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Showing papers on "Zinc published in 1969"



Journal ArticleDOI
TL;DR: The absorption of zinc has been studied in the brown seaweed Laminaria digitata (Huds.) Lamour.
Abstract: The absorption of zinc has been studied in the brown seaweed Laminaria digitata (Huds.) Lamour., with use of the radionuclide 65Zn and atomic absorption analysis. No evidence of the regulation of zinc by the plant has been found. Absorption of zinc or 65Zn is a gradual process of accumulation which may continue throughout the life of the plant and is not accompanied by the exchange of zinc. As a result, once it has been absorbed, zinc or 65Zn shows little tendency to be lost from the plant. The amounts of zinc or 65Zn which can be accumulated from sea water containing different concentrations of zinc and the effects on these of growth, light and competition from other metals have been studied. Possible sites at which zinc might be bound have been discussed, and the experimental results have been compared with the situation found in the field.

184 citations


Journal ArticleDOI
TL;DR: In this article, two sets of experiments were carried out to obtain a better understanding of the tendency of the alkaline zinc electrode to passivate either photomicrographs of the electrode surface were taken in situ at different potentials during an anodic voltage sweep or the two components of electrode impedance were measured with a small signal of superimposed 1000 Hz AC.
Abstract: In this study, mainly two sets of experiments were carried out to obtain a better understanding of the tendency of the alkaline zinc electrode to passivate Either photomicrographs of the electrode surface were taken in‐situ at different potentials during an anodic voltage sweep or the two components of the electrode impedance were measured with a small signal of superimposed 1000 Hz AC The course of the passivation was found to depend strongly on the convective conditions in the electrolyte near the zinc electrode The conditions for the formation of two different types of solid films have been defined and their effects on the current‐potential curve have been determined Type I film is white, loose, and flocculent It forms in the absence of convection by precipitation from a supersaturated layer of zincate near the surface When the conditions for supersaturation are largely removed by stirring, the formation of the type II film can be observed The latter is more compact and appears to form directly at the surface rather than by precipitation Its color can range from light gray to black depending on the potential and time of formation The type II film is considered responsible for the transition from the active to the passive state of zinc in alkaline solution

147 citations




Journal ArticleDOI
21 Nov 1969-Science
TL;DR: The 12-day-old embryos of rats with a deficiency of zinc showed a reduced uptake of tritiated thymidine when compared with controls, as shown by liquid scintillation and autoradiography.
Abstract: The 12-day-old embryos of rats with a deficiency of zinc showed a reduced uptake of tritiated thymidine when compared with controls, as shown by liquid scintillation and autoradiography. The high incidence of gross congenital malformations resulting from zinc deficiency may thus be caused by DNA impaired DNA synthesis.

117 citations



Journal ArticleDOI
TL;DR: NENE was the first to show that a foliar application of zinc sulfate corrects a disorder of the rice plant long known as Khaira disease in North-Central India.
Abstract: Until very recently zinc deficiency of the rice plant had not been shown to occur in the field. Y. L. NENE (1) was the first to show that a foliar application of zinc sulfate corrects a disorder of the rice plant long known as Khaira disease in North-Central India.

114 citations


Journal ArticleDOI
TL;DR: A single injection of 100 μg of zinc was sufficient to rapidly reverse the effect of zinc deficiency on the synthesis of DNA in the rat.
Abstract: Dietary zinc deficiency has been shown to decrease the in vivo incorporation of thymidine into the nuclear DNA of liver parenchymal cells in the rat. A single injection of 100 μg of zinc was sufficient to rapidly reverse the effect of zinc deficiency on the synthesis of DNA.

108 citations


Journal ArticleDOI
TL;DR: It was concluded that a dietary zinc intake of 17.4 p.p.m. is adequate for growth of ram lambs but is inadequate for normal testicular development and function.
Abstract: Ram lambs fed on a diet containing 2.4 p.p.m. zinc made poor growth, developed clinical signs of severe zinc deficiency, showed impaired testicular growth, and showed a complete cessation of spermatogenesis within a period of 20–24 weeks. Lambs fed on the same diet supplemented with zinc sulphate to provide total zinc levels of 17.4 and 32.4 p.p.m. had a higher feed intake, made significantly greater liveweight gains, and showed no signs of zinc deficiency. Testicular growth and sperm production were markedly improved by both the zinc supplements. No differences in liveweight gains or feed consumption between the two supplemented groups were observed but testicular growth and sperm production were highly significantly greater in the lambs receiving the larger zinc supplement. It was concluded that a dietary zinc intake of 17.4 p.p.m. is adequate for growth of ram lambs but is inadequate for normal testicular development and function. Lambs in which consumption of the diet containing 32.4 p.p.m. zinc was restricted to that of the zinc-deficient group showed no significant improvement in liveweight gains, but testicular development and sperm production were significantly greater than in the zinc-deficient lambs. Complete remission of all signs of zinc deficiency and full recovery of testicular size, structure, and function were achieved in a zinc repletion period lasting 20 weeks.

100 citations




Journal ArticleDOI
TL;DR: Methods for the determination of zinc in plasma diluted twenty-fold with 0.1 N HCl, in whole blood diluted one hundred times and urine diluted tenfold, using a Perkin-Elmer 303 atomic absorption spectrophotometer found that Random contamination presents a problem which was best detected by replicate analysis.


Journal ArticleDOI
TL;DR: The data suggest that leucine aminopeptidase is a zinc metalloenzyme, and that replacement of the cadmium in Cadmium leucINE aminopesidase by zinc restores native levels of activity.

Journal ArticleDOI
TL;DR: In this article, the EDTA titration was used for the determination of the metal in organic compounds containing calcium, magnesium, zinc, barium, manganese, or cobalt.

Journal ArticleDOI
TL;DR: In this article, the rate of zinc uptake, the effects of carrier ions, temperature, light intensity and dinitrophenol (DNP) upon the uptake of zinc (using zinc-65 as tracer) by Fontinalis antipyretica were investigated.
Abstract: The rate of uptake, the effects of carrier ions, temperature, light intensity and dinitrophenol (DNP) upon the uptake of zinc (using zinc-65 as tracer) by Fontinalis antipyretica were investigated. The absorption medium contained 0.5 mW CaSO4 and the pH was kept constant using boric acid and sodium hydroxide as buffer. About 50 per cent of the zinc absorbed at equilibrium was taken up in the first half hour, Analysis by semi-log plot procedures showed that, at least, three sections may be distinguished in the uptake curve, suggesting that three successive processes (stages) were involved. The first stage was very short, and not influenced by temperature, light intensity and DNP. The second stage, lasting no more than 90 minutes, mi very slightly affected by the same three factors. In this stage freshly killed plants absorb more zinc than living material. The third stage, lasting several days, was very slow and was light, temperature and DNP dependent. Based on these findings, a mechanism for zinc uptake is proposed.

Journal ArticleDOI
TL;DR: The optical rotatory dispersion spectra of these different metallophosphatases are very similar between 25° and 55° suggesting little change in protein structure, but only Co2+ and Zn2+ alkaline phosphatase are active enzymes.
Abstract: The alkaline phosphatase of Escherichia coli is a zinc metalloprotein with a metal to enzyme ratio of 4. Inorganic phosphate protects the four zinc atoms against removal by EDTA. Cadmium and manganese can replace zinc on its four binding sites. Samples of phosphatase with different proportions of zinc and cadmium or of zinc and manganese have been prepared and tested for their enzymatic activity. These results together with others suggest a model which involves two functional and two structural zinc atoms. The zinc atoms necessary for the activity would have different apparent binding constants for the apoenzyme. This conclusion is in agreement with Cohen and Wilson's scheme postulated in 1966. Dissociation constants for Me2+-apophosphatase complexes were determined (Me2+= Zn2+, Ni2+, Cd2+, Co2+, Mn2+). These constants follow the order Ni2+ > Co2+ > Zn2+ > Cd2+= Mn2+. The optical rotatory dispersion spectra of these different metallophosphatases are very similar between 25° and 55° suggesting little change in protein structure. However, only Co2+ and Zn2+ alkaline phosphatases are active enzymes.


Journal ArticleDOI
TL;DR: In this paper, the thermal properties of the cobalt, nickel, copper, zinc, and cadmium-II complexes of diethyldithiocarbamic acid were determined by TG, DTA, and high temperature reflectance spectroscopy.
Abstract: The cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and mercury(II) complexes of diethyldithiocarbamic acid were prepared and their thermal properties determined by TG, DTA, and high temperature reflectance spectroscopy. It was found that the copper(II), nickel(II), and zinc(II) chelates were completely volatile and thus represent a new class of volatile metal chelates. Vapor pressure measurements were made on four of the metal complexes; heats of vaporization ranged from 9.3±0.2 kcal/mole for Na[Co(DDC)3] to 24.2±0.6 kcal/mole for Zn(DDC)2.

Journal ArticleDOI
TL;DR: In this paper, the same authors showed that Ni(IV) flow spin d6) is surrounded by 6 S atoms in octahedral symmetry, and they obtained diamagnetic and diamagnetic diamagnetic oxide complexes of composition [Ni(bu2dtc)3]X.
Abstract: Oxidation of N,N-di-n-butyldithiocarbamato (bu2dtc) complexes of Cu(I), Ni(II), Zn(II), Cd(II) and Hg(II) is reported. Oxidation of Ni(bu2dtc)2 with Cl2, Br2, or of NiX2 (X = Cl, Br, NO3) with N,N,N′,N′-tetra-n-butylthiuram disulfide (bu4tds) gives complexes of composition [Ni(bu2dtc)3]X. These compounds are diamagnetic and dissolve in nitrobenzene as 1:1 electrolytes, their UV spectra resemble that of the iso-electronic Co(bu2dtc)3. The experimental data are in accord with the assumption that in these compounds Ni(IV) flow spin d6) is surrounded by 6 S atoms in octahedral symmetry. The analogous selenium compound tris (N, N-di-n-butyldiselenocarbamato) nickel(IV) bromide, having the same properties as the thio compounds, can also be prepared. Oxidation of Cu(bu2dtc) with Cl2 or Br2 yields paramagnetic products with the composition CuX3(bu2dtc), in which Cu also has the formal oxidation number + 4, but the structure of these compounds is still obscure. Oxidation of Zn(bu2dtc)2 and the corresponding Cd and Hg compounds yields products, the analysis of which suggests the composition MX2(bu2dtc)2 (M = Zn, Cd or Hg, X = Br or I), but infrared studies indicate that the dithiocarbamato ligands of the starting substances are oxidized to bu4tds, which in the reaction products is coordinated to the metal in its normal oxidation state + 2.

Journal ArticleDOI
TL;DR: In this article, dual ac Hall effect measurements of the chemisorption of oxygen on gallium-doped zinc oxide have shown that oxygen is mainly O 2 − between 100 ° and about 180 °C, and as O − above about 230 °C.

Journal ArticleDOI
TL;DR: In this paper, the effect of flowing electrolyte on the morphology of zinc electrode-posited from aqueous alkaline solution has been investigated, and the results showed that flowing electrolytes under both turbulent flow and laminar flow conditions greatly modified the deposit morphologies.
Abstract: The effect of flowing electrolyte on the morphology of zinc electrode‐posited from aqueous alkaline solution has been investigated. Aqueous potassium hydroxide solution of 5.8N normality containing 19.1 g/dm3 of dissolved zinc oxide was circulated through a flow tube at flow velocities up to 1.7 m/s, corresponding to Reynold's numbers of up to 13,500. The morphologies of zinc electrodeposits formed on a zinc substrate in the wall of the flow tube were examined over a range of current densities and Reynold's numbers. The results showed that flowing electrolyte under both turbulent flow and laminar flow conditions greatly modified the deposit morphologies. It was possible to construct a morphology, current density, and Reynold's number "phase diagram" to describe the effects of flowing electrolyte on deposit morphology.

Patent
26 Jun 1969
TL;DR: In this article, the authors used a combination of a SURGICAL GRADE ZINC OXIDE POWDER with an AQUEOUS solution of POLYACrylIC ACID to give a plastic mass that resisted hardening.
Abstract: DENTAL CEMENTS ARE PREPARED BY MIXING A SURGICAL GRADE ZINC OXIDE POWDER WITH AN AQUEOUS SOLUTION OF POLYACRYLIC ACID TO GIVE A PLASTIC MASS THAT RAPIDLY HARDENS. TYPICAL SOLUTIONS CONTAINS ABOUT 42% BY WEIGHT POLYACRYLIC ACID HAVING A VISCOSITY DETERMINED MOLECULAR WEIGHT OF ABOUT 25,000 OR ABOUT 55,000 TO 80,000. THE CEMENTS HAVE GREATER ADHESION AND CAUSE LESS IRRITATION THAN CONVENTIONAL ZINC PHOSPHATE CEMENTS.

Journal ArticleDOI
TL;DR: Neutron activation analysis was used for the simultaneous determination of copper, manganese and zinc in the brains of calves, cows and pigs and showed that the highest content is always found in the pineal body.
Abstract: — Neutron activation analysis was used for the simultaneous determination of copper, manganese and zinc in the brains of calves, cows and pigs. Measurements of these three elements in as many as 11 different regions of the brain showed that the highest content is always found in the pineal body. Typical values for calf brains are: Cu, ∼20 μg/g; Mn, ∼3 μg/g; and Zn, ∼90 μg/g dry pineal tissue. As a first approximation, the ratio of Cu:Mn:Zn is roughly constant for all regions.

Journal ArticleDOI
TL;DR: It is proposed that cobalt and zine function at the active site for pyruvate because radioactivity of 60Co-labeled transcarboxylase is primarily associated with a subunit of the enzyme with a sedimentation constant of 6S that contains little or no biotin.



Journal ArticleDOI
TL;DR: In this article, the coordination properties of terpyridyl complexes of mercury(II)halides, perchlorates and nitrates are compared with their zinc and cadmium analogs.

Journal ArticleDOI
TL;DR: The high values of the binding constants, and the fact that denaturation destroys the specific binding of zinc to alkaline phosphatase indicates chelate formation with the protein, unless some unknown prosthetic groups are involved.
Abstract: The binding of Zn2+ to Escherichia coli alkaline phosphatase has been studied by pH titrations and equilibrium dialysis using 1,10-phenanthroline as competing chelating agent. Measurements of the strength of binding under different experimental conditions have been performed: 1 At constant pH with different concentrations of chelating agent. 2 At different pH with constant concentration of chelating agent. 3 In the presence of denaturing agent at pH 8.0. It was found on the basis of equilibrium dialysis experiments that the binding of the two zinc atoms to alkaline phosphatase may be described as coordination to the two equivalent and independent sites. The high values of the binding constants, and the fact that denaturation destroys the specific binding of zinc to alkaline phosphatase indicates chelate formation with the protein, unless some unknown prosthetic groups are involved.