Stabilization of a Highly Concentrated Colloidal Suspension of Pristine Metallic Nanoparticles

A colloidal suspension containing a high concentration of metallic nanoparticles (NPs) finds potential applications in flexible electronic printing, nanofluids, healthcare, antifouling coating, and so on. Here, we demonstrate a generic, easily scalable, simple, and contamination-free cryogenic temperature grinding method, which can effectively be used to prepare pristine NPs that can be stabilized in polar liquids in high concentrations. These surfactant-free pristine NPs have been found to remain dispersed in different polar liquids (CH3OH, C2H5OH, glycol, etc.) for weeks. The long-term stability of the NPs in these liquids has been investigated using zeta potential, in situ Fourier transform infrared spectroscopy, indicating electrostatic stabilization for ultrapure, surfactant-free NPs. Furthermore, stabilization of the NPs has been probed with detailed calculations using the Derjaguin Landau Verwey Overbeek theory as well as atomistic molecular dynamics simulation (MD). Experimental measurements along with theoretical calculations categorically indicate that the electrostatic energy is helping these NPs to be stabilized in a polar liquid

Seasonability of protein and others milk components related with quality payment program

Avaliou-se o efeito da variação da qualidade do leite mediante acompanhamento de amostras provenientes de tanques refrigeradores. As 2.970 amostras foram obtidas de outubro/2005 a setembro/2006. Foram realizadas análises de composição, contagem de células somáticas (CCS) e contagem bacteriana total. As condições climáticas foram avaliadas pela temperatura e umidade do ar coletadas em estações meteorológicas distribuídas em todo o estado de São Paulo. No outono, ocorreram os maiores valores para gordura e proteína do leite, 3,65 e 3,21%, respectivamente. Para contagem de células somáticas, foi observado aumento no verão e contagem bacteriana na época da primavera. Foi identificada a influência da época do ano sobre o preço do leite pago dentro de um programa, com valor de bonificação máxima de 7,9% para o outono. Um dos mais importantes itens relacionados com a penalização foi a CCS, a qual pode interferir na qualidade dos produtos finais por meio de alteração da proporção de caseína/proteínas do soro. O efeito da CCS e o da época do ano devem ser considerados na formulação das tabelas de programas de pagamento.This study evaluated the variation of quality of bulk tank milk using 2,970 samples, collected from October 2005 to September 2006. Milk composition analyses, somatic cell count (SCC), and total bacterial count were performed. Climate conditions were evaluated by temperature and relative air humidity collected at meteorological stations throughout São Paulo state. Autumn season was related to the highest values for protein and fat, 3.65 and 3.21%, respectively. For somatic cell count, it was observed an increase in the count in the summer and for bacterial count in the spring. The influence of season on milk price was observed for dairy producers in a program, with maximum bonus of 7.9% in the autumn. One of the most important parameters related to penalty for lower quality of milk was SCC, since it can affect the quality of some dairies by the alteration of casein/whey protein proportion. Therefore, the effects of SCC and season should be considered into the process of formulation of tables for milk payment program.FAPES

Static And Dynamic Properties Of Fibonacci Multilayers

We theoretically investigate static and dynamic properties of quasiperiodic magnetic multilayers. We considered identical ferromagnetic layers separated by non-magnetic spacers with two different thicknesses chosen based on the Fibonacci sequence. Using parameters for Fe/Cr, the minimum energy was determined and the equilibrium magnetization directions found were used to calculate magnetoresistance curves. Regarding dynamic behavior, ferromagnetic resonance (FMR) curves were calculated using an approximation known from the literature. Our numerical results illustrate the effects of quasiperiodicity on the static and dynamic properties of these structures. © 2013 American Institute of Physics.11317Grünberg, P., Schreiber, R., Pang, Y., Brodsky, M.B., Sowers, H., (1986) Phys. Rev. Lett., 57, p. 2442. , 10.1103/PhysRevLett.57.2442Baibich, M.N., Broto, J.M., Fert, A., Nguyen Van Dau, F., Petroff, F., Etienne, P., Creuzet, G., Chazelas, J., (1988) Phys. Rev. Lett., 61, p. 2472. , 10.1103/PhysRevLett.61.2472Binasch, G., Grünberg, P., Saurenbach, F., Zinn, W., (1989) Phys. Rev. B, 39, p. 4828. , 10.1103/PhysRevB.39.4828Prinz, G.A., (1998) Science, 282, p. 1660. , 10.1126/science.282.5394.1660Kools, J.C.S., (1996) IEEE Trans. Magn., 32, p. 3165. , 10.1109/20.508381Stiles, M.D., Zangwill, A., (2002) Phys. Rev. B, 66, p. 014407. , 10.1103/PhysRevB.66.014407Lakys, Y., Zhao, W.S., Devolder, T., Zhang, Y., Klein, J.O., Ravelosona, D., Chappert, C., (2012) IEEE Trans. Magn., 48, p. 2403. , 10.1109/TMAG.2012.2194790Chaves, R.C., Cardoso, S., Ferreira, R., Freitas, P.P., (2011) J. Appl. Phys, 109, pp. 07E506. , 10.1063/1.3537926Vedyayev, A., Dieny, B., Ryzhanova, N., Genin, J.B., Cowache, C., (1994) Europhys. Lett., 25, p. 465. , 10.1209/0295-5075/25/6/012Albuquerque, E.L., Cottam, M.G., (2004) Polaritons in Periodic and Quasiperiodic Structures, , (Elsevier, Amsterdam)Bezerra, C.G., Albuquerque, E.L., (1997) Physica A, 245, p. 379. , 10.1016/S0378-4371(97)00309-9Bezerra, C.G., De Araujo, J.M., Chesman, C., Albuquerque, E.L., (1999) Phys. Rev. B, 60, p. 9264. , 10.1103/PhysRevB.60.9264Bezerra, C.G., De Araujo, J.M., Chesman, C., Albuquerque, E.L., (2001) J. Appl. Phys., 89, p. 2286. , 10.1063/1.1340600Bezerra, C.G., Cottam, M.G., (2002) J. Magn. Magn. Mater., 240, p. 529. , 10.1016/S0304-8853(01)00838-1Bezerra, C.G., Cottam, M.G., (2002) Phys. Rev. B, 65, p. 054412. , 10.1103/PhysRevB.65.054412Mauriz, P.W., Albuquerque, E.L., Bezerra, C.G., (2002) J. Phys.: Condens. Matter, 14, p. 1785. , 10.1088/0953-8984/14/8/308Fullerton, E.E., Conover, M.J., Mattson, J.E., Sowers, C.H., Bader, S.D., (1993) Phys. Rev. B, 48, p. 15755. , 10.1103/PhysRevB.48.15755Machado, L.D., Bezerra, C.G., Correa, M.A., Chesman, C., Pearson, J.E., Hoffmann, A., (2012) Phys. Rev. B, 85, p. 224416. , 10.1103/PhysRevB.85.22441

Genotipagem de Toxoplasma gondii em galinhas domésticas em uma área rural do Rio Grande do Sul, Brasil

Free-range chickens may ingest oocysts of T. gondii present in the environment and consequently harbor virulent strains of this parasite in different tissues, without any clinical signs. Isolation of T. gondii through bioassays on mice and cats from naturally infected chicken tissues has been described in several countries, demonstrating the importance of free-range chickens in the transmission of this parasite. The aim of this study was the genotypic characterization of T. gondii isolates obtained from naturally infected free-range chickens in a rural area of the state of Rio Grande do Sul, Brazil. Brain and heart tissue from 12 chickens seropositive for T. gondii were processed using peptic digestion technique for parasite isolation. From 12 samples subjected to mouse bioassay, nine isolates were obtained. RFLP-PCR genotypic characterization was performed using 11 genetic markers: SAG1, 5'-3'SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29- 2, L358, PK1 and Apico. Genetic characterization of the isolates revealed the presence of five atypical genotypes according to ToxoDB (# 11, # 55, # 64, # 140 and # 163). Our results showed a wide genetic diversity of T. gondii in free-range chickens in this region.Galinhas criadas ao ar livre podem ingerir oocistos de T. gondii presentes no ambiente e, com isso, albergar cepas virulentas desse parasita em diferentes tecidos, sem sinais clínicos. O isolamento de T. gondii por meio de bioensaios em camundongos e gatos, a partir de tecidos de galinhas naturalmente infectadas, tem sido descrito em vários países. Isso demonstra a importância das galinhas caipiras na epidemiologia desse parasita. O objetivo deste trabalho foi caracterizar genotipicamente isolados de T. gondii obtidos de galinhas caipiras naturalmente infectadas em uma área rural do município de Santa Maria, estado do Rio Grande do Sul, Brasil. Fragmentos de cérebro e de coração, de 12 galinhas soropositivas para T. gondii, foram processados pela técnica de digestão péptica para isolamento do parasita. Das 12 amostras submetidas a bioensaio com camundongos, nove isolados foram obtidos. A caracterização genotípica por RFLP-PCR foi realizada utilizando-se 11 marcadores genéticos: SAG1, 5'- 3'SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1 e Apico e revelou a presença de cinco genótipos atípicos de acordo com o ToxoDB (# 11, # 55, # 64, # 140 e # 163). Os resultados mostraram uma ampla diversidade genética de T. gondii em galinhas caipiras nessa região.Fil: Camillo, G.. Universidade Federal de Santa Maria; BrasilFil: Machado, M. E. A.. Universidade Federal de Santa Maria; BrasilFil: Cadore, G.C.. Universidade Federal de Santa Maria; BrasilFil: Bräunig, P.. Universidade Federal de Santa Maria; BrasilFil: Venturini, María Cecilia. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Epizootiología y Salud Pública. Laboratorio de Inmunoparasitología; ArgentinaFil: Pardini, Lais Luján. Universidad Nacional de La Plata. Facultad de Ciencias Veterinarias. Departamento de Epizootiología y Salud Pública. Laboratorio de Inmunoparasitología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; ArgentinaFil: Barros, L.D.. Universidade Estadual de Londrina; BrasilFil: Garcia, J.L.. Universidade Estadual de Londrina; BrasilFil: Sangioni, L.A.. Universidade Federal de Santa Maria; BrasilFil: Vogel, F.S.F.. Universidade Federal de Santa Maria; Brasi

Extreme geographical fixation of variation in the Plasmodium falciparum gamete surface protein gene Pfs48 /45 compared with microsatellite loci

Comparing patterns of genetic variation at multiple loci in the genome of a species can potentially identify loci which are under selection. The large number of polymorphic microsatellites in the malaria parasite Plasmodium falciparum are available markers to screen for selectively important loci. The Pfs48 /45 gene on Chromosome 13 encodes an antigenic protein located on the surface of parasite gametes, which is a candidate for a transmission blocking vaccine. Here, genotypic data from 255 P. falciparum isolates are presented, which show that alleles and haplotypes of five single nucleotide polymorphisms (SNPs) in the Pfs48 /45 gene are exceptionally skewed in frequency among different P. falciparum populations, compared with alleles at 11 microsatellite loci sampled widely from the parasite genome. Fixation indices measuring inter-population variance in allele frequencies (FST) were in the order of four to seven times higher for Pfs48 /45 than for the microsatellites, whether considered (i) among populations within Africa, or (ii) among different continents. Differing mutational processes at microsatellite and SNP loci could generally affect the population structure at these different types of loci, to an unknown extent which deserves further investigation. The highly contrasting population structure may also suggest divergent selection on the amino acid sequence of Pfs48/45 in different populations, which plausibly indicates a role for the protein in determining gamete recognition and compatibility

Dipole model for double meson production in two-photon interactions at high energies

In this work the double vector meson production in two-photon interactions at high energies is investigated considering saturation physics. We extend the color dipole picture for this process and study the energy and virtuality dependence of the forward differential cross section. Comparison with previous results is presented and the contribution of the different photon polarizations is estimated.Comment: 20 pages, 8 figures, 1 table. Version to be published in European Physical Jornal

Influence of scrotal bipartition on spermatogenesis yield and sertoli cell efficiency in sheep

Abstract With the objective to assess the effect of scrotal bipartition on spermatogenesis in sheep, the testes were used from 12 crossbred rams of sheep farms in the municipality of Patos, Paraíba, Brazil, distributed into two groups: GI with six rams with scrotal bipartition, and GII with six rams without scrotal bipartition. The testicular biometry was measured and the testes were collected, fixed in Bouin and fragments were processed to obtain histological slides. The spermatogenesis yield and the Sertoli cell efficiency was estimated by counting the cells of the spermatogenetic line at stage one of the seminiferous epithelium cycle and the Sertoli cells. The results were submitted to analysis of variance with the ASSISTAT v.7.6 program and the mean values were compared by the Student-Newman-Keuls test (SNK) at 5% significance. The testicular biometric parameters did not show statistical difference (p>0.05) between the groups. The meiotic, spermatogenetic and Sertoli cell efficiency were higher in bipartitioned rams (p0.05) between GI and GII. The results indicated that there is superiority in the spermatogenetic parameters of bi-partitioned rams, suggesting that these sheep present, as reported in goats, indication of better reproductive indices