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

Transmission of common foodborne viruses by meat products

The most common foodborne viruses are single stranded RNA viruses which are adaptable and extremely resistant to environmental stress factors. Usual routes of food contamination are via stool material by persons shedding intestinal virus, or by saliva aerosols generated by shedding persons when coughing. Contamination of meat by animal viruses occurs when good hygienic and manufacturing practice fails. Once within food, viruses cannot replicate since they require living cells for this; hence food is not sensorily altered. Preventive measures in meat processing against pathogenic bacteria frequently have poor antiviral performance, while diagnostic techniques for viruses remain problematic

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

Utjecaj superstrukturiranja na optička i transportna svojstva odabranih slojevitih materijala

Very special electronic phases brought upon by the superstructuring in layered materials have held the interest of researchers for decades. This thesis deals with the effects of the lattice superstructuring on optical and transport properties of pure and doped samples of 1T-TaS2 and 1T-TiSe2. This work brings the first ever analysis of the optical properties of the nearly-commensurate charge density wave (NCCDW) phase of 1T-TaS2 at temperatures below 200 K. Optical response of the NCCDW phase is for the first time analyzed with the nano-composite-like nature of the phase in mind. Modeling of the optical response using the Bruggeman effective medium theory is suggested and demonstrated. As a result, localized surface plasmon feature is identified in the optical spectrum, as well as the asymmetry of the optical phonon modes brought upon by the coupling of spatially distinct nano-sized domains which comprise the material. A novel analysis of the superstructure-related phonon peaks which allows the determination of the charge redistribution over the star-like superstructure is presented. Lastly, this work also presents the study of the 1T-TiSe2 compound, where the analysis is focused on the properties of the high temperature phase of the material. The contributions of electron and hole pockets are resolved for the first time, as well as the spectral weights and the scattering rates for each channel. Calculated energy ranges of the quasi-2D hole band settle the ongoing debate and determine that 1T-TiSe2 in the high-temperature phase is a semimetal, with scattering which gets stronger over a wide interval as the temperature approaches the phase transition.Vrlo posebne elektronske faze koje nastaju superstrukturiranjem slojastih materijala već desetljećima zaokupljaju pažnju istraživača. Ovaj doktorski rad proučava efekte superstrukturiranja kristalne rešetke na optička i transportna svojstva čistih i dopiranih uzoraka 1T-TaS2 i 1T-TiSe2. Rad donosi prvu analizu optičkih svojstava faze približno sumjerljivog vala gustoće naboja (engl. NCCDW) 1T-TaS2 na temperaturama ispod 200 K. Po prvi put je optički odziv NCCDW faze analiziran uzimajući u obzir njenu nanokompozitnu prirodu, te je predloženo i provedeno modeliranje optičkog odziva pomoću Bruggemanove teorije efektivnog medija. Kao rezultat, u optičkom spektru je identificiran učinak lokalnog površinskog plazmona, kao i asimetrija fononskih modova do koje dolazi zbog vezanja optičkog odziva prostorno razdvojenih nano-domena. Nadalje, predložena je nova analiza intenziteta super-strukturnih fononskih vrhova koja omogućava određivanje redistribucije naboja u zvjezdastoj superstrukturi. Napose, ovaj rad predstavlja i istraživanje 1T-TiSe2, gdje je analiza usredotočena na svojstva visokotemperaturne faze materijala. Po prvi put su razlučeni doprinosi elektronskih i šupljinskih pobuđenja, te njihova spektralna težina i jačina raspršenja. Proračuni energijskog raspona kvazi-dvodimenzionalne šupljinske vrpce omogućuju zaključenje dugotrajne debate u korist zaključka da je 1T-TiSe2 u visokotemperaturnoj fazi “polumetal” (engl. semimetal), s raspršenjem koje jača preko vrlo širokog intervala u kojem se temperatura približava točki prijelaza

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

The influence of dietary composition on food preference in Sharplanina Shepherd puppies

Pet food manufacturers aim to balance the palatability with the nutritional value of their products. Ensuring that young canines receive the best nourishment is crucial, while also promoting long-lasting engagement and satisfaction during mealtime. The study aimed to investigate if the nutritional content of food can affect food preferences in 2-month-old Sharplanina shepherd dogs and the development of neophobia when introduced to a new diet. Three different dietary plans were tested, each with varying percentages of an imal-derived proteins (97% in A, 77% in B, and 94% in C). Observations of behavior were documented on camera at the beginning and end of a 10-day feeding cycle. The observations were made during the scheduled feeding times of 7 a.m., noon, and 5 p.m. According to the study, puppies showed neophobic behavior when a new diet was introduced. The puppies displayed a notable decrease in meal rate of sumption, heightened distraction during diet consumption, and increased hesitation on the first day of each new diet, specifically on day 9 and day 10. Post-consumption interest peaked significantly on day 9 and day 10, particularly when dogs consumed diet C. Through the study, it was observed that Diet C had an impact on the puppies’ feed preferences, indicating a possible link between the diet’s nutritional content and their food preferences. Based on the study results, it appears that puppies need at least 9 days to reduce phobia and adapt to new food flavors and feeding schedules

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