Cementation in a matrix of loose sandy soil using biological treatment method

Man-made materials varying from cement-based to chemical-based have been injected into soils to improve their engineering properties (shear strength, compressibility, permeability, bearing capacity etc.). Soil type in general plays important role in determination of treatment material and method. Materials used for soil treatment might have side effects in terms of air pollution, soil or water contamination etc. during manufacturing or application. An alternative, environmentally friendly soil treatment method that is based on the use of bacteria present in soils and named Biological Treatment Method (BTM) has been used by researchers to bond particles of loose sandy soils via creation of calcite (CaCO3) generated by bacteria using urea to influence the precipitation of calcium carbonate. This study presents the results of bacterial induced cementation (BIC) in matrix of loose sandy soil. A bacterium used in this study is Sporosarcina pasteurii that is naturally present in soils and is aerobic type. The bacteria grown in laboratory environment were injected to the matrix of loose sandy soil. Subsequent nutrient mediums were introduced to specimens to accelerate the development of cementation level. Number of bacteria, pH level, temperature and amount of CaCO3 were measured during the duration of testing. Images of Scanning Electron Microscope (SEM) showed that creation of cementation from precipitation of CaCO3 on the surface and pores of soil matrix were observed for only sand samples into which nutrient was flushed on sequence of arbitrary time.Key words: Biological treatment, sand, soil treatment

Business as usual? The role of BRICS co- operation in addressing health system priorities in East and Southern Africa

There has been increased interest in whether “South-­‐South” co-­‐operation by Brazil, Russia, India, China and South Africa (BRICS) advances more equitable initiatives for global health. This article examines the extent to which resolutions, commitments, agreements and strategies from BRICS and Brazil, India and China (BIC) address regionally articulated policy concerns for health systems in East and Southern Africa (ESA) within areas of resource mobilization, research and development and local production of medicines, and training and retention of health workers. The study reviewed published literature and implemented a content analysis on these areas in official BRICS and ESA regional policy documents between 2007 and 2014. The study found encouraging signals of shared policy values and mutuality of interest, especially on medicines access, although with less evidence of operational commitments and potential divergence of interest on how to achieve shared goals. The findings indicate that African interests on health systems are being integrated into south-­‐south BRICS and BIC platforms. It also signals, however, that ESA countries need to proactively ensure that these partnerships are true to normative aims of mutual benefit, operationalize investments and programs to translate policy commitments into practice and strengthen accountability around their implementation

Alien species on the coasts of Turkey

The compilation of data on alien species reported from the Turkish coasts yielded a total of 263 species belonging to 11 systematic groups, of which Mollusca had the highest number of species (85 species), followed by Crustacea (51), fishes (43) and phytobenthos (39). The Black Sea is represented by a total of 20 alien species, the Sea of Marmara by 48 species, the Aegean Sea by 98 species and the Levantine Sea by 202 species. The majority of aliens found in the Black Sea and the Sea of Marmara were transported via shipping, whereas the Levantine coast is extensively subjected to Lessepsian migration. Benthic habitats (soft and hard substrata) comprise 76% of the total alien species and the pelagic environment is inhabited by thirty-nine species. Almost 50% of aliens collected from the Turkish coasts were found only at 0-10 m depth. Eight species occur at depths deeper than 100 m. The impacts of aliens on the benthic and pelagic ecosystems are presented

The validity of eight neoclassical facial canons in the Turkish adults

The neoclassical canons were used to define the proportions between various areas of the head and face. Therefore, this study was done to establish the neoclassical canons of facial proportions in Turkish adults. A total of 200 healthy adults 20 to 35 years of age were examined. Using anthropometric landmarks, 5 horizontal and 9 vertical direct measurements were made on the faces with a sliding calliper. Results have been compared with 8 neoclassical facial canons. When comparing between sexes, a significant difference has been found in all measurements except the upper facial width, left eye-fissure width, forehead height I and II (p < 0.005). The nasofacial proportion has been found to include the most proportional subjects (33%) followed by the orbito-nasal (30%), the orbital proportion (25%) and the naso-oral proportion (17%) in the female. Considering the male, the orbital proportion has been found to include the most proportional subjects (23%) followed by the orbito-nasal proportion (21%), naso-facial proportion (19%) and the naso-oral proportion (17%). The neoclassical canons have been shown to rarely be applicable to Turkish adults and our results may contribute to determine the concepts of transcultural facial structures

Structural, Vibrational and Electronic Properties of Single Layer Hexagonal Crystals of Groups IV and V

Using first-principles density functional theory calculations, we investigate a family of stable two-dimensional crystals with chemical formula $A_2B_2$, where $A$ and $B$ belong to groups IV and V, respectively ($A$ = C, Si, Ge, Sn, Pb; $B$ = N, P, As, Sb, Bi). Two structural symmetries of hexagonal lattices $P\bar{6}m2$ and $P\bar{3}m1$ are shown to be dynamically stable, named as $\alpha$- and $\beta$-phases correspondingly. Both phases have similar cohesive energies, and the $\alpha$-phase is found to be energetically favorable for structures except CP, CAs, CSb and CBi, for which the $\beta$-phase is favored. The effects of spin-orbit coupling and Hartree-Fock corrections to exchange-correlation are included to elucidate the electronic structures. All structures are semiconductors except CBi and PbN, which have metallic character. SiBi, GeBi and SnBi have direct band gaps, whereas the remaining semiconductor structures have indirect band gaps. All structures have quartic dispersion in their valence bands, some of which make the valence band maximum and resemble a Mexican hat shape. SnAs and PbAs have purely quartic valence band edges, i.e. $E{\sim}{-}\alpha k^4$, a property reported for the first time. The predicted materials are candidates for a variety of applications. Owing to their wide band gaps, CP, SiN, SiP, SiAs, GeN, GeP can find their applications in optoelectronics. The relative band positions qualify a number of the structures as suitable for water splitting, where CN and SiAs are favorable at all pH values. Structures with quartic band edges are expected to be efficient for thermoelectric applications

Global behavior of the difference equation x n+1 =

abstract: The aim of this work is to investigate the global stability, periodic nature, oscillation and the boundedness of all admissible solutions of the difference equation where A, B, C are positive real numbers

Amyloid Inspired Self-Assembled Peptide Nanofibers

Cataloged from PDF version of article.Amyloid peptides are important components in many degenerative diseases as well as in maintaining cellular metabolism. Their unique stable structure provides new insights in developing new materials. Designing bioinspired selfassembling peptides is essential to generate new forms of hierarchical nanostructures. Here we present oppositely charged amyloid inspired peptides (AIPs), which rapidly self-assemble into nanofibers at pH 7 upon mixing in water caused by noncovalent interactions. Mechanical properties of the gels formed by selfassembled AIP nanofibers were analyzed with oscillatory rheology. AIP gels exhibited strong mechanical characteristics superior to gels formed by self-assembly of previously reported synthetic short peptides. Rheological studies of gels composed of oppositely charged mixed AIP molecules (AIP-1 + 2) revealed superior mechanical stability compared to individual peptide networks (AIP-1 and AIP-2) formed by neutralization of net charges through pH change. Adhesion and elasticity properties of AIP mixed nanofibers and charge neutralized AIP-1, AIP-2 nanofibers were analyzed by high resolution force− distance mapping using atomic force microscopy (AFM). Nanomechanical characterization of self-assembled AIP-1 + 2, AIP-1, and AIP-2 nanofibers also confirmed macroscopic rheology results, and mechanical stability of AIP mixed nanofibers was higher compared to individual AIP-1 and AIP-2 nanofibers self-assembled at acidic and basic pH, respectively. Experimental results were supported with molecular dynamics simulations by considering potential noncovalent interactions between the amino acid residues and possible aggregate forms. In addition, HUVEC cells were cultured on AIP mixed nanofibers at pH 7 and biocompatibility and collagen mimetic scaffold properties of the nanofibrous system were observed. Encapsulation of a zwitterionic dye (rhodamine B) within AIP nanofiber network was accomplished at physiological conditions to demonstrate that this network can be utilized for inclusion of soluble factors as a scaffold for cell culture studies. Copyright © 2012 American Chemical Societ