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Flavor plays an essential role in the sensory and consumer acceptance of complementary food products for infants and young children. To improve the quality of infant complementary food nutrition powder, the volatile flavor substances in nutrition powder and those with kiwifruit powder, orange powder and quinoa flour were analyzed by headspace-gas chromatography-ion migration spectrometry. A total of 61 compounds were identified in the nutrition powder of two different formulations, of which 58 could be clearly identified. The study showed that supplementation with kiwifruit powder, orange powder and quinoa flour could inhibit the production of (E)-2-nonenal, 2-octanone, delta-nonalactone, ethyl disulfide. The inhibitory rate of (E)-2-nonenal was the highest, achieving 37.00 ± 3.07%, delta-Nonalactone was 28.86 ± 3.69% and 2-octanone was 14.12 ± 0.46%. It may delay their conversion to acids, aldehydes, ketones, and other compounds. In addition, the intensity of the saturated acids signal in the YYB-300 was different significantly than the YYBS-300, which was 1.99 ± 0.07 cm−1 in the YYB-300 group, 1.941 ± 0.12 cm−1 in the YYBS-300 group, severally. The results of electron spin resonance (ESR) showed that the free radical content material of the YYB-300 group was 6.57 × 105, but the free radical content material of YYBS-300 group was low significantly, which used to be 6.18 × 105. The consequence of Fourier transforms infrared spectroscopy (FTIR), and electron spin resonance (ESR) confirmed that the addition of kiwifruit powder, orange powder and quinoa flour maybe delay the lipid oxidation. The results also provided a theoretical basis for improving the flavor quality and nutritional quality of infant nutrition powder. [ABSTRACT FROM AUTHOR]

Industrial needle-coke samples are studied. Their paramagnetic characteristics are determined over a broad range of magnetic fields. For some samples, no pronounced signal from the microwave resonator is observed. This indicates that the conversion of the molecular structure to coke is complete in those samples. For some samples, the ESR spectra contain two sharply resolved signals from centers associated with aliphatic and aromatic fragments. That indicates incomplete structural transformation. [ABSTRACT FROM AUTHOR]

Electron spin resonance imaging (ESRI) has been developed to detect the spatial contribution of free radicals in recent years, but all of these studies are used in animal systems and almost of them using exogenous spin probes and only a few to study the endogenous free radicals in vivo. However, there is no report about the endogenous free radical three-dimensional (3D) EPRI in plant because of low concentration of endogenous free radicals and low resolution of the L-band ESRI. Recently, we have developed the imaging resolution better than 200 μm which is higher 10 times than L-band (about 1-3 mm) and the sensitivity is higher about 1000 times than that of L-band ESRI. Using this system and spin trapping technique, we studied spatial contribution of the endogenous nitric oxide (NO) radical generation in wheat leaves and got a clear 3D ESRI picture and CT (computed tomography) of NO of a wheat leaf. This imaging picture shows a clear spatial distribution of NO free radicals in the leaf. This is the first 3D ESRI of endogenous NO free radical generated in plant in the world. We have also studied the distributions of NO generation in different plants from different species with different shapes and it is shown that this is a convenient method to study the endogenous free radicals in plants. [ABSTRACT FROM AUTHOR]

High levels of reactive oxygen (ROS) and nitrogen (RNS) species can lead to the destruction of extracellular matrix facilitating tumor progression. ROS can activate matrix metalloproteinases (MMP), damage DNA and RNA. Therefore, the levels of MMP, ROS and RNS can serve as additional prognostic markers and for the estimation of the effectiveness of tumor therapy. Concerning gastric cancer, the prognostic role of MMP, its connection with the cancer staging remains controversial and correlations between the activity of MMP with the ROS and RNS levels are insufficiently confirmed. Superoxide generation rates, nitric oxide (NO) levels, concentrations of active forms of matrix metalloproteinases MMP-2 and MMP-9 in tumor and adjacent tissues of patients with stomach cancer at different disease stages were measured by electron spin resonance (ESR) including spin-trapping and polyacrylamide gel zymography. It is shown that the activity of MMP-2 andMMP-9 in tumor tissue correlate with the superoxide radicals generation rate and NO levels (r=0.48÷0.67, p < 0.05). The activity of MMP-2 and MMP-9 in tumor tissues and superoxide radical generation rates correlate positively with the stage of regional dissemination (r= 0.45 and 0.37, correspondingly, p<0.05), butMMP-2 and MMP-9 activity inversely depends on distant metastatic degree of stomach cancer (r = 0.58; p<0.05). Additionally, the feasibility of ESR to locally determine oxidative stress is demonstrated. [ABSTRACT FROM AUTHOR]

Methanol-to-olefin (MTO) conversion over various zeolites with different topologies, Si/Al molar ratios, and crystallite sizes were investigated to verify the effects of pore shape and size, acidity, and external surface area on the catalytic activity, product selectivity, and deactivation. The IR and electron spin resonance (ESR) study of zeolite catalysts used in MTO also proceeded to deduce the active intermediates formed in their cages or pores. The zeolites with 8 membered-ring (MR) pore entrances such as CHA, ERI, LTA, and UFI commonly exhibited high selectivity to lower olefins due to their small entrances, but the CHA catalyst with the smallest cage maintained its activity longer than other 8MR zeolites. The slow condensation of polymethylbenzene (PolyMB) to polyaromatic hydrocarbons (PAH) on MOR zeolite with a high Si/Al molar ratio due to its low concentration of strong acid sites resulted in a slow deactivation. The extremely small crystallites of H-SAPO-34 and H-ZSM-5 less than 100 nm showed an adverse effect in MTO; while the large crystallites above 1,000 nm also exhibited poor catalytic performance because of their small external surface. The study of IR regarding the adsorbed and occluded materials on zeolites demonstrated the effect of pore shape and size on the active intermediates: the zeolites with larger pores and cages allowed the formation of alkylbenzenes with long alkyl groups which preferred to be condensated to PAH. The well-resolved hyperfine splitting of ESR spectra observed on H-SAPO-34 used in MTO clearly illustrated the presence of hexamethylbenzenium radical cations. The small intersections of phosphorous-modified H-ZSM-5 allowed the formation of tetramethylbenzenium radical cations in MTO. The formation of PolyMB radical cations, their role as active intermediates and the effect of topology, acidity, and crystallite size of zeolites on their deactivation were discussed. [ABSTRACT FROM AUTHOR]

Cobalt oxide (CoO) nanoparticles were synthesized by a novel microwave-assisted decomposition reaction of the cobalt nitrate hexahydrate, Co(NO)⋅6HO. While most of the traditional methods for the preparation of CoO are at relatively high temperature, microwave-assisted decomposition was adapted to have better control in the production of CoO nanoparticles. The temperature dependence of the magnetic properties for the CoO was investigated by vibrating sample magnetometer (VSM) and electron spin resonance (ESR) techniques. VSM and ESR measurements have shown a phase transition occurring at around 31 K, as the antiferromagnetic transition temperature for the bulk CoO crystal exhibits almost the same value. The average particle size of the sample at around the transition temperature is estimated as 2.015 nm. The title compound was characterized and identified by an x-ray powder diffraction (XRD). [ABSTRACT FROM AUTHOR]

Some antioxidant anesthetics directly inhibit lipid peroxidation mediated via the generation of reactive oxygen species (ROS). To date, the scavenging effects of midazolam on ROS have not been directly assessed. We investigated the inhibitory effect of midazolam on ROS [hydroxyl radical (HO) and superoxide (O)] by in vitro X-band electron spin resonance with the spin-trapping agent 5,5-dimethyl-1-pyrroline- N-oxide. Our results indicated that HO and O were not affected by midazolam at clinically relevant concentrations, but were directly scavenged by midazolam at high concentrations (i.e., >4.6 and >1.5 mM, respectively). [ABSTRACT FROM AUTHOR]

The aim of the present study is to determine the anti-proliferative activity of 6- o-palmitoyl- l-ascorbic acid (Asc6Palm) that is a lipophilic derivative of l-ascorbic acid (Asc), on human tongue squamous carcinoma HSC-4 cells by combined use of hyperthermia in comparison to Asc. Asc6Palm or Asc were administered to HSC-4 cells for 1 h, to which hyperthermia at 42 °C was applied for initial 15 min. After further 1-72 h incubation at 37 °C, cell proliferation was determined with Crystal Violet staining. Ascorbyl radical (AscR) in HSC-4 cell suspension was measured by electron spin resonance (ESR), and cell morphology was observed with scanning electron microscopy (SEM). At 37 °C, 4 mM Asc or 0.35 mM Asc6Palm were enough to suppress proliferation of HSC-4 cells. By combined use of hyperthermia at 42 °C, cell proliferation was decreased when compared to 37 °C. After Asc of 4 mM was incubated with HSC-4 cell suspensions at 37 °C or 42 °C for 0-180 min, the signal intensity of ascorbyl radical (AscR) by ESR was not different regardless of the presence or absence of cells at 37 °C, whereas AscR signal was enlarged in the presence of HSC-4 cells at 42 °C. It was suggested that oxidation of Asc occurred rapidly in HSC-4 cells by hyperthermia, and thereby enhanced the anti-proliferative activity. By SEM observation, the surface of HSC-4 cells treated with Asc6Palm revealed distinct morphological changes. Thus, the combined regimen of Asc6Palm and hyperthermia is expected to exert a marked antitumor activity. [ABSTRACT FROM AUTHOR]

Possibility of photostimulated luminescence (PSL) and electron spin resonance (ESR) to detect γ-irradiation of jujube ( Zizyphus jujuba) was investigated. The jujube samples were exposed to γ-irradiation at doses of 1, 3, 5, and 10 kGy. The PSL results showed that jujube exposed to at 1 kGy or more had a photon count of greater than 5,000 count/60 sec (positive), while the non-irradiated jujube yielded a photon count of less than 700 photon count/60 sec (negative). However, physical parameters (light exposure, storage, and thermal treatment) of irradiated jujube samples gave a strong effect on the PSL signal, resulting in decrease of the photon counts from the initial counts. ESR spectroscopy analysis of irradiated jujube revealed specific signals derived from cellulose radicals, and irradiation caused a significant increase in the ESR signal intensity of the jujube samples without any changes in the spectral patterns. Light exposure, storage, and thermal treatment of jujube resulted in significant decreases in the ESR signal intensities of cellulose radicals. [ABSTRACT FROM AUTHOR]

In order to explore the production of hydroxyl radical (·OH) in a confined space, a novel ozone-light irradiation system is constructed in this study, and the ·OH radical is measured by spin-trapping electron spin resonance (ESR) method in which 5,5-dimethyl-1-pyrroline- N-oxide (DMPO) is selected as the spin-trap. Several influence factors including the light intensity, the irradiation time and DMPO mass concentration are discussed. The results show that in this experimental system, with DMPO mass concentration of 1g/L and the irradiation time of 30 min, the ·OH radical can be best captured. Besides, both wavelength and intensity of the irradiation light could effect the generation of ·OH radical. These results are of great importance to further study the sterilization effect of ·OH radical in confined space. [ABSTRACT FROM AUTHOR]

Conventional electron paramagnetic resonance (EPR) spectra of lipids that are spin-labelled close to the terminal methyl end of the acyl chains are able to resolve the lipids directly contacting the protein from those in the fluid bilayer regions of the membrane. This allows determination of both the stoichiometry of lipid–protein interaction (i.e., number of lipid sites at the protein perimeter) and the selectivity of the protein for different lipid species (i.e., association constants relative to the background lipid). Spin-label EPR data are summarised for 20 or more different transmembrane peptides and proteins, and 7 distinct species of lipids. Lineshape simulations of the two-component conventional spin-label EPR spectra allow estimation of the rate at which protein-associated lipids exchange with those in the bulk fluid regions of the membrane. For lipids that do not display a selectivity for the protein, the intrinsic off-rates for exchange are in the region of 10 MHz: less than 10× slower than the rates of diffusive exchange in fluid lipid membranes. Lipids with an affinity for the protein, relative to the background lipid, have off-rates for leaving the protein that are correspondingly slower. Non-linear EPR, which depends on saturation of the spectrum at high radiation intensities, is optimally sensitive to dynamics on the timescale of spin-lattice relaxation, i.e., the microsecond regime. Both progressive saturation and saturation transfer EPR experiments provide definitive evidence that lipids at the protein interface are exchanging on this timescale. The sensitivity of non-linear EPR to low frequencies of spin exchange also allows the location of spin-labelled membrane protein residues relative to those of spin-labelled lipids, in double-labelling experiments. [ABSTRACT FROM AUTHOR]

Dried herbal samples consisting of root, rhizome, cortex, fruit, peel, flower, spike, ramulus, folium, and whole plant of 20 different medicinal herbs were investigated using pulsed photostimulated luminescence (PPSL), thermoluminescence (TL), and electron spin resonance spectroscopy (ESR) to identify γ-ray irradiation treatment. Samples were irradiated at 0–50 kGy using a 60Co irradiator. PPSL measurement was applied as a rapid screening method. Control samples of 19 different herbs had photon counts less than the lower threshold value (700 counts 60 s−1). The photon counts of non-irradiated clematidis radix and irradiated evodia and gardenia fruits were between the lower and upper threshold values (700–5,000 counts 60 s−1). TL ratios, i.e., integrated areas of the first glow (TL1)/the second glow (TL2), were found to be less than 0.1 in all non-irradiated samples and higher than 0.1 in irradiated ones providing definite proof of radiation treatment. ESR spectroscopy was applied as an alternative rapid method. In most of the irradiated samples, mainly radiation-induced cellulosic, sugar, and relatively complicated carbohydrate radical ESR signals were detected. No radiation-specific ESR signal, except one intense singlet, was observed for irradiated scrophularia and scutellaria root and artemisiae argyi folium. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Direct ESR and spin-trapping experiments were used to study the behavior of Nafion, a perfluorinated ionomer membrane used in fuel cells, when exposed in the laboratory to oxygen radicals produced by Fenton and photo-Fenton reactions. DMPO (5,5-dimethyl-1-pyroline) was used as the spin trap. The results suggest that the two ESR methods provide complementary information on Nafion fragmentation. The presence of membrane-derived fragments was suggested indirectly by the presence of a broad signal (line width ≈ 84 G) after prolonged exposure of the membrane to the Fenton reagent based on Ti(III), and by the DMPO adduct of a carbon-centered radical in the spin-trapping experiments. The most convincing proof for the presence of perfluorinated radicals was obtained in Nafion membranes partially neutralized by Cu(II), Fe(II) and Fe(III) upon exposure to UV-irradiation in the presence or absence of H2O2 (photo-Fenton treatment). Identification of the chain-end radical RCF2CF•2 with magnetic parameters different to those determined for the chainend detected in γ-irradiated Teflon, was taken as evidence for the attack of reactive oxygen radicals on the side-chain of the membrane. Additional support for this suggestion was the detection of the "quartet" ESR signal assigned to the CF3C•O radical, and of the "quintet" ESR signal assigned to the radical centered at the intersection of the main and side chains. The limitations and advantages of each approach are discussed. [ABSTRACT FROM AUTHOR]

There is growing evidence that reactive oxygen species (ROS) are involved in the muscular damage and soreness that is observed following strenuous or unaccustomed exercise. This study investigated the relationship between delayed onset muscle soreness (DOMS), muscle function and ROS following downhill running using electron spin resonance (ESR) spectroscopy and plasma malonaldehyde (MDA) concentrations. Eight physically active male subjects participated in two trials consisting of 30 min of running at ~65% VO2max on the flat (FLA) or a 15% downhill (DWN) gradient. Venous blood samples were drawn before, immediately after, and then 24, 48 and 72 h post exercise, and at the same time DOMS and muscle function were assessed. Blood was analysed for markers of ROS, total and differential white blood cell count, and creatine kinase. Muscle function was measured on an isokinetic dynamometer, whilst DOMS was assessed using a visual analogue scale. An increase in ROS, detected via ESR spectroscopy and MDA, was observed following DWN (P<0.05) but not following FLA. Increased DOMS and loss of muscle function were observed following DWN (P<0.05) but not following FLA (P>0.05). DWN resulted in a transient leukocytosis (P<0.05) occurring immediately post-exercise but returning to pre-exercise levels by 24 h. Although DWN resulted in an increase in ROS production, the increase occurred after the peak decline in muscle function and DOMS, suggesting that there may be a disassociation in the temporal relationship between ROS, loss of muscle function and DOMS. [ABSTRACT FROM AUTHOR]

Free radical reactions are believed to play an important role in the mechanism of Cr(VI)-induced carcinogenesis. Most studies concerning the role of free radical reactions have been limited to soluble Cr(VI). Various studies have shown that solubility is an important factor contributing to the carcinogenic potential of Cr(VI) compounds. Here, we report that reduction of insoluble PbCrO4 by glutathione reductase in the presence of NADPH as a cofactor generated hydroxyl radicals (•OH) and caused DNA damage. The •OH radicals were detected by electron spin resonance (ESR) using 5,5-dimethyl-N-oxide as a spin trap. Addition of catalase, a specific H2O2 scavenger, inhibited the •OH radical generation, indicating the involvement of H2O2 in the mechanism of Cr(VI)-induced •OH generation. Catalase reduced •OH radicals measured by electron spin resonance and reduced DNA strand breaks, indicating •OH radicals are involved in the damage measured. The H2O2 formation was measured by change in fluorescence of scopoletin in the presence of horseradish peroxidase. Molecular oxygen was used in the system as measured by oxygen consumption assay. Chelation of PbCrO4 impaired the generation of •OH radical. The results obtained from this study show that reduction of insoluble PbCrO4 by glutathione reductase/NADPH generates •OH radicals. The mechanism of •OH generation involves reduction of molecular oxygen to H2O2, which generates •OH radicals through a Fenton-like reaction. The •OH radicals generated by PbCrO4 caused DNA strand breakage. [ABSTRACT FROM AUTHOR]

The influence of cholesterol on the sphingomyelin (SM)/dioleoylphosphatidylcholine (DOPC) binary system was investigated in various respects. Electron spin resonance (ESR) measurements reveal that the order parameter of 5DS (5-doxyl stearic acid) in SM/DOPC bilayers increases notably when the concentration of cholesterol is over 30 mol%. Membrane potential measurements indicate that the K+ permeability of the SM/DOPC bilayer decreases steeply at 40 mol% cholesterol concentration. Both these experiments suggest that cholesterol reduces the motion amplitude of hydrocarbon chains abruptly above 30 mol%. In contrast to the ordering effects on the hydrocarbon chains, (31)P-NMR results indicate that cholesterol slightly increases the motion of phosphate groups of the lipids. (31)P-NMR also raises the possibility of domain formation in the presence of cholesterol. Fluorescence-quenching experiments verified that solid domains appear in the binary system when cholesterol is present, and percolation threshold occurs at 50 mol% cholesterol concentration. The solid domains bear the properties of liquid ordered phase, which is the basic structure of caveolae and functional rafts. So this work provides an artificial model for the study of rafts and caveolae on biological membranes. [ABSTRACT FROM AUTHOR]

Plasma-induced surface radicals formed on a variety of organic polymers have been studied by electron spin resonance (ESR), making it possible to provide a sound basis for future experimental design of polymer surface processing, i.e., plasma treatment. On the basis of the findings from such studies, several pharmaceutical applications in the field of drug engineering have been devised, which include preparation of double-compressed tablets for reservoir-type drug delivery system (DDS) of sustained- and delayed-release, and fabrication of functionalized composite powders applicable for matrix-type DDS by a mechanical application of plasma-irradiated polymer powder. [ABSTRACT FROM AUTHOR]

The stability of drugs incorporated in gelatin gels was studied, with a focus on the water mobility in the gels. Trichlormethiazide hydrolysis and kanamycin-catalyzed flomoxef hydrolysis in gelatin gels were chosen as models for apparent first-order and second-order hydrolysis, respectively. The mobility of water in gelatin gels was determined by NMR, ESR, and dielectric relaxation spectroscopies. The amount of bound water in the gels was determined from dielectric relaxation spectra. Spin-lattice relaxation time of water determined by O NMR and rotational correlation time of an ESR probe determined by an ESR probing method were useful in determining the micro viscosity of the gels. The hydrolysis rate of trichlormethi-azide in the gels was found to depend on the amount of free water available for the reaction, while that of flomoxef depended on the micro viscosity of the gels, which reflected the mobility of water molecules. Thus the dependence of hydrolysis rates on the water mobility was influenced by the hydrolysis mechanism. [ABSTRACT FROM AUTHOR]

The possible involvement of metal ions and free radicals in the cytotoxic mechanism of Adriamycin (ADR) was investigated, using a model system of Escherichia coli cells. It is shown that E. coli mediated the production of free radicals under anaerobic (ADR-semiquinone) and aerobic (superoxide) conditions. ADR-induced loss of colony-forming ability was enhanced by the addition of iron (Fe) chelates. These observations suggested that a Fenton-type free radical mechanism was responsible for ADR toxicity. However, the mortality rate was essentially unchanged by the exclusion of oxygen. It was also unaffected by the addition of H2O2, catalase, or chelating agents. Cu(II), Zn(II) or Mg(II) had no effect on ADR toxicity. ADR and iron chelates did not induce measurable amounts of DNA strand-breaks. These observations suggest a mechanism of ADR-induced cell killing that is enhanced by Fe chelates, but does not directly involve oxygen-derived free radicals. [ABSTRACT FROM AUTHOR]

The ESR and optical spectra of CuAlS: V has been studied by using crystal- and ligand-field theory. The energy Hamiltonian and ESR formulae for 3d electronic configurations at a tetragonal MX complex have been derived from the two spin-orbital coupling parameters model. The contribution from the spin-orbit coupling of the ligand to ESR and optical spectra has been considered in the calculations. The calculated results are in good agreement with the experimental findings and show that V ion substitutes for Cu-site. [ABSTRACT FROM AUTHOR]

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The results from this research indicate that canola meal (CM) can beused for adsorption of Zn2+, Cd2+, Cu2+, Pb2+ and Ni2+ from aqueous solutions. Theorder of sorption for these metals in single metal systems was as follows (molar basis): Zn2+ > Cu2+ > Cd2+ > Ni2+ > Pb2+. It was noted that a decreasein the concentration of CM caused a higher metal loading on the meal. Increases in the metal concentration, temperature or pH resulted inincreased sorption of the metals by the meal. The systems with identical ratios of CM to Zn2+ concentrations, regardless of their levels, resulted in the same amount of metal adsorbed per unit weight of meal. The Freundlich isotherm type model was used in this study and was found to fit the experimental equilibrium concentration data of Zn2+ and Cd2+; however, the Langmuir isotherm model fit only the equilibrium data of Zn2+. ScanningElectron Microscopy (SEM) and Energy-Dispersive X-ray (EDX) microanalyses revealed that the metal ions were sorbed mainly at the cell wall and only small amounts of ions diffused into the cytoplasm of the CM cells. The Electron Spin Resonance (ESR) tests were inconclusive regarding the direct participation of free radicals in copper sorption. [ABSTRACT FROM AUTHOR]