Nonlinear Optical Susceptibilities and Linear Absorption in Phosphorene Nanoribbons: Ab initio study

Using Density Functional Theory (DFT) method we compute linear optical absorption spectra and nonlinear optical susceptibilities of hydrogen passivated armchair and zigzag Phosphorous Nanoribbons (aPNR and zPNR) as well as \alpha-phase phosphorous monolayer. We observe that: (a) Crystallographic direction has a strong effect on the band edge absorption which causes optical anisotropy as well as a red shift of absorption spectra by increasing the nanoribbon width. (b) The absorption values are in the order of $10^{5} cm^{-1}$ which are similar to the experimentally measured values. (c) There is two orders of magnitude enhancement of the 2nd order nonlinear optical susceptibility, $\chi^{(2)}$, in nanoribbons which emanates from breaking the centro-symmetric structure of a monolayer phosphorene by hydrogen surface terminations. (d) Chief among our results is that the 3rd order susceptibility, $\chi^{(3)}$, for phosphorene monolayer and nanoribbons are about $~10^{-13}$ esu ($~10^{-21} \frac{m^{2}}{V^{2}}$) which are in close agreement with experimentally reported values as well as a recently calculated value based on semi-analytic method. This strongly supports reliability of our method in calculating nonlinear optical susceptibilities of phosphorene and in general other nanostructures. Enhanced 2nd order optical nonlinearity in phosphorene promises better second harmonic and frequency difference (THz) generation for photonics applications.Comment: 18 pages, 4 figures, 4 tables, 48 reference

Optical Transitions and Localized Edge States in Skewed Phosphorene Nanoribbons

Using the Tight Binding (TB) parameters extracted from Density Functional Theory (DFT) and Recursive Green's Function method, it is shown that skewed-zigzag black phosphorous (phosphorene) nanoribbons obtain large and tuneable bandgap in response to vertical and transverse electric fields. Depending on the direction of the applied field the mid-gap states could possess the localized or metallic nature i.e. non-zero mid-gap density of states. Adjustability of the bandgap and optical dipole transition matrix elements are explained based on the symmetry of involved band edge states. This promises new electronic and optical devices based on phosphorene nanoribbons.Comment: 21 pages, 12 Figures. newly amended version, June 29, 201

Utjecaj djelomične zamjene šećera sirupom od smokava na preživljavanje bakterije Bacillus coagulans i fizikalno-kemijska svojstva probiotičkog sladoleda

Research background. Various sectors of the food industry demand the enrichment of food with functional compounds. Probiotic products with valuable nutritional and therapeutic properties have attracted great attention in the fields of industry, nutrition and medicine. The aim of the present study is to investigate the sensory and physicochemical properties of probiotic ice cream containing fig syrup and to evaluate the survival of Bacillus coagulans after 90 days of storage at -18 °C. Experimental approach. In this study, four experimental groups of ice cream were produced as follows: plain dairy ice cream (without additives), ice cream containing 109 CFU/g B. coagulans, ice cream containing 25 % fig syrup as sugar substitute and ice cream containing 25 % fig syrup as sugar substitute and 109 CFU/g B. coagulans. They were stored at -18 °C for 3 months. Texture, pH, acidity and viscosity were analysed and microbial counts were determined after 1, 30, 60 and 90 days of storage. The organoleptic evaluation was carried out on days 1 and 90. Results and conclusions. The results showed that during the initial freezing process and the transformation of the mixture into ice cream, the number of B. coagulans decreased from 109 to 107 CFU/g, without significant changes observed over the 90-day period. No significant changes were found in the sensory and textural properties of the samples either. Replacement of 25 % sugar with fig syrup reduced the pH, increased the acidity of the ice cream and improved their viscosity. In conclusion, the production of functional ice cream using fig syrup and B. coagulans is recommended for their health benefits. Novelty and scientific contribution. The results of this study can be used to prepare functional and healthy foods. Our results suggest that fig syrup has the potential to be used as a natural sweetener or sugar substitute in various products.Pozadina istraživanja. U različitim se granama prehrambene industrije pojavila potreba za obogaćivanjem hrane funkcionalnim sastojcima. Probiotički proizvodi s vrijednim hranjivim i terapeutskim svojstvima su od velikog interesa za prehrambenu industriju, nutricionizam i medicinu. Svrha je ovoga rada bila ispitati senzorska i fizikalno-kemijska svojstva probiotičkog sladoleda koji sadržava sirup od smokve, te procijeniti preživljavanje bakterije Bacillus coagulans u dobivenom sladoledu nakon 90 dana skladištenja pri -18 °C. Eksperimentalni pristup. U ovom su istraživanju pripremljene četiri skupine sladoleda, i to: obični mliječni sladoled bez dodataka, sladoled s dodatkom 109 CFU/g bakterije B. coagulans, sladoled s dodatkom 25 % sirupa od smokava kao zamjenom za šećer i sladoled s dodatkom 25 % sirupa od smokava i 109 CFU/g bakterije B. coagulans. Svi su uzorci skladišteni na –18 °C tijekom 3 mjeseca. Ispitani su sljedeći parametri: tekstura, pH-vrijednost, kiselost i viskoznost dobivenih sladoleda, a broj je mikroorganizama određivan nakon 1, 30, 60 i 90 dana skladištenja. Organoleptičko ispitivanje je provedeno tijekom prvog i devedesetog dana skladištenja. Rezultati i zaključci. Rezultati pokazuju da se tijekom prve faze zamrzavanja smjese i nastanka sladoleda broj bakterija B. coagulans smanjio s 109 na 107 CFU/g, te se nakon toga nije mijenjao tijekom 90 dana skladištenja. Također nisu uočene bitne promjene senzorskih svojstava niti teksture uzoraka. Zamjenom 25 % šećera sirupom od smokava smanjila se pH-vrijednost, a povećala kiselost te poboljšala viskoznost sladoleda. Zaključno, možemo preporučiti proizvodnju funkcionalnog sladoleda s dodatkom sirupa od smokve i bakterijom B. coagulans zbog njihovog pozitivnog učinka na zdravlje. Novina i znanstveni doprinos. Dobiveni rezultati mogu se primijeniti u pripremi funkcionalne i zdrave hrane. Naši rezultati pokazuju da bi se sirup od smokava mogao koristiti kao prirodni zaslađivač ili zamjena za šećer u različitim proizvodima

The effects of Zataria multiflora on inhibition of polyphenoloxidase and melanosis formation in shrimp (Litopenaeus vannamei)

Shrimp melanosis (black spot) is an important surface discoloration caused by polyphenol oxidase (tyrosinase) enzyme, which oxidizes phenols and leads to insoluble black pigments, the melanins. Sulphiting agents are widely used as melanosis inhibitors; but, the hazards related to sulphated foods, such as allergic reactions and severe disorders in asthmatic patients have created a necessity to find the effective natural alternatives. The current study was accomplished to assay the in vitro antityrosinase effect of Z. multiflora EO as well as its capability to retard the melanosis formation in shrimp during iced storage. According to GC/MS results, carvacrol, thymol and p-cymene were the major components of Z.multiflora EO, representing 50.8, 14.4 and 10.6, respectively. DPPH radical scavenging activity of EO was 0.8±0.02 mg/ml and 63.2% of tyrosinase activity decreased when EO with a concentration of 0.25% was applied. Furthermore, it has been observed that immersing the shrimps in 1% EO aqueous suspension retarded the melanosis formation in shrimp during 10 days of iced storage. It can be concluded that Z. multiflora EO could be used as an effective natural processing aid to increase the shrimp shelf-life during iced storage

PERSIA: manuel utilisateur

PERSIA (Phase-based Estimation for Registration and Sub-pixel Image Alignment) est un algorithme qui permet d'effectuer une mise en correspondance sous-pixélique des images. La méthode est basée sur la corrélation de phase et dispose d'une robustesse remarquable aux variations d'éclairage

Lactation protects against myocardial ischemia-reperfusion injury in rats

Some researchers have reported that lactation is effective in reducing cardiovascular disease risk factors. The purpose of this study was to investigate whether lactation may improve intrinsic tolerance against ischemia reperfusion (IR) injury. The rats were randomly divided into two groups (n = 8 in each group). In the lactation (Lact) group, the surgery was performed on postpartum day 21 (at the end of lactation period) and the results were compared with those of virgin female rats (control group). Cardiac IR injury was induced by means of left anterior descending coronary artery occlusion for 30 min followed by reperfusion for 120 min. Infarct size was measured using the staining agent 2,3,5-triphenyltetrazolium chloride. At the end of the experiment, Mean arterial pressure in the control group was significantly lower than that in the Lact group. Myocardial infarct size was significantly reduced in the Lact group (23 ± 3% vs. 45 ± 8%, p < 0.05 in the control group). Lactation reduced the extent of myocardial injury induced by ischemia and reperfusion. So, lactation may increase cardiac tolerance to ischemic injury

Optimization of leavening agents in extruded gluten-free brewer's rice hard pretzel using response surface methodology

Celiac is the second most important issue in food sensitivities. The only treatment for celiac is a lifetime avoidance of consuming gluten. As pretzels are one of the most popular snacks in the world, making gluten-free pretzels is a market need. To produce gluten-free products, it is important to optimize the ingredients of the formulation. This research focused on optimization of the leavening agents of the most popular commercial hard pretzel formulation in which wheat flour is replaced with brewer's rice flour. This research also attempts to explain the effect of leavening agents in products containing no matrix molecules such as gluten. Response surface methodology via the central composite design was used to optimize the effects of yeast and bicarbonate of soda on the hardness (cutting strength), fracturability (brittleness), surface color, lateral expansion, expansion ratio, specific length, density (bulk, particle, material), porosity (open, close, total), water absorption index, water solubility index, water holding capacity, oil absorption index and oil holding capacity of gluten-free hard pretzel. The optimized results indicated that the gluten-free pretzel requires 8.05g yeast and 2.59g bicarbonate of soda for every 500g of brewer's rice flour

SURPRISE: manuel utilisateur

SUper-résolution de la Radiométrie et de la Photométrie des Images Satellitaires Entrelacées) est un algorithme qui permet de reconstruire une image à haute résolution à partir d'une séquence d'images aériennes ou satellitaires. Cette algorithme exploite les décalages sous-pixéliques entre les images d'une séquence pour augmenter la densité d'échantillonnage. Autrement dit, il permet d'échanger la résolution temporelle d'une séquence d'image contre une résolution spatiale plus importante