First principles study of structural,electronic and optical properties of AgSbS2

In this work, we study the structural, electronic and optical properties of AgSbS₂, using full-potential linearized augmented plane wave and the pseudopotential plane wave scheme in the frame of generalized gradient approximation. Features such as the lattice constant, bulk modulus and its pressure derivative are reported. Our results suggest a phase transition from AF-IIb phase to rocksalt (B1) phase under high pressure. The calculated band structure and density of states show that the material under load has an indirect energy band gap X→(LГ) for AF-IIb phase (semiconductor) and a negative band gap W→(ГX) for B1 phase (semimetal). The optical properties are analyzed and the origin of some peaks in the spectra is discussed. Besides, the dielectric function, refractive index and extinction coefficient for radiation up to 14 eV have also been reported and discussed.     

External Weather Data Assimilation to Simulate Wind and Temperature Fields in the Region of Gualeguaych~, Argentina

This work shows the comparison between the results of wind and temperature simulation and data weather measurements in low layers near Gualeguaychfi City, Argentine, for 12 h in January 1, 2011. The model ARPS （advanced regional prediction system） with two options in the boundary conditions is used. In such conditions, wave-radiating open （radiative） with relaxation to the initial state were used while otherwise used absorbing boundary conditions data forced from MBLM （meso-scale boundary layer model） operational forecasters used by the National Weather Office. The results of both simulations are compared with data measured by three weather stations located around of the Uruguay River. As both simulations are initialized using the same data, there is a better agreement between the values obtained by forcing the boundary conditions for which are using ＂radiative＂ boundary conditions after 2 h physical time from the start of the simulation.     

Comparison of Coxiella burnetii shedding in milk of dairy bovine, caprine, and ovine herds

The shedding of Coxiella burnetii in bovine, caprine, and ovine milk was measured using PCR, in 3 herds for each species, the bulk tank milk samples of which were positive at the time of their selection. Milk samples of 95 cows, 120 goats, and 90 ewes were sampled over 16 wk, as was the bulk tank milk. The shedding of C. burnetii in vaginal mucus and feces was checked at the beginning of the experiment and 2 mo later. The clinical signs in the selected herds as well as the duration and the shedding routes differed among the 3 species. The cows were asymptomatic and shed C. burnetii almost exclusively in milk. In one of the caprine herds, abortions due to C. burnetii were reported. The goats excreted the bacteria mainly in milk. In contrast, the ewes, which came from flocks with abortions due to Q fever (C. burnetii infection), shed the bacteria mostly in feces and in vaginal mucus. This could explain why human outbreaks of Q fever are more often related to ovine flocks than to bovine herds. These excretions did not seem more frequent when the samples were taken close to parturition. The samples were taken from 0 to 421 d after parturition in bovine herds and from 5 to 119 d and 11 to 238 d after parturition in the caprine and ovine herds, respectively. The shedding in milk was sometimes intermittent, and several animals shed the bacteria but were negative by ELISA: 80% of the ewes were seronegative, underscoring the lack of sensitivity of the ELISA tests available for veterinary diagnosis. The detection of antibodies in milk seems more sensitive than it is in serum.     

Real-time PCR-based detection of Coxiella burnetii in cheeses

In this study, the presence of Coxiella burnetii (Cb) in cheese produced in Southern Italy from milk of cow, buffalo, and small ruminants has been evaluated. Two tests based on real-time PCR assay targeting CB IS1111 element were performed. First an assay based on the use of Taq-Man probe was performed to screen the samples. The positive samples were confirmed using both a SyBr Green test and the evaluation of the melting temperature of the amplicons. In addition, all cheese samples were also tested to determine the milk species utilized (Regulation EC 273/2008). The samples of cheese produced with a milk mix from different species were not included into the study. A total of 169 cheese samples were tested, and the obtained results showed an overall prevalence of Cb of 21.3 % with variation between species. A positivity rate of 39 % was observed in cow’s cheese while Cb DNA was detected in 26 % of cheese samples made from small ruminants’ milk. However, the bacterium was found only in 6.9 % of buffalo’s cheese samples. A direct association between prevalence and milk used for the production was highlighted (χ ²  = 19.12). The statistical analysis of the prevalence in the samples from cattle and small ruminants compared with those from buffalo shows an OR of 8.4 and 4.9, respectively.     

Use of a fluorescence front face technique for measurement of lipid oxidation during refrigerated storage of chicken meat

Lipid oxidation in chicken breast was measured during refrigerated storage in air by front face fluorescence and by thiobarbituric acid techniques. Three chicken genotypes were compared: Standard (fast-growing line), Certified (medium-growing line) and Label (slow-growing line). Lipid oxidation was stable during the first 3 days of storage and then increased in the certified and label animal groups. Standard animals were very stable towards lipid oxidation. This study showed a good correlation between fluorescence intensity and thiobarbituric acid reactive substances measurements. Front face fluorescence technique can be used as a valuable index of lipid oxidation in chicken meat.