Cultivation and characterization of pterygium as an ex vivo study model for disease and therapy

Purpose

Development of ex vivo model to study pathogenesis, inflammation and treatment modalities for pterygium.

Outage Analysis of LTE-A Femtocell Networks with Nakagami-m Channels

The concept of extending traditional macrocell cellular structure with small cells (like femtocells) in next-generation mobile networks (e. g., Long Term Evolution Advanced) provides a great opportunity to improve coverage and enhance data rate. Femtocells are cost efficient, indoor base stations. These femtocells can operate in closed mode i. e. only restricted users connection are allowed. Therefore, if the number of deployed femtocells is significant, that can dramatically modify the interference pattern of a macrocell. Thus mobile service providers have to pay attention for the number of simultaneously operating femtocells and encroach, if necessary, to provide appropriate service level to every mobile user. In this paper we provide an analytic framework to characterize the upper bound of service outage probability for a potential macrocell user in a two-tier mobile system, when the radio channels are infected by Nakagami- \(m\) fading. In our proposal the femtocells are operating in closed mode and deployed into a designated macrocell, hence every femtocell increases the interference level. The spatial location femtocells is modelled with Poisson cluster process. Compared to traditional grid structure or completely spatial random Poisson point process femtocell deployment, cluster based layout may provides more life realistic deployment scenario. To evaluate the upper bound of service outage we use the tools of stochastic geometry.     

A Simple Environmentally-friendly Method for the Selective Synthesis of 1,5-benzodiazepine Derivatives using Zeolite Catalyst

The modified small pore size zeolite E4a has been found to be an efficient catalyst for the regioselective synthesis of 2,3-dihydro-1H-1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, cheap, environmentally-friendly and give the benzodiazepines in high yield.     

CS2 Poisoning of Size-Selective Cubooctahedral Pd Particles in Styrene Hydrogenation

Copper, manganese and iron phthalocyanines were found to be highly efficient catalysts for cyclopropanation of olefins using ethyldiazoacetate as carbene precursor. In general copper(II)-phthalocyanine was found to be the most active catalyst followed by the Mn(II)Pc and Fe(II)Pc. Ni(II)Pc and Co(II)Pc were found to be the less active catalysts for this reactions.     

Heterogeneous Catalytic Solvent-free Synthesis of Quinoline Derivatives via the Friedländer Reaction

A simple solvent-free heterogeneous catalytic method was developed for the synthesis of substituted quinoline derivatives via the Friedländer cyclization.     

Variation in Chemical Defense Among Natural Populations of Common Toad, <Emphasis Type="Italic">Bufo bufo</Emphasis>, Tadpoles: the Role of Environmental Factors

Defensive toxins are widespread in nature, yet we know little about how various environmental factors shape the evolution of chemical defense, especially in vertebrates. In this study we investigated the natural variation in the amount and composition of bufadienolide toxins, and the relative importance of ecological factors in predicting that variation, in larvae of the common toad, Bufo bufo, an amphibian that produces toxins de novo. We found that tadpoles’ toxin content varied markedly among populations, and the number of compounds per tadpole also differed between two geographical regions. The most consistent predictor of toxicity was the strength of competition, indicating that tadpoles produced more compounds and larger amounts of toxins when coexisting with more competitors. Additionally, tadpoles tended to contain larger concentrations of bufadienolides in ponds that were less prone to desiccation, suggesting that the costs of toxin production can only be afforded by tadpoles that do not need to drastically speed up their development. Interestingly, this trade-off was not alleviated by higher food abundance, as periphyton biomass had negligible effect on chemical defense. Even more surprisingly, we found no evidence that higher predation risk enhances chemical defenses, suggesting that low predictability of predation risk and high mortality cost of low toxicity might select for constitutive expression of chemical defense irrespective of the actual level of predation risk. Our findings highlight that the variation in chemical defense may be influenced by environmental heterogeneity in both the need for, and constraints on, toxicity as predicted by optimal defense theory.     

Light-harvesting bio-nanomaterial using porous silicon and photosynthetic reaction center

ABSTRACT: Porous silicon microcavity (PSiMc) structures were used to immobilize the photosynthetic reaction center (RC) purified from the purple bacterium Rhodobacter sphaeroides R-26. Two different binding methods were compared by specular reflectance measurements. Structural characterization of PSiMc was performed by scanning electron microscopy and atomic force microscopy. The activity of the immobilized RC was checked by measuring the visible absorption spectra of the externally added electron donor, mammalian cytochrome c. PSi/RC complex was found to oxidize the cytochrome c after every saturating Xe flash, indicating the accessibility of specific surface binding sites on the immobilized RC, for the external electron donor. This new type of bio-nanomaterial is considered as an excellent model for new generation applications of silicon-based electronics and biological redox systems.     

Sensory Evaluation and Electronic Tongue for Sensing Flavored Mineral Water Taste Attributes

In this article a trained sensory panel evaluated 6 flavored mineral water samples. The samples consisted of 3 different brands, each with 2 flavors (pear‐lemon grass and josta berry). The applied sensory method was profile analysis. Our aim was to analyze the sensory profiles and to investigate the similarities between the sensitivity of the trained human panel and an electronic tongue device. Another objective was to demonstrate the possibilities for the prediction of sensory attributes from electronic tongue measurements using a multivariate statistical method (Partial Least Squares regression [PLS]). The results showed that the products manufactured under different brand name but with the same aromas had very similar sensory profiles. The panel performance evaluation showed that it is appropriate (discrimination ability, repeatability, and panel consensus) to compare the panel's results with the results of the electronic tongue. The samples can be discriminated by the electronic tongue and an accurate classification model can be built. Principal Component Analysis BiPlot diagrams showed that Brand A and B were similar because the manufacturers use the same aroma brands for their products. It can be concluded that Brand C was quite different compared to the other samples independently of the aroma content. Based on the electronic tongue results good prediction models can be obtained with high correlation coefficient (r² > 0.81) and low prediction error (RMSEP < 13.71 on the scale of the sensory evaluation from 0 to 100).     

FE Macro/Micro Models for Contact Temperature Prediction at Steel/Composite Interfaces

Finite element (FE) contact and thermal macro/micro models have been developed to study the real thermal behavior of a fiber/matrix microstructure under sliding motion of a steel asperity. At first the contact parameters were evaluated using an approximate contact technique, followed by a transient thermal FE evaluation. The latter considers the heat partition between the steel asperity and the real fiber/matrix microenvironment of a normally oriented carbon fiber/polyether ether ketone composite. The temperature results obtained were compared with those representing a macroscopic approach.     

The effect of graphene nanoplatelet thickness on the fracture toughness of Si3N4 composites

Si₃N₄ composites with 3 and 5?wt% of graphene nanoplatelet (GNP) additions were prepared by spark plasma sintering. We used both commercially available GNPs and thinner few-layer graphene nanoplatelets (FL-GNPs) prepared by further exfoliation through ball milling with melamine addition. We found that by employing thinner FL-GNPs as filler material a 100% increase in the fracture toughness of Si₃N₄/3?wt% FL-GNP composites (10.5?±?0.2?MPa?m^1/2) can be achieved as compared to the monolithic Si₃N₄ samples (5.1?±?0.3?MPa?m^1/2), and 60% increase compared to conventional Si₃N₄/3?wt% GNP composites (6.6?±?0.4?MPa?m^1/2). For 5?wt% filler content the increase of the fracture toughness was near 50% for both GNP and FL-GNP fillers. The hardness of the composites decreased with increasing GNP content. However, composites reinforced with 5?wt% of FL-GNPs displayed 30% higher Vickers hardness (12.8?±?0.2?GPa) than their counterparts comprising conventional GNP fillers (9.8?±?0.2?GPa). We attribute the enhanced mechanical properties obtained with thinner FL-GNPs to their higher aspect ratio leading to a more homogeneous dispersion, higher interface area, as well as smaller pores in the ceramic matrix.