frequencies of up to 100 Hz. We explore three independent strategies for separating the cyclic variation of potential or current from the voltammogram proper, and find that the results of all three are in quantitative agreement. By means of an example we explore dominantly capacitive processes at a gold electrode in H(2)SO(4) and HClO(4). The response parameter ? is not sensitive to the nature of the electrolyte. Yet, its value varies by more than a factor of two in the potential interval investigated. The potential of largest magnitude of ? agrees closely with the potential of zero charge.     

美沙拉秦的波谱学数据与结构表征

对美沙拉秦的红外光谱（IR）、紫外光谱（UV）、质谱（MS）、碳谱（DEPT-135）、碳氢相关谱（HMQC）予以解析和报道.对所有1H NMR和13C NMR谱的信号进行了归属;同时讨论了质谱的主要碎片离子可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式.     

Spectral analysis of a fluid under thermal constraint

Abstract

A spectral analysis is presented to investigate the onset of the convective instability in a fluid subject to a linear temperature gradient. The hydrodynamic theory is developed for the case of a binary system, where the concentration of one of the components is small. Therefore the present results will be applicable to the case of a Brownian system. We consider exclusively those modes which correspond to the central components of the spectral distribution, i.e., the diffusion mode and the thermal diffusivity mode. One finds that those modes are effected by the presence of the external temperature gradient in such a way that the spectrum of the scattered light should exhibit an important narrowing of the thermal diffusivity peak and a slight narrowing of the diffusion peak when approaching the convective instability critical point. Only the thermal diffusivity mode is affected in the limit of a pure fluid     

Evaluation of homogeneity of selected reference materials for selenium by cyclic neutron activation analysis

The homogeneity of four reference materials was evaluated for Se by cyclic instrumental neutron activation analysis (CINAA). The relative standard deviation for Se measurements at ppb levels by CINAA was <12% for NIST Wheat Flour (SRM 1567) in 5–10 mg samples, while it was <11% for Chinese Hair (HH–CH-1), <13% for IAEA Animal Muscle (H-4) and 25% for IAEA Animal Blood (A-13) in 50 mg samples. The highest relative subsampling uncertainties were observed in the mass range of samples 50 mg for Chinese Hair, 100 mg for Wheat Flour and Animal Muscle and 300 mg for Animal Blood. The results of a one-way analysis of variance indicate that all reference materials above these mass ranges are adequately homogeneous with respect to Se distribution. Our data suggest that these materials, except Animal Blood, can be used as reference standards for Se in Quality assurance programs well below the sample masses re commended by the issuing agencies.     

Enumeration of digraphs with a given automorphism group

Four methods are described for enumerating digraphs with a given automorphism group: (1) a generating-function method based on subduced cycle indices, (2) a generating-function method based on partial cycle indices, (3) a method based on the elementary superposition theorem, and (4) a method based on the partial superposition theorem. All of these methods are based on the concept of unit subduced cycle indices and construct a set of versatile tools for combinatorial enumeration. They are applied to the enumeration of five-vertex digraphs with a given automorphism group. The table of marks and its inverse for the symmetric group of degree 5 are recalled. The table of USCIs of this roup is obtained.Dedicated to Professor Frank Harary.     

Microbial Degradation,Spectral analysis and Toxicological Assessment of Malachite Green Dye by Streptomyces exfoliatus

Malachite green (MG) dye is a common environmental pollutant that threatens human health and the integrity of the Earth’s ecosystem. The aim of this study was to investigate the potential biodegradation of MG dye by actinomycetes species isolated from planted soil near an industrial water effluent in Cairo, Egypt. The Streptomyces isolate St 45 was selected according to its high efficiency for laccase production. It was identified as S. exfoliatus based on phenotype and 16S rRNA molecular analysis and was deposited in the NCBI GenBank with the gene accession number {"type":"entrez-nucleotide","attrs":{"text":"OL720220","term_id":"2159919206","term_text":"OL720220"}}OL720220. Its growth kinetics were studied during an incubation time of 144 h, during which the growth rate was 0.4232 (µ/h), the duplication time (td) was 1.64 d, and multiplication rate (MR) was 0.61 h, with an MG decolorization value of 96% after 120 h of incubation at 25 °C. Eleven physical and nutritional factors (mannitol, frying oil waste, MgSO₄, NH₄NO₃, NH₄Cl, dye concentration, pH, agitation, temperature, inoculum size, and incubation time) were screened for significance in the biodegradation of MG by S. exfoliatus using PBD. Out of the eleven factors screened in PBD, five (dye concentration, frying oil waste, MgSO₄, inoculum size, and pH) were shown to be significant in the decolorization process. Central composite design (CCD) was applied to optimize the biodegradation of MG. Maximum decolorization was attained using the following optimal conditions: food oil waste, 7.5 mL/L; MgSO₄, 0.35 g/L; dye concentration, 0.04 g/L; pH, 4.0; and inoculum size, 12.5%. The products from the degradation of MG by S. exfoliatus were characterized using high-performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The results revealed the presence of several compounds, including leuco-malachite green, di(tert-butyl)(2-phenylethoxy) silane, 1,3-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, 1,4-benzenedicarboxylic acid, bis(2-ethylhexyl) ester, 1,2-benzenedicarboxylic acid, di-n-octyl phthalate, and 1,2-benzenedicarboxylic acid, dioctyl ester. Moreover, the phytotoxicity, microbial toxicity, and cytotoxicity tests confirmed that the byproducts of MG degradation were not toxic to plants, microbes, or human cells. The results of this work implicate S. exfoliatus as a novel strain for MG biodegradation in different environments.