Structure of nanoparticles embedded in micellar polycrystals

We investigate by scattering techniques the structure of water-based soft composite materials comprising a crystal made of Pluronic block-copolymer micelles arranged in a face-centered cubic lattice and a small amount (at most 2% by volume) of silica nanoparticles, of size comparable to that of the micelles. The copolymer is thermosensitive: it is hydrophilic and fully dissolved in water at low temperature (T ~ 0{\deg}C), and self-assembles into micelles at room temperature, where the block-copolymer is amphiphilic. We use contrast matching small-angle neuron scattering experiments to probe independently the structure of the nanoparticles and that of the polymer. We find that the nanoparticles do not perturb the crystalline order. In addition, a structure peak is measured for the silica nanoparticles dispersed in the polycrystalline samples. This implies that the samples are spatially heterogeneous and comprise, without macroscopic phase separation, silica-poor and silica-rich regions. We show that the nanoparticle concentration in the silica-rich regions is about tenfold the average concentration. These regions are grain boundaries between crystallites, where nanoparticles concentrate, as shown by static light scattering and by light microscopy imaging of the samples. We show that the temperature rate at which the sample is prepared strongly influence the segregation of the nanoparticles in the grain-boundaries.Comment: accepted for publication in Langmui

Quantitative description of temperature induced self-aggregation thermograms determined by differential scanning calorimetry

A novel thermodynamic approach for the description of differential scanning calorimetry (DSC) experiments on self-aggregating systems is derived and presented. The method is based on a mass action model where temperature dependence of aggregation numbers is considered. The validity of the model was confirmed by describing the aggregation behavior of poly(ethylene oxide)-poly(propylene oxide) block copolymers, which are well-known to exhibit a strong temperature dependence. The quantitative description of the thermograms could be performed without any discrepancy between calorimetric and van 't Hoff enthalpies, and moreover, the aggregation numbers obtained from the best fit of the DSC experiments are in good agreement with those obtained by light scattering experiments corroborating the assumptions done in the derivation of the new model

Identification of Escherichia coli strains from water vending machines of Kelantan, Malaysia using 16S rRNA gene sequence analysis

Water vending machines provide an alternative source of clean and safe drinking water to the consumers. However, the quality of drinking water may alter due to contamination from lack of hygienic practices and maintenance of the machines. Hence, this study was conducted to determine the microbiological quality of water from vending machines and associated contact surfaces. Seventeen water samples and 85 swab samples (nozzles, drip trays, coin slots, buttons and doors) from 3 locations in Kelantan were collected. Polymerase chain reaction amplification and 16S ribosomal ribonucleic acid (rRNA) sequencing were carried out and sequences obtained were compared against the sequences available in the National Centre for Biotechnology Information database using the basic local alignment search tool programme. Coliform counts were observed in 94.12 % of water samples, 76.47 % of nozzles and 82.35 % of drip tray swabs. Furthermore, results of 16S rRNA sequence analysis indicated that two gram-negative isolates were identified as Escherichia coli U 5/41 (Accession no. NR_024570.1) and E. coli O157:H7 EDL933 (Accession no. CP008957.1) with similarity value of 100 %, respectively. The results from this study further improve our understanding of the potential microorganisms in drinking water. Regular maintenance and cleaning of water vending machines are important to reduce bacterial growth and the presence of waterborne pathogens

Self-compacting concrete blended with fly ash and ground granulated blast furnace slag

This research study was performed on the self-compacting concrete (SCC) mixture blended with 5%, 10%, 15%, and 20% of fly ash (FA) and 5%, 10%, 15%, and 20% of ground granulated blast furnace slag (GGBFS) individually and with a combination of FA and GGBFS, that is, 5% (2.5% FA and 2.5% GGBFS), 10% (5% FA and 5% GGBFS), 15% (7.5% FA and 7.5% GGBFS), and 20% (10% FA and 10% GGBFS) by the weight of Portland cement. The main theme of this research work is to determine the fresh properties in terms of filling ability (slump flow, V�Funnel and T50 flow), passing ability (J-Ring and L-box), and sieve segregation test of SCC mixture and hardened properties in terms of compressive, split tensile, and flexural strengths and permeability of SCC mixture. However, the concrete specimens were prepared at 0.40 water– cement ratio, and these specimens were tested at 28 and 90 days. The results showed that the fresh properties of SCC mixture blended with FA and GGBFS provide better results with addition of a superplasticizer and hardened properties of SCC mixture are enhanced while utilizing 5% of GGBFS and 5% of FA by the weight of PC at 28 and 90 days, respectively

Beaver Research in the Uvs Nuur Region

In 1985, 1988, and 2002 Castor fiber birulai was introduced to the Tes Gol of the Uvs Nuur basin in North-western Mongolia. The beavers migrated through the Republic of Tyva and settled in the middle part of Tes Gol near the Tyvinian-Mongolian border. About 10 colonies were recorded in this region in 2002. Strict protection of Castor fiber birulai has to be ensured in Mongolia and the Republic of Tyva in future

In Memoriam, Academician Prof. Dr. Osor Shagdarsuren (1929-2010)

Academician, Professor Osor Shagdarsuren passed away due to apoplexy on Tuesday, February 2, 2010, at the age of 81. He was one of the most respected Mongolian ornithologists, biologists, and educators. The Mongolian scientific community has lost one of its greatest members, the premier Mongolian ornithologist

Q methodology and rural research

Traditionally, rural scholarship has been limited in its methodological approach. This has begun to change in recent years as rural researchers have embraced a range of different methodological tools. The aim of this article is to contribute to greater methodological pluralism in rural sociology by introducing readers to a method of research that is rarely engaged in the field, that is, Q methodology. The article describes the defining features of the approach as well as providing examples of its application to argue that it is a method that offers particular opportunities and synergies for rural social science research