Raman spectrum of diglycine barium chloride monohydrate

The Raman spectrum of diglycine barium chloride monohydrate in the single crystal form has been recorded using λ 2536·5 excitation. 43 Raman lines (9 lattice and 34 internal) have been recorded. Satisfactory assignments have been given for most of the observed Raman lines. It is concluded from a comparison of the Raman spectrum of this compound with those of glycine and of other addition compounds of glycine, that the glycine unit exists in the zwitterion form in the structure of diglycine barium chloride monohydrate.

Infra-red and raman spectra of BaCl2.2H2O and BaCl2.2D2O

The infra-red and Raman spectra of ordinary and deuterated barium chloride dihydrate have been studied to throw light on the intramolecular hydrogen bonds in these two crystals. The frequencies of the stretching, bending and librational modes observed in infra-red and Raman spectra exclude the possibility of at least one of the OH.... Cl hydrogen bonds, contrary to the results of NMR and neutron diffraction studies.

High-temperature reactions of alkali and plagioclase feldspars with alkali and alkaline-earth chlorides-formation of celsian

High-temperature reactions (Ca 900-degrees-C) involving albite, K-feldspar or plagioclase and K, Ba-or K, Sr chlorides were experimentally studied. These experiments reveal that the reaction between K-exchanged albite, potash feldspar, or plagioclase and Ba-chloride/Ba-K chloride results in the formation of celsian by the breakdown of the starting feldspar structure above 800-degrees-C. Sr-feldspar does not form under similar conditions. A size-effect of the large M-site cation appears to be responsible for the formation of celsian. The reaction between K-feldspar and barium chloride may be used as a method for synthesizing celsian.

Measurement of axial dispersion coefficient in a packed bed using X-ray

Dispersion of the liquid in a porous media is of great importance in many areas of engineering and has been studied by several researchers so far. A new experimental method has been developed to measure the dispersion coefficient. X-ray absorption technique provides a better understanding of dispersion that characterizes the mixing phenomenon in the packed beds. This is because the method is non-invasive and also it gives tracer concentration data at every point within the bed. The axial dispersion in a cylindrical bed of non-porous and non-wetting spherical particles has been measured for the flow of water. Aqueous barium chloride solution has been used a as tracer. X-ray images, recorded on a videocassette, have been analyzed using an image processing software to extract the local interstitial velocity and concentration data in the bed. Local dispersion coefficient has been determined with the help of aforementioned data. By using these data, the overall dispersion coefficient in a packed bed can also be estimated.

FLOTATION OF QUARTZ WITH SOAPS OF BOMBAX MALABARICA OIL AND SHARK LIVER OIL AS COLLECTORS

An attempt has been made to use the indigeneous oils-Bombax Malabarica oil and Shark liver oil in the form of sodium soaps as collectors in the flotation of quartz using barium chloride as activator. The effect of pH, collector concentration and activator concentration on the flotation of quartz is studied in a Leaf and knoll flotation cell. The experiments show that it is possible to obtain 98.0 per cent of quartz as float using 10 mg. of Bombax. Malabarica oil and Shark liver oil soaps at pH values of more than 7.0 and when barium ion concentration is in excess of that required to form barium soaps. Bombax Malabarica oil is found to be superior to Shark liver oil as collector in the flotation of quartz.

Construction and evaluation of cysteine selective electrodes for FIA analysis of pharmaceuticals

A flow injection analysis (FIA) system comprising a cysteine selective electrode as detection system was developed for determination of this amino acid in pharmaceuticals. Several electrodes were constructed for this purpose, having PVC membranes with different ionic exchangers and mediator solvents. Better working characteristics were attained with membranes comprising o-nitrophenyl octyl ether as mediator solvent and a tetraphenylborate based ionic-sensor. Injection of 500 µL standard solutions into an ionic strength adjuster carrier (3x10-3 M) of barium chloride flowing at 2.4mL min-1, showed linearity ranges from 5.0x10-5 to 5.0x10-3 M, with slopes of 76.4±0.6mV decade-1 and R2>0.9935. Slope decreased significantly under the requirement of a pH adjustment, selected at 4.5. Interference of several compounds (sodium, potassium, magnesium, barium, glucose, fructose, and sucrose) was estimated by potentiometric selectivity coefficients and considered negligible. Analysis of real samples were performed and considered accurate, with a relative error to an independent method of +2.7%.

A study on mitigating the effect of sulphates in lime stabilised Cochin marine clays

Soft clays known for their high compressibility, low stiffness and low shear strength are always associated with large settlement. In place soil treatment using calcium-based stabilizers like lime and cement is a feasible solution to readdress strength deficiencies and problematic shrink/swell behaviour of unstable subgrade soils. Out of these, lime has been proved unambiguously as the most effective and economical stabilising agent for marine clays. Lime stabilisation creates long-term chemical changes in unstable clay soils to create strong, but flexible, permanent structural layers in foundations and other pavement systems. Even though calcium-based stabilizers can improve engineering properties of soft clays, problems can arise when they are used in soils rich in sulphates. It is possible for marine clays to be enriched with sulphates, either by nature or due to the discharge of nearby industrial wastes containing sulphates. The presence of sulphates is reported to adversely affect the cation exchange and pozzolanic reactions of cement and lime treated soil systems. The anions of sulphates may combine with the available calcium and alumina, and form insoluble ettringite in the soil system. Literature on sulphate attack in lime treated marine clays reports that formation of ettringite in lime-sodium sulphate-clay system is capable of adversely affecting the engineering behavior of marine clays. Only very few studies have been conducted on soft marine clays found along the coastal belt of Kerala and that too, is limited to Cochin marine clays. The studies conducted also have the limitation that the strength behaviour of lime stabilised clay was investigated only for one year. Practically no data pertaining to long term adverse effects likely to be brought about by sulphates on the strength and compressibility characteristics of Cochin marine clays is available. The overriding goal of this investigation was thus to examine the effectiveness of lime stabilisation in Cochin marine clays under varying sulphate contents. The study aims to reveal the changes brought about by varying sulphate contents on both physical and engineering properties of these clays stabilised by lime and the results for various curing periods up to two years is presented in this thesis. Quite often the load causing an unacceptable settlement may be less than the load required to cause shear failure and therefore attempt has been made in this research to highlight sulphate induced changes in both the compressibility and strength characteristics of lime treated Cochin marine clays. The study also aimed at comparing the available IS methods for sulphate quantification and has attempted to determine the threshold level of sulphate likely make these clays vulnerable by lime stabilisation. Clays used in this study were obtained from two different sites in Kochi and contained sulphate in two different concentrations viz., 0.5% and 0.1%. Two different lime percentages were tried out, 3% and 6%. Sulphate content was varied from 1% to 4% by addition of reagent grade sodium sulphate. The long term influence of naturally present sulphate is also investigated. X-ray diffraction studies and SEM studies have been undertaken to understand how the soil-lime reactions are affected in the presence of sodium sulphate. Natural sulphate content of 0.1% did not seem to have influenced normal soil lime reactions but 0.5% sulphate could induce significant changes adversely in both compressibility and strength behaviour of lime treated clays after long duration. Compressibility is seen to increase drastically with increasing sulphate content suggesting formation of ettringite on curing for longer periods. Increase in compression index and decrease in bond strength with curing period underlined the adverse effects induced in lime treated marine clays by the presence of sulphates. Presence of sulphate in concentrations ranging from 0.5 % to 4% is capable of adversely affecting the strength of lime treated marine clays. Considerable decrease is observed with increasing concentrations of sulphate. Ettringite formation due to domination of sodium ions in the system was confirmed in mineralogical studies made. Barium chloride and barium hydroxide is capable of bringing about beneficial changes both in compressibility and strength characteristics of lime treated Cochin marine clays in the presence of varying concentrations of sulphate and is strongly influenced by curing time. Clay containing sodium sulphate has increased strength values when either of barium compounds was used with lime ascompared with specimens treated with lime only. Barium hydroxide is observed to remarkably increase the strength as compared to barium chloride,when used in conjunction with lime to counteract the effect of sulphate.

Ionothermal synthesis of the mixed-anion material, Ba3Cl4CO3

A low-temperature ionothermal method for the facile synthesis of the halide carbonate, Ba3Cl4CO3, in single-crystalline form has been developed. This has enabled the first determination of the crystal structure of this material to be carried out. Analysis of single-crystal X-ray diffraction data indicates that barium chloride carbonate crystallises in the orthorhombic space group Pnma (Z=4), with a=8.4074(11), b=9.5886(12), c=12.4833(15) Å (Rw=0.0392). It exhibits a complex structure in which a three-dimensional network is formed from cross-linking of chains of anion-centred octahedra that share faces.

Ação antiarrítmica do isofluorano em cães submetidos à arritmias ventriculares induzidas por cloreto de bário

Avaliou-se a ação antiarrítmica do isofluorano em cães submetidos a arritmias ventriculares pelo uso de cloreto de bário, utilizando-se de seis cães, machos e fêmeas, que receberam uma dose de 3mg/kg de peso IV de cloreto de bário a 2,5% (G1). O mesmo protocolo foi repetido, nos mesmos animais, sob anestesia geral com isofluorano (G2). Usou-se a eletrocardiografia computadorizada para avaliar o ritmo cardíaco, a duração e/ou amplitude das ondas e os intervalos eletrocardiográficos. Não se verificou alteração no ritmo cardíaco em G2, diferente de G1, que apresentou freqüentes arritmias ventriculares na forma de bigeminismo e taquicardia ventricular multifocal. Houve diferença significativa entre os grupos em relação à freqüência cardíaca nos minutos iniciais de observação, quando ocorreu aumento na freqüência cardíaca em G1. A utilização do isofluorano conferiu ação antiarrítmica em cães com arritmias induzidas pelo cloreto de bário, reforçando suas indicações a pacientes com risco considerável de desenvolvimento de arritmias ventriculares.

Construction and performance of a drop cell for the nephelometric determination of sulfur dioxide

A nephelometric technique based on a liquid drop is described for the measurement of atmospheric sulfur dioxide. A 40-mul drop of barium chloride and hydrogen peroxide solution is suspended in a flowing-air sampling stream. The sulfur (IV) collected is oxidized to sulfur (VI) and finally precipitated as barium sulfate. Nephelometric detection of drop is achieved by an appropriate arrangement consisting of an optical fiber contacting the drop and a photodiode placed at 90degrees relative to the fiber. The design and characteristics of this drop-based gas sensor system are described. The analytical response, as photocurrent, is proportional to the product of the sampling period and the sulfur dioxide concentration. The detection limit is ca. 1.1 mg m(-3) for a 10-min sampling time. The present technique is fairly rapid and simple, uses a small amount of reagent and is set up with low-cost equipment, making this system economically viable. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Production and partial characterization of keratinase produced by a microorganism isolated from poultry processing plant wastewater

A Streptomyces was isolated from poultry plant wastewater, showed high keratinolytic activity when cultured on feather meal medium. Optimum keratinolytic activity was observed at 40°C and pH 8.0. The enzyme also showed to be stable between 40 and 60°C. The keratinolytic activity was not inhibited by EDTA, DMSO and Tween 80. On the other hand, CaCl2, ZnCl2, and BaCl2 slightly inhibited the keratinolytic activity. The Streptomyces isolated might be useful in leather, keratin waste treatment, animal feeding industry, and also cosmetic industry. © 2008 Academic Journals.

Purification, characterization, and specificity determination of a new serine protease secreted by penicillium waksmanii

The purpose of this work was to purify a protease from Penicillium waksmanii and to determine its biochemical characteristics and specificity. The extracellular protease isolated that was produced by P. waksmanii is a serine protease that is essential for the reproduction and growth of the fungus. The protease isolated showed 32 kDa, and has optimal activity at pH 8.0 and 35 C towards the substrate Abz-KLRSSKQ-EDDnp. The protease is active in the presence of CaCl2, KCl, and BaCl, and partially inhibited by CuCl2, CoCl2 and totally inhibited by AlCl3 and LiCl. In the presence of 1 M urea, the protease remains 50 % active. The activity of the protease increases 60 % when it is exposed to 0.4 % nonionic surfactant-Triton X-100 and loses 10 % activity in the presence of 0.4 % Tween-80. Using fluorescence resonance energy transfer analysis, the protease showed the most specificity for the peptide Abz-KIRSSKQ-EDDnp with k cat/K m of 10,666 mM-1 s-1, followed by the peptide Abz-GLRSSKQ-EDDnp with a k cat/K m of 7,500 mM -1 s-1. Basic and acidic side chain-containing amino acids performed best at subsite S1. Subsites S2, S3, S′ 2, and S′ 1, S ′ 3 showed a preference for binding for amino acids with hydrophobic and basic amino acid side chain, respectively. High values of k cat/K m were observed for the subsites S2, S3, and S′ 2. The sequence of the N-terminus (ANVVQSNVPSWGLARLSSKKTGTTDYTYD) showed high similarity to the fungi Penicillium citrinum and Penicillium chrysogenum, with 89 % of identity at the amino acid level. © 2012 Springer Science+Business Media New York.

Dinamica dell’intrusione salina nella costa ravennate: aspetti idrogeochimici ed evoluzione attesa

Nell’ambito del progetto multidisciplinare “Coastal Salt Water Intrusion”, che si propone di indagare “l’Intrusione salina nella costa ravennate con i conseguenti impatti territoriali-ambientali, connessi al previsto innalzamento del livello marino per cause climatiche e di subsidenza”, si inserisce il presente studio con l’obiettivo di fornire una caratterizzazione idrogeochimica delle acque di falda e superficiali e un modello geochimico generale sui processi di salinizzazione o desalinizzazione in atto nella falda freatica costiera della costa ravennate. E’ stato fatto un confronto fra tre metodiche di estrazione del complesso di scambio della matrice solida dell’acquifero che utilizzano rispettivamente acetato di ammonio, cloruro di bario e argento-tiourea. Sono stati posizionati 5 transetti perpendicolari alla linea di costa per un totale di 44 punti di campionamento con due campagne di prelievi, al termine della primavera e al termine dell’estate. La caratterizzazione dei processi di mixing e scambio ionico con la matrice solida dell’acquifero è avvenuta mediante analisi dei cationi ed anioni fondamentali, determinazione della CEC sulla matrice solida dell’acquifero, modellizzazione mixing/scambio ionico, modellizzazione della composizione teorica della frazione scambiabile in funzione della composizione acqua all’equilibrio e interpolazione geostatistica dei dati raccolti e costruzione di mappe geochimiche (curve di iso-concentrazione). La metodologia di estrazione che utilizza il bario-cloruro è risultata la più affidabile. Le acque prelevate dalla falda superficiale evidenziano miscelazione in varie proporzioni acqua marina/acqua dolce, scambi ionici per interazione acqua/sedimento, dissoluzione di CaSO4.2H2O. I processi di salinizzazione e/o addolcimento mostrano una significativa variabilità nello spazio (variabilità legata alla distanza dalla costa, al profilo topografico e alla distribuzione dei corpi sabbiosi litoranei) e nel tempo (variabilità legata alla piovosità e alla gestione delle acque superficiali e del sottosuolo). La complessa variabilità spazio-temporale dei processi in atto nella falda superficiale non consente di evidenziare una complessiva prevalenza di fenomeni di salinizzazione rispetto a quelli di addolcimento.

Dissolution-Precipitation in Porous Media: Experiments and Modelling

The evolution of porosity due to dissolution/precipitation processes of minerals and the associated change of transport parameters are of major interest for natural geological environments and engineered underground structures. We designed a reproducible and fast to conduct 2D experiment, which is flexible enough to investigate several process couplings implemented in the numerical code OpenGeosys-GEM (OGS-GEM). We investigated advective-diffusive transport of solutes, effect of liquid phase density on advective transport, and kinetically controlled dissolution/precipitation reactions causing porosity changes. In addition, the system allowed to investigate the influence of microscopic (pore scale) processes on macroscopic (continuum scale) transport. A Plexiglas tank of dimension 10 × 10 cm was filled with a 1 cm thick reactive layer consisting of a bimodal grain size distribution of celestite (SrSO4) crystals, sandwiched between two layers of sand. A barium chloride solution was injected into the tank causing an asymmetric flow field to develop. As the barium chloride reached the celestite region, dissolution of celestite was initiated and barite precipitated. Due to the higher molar volume of barite, its precipitation caused a porosity decrease and thus also a decrease in the permeability of the porous medium. The change of flow in space and time was observed via injection of conservative tracers and analysis of effluents. In addition, an extensive post-mortem analysis of the reacted medium was conducted. We could successfully model the flow (with and without fluid density effects) and the transport of conservative tracers with a (continuum scale) reactive transport model. The prediction of the reactive experiments initially failed. Only the inclusion of information from post-mortem analysis gave a satisfactory match for the case where the flow field changed due to dissolution/precipitation reactions. We concentrated on the refinement of post-mortem analysis and the investigation of the dissolution/precipitation mechanisms at the pore scale. Our analytical techniques combined scanning electron microscopy (SEM) and synchrotron X-ray micro-diffraction/micro-fluorescence performed at the XAS beamline (Swiss Light Source). The newly formed phases include an epitaxial growth of barite micro-crystals on large celestite crystals (epitaxial growth) and a nano-crystalline barite phase (resulting from the dissolution of small celestite crystals) with residues of celestite crystals in the pore interstices. Classical nucleation theory, using well-established and estimated parameters describing barite precipitation, was applied to explain the mineralogical changes occurring in our system. Our pore scale investigation showed limits of the continuum scale reactive transport model. Although kinetic effects were implemented by fixing two distinct rates for the dissolution of large and small celestite crystals, instantaneous precipitation of barite was assumed as soon as oversaturation occurred. Precipitation kinetics, passivation of large celestite crystals and metastability of supersaturated solutions, i.e. the conditions under which nucleation cannot occur despite high supersaturation, were neglected. These results will be used to develop a pore scale model that describes precipitation and dissolution of crystals at the pore scale for various transport and chemical conditions. Pore scale modelling can be used to parameterize constitutive equations to introduce pore-scale corrections into macroscopic (continuum) reactive transport models. Microscopic understanding of the system is fundamental for modelling from the pore to the continuum scale.

Local liquid holdups and hysteresis in a 2-D packed bed using X-ray radiography

An X-ray visualization technique has been used for the quantitative determination of local liquid holdups distribution and liquid holdup hysteresis in a nonwetting two-dimensional (2-D) packed bed. A medical diagnostic X-ray unit has been used to image the local holdups in a 2-D cold model having a random packing of expanded polystyrene beads. An aqueous barium chloride solution was used as a fluid to achieve good contrast on X-ray images. To quantify the local liquid holdup, a simple calibration technique has been developed that can be used for most of the radiological methods such as gamma ray and neutron radiography. The global value of total liquid holdup, obtained by X-ray method, has been compared with two conventional methods: drainage and tracer response. The X-ray technique, after validation, has been used to visualize and quantify, the liquid hysteresis phenomena in a packed bed. The liquid flows in preferred paths or channels that carry droplets/rivulets of increasing size and number as the liquid flow rate is increased. When the flow is reduced, these paths are retained and the higher liquid holdup that persists in these regions leads to the holdup hysteresis effect. Holdup in some regions of the packed bed may be an order of magnitude higher than average at a particular flow rate. (c) 2005 American Institute of Chemical Engineers