Peeling and diagonal tension failures in steel plated R/C beams

This paper focuses on the design of an experimental investigation motivated by the need to identify various independent modes of failure of steel plated R/C beams. Parameters controlling the various failure modes are identified, and an elaborate testing program confirms existence of peeling failure and flexural failure in addition to isolation of a diagonal tension mode of failure. An expression is proposed to predict ultimate capacity of steel plated R/C beams prone to fail by diagonal tension.     

Influence of atmosphere on redox structure of BaCe0.9Y0.1O2.95 – Insight from neutron diffraction study

High-resolution neutron powder diffraction data were collected at different temperatures and pressure under hydrogen or oxygen under high and low humidities. The samples were loaded in sealed quartz tubes in dry or wet conditions at 0.33 atm pressure and 295 K temperature, and heated up to 973 K during measurements. Rietveld refinement of neutron diffraction data showed that the structure changed from primitive orthorhombic (space group Pbnm) to body centred orthorhombic (Imma) to rhombohedral (R-3c) on heating from room temperature to 973 K. At 623 K temperature and 0.71 atm pressure, the unit-cell volume is higher in wet hydrogen and oxygen atmosphere than dry atmosphere due to proton uptake. Oxygen site occupancies were directly determined as functions of temperature for dry and wet conditions in both oxidising and reducing conditions in order to probe actual oxygen/hydroxyl contents under the conditions relevant to most fuel cell or transport studies.     

Fabrication of poly(D,L‐lactic acid) nanoparticles as delivery system for sustained release of L‐theanine

L‐theanine is present in tea as a unique, free, non‐protein amino acid. Due to various beneficial effects on brain activity, it is widely used as a nutraceutical. After consumption, it is rapidly absorbed and metabolised followed by excretion through urine. Therefore, the authors developed an L‐theanine delivery system by encapsulating into polymeric nanoparticles to release it slowly and make it available for a longer period of time. Poly(D, L‐lactic acid) nanoparticle (PLANP) was fabricated by the double emulsion method and L‐theanine was encapsulated into it (PLANP‐T). Spherical nanoparticles with a hydrodynamic diameter of 247 and 278 nm and surface charge of −14.5 and −25.7 mV for PLANP and PLANP‐T, respectively, were fabricated. The Fourier transform infrared spectroscopic data indicated encapsulation of L‐theanine into PLANP. The PLANP showed high L‐theanine encapsulation capacity (71.65%) with a sustained release character. The maximum release (66.3%) of L‐theanine was recorded in pH 7.3 at 48 h. The release kinetics followed the Higuchi model and the release mechanism was determined as super case‐II transport (erosion). This slow release will make it available to the target tissue for a longer period of time (sustain release effect) and will also avoid immediate metabolism and clearance from the circulation.Inspec keywords: nanomedicine, pH, polymers, nanofabrication, emulsions, biomedical materials, drug delivery systems, nanoparticles, Fourier transform infrared spectraOther keywords: brain activity, L‐theanine delivery system, polymeric nanoparticles, double emulsion method, spherical nanoparticles, surface charge, L‐theanine encapsulation capacity, poly(D, L‐lactic acid) nanoparticles, nonprotein amino acid, urine, hydrodynamic diameter, Fourier transform infrared spectroscopy, time 48.0 hour, voltage ‐25.7 mV, voltage ‐14.5 mV, size 278.0 nm, size 247.0 nm, target tissue, Higuchi model, pH     

Field testing of arsenic in groundwater samples of Bangladesh using a test kit based on lyophilized bioreporter bacteria

A test kit based on living, lyophilized bacterial bioreporters emitting bioluminescence as a response to arsenite and arsenate was applied during a field campaign in six villages across Bangladesh. Bioreporter field measurements of arsenic in groundwater from tube wells were in satisfying agreement with the results of spectroscopic analyses of the same samples conducted in the lab. The practicability of the bioreporter test in terms of logistics and material requirements, suitability for high sample throughput, and waste disposal was much better than that of two commercial chemical test kits that were included as references. The campaigns furthermore demonstrated large local heterogeneity of arsenic in groundwater, underscoring the use of well switching as an effective remedy to avoid high arsenic exposure.     

Effectiveness and reliability of arsenic field testing kits: are the million dollar screening projects effective or not?

The exposure of millions to arsenic contaminated water from hand tube wells is a major concern in many Asiatic countries. Field kits are currently used to classify tube wells as delivering arsenic below 50 microg/L (the recommended limit in developing countries) as safe, painted green or above 50 microg/L, unsafe and painted red. More than 1.3 million tube wells in Bangladesh alone have been tested by field kits. A few million U.S. dollars have already been spent and millions are waiting for the ongoing projects. However, the reliability of the data generated through field kits is now being questioned. Samples from 290 wells were tested by field kits and by a reliable laboratory technique to ascertain the reliability of field kits. False negatives were as high as 68% and false positives up to 35%. A statistical analysis of data from 240 and 394 other wells yielded similar rates. We then analyzed 2866 samples from previously labeled wells and found 44.9% mislabeling in the lower range (<50 microg/L) although mislabeling was considerably reduced in the higher range. Variation of analytical results due to analysts and replicates were pointed out adopting analysis of variance (ANOVA) technique. Millions of dollars are being spent without scientific validation of the field kit method. Facts and figures demand improved, environmentally friendly laboratory techniques to produce reliable data.     

STUDIES ON SLUDGE FROM STORAGE TANK OF WAXY CRUDE OIL PART - I : STRUCTURE AND COMPOSITION OF DISTILLATE FRACTIONS

Tank bottom sludge from storage tanks of Bombay High crude oil deposited during ten years have been studied. The yield of the sludge is approximately 0.1% wt. of the crude oil through-put. The residue boiling above 500°C amounts to over 50%. The distillate fractions collected at 50°C intervals have been analysed extensively and compared to fractions from whole crude of same boiling range. The sludge distillate are distinctly more paraffinic in nature.     

Reuse of wastewater effluent for irrigation in severely arid regions

Al‐Hassa oasis, with an estimated population of 750000, is one of the main agricultural areas in Saudi Arabia. The estimated present agricultural water consumption in the oasis is almost 419 × 10⁶ m³ per year and the water is mainly supplied from the aquifer systems in the oasis. The climate is severely arid and the groundwater resources are limited. A deficiency in irrigation water supplies would occur in the oasis, especially during the summer season, without the reuse of wastewater effluent. Alternative schemes were developed on the basis of climatic, irrigation method, crop, health and economic considerations for the potential reuse of wastewater effluent for irrigation purposes. The schemes suggested different alternatives for reuse of the untreated effluent or with various types of additional treatments needed to render the water free of health hazards and suitable for agricultural use. An expected average wastewqter effluent of about 32.2 × 10⁶ m³/year will be available for irrigation purposes. This will result in minimizing the mining of groundwater and in conserving the water resources in Al‐Hassa oasis.     

Activity of Pt(II) and Ru(III) Triazolopyrimidine Complexes Against Parasites of the Genus Leishmania, Trypanosomas and Phytomonas

The synthesis and characterization of two Pt(II) Complexes with the isomeric ligands 4,5-dihydro-5-oxo- [1,2,4]triazolo-[ 1,5-a]pyrimidine (5HtpO) and 4,7-dihydro-7-oxo-[ 1,2,4]-triazolo-[ 1,5-a]pyrimidine (7HtpO) are described, as well as a Ru(III) complex with 7HtpO. The crystal structure of cis-[PtCl(2)(7HtpO)(2)].2H(2)O has been solved by X-ray diffraction analysis. In vitro activity of the new isolated complexes against the epimastigote form of T. cruzi, procyclic form of T. b. brucei and promastigote form of L. donnovani and P. characias has also been studied. The three complexes markedly affect the growth of the parasites and none of them shows cytotoxicity against macrophage of the J774.2 line at the heaviest dosages used.     

A computational and experimental study on the effective properties of Al2O3‐Ni composites

It has been demonstrated that effective medium approximation and mean field homogenization technique is a useful computational tool to predict the effective thermal and structural properties of alumina‐nickel (Al₂O₃‐Ni) composites. Nickel particle size and volume fraction, thermal interface resistance and porosity are found significant factors that affect thermal conductivity, elastoplastic behavior, elastic modulus and thermal expansion coefficient of Al₂O₃‐Ni composite. To complement the computational design, Al₂O₃‐Ni composite samples with designed range of volume fractions and nickel particle size are developed using spark plasma sintering process and properties are measured for model verification.     

Regeneration of spent earth by wet oxidation

Regeneration of deoiled spent earth by wet oxidation has been investigated. Molecular oxygen was used as an oxidizing agent. Effects of operating parameters such as speed of agitation, temperature, oxygen partial pressure, slurry concentration, and cycle of regeneration have been studied. Kinetics of regeneration was found to be first order with substrate concentration and also with dissolved oxygen concentration. Decolorization capacity of regenerated earth was the same as that of its virgin bleaching earth. Adsorption isotherm data was fitted in Freundlich equation. The values of Freundlich constants of regenerated earth were comparable with the values of virgin bleaching earth.