Ultraviolet Absorption Peak Research Articles

Some Effects of Hydrallazine on Blood Iron and an Iron-Containing Enzyme System

Abstract A hydrallazine-iron chelation complex has been prepared and shown to have a m.p. of 210°, and no ultra-violet absorption peak at 265 mμ. It has no hypotensive properties and does not antagonise the pressor response to adrenaline in the rat. At high dose levels hydrallazine inhibits catalase activity in vitro but not in vivo. The iron catalysed oxidation of cysteine to cystine is also inhibited by hydrallazine. Hydrallazine at high dose levels has been shown to cause haemolysis in vivo and in vitro. A consistent effect upon iron-excretion could not be shown.

Hemibonding between Hydroxyl Radical and Water

The ultraviolet absorption peak commonly used to identify OH radical in liquid water is mainly due to a charge-transfer-from-solvent transition that is prominent when OH is hemibonded, rather than more stable hydrogen bonded, to H(2)O. This work computationally characterizes the hemibonding interaction and the extent of the geometrical region over which it is significant. Hemibonding is found to be associated with an enlarged energy separation between the two lowest-lying electronic states, which are otherwise always quite close to one another. The lower state, wherein the hemibonding occurs, retains an attractive interaction energy between OH and H(2)O that can be as much as one-half as strong as the optimum hydrogen-bonding interaction, while the enlarged separation between the states is mainly due to the upper state becoming repulsive over most of the hemibonding region. Hemibonding also leads to a considerable drop in the energy and a considerable increase in the oscillator strength of the characteristic charge-transfer transition. The region of significant hemibonding is found to lie within a moderate range of O-O azimuthal angles and over quite wide ranges of O-O separation distances and hydroxyl OH tilt angles. In particular, significant hemibonding interactions can extend down to surprisingly short O-O distances, where the oscillator strength for the charge-transfer-from-solvent transition becomes very large.

A Novel Method for the Determination of Total Hydrocarbon in the Hydrocarbon Mixture-Contaminated Soil

A simple, reliable and rapid analysis method, for the determination of total hydrocarbon content in a hydrocarbon mixture-contaminated soil that derived from a drum washing factory, was described and validated for the remediation of the contaminated site. This method was based on an assumption that the possibly extracted total hydrocarbon by organic solvent in the hydrocarbon mixture-contaminated soil had a ultraviolet absorption peak and could be used as hydrocarbon mixture standard sample (MSS), by which total hydrocarbon content in the contaminated soil could be measured using ultraviolet spectrophotometry instead of traditional analysis methods (GC, HPLC, GC-MS and HPLC-MS). The results shown that after the available MSS was dissolved in dichloromethane, it stably exhibited ultraviolet absorption peak at 230 nm and the calibration curve for absorbance versus concentrations indicated a high correlation (r=0.9999, p<0.001). The recoveries of this method were in the range of 81.43-104.49% with total hydrocarbon content ranging from 150 to 9000 mg kg-1 when extracted with pure dichloromethane; and the soil organic matter (SOM) interference with this method was negligible due to the percentage of transported concentration of SOM in total hydrocarbon content of contaminated soil was less than 1%. In general, the proposed method had the advantages of convenience, simplicity and good repeatability, and could be used to rapidly determine the total hydrocarbon content in hydrocarbon mixture-contaminated soils in this study. However, heavy metals exhibited interference in this method and it was necessary to analyze the existence of heavy metals prior to the adoption of this method.

Comparative Studies on Degradation of Methyl Orange by Nanostructured Zinc and Zinc Oxide Films

Nanostructured zinc and zinc oxide films were prepared by magnetron sputtering processes and succeeded air annealing treatments. Comparison of reductive degradation rate of methyl orange (MO) by zinc films and photocatalytic degradation rate of MO by zinc oxide films was carried out. Both reductive degradation and photocatalytic degradation process of MO by zinc and zinc oxide films can be described by first order kinetic model. It was found that although MO liquid was most quickly decolorized by metallic zinc films, the mineralization of MO was not thorough. Observation of extra ultraviolet absorption peaks indicated the formation of aromatic intermediates. On the other hand, although the photocatalytic degradation rate of MO liquid by ZnO films was only as about 1/4 large as the reductive degradation rate by zinc films, no signs of aromatic intermediates were found. Moreover, it was found that partially oxidized zinc oxide film showed higher photocatalytic efficiency than the totally oxidized ZnO films. Synergy effect between zinc and zinc oxide phase in the partially oxidized films was considered to be responsible for the higher photocatalytic efficiency.

Hydrothermal synthesis of CeF3 nanocrystals and characterization

CeF3 nanocrystals with plate-like and perforated morphologies were successfully synthesized via a facile hydrothermal route. The nanocrystals of CeF3@silica can dispersed in aqueous solution were also prepared. The effects of fluoride sources on the morphology and microstructure of the nanocrystals were investigated by means of transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and powder X-ray diffraction (XRD). Results indicate that the morphology of the rare earth compound nanocrystals can be well tuned by selecting proper fluoride sources. The ultraviolet (UV) absorption peak of the CeF3 nanocrystals is slightly blue shifted along with the decrease of size. And the photoluminescence (PL) intensity of the CeF3 nanocrystals is closely related to size and microstructure as well.

The Optical Properties of Single-Walled Carbon Nanotubes in the Ultraviolet Region

The absorption properties of single-walled nanotubes in the ultraviolet (UV) region have been studied using a generalized tight-binding approximation. Calculations indicate that the absorption spectrum in the UV region strongly depends not only on nanotube diameter but also on chiral index. We found a substantial diameter dependence of the UV absorption peaks of the nanotubes with chiral indices of (even, even) and (odd, even). The nanotubes with chiral indices of (even, odd) and (odd, odd) exhibit weak diameter dependence. These spectral features are characteristic of inter-band transitions near the M point of the hexagonal Brillouin zone of graphene.

Antagonism and Action Mechanism of Antifungal Metabolites fromStreptomyces rimosusMY02

The genus of Streptomyces, a saprophytic Gram-positive bacterium, has properties, which make them useful as pharmaceutical and biocontrol agents. A streptomyces strain MY02 from soil samples showed significant antagonism against 14 plant pathogenic fungi including Fusarium oxysporum f. sp. cucumarinum. Antifungal metabolite(s) SN06 from the culture of the strain MY02 were extracted with n-butanol and purified by silica gel column chromatography. The minimum concentration of SN06 inhibiting any visible fungal growth of F. oxysporum f. sp. cucumarinum is 12.5 μg/ml by twofold serial dilutions method. The mycelia of F. oxysporum f. sp. cucumarinum treated with SN06 were observed under the normal optics microscope. The results showed that some cells of hyphae began to dilate and formed some strings of beads. The cytoplasm oozed out of the cells with the culture time and so most of the cells became empty. The hyphae broke into many segments and then collapsed after 48 h. After inoculated in potato dextrose medium for 48 h, the filtrate of mycelia treated with 1% NaCl containing 12.5 μg/ml SN06 was scanned using ultraviolet spectrophotometer and absorption peak at 260 nm showed that the mycelia cell membrane of F. oxysporum f. sp. cucumarinum was broken and that nucleic acid oozed out of the cell.

Synthesis of CdTe colloidal quantum dots (QDs) in water

The comparison of growth processes and fluorescent properties of CdTe semiconductor quantum dots (QDs) that are synthesized in water with different modifiers are discussed in this paper. The samples are characterized through ultraviolet-visible spectra (UV-Vis), photoluminescence spectra (PL) and zeta potential. The results show that when the reaction time is prolonged for the same modifier, the ultraviolet absorption peak and fluorescent emission peak present obvious red shifts and the diameters of the QDs continuously increase. With the same reaction time but different modifiers, QDs with different diameters can be gained. The average full width at half maximum of the photoluminescence spectra is about 50 nm which shows that the monodispersity is quite good. Under the best reaction conditions, the highest quantum yield (QY) can be attained by using thioglycollic acid (TGA) as modifier when the reaction time is 240 min. The zeta potential is influenced by the modifier and pH.

A greener synthetic route to monodisperse CdSe quantum dots with zinc-blende structure

A much cheaper and greener route to monodisperse CdSe quantum dots (QDs) with zinc-blende structure has been developed. The N, N-dimethyl-oleoyl amide was chosen as the solvent, eliminating the needs of air-sensitive and toxic trioctylphosphine (TOP) or tributylphosphine (TBP), and cadmium oxide and elemental selenium as sources. The as-prepared CdSe QDs show an apparent blue-shift in the ultraviolet and visible (UV–vis) absorption peaks. The emission peak of the QDs can be tuned by changing synthesis time only.

Dual surface plasmon resonances in Zn nanoparticles inSiO2: an experimental study based on optical absorption and thermal stability

Metallic zinc nanoparticles (NPs) of 5–15 nm in diameter, formed in silica glass(SiO2) by Zn ion implantation of 60 keV, showed a strong ultraviolet absorption peak at around4.8 eV, which has been assigned as the surface plasmon resonance (SPR) of ZnNPs, and another small peak at 1.2 eV, which has never been reported before.To identify the origin of the 1.2 eV peak, the correlations of thermal stabilitybetween the two peaks and Zn NPs were evaluated under annealing both in avacuum (pure thermal stability) and in oxygen gas (thermal oxidation stability).The well-correlated stability between the 1.2 eV peak, the 4.8 eV peak and ZnNPs indicates that the 1.2 eV peak is not ascribed to radiation-induced defectsbut to the Zn NPs. The 1.2 eV peak can be ascribed to an SPR of Zn NPs inSiO2, because the peak satisfies the criterion of the SPR of metallic NPs.Since the 4.8 eV peak is also expected to satisfy the criterion, Zn NPs inSiO2 have two SPRs at 1.2 and 4.8 eV.

Synthesis and characterization of carboxymethyl chitosan containing functional ultraviolet absorber substituent

AbstractA series of carboxymethyl chitosan (CMC) with 2.4‐dihydoxybenzophenone (UV‐0) substituent were synthesized by the Mannich reaction of CMC hydrochloride and UV‐0 in the solvent of methanol and water. The different molar degree of substitution (MS) was achieved by changing the UV‐0 content. The effects of MS on ultraviolet absorbability, crystallinity, moisture‐absorption and ‐retention property, and photostability were investigated respectively. The obtained products were characterized by means of Fourier transform infrared spectra (FTIR), proton nuclear magnetic resonance spectroscopy (1H NMR), X‐ray diffraction, and UV spectrophotometer. It was found that the grafted products were water‐soluble, and the increased MS values could enhance the moisture‐retention property and photostability, while decreased the crystallinity and moisture‐absorption property. The ultraviolet absorption peaks became stronger by introducing UV‐0 into the CMC backbones. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

Synthesis of Hydroxystilbene Derivatives and their Antioxidant Activity by DPPH Method

Five hydroxystilbene derivatives were synthesized and their structures were determined using high-resolution mass spectrometry, 1H NMR, and IR. In this study, the antioxidant activities of eight hydroxystilbenes(five synthesized hydroxystilbene derivatives and three other compounds) were evaluated with the free radical scavenging model 1, 1-diphenyl-2-picrylhydrazyl. It was observed that there exists a very significant linear relationship between the reciprocal of the EC 50, value of each of the compounds and the maximum wavelength of the ultraviolet absorption peaks. It is believed that this result will be helpful for the further synthesis of such antioxidants.

Using the Photolysis of Chemically Modified Gel Films Preparing ITO Fine Patterned Thin Films

A novel technique for the fabrication of tin-doped indium oxide (ITO) fine patterning in sol-gel technology is presented in this paper. The fabricated ITO fine patterning could be obtained through a process which combines film fabrication with film etching. ITO films have good comprehensive property of visible transmittance and electrical conductivity, consequently they have been extensively used as coating electrodes. Indium nitrate (In(NO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> .4.5H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 </sub> O) and stannic chloride ( SnCl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> .5H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O) were used as starting materials which were modified with benzytone (BzAcH). The chelate complexes containing indium ions were produced during the process which of forming photosensitive ITO/BzAcH gel films through sol-gel technique. It was found that the gel films are sensitive to both the ultraviolet (UV) light irradiation and their solubility on solvents as well. For example, ethanol was reduced remarkably while the UV absorption peak disappeared with the dissociation of the chelate complexes correspondingly by means of UV-vis and IR spectrophotometers. Utilizing these characteristics, a fine pattern was obtained by irradiation of UV light on the ITO/BzAcH gel films through a pattern mask. of the fine patterned ITO films were heat treated at 500degC for 15 min, the optical, electrical properties and the surface element components were examined by X-ray photoelectron spectroscopy (XPS) spectra in this work

Effect of Sb2O3-doped on optical absorption of ZnO thin film

Sb2O3 doped ZnO thin film was prepared by RF magnetron sputtering technique. The influence of Sb2O3 on the structure and the optical absorption of ZnO thin film was studied by XPS, XRD apparatuses and UV-Vis spectrophotometer. The results show that doped Sb2O3 has affected atomic and electronic structures, growth modes of crystal grains and optical absorption of ZnO. The element Sb exists in many forms in the film including transpositional atoms and compounds such as Sb2O3, Zn7Sb2O14 etc. ZnO crystal grains grow in mixing directions. The lattice relaxation and the content of second phases increase when more Sb is doped. The UVA absorption of doped ZnO thin film increases obviously. The ultraviolet absorption peak narrows, absorption intensity increases, the absorption margin becomes steep and moves to shorter wavelength of about 5 nm, and the visible absorption increases in some sort.

A New Route to Zinc-Blende CdSe Nanocrystals: Mechanism and Synthesis

We report the possible mechanism of forming of CdSe nanocrystals in the high boiling point solvents with long alkane chains and a novel Non-TOP-Based route to zinc-blende CdSe nanocrystals. A new mechanism shows that there exits a redox reaction in the long alkane chain solvents: Se is reduced to H2Se gas; at the same time, the long alkane chains are oxidated to alkene chains; then, the Cd complex reacts with H2Se to form CdSe nanocrystals. Possible chemical reaction equations involved in the process of forming the CdSe nanocrystals have been discussed. The alkene chain and H2Se were detected respectively by a series of experiments to support the new mechanism. Under the guidance of this mechanism, we have developed a much cheaper and greener Non-TOP-Based route for the synthesis of a size series of high-quality zinc-blende (cubic) CdSe nanocrystals. Low-cost, green, and environmentally friendlier reagents are used, without use of expensive solvents such as trioctylphosphine (TOP) or tributylphosphine (TBP). The new route enables us to achieve high-quality CdSe nanocrystals with sharp ultraviolet and visible (UV-vis) absorption peaks, controllable size (2.0-5.0 nm), bright photoluminescence (PL), narrow PL full width of half-maximum (fwhm) (29-48 nm), and high PL quantum yield (up to 60%) without any size sorting.

Calculations of the Absorption Spectrum of Chromone

We have performed a theoretical investigation of the optical properties of the molecule chromone, using multireference perturbation theory (CASPT2) and time-dependent density functional theory (DFT) methods. The structure of the molecule was optimized at the DFT level and at the level of complete active space self-consistent field (CASSCF). In addition to vertical excitation energies, we have computed the lowest adiabatic 1A‘ transition energy, as well as transition probabilities for all singlet transitions to low-lying states. Using this data, we can assign the four observed ultraviolet absorption peaks of chromone. Finally, we address the question of the aromaticity of the heterocyclic ring in chromone, an issue which has recently received some attention.

Theoretical studies of the electronic and optical properties of permethyl-oligosilanes

A systematic study was made on the optical absorption spectra of permethyl oligosilanes, CH3[CH3–Si–CH3]NCH3, as a function of their backbone chain length from N=2 to 16 by using first principles [density functional with local density approximation (LDA)] electronic structure calculations. The general features of the calculated spectra agree with those of experimental measurements. Analysis of the nature of optical transition revealed the existence of two qualitative crossovers at chain lengths of N=2 and around N=10 and 12. The first one is associated with the molecular orbitals giving rise to the first ultraviolet absorption peak, while the second one is associated with the crossover from ‘‘molecular’’ to ‘‘polymeric’’ as the oligomers become larger. The broadening of the first absorption peaks is estimated by the vibration modes and electronic relaxation energies in the oligomers. Comparison with calculated results by a model Hamiltonian based on the Sandorfy C model is made and the relative merit of semiempirical and LDA calculations is discussed.

Purification of endogenous inhibitors of [3H]flunitrazepam binding from bovine brain

Endogenous substances which inhibited the binding of [3H]flunitrazepam ([3H]FNZ) to bovine synaptosomal membranes have been purified from the hot acetic acid extracts of the bovine brain. Three peaks of inhibitory activity were obtained by Sephadex G-10 gel chromatography. Two of the peaks (Peak 2, and Peak 3) which had lower molecular weights than that of peak 1 were identified as inosine and hypoxanthine by TLC methods. Another peak (Peak 1) was further purified to homogeneity using both cation and anion ion-exchange chromatography and the following two-step reversed-phase HPLC. The purified substance inhibited the [3H]FNZ binding dose-dependently and competitively but did not have an effect on the binding of the peripheral-type BZ ligand [3H]Ro 5-4864. It was also shown that the substance was heat-stable and resistant to proteolytic degradation (trypsin, alpha-chymotrypsin, pronase). However, a significant loss of inhibitory activity to [3H]FNZ binding was observed after acid hydrolysis. Molecular weight estimates based on gel filtration methods were less than 500 dalton, and the maximal ultraviolet absorption peak was at 314 nm. These results suggest that this substance is a new endogenous ligand for the central BZ receptor and may play an important role in regulating the GABAergic tone in the central nervous system.

A novel spectrophotometric assay for lipase activity utilizing cis-parinaric acid.

A new spectrophotometric assay for determining the activity of acylglycerol hydrolases (lipases, E.C. 3.1.1.3) was developed and optimized for yeast lipase (Candida cylindracea). Studies with porcine pancreatic lipase were also conducted and the influence of various detergents and divalent cations on the assay was evaluated. The assay uses cis-parinaric acid (PnA), a naturally occurring fatty acid that has unique spectroscopic properties, and takes advantage of the reversible binding of fatty acids to bovine serum albumin (BSA). Free PnA has an ultraviolet absorption peak at 321.2 nm. When PnA is bound to BSA, however, the peak shifts to 324.2 nm. The assay mixture contains 6 microM PnA, 1 microM BSA, 75 microM triolein, and 0.3 mM taurocholate in a 50 mM tris-HCl buffer with 1 microM EDTA. The release of oleic acid from triolein is monitored over time by measuring the ratio of optical densities (OD) at 319.0 and 329.0 nm. Initially, there is maximum binding of PnA to BSA, and the OD ratio is approximately 1.0. Upon addition of lipase, PnA is displaced from the BSA by oleic acid released from triolein, and the OD ratio increases to a maximum of about 1.8. However, when calcium is present in the reaction mixture an insoluble calcium-PnA complex forms, resulting in a progressive decrease in OD at both 319.0 and 329.0 nm. The kinetic assay described here is simple, rapid, sensitive, reproducible, inexpensive, and it can be adapted to measure the activity of a variety of calcium-independent lipases. Under similar assay conditions, activities for Candida cylindracea lipase obtained with this assay are similar to those obtained with 14C-labelled triolein.

Urinary sodium pump inhibitor raises cytosolic free calcium concentration in rat aorta.

We were able to purify two distinct sodium pump inhibitors to homogeneity from human urine based on [3H]ouabain-displacing activity from intact human erythrocytes. The polar and less polar compounds were eluted off the C18 reverse-phase column with 18% and 31% acetonitrile, respectively. The polar compound cross-reacted very weakly with specific antidigoxin antibody and lacked a characteristic ultraviolet absorption peak between 190 and 300 nm. The less polar compound showed a prominent digoxinlike immunoreactivity and had an ultraviolet spectrum similar to that of digoxin. We examined the effects of these compounds on cytosolic free calcium concentration in cultured rat vascular smooth muscle cells (A10 cells) using the fluorescent calcium chelator fura-2. Only the polar ouabain-displacing compound caused a significant increase, from 108 +/- 7 to 162 +/- 8 nM (n = 6, p less than 0.01), in cytosolic free calcium concentration in A10 cells. The rise in cytosolic free calcium concentration induced by the polar ouabain-displacing compound tended to be slower in onset and more sustained than that induced by arginine vasopressin. In contrast, ouabain and bufalin had no appreciable effects on cytosolic free calcium concentration in A10 cells. These results suggest that the polar ouabain-displacing compound we isolated from human urine may possess a vasoactive property and may play an important role in the modulation of vascular tone.