Growth of Salmonella enteritidis in artificially contaminated eggs: the effects of inoculum size and suspending media

Growth profiles of two isolates of Salmonella enteritidis phage type (PT) 4 inoculated into either the albumen of whole shell eggs or into separated albumen were found to be markedly affected by the size of the inoculum and the composition of the medium used to suspend the cells prior to inoculation. Using our model with an inoculum of two cells, multiplication of the Salmonella was not seen in 93% of eggs held at 20 degreesC for 8 days. In approximately 7% of eggs, however, growth occurred during the 8 days of storage. If the inoculum equaled or exceeded 25 cells per egg when eggs were subsequently stored at 20 degreesC, or 250 cells per egg when eggs were stored at 30 degreesC, high levels of growth of Salmonella in the egg occurred significantly more frequently than when the inoculum was two cells. High levels of growth were also seen more frequently if the inoculum was suspended in buffered peptone water or maximal recovery diluent rather than in phosphate buffered saline. Growth of Salmonella in separated albumen occurred very infrequently (1.1% of samples) at low inoculum levels and did not become significant until the inoculum was 250 cells or greater. Growth in the albumen was unaffected by the composition of the suspending medium. Provided that the inoculum was approximately 2 cells per egg and the bacteria were suspended in PBS, observed growth profiles of S. enteritidis inoculated into the albumen of whole eggs resembled those in naturally contaminated eggs. (C) 2001 Elsevier Science B.V. All rights reserved.

Padé approximants for the acoustical properties of rigid frame porous media with pore size distributions

Expressions for the viscosity correction function, and hence bulk complex impedance, density, compressibility, and propagation constant, are obtained for a rigid frame porous medium whose pores are prismatic with fixed cross-sectional shape, but of variable pore size distribution. The lowand high-frequency behavior of the viscosity correction function is derived for the particular case of a log-normal pore size distribution, in terms of coefficients which can, in general, be computed numerically, and are given here explicitly for the particular cases of pores of equilateral triangular, circular, and slitlike cross-section. Simple approximate formulae, based on two-point Pade´ approximants for the viscosity correction function are obtained, which avoid a requirement for numerical integration or evaluation of special functions, and their accuracy is illustrated and investigated for the three pore shapes already mentioned

Energy and system size dependence of phi meson production in Cu plus Cu and Au plus Au collisions

We study the beam-energy and system-size dependence of phi meson production (using the hadronic decay mode phi -> K(+) K(-)) by comparing the new results from Cu + Cu collisions and previously reported Au + Au collisions at root s(NN) = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented in this Letter are from mid-rapidity (vertical bar y vertical bar < 0.5) for 0.4 < p(T) < 5 GeV/c. At a given beam energy, the transverse momentum distributions for phi mesons are observed to be similar in yield and shape for Cu + Cu and Au + Au colliding systems with similar average numbers of participating nucleons. The phi meson yields in nucleus-nucleus collisions, normalized by the average number of participating nucleons, are found to be enhanced relative to those from p + p collisions. The enhancement for phi mesons lies between strange hadrons having net strangeness = 1 (K(-) and <(A)over bar>) and net strangeness = 2 (Xi). The enhancement for phi mesons is observed to be higher at root s(NN) = 200 GeV compared to 62.4 GeV. These observations for the produced phi(s (s) over bar) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems. (C) 2009 Elsevier B.V. All rights reserved.

Aberrant crypt foci and colon cancer: comparison between a short- and medium-term bioassay for colon carcinogenesis using dimethylhydrazine in Wistar rats

Aberrant crypt foci (ACF) in the colon of carcinogen-treated rodents are considered to be the earliest hallmark of colon carcinogenesis. In the present study the relationship between a short-term (4 weeks) and medium-term (30 weeks) assay was assessed in a model of colon carcinogenesis induced by dimethylhydrazine (DMH) in the rat. Six-week-old male Wistar rats were given subcutaneous injections of DMH (40 mg/kg) twice a week for 2 weeks and killed at the end of the 4th or 30th week. ACF were scored for number, distribution pattern along the colon and crypt multiplicity in 0.1% methylene-blue whole-mount preparations. ACF were distinguished from normal crypts by their larger size and elliptical shape. The incidence, distribution and morphology of colon tumors were recorded. The majority of ACF were present in the middle and distal colon of DMH-treated rats and their number increased with time. By the 4th week, 91.5% ACF were composed of one or two crypts and 8.5% had three or more crypts, while by the 30th week 46.9% ACF had three or more crypts. Thus, a progression of ACF consisting of multiple crypts was observed from the 4th to the 30th week. Nine well-differentiated adenocarcinomas were found in 10 rats by the 30th week. Seven tumors were located in the distal colon and two in the middle colon. No tumor was found in the proximal colon. The present data indicate that induction of ACF by DMH in the short-term (4 weeks) assay was correlated with development of well-differentiated adenocarcinomas in the medium-term (30 weeks) assay.

Corn texture and particle size in broiler diets

The objective of this study was to evaluate the effect of corn texture and the particle size on broiler performance, carcass yield, nutrient digestibility, and digestive organ morphometrics. In Experiment I, 720 male Cobb chicks were distributed in a completely randomized experimental design with a 2 x 3 factorial arrangement, consisting two corn textures (dented and hard) and three corn particle sizes, was applied, with four replicates of 30 birds each. Corn particle size was classified according to geometric mean diameter (GMD) as fine - 0.46 mm; medium - 0.73 mm, and coarse - 0.87 mm. In Experiment II, 120 broiler chicks were used to evaluate corn digestibility during the periods of 16 to 22 days and 35 to 41 days of age, using the method of total excreta collection. In Experiment I, corn particle size influenced body weight, average weight gain, feed intake and feed conversion ratio of 21-day-old birds. Corn texture and particle size did not affect the performance of 42-day-old broilers or carcass traits. In Experiment II, there was no influence of corn texture and particle size on digestive organ weights. Dented corn increased nitrogen excretion in the first trial, and hard corn improved dry matter digestibility in the second metabolic trial. Corn with fine particle size promotes better performance of broilers at 21 days of age. Hard corn results in higher dry matter digestibility and lower nitrogen excretion, and consequently higher production factor in 42-day-old broilers.

Forest fragment size and microhabitat effects on palm seed predation

The establishment of plant species depends crucially on where the seeds are deposited. However, since most studies have been conducted in continuous forests, not much is known about the effects of forest fragmentation on the maintenance of abiotic and biotic characteristics in microhabitats and their effects on seed survival. in this study, we evaluated the effects of forest fragmentation on the predation upon the seeds of the palm Syagrus romanzoffiana in three microhabitats (interior forest, forest edge and gaps) in eight fragments of semi-deciduous Atlantic forest ranging in size from 9.5 ha to 33,845 ha in southeastern Brazil. Specifically, we examined the influence of the microhabitat structure, fauna and fragment size on the pattern of seed predation. Fragments < 100 ha showed similar abiotic and biotic characteristics to those of the forest edge, with no seed predation in these areas. Forest fragments 230-380 ha in size did not present safe sites for S. romanzoffiana seed survival and showed high seed predation intensity in all microhabitats evaluated. In fragments larger than 1000 ha, the seed predation was lower, with abiotic and biotic differences among gaps, interior forests and forest edges. In these fragments, the survival of S. romanzoffiana seeds was related to squirrel abundance and interior forest maintenance. Based on these results, we concluded that there are no safe sites for S. romanzoffiana seed establishment in medium- and small-sized fragments as result of the biotic and abiotic pressure, respectively We suggest that on these forest fragments, management plans are needed for the establishment of S. romanzoffiana, such as interior forest improvement and development in small-sized sites in order to minimize the edge effects, and on medium-sized fragments, we suggest post-dispersal seed protection in order to avoid seed predation by vertebrates. our findings also stress the importance of assessing the influence of forest fragmentation on angiosperm reproductive biology as part of the effective planning for the management of fragmented areas. (c) 2006 Elsevier Ltd. All rights reserved.

Performance of a reciprocal shaker in mechanical dispersion of soil samples for particle-size analysis

A dispersão da amostra de solo é uma etapa fundamental da análise granulométrica, sendo realizada mediante o uso de dispersantes químicos e agitação mecânica. O objetivo deste trabalho foi avaliar a eficiência de mesa agitadora reciprocante de baixa rotação na dispersão mecânica de amostras de solos de diferentes classes texturais. Foram realizadas análises granulométricas em 61 amostras com quatro repetições, empregando o método da pipeta para determinação da fração argila e tamisagem para determinação das frações areia grossa, areia fina e areia total, sendo o silte determinado por diferença. Na avaliação de desempenho, os resultados obtidos com uso da mesa agitadora reciprocante (MAR) foram comparados com dados disponíveis para as mesmas amostras oriundos de relatórios do Ensaio de Proficiência IAC para Laboratórios de Análises de Solos - Prolab/IAC. Análises de acurácia foram realizadas com base nos valores dos intervalos de confiança definidos para cada fração granulométrica componente de cada amostra ensaiada. Indicadores gráficos também foram utilizados na comparação de dados, por meio de dispersão e ajuste linear. A estatística descritiva indicou preponderância de baixa variabilidade em mais de 90 % dos resultados obtidos para as amostras de texturas arenosa, média e argilosa e em 68 % dos obtidos para as amostras de textura muito argilosa, indicando boa repetibilidade dos resultados obtidos com a MAR. Média variabilidade foi mais frequentemente associada à fração silte, seguida da fração areia fina. Os resultados das análises de sensibilidade indicam acurácia de 100 % nas três frações granulométricas - areia total, silte e argila - para todas as amostras analisadas pertencentes às classes texturais muito argilosa, argilosa e média. Para as nove amostras de textura arenosa, a acurácia média foi de 85,2 %, e os maiores desvios ocorreram em relação à fração silte. Nas aproximações lineares, coeficientes de correlação igual (silte) ou superiores (areia total e argila) a 0,93, bem como diferenças menores do que 0,16 entre os coeficientes angulares das retas e o valor unitário, indicam alta correlação entre os resultados de referência (Prolab/IAC) e os obtidos nos ensaios com a MAR. Conclui-se pelo desempenho satisfatório da mesa agitadora reciprocante de baixa rotação para dispersão mecânica de amostras de solo de diferentes classes texturais para fins de análise granulométrica, permitindo recomendar o uso alternativo do equipamento quando se emprega agitação lenta. As vantagens do uso do equipamento nacional incluem o baixo custo, a possibilidade de análise simultânea de grande número de amostras e o uso de frascos comuns, de vidro ou de plástico, baratos e de fácil reposição.

Distribution of Cr, Ni, Cu, Cd and Pb in different molecular size of humic fractions extracted from water and sediment samples collected at Anhumas reservoir - Araraquara/SP

In this work was studied the distribution of Cr, Ni, Cu, Cd and Pb in humic fractions with different molecular size. The HS were extracted from waters (AHS), surface sediments (HESS), interface water sediment (HSIS) and bottom sediment (HSBS) collected in the Anhumas surface water collection reservoir, located in the district of Araraquara - São Paulo State Brazil. The humic substances were extracted by procedures recommended by International Humic Substances Society (IHSS). After purification by dialysis, the humic substances were fractionated using a multistage tangential flow ultrafiltration system. The fractionation patterns of HS characterized a mass distribution relatively uniform among the fractions with different molecular sizes, with larger values in the fractions F-2 (20.8%) and F-4 (23.8%), Except for the ions Pb(II) and Cu(II), which presented relatively higher concentrations in the fractions F-2 and F-4, respectively. In general, chromium, nickel, cadmium and lead have similar distributions in the five fractions with larger and medium molecular sizes (F-1 to F-5). With relation to the mass distributions in the different humic substances fractions extracted from sediment samples collected at three depth, they presented 42-48% of HS in the fractions with larger molecular sizes (F-1 and F-2), 29-31% in the middle fractions (F-3 and F-4) and 13-20% in the fractions with smaller molecular sizes (F-5 and F-6). In general, the metallic ions presented distributions similar among the respective fractions F-1 to F-6, Exceptions for Pb(II) and M(II) in surface sediment with concentrations relatively smaller in the fractions F-2 and F-4, respectively,

Seed size and genotype effects on maize (Zea mays L.) yield under different technology levels

Final plant population in maize crop was used as a basis to identify the technology level of a given farmer. Final population of 50,000 plants/hectare was considered as an indication of a high technology level farmer; 35,000 of a medium, and 20,000 of a low technology level farmer. These populations were artificially obtained for the hybrids HT-2X, BR-201, and BR-205 from small, medium and large seeds. The results showed the triple cross hybrid HT-2X to be the most indicated for low technology level regions, due to its lesser sensitivity to variations in seed size and also to its significant outyielding of the other two hybrids. The double cross hybrids BR-201 and BR-205 exhibited much higher sensitivity to variations in seed size so that if they have to be used in a low technology region, the most recommended procedure would be to make use of the largest possible seeds. In conclusion, genotype and seed size seem to be factors capable of compensating for plant population reductions in maize crops. The more prolific hybrids and the largess seeds are more indicated for low technology level regions.

Investigation of the systems silica and silica containing chromium in alcohol medium

The purpose of this work is to obtain micrometer sized spherical particles of silica and silica-chromium from sodium silicate. Spherical particles were prepared by sol-gel method from hydrolysis to polycondensation of aqueous sodium silicate in alcohol medium. Chromium was added to the system for some samples. Compositions and morphologies were achieved by changing the precipitation agent. X-ray diffractometry, electrophoretic mobility, infrared spectroscopy and scanning electron microscopies were carried out on these particles to identify phases, determine particle mobility, morphology, particle sizes, shapes and order at short distance. Non-crystalline silica particles with spherical shapes and micrometric size were obtained. The surface potentials of the silica particles differed from that of the silica-chromium particles. (C) 1999 Elsevier B.V. B.V. All rights reserved.

Yield and fruit size distribution of processing tomato cultivars

The productivity and fruit size distribution of 28 processing tomato cultivars were analyzed to determine the ones with potential for fresh market. The experiment was done in Jaboticabal-SP, Brazil (21o15'22'' South, 48o18'58'' West, altitude 595 m), in a Haplorthox soil, from June to December. The cultivars H 7155, Hypeel 108, Andino, U 573, H 9036, Ipa 6, H 9494, AG 33, Yuba, RPT 1294, AG 72, Peelmech, Curicó, Hypeel 45, RPT 1478, H 9492, H 9498, H 2710, Hitech 45, Halley, Botu 13, H 9553, U 646, NK 1570, AG 45, RPT 1095, RPT 1570 and PSX 37511 were evaluated. The experimental design was randomized blocks, with four repetitions, and five plants per experimental unit. Fruits harvested from each experimental unit were counted, classified by transversal diameter (large, medium, small, very small and cull) and then weighed. Cultivars AG 72, H 9498, Hypeel 45, RPT 1095 and Curicó yielded more than 70 fruits per plant, on average. The total production per plant of cultivars AG 72, H 9498, Hypeel 45, H 7155, Hypeel 108, Halley, Hitech, RPT 1095, H 9494, H 9036 and Curicó was greater than 4 kg. Considering the weight of large and medium fruits, categories which are important for fresh market, the cultivars H 2710, Botu 13, U 573, Hypeel 45, Yuba, RPT 1294 and Ipa 6 presented values above 50% for production.

Promoting corporate social responsibility in small and medium enterprises in the Caribbean: survey results

Includes bibliography

Ethanol electro-oxidation in an alkaline medium using Pd/C, Au/C and PdAu/C electrocatalysts prepared by electron beam irradiation

Carbon-supported Pd, Au and bimetallic PdAu (Pd:Au 90:10, 50:50 and 30:70 atomic ratios) electrocatalysts were prepared using electron beam irradiation. The obtained materials were characterized by energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and their catalytic activities toward ethanol electro-oxidation were evaluated in an alkaline medium using electrochemical techniques, in situ attenuated total reflectance Fourier transformed infrared spectroscopy (ATR-FTIR) analysis and a single alkaline direct ethanol fuel cell (ADEFC). EDX analyses showed that the actual Pd: Au atomic ratios were very similar to the nominal ones. X-ray diffractograms of PdAu/C electrocatalysts evidenced the presence of Pd-rich (fcc) and Au-rich (fcc) phases. TEM analysis showed a homogeneous dispersion of nanoparticles on the carbon support, with an average size in the range of 3-5 nm and broad size distributions. Cyclic voltammetry (CV) and chronoamperometry (CA) experiments revealed the superior ambient activity toward ethanol electro-oxidation of PdAu/C electrocatalysts with Pd: Au ratios of 90:10 and 50:50. In situ ATR-FTIR spectroscopy measurements have shown that the mechanism for ethanol electro-oxidation is dependent on catalyst composition, leading to different reaction products, such as acetaldehyde and acetate, depending on the number of electrons transferred. Experiments on a single ADEFC were conducted between 50 and 900 C, and the best performance of 44 mW cm-2 in 2.0molL-1 ethanol was obtained at 850C for the Pd:Au 90:10 catalysts. This superior performance is most likely associated with enhancement of ethanol adsorption on Pd, oxidation of the intermediates, the presence of gold oxide-hydroxyl species, low mean particle diameters and better distribution of particles on the support. © 2013 Elsevier Ltd. All rights reserved.

Thermoplastic polyesters and Co-polyesters derived from vegetable oil: synthesis and optimization of melt polycondensation for medium and long chain poly(omega-hydroxyfatty acid)s and their ester derivatives

The synthesis of a series of omega-hydroxyfatty acid (omega-OHFA) monomers and their methyl ester derivatives (Me-omega-OHFA) from mono-unsaturated fatty acids and alcohols via ozonolysis-reduction/crossmetathesis reactions is described. Melt polycondensation of the monomers yielded thermoplastic poly(omega-hydroxyfatty acid)s [-(CH2)(n)-COO-](x) with medium (n = 8 and 12) and long (n = 17) repeating monomer units. The omega-OHFAs and Me-omega-OHFAs were all obtained in good yield (>= 80%) and purity (>= 97%) as established by H-1 NMR, Fourier Transform infra-red spectroscopy (FT-IR), mass spectroscopy (ESI-MS) and high performance liquid chromatography (HPLC) analyses. The average molecular size (M-n) and distribution (PDI) of the poly(omega-hydroxyfatty acid)s (P(omega-OHFA)s) and poly(omega-hydroxyfatty ester) s (P(Me-omega-OHFA) s) as determined by GPC varied with organo-metallic Ti(IV) isopropoxide [Ti(OiPr)(4)] polycondensation catalyst amount, reaction time and temperature. An optimization of the polymerization process provided P(omega-OHFA) s and P(Me-omega-OHFA) s with M-n and PDI values desirable for high end applications. Co-polymerization of the long chain (n = 12) and medium chain (n = 8) Me-omega-OHFAs by melt polycondensation yielded poly(omega-hydroxy tridecanoate/omega-hydroxy nonanoate) random co-polyesters (M-n = 11000- 18500 g mol(-1)) with varying molar compositions.

Bridging hydraulic diffusivity from aquifer to particle-size scale: a study on loess sediments from southwest Hungary

In situ megascale hydraulic diffusivities (D) of a confined loess aquifer were estimated at various scales (10 <= L <= 1500 m) by a finite difference model, and laboratory microscale diffusivities of a loess sample by empirical formulas. A scatter plot reveals that D fits to a single power function of L, providing that microscale diffusivities are assigned to L = 1 m and that differences in diffusivity observed between micro- and megascales are assigned to medium heterogeneity appraised by variations in the curvature and slope of natural hydraulic head waves propagating through the aquifer. Subsequently, a general power relationship between D and L is defined where the base and exponent terms stand for the aquifer storage capability under a confined regime of flow, for the microscale hydraulic conductivity and specific yield of loess, and for the changes in curvature and slope of hydraulic head waves relative to values defined at unit scale.[GRAPHICS]Editor Z.W. Kundzewicz