805 resultados para hot electron


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Individuals with systemic arterial hypertension have a higher risk of heat-related complications. Thus, the aim of this study was to examine the thermoregulatory responses of hypertensive subjects during recovery from moderate-intensity exercise performed in the heat. A total of eight essential hypertensive (H) and eight normotensive (N) male subjects (age=46.5±1.3 and 45.6±1.4 years, body mass index=25.8±0.8 and 25.6±0.6 kg/m2, mean arterial pressure=98.0±2.8 and 86.0±2.3 mmHg, respectively) rested for 30 min, performed 1 h of treadmill exercise at 50% of maximal oxygen consumption, and rested for 1 h after exercise in an environmental chamber at 38°C and 60% relative humidity. Skin and core temperatures were measured to calculate heat exchange parameters. Mean arterial pressure was higher in the hypertensive than in the normotensive subjects throughout the experiment (P<0.05, unpaired t-test). The hypertensive subjects stored less heat (H=-24.23±3.99 W·m−2vs N=-13.63±2.24 W·m−2, P=0.03, unpaired t-test), experienced greater variations in body temperature (H=-0.62±0.05°C vsN=-0.35±0.12°C, P=0.03, unpaired t-test), and had more evaporated sweat (H=-106.1±4.59 W·m−2vs N=-91.15±3.24 W·m−2, P=0.01, unpaired t-test) than the normotensive subjects during the period of recovery from exercise. In conclusion, essential hypertensive subjects showed greater sweat evaporation and increased heat dissipation and body cooling relative to normotensive subjects during recovery from moderate-intensity exercise performed in hot conditions.

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Cashew (Anacardium occidentale L.) apples from Pacajus, Ceará State, Brazil, were processed into high pulp content juice. The juice was packed either by hot fill or an aseptic process and evaluated for physical, physical-chemical, and sensorial changes during a 12-month storage period at room temperature. The results indicated that pH, soluble solids, total acidity, total sugar content and color did not change significantly during storage nor were affected by the type of filling. The sensorial analysis showed that juice acceptance remained high throughout the storage period regardless of the filling system. Differences in juice viscosity persisted between both processes.

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Este trabalho objetivou avaliar a estabilidade do suco tropical de acerola adoçado, elaborado pelos processos hot fill (garrafas de vidro) e asséptico (embalagens cartonadas), com relação às alterações químicas e físico-químicas (pH, sólidos solúveis totais, acidez total titulável, cor, açúcares redutores, não redutores e totais), sensoriais e microbiológicas, durante 350 dias de armazenamento em condições similares às de comercialização (28 °C ± 2 °C). Ao final do experimento, constatou-se que as amostras de suco de ambos os processos mantiveram uma adequada estabilidade microbiológica. O suco do processo hot fill teve maior aceitação global, enquanto o do processo asséptico manteve, ao final dos 350 dias, a aceitação inicial. As amostras do processo asséptico apresentaram inicialmente melhor sabor em comparação com as do processo hot fill, no entanto, as do processo hot fill mantiveram o sabor estável, enquanto o sabor do suco do processo asséptico teve menor aceitação ao longo do armazenamento. Ainda foram observadas, alterações químicas e físico-químicas nos sucos de ambos os processos. Em geral, o processo hot fill foi o mais eficiente em manter a estabilidade do suco.

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Chemical composition and nutritive value of hot pepper seeds (Capsicum annuum) grown in Northeast Region of China were investigated. The proximate analysis showed that moisture, ash, crude fat, crude protein and total dietary fiber contents were 4.48, 4.94, 23.65, 21.29 and 38.76 g/100 g, respectively. The main amino acids were glutamic acid and aspartic acid (above 2 g/100 g), followed by histidine, phenylalanine, lysine, arginine, cysteine, leucine, tryptophan, serine, glycine, methionine, threonine and tyrosine (0.8-2 g/100 g). The contents of proline, alanine, valine and isoleucine were less than 0.8 g/100 g. The fatty acid profile showed that linoleic acid, palmitic acid, oleic acid, stearic acid and linolenic acid (above 0.55 g/100 g) as the most abundant fatty acids followed lauric acid, arachidic acid, gondoic acid and behenic acid (0.03-0.15 g/100 g). Analyses of mineral content indicated that the most abundant mineral was potassium, followed by magnesium, calcium, iron, zinc, sodium and manganese. The nutritional composition of hot pepper seeds suggested that they could be regarded as good sources of food ingredients and as new sources of edible oils.

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Aims: The aim of this work was to assess the ultrastructural changes, cellular proliferation, and the biofilm formation ability of F. nucleatum as defense mechanisms against the effect of HNP-1. Materials and methods: The type strain of F. nucleatum (ssp. nucleatum ATCC 25586) and two clinical strains (ssp. polymorphum AHN 9910 and ssp. nucleatum AHN 9508) were cultured and incubated with four different test concentrations of recombinant HNP-1 (1, 5, 10 and 20 µg/ml) and one control group (0 µg/ml). Bacterial pellets from each concentration were processed for TEM imaging. Planktonic growth was assessed and colony forming units (CFU) were measured to determine the cellular proliferation. Scrambled HNP-1 was used for confirmation. Results: TEM analyses revealed a decrease in the outer membrane surface corrugations and roughness of the strain AHN 9508 with increasing HNP-1 concentrations. In higher concentrations of HNP-1, the strain AHN 9910 showed thicker outer membranes with a number of associated rough vesicles attached to the outer surface. For ATCC 25586, the treated bacterial cells contained higher numbers of intracellular granules with increasing the peptide concentration. Planktonic growth of the two clinical strains were significantly enhanced (P<0.001) with gradually increased concentrations of HNP-1. None of the planktonic growth results of the 3 strains incubated with the scrambled HNP-1 was statistically significant. HNP-1 decreased the biofilm formation of the two clinical strains, AHN 9910 and 9508, significantly (P<0.01 and P<0.001; respectively). Conclusions: The present in vitro study demonstrates that F. nucleatum has the ability to withstand the lethal effects of HNP-1 even at concentrations simulating the diseased periodontium in vivo. The increase in planktonic growth could act as defense mechanisms of F. nucleatum against HNP-1.

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Människor utnyttjar ofta kemi mångsidigt i sitt vardagliga liv utan att närmare tänka på detaljerna. Nuförtiden kan man framställa en ökande mängd av produkter ur förnybara råmaterial och en av de mest mångsidiga nybara råmaterialet i Norden är barrträd. Den lyriska lägerelden eller spiselden och möbler av ved samt papper är en väsentlig del av vardagen. Också livsmedel och läkemedel kan innehålla föreningar ur ved. Ved som råmaterial består av tre huvudkomponenten: cellulosa, som är uppbyggd av druvsockermolekyler är en långkedjad, oförgrenad polymer; lignin, som sammanhåller fibrerna i vedmaterialet som lim samt hemicellulosor, som ofta är uppbyggda av olika sockerarter och är en förgrenad polymer. Följaktligen består vedmaterialet av 70 % socker. I detta arbete har vi koncentrerat på i hemicellulosa och dess extraktion ur gran, samt bestämning av hemicellulosans egenskaper. Den slutliga målsättningen i forskningen var att skapa nya produkter ur gran. Forskning i extraktionens hemligheter eller hur hemicellulosa kan effektivt extraheras i den önskade formen kräver nya typers experimentellasanläggningar och experiment samt matematisk modellering. Den långkedjade hemicellulosan är lämplig för att användas t.ex. i skyddshinnor eller i livsmedel. Medel- och småmolekylär hemicellulosa kan användas som utgångsämne för framställning av bränslen, smörjmedel, sockersyror och alkoholer, av vilka xylitol är mest känd för alla pga hälsobefrämjande effekter. Det är utomordentligt viktigt ur miljöns och energiekonomins synvinkel att sträva efter effektivering av utnyttjandet av den värdefullaste och största naturtillgången, skogen i vårt land, med alla möjliga sätt. Resultaten av denna forskning utnyttjar avsevärt den växande, nya, på skogen baserande biobaseradeindustrin, som framställer nya spetsprodukter samt skapar nya arbetsplatser. ----------------------------------------------------- Ihmiset hyödyntävät usein huomaamattaan kemiaa monipuolisesti jokapäiväisessä elämässä. Nykyään kasvava määrä tuotteista kyetään valmistamaan uusiutuvista raaka-aineista ja yksi monipuolisimmista uusiutuvista luonnonvaroistamme pohjolassa ovat havupuut. Tunnelmallinen nuotio tai takkatuli ja puiset huonekalut sekä paperi ovat olennainen osa arkea. Myös elintarvikkeet ja lääkkeet voivat sisältää puusta peräisin olevia yhdisteitä. Puu materiaalina koostuu rakenteeltaan pääosin kolmesta osasta; selluloosasta, joka on rypälesokerista koostuva pitkäketjuinen haaroittumaton polymeeri, ligniinistä, joka toimii puun koossa pitävänä liima-aineena ja hemiselluloosasta, joka on useista eri sokereista rakentunut haaroittunut polymeeri. Näin ollen puusta 70 % on sokeria. Tässä työssä olemme keskittyneet hemiselluloosaan ja sen uuttamiseen kuusesta, sekä ominaisuuksien kartoittamiseen. Tutkimusaiheen lopullinen tavoite on luoda uusia tuotteita kuusesta. Uuton salojen tutkiminen eli miten hemiselluloosa saadaan tehokkaasti uutettua halutunlaisena vaatii uudenlaisia koelaitteistoja ja kokeita, sekä matemaattista mallintamista. Suurikokoinen hemiselluloosa on sopivaa käytettäväksi esimerkiksi suojakalvoissa tai elintarvikkeissa. Keskikokoista ja pienimolekyylistä hemiselluloosaa voidaan käyttää lähtöaineena valmistettaessa polttoaineita, voiteluaineita, sokerihappoja ja sokerialkoholeja, joista xylitoli on terveysvaikutustensa vuoksi kaikille tuttu. Niin ympäristömme kuin myös energiataloutemme kannalta on ensiarvoisen tärkeää pyrkiä kaikin keinoin tehostamaan maallemme arvokkaan, sekä luonnonvaroistamme yhden suurimman, metsän, vastuullista hyödyntämistä. Tämän tutkimuksen tulokset hyödyntävät merkittävästi maahamme nousevaa uutta metsään pohjautuvaa biojalostusteollisuutta, joka valmistaa uusia huipputuotteita sekä luo työpaikkoja.

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In oxygenic photosynthesis, the highly oxidizing reactions of water splitting produce reactive oxygen species (ROS) and other radicals that could damage the photosynthetic apparatus and affect cell viability. Under particular environmental conditions, more electrons are produced in water oxidation than can be harmlessly used by photochemical processes for the reduction of metabolic electron sinks. In these circumstances, the excess of electrons can be delivered, for instance, to O2, resulting in the production of ROS. To prevent detrimental reactions, a diversified assortment of photoprotection mechanisms has evolved in oxygenic photosynthetic organisms. In this thesis, I focus on the role of alternative electron transfer routes in photoprotection of the cyanobacterium Synechocystis sp. PCC 6803. Firstly, I discovered a novel subunit of the NDH-1 complex, NdhS, which is necessary for cyclic electron transfer around Photosystem I, and provides tolerance to high light intensities. Cyclic electron transfer is important in modulating the ATP/NADPH ratio under stressful environmental conditions. The NdhS subunit is conserved in many oxygenic phototrophs, such as cyanobacteria and higher plants. NdhS has been shown to link linear electron transfer to cyclic electron transfer by forming a bridge for electrons accumulating in the Ferredoxin pool to reach the NDH-1 complexes. Secondly, I thoroughly investigated the role of the entire flv4-2 operon in the photoprotection of Photosystem II under air level CO2 conditions and varying light intensities. The operon encodes three proteins: two flavodiiron proteins Flv2 and Flv4 and a small Sll0218 protein. Flv2 and Flv4 are involved in a novel electron transport pathway diverting electrons from the QB pocket of Photosystem II to electron acceptors, which still remain unknown. In my work, it is shown that the flv4-2 operon-encoded proteins safeguard Photosystem II activity by sequestering electrons and maintaining the oxidized state of the PQ pool. Further, Flv2/Flv4 was shown to boost Photosystem II activity by accelerating forward electron flow, triggered by an increased redox potential of QB. The Sll0218 protein was shown to be differentially regulated as compared to Flv2 and Flv4. Sll0218 appeared to be essential for Photosystem II accumulation and was assigned a stabilizing role for Photosystem II assembly/repair. It was also shown to be responsible for optimized light-harvesting. Thus, Sll0218 and Flv2/Flv4 cooperate to protect and enhance Photosystem II activity. Sll0218 ensures an increased number of active Photosystem II centers that efficiently capture light energy from antennae, whilst the Flv2/Flv4 heterodimer provides a higher electron sink availability, in turn, promoting a safer and enhanced activity of Photosystem II. This intertwined function was shown to result in lowered singlet oxygen production. The flv4-2 operon-encoded photoprotective mechanism disperses excess excitation pressure in a complimentary manner with the Orange Carotenoid Protein-mediated non-photochemical quenching. Bioinformatics analyses provided evidence for the loss of the flv4-2 operon in the genomes of cyanobacteria that have developed a stress inducible D1 form. However, the occurrence of various mechanisms, which dissipate excitation pressure at the acceptor side of Photosystem II was revealed in evolutionarily distant clades of organisms, i.e. cyanobacteria, algae and plants.

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Because of its high interest rates, Brazil attracts more and more speculative capital flows, called "hot money", under the form of foreign loans, direct or portfolio investments. Actually, the country is directly involved in a carry-trade strategy that tends to appreciate the real, what penalizes the Brazilian exportations of manufactured products. Moreover, capital inflows are extremely volatile, and their departure, causing a fall in loans granted to the Brazilian private banks, could provoke a dangerous burst of the speculative bubble they have contributed to form in the Brazilian real estate sector.

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The fragmentation patterns and mass spectra of some phenyl tin and -lead halide adducts with hexamethylphosphoramide are compared by subjecting them t~ electron impact and fast atom bombardment ionization in a mass spectrometer. This comparison is restricted to the metal-containing ions. Ligand-exchange mechanisms of some of the metal-containing species are explored by FAB-MS. Several moisturesensitive organo-metallics and H-bonded systems have been examined by FAB for attempted characterization, but without any success. Scavenging and trapping of water molecules by complex aggregates in solutions of quaternary ammonium fluorides and hydroxides are investigated by FAB to complement previous NMR-studies.

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The number of P700 (the reaction centre of Photosystem I) converted to P700+, in winter rye, was determined by measuring the absorbance change at 820nm . It was found, with a single turnover flash, that thylakoids isolated from cold grown plants have a 50% greater number of P700 oxidized than thylakoids isolated from warm grown plants. Incubation of thylakoids in the dark at 35 C did not change the number of P700 oxidized. The conversion of P700 to P700+ with a single flash can be compared to a steady state rate of electron transport using a Clark electrode. The results for P700 oxidation using the absorbance change at 820 nm measure effects within the PSI complex whereas the results obtained from a Clark electrode measures steady state electron transport between the cytochrome blf complex and the PSI complex. In contrast to the results for P700 oxidation it was shown, using a Clark electrode, that both thylakoids from cold grown plants and thylakoids incubated at in the dark 35 C exhibited 50% higher rates of electron transport than thylakoids from warm grown plants. The correlation between the higher rate of steady state PSI electron transport observed in thylakoids isolated from cold grown winter rye and number of active PSI reaction centres localizes the site of the increase to the PSI reaction centre. In contrast the lack of correlation after incubation at 35 C indicates the increase in the rate of light saturated electron transport in thylakoids isolated from cold grown plants and thylakoids incubated in the dark at 35 C occur by different mechanisms.

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Both El MS and FAB MS behavior of two groups of compounds, aryltin and ferrocene compounds, have been studied. For the aryltin compounds, the effect of substituent group position, substituent group type and ligand type on the El spectra have been explored in the El MS studies. The fragmentation mechanism has been investigated under El with linked scans, such as fragment ion scans(BJE), parent ion scans(B2JE) and constant neutral radical loss scans(B2(1-E)JE2). In the FAB MS studies, matrix optimization experiments have been carried out. The positive ion FAB MS studies focused on the effect of substituent group position, substituent group type and ligand type on the spectra. The fragmentation mechanisms of all the samples under positive ion FAB have been studied by means of the linked scans. The CA positive ion FAB fragmentation studies were also carried out for a typical sample. Negative ion FAB experiments of all the compounds have been done. And finally, the comparison of the El MS and FAB MS has been made. For ferrocenes, the studies concentrated on the fragmentation mechanism of each compound under El with linked scan techniques in the first field-free region and the applicability of positive/negative ion FAB MS to this group of compounds. The fragmentation mechanisms under positive ion FAB of those ferrocenes which can give positive ion FAB MS spectra were studied with the linked scan techniques. The CA +ve F AB fragmentation studies were carried out for a typical sample. Comparison of the E1 MS and FAB MS has been made.

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Linear alkylbenzenes, LAB, formed by the Alel3 or HF catalyzed alkylation of benzene are common raw materials for surfactant manufacture. Normally they are sulphonated using S03 or oleum to give the corresponding linear alkylbenzene sulphonates In >95 % yield. As concern has grown about the environmental impact of surfactants,' questions have been raised about the trace levels of unreacted raw materials, linear alkylbenzenes and minor impurities present in them. With the advent of modem analytical instruments and techniques, namely GCIMS, the opportunity has arisen to identify the exact nature of these impurities and to determine the actual levels of them present in the commercial linear ,alkylbenzenes. The object of the proposed study was to separate, identify and quantify major and minor components (1-10%) in commercial linear alkylbenzenes. The focus of this study was on the structure elucidation and determination of impurities and on the qualitative determination of them in all analyzed linear alkylbenzene samples. A gas chromatography/mass spectrometry, (GCIMS) study was performed o~ five samples from the same manufacturer (different production dates) and then it was followed by the analyses of ten commercial linear alkylbenzenes from four different suppliers. All the major components, namely linear alkylbenzene isomers, followed the same elution pattern with the 2-phenyl isomer eluting last. The individual isomers were identified by interpretation of their electron impact and chemical ionization mass spectra. The percent isomer distribution was found to be different from sample to sample. Average molecular weights were calculated using two methods, GC and GCIMS, and compared with the results reported on the Certificate of Analyses (C.O.A.) provided by the manufacturers of commercial linear alkylbenzenes. The GC results in most cases agreed with the reported values, whereas GC/MS results were significantly lower, between 0.41 and 3.29 amu. The minor components, impurities such as branched alkylbenzenes and dialkyltetralins eluted according to their molecular weights. Their fragmentation patterns were studied using electron impact ionization mode and their molecular weight ions confirmed by a 'soft ionization technique', chemical ionization. The level of impurities present i~ the analyzed commercial linear alkylbenzenes was expressed as the percent of the total sample weight, as well as, in mg/g. The percent of impurities was observed to vary between 4.5 % and 16.8 % with the highest being in sample "I". Quantitation (mg/g) of impurities such as branched alkylbenzenes and dialkyltetralins was done using cis/trans-l,4,6,7-tetramethyltetralin as an internal standard. Samples were analyzed using .GC/MS system operating under full scan and single ion monitoring data acquisition modes. The latter data acquisition mode, which offers higher sensitivity, was used to analyze all samples under investigation for presence of linear dialkyltetralins. Dialkyltetralins were reported quantitatively, whereas branched alkylbenzenes were reported semi-qualitatively. The GC/MS method that was developed during the course of this study allowed identification of some other trace impurities present in commercial LABs. Compounds such as non-linear dialkyltetralins, dialkylindanes, diphenylalkanes and alkylnaphthalenes were identified but their detailed structure elucidation and the quantitation was beyond the scope of this study. However, further investigation of these compounds will be the subject of a future study.

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Light microscope studies of the mycoparasite Piptocephalis virginiana revealed that the cylindrical spores of the parasite became spherical upon germination and produced 1-4 germ tubes. Generally t"l.vO germ tubes were produced by each spore. When this parasite was inoculated on its potential hosts, Choanephora cucurbitarum and Phascolomyces articulosus, the germ tube nearest to the host hypha continued to grow and made contact with the host hypha. The tip of the parasite's germ tube became swollen to form a distinct appressorium. Up to this stage the behavior of the parasite was similar regardless of the nature of the host. In the compatible host-parasite combination, the parasite penetrated the host, established a nutritional relationship and continued to grow to cover the host completely with its buff colored spores in 3-4 days. In the incompatible host-parasite combination, the parasite penetrated the host but its further advance was arrested. As a result of failure to establish a nutritional relationship with the resistant host, the parasite made further attempts to penetrate the host at different sites producing multiple infections. In the absence of nutrition the parasite weakened and the host outgrew the parasite completely. In the presence of a non-host species, Linderina pennispora the parasite continued to grow across the non-host 1).yp_hae vlithout establishing an initial contact. Germination studies showed that the parasite germinated equally well in the presence of host and non-host species. Further electron microscope studies revealed that the host-parasite interaction between P. virginiana and its host, C. cucurbi tarum, was compatible when the host hyphae were young slender, with a thin cell wall of one layer. The parasite appeared to penetrate mechanically by pushing the host-cell wall inward. The host plasma membrane invaginated along the involuted cell wall. The older hyphae of C. cucurbitarum possessed two distinct layers of cell wall and-showed an incompatible interaction when challenged vlith the parasite. At the point of contact, the outer layer of the host-cell wall dissolved, probably by enzymatic digestion, and the inner layer became thickened and developed a papilla as a result of its response to the parasite. The haustoria of the parasite in the old hyphae were always surrounded by a thick, well developed sheath, whereas the haustoria of the same age in the young host mycelium were devoid of a sheath during early stages of infection. Instead, they were in direct contact with the host protoplast. The incompatible interaction between a resistant host, P. articulosus and the parasite showed similar results as with the old hyphae of C. cucurbitarum. The cell wall of P. articulosus appeared thick-with two or more layers even in the 18-22 h-old hyphae. No contact or interaction was established between the parasite and the non-host L. pennispora. The role of cell wall in the resistance mechanism is discussed.

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There is considerable interest in intramolecular energy transfer, especially in complexes which absorb visible light, because it is crucial to the better understanding of photoharvesting systems in photosynthetic organisms and for utilizing solar energy as well. Porphyrin dimers represent one of the best systems for the exploration of light-induced intramolecular energy transfer. Many kinds of porphyrins and porphyrin dimers have been studied over the past decade, however little attention has been paid to the influence of paramagnetic metals on the behavior of their excited states. In this thesis, Electron Paramagnetic Resonance Spectroscopy (EPR) is used to study such compounds. After light irradiation, porphyrins easily produce a variety of excited states, which are spin polarized and can be detected by the time-resolved (TR) EPR technique. The spin polarized results for vanadyl porphyrins, their electrostatically-coupled dimers, a covalently-linked copper porphyrin-free base porphyrin dimer, and free base porphyrins are presented in this thesis. From these results we can conclude that the spin polarization patterns of vanadyl porphyrins come primarily from the trip-quartet state generated by intersystem crossing (lSC) from the excited sing-doublet state through the trip-doublet state. The spin polarization pattern of electrostatically-coupled vanadyl porphyrin-free base porphyrin dimer is produced by the triplet state of the free base porphyrin half which is coupled to the unpaired electron on the vanadyl ion.