Electron-phonon coupling in crystalline organic semiconductors: Microscopic evidence for nonpolaronic charge carriers

We consider electron(hole)-phonon coupling in crystalline organic semiconductors, using naphthalene for our case study. Employing a first-principles approach, we compute the changes in the self-consistent Kohn-Sham potential corresponding to different phonon modes and go on to obtain the carrier-phonon coupling matrix elements (vertex functions). We then evaluate perturbatively the quasiparticle spectral residues for electrons at the bottom of the lowest-unoccupied- (LUMO) and holes at the top of the highest-occupied (HOMO) band, respectively obtaining $Z_e\approx 0.74$ and $Z_h\approx 0.78$. Along with the widely accepted notion that the carrier-phonon coupling strengths in polyacenes decrease with increasing molecular size, our results provide a strong microscopic evidence for the previously conjectured nonpolaronic nature of band-like carriers in these systems.Comment: final, published versio

Thermal mass impact on energy performance of a low, medium and heavy mass building in Belgrade

Heavy mass materials used in building structures and architecture can significantly affect building energy performance and occupant comfort. The purpose of this study was to investigate if thermal mass can improve the internal environment of a building, resulting in lower energy requirements from the mechanical systems. The study was focused on passive building energy performance and compared annual space heating and cooling energy requirements for an office building in Belgrade with several different applications of thermal mass. A three-dimensional building model was generated to represent a typical office building. Building shape, orientation, glazing to wall ratio, envelope insulation thickness, and indoor design conditions were held constant while location and thickness of building mass (concrete) was varied between cases in a series of energy simulations. The results were compared and discussed in terms of the building space heating and cooling energy and demand affected by thermal mass. The simulation results indicated that with addition of thermal mass to the building envelope and structure: 100% of all simulated cases experienced reduced annual space heating energy requirements, 67% of all simulated cases experienced reduced annual space cooling energy requirements, 83% of all simulated cases experienced reduced peak space heating demand and 50% of all simulated cases experienced reduced peak space cooling demand. The study demonstrated that there exists a potential for reducing space heating and cooling energy requirements with heavy mass construction in the analyzed climate region (Belgrade, Serbia)

Tribological Potential of Hybrid Composites Based on Zinc and Aluminium Alloys Reinforced with SiC and Graphite Particles

The paper reviews contemporary research in the area of hybrid composites based on zinc and aluminium alloys reinforced with SiC and graphite particles. Metal matrix composites (MMCs) based on ZA matrix are being increasingly applied as light-weight and wear resistant materials. Aluminium matrix composites with multiple reinforcements (hybrid AMCs)are finding increased applications because of improved mechanical and tribological properties and hence are better substitutes for single reinforced composites. The results of research show that the hybrid composites possess higher hardness, higher tensile strength, better wear resistance and lower coefficient of friction when compared to pure alloys

Kinetics and mechanism of sphalerite leaching by sodium nitrate in sulphuric acid solution

Interest for application of hydrometallurgical processes in a processing of complex sulphide ores and concentrates has increased in recent years. Their application provides better metal recoveries and reduced emission of gaseous and toxic ageneses in the environment. The kinetics and mechanism of sphalerite leaching from complex sulphide concentrate with sulphuric acid and sodium nitrate solution at standard conditions was presented in this paper. The influences of temperature and time on the leaching degree of zinc were investigated and kinetic analysis of the process was accomplished. With temperature increasing from 60 to 90°C, the zinc leaching increased from 25.23% to 71.66% after 2 hours, i.e. from 59.40% to 99.83% after 4 hours. The selected kinetic model indicated that the diffusion through the product layer was the rate-controlling step during the sphalerite leaching. The activation energy was determined to be 55 kJ/mol in the temperature range 60-90°C. XRD, light microscopy and SEM/EDX analyses of the complex concentrate and leach residue confirmed formation of elemental sulphur and diffusion-controlled leaching mechanism

Phase behaviors of binary mixtures composed of banana-shaped and calamitic mesogens

In this work, five mixtures with different concentrations of banana-shaped and calamitic compounds have been prepared and subsequently studied by polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction on non-oriented samples. The phase sequences and molecular parameters of the binary systems are presented

Ispitivanje uticaja infekcije salonelama na pojavu kampilobakterioze kod pilića u eksperimentalnim uslovima

Meat, table eggs and their products are very important in human nutrition. Therefore, it is necessary to monitor the health status of commercial flocks as much as the quality of poultry products in the food chain. Campylobacter sp. and Salmonella sp. are widely distributed in nature. The influence of these bacteria on animal health depends on the immune response. If animals are not immunologicaly compromised, the infection is latent and clinical symptoms are absent. Unlike animals, these bacteria cause serious diseases in humans and the morbidity is quite high. The main transfer of infection to humans is via poultry products. The goal of this work was to study the role of Salmonella in artificially infected chickens onto the outcome of clinical campylobacteriosis. It is certain that salmonella infection in poultry damages the immune system of chickens, enabling Campylobacter to multiply and subsequently induce a disease. Three groups of chickens were included in the experiment. The first group received a suspension of field strain of Campylobacter jejuni (C. jejuni) and Salmonella enterica serovar Enteritidis (S. Enteritidis). The second group received an inoculum prepared from the field isolate of Campylobacter jejuni and the third group received the field isolate of Salmonella enterica serotype Enteritidis, only. In artificially infected chickens Campylobacter and Salmonella were confirmed by isolation and identification according to morphological, cultural and biochemical properties. Humoral immune response of infected chickens was monitored using the complement fixation test (CFT). In chickens infected with C. jejuni and S. Enteritidis the clinical symptoms were recorded. The results from this experiment show that salmonella infection damages the immune system of the chickens enabling Campylobacter to alter the health status of the host.Značajno mesto u ishrani ljudi zauzimaju meso i jaja živine, kao i različiti proizvodi od mesa i jaja. Kontinuirana kontrola zdravstvenog statusa živine u lancu proizvodnje jednako je važna kao i kontrola njihovih proizvoda namenjenih za ishranu ljudi. Uzročnici poput kampilobakterija i salmonela široko su rasprostranjeni. u prirodi. Uticaj ovih bakterija na zdravlje životinja zavisi od imunskog statusa jedinki i u većini slučajeva kod imunološki nekompromitovanih jedinki infekcija ovim bakterijama ne dovodi do kliničkih simptoma. Za razliku od životinja, kod ljudi ove bakterije dovode do ozbiljnih kliničkih simptoma sa pojavom morbiditeta u visokom procentu. Njihovo prisustvo u proizvodima od živine, predstavlja jedan od glavnih puteva prenošenja ovih patogena koji izazivaju bolesti ljudi putem hrane. U ovom radu, ispitivanje je imalo za cilj da se kod živine veštački inficirane salmonelom ispita njen uticaj na kliničko ispoljavanje kampilobakterioze. Sigurno je da infekcija živine salmonelom utiče na imunološki sistem dovodeći do njegovog iscrpljivanja i opterećenosti što će omogućiti kampilobakterijama da se umnože do one mere kada će se pojaviti klinički znaci i razviti kampilobakterioza. U eksperimentalnim uslovima ispitivanje je izvedeno na tri grupe od po 30 pilića. Prvoj grupi je peroralno inokulisana suspenzija terenskih izolata Campylobacter jejuni i Salmonella enterica serovar Enteritidis; drugoj grupi peroralno je inokulisana suspenzija terenskog izolata Campylobacter jejuni i trećoj grupi peroralno je inokulisana suspenzija terenskog izolata Salmonella enterica serovar Enteritidis. Prisustvo Campylobacter jejuni i Salmonella Enteritidis u organizmu veštački inficiranih pilića potvrđeno je reizolacijom uzročnika, a identifikacija izolovanih bakterija vršena je na osnovu njihovih morfoloških, kulturelnih i biohemijskih osobina. Imunološki odgovor inficirane živine i titar specifičnih antitela, kao i kretanje humoralnog imunskog odgovora na antigene Campylobacter jejuni kod eksperimentalnih pilića, praćeno je primenom reakcije vezivanja komplementa. Kod pilića inficiranih sojem Campylobacter jejuni i Salmonella Enteritidis uočeni su klinički znaci bolesti. Titar specifičnih antitela na C. jejuni u serumu inficiranih pilića utvrđen je reakcijom vezivanja komplementa (RVK). Rezultati ispitivanja su ukazali da infekcija salmonelama utiče na imunološki sistem pilića i tako stvara uslove da kampilobakterije naruše zdravstveno stanje domaćina

Discocotyle ohridana n. Sp. (monogenea: Discocotylidae) on the gills of ohrid belvica salmothymus ohridanus (pisces: Salmonidae) from the lake ohrid, macedonia

Discocotyle ohridana n.sp. is described from the gills of Ohrid belvica Salmothymus ohridanus Steindachner, 1892; (syn. Acantholingua ohridana Hadzisce, 1961) from the Lake Ohrid, Macedonia. According our investigation the new species D. ohridana n.sp. differs 56.47% of observed S. ohridanus have been infected and average intensity of infestation is 2.84

Modest protective effects of progesterone treatment in hippocampus of male rats submitted to cerebral hypoperfusion

In the brain, three isoforms of nitric oxide synthase (NOS) regulate production of nitric oxide (NO), a signalling molecule with a role in cerebral blood flow regulation. Depending on the stimulus, NO exerts dual nature, from neuroprotective to neurodestructive. Given the scarcity of literature data on the involvement of nitrosative stress indicators in the rat hippocampal response to 7-day lasting progesterone (P4) treatment following permanent occlusion of both common carotid arteries, we assessed NO level and protein expressions of endothelial nitric oxide synthase (eNOS, including its total (t-eNOS) and phosphorylated at Ser1177 isoform (p-eNOS Ser1177)). According to obtained results, elevated NO levels occurred due to activity of other NOS forms since eNOS expressions were similar between experimental groups. Although NO level was downscaled it was still elevated in occluded animals treated with P4, showing modest anti-nitrosative effect of this potent steroid in the hippocampus