The synthesis,activation and characterization of charcoal powder for the removal of methylene blue and cadmium from wastewater

Charcoal prepared from biomass, wastes of the local forest (tree branches), activated with NaOH solution and with Degussa P25 (TiO₂) was used as adsorbent and photocatalyst for the removal of cadmium cations and methylene blue from wastewater. These materials were characterized by using atomic force microscopy for roughness surface. The energy dispersive X-ray (EDX) spectroscopy and X-ray diffraction (XRD) analysis indicate the existence of nano TiO₂ on the charcoal surface. Additionally, the FT-IR spectroscopy measurements indicate that the alkali treatment develops hydroxyl groups on charcoal surface which could adsorb methylene blue, heavy metals and other pollutants via the synergistic effect. The activities of the charcoal (BC), activated charcoal (BCA) and BCA/TiO₂ mixture (BCA-D) depend on the contact time, adsorbent dosage and pH. The adsorption kinetic data were tested using pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The kinetic studies showed that the adsorption is followed by the pseudo-second-order reaction with regard to the intraparticle diffusion rate kinetics.     

Double crosslinked chitosan and gelatin submicronic capsules entrapping aminoacid derivatives with potential antitumoral activity

The aim of the article was the synthesis of novel l-phenylalanine derivatives with biological activity and their immobilization into polymeric particles. Thus, new formyl, acetyl and p-methoxy derivatives of l-phenylalanine with antitumor activity were synthesized by reaction with p-nitrobenzoyl chloride, followed by the reduction of nitro group and acylation of the new formed amino group. The chemical structures of the obtained aminoacid derivatives were determined by FT-IR, NMR, MS and elemental analyses. The compounds were encapsulated into chitosan- and gelatin-based submicronic capsules, prepared by double crosslinking (ionic and covalent) in a O/W/O double emulsion. The varying parameter polymer/ionic crosslinker molar ratio was seen to influence particle size, morphology, swelling degree, thermal properties, as well as their capacity to incorporate and release the new active principles. The in vivo acute toxicity and antitumoral effect of aminoacid derivatives in free form or encapsulated were evaluated on rats. Drug encapsulation into polymeric systems was proven to enhance antitumoral activity against implanted Guerin’s carcinoma.     

Optimization of synthesis parameters in interfacial polycondensation using design of experiments

The reaction of phenylphosphonic dichloride with 4,4′-cyclohexylidenebisphenol by a gas–liquid interfacial polycondensation was investigated. The design of experiments (DoE) method is used for determination of the best reaction conditions. The correlation of simultaneous influence of the parameters (reaction time, reaction temperature, alkaline medium, reagents molar ratio) on yield and inherent viscosity was studied.     

Nanostructured chitosan–surfactant matrices as polyphenols nanocapsules template with zero order release kinetics

Nanostructured membranes and films of cationic surfactant–chitosan with tannic acid as polyphenol model were obtained by phase inversion method. The membranes were investigated by Attenuated Total Reflectance Fourier Transform InfraRred, X-Ray Diffraction, Scanning Electron Microscopy and Thermogravimetry, and the films topography was analysed by Atomic Force Microscopy. The analysis reveals that the interactions at the molecular level between cationic CTAB surfactant and cationic chitosan polymer strive to weaken membrane stability, whereas, the tannic acid is favoured to cluster with CTAB and diminish the membrane thermodynamic instability. The nanocapsules formed, with dimensions in the range of 16.35–27.68 nm, are congregating in clusters having dimensions in the domain of 50–300 nm. The layers resulted from these nanostructures arrangement constitute a surfactant–chitosan matrix with tannic acid suitable for drug controlled release with zero order kinetics.     

Psychosocial mediators of racial differences in nighttime blood pressure dipping among normotensive adults.

Shallow declines in nocturnal compared with diurnal blood pressure (BP dipping) have been associated with cardiovascular disease. In U.S. samples, Blacks demonstrate less BP dipping compared with Whites. In a sample of 60 Black and 60 White normotensive adults we examined stress, social integration (including parental status), social support, and hostility as potential mediators of the association between race and BP dipping. The effect of race on diastolic BP dipping was partially mediated by parental status. The effect of race on heart rate dipping was partially mediated by stressful life events. No psychosocial factors mediated the relation between race and systolic BP dipping. Although psychosocial factors appear to account for some of the observed racial differences in nocturnal blood pressure decline, our data suggest that these differences cannot be attributed entirely to covarying psychosocial effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acrylic hydrogels‐based biocomposites: Synthesis and characterization

Hydrogels based on polyacrylic and polymethacrylic acids were synthesized using two variants of redox initiating systems and three crosslinking agents in various ratios to the monomer. The chemical structure of these hydrogels was extensively studied by Fourier transform infrared (FTIR) spectrometry and Raman spectrometry. These hydrogels were also characterized by other techniques, namely thermo gravimetric analysis (TGA), differential thermal gravimetry, differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). The hydrogel ability to immobilize enzymes through covalent bonds was studied by FTIR and Raman spectrometry and by analyzing the SEM images before and after enzyme immobilization. The enzyme influence on the thermal behavior of the hydrogel biocomposite was investigated by DSC and TGA, too. The methacrylic acid leads to more thermo stable hydrogels formation than acrylic acid. Acrylic and methacrylic hydrogels are able to covalently immobilize enzymes. This is proved by the important changes which occur in the chemical composition, the thermal behavior and the morphology of hydrogels after immobilization stage. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Iron Powder Treated Gray Irons: Critical Shape Characteristics for Graphite Nuclei

A program was conducted to research how to characterize the size and shape of micro-particles. These can act as graphite nuclei, but are altered by adding a commercial iron powder, or after a similar treatment combined with inoculation. Resin sand mold (RSM) and metal mold (MM) solidified sample structures were subjected to automatic image analysis. In general, a higher cooling rate, typical for MM solidification, favors smaller size and more compact particles, even in RSM media. Iron powder treatment led to the largest particles with unusual morphologies, better defined by complex shape factors, which employ actual perimeters, rather than the simpler median size and aspect ratio method. Conventional inoculation employed after an iron powder treatment altered the particles (smaller and more compact), which benefited their effectiveness to act as graphite nuclei, especially at slower solidification rates in RSMs. The results confirm that promoting more compact micro-inclusions, at smaller sizes, involved in graphite nucleation, reduces the sensitivity to chill and improves the eutectic cell characteristics in gray cast iron.