Spectroscopic evaluation of painted layer structural changes induced by gamma radiation in experimental models

The degradation of cultural heritage objects by insects and microorganisms is an important issue for conservators, art specialists and humankind in general. Gamma irradiation is an efficient method of polychrome wooden artifacts disinfestation. Color changes and other modifications in the physical chemical properties of materials induced by gamma irradiation are feared by cultural heritage responsible committees and they have to be evaluated objectively and precisely. In this paper FTIR and FT-Raman spectroscopy methods were used to investigate the structural changes in some experimental models of tempera paint layers on wood following 11 kGy gamma irradiation at two dose rates. Radiation chemistry depends on the particular pigment, matrix formed by protein, resin (in case of varnished samples) and water presence. For the majority of painted layer in experimental models very small spectral variations were observed. Small changes in the FTIR spectra were observed for the raw sienna experimental model: for the higher dose rate the egg yolk protein oxidation peaks and the CH stretching bands due to lipids degradation products increased.     

Spectroscopic evidence of thermally induced metamorphosis in ethenylene-bridged periodic mesoporous organosilicas

Spectroscopic evidence of the thermally induced generation of multifunctional mesoporous materials through metamorphism within the pore walls of ethenylene-bridged PMOs is presented.     

Gamma radiation induced effects on slaughterhouse wastewater treatment

A preliminary study using gamma radiation on slaughterhouse wastewater samples was carried out. Chemical oxygen demand (COD), biochemical oxygen demand (BOD) and total suspended solids (TSS) results were obtained at a dose rate of 0.9 kGy h⁻¹. A decrease of COD, BOD and colour was observed after irradiation at high absorbed doses. The microbiological results, following irradiation in the same conditions, correlated with the BOD results. The results obtained highlight the potential of this technology for wastewater treatment.     

Spectroscopic evidence for the formation of goldfingers

Gold(I) has long been used in the treatment of rheumatoid arthritis, but the therapeutically relevant biological targets of gold(I) are not well understood. Here, we report the results of a spectroscopic investigation into the formation of goldfingers. By exploiting a thiolate to gold charge-transfer band in the UV, we observed that gold(I) interacts with zinc finger peptides with a stoichiometry of one gold ion for each two cysteine residues, forming 1:1, 1.5:1, and 2:1 adducts with zinc finger peptides containing CCHH, CCHC, and CCCC donor sets, respectively. In addition, circular dichroism experiments provided evidence that goldfingers are more ordered than the corresponding metal-free peptides but do not exhibit the canonical zinc finger structure.     

Comparison of degradation effects induced by gamma radiation and electron beam radiation in two cable jacketing materials

The radiation degradation behavior of commercial low density polyethylene (LDPE) and ethylene–vinylacetate (EVA) cable materials has been investigated. The changes of mechanical properties, thermooxidative stability and density exhibit different radiation stability towards ⁶⁰Co-gamma radiation and 160 keV electron beam radiation. This difference reflects much higher penetration of the gamma radiation through the polymeric material as a function of sample thickness. These results are discussed with respect to the role of beta radiation during design basis events in a nuclear power plants. In case when total accidental design basis event (DBE) dose (involving about 80% soft beta radiation) is simulated by ⁶⁰Co-gamma radiation the conservatism is reached.     

Determination of selenium in animal tissue samples using radioisotope induced X-ray fluorescence

A summary of sources of background affecting gamma-ray spectrometers and methods for eliminating each are discussed, along with practical cost/benefit ratios. Background contributed by samples generally defines practical levels for system background. The practical bottom line can be obtained for relatively modest costs. A realistic bottom line is attained in underground systems when the major contributions to the background come from cosmogenically produced⁶⁸Ge and double-beta decay of⁷⁶Ge in the detector. The true bottom line is reached with isotopically enriched detectors that eliminate these two chemically inseparable radioactive impurities. Data from isotopically enriched detectors are presented.     

Ionizing radiation induced effects on medicinal vegetable products. Cascara bark

The effects of gamma irradiation on cascara bark were studied. Induced degradation products and modification in cascaroside ratio were investigated by a dedicated HPLC method. The presence of free radicals was evaluated by EPR technique. Both HPLC and EPR measurements were performed at different times up to four months after the irradiation process.     

Study on the radiation degradation of polyether-polyurethane induced by electron beam

Polyether-urethane samples were irradiated at the dose range from 10 to 2000 kGy by 2 MeV electron beams. Volatile species from the polymer degradation were analyzed quantitatively and qualitatively with GC/MS. Thermal properties and micro-phase separation of the samples were examined by TG and the morphology was studied by TEM and SEM. The results show that the irradiated polyether-polyurethane evolves CO₂, H₂, CH₄ and C₂H₆, etc. The thermal stabilities between the hard and soft segments in the irradiated samples are different. At high doses, the phase separation in the sample is predominant and the hard segment of sample is more stable. The dose rate affects the soft segment of the irradiated sample much more.     

分光光度法测定合金钢中镍含量

镍是合金钢中重要元素之一 ,它可以增加钢的的弹性、延展性和抗腐蚀性 ,使钢具有较高的机械性能。目前测定合金钢中的镍 ,不论是 JIS1 2 1 6-82 [1] 法还是 GB2 2 3,2 4 - 82 [2 ] 法 ,均需沉淀或萃取 ,使镍与合金钢中其它元素分离 ,因此手续复杂 ,操作时间长 ,而且使用试剂较多。本法用磺基水杨酸掩蔽铁、铜、铝等元素后直接用分光光度计测定镍。此法不需沉淀或萃取分离 ,可用于测定进口合金钢中的镍含量。1　实验部分1 .1　试剂与仪器过硫酸铵 ( 343g/L) ,丁二酮肟 ( 1 0 g/L) ,氢氧化钠 ( 5 0 g/L) ,磺基水杨酸 ( 32 4 g/L) ,镍标准…     

On the variation of physicochemical properties of starch samples treated by microwave radiation

Acid-base properties of potato starch suspensions, unirradiated and exposed to microwave radiation, and also comparative structural and mechanical properties of their cooked gels were studied by the methods of electronic photography of starch grains, direct potentiometry, and potentiometric titration.     

Polymerization of aqueous formaldehyde induced by ionizing radiation

In this work we examined the formation of polymeric material from the radiation-induced reactions of aqueous formaldehyde. The polymers obtained by this procedure are very different from those formed by thermal or UV polymerization. Two polymeric materials precipitated between 0.8 and 1.3 MGy. Although these polymers have the same chemical composition (C₂H₃O), infrared spectrum, and NMR spectrum, they differ in density, color and melting point. The interconversion of the polymeric materials increase when the dose is raised.     

Formation of peroxynitrite induced by spark plasma radiation

The formation of peroxynitrite (ONOO^?) in water by the action of plasma UV radiation from spark discharge in air has been studied. Solutions with pH₀ 3.11–12.86 have been treated. In all cases, the pH has been observed to decrease immediately after the treatment and for the following 14 days. An absorption line characteristic of peroxynitrite (λ = 302 nm) appears in the spectrum by the fourth to fifth day after the treatment and reaches a maximum by the 10th–12th day. The appearance of peroxynitrite a few days after the treatment can be caused by the formation of a substance X during a radiation pulse at a high density of active species, which decomposes according to the scheme X → ONOO^? → NO ₃ ^? and has a lifetime of about 10 days. The maximal yield of peroxynitrite is (1.2 ± 0.5) × 10^?2 mol/L.     

Temperature effects on radiation induced phenomena in polytetrafluoroetylene (PTFE)-Change of G-value

Temperature dependencies on the radiation induced phenomena and G-value of polytetrafluoroethylene (PTFE) have been studied in a temperature range 77–653 K. It is well known that main chain scission occurs very effectively below the melting temperature of PTFE (600 K). We have found in our experiments that G-value of chain scission increases significantly with increasing irradiation temperature, until 600 K. In addition to that, we have realized that crosslinking occurs by irradiation in the molten state at 613 K (Tabata, 1992; Oshima et al., 1995; Tabata et al., 1996). In the molten state, G-value of crosslinking was found to be 0.35 (number of crosslinking/100 eV absorption), as a lower limit, and the apparent G-value of chain scission is drastically reduced. Above 633 K, radiation induced crosslinking mainly occurs, however parallel thermal depolymerization or decomposition takes place to some extent.     

Bystander effects in cell death induced by photodynamic treatment UVA radiation and inhibitors of ATP synthesis

Confluent layers of MDCK II cells were treated with four different photosensitizers (a purified version of hematoporphyrin derivative [Photofrin], tetra(3-hydroxyphenyl)porphine [3-THPP], meso-tetra(4-sulphonatophenyl)porphine [TPPS4] and ALA-induced Protoporphyrin IX) and irradiated with blue light, with UVA without exogenous photosensitizers, or incubated with the metabolic inhibitors carbonyl cyanide m-chlorophenylhydrazone and 2-deoxy-D-glucose. Necrotic and apoptotic cells were detected about 4 h later by fluorescence microscopy. Dead cells appeared in distinct clusters in the confluent layers. The number of dead cells in these clusters was determined by manual counting and image analysis. Forty-one of the 43 experimental distributions of dead cells in clusters were found to be significantly different from a Monte Carlo simulation of the distribution of independently inactivated cells. However, a Monte Carlo simulation model, assuming that each dead cell increased the probability of inactivation of adjacent cells, fitted 34 of the 43 observed distributions of dead cells in clusters, indicating a significant bystander effect for all the investigated treatments. The bystander-effect model parameter, defined as a cell's increase in probability of dying when it has dead neighbors, was significantly lower for 3-THPP-PDT and TPPS4-PDT than for Photofrin-PDT, ALA-PDT and treatment with metabolic inhibitors.     

Identification evidence unraveled by strict proteomics rules toward forensic samples

Snake venom is a complex mixture of proteins and peptides secreted by venomous snakes from their poison glands. Although proteomics for snake venom composition, interspecific differences, and developmental evolution has been developed for a decade, current diagnosis or identification techniques of snake venom in clinical intoxication and forensic science applications are mainly dependent on morphological and immunoassay. It could be expected that the proteomics techniques directly offer great help. This work applied a bottom-up proteomics method to identify proteins’ types and species attribution in suspected snake venom samples using ultrahigh-performance liquid chromatography–quadrupole-electrostatic field Orbitrap tandem mass spectrometric technique, and cytotoxicity assay was amended to provide a direct evidence of toxicity. Toward the suspicious samples seized in the security control, sample pretreatment (in-sol and in-gel digestion) and data acquisition (nontargeted and targeted screening) modes complemented and validated each other. We have implemented two consequent approaches in identifying the species source of proteins in the samples via the points of venom proteomics and strict forensic identification. First, we completed a workflow consisting of a proteomics database match toward an entire SWISS-PROT (date 2018-11-22) database and a result-directed specific taxonomy database. The latter was a helpful hint to compare master protein kinds and reveal the insufficiency of specific venom proteomics characterization rules. Second, we suggested strict rules for protein identification to meet the requirements of forensic science on improved identification correctness, that is, (1) peptide spectrum matches confidence, peptide confidence, and protein confidence were both high (with the false-discovery ratio less than 1%); (2) the number of unique peptides was more than or equal to two in one protein, and (3) within unique peptides, which at least 75% of the ∆m/z of the matched y and b ions were less than 5 ppm. We identified these samples as cobra venom containing 10 highly abundant proteins (P00597, P82463, P60770, Q9YGI4, P62375, P49123, P80245, P60302, P01442, and P60304) from two snake venom protein families (acid phospholipase A2 and three-finger toxins), and the most abundant proteins were cytotoxins.     

Spectroscopic studies into the influence of UV radiation on elastin in the presence of collagen

An investigation into the influence of UV irradiation on elastin hydrolysates in the presence of collagen was carried out using UV-Vis spectroscopy and spectrofluorometry. It was found that the absorbance of elastin hydrolysates in solution increased during irradiation more than the absorbance of the elastin/collagen blend. The fluorescence of elastin hydrolysates was observed at 305nm and at 380nm after excitation at 270nm. For the elastin/collagen mixture in solution, fluorescence spectrum shows only one maximum at 305nm. UV irradiation caused fluorescence fading at 305nm. For irradiated elastin the fluorescence at 305nm decreased faster than for the irradiated elastin/collagen mixture. The maximum of the fluorescence peak was shifted for elastin by 4nm, whereas for the elastin/collagen blends the shift was only 1-2nm. All the obtained results point out the ability of mixing elastin and collagen, and suggest that the elastin/collagen mixture in solution is less sensitive to UV irradiation than elastin hydrolysates alone.     

Laser induced photoacoustic spectroscopy in liquid samples: temperature and solvent effects

Summary Laser induced photoacoustic spectroscopy (LIPAS) has been confirmed as an analytical tool, suitable for the determination of inorganic and organic species in aqueous and organic solvents, reaching detection limits two orders of magnitude lower than those obtained with conventional spectrophotometry.A significant influence of the solvent on the enhancement of the magnitude of the LIPAS response waveform of the piezoelectric detector has been found experimentally for inorganic species (neodymium ions) and organic compounds (e.g. -carotene and the cytochrome c), when water was replaced by organic solvents. This is particularly true, when a laser excitation wavelength above 500 nm was used, where the absorption coefficient for H₂O increases drastically.Furthermore, the temperature dependence of the magnitude of the LIPAS signal has been measured, in the range between 20–70°C in samples containing Nd³⁺,-carotene and the macromolecule cytochrome c in various aqueous and organic (polar and non-polar) solvents (H₂O, HClO₄, acetone, ethanol and petrol ether). A very strong enhancement of the LIPAS response was observed with increasing temperature (a factor of two in an interval between 20 and 40°C) for all inorganic and organic substances in aqueous solution. On the other hand, in polar and non-polar organic solvents only a slight decline of the signals of about 20% was found over the same temperature range.     

Spectroscopic studies into the influence of UV radiation on elastin hydrolysates in water solution

An investigation into the influence of UV irradiation on elastin hydrolysates dissolved in water was carried out using UV-Vis spectroscopy and spectrofluorometry. It was found that the absorption of elastin hydrolysates in solution increased during irradiation of the sample. For fluorescence of elastin hydrolysates we observed both, a decrease and increase of this value during irradiation of the sample. After UV irradiation of the elastin solution we observed a minor increase of overall absorption, most notably between 250 nm and 280 nm. Moreover, after UV irradiation a wide peak emerged between 290 nm and 310 nm with maximum at about 305 nm. The new peak suggests that new photoproducts are formed during UV irradiation of elastin hydrolysates. The fluorescence of elastin hydrolysates was observed at 305 nm and at 380 nm after excitation at 270 nm. UV irradiation caused fluorescence fading at 305 nm and 380 nm. After 30 min of irradiation a new broad weak band of fluorescence, attributable to new photoproducts, emerged in the UV wavelength region with emission maximum between 400 nm and 500 nm.