Bio-mechanochemical synthesis of silver nanoparticles with antibacterial activity

By using a bio-mechanochemical approach combining mechanochemistry (ball milling) and green synthesis for the first time, silver nanoparticles (Ag NPs) with antibacterial activity were successfully synthesized. Concretely, eggshell membrane (ESM) or Origanum vulgare L. plant (ORE) and silver nitrate were used as environmentally friendly reducing agent and Ag precursor, respectively. The whole synthesis took 30?min in the former and 45?min in the latter case. The photon cross-correlation measurements have shown finer character of the product in the case of milling with Origanum. UV–Vis measurements have shown the formation of spherical NPs in both samples. TEM study has revealed that both samples are composites of nanosized silver nanoparticles homogenously dispersed within the organic matrices. It has shown that the size and size distribution of the silver nanoparticles is smaller and more uniform in the case of eggshell membrane matrix implying lower silver mobility within this matrix. The antibacterial activity was higher for the silver nanoparticles synthesized with co-milling with Origanum plant than in the case of milling with eggshell membrane.     

Behavior of asphaltene and asphaltene fractions films on a Langmuir–Blodgett trough and its relationship with proposed molecular structures

Abstract

Asphaltenes were precipitated from a Venezuelan Ayacucho crude oil and separated into two fractions (A1 and A2) by the p-nitrophenol method. The asphaltenes and the fractions A1 and A2, as well as mixtures of the two fractions were tested in a Langmuir–Bodgett trough. It was found that the asphaltenes and the fraction A2 had similar behavior and higher compressibility than the fraction A1. This is because the molecules of A2 are more flexible than the molecules of A1 as they have aliphatic chains that bond aromatic structures while the A1 has an aromatic nucleus.     

Prebiotic effects of fermentable carbohydrate polymers may be modulated by faecal bulking of non‐fermentable polysaccharides in the large bowel of rats

This study investigated the impact of supplementary fermentable polysaccharides inulin (a prebiotic) and barley β‐glucan on the large bowel, when consumed against a background high or low intake of mixed non‐starch polysaccharide. Rats were fed for 28 days with diets containing high (15%) and low (5%) background dietary fibre (BDF; cellulose plus sugar beet fibre), with or without 5% supplementary fermentable fibre (SFF; inulin or barley β‐glucan). High‐BDF diets unsupplemented with inulin or barley β‐glucan caused greater improvement than supplemented low‐BDF diets in several parameters linked to gut health: they increased colonic Bifidobacterium spp., butyric acid concentration in the caecum, and colonic crypt depth more than inulin and barley β‐glucan. For these parameters, inulin and barley β‐glucan added little to the effects of the high‐BDF diet alone. Furthermore, by allowing for dilution due to the greater faecal bulk induced by the mixed fibre compared with inulin or barley β‐glucan, the total quantity of butyric acid in the colon of BDF‐fed rats was greatly amplified. Interpretation of the effects of prebiotics in diets containing dietary fibre requires concurrent analysis of the multiple effects of non‐fermentable bulk.     

Bacterial growth monitoring in a microfluidic device by confocal reflection microscopy

The feasibility of a method to nondestructively measure planktonic bacterial growth in a microfluidic device was addressed. Here, we report that the growth of Pseudomonas aeruginosa in a microfluidic device could be measured by a three-dimensional image analysis technique based on confocal reflection microscopy in a time-course.     

Effect of the specimen size on strength of Si3N4 + SiC composite

Bending and contact strength of a recently developed carbon derived Si₃N₄ + SiC micro/nanocomposite have been investigated in four-point and opposite sphere modes using specimens with two different sizes of 3 mm × 4 mm × 45 mm and 1 mm × 2 mm × 20 mm. The fracture origins during bending test were clusters of pores and large SiC grains with different size, shape and location, which resulted in relatively low strength (675 MPa and 832 MPa) and Weibull moduli (6.4 and 8.6). The fracture origins in specimens tested in contact mode were cone cracks, originated and arised during the loading, and their similar size and shape, together with the preexisting stress field resulted in high strength (1167 MPa and 1997 MPa) and relative high Weibull moduli (17 and 15). In agreement with the theory, bending test specimens with smaller effective volume exhibited higher strength. In contact test, interaction of cone cracks occured in the small specimens at lower load as in larger one, which resulted in the lower strength of small specimens.     

Using a vulnerability-stress-adaptation framework to predict physical aggression trajectories in newlywed marriage.

The authors used a vulnerability-stress-adaptation framework to examine personality traits and chronic stress as predictors of the developmental course of physical aggression in the early years of marriage. Additionally, personality traits and physical aggression were examined as predictors of the developmental course of chronic stress. Data from 103 couples collected 4 times over the first 3 years of marriage were analyzed with an actor-partner interdependence model and structural equation modeling techniques. Personality traits of husbands predicted their own physical aggression and stress trajectories, as well as their wives' levels of stress and physical aggression. Personality traits of wives predicted their levels of stress and physical aggression and predicted changes in their physical aggression over time. Both husbands' and wives' changes in stress predicted changes in physical aggression over time. Implications for employment of a vulnerability-stress-adaptation model in the study of physical aggression and for improvement of the efficacy of therapies targeting physical aggression in intimate relationships are delineated. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and characterization of polyaniline derivative and silver nanoparticle composites

BACKGROUND: There has been a recent surge of interest in the synthesis and applications of electroactive polymers with incorporated metal nanoparticles. These hybrid systems are expected to display synergistic properties between the conjugated polymers and the metal nanoparticles, making them potential candidates for applications in sensors and electronic devices. RESULTS: Composites of polyaniline derivatives—polyaniline, poly(2,5‐dimethoxyaniline) and poly(aniline‐2,5‐dimethoxyaniline)—and silver nanoparticles were prepared through simultaneous polymerization of aniline derivative and reduction of AgNO₃ in the presence of poly(styrene sulfonic acid) (PSS). We used AgNO₃ as one of the initial components (1) to form the silver nanoparticles and (2) as an oxidizing agent for initiation of the polymerization reaction. UV‐visible spectra of the synthesized nanocomposites reveal the synchronized formation of silver nanoparticles and polymer matrix. The morphology of the silver nanoparticles and degree of their dispersion in the nanocomposites were characterized by transmission electron microscopy. Thermogravimetric analysis and differential scanning calorimetry results indicate an enhancement of the thermal stability of the nanocomposites compared to the pure polymers. The electrical conductivity of the nanocomposites is in the range 10^?4 to 10^?2 S cm^?1. CONCLUSION: A single‐step process for the synthesis of silver nanoparticle–polyaniline derivative nanocomposites doped with PSS has been demonstrated. The approach in which silver nanoparticles are formed simultaneously during the polymerization process results in a good dispersion of the nanoparticles in the conductive polymer matrix. Copyright © 2008 Society of Chemical Industry     

Validity and utility of a multidimensional model of received support in intimate relationships.

The authors of the present study statistically address the largely conceptual debate about the multidimensional nature of received support in intimate relationships. The Support in Intimate Relationships Rating Scale (SIRRS) was factor analyzed in 3 samples of dating and married couples. A novel, 4-factor structure of support types was generated that constituted esteem/emotional, physical comfort, informational, and tangible support types. This structure was reliable and valid in dating and marital relationships, across men and women, and across time. Each support type also demonstrated incremental validity for explaining marital adjustment, depression symptoms, and anxiety symptoms longitudinally. This study is among the first to generate and cross-validate a factor analytically derived set of support types for received support and the first to do so regarding partner support specifically. This is also the first study to replicate a distinct set of support types across different types of intimate relationships, across both sexes, and over time within relationships. Implications for enhancing functional theories of support and for augmenting the construct validity of a multidimensional model of received support are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)