Addition Of AgNO3 Research Articles

Ligand exchange reactions starting from [Re(CO)3Br3]2−. Synthesis, characterization and structures of rhenium(I) tricarbonyl complexes with thiourea and thiourea derivatives

The anionic rhenium(I) complex fac-[Re(CO)3Br3]2− has been reacted with thiourea (tu), N,N-dialkylbenzoylthioureas (HR2btu) and N,N-dialkylthiocarbamoylbenzamidines (HR12tcbR2) to give novel mono- and binuclear rhenium(I) complexes. All new compounds are air-stable and non-sensitive against aqueous media. Fac-[Re(CO)3(tu)3] (NO3) is formed from the bromo complex by precipitation of AgBr after addition of AgNO3 and subsequent reaction with thiourea. The compound co-crystallizes with one molecule of (Et4N) NO3 in the monoclinic space group P21/n,a = 143675(3), b = 13.372(1), c = 28.841 (7) Å, ß = 102.53(1)°, Z = 8. The mean ReS bond length is 2.529 Å. N,N-Dialkylbenzoylthioureas react with (Et4N)2[Re(CO)3)Br3] to form neutral [Re(CO)3Br(HR2btu)] complexes. With the rhenium(I) centers under study they coordinate bidentately, but without deprotonation, which is unusual for this class of chelate ligands. [Re(CO)3Br(HEt2btu)] crystallizes in the triclinic space group P1, a = 8.080(2), b = 9.254(3), c = 13.761(5) Åα = 76.60(2), ß = 88.66(2), γ = 70.92(3)°, Z = 2. The chelate ring shows significant deviations from planarity which underline the absence of an extended π-system. Complexes of different composition are formed with thiocarbamoylbenzamidines depending on the sterical requirements of the individual ligands. A binuclear compound could be isolated with N,N-diethylthiocarbamoylbenzamidinate (Et2tcbH−). [Re2(CO)6−(Et2tcbH)2] crystallizes in the monoclinic space group P21/c, a = 10.859(4), b = 17.409(2), c = 9.159(5) Å, ß = 79.15(2)°, Z = 2. Both rhenium atoms are coordinated by three facially arranged carbonyls and a singly deprotonated Et2tcbH− ligand. The sulfur atoms of these ligands act as bridges between the metal centers forming a four-membered Re2S2 ring. Two slightly different ReS bond lengths are observed in this ring system (2.507(2) and 2.545(2) Å). Only a mononuclear, anionic complex is formed with the more bulky benzamidine ligand N(N-morpholinylthiocarbonyl)-N′-phenylbenzamidine (Hmorphtcbph). (Et4N) [Re(CO)3Br(morphtcbph)] crystallizes in the triclinic space group P1, a = 10.018(4), b = 10.065(4), c = 16.720(7) Å, α = 80.90(3), ß = 79.82(3), γ = 70.81(4)°, Z = 2. The rheniumsulfur distance is 2.476(2) Å.

Characterization of YBa2Cu3O7- delta single crystals grown from charges containing silver nitrate

Single-crystal growth of YBa2Cu3O7- delta has been studied using starting charges containing known amounts of Ag in the form of AgNO3. The as-grown crystals are found to undergo a sharp transition to the superconducting state at 90 K, showing that the addition of AgNO3 facilitates their oxygenation. The measured room-temperature resistivities, both in plane ( rho ab) and out of plane ( rho c), for the grown crystals are found to be the lowest among the values reported so far. The anisotropy in resistivity ( rho c/ rho ab) at 300 K is found to be roughly one-half of the value measured for the crystals grown from charges free from AgNO3. The angular dependence of transport critical current for the doped crystals has been measured at 82 K and for an applied magnetic field of 0.9 T. The results have been analysed using the existing theoretical models.

Durum wheat haploid production using maize wide-crossing

While anther culture or pollinations with Hordeum bulbosum have provided suitable methods for haploid production in bread wheat, they have been largely unsuccessful in durum wheat. Pollinations with maize were used in an attempt to produce haploid seedlings and, from these, fertile doubled haploids of durum wheats. Moreover, the effect of various concentrations and combinations of a synthetic auxin, 2, 4-dichlorophenoxyacetic acid (2,4-D), kinetin, and an ethylene inhibitor, silver nitrate (AgNO3), on embryo recovery were also investigated. Haploid seedlings were recovered from Triticum turgidum ssp. turgidum cv 'Rampton Rivet' pollinated with maize following in-vivo treatment of ovaries with 2,4-D for 2 weeks and subsequent embryo culture. The recovery of haploid seedlings from T. turgidum ssp. durum cv. 'Wakona' pollinated with maize necessitated the addition of AgNO3, to the 2,4-D treatment. Overall, haploid seedlings were produced in 1.7% and 3.3% of pollinated florets for "Rampton Rivet" and "Wakona" respectively. The success of the present work represents a significant breakthrough for haploid production in durum wheats. Wide hybridization with maize followed by in-vivo treatment of ovaries with 2,4-D alone, or in combination with AgNO3, may provide a widely-applicable method of haploid production in tetraploid wheats.

Regeneration of plantlets from embryogenic suspension cultures of pickling cucumber (Cucumis Sativus L. CV. Endeavor)

Procedures have been developed for the initiation and long-term maintenance of embryogenic suspension cultures of pickling cucumber (Cucumis sativus) cultivar Endeavor and for the regeneration of normal plantlets. Embryogenic calluses from petiole explants plated on Murashige and Skoog (MS) medium with 2,4-dichlorophenoxyacetic acid (2,4-D) and 6-benzylaminopurine (BA), both at 5µM, were used to initiate the embryogenic suspension cultures. Among various growth regulator combinations evaluated for initiation and maintenance of these suspension cultures, only MS medium with 2,4-D and BA, both at 1µM, produced cultures that were yellow, friable, and still regenerable after repeated subculture (every two wk) over a 3- to 15-mo. period. The effects of various concentrations of auxin and cytokinin in the plating medium, the addition of AgNO3, and various plating procedures were also evaluated. The highest frequency of regeneration of shoots and plantlets was achieved by plating aggregates onto filter paper overlaid on MS medium with naphthalene acetic acid (NAA)/BA at a concentration of 2:1 or 1:1µM. The addition of activated charcoal (0.5%) or AgNO3 (30µM) in the plating medium did not enhance the frequency of plantlet regeneration. The highest frequency of normal-appearing plantlets recovered was 42 to 46% per petri dish. The procedures described in this study can be used to increase plantlet recovery from individual embryogenic calluses of pickling cucumber.

Induction period of the crystallization of silver nitrate solutions in ethylene glycol

The dependence of the induction period of crystallization on supercooling was examined for the silver nitrate-ethylene glycol system over the concentration region of silver nitrate lome fraction of 0 to 0.12. Addition of AgNO3 to ethylene glycol was found to increase considerably the critical induction period of crystallization, although to a lesser extent than Ca(NO3)2, CaCl2, ZnCl2, LiCl and LiNO3 do. The effect of these salts on the critical induction period of crystallization in dimethylsulfoxide, dimethylformamide, dimethylacetamide and methanol was compared in terms of the solvent-rich composition limit of the glass-forming ability. By using the TTT(Time-Temperature-Transformation) theory, it has been deduced that the effect of the salts on the critical induction period of crystallization of ethylene glycol is probably due to the different dependences of viscosity on their concentration in ethylene glyco in the supercooling region.

The uptake of silver ions by Escherichia coli K12: toxic effects and interaction with copper ions

Growth of Escherichia coli in chloridefree medium in batch culture is inhibited completely at concentrations of AgNO3 greater than 2.5x10-6 M. Incubation of non-growing cells in HEPES buffer (pH 7.4) at increasing levels of Ag+ results in the progressive saturation of two types of binding site. At one site, the Ag+ is not released by washing with 0.1 M nitric acid, and is probably intracellular. Silver bound to the second site is released by acid-washing, but not by buffer washing, and is assumed to be surface-bound. The amounts of Ag+ taken up from solution at the two sites is 1.6x10-7 and 4.6x10-7 mol (mg dry weight)-1, respectively. Total accumulation of silver is 67 mg (g dry weight)-1, similar to literature values found for silver-resistant bacteria. Binding of Ag+ at intracellular sites (observed at low [Ag+]) appears to be independent of pH. Addition of AgNO3 to growing cells in mid-exponential phase of growth in concentrations that will inhibit growth results in substantially decreased accumulation of silver. Growth yield in chemostat culture is diminished in the presence of added Ag+, but this effect is moderated by added Cu2+, which may protect copper sites from Ag+ or compete with Ag+ for other sites at which Ag+ exerts toxic effects. Very small amounts of Cu2+ are found in cell samples from the chemostat compared to the substantial amounts of Ag+ taken up, but uptake of Cu2+ is decreased at higher [Ag+]/[Cu2+]ratios.

The influence of the addition of electrolytes on the degree of dispersion of silver iodide hydrosol

The changes in the degree of dispersion of AgI hydrosols produced by reaction of AgNO3 and KI with the addition of other electrolytes (1–60 min after addition of AgNO3 to KI) were investigated by photometric methods. The results obtained suggest that in the process of rapid condensation (caused by a sudden increase in concentration to a value considerably higher than the critical one) colloidal particles do not form by continuous growth of individual nuclei but through disaggregation of loose and amorphous, i. e. thermodynamically unstable clusters of previously formed embryos. This disaggregation process, termed protopeptization by the authors in order to underline its analogy with the peptization process, increases in magnitude with the strengthening adsorption of potential-determining ions (protopeptizing agents) by the particles formed in the precipitation process.

Investigations on the Water Pollution Index. II. On the Abnormal Masking Effect on Chloride Ions by Silver Nitrate in the Determination of Chemical Oxygen Demand with Potassium Permanganate

Masking effect on chemical oxygen demand (COD) values to chloride ions by silver salts was investigated by using semimicro acidic high-temperature permanganate method. Chloride ions react with permanganate, but the reaction was incomplete and the COD showed larger values after 60 min heating than 30 min. In the blank test, oxygen demand by chloride ions was masked with AgNO3 added near to the equivalent amount. Chemical oxygen demand of glucose and p-hydroxybenzoic acid was almost unaffected with increasing addition of silver salts when chloride ion was absent, and these substances were used as examples of organic substances. When chloride ions were masked with AgNO8 in the presence of glucose or p-hydroxybenzoic acid, the decrease of COD values was recognized at the near equivalent point of Cl- and silver. As a reason of the decrease, NO-3 ion, increased by the addition of AgNO3, affected the end point of titration with 0.025N KMnO4 in the presence of AgCl precipitate and produced a difficulty in recognition of pale reddish color of KMnO4. This decreasing effect on COD values was completely diminished by the further addition of definite amount of silver salts, but moderate amount of excess AgNO3 necessary for COD determination in the presence of chloride ions will be investigated in the following experiments.

Effects of Ag+ on ion transport by the corneal epithelium of the rabbit.

Exposure of the in vitro rabbit corneal epithelium to Ag+ by the addition of AgNO3 (10(-7)-10(-5) M) to the apical surface or by the use of imperfectly chlorided Ag/AgCl half-cells in Ussing-style membrane chambers, greatly increases short-circuit current and transepithelial potential. The early phase (the first 30 min) of the short-circuit current stimulation by Ag+ is linearly dependent on tear-side sodium concentration, is largely a result of a tenfold increase in net Na+ uptake and is incompletely inhibited by ouabain, suggesting that Ag+ increases cation (primarily Na+) conductance of the apical membrane. This mechanism for the Ag+ effect is supported by microelectrode experiments, wherein Ag+ depolarizes specifically the apical barrier potential and increases apical barrier conductance. A later phase in the effect (0.5-3 hr) is characterized by a gradual increase in 36Cl- and 14C-mannitol unidirectional fluxes, by a decline in epithelial resting potential and short-circuit current, by complete ouabain inhibition and by fit to saturation kinetics with respect to Na+ concentration in the bathing media. This phase of the effect apparently reflects a nonselective opening of the paracellular pathway in the epithelium and is rate-limited by Na+ pump activity at the basolateral membrane. Both phases are associated with swelling of the corneal stroma and may be rapidly reversed using thiol agents (reduced glutathione and dithiothreitol). The results suggest that Ag+ may be useful in the study of cation transport by epithelia and the work provides basic physiological information that is pertinent to the prophylactic use of AgNO3 in clinical ophthalmology.

A Growth Factor in Corpus Luteum Powder for Goitrogen-fed Rats

When a commercial preparation of corpus luteum powder was included in the diet, it reinstated growth of growth-arrested, sulfaguanidine-fed rats. A study was made, therefore, to determine whether the growth response to corpus luteum powder was due to thyroid hormones. The corpus luteum powder was hydrolyzed with acid. The acid-insoluble residue was extracted with alcohol and the addition of AgNO3 produced a precipitate which contained a growth factor capable of reinstating growth of growth-arrested, sulfaguanidine-fed and of thyroidectomized rats. One microgram of 3,5,3′-triiodo-L-thyronine produced the same growth response as 3.3 mg of the growth factor preparation. No iodine could be detected on paper chromatograms of the growth factor and the growth factor differed from triiodothyronine in its ability to prevent goiter. Two enzymes were used to compare the growth factor with triiodothyronine. Inosine monophosphate dehydrogenase was inhibited by 10-9M triiodo-L-thyronine but the growth factor had no effect on this enzyme. Adenylosuccinate synthetase was stimulated by 10-9M triiodo-L-thyronine, whereas the growth factor inhibited this enzyme. These results are taken as evidence that corpus luteum contains a growth factor which is capable of substituting for thyroid hormones insofar as growth is concerned but the growth factor is not an iodinated thyronine.

青化法によるニッケルの定量について

The cyanide titration method, which permits the volumetric estimation of nickel with speed and accuracy, depends upon the fact that nickel ions react with KCN in slightly ammoniacal solution, to form a complex anion Ni(CN)4−− with AgI as an indicator,(This article is not displayable. Please see full text pdf.) In the volumetric estimation of Ni by cyanide method, the author found that the amount of ammonia to be added and that of AgI due to the addition of AgNO3 in the solution are of vital importance to ensure the successful titration. In studying the cyanide titration, the author get following conclusions:(1) In the case of comparatively small addition of AgNO3, i.e. small amount of AgI which serves as an indicator, great excess of ammonia should be avoided strictly, for in the reaction(This article is not displayable. Please see full text pdf.) the excess of ammonia hinders the above reaction: it results in attaining, to high concentration of KCN which reacts with AgI before the nickel ammonium ions are quantitatively titrated with KCN. It gives, therefore, incorrect results.(2) In the presence of considerable amount of AgI in the solution due to the addition of about 5 cc of AgNO3, the excess ammonia does no harm, for the reaction seems to proceed in the different way, thus,(This article is not displayable. Please see full text pdf.) The reaction seems to proceed effectively, since one of the products goes away from the equilibrium, i.e. AgNO3 reacts with KI to form insoluble AgI as is shown by the formula, provided that the solution contains some amount of KI.(3) AgI serves, therefore, not only as an indicator, but also plays an important rôle in carrying out the titration in the presence of excess ammonia.(4) The safe plan to perform the titration proposed by the author consists in adding considerable amount of AgNO3 to the solution previous to the titration with KCN. The recommended practice is as follows: neutralize nitric acid solution of Ni with ammonia, methyl orange as an indicator. Add 10 cc of 10% KI solution, followed by the addition of 5 cc of standard AgNO3 solution (5 g/L). The solution is then titrated with standard KCN solution and proceeded as usual. If, by chance, some excess of ammonia is happened to be added in process of neutralization, it does no harm in the presence of considerable amount of AgI as is already explained.