Search

The purpose of this study was to analyze the response of different initial contamination levels of Alicyclobacillus acidoterrestrisATCC 49025 spores in apple juice as affected by pulsed light treatment (PL, batch mode, xenon lamp, 3pulses/s, 0–71.6J/cm2). Biphasic and Weibull frequency distribution models were used to characterize the relationship between inoculum size and treatment time with the reductions achieved after PL exposure. Additionally, a second order polynomial model was computed to relate required PL processing time to inoculum size and requested log reductions. PL treatment caused up to 3.0–3.5 log reductions, depending on the initial inoculum size. Inactivation curves corresponding to PL-treated samples were adequately characterized by both Weibull and biphasic models (Radj294–96%), and revealed that lower initial inoculum sizes were associated with higher inactivation rates. According to the polynomial model, the predicted time for PL treatment increased exponentially with inoculum size.

La incursión del instrumentador quirúrgico profesional como líder en los procesos de asepsia y antisepsia en diferentes contextos socioculturales como los tatuadores y modificadores corporales, se fundamenta en la enseñanza y aprendizaje virtual basada en las TIC y el OVA.

Poly(ADP-ribose) polymerase-1 (PARP-1) is a nuclear enzyme that plays a critical role in diverse cellular functions, such as DNA damage detection and repair, transcriptional regulation and cell death. Furthermore, PARP-1 has emerged as a key player in the pathogenesis of multiple inflammatory diseases and has become a promising target for the treatment of cardiovascular disorders, neurodegenerative diseases and cancer. An increasing body of evidence has linked alterations in the expression levels of PARP-1, enzymatic activity and presence of polymorphism to gastrointestinal malignancies, including oesophageal, gastric, pancreas, liver and colorectal cancers. PARP inhibition has been proposed as a valuable strategy for treating these gastrointestinal disorders. This paper summarises the most significant current literature on the involvement of PARP-1 in gastrointestinal cancer, focusing in particular on its role in the development and occurrence of tumours, providing information about clinical trials and exploring therapeutic possibilities.

The oxygen reduction reaction (ORR) on the cathode of a polymer electrolyte fuel cell requires the use of a catalyst based on Pt, one of the most expensive metals on the earth. A number of strategies, including optimization of shape or facet, formation of alloys with other metals, and incorporation of a different metal into the core, have been investigated to enhance the activity of a Pt-based catalyst and thus reduce the loading of Pt. This article reports the synthesis and characterization of Pd@Pt–Ni core–shell octahedra with high activity toward ORR. The octahedra with an edge length of 8 nm were obtained by directly depositing thin, conformal shells of a Pt–Ni alloy on Pd octahedra of 6 nm in edge length. The key to the success of this synthesis is the use of an amphiphilicsolvent to ensure good compatibility between the solvents typically used for the syntheses of Pd and Pt–Ni nanocrystals. The core–shell structure was confirmed by a number of techniques, including scanning transmission electron microscopy, energy-dispersive X-ray spectroscopy mapping, in situX-ray diffraction under H2and He, and electrochemical measurements. Relative to the state-of-the-art Pt/C catalyst, the Pd@Pt–Ni/C catalyst showed mass and specific ORR activities enhanced by 12.5- and 14-fold, respectively. The formation of a core–shell structure helped increase the electroactive surface area in terms of Pt and thus the mass activity. During an accelerated durability test, the mass activity of the Pd@Pt–Ni/C catalyst only dropped by 1.7% after 10 000 cycles.

The presence of Listeria monocytogenescould seriously affect the safety of nonpasteurized fruit juices. High-intensity ultrasound combined with mild heat treatment and natural antimicrobials may be an alternative technology for fruit juice preservation. The response of L. monocytogenesin orange juice to combined treatments involving moderate temperature (45°C), high-intensity ultrasound (600 W, 20 kHz, 95.2-μm wave amplitude), and the addition of different levels of vanillin (0, 1,000, 1,500, and 2,000 ppm), citral (0, 75, and 100 ppm), or both was investigated to find the most effective inactivation treatment. Nonlinear semilogarithmic survival curves were successfully fitted by the Weibull model. The presence of vanillin or citral greatly increased the bactericidal effect of thermosonication and changed the distribution of inactivation times. When both antimicrobials were added together and ultrasound was applied, narrowest frequency shapes, skewed to the right, with low variances and death time means between 1.6 and 2.6 min, were obtained. Orange juices with 1,500 or 1,000 ppm of vanillin and 100 ppm of citral were pleasant for the consumers.

We describe the gonadal and abdominal fat storage cycles for a population of Caiman crocodilus fuscuskept in captivity at a breeding farm. The reproductive cycles of males and females are clearly seasonal. Vitellogenic follicles were observed in females year‐round; however, the follicular growth that produces the preovulatory follicles for the breeding season occurs in November–May (most of the dry season to the beginning of the rainy season). These months correspond with the presence of physiologically reproductive males. Oviposition takes place during the wet season (April–August) and the births occur at the end of this season (September–November). Fat storage was not related to reproductive activity, and did not vary by month or between sexes. Although environmental and hormonal conditions have been improved for these captive animals, they maintain a strongly seasonal reproductive cycle, historically fixed to oviposit in the most favorable period for nest construction and hatching during the rainy season. Zoo Biol 22:121–133, 2003. © 2003 Wiley‐Liss, Inc.

A combined factors preservation technology involving blanching and vacuum solutes (sucrose, potassium sorbate, ascorbic and citric acids, zinc chloride) impregnation was proposed to minimize color changes in minimally processed kiwifruit slices during one month storage. Atmospheric impregnation was also studied in order to compare both impregnation techniques. A Box‐Behnken design was adopted and second order polynomial models were computed for different storage times to relate some process variables (blanching time, zinc content, storage temperature) to a color function (Brown Index). As the storage time increased, the response surfaces for vacuum treated fruits were vertically displaced to greater Brown Index values while the response surface behavior for atmospheric impregnated fruits were less dependent on storage time. For vacuum treated fruits, combinations of blanching and addition of zinc chloride improved the color of the finished product at all storage temperatures assayed, but these treatments were detrimental for atmospheric impregnated fruits, increasing significantly the Brown Index values. After storage, total chlorophyll had been degraded between 70 and 90% depending on the pretreatments. There did not appear to be any consistent relation between the changes which occurred in the total chlorophyll content and color.

The analysis of the vcobands in the I. R. spectrum of p-substituted α-phenylthioacetones indicates a cis/gauche rotational isomerism. The slight solvent effect on the αc/αg ratios on going from a non polar solvent to a polar one, for the title compounds, as well as the minute sensitivity of the vco (cis) frequencies on going from electron-attracting to electron-donating substituents are interpreted on the grounds of the Field (F) and Inductive (I) Effects, which act in opposition in the cis rotamer, practically cancelling each other. The decreasing cis/gauche population ratio on going from electron-attracting to electron-donating substituents suggests the Occurrence of the hyperconjugative interaction in the gauche rotamers of the title compounds. The progressive shielding effect on the methylene and carbonyl carbon atoms in the 13C NMR spectra, on going from electron-donating to electron-attracting substituents is ascribed at least in part, to the "Reserve Polar Effect".

The carbonyl stretching frequencies and the apparent molar absorptivities are reported for some α-(alkylthio)-thioacetates, thiopropionate and thioisobutyrate, in the fundamental and in the first overtone regions and compared to those for the corresponding unsubstituted thioesters. In the α-(alkylthio)-thioacetate series the data indicate the presence of two rotamers: cis and gauche. The unusual solvent effect and δ νCO shifts for the cis conformers as compared to other α-hetero-substituted carbonyl compounds are interpreted in terms of a decrease in polarity in relation to the gauche conformers. The larger negative δνCO values for the gauche conformers, which are still more increased by the increased bulkiness of the α-alkylthio group in comparison with the other α-sulfur substituted carbonyl compounds, are attributed to the gauche repulsion between two alkylthio-groups. The presence of two gauche rotamers in the α-(ethylthio)-thiopropionate and one in the α-(ethylthio)-thioisobutyrate is observed and the δνCO values discussed in terms of change in the mechanical coupling and carbonyl angle. Charge transfer from πCO to 3d(S) and hyperconjugative σC-S/πCO interaction are invoked to explain the obtained results.

The analysis of the vco bands in the IR spectra of the 3-(2'-chlorocyclopentylthio)- and 3-(2'-chloro-1'-methylpropen-1'-ylthio)-thiochromones and their 3-sulfinyl and 3-sulfonyl derivatives, supported by molecular mechanics calculations of 3-methylthio, 3-methylsulfinyl- and 3-methylsulfonyl-thiochromones, taken as model compounds, indicates the existence of a single conformer for the whole series except for the case of the 3-(2'-chloro-1'-methylpropen-1'-ylsulfinyl)-thiochromone where three conformers can be observed. The negative carbonyl frequency shifts (Δv) for the 3-sulfinyl- and 3-thio-thiochromone derivatives and the positive carbonyl shifts for the 3-sulfonyl-thiochromone derivatives are interpreted on the grounds of an interplay of the πco → 3dSOn orbital interaction with the inductive and field effects of the 3-substituents. The orbital interaction is responsible for the shorter S…O intramolecular contact observed previously from X-ray data of some 3-thio-thiochromone derivatives. The bathochromically shifted n π →CO* band for the 3-thio- and 3-sulfinyl-thiochromone derivatives and the slight hypsochromic effect for the 3-sulfonyl-thiochromone derivatives are discussed in terms of the relative energy level stabilization of the πCO* orbital (due to the πco*/3dSOn orbital interaction) and the no(co) lone pair (due to the electron-attracting inductive effect of the 3-sulfur-substituent). The IR and UV spectra of thiochroman-4-one show the existence of a mixture of two conformers, the twist-boat being the one where the transannular interaction between the 3p(s) π →co* orbitals takes place.

The analysis of the carbonyl (ΔνCO) and carbon-carbon double bond (ΔνC=C) frequency shifts for some 3-thio-substituted thiochromones and their 3-sulfinyl- and 3-sulfonyl derivatives indicated the occurrence of both πCO/3dSOn and nO(CO)/σ*C-SOn orbital interactions in the ground state of the title compounds.

The analysis of the carbonyl (ΔνCo) and carbon-carbon double bond (ΔνC=C) frequency shifts for some 3-thio-substituted thiochromones and their 3-sulfinyl- and 3-sulfonyl derivatives indicated the occurrence of both πCO/3dSOn and nO(CO)/σ*C-SOn orbital interactions in the ground state of the title compounds.

The analysis of the vco bands in the I.R. spectra of ω-(p-phenylthio)-p-substituted acetophenones indicates the presence of cislgauche rotational isomerism. The decreasing cislgauche ratio on going from electron-attracting to electron-donating substituents at the phenylthio group in each p-substituted ace-tophenone series is discussed in terms of the π*co/σc-s hyperconjugative interaction in the gauche rotamers. The carbonyl cis shifts (δvc) of the title compounds are interpreted as due to an interplay of Field (F) and Inductive (I) Effects. The carbonyl gauche shifts (δvs) trend in the whole series has been ascribed to the variation of the extension of the π*co/σc-s hyperconjugative interaction. The lower Non-Additivity Effect (NAE) of the methylene carbon of the title compounds in relation to the corresponding (ω-bromo and ω-iodo acetophenones together with the lowest NAE of the methylene carbon for the (ω-(p-nitrophenylthio)-p-nitroacetophenone (3) suggests the simultaneous occurrence of the π*co/σc-s and π*co/σc-s orbital interactions. The U.V. spectra of the ω-thiosubstituted acetophenones display a n→ π*co band which is bathochromically shifted in relation to the corresponding acetophenones except for compound (3) where this band is hypsochromically shifted. This behavior has been ascribed mainly to the π*co/σc·s hyperconjugative interaction in the excited state.

The carbonyl stretching frequencies and the apparent molar absorptivities are reported for some ω-ethylthio-p-substituted acetophenones and for the corresponding unsubstituted acetophenones. In the ω-ethylthio-series the solvent effect indicates the presence of the cis/gauche rotational isomerism, being the gauche rotamer predominant in the whole series (ca. 90%). In the ω-ethylthioacetophenones, on going from electron-attracting to electron-donating substituents, the progressive increase in the carbonyl cis shifts (Δνc) is attributed to the increasing Field Effect between C=O and C-S dipoles, and the progressive decrease in the carbonyl gauche shifts (Δνg) is due to the deacreasing contribution of the hyperconjugative interaction between πCO and σc-s orbitals. The U.V. spectra of the ω-ethylthioacetophenones display a n → π*CO band which is bathochromically shifted in relation to the corresponding acetophenones, indicating the occurrence of the hyperconjugative interaction between π*CO and σ*c-s orbitals in the excited state. 13C NMR data for the methylene group of ω-ethylthioacetophenones, compared to those for some ω-haloacetophenones,2,3 suggest that in the fundamental state besides the hyperconjugative interaction, there is also the occurrence of charge transfer from πCO to 3d(S) orbitals.