scholarly journals Comparison in effect of different metal ions, pH and reducing agent on the protease activity in human hyper mature and mature cataract

2007 ◽  
Vol 8 (8) ◽  
pp. 599-603 ◽  
Author(s):  
Amtul Jamil Sami ◽  
Amtul Naseer Sami ◽  
Noreen Kanwal
Keyword(s):  
Metal Ions ◽  
Protease Activity ◽  
Reducing Agent ◽  
Mature Cataract

scholarly journals Effects of zinc and other metal ions on the stability and activity of Escherichia coli alkaline phosphatase

1971 ◽  
Vol 124 (1) ◽  
pp. 25-30 ◽  
Author(s):  
C. N. A. Trotman ◽  
C. Greenwood
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Metal Ions ◽  
Phosphatase Activity ◽  
Structural Stability ◽  
Zinc Content ◽  
Sedimentation Velocity ◽  
Reducing Agent ◽  
Deficient Mutant ◽  
The Stability

Measurement of the ultraviolet circular dichroism of apo-(alkaline phosphatase) in urea solutions showed substantial denaturation in 3m-urea. A zinc-deficient mutant alkaline phosphatase behaved similarly. The stability of the enzyme in 6m-urea was followed as a function of its zinc content and was found to be dependent on the first two of the four zinc atoms bound by apoenzyme. Phosphatase activity was mostly dependent on a second pair of zinc atoms. Mn2+, Co2+, Cu2+ or Cd2+ also restored structural stability. Sedimentation-velocity and -equilibrium experiments revealed that dissociation of the dimer accompanied apoenzyme denaturation in urea concentrations of 1m or higher, without treatment with disulphide-reducing agent.

scholarly journals Protease-producing microorganisms inhabiting salted fish (Moloha) with special reference to protease activity of Bacillus subtilis

2014 ◽  
Vol 63 (3-4) ◽  
pp. 303-307 ◽  
Author(s):  
M. H. Abd-Alla ◽  
S. A. Omar ◽  
M. A. El-Nagdy
Keyword(s):  
Bacillus Subtilis ◽  
Salt Tolerance ◽  
Metal Ions ◽  
Special Reference ◽  
Protease Activity ◽  
Enzyme Production ◽  
Effect Of Temperature ◽  
Protease Production ◽  
Salted Fish ◽  
Tanning Industry

The investigation was designed to isolate and identify the proteolytic microorganisms inhabiting salted fish. <i>Bacillus subtilis</i> was chosen as the most promising protease producer. Some properties of the crude protease are presented, the effect of metal ions on protease production has been studied. It was shown that Ca<sup>2+</sup> and Mg<sup>2+</sup> stimulated, while Co<sup>2+</sup> , Zn<sup>2+</sup> and Cu<sup>2+</sup> inhibited the enzyme production. The effect of temperature and pH and salt tolerance have also been studied. Protease activity was stable in 25% NaCl. The favourable characteristics of the enzyme might have extensive application in laundry detergents and in tanning industry.

scholarly journals STUDI OPTIMASI PENENTUAN UNSUR HARA BESI DALAM CAMPURAN TANAH DAN KOMPOS MENGGUNAKAN METODE SPEKTROFOTOMETRI

2015 ◽  
Vol 8 (2) ◽  
pp. 143
Author(s):  
Refilda ◽  
Suhartini ◽  
Indrawati
Keyword(s):  
Citric Acid ◽  
Metal Ions ◽  
Spectrophotometric Method ◽  
Incubation Time ◽  
Iron Content ◽  
Nutrient Content ◽  
Reducing Agent ◽  
Regression Equation ◽  
Complex Stability

Determination of iron nutrient content in a mixture of soil and compost with spectrophotometric method has been carried out. Metal ions Fe(II) complexed with 0.1% ortho-fenantrolin 2 mL, 0.01 M citric acid as reducing  agent  using acetat buffer at pH 4.5 and its complex was measured by using spectrophotometer UV/Vis at wavelength 515 nm, the complex stability for was 60 minutes . The highest nutrient of iron with content in soil:compost with ratio of 0.8:0.2 was 0.92% at incubation time 30 days. The lowest iron content in the mixture of soil:compost (1:0) at incubation time for  15 days was 0.58% that obtained by the regression equation y = 95.85x + 0.025 with R2=0.992. The level of nutrient iron in compost obtained lower than the maximum regulated by SNI 2.00%.

Rheological Monitoring of the Formation of Polyacrylamide/Cr+3 Gels

1983 ◽  
Vol 23 (05) ◽  
pp. 804-808 ◽  
Author(s):  
Robert K. Prud&apos;homme ◽  
Jonathan T. Uhl ◽  
John P. Poinsatte
Keyword(s):  
Metal Ions ◽  
Storage Modulus ◽  
Shear Viscosity ◽  
Polymer Concentration ◽  
Gelation Time ◽  
Three Dimensional ◽  
Reducing Agent ◽  
Chromium Ion ◽  
Kinetics Of

Abstract The formation of polyacrylamide/chromium-ion gels has been followed rheologically. The time dependence of the storage modulus has been used to analyze the kinetics of the gelation process. The kinetic theory of rubber elasticity has been used to determine the crosslink density in the gel from the measured value of the storage modulus. The effects of changing polymer, chromium ion, and reducing agent concentrations have been studied. polymer, chromium ion, and reducing agent concentrations have been studied. Introduction Water-soluble polymers of high molecular weight, such as polyacrylamides, polysaccharides, and hydroxyl ethyl celluloses, have been studied as polysaccharides, and hydroxyl ethyl celluloses, have been studied as water flooding additives since the late 1950's. These polymers are added to control fluid movement in reservoirs to improve sweep efficiencies. In addition to enhanced fluid mobility control in porous media by increased viscosities of polymer solutions, the injection of dilute (250 ppm) polyacrylamide solutions causes permeability reductions that persist after polyacrylamide solutions causes permeability reductions that persist after the mobile polymer is flushed from the pore space by water. This reduction in permeability to water is a result of the retention of polyacrylamide in the porous rock by adsorption and mechanical entrapment. Rock permeability also can be reduced deliberately by crosslinking a polyacrylamide solution in situ to form a three-dimensional (3D) gel. The polyacrylamide solution in situ to form a three-dimensional (3D) gel. The gelled polymer is capable of shutting off fractures and zones of high permeability. The rate at which this 3D gel is formed determines how far permeability. The rate at which this 3D gel is formed determines how far the solution can be pushed into the rock formation away from the injection well before gelation occurs. Polyacrylamides are known to form gels in the presence of Cr+3 ions. The process involves the reduction of Cr+6 to Cr+3 with a reducing agent such as sodium bisulfite or thiourea. When Cr+6 is reduced to Cr+3, the trivalent chromium ion and polymer react slowly to form a 3D gel structure. The mechanism by which polyacrylamide or partially hydrolyzed polyacrylamide forms gels in the presence of metal ions is not well polyacrylamide forms gels in the presence of metal ions is not well understood. One idea is that Cr+3 serves as a crosslinking agent between the polyacrylamide molecules. Another suggestion is that Cr+3 forms a stable dispersion in the polymer solution, resulting in either a highly viscous liquid or a gel. Only a limited amount of data has been published on the kinetics of the polyacrylamide/chromium ion gelation process. Terry et al. followed the increase of the steady shear viscosity with time after the introduction of a reducing agent to a polyacrylamide/Cr+6 solution. Gelation time was defined as the time required for the shear viscosity to reach an arbitrary value. The effects of varying polymer type and concentration, Cr+6 concentration, and reducing agent type and concentration were investigated. A linear relationship was found between the reciprocal of the gelation time and the reciprocal of the polymer concentration for a given polymer reducing agent system. The gelation time decreases both with increasing polymer concentration and with increasing Cr+6 and reducing agent polymer concentration and with increasing Cr+6 and reducing agent concentrations. An Arrhenius-type relationship was shown between gelation time and temperature by Willhite and Jordan. During the buildup of a 3D gel network, the shear viscosity increases, but the shearing motion imposed on the sample also tends to break down the network being formed. SPEJ p. 804

scholarly journals Bimetallic Chitosanstabilized Nanoparticles Ag/Cu, Ag/Co with Fungicidal Properties

2021 ◽  
Author(s):  
Noira Vokhidova ◽  
S. Sh. Rashidova
Keyword(s):  
Metal Ions ◽  
Growth And Development ◽  
Bimetallic Nanoparticles ◽  
Reducing Agent ◽  
Size And Shape ◽  
Molar Ratios

Abstract Synthesized chitosan stabilized bimetallic nanoparticles Ag/Cu and Ag/Co. It was found that the size and shape of bimetallic nanoparticles can be controlled by varying the concentration of the reducing agent – NaBH4 and the molar ratios of metal ions.Established that an increase in the concentration of the reducing agent, as well as metal ions, promote the formation of fibrillar nanoparticles. It was found that solutions of the synthesized samples effectively suppress the growth and development of the phytopathogen - Fusarium oxysporium forming a sterile zone from 13.3 to 36 mm.

HREM Study of electron-induced surface radiation damage in ReO3

1991 ◽  
Vol 49 ◽  
pp. 636-637
Author(s):  
R. Ai ◽  
H.-J. Fan ◽  
L. D. Marks
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Metal Oxides ◽  
Electron Irradiation ◽  
Transition Metal Oxides ◽  
Carbon Film ◽  
Transition Metal Ions ◽  
Surface Radiation ◽  
Valence Transition ◽  
Electron Microscopes

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.

ELNES of Iron Compounds

1990 ◽  
Vol 48 (2) ◽  
pp. 28-29
Author(s):  
Hiroki Kurata ◽  
Kazuhiro Nagai ◽  
Seiji Isoda ◽  
Takashi Kobayashi
Keyword(s):  
Energy Loss ◽  
Metal Ions ◽  
Energy Resolution ◽  
Transition Metal Oxides ◽  
Local Symmetry ◽  
Iron Compounds ◽  
Fine Structures ◽  
Electron Energy Loss ◽  
Fe Ions ◽  
Electron Energy Loss Spectra

Electron energy loss spectra of transition metal oxides, which show various fine structures in inner shell edges, have been extensively studied. These structures and their positions are related to the oxidation state of metal ions. In this sence an influence of anions coordinated with the metal ions is very interesting. In the present work, we have investigated the energy loss near-edge structures (ELNES) of some iron compounds, i.e. oxides, chlorides, fluorides and potassium cyanides. In these compounds, Fe ions (Fe2+ or Fe3+) are octahedrally surrounded by six ligand anions and this means that the local symmetry around each iron is almost isotropic.EELS spectra were obtained using a JEM-2000FX with a Gatan Model-666 PEELS. The energy resolution was about leV which was mainly due to the energy spread of LaB6 -filament. The threshole energies of each edges were measured using a voltage scan module which was calibrated by setting the Ni L3 peak in NiO to an energy value of 853 eV.

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