Suitability of Soil Washed Sand as Fine Aggregates to Replace River Sand in the Concrete

This paper presents a study on suitability of replacing river sand with soil washed sand as fine aggregate in concrete. The study was based on a comparison of concrete performance produced from river sand and soil washed sand obtained from four locations in Sri Lanka; Homagama, Rathnapura, Anuradhapura and Bandarawela. Several standard tests including Sieve analysis, Slump test and Compressive strength were conducted in order to check the workability, particle size distribution and compressive strength of M25 grade concrete. From the test results, it was found that percentages of coarse sand, medium sand and fine sand present in soil washed sand are higher than that of river sand, while highly coarse sand percentage was higher for the soil samples extracted from Rathnapura and Bandarawela areas compared to river sand. Slump test results showed that the concrete produced from river sand has a lower slump value compared to that of concrete produced from soil washed sand, suggesting that washed soil sand could possess higher workability. Test results showed that specimen cubes have achieved the target strength of M25 grade concrete even though compressive strength of concrete produced from soil washed sand was about 10% lesser compared that of river sand at 7 days, 14 days and 28 days’ strength

Tandem mass spectrometry and ion-molecule interactions: Application to structural characterization of polymers and other compounds

Tandem mass spectrometry (MS/MS), used in conjunction with electron ionization (EI), chemical ionization (CI) and desorption ionization (DCI), has been applied to structural characterization of polysiloxanes and analogs of the anti-malarial artemisinin. In addition, hydrogen-deuterium exchange occurring in the collision cell is applied to elucidate structures of polyfunctional aromatic compounds. Two novel polysiloxanes, with N-methylpyridyl substituents, form abundant cyclic oligomeric ions when heated under DCI conditions. MS/MS product spectra of the cyclic ions reveal characteristic loss of $-$CH\sb2(CH\sb3)NC\sb5H\sb4 group. The lower oligomers are cyclic but oligomers higher than the pentamer are mainly comprised of proton bound dimers of smaller oligomers. Marcovian statistical calculations show that the monomers in the copolymers are non-randomly distributed. Artemisinin, an effective antimalarial agent from Artemisia annua, and its congeners produce abundant ammonium adducts, (M + NH\sb4)\sp+, using ammonia desorption chemical ionization (DCI). Dissociation of the mass-selected adducts yields the protonated molecules, (M + H)\sp+, which subsequently eliminate neutral molecules such as H\sb2O, CO, HCOOH, CH\sb3COOH. A rapid screening method utilizing MS/MS and ammonia DCI is described for artemisinin-analogs. MS/MS neutral loss scans which are selective for different elimination reactions are used to suggest structural features of the analogs present in Artemisia annua L. H/D exchange occurring between mass-selected polyfunctional aromatic ions and deuterated reagents is investigated as a function of interaction time, reagent gas and collision energy. Some reagents such as CH\sb3OD exchange specific types of active hydrogens, such as phenolic and carboxylic hydrogens, without exchanging amino hydrogens, while others such as ND\sb3 exchange all active hydrogens. The proximity of the functional groups, site of protonation and proton affinity difference between the analyte and the reagent gas are important factors in site-specific H/D exchange in polyfunctional compounds. Cluster ion formation plays a major role in the exchange mechanism operating in the triple quadrupole

A novel method to enhance the performance of quasi-solid-state dye-sensitized solar cells based on polyacrylonitrile gel electrolyte and nanoparticles of ZnO with indoline D-358 as the dye

A novel way to overcome incomplete pore filling when using polymer gel electrolytes for dye-sensitized solar cells is herein described. The pores of the indoline D-358-coated ZnO nanostructure were first filled with the liquid electrolyte, the polyacrylonitrile (PAN) gel electrolyte was subsequently placed on it, and the quasi-solid-state dye-sensitized solar cell was fabricated in the usual manner. In other cells, the PAN film was subjected to hot pressing without the liquid electrolyte filling and pressing (without heating) with the gel electrolyte. Out of several different cell configurations studied, the cell containing hot-pressed polymer film without the liquid electrolyte gave an efficiency of 2.80% with D-358 dye while the introduction of a thin film of the liquid electrolyte followed by pressing the gel polymer film increased the efficiency to 4.31%

Preparation of fluoride-doped tin oxide films on soda-lime glass substrates by atomized spray pyrolysis technique and their subsequent use in dye-sensitized solar cells

The development of a novel method for the fabrication of low-cost, transparent, conducting glass (F--doped SnO2 layer on soda lime glass, FTO) by a specially developed atomized spray pyrolysis technique using cheap soda lime glass in place of commercially used expensive glass at a comparatively lower temperature of 450 degrees C is presented. The use of these FTO plates in dye-sensitized solar cells (DSCs) will also be described. The optimum temperature of 450 degrees C for the FTO layer on soda lime glass is obtained by carrying out atomized spray pyrolysis of the precursor solution onto the soda lime glass substrate at several different temperatures and by characterizing the materials obtained at each temperature by X-ray diffraction analysis. The FTO layers formed at 450 degrees C have also been characterized by scanning electron microscopy (SEM) for morphology, grain size, and film thickness and by UV-visible transmittance spectroscopy for the optical transmission in the visible range. The electrical properties of the FTO film prepared at 450 degrees C are estimated by the van der Pour method and Hall measurements. The FTO films have a uniform texture with smaller grains (>= 50 nm) embedded in cages formed by larger particles