Transverse pseudo-nonlinear effects measured in solid-state laser materials using a sensitive time-resolved technique

We present a detailed study of the Baryscan technique, a new efficient alternative to the widespread Z-scan technique which has been demonstrated [Opt. Lett. 36:8, 2011] to reach among the highest sensitivity levels. This method is based upon the measurement of optical nonlinearities by means of beam centroid displacements with a position sensitive detector and is able to deal with any kind of lensing effect. This technique is applied here to measure pump-induced electronic refractive index changes (population lens), which can be discriminated from parasitic thermal effects by using a time-resolved Baryscan experiment. This method is validated by evaluating the polarizability variation at the origin of the population lens observed in the reference Cr3+:GSGG laser material.

Production of a xylose-stimulated beta-glucosidase and a cellulase-free thermostable xylanase by the thermophilic fungus Humicola brevis var. thermoidea under solid state fermentation

Humicola brevis var. thermoidea cultivated under solid state fermentation in wheat bran and water (1:2 w/v) was a good producer of beta-glucosidase and xylanase. After optimization using response surface methodology the level of xylanase reached 5,791.2 +/- A 411.2 U g(-1), while beta-glucosidase production was increased about 2.6-fold, reaching 20.7 +/- A 1.5 U g(-1). Cellulase levels were negligible. Biochemical characterization of H. brevis beta-glucosidase and xylanase activities showed that they were stable in a wide pH range. Optimum pH for beta-glucosidase and xylanase activities were 5.0 and 5.5, respectively, but the xylanase showed 80 % of maximal activity when assayed at pH 8.0. Both enzymes presented high thermal stability. The beta-glucosidase maintained about 95 % of its activity after 26 h in water at 55 A degrees C, with half-lives of 15.7 h at 60 A degrees C and 5.1 h at 65 A degrees C. The presence of xylose during heat treatment at 65 A degrees C protected beta-glucosidase against thermal inactivation. Xylanase maintained about 80 % of its activity after 200 h in water at 60 A degrees C. Xylose stimulated beta-glucosidase activity up to 1.7-fold, at 200 mmol L-1. The notable features of both xylanase and beta-glucosidase suggest that H. brevis crude culture extract may be useful to compose efficient enzymatic cocktails for lignocellulosic materials treatment or paper pulp biobleaching.

ScPdZn and ScPtZn with YAlGe type structure: group-subgroup relation and 45Sc solid state NMR spectroscopy

The intermetallic compounds ScPdZn and ScPtZn were prepared from the elements by high-frequency melting in sealed tantalum ampoules. Both structures were refined from single crystal X-ray diffractometer data: YAlGe type, Cmcm, a = 429.53(8), b = 907.7(1), c = 527.86(1) pm, wR2 = 0.0375, 231 F2 values, for ScPdZn and a = 425.3(1), b = 918.4(2), c = 523.3(1) pm, wR2 = 0.0399, 213 F2 values for ScPtZn with 14 variables per refinement. The structures are orthorhombically distorted variants of the AlB2 type. The scandium and palladium (platinum atoms) build up ordered networks Sc3Pd3 and Sc3Pt3 (boron networks) which are slightly shifted with respect to each other. These networks are penetrated by chains of zinc atoms (262 pm in ScPtZn) which correspond to the aluminum positions, i.e. Zn(ScPd) and Zn(ScPt). The corresponding group-subgroup scheme and the differences in chemical bonding with respect to other AlB2-derived REPdZn and REPtZn compounds are discussed. 45Sc solid state NMR spectra confirm the single crystallographic scandium sites. From electronic band structure calculations the two compounds are found metallic with free electron like behavior at the Fermi level. A larger cohesive energy for ScPtZn suggests a more strongly bonded intermetallic than ScPdZn. Electron localization and overlap population analyses identify the largest bonding for scandium with the transition metal (Pd, Pt).

Thermostable invertases from Paecylomyces variotii produced under submerged and solid-state fermentation using agroindustrial residues

The filamentous fungus Paecylomices variotii was able to produce high levels of cell extract and extracellular invertases when grown under submerged fermentation (SbmF) and solid-state fermentation, using agroindustrial products or residues as substrates, mainly soy bran and wheat bran, at 40A degrees C for 72 h and 96 h, respectively. Addition of glucose or fructose (a parts per thousand yen1%; w/v) in SbmF inhibited enzyme production, while the addition of 1% (w/v) peptone as organic nitrogen source enhanced the production by 3.7-fold. However, 1% (w/v) (NH4)(2)HPO4 inhibited enzyme production around 80%. The extracellular form was purified until electrophoretic homogeneity (10.5-fold with 33% recovery) by DEAE-Fractogel and Sephacryl S-200 chromatography. The enzyme is a monomer with molecular mass of 102 kDa estimated by SDS-PAGE with carbohydrate content of 53.6%. Optima of temperature and pH for both, extracellular and cell extract invertases, were 60A degrees C and 4.0-4.5, respectively. Both invertases were stable for 1 h at 60A degrees C with half-lives of 10 min at 70A degrees C. Mg2+, Ba2+ and Mn2+ activated both extracellular and cell extract invertases from P. variotii. The kinetic parameters K-m and V-max for the purified extracellular enzyme corresponded to 2.5 mM and 481 U/mg prot(-1), respectively.

Incorporation of PbF2 into Heavy Metal Oxide Borate Glasses. Structural Studies by Solid State NMR

A series of heavy metal oxide (HMO) glasses with composition 26.66B(2)O(3)-16GeO(2)-4 Bi2O3-(53.33-x)PbO-xPbF2 (0 <= x <= 40) were prepared and characterized with respect to their bulk (glass transition and crystallization temperatures, densities, molar volumes) and spectroscopic properties. Homogeneous glasses are formed up to x = 30, while crystallization of beta-PbF2 takes place at higher contents. Substitution of PbO by PbF2 shifts the optical band gap toward higher energies, thereby extending the UV transmission window significantly toward higher frequencies. Raman and infrared absorption spectra can be interpreted in conjunction with published reference data. Using B-11 and F-19 high-resolution solid state NMR as well as B-11/F-19 double resonance methodologies, we develop a quantitative structural description of this material. The fraction of four-coordinate boron is found to be moderately higher compared to that in glasses with the same PbO/B2O3 ratios, suggesting some participation of PbF2 in the network transformation process. This suggestion is confirmed by the F-19 NMR spectra. While the majority of the fluoride ions is present as ionic fluoride, similar to 20% of the fluorine inventory acts as a network modifier, resulting in the formation of four-coordinate BO3/2F- units. These units can be identified by F-19{B-11} rotational echo double resonance and B-11{F-19} cross-polarization magic angle spinning (CPMAS) data. These results provide the first unambiguous evidence of B-F bonding in a PbF2-modified glass system. The majority of the fluoride ions are found in a lead-dominated environment. F-19-F-19 homonuclear dipolar second moments measured by spin echo decay spectroscopy are quantitatively consistent with a model in which these ions are randomly distributed within the network modifier subdomain consisting of PbO, Bi2O3, and PbF2. This model, which implies both the features of atomic scale mixing with the network former borate species and some degree of fluoride ion clustering is consistent with all of the experimental data obtained on these glasses.

Preliminary Characterization of Novel Extra-cellular Lipase from Penicillium crustosum Under Solid-State Fermentation and its Potential Application for Triglycerides Hydrolysis

Current studies about lipase production involve the use of agro-industrial residues and newly isolated microorganisms aimed at increasing economic attractiveness of the process. Based on these aspects, the main objective of this work is to perform the partial characterization of enzymatic extracts produced by a newly isolated Penicillium crustosum in solid-state fermentation. Lipase extract presented optimal temperature and pH of 37 A degrees C and 9-10, respectively. The concentrated enzymatic extract showed more stability at 25 A degrees C and pH 7. The enzymes kept 100% of their enzymatic activity until 60 days of storage at 4 and -10 A degrees C. The stability under calcium salts indicated that the hydrolytic activity presented decay with the increase of calcium concentration. The specificity under several substrates indicated good enzyme activities in triglycerides from C4 to C18.

Adding value to the Brazilian sisal: acid hydrolysis of its pulp seeking production of sugars and materials

The present work is inserted into the broad context of the upgrading of lignocellulosic fibers. Sisal was chosen in the present study because more than 50% of the world's sisal is cultivated in Brazil, it has a short life cycle and its fiber has a high cellulose content. Specifically, in the present study, the subject addressed was the hydrolysis of the sisal pulp, using sulfuric acid as the catalyst. To assess the influence of parameters such as the concentration of the sulfuric acid and the temperature during this process, the pulp was hydrolyzed with various concentrations of sulfuric acid (30-50%) at 70 A degrees C and with 30% acid (v/v) at various temperatures (60-100 A degrees C). During hydrolysis, aliquots were withdrawn from the reaction media, and the solid (non-hydrolyzed pulp) was separated from the liquid (liquor) by filtering each aliquot. The sugar composition of the liquor was analyzed by HPLC, and the non-hydrolyzed pulps were characterized by viscometry (average molar mass), and X-ray diffraction (crystallinity). The results support the following conclusions: acid hydrolysis using 30% H2SO4 at 100 A degrees C can produce sisal microcrystalline cellulose and the conditions that led to the largest glucose yield and lowest decomposition rate were 50% H2SO4 at 70 A degrees C. In summary, the study of sisal pulp hydrolysis using concentrated acid showed that certain conditions are suitable for high recovery of xylose and good yield of glucose. Moreover, the unreacted cellulose can be targeted for different applications in bio-based materials. A kinetic study based on the glucose yield was performed for all reaction conditions using the kinetic model proposed by Saeman. The results showed that the model adjusted to all 30-35% H2SO4 reactions but not to greater concentrations of sulfuric acid. The present study is part of an ongoing research program, and the results reported here will be used as a comparison against the results obtained when using treated sisal pulp as the starting material.

Molecular dynamics of poly(Ethylene Glycol) intercalated in clay, studied using 13C solid-state NMR

In this study, Cross-Polarization Magic-angle Spinning CP/MAS, 2D Exchange, Centerband-Only Detection of Exchange (CODEX), and Separated-Local-Field (SLF) NMR experiments were used to study the molecular dynamics of poly(ethylene glycol) (PEG) inside Hectorite/PEG intercalation compounds in both single- and double-layer configurations. The results revealed that the overall amplitude of the motions of the PEG chain in the single-layer configuration is considerably smaller than that observed for the double-layer intercalation compound. This result indicates that the effect of having the polymer chain interacting with both clay platelets is to produce a substantial decrease in the motional amplitudes of those chains. The presence of these dynamically restricted segments might be explained by the presence of anchoring points between the clay platelets and the PEG oxygen atoms, which was induced by the Na+ cations. By comparing the PEG motional amplitudes of the double-layered nanocomposites composed of polymers with different molecular weights, a decrease in the motional amplitude for the smaller PEG chain was observed, which might also be understood using the presence of anchoring points.

Bose-Einstein Condensation of Magnons in NiCl2-4SC(NH2)(2)

A Bose-Einstein condensation (BEC) has been observed in magnetic insulators in the last decade. The condensed bosons are magnons associated with an ordered magnetic phase induced by a magnetic field. We review the experiments in the spin-gap compound NiCl2-4SC(NH2)(2), in which the formation of BEC occurs by applying a magnetic field at low temperatures. This is a contribution to the celebration of the 50th anniversary of the Solid State and Low Temperature Laboratory of the University of So Paulo, where this compound was first magnetically characterized.

GROUND STATE AND NON-GROUND STATE SOLUTIONS OF SOME STRONGLY COUPLED ELLIPTIC SYSTEMS

We study an elliptic system of the form Lu = vertical bar v vertical bar(p-1) v and Lv = vertical bar u vertical bar(q-1) u in Omega with homogeneous Dirichlet boundary condition, where Lu := -Delta u in the case of a bounded domain and Lu := -Delta u + u in the cases of an exterior domain or the whole space R-N. We analyze the existence, uniqueness, sign and radial symmetry of ground state solutions and also look for sign changing solutions of the system. More general non-linearities are also considered.

Effect of the interaction between food state and the action of estrogen on oxytocinergic system activity

Increased plasma osmolality by food intake evokes augmentation of plasma oxytocin (OT). Ovarian steroids may also influence the balance of body fluids by acting on OT neurones. Our aim was to determine if estrogen influences the activity of OT neurones in paraventricular nucleus (PVN) and supraoptic nucleus (SON) under different osmotic situations. Ovariectomized rats (OVX) were treated with either estradiol (E-2) or vehicle and were divided into three groups: group I was fed ad libitum, group II underwent 48 h of fasting, and group III was refed after 48 h of fasting. On the day of the experiment, blood samples were collected to determine the plasma osmolality and OT. The animals were subsequently perfused, and OT/FOS immunofluorescence analysis was conducted on neurones in the PVN and the SON. When compared to animals which were fasted or fed ad libitum, the plasma osmolality of refed animals was higher, regardless of whether they were treated with vehicle or E-2. We observed neural activation of OT cells in vehicle-or E-2-treated OVX rats refed after 48 h of fasting, but not in animals fed ad libitum or in animals that only underwent 48 h of fasting. Finally, the percentage of neurones that co-expressed OT and FOS was lower in both the PVN and the SON of animals treated with E-2 and refed, when compared to vehicle-treated animals. These results suggest that E-2 may have an inhibitory effect on OT neurones and may modulate the secretion of OT in response to the increase of osmolality induced by refeeding. Journal of Endocrinology (2012) 212, 129-138

Impact of the Manaus urban plume on trace gas mixing ratios near the surface in the Amazon Basin: Implications for the NO-NO2-O-3 photostationary state and peroxy radical levels

We measured the mixing ratios of NO, NO2, O-3, and volatile organic carbon as well as the aerosol light-scattering coefficient on a boat platform cruising on rivers downwind of the city of Manaus (Amazonas State, Brazil) in July 2001 (Large-Scale Biosphere-Atmosphere Experiment in Amazonia-Cooperative LBA Airborne Regional Experiment-2001). The dispersion and impact of the Manaus plume was investigated by a combined analysis of ground-based (boat platform) and airborne trace gas and aerosol measurements as well as by meteorological measurements complemented by dispersion calculations (Hybrid Single-Particle Lagrangian Integrated Trajectory model). For the cases with the least anthropogenic influence (including a location in a so far unexplored region similar to 150 km west of Manaus on the Rio Manacapuru), the aerosol scattering coefficient, sigma(s), was below 11 Mm(-1), NOx mixing ratios remained below 0.6 ppb, daytime O-3 mixing ratios were mostly below 20 ppb and maximal isoprene mixing ratios were about 3 ppb in the afternoon. The photostationary state (PSS) was not established for these cases, as indicated by values of the Leighton ratio, Phi, well above unity. Due to the influence of river breeze systems and other thermally driven mesoscale circulations, a change of the synoptic wind direction from east-northeast to south-southeast in the afternoon often caused a substantial increase of ss and trace gas mixing ratios (about threefold for sigma(s), fivefold for NOx, and twofold for O-3), which was associated with the arrival of the Manaus pollution plume at the boat location. The ratio F reached unity within its uncertainty range at NOx mixing ratios of about 3 ppb, indicating "steady-state" conditions in cases when radiation variations, dry deposition, emissions, and reactions mostly involving peroxy radicals (XO2) played a minor role. The median midday/afternoon XO2 mixing ratios estimated using the PSS method range from 90 to 120 parts per trillion (ppt) for the remote cases (sigma(s) < 11 Mm(-1) and NOx < 0.6 ppb), while for the polluted cases our estimates are 15 to 60 ppt. These values are within the range of XO2 estimated by an atmospheric chemistry box model (Chemistry As A Box model Application-Module Efficiently Calculating the Chemistry of the Atmosphere (CAABA/MECCA)-3.0).

Structural, spectral and potentiometric characterization, and antimicrobial activity studies of [Zn(phen)(2)(cnge)(H2O)](NO3)(2)∙H2O

An octahedral Zn complex with o-phenanthroline (o-phen) and cyanoguanidine (cnge) has been synthesized and characterized. The crystal structural data show the formation of a ZnN5O core where the metal coordinates to two mutually perpendicular o-phenanthrolines as bidentate ligands [Zn-N bond lengths in the 2.124(2)-2.193(2) angstrom range], the cyanide nitrogen of a cnge [d(Zn-N) = 2.092(2) angstrom, angle(Zn-N-C) = 161.1(2)degrees], and a water molecule [d(Zn-Ow) = 2.112(2) angstrom]. Spectral data (FT-IR, Raman, and fluorescence) and speciation studies are in agreement with the structure found in the solid state and the one proposed to exist in the solution. To evaluate the changes in the microbiological activity of Zn, antibacterial studies were carried out by observing the changes in minimum inhibitory concentration of the complex, the ligands, and the metal against five different bacterial strains. The antibacterial activity of Zn improved upon complexation in three of the tested strains.

Proline dehydrogenase regulates redox state and respiratory metabolism in Trypanosoma Cruzi

Over the past three decades, L-proline has become recognized as an important metabolite for trypanosomatids. It is involved in a number of key processes, including energy metabolism, resistance to oxidative and nutritional stress and osmoregulation. In addition, this amino acid supports critical parasite life cycle processes by acting as an energy source, thus enabling host-cell invasion by the parasite and subsequent parasite differentiation. In this paper, we demonstrate that L-proline is oxidized to Δ(1)-pyrroline-5-carboxylate (P5C) by the enzyme proline dehydrogenase (TcPRODH, E.C. 1.5.99.8) localized in Trypanosoma cruzi mitochondria. When expressed in its active form in Escherichia coli, TcPRODH exhibits a Km of 16.58±1.69 µM and a Vmax of 66±2 nmol/min mg. Furthermore, we demonstrate that TcPRODH is a FAD-dependent dimeric state protein. TcPRODH mRNA and protein expression are strongly upregulated in the intracellular epimastigote, a stage which requires an external supply of proline. In addition, when Saccharomyces cerevisiae null mutants for this gene (PUT1) were complemented with the TcPRODH gene, diminished free intracellular proline levels and an enhanced sensitivity to oxidative stress in comparison to the null mutant were observed, supporting the hypothesis that free proline accumulation constitutes a defense against oxidative imbalance. Finally, we show that proline oxidation increases cytochrome c oxidase activity in mitochondrial vesicles. Overall, these results demonstrate that TcPRODH is involved in proline-dependant cytoprotection during periods of oxidative imbalance and also shed light on the participation of proline in energy metabolism, which drives critical processes of the T. cruzi life cycle.