Sao Paulo State University

About: Sao Paulo State University is a education organization based out in São Paulo, Brazil. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 55715 authors who have published 100436 publications receiving 1375332 citations.

Screening of bacterial strains for pectinolytic activity: characterization of the polygalacturonase produced by Bacillus sp

Abstract: One hundred sixty eight bacterial strains, isolated from soil and samples of vegetablein decomposition, were screened for the use of citrus pectin as the sole carbon source.102 were positive for pectinase depolymerization in assay plates as evidenced by clearhydrolization halos. Among them, 30% presented considerable pectinolytic activity.The cultivation of these strains by submerged and semi-solid fermentation forpolygalacturonase production indicated that five strains of Bacillus sp produced highquantities of the enzyme. The physico-chemical characteristics, such as optimum pHof 6.0 Œ 7.0, optimum temperatures between 45 o C and 55”C, stability at temperaturesabove 40”C and in neutral and alkaline pH, were determined.Key words: Bacillus sp, polygalacturonase, pectinolytic activityINTRODUCTIONMany plant-pathogenic bacteria and fungi areknown to produce pectolytic enzymes useful forinvading host tissues. Moreover, theses enzymes areessential in the decay of dead plant material bynonpathogenic microorganisms and thus assist inrecycling carbon compounds in the biosphere (2).Pectinases include depolymerizing anddemethoxylating enzymes. Depolymerizing enzymesare polygalacturonase (EC 3.2.1), which cleaves theα-1,4 glycosidic bonds between two galacturonicacid residues, and pectin-lyase (EC 4.2.2), whichcatalyses a β-elimination reaction between twomethylated residues (3). De-esterifying enzymesinclude pectin-esterase (EC 3.1.1), which catalysesthe demethoxylation of methylated pectin,producing methanol and pectin (20).Preparations containing pectin-degradingenzymes have been extensively used to improve thestability of fruit and vegetable nectars and in theclarification of fruit juices and wines (5, 13, 21, 23,24). Currently, they are widely used in industry forretting of natural fibers and extraction of oils fromvegetable and citrus peels (4, 6).The enzymes preparations used in the foodindustry are of fungal origin because fungi are potentproducers of pectic enzymes and the optimal pH offungal enzymes is very close to the pH of many fruitjuices, which range from pH 3,0 to 5,5 (26). Suchpreparations are not suited for production ofvegetable purOes or other preparations in which pH

Multiferroicity in an organic charge-transfer salt that is suggestive of electric-dipole-driven magnetism

Abstract: Multiferroics, showing simultaneous ordering of electrical and magnetic degrees of freedom, are remarkable materials as seen from both the academic and technological points of view. A prominent mechanism of multiferroicity is the spin-driven ferroelectricity, often found in frustrated antiferromagnets with helical spin order. There, as for conventional ferroelectrics, the electrical dipoles arise from an off-centre displacement of ions. However, recently a different mechanism, namely purely electronic ferroelectricity, where charge order breaks inversion symmetry, has attracted considerable interest. Here we provide evidence for ferroelectricity, accompanied by antiferromagnetic spin order, in a two-dimensional organic charge-transfer salt, thus representing a new class of multiferroics. We propose a charge-order-driven mechanism leading to electronic ferroelectricity in this material. Quite unexpectedly for electronic ferroelectrics, dipolar and spin order arise nearly simultaneously. This can be ascribed to the loss of spin frustration induced by the ferroelectric ordering. Hence, here the spin order is driven by the ferroelectricity, in marked contrast to the spin-driven ferroelectricity in helical magnets.

Search for physics beyond the standard model in dilepton mass spectra in proton-proton collisions at √s=8 TeV

Abstract: Dimuon and dielectron mass spectra, obtained from data resulting from proton-proton collisions at 8 TeV and recorded by the CMS experiment, are used to search for both narrow resonances and broad deviations from standard model predictions. The data correspond to an integrated luminosity of 20.6 (19.7) fb^(−1) for the dimuon (dielectron) channel. No evidence for non-standard-model physics is observed and 95% confidence level limits are set on parameters from a number of new physics models. The narrow resonance analyses exclude a Sequential Standard Model Z'_(SSM) resonance lighter than 2.90 TeV, a superstring-inspired Z'_ψ lighter than 2.57 TeV, and Randall-Sundrum Kaluza-Klein gravitons with masses below 2.73, 2.35, and 1.27 TeV for couplings of 0.10, 0.05, and 0.01, respectively. A notable feature is that the limits have been calculated in a model-independent way to enable straightforward reinterpretation in any model predicting a resonance structure. The observed events are also interpreted within the framework of two non-resonant analyses: one based on a large extra dimensions model and one based on a quark and lepton compositeness model with a left-left isoscalar contact interaction. Lower limits are established on MS, the scale characterizing the onset of quantum gravity, which range from 4.9 to 3.3 TeV, where the number of additional spatial dimensions varies from 3 to 7. Similarly, lower limits on Λ, the energy scale parameter for the contact interaction, are found to be 12.0 (15.2) TeV for destructive (constructive) interference in the dimuon channel and 13.5 (18.3) TeV in the dielectron channel.