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At least 613 records · Page 34Linked to original sources
PubMed2005

Optimization of medium composition for alkali-stable xylanase production by Aspergillus fischeri Fxn 1 in solid-state fermentation using central composite rotary design.

Response surface methodology and central composite rotary design (CCRD) was employed to optimize a fermentation medium for the production of alkali-stable cellulase-free xylanase by Aspergillus fischeri in solid-state fermentation at pH 9.0 with wheat bran as substrate. The four variables involved in this study were sodium nitrite, potassium dihydrogen phosphate, magnesium sulphate and yeast extract. The statistical analysis of the results showed that, in the range studied, only sodium nitrite had a significant effect on xylanase production. The optimized medium containing (in g/l) NaNO(2)-7.0, K2HPO(4)-1.0, MgSO(4)-0.5 and yeast extract-5.0 resulted in 1.9-fold increased level of alkali-stable xylanase (1024 U/g wheat bran) production compared to initial level (540 U/g) after 72 h of fermentation, whereas its value predicted by the quadratic model was 931 U/g. The level of protease activity was considerably decreased in optimized medium, thus helping to preserve the xylanase activity and demonstrating another advantage of applying statistical experimental design.

Aspergillus↗
PubMed2005

Water structure in aqueous solutions of alkali halide salts: FTIR spectroscopy of the OD stretching band.

Water structure making/breaking studies in solutions of five alkali halide salts (KF, KI, NaI, CsF and CsCl) in 4 wt% D(2)O in H(2)O mixtures have been performed by FTIR analysis of the OD stretching band in the full solubility range. The proposed method gives a microscopic picture of the water structure making/breaking character of the salts in terms of the hydrogen bonding between the water molecules in the solution. With the exception of CsCl, there is a very good correlation of the structure making/breaking character of the salts determined by FTIR analysis, and the viscosity coefficients of the solutions. The results fully support and explain previous studies of bubble attachment to microscopic salt particles of the above salts. The investigations support the primary importance of interfacial water structure in the explanation of the flotation of alkali halide salts in their brines.

Journal Article↗
PubMed2006

The alkali molten globule state of horse ferricytochrome c: observation of cold denaturation.

Here, we present the basic structural properties and the thermodynamic description of a previously unknown alkali molten globule state of horse "ferricytochrome c". Both sodium and guanidinium cations stabilize the alkali-denatured state at pH 13, presumably by a charge screening mechanism. The Na(+)-stabilized conformation (B state) clearly meets with the molecular organizational definition of the generic molten globule state. The B state exhibits highly cooperative thermal unfolding transitions monitored by both near and far-UV CD. Analyses of these transitions show substantial heat capacity change, suggesting that the hydrophobic effect contributes considerably to its energetic stability. At low salt concentration where molten globules are less stable, the B state undergoes reversible cold denaturation.

Animals↗
PubMed2005

Molecular structure of 3-aminobenzoic acid complexes with alkali metals.

The vibration (FT-IR, FT-Raman), electronic (UV-Vis) and NMR (1H and 13C) spectra for 3-aminobenzoic acid and its alkali metal salts were recorded. The influence of lithium, sodium, potassium, rubidium and cesium on the electronic system of the 3-aminobenzoic acid was studied. The assignment of the vibration spectra was done. Characteristic shifts of band wavenumbers and changes in band intensities along the metal series were observed. Good correlation between the wavenumbers of the vibrational bands in the IR and Raman spectra for 3-aminobenzoates and ionic potential, electronegativity, atomic mass and affinity of metal cations were found. The chemical shifts of protons (1H NMR) and carbons (13C NMR) in the series of studied alkali metals were also observed. Optimized geometrical structures of studied compounds were calculated by ab initio and density functional methods.

Aminobenzoates↗
PubMed2006

Spectroscopic characteristics of Sm3+-doped alkali fluorophosphate glasses.

Optical absorption, luminescence and lifetime measurements of Sm(3+)-doped alkali fluorophosphate glasses with molar compositions of 50(NaPO(3))(6)+10TeO(2)+20AlF(3)+19RF+1Sm(2)O(3) (R=Li, Na and K) are described. The variation of optical properties with glass composition plays a dominant role in the determination of efficient laser materials. From the experimental oscillator strengths of f-f electric dipole transitions, the phenomenological Judd-Ofelt parameters have been evaluated and are used to evaluate radiative parameters such as radiative transition probabilities (A(R)), branching ratios (beta(R)), lifetimes (tau(R)) and integrated absorption cross-section (sigma(a)) for various excited levels. The predicted values of tau(R) and beta(R) from the (4)G(5/2) excited level to its lower levels are compared with the experimentally measured values. Stimulated emission cross-sections (sigma(e)) were also determined for (4)G(5/2)-->(6)H(J) (J=5/2, 7/2, 9/2 and 11/2) emission transitions. From the emission transitions of Sm(3+) in these alkali tellurofluorophosphate glasses certain potential laser transitions have been identified.

Fluorides↗
PubMed2005

Impact of mercury atmospheric deposition on soils and streams in a mountainous catchment (Vosges, France) polluted by chlor-alkali industrial activity: the important trapping role of the organic matter.

Total atmospheric Hg contamination in a French mountainous catchment upstream from a chlor-alkali industrial site was assessed using Hg concentrations in the deepest soil horizon, in the stream bottom sediments, in river waters and in bryophytes. The natural background level of Hg content deriving from rock weathering was estimated to 32 ng g(-1) in the deepest soil layers. The soils appear to be Hg contaminated in two stages: atmospheric deposition and leaching through the soil profiles of Hg-organic matter complexes. The Hg enrichment factor (EF(Hg)(Sc)) which could be calculated by normalization to a conservative element like Sc, allows to estimate the major contribution (63% to 95%) of the atmospheric inputs, even in the upper part of the basin. This contribution may be attributed to diffuse regional atmospheric deposition of Hg and is mainly due to the geographic location of the chlor-alkali plant. This study shows for the first time that the mercury enrichment is proportional to the carbon content indicating that most of the atmospheric mercury deposition is trapped by the organic matter contained in the soils and in the stream sediments. The Hg stock in the soils of the upper catchment and the soil erosion contribution to the riverine Hg fluxes are estimated for the first time and allow to assess the Hg residence time. It indicates that Hg is trapped in the soils of such a polluted catchment for probably several thousand years.

Air Pollutants↗
PubMed1982

Solvation properties of natural and synthetic ionophores. I. Stoichiometry of complexes with alkali and alkaline earth cations in aprotic organic solvents.

Ion-solvent interactions play a very important role in the studies of stoichiometry, structure, and stability of complexes of cations with natural and synthetic ionophores. These compounds are extremely useful in study of the interaction of neutral salts with macromolecules and the mechanism of cation transport across biological membranes. Knowledge of the ionophore solvation properties enables one to choose a suitable solvent for complexation studies and to obtain detailed information on the solvent effect. We would like to present in this paper a very simple method of estimating the solvation properties of ionophores. We treat the ligand as an assembly of individual noninteracting binding sites. The solvation properties of solvents can be used to represent the solvation sites in natural and synthetic ligands. The solvation properties are represented by the Gutmann donor number (DN) of the model solvent. We can define the solvation ability of a ligand binding site be "donor number of binding site" (DN binding site), which in turn can be represented by the DN of the appropriate model solvent. The average DN of the ligand (DN average) is defined as [xi ni-1 (DN binding site)i]/n, where n is the number of the ligand binding sites. Comparison of the DN average with the DN solvent, together with the knowledge of the composition of the system, characterizes remarkably well the solvation properties of the ligand. This model explains (a) the stoichiometry of many alkali and alkaline earth cation complexes with natural and synthetic ligands in aprotic organic solvents, (b) the transport of alkali and alkaline earth cations across lipid bilayers, and (c) how polypeptides and proteins interact with neutral salts in solutions.

Cations↗
PubMed1990

Normal expression of myosin fast alkali light chain 3 in the hindlimb muscle of chick embryos paralyzed with curare.

We have used a monoclonal antibody (Mab) raised against the fast alkali light chains of quail pectoral muscle myosin to study the expression of MLC1f and MLC3f in the hindlimb muscle of a staged series of control chick embryos and 16-day embryos that had been paralyzed with curare. The Mab (QBM-2) is highly specific for the fast myosin alkali light chains of chick, hamster, and human muscle myosin. On Western blots, MLC1f is detected in hindlimb actomyosin at all of the stages examined, whereas MLC3f cannot be detected until Embryonic Day 14 (E14). Most of the E16 embryos that had been paralyzed with curare since E4 express detectable levels of both MLC1f and MLC3f in their hindlimb muscles, even though embryos incubated under these conditions do not exhibit spontaneous limb movements. Contrary to other reports, our results demonstrate that muscle contraction is not required for the accumulation of MLC3f. In light of our previous finding that innervation is essential for MLC3f accumulation in limb buds grafted onto the chorioallantoic membrane of chick hosts, these results suggest that some neural influence other than contraction, possibly a trophic factor, may play a role in the developmentally regulated expression of MLC3f in avian limb muscle.

Animals↗
PubMed2002

Estimating distribution and retention of mercury in three different soils contaminated by emissions from chlor-alkali plants: part I.

Mercury emissions from chlor-alkali plants have been past and present sources of soil contamination with Hg. Here we calculate net mercury (Hg) deposition to soils in the vicinity (100-1000-m downwind) of three-chlor alkali plants. Calculations were based on spatial distribution patterns of Hg concentrations in soils, which were extrapolated by kriging. Moreover, we investigated to what extent Hg deposition depends on the elevation of receptors and canopy throughfall. Mercury concentrations in soil exceed background values up to a factor of 56 and show enrichment factors between 2 and 5.8 calculated from the median Hg concentration. Net deposition rates range between 2356 and 8952 microg m(-2) year(-1), which is up to 224-fold the background values. Net deposition of Hg to soils at the three sites varies between 1.2 and 2.4% of total emitted Hg. Highest deposition rates were found at sites with extended elevated or forested areas. Here, Hg concentrations in soils increased by a factor of up to 7.3 in elevated (+180 m) forest areas compared to non-elevated grassland soils.

Air Pollutants↗
PubMed2002

Binding and mobility of mercury in soils contaminated by emissions from chlor-alkali plants.

Chlor-alkali plants are known to be an important source of Hg emissions to the atmosphere and related contamination of soils in their vicinity. In the present study, the results of Hg speciation and mobility of Hg in soils affected by Hg emissions from three chlor-alkali plants are compared. Solid phase mercury speciation analyses was carried out using a mercury-thermo-desorption technique with the aim of distinguishing elemental Hg [Hg(0)] from Hg(II)-binding forms. Mercury species in soil leachates were distinguished using an operationally defined method, which is based on the reactivity of soluble Hg compounds. Results show that the Hg(0) emitted from the plants could not be detected in any of the investigated soils. This indicates quantitative re-emission or oxidation of this Hg species in the atmosphere or soils. In most soils Hg was predominately bound to organic matter. Only in sandy soils deficient in organic matter was Hg, to a larger extent, sorbed onto mineral soil components. Leachable Hg in most soils occurred as non-reactive, soluble organic Hg complexes such as fulvic acid-bound Hg, and reach their highest values (90 microg kg(-1)) in soils rich in organic matter. Concentrations of reactive, soluble Hg compounds were highest in sandy soils where the content of organic matter was low. Leachability of Hg was found to be inhibited in soils with a high content of clayey soil components. The distribution of Hg in soil profiles suggests that migration of Hg to deeper soil layers (approx. 20 cm) is most effective if Hg is bound to soluble organic complexes, whereas reactive Hg or weak Hg complexes are effectively retained in the uppermost soil layer (5 cm) through sorption on mineral surfaces.

Air Pollutants↗
PubMed2003

Atmospheric mercury near a chlor-alkali plant in Sweden.

Atmospheric mercury species/fractions were measured near a chlor-alkali plant in Sweden during August 28 to September 4, 2001. The concentration of total gaseous mercury in the plume from the plant was measured using TEKRAN and GARDIS instruments. Gaseous elemental mercury was measured using a light detection and ranging (LIDAR) technique. From vertical LIDAR sweeps through the plume from the chlor-alkali plant mercury emission rates could be calculated. The concentrations of reactive gaseous mercury (RGM) in the plume and also inside the cell house were measured using annular KCl coated denuders. The RGM emission constitutes 0.5-1.0% of the total mercury emitted from the plant. The mercury concentration adsorbed on particles was measured as well as the mercury flux from soil. The data presented also include an intercomparison showing an excellent agreement between TEKRAN/GARDIS and LIDAR gaseous mercury measurements.

Air Pollutants↗
PubMed2003

Improvement of organoleptic quality of retted cassava products by alkali pretreatment of roots and addition of sodium nitrate during retting.

Alkali pretreatment of cassava roots before retting and addition of sodium nitrate during retting were used to manipulate the metabolism of microorganisms involved in cassava (Manihot esculenta Crantz) retting, as a method for removing the characteristic offensive odour of retted cassava products. Odour was assessed by organoleptic methods. The characteristics of fermentation of cassava by the traditional method (control) were as follows; aerobic mesophilic count (APC) on nutrient agar (NA) at 30 degrees C/48 h, attained a maximum of 2.3 x 10(7)/ml retting juice while counts on de Man Rogosa and Sharpe agar (MRS) at 30 degrees C/48 h were 1.6 x 10(8)/ml. Maximum titrable acidity was 0.062% lactic acid by weight of retting juice. Cassava was retted in 3 days and the product exhibited characteristic offensive odour. Addition of NaNO3 into retting water effectively removed odour at a concentration of 0.3 g/l. Maximum APC on NA/30 degrees C/48 h was 6.8 x 10(6)/ml. Counts on MRS/30 degrees C/48 h exceeded 2.4 x 10(9)/ml. Retting was complete in 3 days with a final titrable acidity of 0.068% of retting juice. Removal of odour likely resulted from selection of homo-fermentative lactic acid bacteria, thus producing mostly odourless lactic acid. Alkali pretreatment of roots before retting was efficacious in removing odour at a concentration of 10 g/l for 30 min. This fermentation was characterized by APC on NA/30 degrees C/48 h of 5.4 x 10(6)/ml; MRS/30 degrees C/48 h reached a maximum of only 10 x 10(4)/ml and correspondingly low titrable acidity of 0.003%. Low counts of lactic acid bacteria correlate well with the absence of odour in this sample. Both treatments did not adversely affect the detoxification process, yielding "foo-foo" with HCN levels lower than 10 mg/kg. Residual nitrates and nitrites of 30 mg/kg in the sodium nitrate-treated sample were also within the safe limits of 156 mg/kg allowed in many countries. Organoleptically improved samples were acceptable to the public.

Colony Count, Microbial↗
PubMed1996

Rolaids-yogurt syndrome: a 1990s version of milk-alkali syndrome.

Milk-alkali syndrome is characterized by progressive hypercalcemia, systemic alkalosis, and renal insufficiency. After calcium carbonate is ingested with diary products, hypercalcemia and alkalosis may develop in susceptible persons, particularly those with underlying renal insufficiency. We describe a young woman who neither drank milk nor had peptic ulcer disease, yet who ingested enough calcium carbonate to require admission to an intensive care unit for acute renal failure. Chronically bulimic, she was taking Rolaids (Warner-Lambert Co, Morris Plains, NJ), which contained calcium carbonate, and was eating yogurt daily to prevent osteoporosis. We discuss the characteristics and complex metabolic interactions of the milk-alkali syndrome, a critical but generally reversible electrolyte disorder. Early recognition of coincident hypercalcemia and alkalosis and prompt cessation of calcium carbonate ingestion are essential for successful recovery. Finally, we suggest that nephrologists should discourage patients with renal insufficiency and chronic vomiting from consuming calcium-containing antacids and excessive dietary calcium.

Acute Kidney Injury↗
PubMed2002

Removal of mercury(II) from aqueous solutions and chlor-alkali industry effluent by steam activated and sulphurised activated carbons prepared from bagasse pith: kinetics and equilibrium studies.

The adsorption of mercury from aqueous solutions and chlor-alkali industry effluent on steam activated and sulphurised steam activated carbons prepared from bagasse pith have been studied comparatively. The uptake of mercury(II) (Hg(II)) was maximum by steam activated carbon in presence of SO(2) and H(2)S (SA-SO(2)-H(2)S-C) followed by steam activated carbon in presence of SO(2) (SA-SO(2)-C), steam activated carbon in presence of H(2)S (SA-H(2)S-C) and steam activated carbon (SA-C) at the same concentration, pH and temperature of the solution. Adsorption experiments demonstrate that the adsorption process corresponds to the pseudo-second-order kinetic model and equilibrium results correspond to the Langmuir adsorption isotherm. Kinetic parameters as a function of initial concentration, for all adsorbents were calculated. Batch studies indicated that the optimum pH range for the adsorption of Hg(II) on sulphurised carbons was between 4 and 9 and for sulphur free carbon was between 6 and 9 at 30 degrees C. The adsorptive behaviour of the activated carbons is explained on the basis of their chemical nature and porous texture. Decrease in ionic strength and increase in temperature of the solution has been found to improve the uptake of Hg(II). Synthetic and chlor-alkali industrial wastewaters were also treated by sulphurised activated carbons to demonstrate their efficiencies in removing Hg(II) from wastewaters. Some feasibility experiments have been carried out with a view to recover the adsorbed Hg(II) and regenerate the spent activated carbons using 0.2M HCl solution. The data obtained point towards viable adsorbents, which are both effective as well as economically attractive for Hg(II) removal from wastewaters.

Adsorption↗
PubMed2001

Prolonged intermittent hydrotherapy and early tangential excision in the treatment of an extensive strong alkali burn.

It is well known that the first step in the treatment of cutaneous strong alkali burn is very early and persistent washing of the site of injury with large volumes of water. However, ideal duration and the technique of hydrotherapy has not yet been established. Besides hydrotherapy, tangential excision of the injured skin might prevent further tissue damage if it is performed early enough. We report the treatment of a 36-year-old male who sustained 53% body surface area (BSA) cutaneous burn due to caustic soda (NaOH). Prolonged intermittent hydrotherapy, early tangential excision and autografting of the injured skin are the keys for the proper management of extensive strong alkali burn.

Accidents, Occupational↗
PubMed2003

Evaluation of alkali and alkaline earth metal cation selectivities of lariat ether amides by electrospray ionization mass spectrometry.

Lariat ethers with pendant amide groups have shown promise as new ion sensors because of their selectivity towards particular metal ions. In this study we report alkali and alkaline earth metal binding selectivities of dibenzo-16-crown-5 and fifteen dibenzo-16-crown-5 lariat ether amides (LEAs) as determined by electrospray ionization mass spectrometry (ESI-MS). Additionally, the influence of the acid/base nature of the solution on metal cation selectivity is investigated. The validity of using ESI-MS for determination of selectivities is established by analogous experiments using hosts with known binding constants for the same metal cations and solvent systems. Collisionally activated dissociation (CAD) is used to evaluate the influence of the alkali metal cation binding on the fragmentation of the LEAs.

Journal Article↗
PubMed2000

Absorption and emission characteristics of Er3+ ions in alkali chloroborophosphate glasses.

Alkali chloroborophosphate glasses containing 1 mol% of Er3+ ions were studied experimentally using the absorption and emission spectroscopy. The energy level scheme for the 4f11 (Er3+) electronic configuration was deduced from the observed band energies of the absorption spectra in terms of a parametrized Hamiltonian using the various free-ion spectroscopic parameters. Oscillator strengths (f) measured from the absorption spectra have been analyzed using the Judd-Ofelt theory to evaluate the three intensity parameters omegalambda (lambda = 2, 4 and 6). Reasonable agreement between the measured and calculated f values has been found. Electric and magnetic dipole transition probabilities, fluorescence branching ratios, integrated emission cross sections and radiative lifetimes were calculated for all the excited states of Er3+ ions. The non-radiative (WNR) relaxation rates from the excited levels to the next lower levels have been calculated and the relationship between the energy gap and non-radiative relaxation rate has been established. These results were used to predict the possible potential laser transitions in Er-doped alkali chloroborophosphate glasses.

Erbium↗
PubMed2002

Characterization of alkali treated flax fibres by means of FT Raman spectroscopy and environmental scanning electron microscopy.

Flax fibres grown under well managed conditions were submitted to NaOH chemical treatments, so called Mercerization. The extent of the polymorphic transformation of cellulose I into cellulose II taking place within the crystalline domains of the fibre cellulose was dependent on the alkali concentration. FT Raman spectroscopy turned out to represent an ideal tool for detecting the polymorphic transformation of the cellulosic fine structure of the flax fibres in vivo. In addition to the differences of the FT Raman spectra in the frequency range below 1500 cm(-1), second derivatives of the spectra in the range of the CH stretching vibrations could also be used to distinguish the two polymorphic modifications. The intensity ratio R of the stretching modes v(s)COC and v(as)COC represents a spectral parameter characterising the molecular structure of the flax fibres. As a supplementary tool, Environmental scanning electron microscopy (ESEM) was used to visualize the microstructural fibre properties dependent on the alkali concentrations during the Mercerization.

Cellulose↗