Preparation and characterization of nano and micro particles of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) via emulsification/solvent evaporation and nanoprecipitation techniques

This paper describes the preparation and the characterization of micro and nanoparticles of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) via two different preparation techniques. The first technique is the emulsification/solvent evaporation while the second is the nanoprecipitation which is being reported for first time for the PHBV particles. The effect of various conditions of preparation on the size and the morphology of the produced particles was studied for both techniques. Field emission scanning electron microscopy, static light scattering and dynamic light scattering were used to analyse the size and the morphology of the particles. The particles produced using the emulsification/solvent evaporation were spherical porous micro and nanoparticles ranging from 300 up to 20 μm. The size, porosity and the particle size distribution were found to be controllable basically via choosing the surfactant and the polymer concentration when the emulsification technique was used. Choosing the appropriate anti-solvent and adjusting its polarity are crucial for getting spherical particles via nanoprecipitation. The micro and nanoparticles produced via both techniques are intended basically to be used for reinforcing biopolymeric matrices of PHBV and starches.     

Thermodynamic Stability,Half-Metallic and Optical Properties of Sc2CoSi [001] Film:a DFT Study

The electronic and optical characteristics of the Sc2 CoSi Heusler with L21 structure and also the surface effect on electronic and optical properties, and the ?lms thermodynamic stability of the [001] direction in four cases including:Sc-Sc, Sc-Co, Sc-Si and Co-Si terminations are studied using the ?rst principles calculations(FPLAPW) within the framework of the density functional theory(DFT). The band structure calculations represent the ferromagnetic halfmetallic properties with 100% spin polarization and 0.54 e V indirect gap in spin down for Sc2 CoSi bulk with optimized lattice parameters of 6.25 A?. The total magnetic moment obtained for this compound is-1.0 μB, which is in accordance with Slater-Pauling rule. The half-metallic(HM) behavior by 100% spin polarization at Fermi level is occurred in the Sc-Si termination with a 0.32 eV gap in down spin. The optical responses have been calculated for the bulk and ScSi termination by a red shift in these parameters and the metallic treatments have been increased. According to the thermodynamic phase diagrams, it is shown the Sc-Si and Sc-Sc terminations are more stable than other terminations.     

Phytochemistry,Ethnopharmacological Uses,Biological Activities,and Therapeutic Applications of Cassia obtusifolia L.: A Comprehensive Review

Cassia obtusifolia L., of the Leguminosae family, is used as a diuretic, laxative, tonic, purgative, and natural remedy for treating headache, dizziness, constipation, tophobia, and lacrimation and for improving eyesight. It is commonly used in tea in Korea. Various anthraquinone derivatives make up its main chemical constituents: emodin, chrysophanol, physcion, obtusifolin, obtusin, au rantio-obtusin, chryso-obtusin, alaternin, questin, aloe-emodin, gluco-aurantio-obtusin, gluco-obtusifolin, naphthopyrone glycosides, toralactone-9-β-gentiobioside, toralactone gentiobioside, and cassiaside. C. obtusifolia L. possesses a wide range of pharmacological properties (e.g., antidiabetic, antimicrobial, anti-inflammatory, hepatoprotective, and neuroprotective properties) and may be used to treat Alzheimer’s disease, Parkinson’s disease, and cancer. In addition, C. obtusifolia L. contributes to histamine release and antiplatelet aggregation. This review summarizes the botanical, phytochemical, and pharmacological features of C. obtusifolia and its therapeutic uses.     

Error control for multimedia communications in wireless sensor networks: A comparative performance analysis

The emerging multimedia applications of Wireless Sensor Network (WSNs) impose new challenges in design of algorithms and communication protocols for such networks. In the view of these challenges, error control is an important mechanism that enables us to provide robust multimedia communication and maintain Quality of Service (QoS). Despite the existence of some good research works on error control analysis in WSNs, none of them provides a thorough study of error control schemes for multimedia delivery. In this paper, a comprehensive performance evaluation of Automatic Repeat Request (ARQ), Forward Error Correction (FEC), Erasure Coding (EC), link-layer hybrid FEC/ARQ, and cross-layer hybrid error control schemes over Wireless Multimedia Sensor Network (WMSNs) is performed. Performance metrics such as energy efficiency, frame Peak Signal-to-Noise Ratio (PSNR), frame loss rate, cumulative jitter, and delay-constrained PSNR are investigated. The results of our analysis show how wireless channel errors can affect the performance of multimedia sensor networks and how different error control scenarios can be effective for those networks. The results also provide the required insights for efficient design of error control protocols in multimedia communications over WSNs.     

On a Special Generalized Mixture Class of Probabilistic Models

In this paper, we develop a new mathematical strategy to create flexible lifetime distributions. This strategy is based on a special general-ized mixture derived to the one involved in the so-called weighted exponential distribution. Thus, we introduce a new class of lifetime distributions called "special generalized mixture" class and discussed its qualities. In particular, a short list of new lifetime distributions is presented in details, with a focus on the one based on the Lomax distribution. Different mathematical proper-ties are described, including distributional results, diverse moments measures, incomplete moments, characteristic function and bivariate extensions. Then, the applicability of the new class is investigated through the model parameters based on the Lomax distribution and the analysis of a practical data set.