Isolation and identification of antimicrobial peptides derived by peptic cleavage of whey protein isolate

The antimicrobial potential of whey protein isolate hydrolyzed by gastrointestinal enzymes was determined by attempting to identify and characterize the antimicrobial peptides responsible. While tryptic and chymotryptic hydrolysates did not show antibacterial activity, whey proteins hydrolyzed for 45–90 min by pepsin exhibited significant activity. Fractionation of 60-min hydrolysate by reversed-phase high performance liquid chromatography yielded 5 fractions that were antibacterial, with minimum inhibitory concentrations comprised between 20 and 35 μg/mL. These fractions contained short peptides not previously identified as antimicrobial. Fragment 14–18 (KVAGT) of β-lactoglobulin is very close to a sequence previously identified as antibacterial and is found in antimicrobial sequences of diverse origin. Five other peptides derived from β-lactoglobulin, and one fragment from α-lactalbumin (f117–121, KVGIN), were also identified as antibacterial. The identified peptides do not match pepsin action exactly, indicating modified proteolysis of unknown origin. Protein by-products of the dairy industry offer potential for large-scale production of antimicrobial peptides.     

Structural Studies and Valence Band Splitting Parameters in Ordered Vacancy Compound AgGa7Se12

The threefold absorption in the fundamental absorption region of the ternary chalcopyrite AgGa₇Se₁₂, an ordered defect compound of AgGaSe₂, is analyzed to elucidate the three closely spaced band gaps in its valence band due to the lifting of degeneracy of the Γ₁₅ level. Hopfield’s quasi cubic model is employed to extract the crystal-field and spin–orbit splitting parameters and the linear hybridisation of orbitals model for evaluating the percentage contribution of Ag d-orbital and Ga and Se p-orbitals to the p–d hybridization of orbitals. The observed optical properties are correlated with the structural parameters like deformation parameter, anion displacement and anion–cation bond lengths that are deduced from X-ray diffraction data. The compound films for the studies are prepared by a modified form of Gunther’s three temperature technique and the compositional analysis was done by energy dispersive analysis of X-rays. X-ray photoelectron spectroscopy confirms the compound formation while atomic force microscopic technique was used for surface morphological analysis. The electrical resistivity of these n-type semi-conducting films is assessed to be ~5 Ωm and the films are found to be photosensitive.     

Speech and Video Telephony Quality Characterization and Prediction of Live Contemporary Mobile Communication Networks

Quality of Service (QoS) characterization and prediction is of utmost importance in contemporary operating cellular communications networks. Measurements data of speech and video telephony have been collected using modern experimental equipment. More specifically, key performance indicators of radio, speech and video quality are evoked. The objective of our study is to critically investigate the performance of speech and video telephony at live cellular networks correlating significant QoS parameters from radio and the service side. Simple non-linear regression models are also proposed for speech and video quality prediction. Finally, the paper represents the splendid positive influences of the continuous performance evaluation for the optimization of the mobile networks. There are also briefly given guidelines for mobile networks benchmarking.     

Spatial Measurements of Ultrafine Particles Using an Engine Exhaust Particle SizerTM within a Local Community Downwind of a Major International Trade Bridge in Buffalo,New York

Ultrafine particles (UFP) can be defined as having at least one dimension that is less than 100 nanometers. Because of their dimensions, they exhibit unique properties that affect atmospheric transport, exposures, and possibly health endpoints. Freshly generated Diesel particulate matter (DPM) is predominantly in the ultrafine particle size range size range, which in practice is defined by the detection characteristics of the sampling instrument. During two seasons, an Engine Exhaust Particle Sizer^TM (TSI, St. Paul, MN) detects particles over a range of 5.6–560 nm was used to continuously measure real-time particle size distributions along several streets that extend from the Peace Bridge (PB), a major international trade bridge, into a the nearby adjacent neighborhood that has reported a high prevalence rate of asthma (Lwebuga-Mukasa 2000). The Peace Bridge connects Buffalo, NY, USA to Fort Erie, ON, Canada. During summer 2004, one minute average particle number concentrations were continuously monitored along neighborhood streets near the Peace Bridge Complex (PBC) plaza out to about 2 km. Ultrafine particle counts as a function of bridge traffic showed downwind UFP levels at 300 m ranging from 60,000–70,000 p/cm³. Upwind background UFP levels at the shore line of Lake Erie were typically 8,000–10,000 p/cm³ under similar traffic and meteorological conditions. During winter 2006, additional measurements were conducted in front of several homes that were part of a separate indoor-outdoor exposure study (McAuley et al. 2010 McAuley, T. R., Fisher, R., Zhou, X., Jaques, P. A. and Ferro, A. R. 2010. Relationships of Outdoor and Indoor Ultrafine Particles at Residences Downwind of a Major International Border Crossing in Buffalo, NY.. Indoor Air, 20: 298–308. [Crossref] , [Google Scholar]). Sampling at the homes was done during the weekdays when heavy diesel truck traffic was highest. Results showed that most of the UFP number concentrations fell between 10–20 nm in front of homes with UFP levels ranging from 59,000 p/cm³ at couple hundred m downwind to 81,000 p/cm³ several hundred m directly downwind of the Peace Bridge under similar diesel trucks traffic and meteorological conditions.     

Synthesis and nonlinear optical characterization of new poly{2,2′-(3,4-didodecyloxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]}

A new donor–acceptor type poly{2,2′-(3,4-didodecyloxythiophene-2,5-diyl)bis[5-(2-thienyl)-1,3,4-oxadiazole]} (P) was synthesized starting from thiodiglycolic acid and diethyl oxalate through multistep reactions. The polymerization was carried out using chemical polymerization technique. The optical and charge-transporting property of the copolymer was investigated by UV–vis, fluorescence emission spectroscopic and cyclic voltammetric studies. The copolymer shows UV absorption maxima at 375 nm and displays bluish-green fluorescence in DMF solution. Its electrochemical band gap was determined to be 2.07 eV. The nonlinear optical (NLO) properties of the copolymer was investigated at 532 nm using single beam Z-scan and degenerate four-wave mixing (DFWM) techniques with nanosecond laser pulses. The copolymer exhibits strong optical limiting behavior due to effective three-photon absorption (3PA). Values of the effective 3PA coefficient (γ), third-order nonlinear susceptibility (χ⁽³⁾) and figure of merit (F) have been calculated.     

Antibacterial Property of Cold Sprayed Chitosan-Cu/Al Coating

The antibacterial behavior of CS-Cu (chitosan-copper complex) powder and their composite coatings were investigated against Escherichia coli (DH5α). CS-Cu powder and Al (aluminum) based CS-Cu composite powders were synthesized using in-house powder processing techniques. The results indicated that the antibacterial effect of all the powders increased with the proportion of CS-Cu powder. These composite powders were subsequently used as feedstock to generate antibacterial coatings via cold spray technology. The ratios of CS-Cu to Al in their composite powders were 25:75, 50:50, and 75:25 (wt.%). Microstructural characterization and phase analysis of feedstock powders and as-deposited coatings were carried out using FESEM/EDX and FTIR. Antibacterial composite CS-Cu/Al coatings were successfully deposited using cold spraying parameters of 6-8 bars at preheated helium gas, temperature between 140 and 150 °C. The coatings retained the antibacterial properties of the original feedstock powders.     

高性能LCoS虚拟显示器的光学特性

本文叙述一种用于LCoS双瞳虚拟显示器的新型光路结构,它首次达到或超过了pSi(多晶硅)头戴装置的性能36°的视场,801的对比度,无需IPD调节(12mm出射光瞳),并且整个电-光模件的封装配合并不比奥林巴斯EyeTrek和索尼Glasstron的工业标准更复杂.     

Experimental investigation and three-dimensional computational fluid-dynamics modeling of the flash-converting furnace shaft: Part II. Formulation of three-dimensional computational fluid-dynamics model incorporating the particle-cloud description

A fluid-dynamics computer model of the flash-converting furnace shaft, which is based on basic principles, is presented. The model is fully three-dimensional and incorporates the transport of momentum, heat, and mass and the reaction kinetics between the gas and particles in a particle-laden turbulent gas jet. The k-ɛ model was used to describe gas-phase turbulence in an Eulerian framework. The particle-cloud model was used to track the particle phase in a Lagrangian framework. The coupling of gas and particle equations was performed through the source terms in the Eulerian gas-phase governing equations. Copper matte particles were represented as Cu₂S · yFeS _x . Based on experimental observation, the oxidation products were assumed to be Cu₂O, CuO, Fe₃O₄, and SO₂. A reaction mechanism involving the external mass transfer of oxygen from the gas to the particle surface and diffusion of the oxygen through the successive layers of Cu₂O-Fe₃O₄ and CuO-Fe₃O₄ was proposed. The predictions of the computer model were compared with the experimental data collected in a large laboratory furnace. Reasonable agreement between the model predictions and the measurements was obtained in terms of the fractional completion of the oxidation reactions and the sulfur remaining in the reacted particles. The relevance of the computational model for further analysis and optimization of an industrial flash-converting operation is discussed.