EFFECT OF IONIZING RADIATION UPON TOTAL DIFFUSE SPECTRAL REFLECTANCE OF ULTRAVIOLET LIGHT BY SKIN

Abstract— Irradiation of guinea-pig skin with X rays and beta particles resulted in decreased total diffuse reflectance (DSR) of 330–400 nm light. Qualitatively, this response resembled that seen after irradiation of the skin of normal guinea-pigs with ultraviolet (UV) radiation of wavelength shorter than 300 nm or that of photosensitized guinea pigs with UV wavelengths longer than 300 nm. We postulate that the transformations which depress the DSR result from energy-transfer processes, independent of the class of radiation. Moreover, they are intimately related to subsequent changes in vascular permeabilities (delayed erythema) which occur after the same radiation exposures that lower the 330–400 nm DSR of skin surfaces.     

Infrared characterization of polymorphism in polybutene-1

The transformations of the polymorphic forms of polybutene-1 (I,II,III) were studied by infrared spectroscopy. Attenuated total reflectance spectra demonstrate that the II → I transformation occurs initially and most rapidly on the film surfaces. Electron irradiation experiments showed the II → I conversion can be suppressed by irradiation. The degree of suppression was dependent on the irradiation dose. Comparison of spectra on irradiation in air and vacuum indicate that radiation-produced radicals are scavenged by oxygen, preventing intermolecular crosslinking and allowing normal expansion of the helix during transformation. In addition, remolding an irradiated sample of II caused immediate conversion to I rather than its return to II as was noted when unirradiated samples are remolded. These observations are related to certain conformational changes in the molecular structure.     

Investigation of Thermal Degradation of PVC in the Solid State

The thermal degradation of PVC powders and the inhibition of this process by cadmium laurate was investigated by the measurement of discoloration, diffuse reflectance spectra, and the quantity of hydrochloric acid formed. Kinetic analysis of the data obtained by us previously showed that both the data of color measurements and those of diffuse reflectance spectra may be used conveniently for the calculation of the number of double bonds formed during the degradation.     

Interfacial Behavior of Benzoic Acid and Phenylphosphonic Acid on Nanocrystalline TiO2 Surfaces

The interfacial behavior of self‐assembled thin films of benzoic acid (BA) and phenylphosphonic acid (PPOA) anchored on TiO₂ surfaces was studied by using temperature‐dependent diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. On the basis of the disappearance of the OH band from the infrared spectra at room temperature, BA and PPOA appear to adsorb onto TiO₂ surfaces through carboxylate and phosphonate groups, respectively. Above 420 °C, DRIFT spectra indicated that both BA and PPOA desorb from TiO₂ surfaces; however, dissimilar desorption behavior could be inferred for BA and PPOA from their temperature‐dependent spectral changes. The benzene ring modes of PPOA remained above 420 °C, whereas those of BA disappeared. Density functional theory calculations showed that the adsorption of BA and PPOA on TiO₂ surfaces corresponded to bidentate bridging geometry on TiO₂ surfaces, and the adsorption of PPOA is stronger than that of BA. The monodentate structures with energy differences of 4.9 and 9.1 kcal mol^?1 from the most stable bidentate structures of BA and PPOA, respectively, from the DFT calculations appeared to be possible, particularly at the high temperatures above 420 °C, as indicated by the intensified OH bands. The geometry of PPOA was also estimated to be more upright standing than that of BA on TiO₂ surfaces, which may lead a rather straight detachment from the TiO₂ surfaces based on the presence of in‐plane ring modes in the DRIFT spectra at the higher temperature.     

Radiation Chemical Studies of Protein Reactions: Dependence of Restorative Amino Acids on Radiation Dose

Abstract

Changes of specific rotation of protein irradiated with Co-60 gamma-rays were restored by some amino acids, such as mono-sodium 1-glutamate. Loss of this recovery effect in some amino acids by irradiation was studied by polarimetry and infrared spectometry. Optical rotation of protein-amino acid solutions increased with an increasing radiation dose given to the amino acids. Changes in optical rotation with irradiation may be due to the loss of the recovery effect of amino acids for the irradiated protein molecule. Changes in infrared spectra increased with an increasing radiation dose given to the amino acids. Such changes in infrared spectra with irradiation may be due to destruction of some radicals in the amino acid molecule.     

Ultraviolet action spectra in perspective: with special reference to mutation

Abstract— Problems of determining action spectra are considered as well as various types of action spectra for U.V. action upon cell activities. U.V. is an effective mutagenic agent producing point mutations and chromosomal changes. U.V. is readily absorbed by superficial layers of cells in tissues; therefore, special experimental procedures are necessary for induction of mutations in animals or plants. U.V. is, however, suitable for mutagenesis in microorganisms because their cells are small, permitting the radiation to reach the nuclei. Action spectrum studies reveal that u.v. mutagenesis results from absorption of the radiation by nucleic acid. The most prominent alteration in DNA following absorption of u.v. is dimerization of pyrimidines, chiefly thymine. Such a change not only retards DNA replication but results in errors (mutations). U.V. mutagenesis therefore depends upon the conditions before, during and after irradiation. Thus immediate post-treatment with visible and long u.v. light splits pyrimidine dimers, thereby reversing impending u.v. mutagenesis. For cells kept in the dark, conditions which prevent DNA replication by interfering with the metabolism of the cell provide time for dark repair of the DNA lesion and so for reversal of the impending mutation.     

Molecular structure and hydrogen bonds in solid dimethylol propionic acid (DMPA)

The H-bonds in dimethylol propionic acid (DMPA) are investigated through the spectra changes between -150 and 180 degrees C, the spectra comparison before and after the pendent carboxylic group was neutralized as well as after DMPA was partly deuterated. Vibrational bands assignment is proposed based on the group frequency, band shape, intensity and the crystal structure. It was found that the highly crystallized DMPA is also highly H-bonded with the obvious crystal relating bands besides the typical H-bonded characteristic bands of both alcohols and carboxylic acids. The packing mode of carboxylic acid is similar to long-chain polymers to some extent but possesses the dimer spectra characteristic, especially still showing the prominent out-of-plane bending vibrational band gammaOH. The three hydroxyls, including the carboxylic hydroxyl, are all in the different H-bond states, showing three H-bonded hydroxyl bands with different frequencies. The frequency, intensity and shape of nuOH relates not only to OH bond length, but also to H-bond length as well as the bond angle. The H-bond in carboxylic hydroxyl is more sensitive to temperature changes and deuteration whereas the two primary hydroxyls form another H-bond pattern after DMPA was neutralized. It was also found that the possible overtone of gammaOH appears at lower temperature.     

应用漫反射红外光谱技术优化2-聚苯乙烯磺酰胺基乙醇树脂的合成

本文采用漫反射红外光谱法优化一种新的固相合成载体2－江西 乙烯磺酰胺基乙醇树脂的合成。聚苯乙烯磺酰氯树脂在有或没有溶剂和／或催化剂存在下与乙醇铵反应得到2－聚苯乙烯磺酰胺基乙醇树脂。漫反射红外光谱跟踪整个反应过程。结果表明，漫反射红外光谱技术是优化制备新的功能基化聚合物条件的有力工具。2－聚苯乙烯磺酰胺基乙醇树脂的优化制备条件是：聚苯乙烯磺酰氯，乙醇胺在60℃反应30min。     

Luminescence quantum yield determination for molecules adsorbed onto solid powdered particles.

A new methodology for the determination of the fluorescence quantum yield of dyes adsorbed onto microcrystalline cellulose is presented and applied to rhodamine 101, cresyl violet and auramine O. It is based on a previously reported method by Ruetten and Thomas (J. Phys. Chem., 1998, 102, 598-606), which is not applicable to the dyes used in the present study. It uses ground-state diffuse reflectance spectra obtained with and without filters, which prevents the luminescence of the dye from reaching the integrating sphere and the photodetector. New equations are presented here, correcting for the fluorescence emission of the dye, which depends on the detector sensitivity. Cut-on filters, which have a transmittance close to unity in the absorption region, and close to zero in the emission region, of the dye are used to obtain corrected reflectance spectra. The influence of the substrate was also taken into account. This methodology may be applied to other probes and surfaces or emissions of a different nature (i.e., phosphorescence or delayed fluorescence), and constitutes a very simple and general procedure to solve the important problem of luminescence quantum yield determination of probes adsorbed onto solid powdered surfaces.     

Extraction of diffuse reflection spectrum on reflectance spectroscopy for solid or powder surfaces

Reflectance spectroscopy usually produces distorted spectra because it is arbitrarily composed of two different types of reflectance, specular reflectance and diffuse reflectance. That is why this has been an annoying problem for reflectance spectroscopists. In this report, we studied the extraction of only the diffuse reflectance spectra from several reflectance spectra using redundant multiple spectral information, non-negative transformation of the recorded spectra and information processing as the multi-curve resolution. As a result, we found that we could estimate just the diffuse reflectance spectral profile.     

Improving enzymatic hydrolysis of industrial hemp (Cannabis sativa L.) by electron beam irradiation

The electron beam irradiation was applied as a pretreatment of the enzymatic hydrolysis of hemp biomass with doses of 150, 300 and 450 kGy. The higher irradiation dose resulted in the more extraction with hot-water extraction or 1% sodium hydroxide solution extraction. The higher solubility of the treated sample was originated from the chains scission during irradiation, which was indirectly demonstrated by the increase of carbonyl groups as shown in diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) spectra. The changes in the micro-structure of hemp resulted in the better response to enzymatic hydrolysis with commercial cellulases (Celluclast 1.5L and Novozym 342). The improvement in enzymatic hydrolysis by the irradiation was more evident in the hydrolysis of the xylan than in that of the cellulose.     

The effect of ultraviolet radiation upon osmoregulation in Paramecium

Abstract Paramecium multimicronucleatum was irradiated with U.V. in solutions of differing osmotic pressures and ionic content. The rates of contraction and the diameters of the anterior contractile vacuoles were measured and changes in the volumes of solution entering the contractile vacuoles upon U.V. irradiation for paramecia maintained in solutions of differing ionic content were calculated. The volume of fluid entering the contractile vacuoles of paramecia irradiated (1) in standard balanced salt solution (SBSS) was regulated by a compensatory mechanism at lower U.V. doses but increased after relatively large U.V. doses; (2) in distilled water, increased after much smaller U.V. doses; (3) in isotonic balanced salt solution, showed little change upon irradiation. Increased osmotic pressure (with added sucrose) was found to reduce u.v.-induced blistering of the pellicle, but in general U.V. damage was similar to that of paramecia in solutions of identical ionic content but lacking sucrose. Paramecia in SBSS with added sucrose to make it isomotic to the interior of the cell ruptured only after doses larger than for paramecia in SBSS lacking sucrose. Cell rupture of paramecia in solutions containing high CaCl₂ concentrations generally occurred later than for those in SBSS. High KCI concentration (unbalanced salt solution) in the presence of high CaCl₂ concentration provided some protection from U.V. irradiation to the paramecia. High NaCl concentration (unbalanced salt solution) in the presence of high CaCl₂ concentration appeared to increase u.v. damage to paramecia. Paramecia were most resistant to u.v. irradiation, as judged by the above criteria, when present in balanced salt solution enriched with calcium, thus simulating pond water.     

Determination of Bovine Hemoglobin by Near-Infrared Diffuse Reflectance Spectroscopy with Novel Adsorption Preconcentration

A method for the quantitative determination of bovine hemoglobin in dilute solution was developed using adsorption preconcentration and near-infrared diffuse reflectance spectroscopy. An adsorbent, designated as multicarbonyl polymer-grafted silica particles, was prepared for the preconcentration of bovine hemoglobin in dilute solution. Under neutral conditions, the adsorption efficiency exceeded 98% within 20?min. After the preconcentration of bovine hemoglobin on the adsorbent, the near-infrared spectrum was measured in diffuse reflectance mode and a partial least squares model was constructed for quantitative prediction. Samples were analyzed in the presence of amino acid, albumin bovine V, D-glucose, and metal ions as potential interferences. The results show that bovine hemoglobin was selectively determined. The correlation coefficient between the predicted concentrations and the reference values was 0.9911, and the recoveries were from 86.4 to 111.2% for validation samples with concentrations between 2.1 and 30.0?mg?L^?1. Therefore, the determination of bovine hemoglobin was achieved by near-infrared diffuse reflectance spectroscopy combined with preconcentration and chemometric modeling.     

DNA and protein changes caused by disease in human breast tissues probed by the Kubelka-Munk spectral functional

Malignant, fibroadenoma, normal and adipose breast tissues were studied using diffuse reflectance spectroscopy. The absorption spectra of the breast tissues were extracted from the diffuse reflectance spectra using the Kubelka-Munk function (K-M function). The spectral features of the K-M function were identified and compared with those of the absorption spectra. The spectral features of the K-M function were assigned to DNA, protein, beta-carotene and hemoglobin (oxygenated and deoxygenated) molecules in the breast tissue. The amplitudes of the K-M function averaged from 275 to 285 nm and from 255 to 265 nm and were found to be different for malignant, fibroadenoma and normal tissues. These differences were attributed to changes in proteins and DNA. A set of critical parameters was determined for separating malignant tissues from fibroadenoma and normal tissues. This approach should hold for other tissue types such as cervix, uterus and colon.     

Visible-Light Activities of Erbium Doped BiVO4 Photocatalysts

Er-doped BiVO₄ composite photocatalyst was hydrothermal synthesized and characterizedby X-ray powder diffraction, scanning electron microscopy, energy-dispersive X-ray Spectroscopy, X-ray photoelectron spectroscopy, and UV-Vis diffuse reflectance spectra techniques. The activity of the catalyst was determined by oxidative decomposition of methyl orange in aqueous solution under visible-light irradiation. X-ray photoelectron spectroscopy and energy-dispersive X-ray Spectroscopy analysis revealed that the doped Er existed in the form of Er₂O₃. It also showed that the Er doping can enhance the visible-light absorption abilities of catalysts and their visible-light-driven photocatalytic activities in comparison with those of pure BiVO₄.     

Spin-orbit electronic states of octahedral Pt-group d 6 complexes as derived from reflectance spectra and ligand field calculations

The 90 K diffuse reflectance spectra of some octahedral Rh(III), Ir(III) and Pt(IV) complex compounds with chloride, thiocyanate and amine ligands are reported. The spectra show in the visible and near ultraviolet distinct bands due to spin-orbit components of singlet-triplet d-d transitions which are explained by ligand field calculations including spin-orbit coupling considering all possible d-electron configurations. Model parameter sets are obtained by fitting the measured band peaks to possible transitions between calculated energy levels. For some of the bands the vibrational structure could be resolved which is assigned to metal-ligand stretching vibrations of the electronically excited complex octahedra with vibrational fundamentals lower than those of the ground state.     

Irradiation effects on canvas oil painting: Spectroscopic observations

“Winter” oil painting, by Romanian contemporary artist George Alexandrescu was used as experimental model for the substantiation of gamma radiation treatment, as the best choice to stop the biological attack of paintings. In this purpose, spectroscopic and colorimetric methods were used to analyse in situ, non-destructively and non-contact, the experimental model before and after ⁶⁰Co gamma irradiation. Chemical structure and colour changes were monitored by FTIR, FT-Raman and Vis reflectance spectroscopy. Negligible Infrared spectral transformations have been observed after irradiation. Furthermore, it was found that gamma irradiation did not induce any significant colour alterations. Insignificant structural and colour changes observed, recommend the use of gamma irradiation in the disinfection of oil paintings.     

乙烯在Pt/Pt4+-TiO2上的可见光降解

以TiO2为主的光催化氧化技术存在太阳能利用率低(～5％)和光量子转化效率低(～4％)等缺点，使其工业应用受到制约，人们尝试用过渡金属离子掺杂和贵金属表面修饰等技术来提高催化剂对太阳能的利用率和光量子的转化效率，但目前将铂离子掺杂和铂金属表面修饰技术结合用于光催化     

Organocatalytic Enantioselective Protonation for Photoreduction of Activated Ketones and Ketimines Induced by Visible Light

The first catalytic asymmetric photoreduction of 1,2‐diketones and α‐keto ketimines under visible light irradiation is reported. A transition‐metal‐free synergistic catalysis platform harnessing dicyanopyrazine‐derived chromophore (DPZ) as the photoredox catalyst and a non‐covalent chiral organocatalyst is effective for these transformations. With the flexible use of a chiral Brønsted acid or base in H⁺ transfer interchange to control the elusive enantioselective protonation, a variety of chiral α‐hydroxy ketones and α‐amino ketones were obtained with high yields and enantioselectivities.     

Porphyrin bleaching and PDT-induced spectral changes are irradiance dependent in ALA-sensitized normal rat skin in vivo

Photobleaching kinetics of aminolevulinic acid-induced protoporphyrin IX (PpIX) were measured in the normal skin of rats in vivo using a technique in which fluorescence spectra were corrected for the effects of tissue optical properties in the emission spectral window through division by reflectance spectra acquired in the same geometry and wavelength interval and for changes in excitation wavelength optical properties using diffuse reflectance measured at the excitation wavelength. Loss of PpIX fluorescence was monitored during photodynamic therapy (PDT) performed using 514 nm irradiation. Bleaching in response to irradiances of 1, 5 and 100 mW cm-2 was evaluated. The results demonstrate an irradiance dependence to the rate of photobleaching vs irradiation fluence, with the lowest irradiance leading to the most efficient loss of fluorescence. The kinetics for the accumulation of the primary fluorescent photoproduct of PpIX also exhibit an irradiance dependence, with greater peak accumulation at higher irradiance. These findings are consistent with a predominantly oxygen-dependent photobleaching reaction mechanism in vivo, and they provide spectroscopic evidence that PDT delivered at low irradiance deposits greater photodynamic dose for a given irradiation fluence. We also observed an irradiance dependence to the appearance of a fluorescence emission peak near 620 nm, consistent with accumulation of uroporphyrin/coproporphyrin in response to mitochondrial damage.