The Generalization of the Kinetic Equations and the Spectral Conductivity Function to Anisotropic Systems: Case T-Al_72.5Mn_21.5Fe_6 Complex Metallic Alloy

Electrical conductivity, σ, and thermoelectric power, S, of the monocrystalline T-Al_72.5Mn_21.5Fe_6 complex metallic alloy have been investigated in the temperature range from 2 to 300 K. The crystallographic-direction-dependent measurements were performed along the [0 0 1], [0 1 0] and [1 0 0] directions of the orthorhombic unit cell, where the stacking direction is along the [0 1 0] direction. The electrical conductivity exhibits a very small anisotropy, and in all directions shows the non-metallic behaviour with square root, √T, temperature behaviour and finite value in the T = 0 limit. Spectral conductivity function, σS(E), constructed out of measurements, reflects anisotropy of the experimental data and indicate non-analytic square root like singularity at Fermi level. Asymmetry of the spectral conductivity function has been extracted from the thermoelectric power data

Determination of staphylococcal enterotoxins in cheese by immunoenzyme assays

Staphylococcal food poisoning is one of the most common foodborne diseases resulting from the ingestion of staphylococcal enterotoxins (SEs) preformed in foods by enterotoxigenic strains of coagulase-positive staphylococci (CPS), mainly Staphylococcus aureus. The presence of enterotoxigenic strains of coagulase-positive staphylococci in raw milk during the production process leads to the contamination of products and outbreaks of alimentary intoxication. The problem of Staphylococcus aureus in cheese remains significant on a global level. Domestic cheese contaminated with enterotoxigenic staphylococci can result in the formation of enterotoxin, which can produce foodborne illness when the product is ingested. Due to microbiological contamination, microbiological criteria are tools that can be used in assessing the safety and quality of foods. In order to avoid foodborne illness, the Serbian Regulation on General and Special Conditions for Food Hygiene (Official Gazette of RS, No. 72/10) provides microbiological criteria for staphylococcal enterotoxins in dairy products

The Generalization of the Kinetic Equations and the Spectral Conductivity Function to Anisotropic Systems: Case T-Al72.5Mn21.5Fe6 Complex Metallic Alloy

Electrical conductivity, σ, and thermoelectric power, S, of the monocrystalline T-Al72.5Mn21.5Fe6 complex metallic alloy have been investigated in the temperature range from 2 to 300 K. The crystallographic-direction-dependent measurements were performed along the [0 0 1], [0 1 0] and [1 0 0] directions of the orthorhombic unit cell, where the stacking direction is along the [0 1 0] direction. The electrical conductivity exhibits a very small anisotropy, and in all directions shows the non-metallic behaviour with square root, &radic;T, temperature behaviour and finite value in the T = 0 limit. Spectral conductivity function, σS(E), constructed out of measurements, reflects anisotropy of the experimental data and indicate non-analytic square root like singularity at Fermi level. Asymmetry of the spectral conductivity function has been extracted from the thermoelectric power data.</p

Percolative nature of the dc paraconductivity in the cuprate superconductors

We present an investigation of the planar direct-current (dc) paraconductivity of the model cuprate material HgBa$_2$CuO$_{4+\delta}$ in the underdoped part of the phase diagram. The simple quadratic temperature-dependence of the Fermi-liquid normal-state resistivity enables us to extract the paraconductivity above the macroscopic $T_c$ with great accuracy. The paraconductivity exhibits unusual exponential temperature dependence, with a characteristic temperature scale that is distinct from $T_c$. In the entire temperature range where it is discernable, the paraconductivity is quantitatively explained by a simple superconducting percolation model, which implies that underlying gap disorder dominates the emergence of superconductivity

Identification of mycobiota in Serbian slaughterhouses

Mould growth within slaughterhouses is not acceptable and is considered as both economic and aesthetic problem. Aim of this paper was to determine filamentous moulds in two slaughterhouses by investigating air, water, environment area and equipment. There were a total of 100 samples collected. According to S a m s o n (2004), 6 genera were determined among which Penicillium and Aspergillus were the most frequent. Three Penicillium species were identified; the most frequent were P. brevicompactum and P. solitum. The presence of P. verrucosum was not established. The presence of mycotoxigenic moulds, such as P. brevicompactum, indicates possible contamination of environmental area with mycophenolic acid (MPA). Results of investigation indicated that more comprehensive survey should be made in order to get a better insight of mycobiota in slaughterhouses in Serbia

Efficiency evaluation of a bivalent vaccine in the prophylaxis of mastitis in cows

Mastitis in cows represents one of the most actual problems in intensive dairy production. The longtime different approaches to the treatment of mastitis have not offered a suitable solution, and the problem of mastitis is still present and acute. Prevention of pathogen penetration into the mammary gland, its colonization and multiplication impose a constant need for regular inspections of milk, as well as preventive and therapeutic measures to reduce the incidence of mastitis. Studies in the field of vaccination of ruminants against mastitis pathogens suggest a limited success in obtaining significant results in immunoprophylaxis. Considering the results of other researchers and our own research, and bearing in mind the problems mastitis caused by Staphylococcus aureus and Streptococcus agalactiae represent, the aim of this study was the preparation and testing of an indigenous vaccine prepared with two stable strains, SAU 7 (S. aureus) and SAG 3 (Str.agalactiae). The dose was 5 mL/cow and consisted of inactivated bacterial S. aureus SAU 7 cells in a concentration of 1x1010 cfu/mL and Str. agalactiae SAG 3 in a concentration of 4 x 109 cfu/mL. The number of somatic cells in the milk samples during the whole study period was higher in vaccinated cows in both groups compared with the control, but this difference was not statistically significant. The concentration of immunoglobulin IgG in the milk of vaccinated cows was significantly higher than the concentration of this class of proteins in the milk of unvaccinated cows. [Projekat Ministarstva nauke Republike Srbije, br. III 46002

Molecular typing, pathogenicity factor genes and antimicrobial susceptibility of vancomycin resistant enterococci in Belgrade, Serbia

In this study the distribution of species and antimicrobial resistance among vancomycin resistant enterococci (VRE) recovered from clinical specimens obtained from five hospitals in Belgrade was analyzed. Strains were further characterized by pulsed-field gel electrophoresis (PFGE). Polymerase chain reaction (PCR) was used to investigate the presence of vanA and vanB genes and pathogenicity factor genes. Identification of 194 VRE isolates revealed 154 Enterococcus faecium, 21 Enterococcus faecalis, 10 Enterococcus raffinosus and 9 Enterococcus gallinarum. This study revealed existence of 8 major clones of VRE. PCR determined vanA gene to be present in all of the VRE studied. Esp and hyl genes were present in 29.22% and 27.92% of E. faecium, respectively, and in 76.19% and 0 of E. faecalis, respectively. Esp and hyl genes were not found more frequently in members of predominant clones of E. faecium than in single isolates; nor was their presence connected to invasiveness

Foodborne viruses — an emerging pathogens

Viral foodborne illnesses which have become a significant cause of all reported foodborne illnesses in recent years and considered as an emerging risk in veterinary public health. Foodborne transmission can occur by contamination of food by infected food handlers, by contamination of food during the production process and by consumption of products of animal origin harboring a zoonotic virus. Microbiological genomics studies discovered that noroviruses and hepatitis A viruses were primarily associated with food-handler transmission and sewage-contaminated foods while hepatitis E was associated with consumption of raw or undercooked meat of pig or wild animals. Routine harmonized surveillance of viral outbreaks, and surveillance of virus occurrence in food commodities, in combination with systematic strain typing, and joint expertise from veterinary, food, and clinical microbiologists would be recommended to aid source attribution studies and identify risk prevention measures

Nova istraživanja virulentnosti enterohemoragičnih Esherichia coli u hrani

Most of the genes recently found in pathogenic E. coli encode various factors which directly determine their virulence and pathotype. Two main virulence factors characteristic for enterohemorrhagic E. coli(EHEC) are attaching/effacing lesions and Stx1/Stx2 toxins. Genes responsible for expression of aforementioned virulence factors are heavily regulated by environmental conditions. Low iron concentration induces massive expression of stx1 gene and subsequent toxin synthesis. Stress response of EHEC to starvation, acid challenge, cold shock and osmotic changes which damage DNA, induce 'SOS' response. This response mediated by Rec A protein not only repairs damaged DNA fragments but also induces conversion of lysogenic bacteriophage lifecycle to lytic phase followed by intensive expression of stx2 genes. Bacterial stress adaptation of E. coli to novel technologies and the potential for stress-associated enhanced virulence need to be addressed in more detail to prevent potential risk of disease. An increased understanding of expression of virulence-associated genes will provide information for control of pathogens and increase microbial safety of foods.Većina gena koji su poslednjih godina utvrđeni kod patogenih E. coli kodiraju različite faktore koji direktno utiču na njihovu virulentnost i pripadnost određenom patotipu. Dva glavna faktora virulencije kod enterohemoragičnih E. coli (EHEC)su attaching/effacing lezije Stx1/Stx2 toksini. Geni odgovorni za ekspresiju pomenutih faktora virulencije pod jakim su uticajem uslova sredine. Niska koncentracija gvožđa indukuje jaku ekspresiju stx1 gena i posledičnu sintezu velike količine Stx1 toksina. Stresni odgovor EHEC na manjak hranljivih supstanci, povećanje kiselosti sredine, izloženost hladnoći kao i na promene osmolarnosti, koji oštećuju DNK, indukuje 'SOS' odgovor. 'SOS' reakcija posredovana Rec A proteinom ne samo da popravlja oštećene fragmente DNK molekula, već i pokreće mehanizam konverzije bakteriofaga integrisanog u hromozom E. coli iz lizogene faze u litički ciklus tokom koga dolazi do intenzivne ekspresije stx2 gena. Da bi se preventirao potencijalni rizik nastanka bolesti, neophodno je detaljno proučavati prilagođavanje E. coli novim tehnologijama pripreme i konzervacije hrane i potencijal za stres-indukovanu virulenciju. Dobro poznavanje ekspresije gena odgovornih za virulenciju obezbediće informacije neophodne za kontrolu patogena i povećaće mikrobiološku bezbednost hrane