Cloud Point Extraction with Liquid Ion Exchange for Separation and Determination Magnesium (II) as anion

Liquid Ion Exchange joined with Cloud point extraction methodology was used for the separation of Magnesium (II) from aqueous and determine whereas 10 mL aqueous solution that contains 50 µg Mg2+ ion is complex with 1×10-3M 8-Hydroxy quinoline (8-HQ) at a suitable basic medium it well give higher extraction efficiency at optimum conditions, needs heating the aqueous solution in suitable temperature degree for enough time to form a cloud point layer (CPL). Therefore, the optimum conditions that yielded the good CPL have a small aggregation volume which is appropriate for continuing the ion pair association Complex between Magnesium ion and 8-Hydroxy quinoline.

THE STRENGTH OF NANOCOMPOSITES POLYMER / 2D-NANOFILLER WITH ULTRASMALL FILLER CONTENTS

The theoretical model, using the notions of fractal analysis is proposed for description of strength of nanocomposites polymer/2D-nanofiller on the example of nanocomposites polyvinylalcohol/boron nitride. For correct description of strength of these two-phase nanomaterial the knowledge of initial characteristics of matrix polymer (stress of fracture), geometrical parameters of nanofiller and level of interfacial adhesion polymer matrix-nanofiller is necessary. The indicated level, characterizing by shear interfacial strength, was determined theoretically within the framework of fractal conception of adhesion. Its absolute values found high enough – they are comparable with this characteristic in systems polymer-carbon nanotubes and are higher essentially than in systems polymer-microfiber (glassy and carbon fibers). This factor defines high enough strength of the considered nanocomposites. The important factor for fracture process of nanomaterials is aggregation of initial platelets of nanofiller, which forms “packets” (tactoids) of such platelets. The relatively small aggregation degree of nanofiller gives appreciable reduction of strength of nanocomposites polymer/2D-nanofiller. The indicated reduction is connected with transition of 2D-nanofiller structure from exfoliated to intercalated one, i.e. from separate platelets to their tactoids.

A new CT scan methodology to characterize a small aggregation gravel clast contained in a soft sediment matrix

Over the past decades, X-ray computed tomography (CT) has been increasingly applied in the geosciences community. CT scanning is a rapid, non-destructive method allowing the assessment of relative density of clasts in natural archives samples. This study focuses on the use of this method to explore instantaneous deposits as major contributors to sedimentation of high-elevation lakes in the Alps, such as the Lake Lauvitel system (western French Alps). This lake is located within a very steep valley prone to episodic flooding and features gullies ending in the lake. This variety of erosion processes leads to deposition of sedimentary layers with distinct clastic properties. We identified 18 turbidites and 15 layers of poorly sorted fine sediment associated with the presence of gravels since AD 1880. These deposits are respectively interpreted as being induced by flood and wet avalanche. This constitutes a valuable record from a region where few historical records exist. This CT scan approach is suitable for instantaneous deposit identification to reconstruct past evolution and may be applicable to a wider variety of sedimentary archives alongside existing approaches.

Effects of Long Chain Cellulose Ester on Mechanical Properties of Polylactic Acid Reinforced with Microcrystalline Cellulose

Long chain cellulose ester (LCCE) synthesized by acylation reaction via microwave process was used as a compatibilizer for banana stem microcrystalline cellulose/polylactic acid (BS MCC/PLA) composite. The proper reaction time and power output for LCCE synthesis were 150 second and 160 watt, respectively, which resulted in the highest weight increase (%) of LCCE synthesis. The FT-IR and NMR results confirmed that long chain acyl ester was grafted on cellulose structure. The degree of substitution (DS) of LCCE was 2.41. The BS MCC content was fixed at 40wt% while LCCE content was varied from 0-9 wt%. The Tensile properties properties of BS MCC/PLA composites with or without LCCE were studied by tensile test. The results revealed that the addition of LCCE enhanced the elongation at break of 40wt% BS MCC/PLA composite owing to the improvement of compatibility between PLA and MCC, particularly the addition of 5wt% of LCCE which led to the highest elongation at break. However, when the addition of LCCE was greater than 5wt%, the elongation at break was slightly decreased because of the small aggregation of BS MCC and LCCE in PLA matrix as supported by morphological analysis. Nevertheless, the addition of LCCE contributed to the decrease in tensile strength and Young’s modulus of 40wt% BS MCC/PLA composite slightly because of the decreasing of crystallinity in PLA composite.

Improving the Performance of HVOF Sprayed WC-Co Coatings Using Statistical Design

This study reports the statistical optimization of experiments, designed by Taguchi, to improve the wear-resistance of the tungsten carbide/cobalt-based coatings applied using high-velocity oxygen-fuel (HVOF) spraying processes. In this study, a group of needlelike textures appeared in the HVOF WC-Co coatings. The structures were evenly distributed and compacted closely, showing a more dense and homogenous configuration. The coating that formed with a large amount of pores, microcracks and unmolten particles was much looser, and the interface was locally prone to defects. The coatings were obviously not homogenous. Experimental results show that the wear-resistant coatings are highly dense, with an elastic lamellar structure. The tribological properties were significantly improved and the surface textures showed uniformity, in a molten droplet flattened formation. A homogenous, morphological structure, with local small aggregation, was more obvious after HVOF WC-Co coating. Accordingly, it is clear that the surface properties determined proved favorable to the mechanical properties of the WC/Co coatings. In addition, we compared the linear models with the quadric models, using RSM methods, in all the experiments. Statistically, the linear models produced an average error of 8.285％, while the quadric models generated an average error of 1.399％. It is clear that the RSM models successfully fitted the HVOF WC-Co coating process and the quadric models yielded more accurate predictions than the linear models, in most cases. The proposed procedure was applied to HVOF spraying of WC-CO coatings. The results demonstrated its feasibility and its effectiveness in improving the HVOF WC-Co coating.

Role of the Streptococcus mutans irvA Gene in GbpC-Independent, Dextran-Dependent Aggregation and Biofilm Formation

ABSTRACT Dextran-dependent aggregation (DDAG) of Streptococcus mutans is an in vitro phenomenon that is believed to represent a property of the organism that is beneficial for sucrose-dependent biofilm development. GbpC, a cell surface glucan-binding protein, is responsible for DDAG in S. mutans when cultured under defined stressful conditions. Recent reports have described a putative transcriptional regulator gene, irvA, located just upstream of gbpC, that is normally repressed by the product of an adjacent gene, irvR. When repression of irvA is relieved, there is a resulting increase in the expression of GbpC and decreases in competence and synthesis of the antibiotic mutacin I. This study examined the role of irvA in DDAG and biofilm formation by engineering strains that overexpressed irvA (IrvA+) on an extrachromosomal plasmid. The IrvA+ strain displayed large aggregation particles that did not require stressful growth conditions. A novel finding was that overexpression of irvA in a gbpC mutant background retained a measure of DDAG, albeit very small aggregation particles. Biofilms formed by the IrvA+ strain in the parental background possessed larger-than-normal microcolonies. In a gbpC mutant background, the overexpression of irvA reversed the fragile biofilm phenotype normally associated with loss of GbpC. Real-time PCR and Northern blot analyses found that expression of gbpC did not change significantly in the IrvA+ strain but expression of spaP, encoding the major surface adhesin P1, increased significantly. Inactivation of spaP eliminated the small-particle DDAG. The results suggest that IrvA promotes DDAG not only by GbpC, but also via an increase in P1.

100 years of Belgian rainfall: are there trends?

In 1999 the digitisation of old rainfall records of measurements at Uccle (Belgium) was completed, which resulted in a unique rainfall series of 100 years (period 1898-1997). This is an ideal opportunity to search for trends in the rainfall over the last century. Large variations in rainfall probability over the century have been observed. For small aggregation levels there is a small decrease in extreme rainfall events over the century. For large aggregation levels there is a more explicit increase in extreme rainfall. Because the rainfall on seasonal aggregation level is only slightly increased, the increase in extreme rainfall events for aggregation levels between a few days and a few months can only occur due to larger clustering. However, the final conclusion is that no significant trend can be observed. A pure random variation of the rainfall can cause equally large variations. This does not exclude a possible trend in flooding frequency, due to the strong increase in urbanisation over the last century.

Use of acoustics to assess a small aggregation of orange roughy, Hoplostethus atlanticus (Collett), off the eastern coast of Tasmania

A relatively small aggregation of orange roughy (Hoplostethus atlancticus) was located in April 1989 off the eastern coast of Tasmania. A Simrad EK400 (38 kHz) scientific echo-sounder was used to survey the aggregation over a period of eight days, during which time the aggregation was commercially fished. The aggregation was confined to an area of approximately 4 km2, with the dimensions of the aggregation varying within and between days. High densities of orange roughy were located near the bottom on some days and more than 24 m off the bottom on others. Average fish densities during the survey and an estimate of the extremes of densities (fish m-3) are presented. Estimates of the original biomass of this aggregation as obtained from acoustic data and commercial catch-and-effort data are compared, and the mean target strength of the population is estimated.