Synthesis and physico-chemical properties of diruthenium(III, II) tetra-aryl carboxylato compounds

Monochloro-tetra-μ-aryl-carboxylatodiruthenium(III, II) compounds Ru2Cl (O2CAr)4 (Ar = -C6H5; -C6H4-p-OCH3), are prepared and characterized. The compounds have magnetic moments that correspond to three unpaired spins per dimer. The Rusingle bondRu bond order is 2.5 and the ground electronic configuration is σ2π4δ2(δ*π*)3. The visible spectral band is observed at ca 450 nm along with a shoulder near 580 nm in DMF solution. The compounds undergo a one-electron Ru(III)Ru(II) → Ru(II)Ru(II) quasi-reversible reduction in DMF near 0.0 V vs sce.

Leading Sheep III

Leading Sheep is a framework for supporting decision-making about technologies and practices to increase the profitability and productivity of the Queensland Sheep Businesses. Leading Sheep aims to achieve a high level of engagement with sheep businesses in Queensland to support their ongoing decision making processes about productivity and profitability.

Biodegradation of gelatin graft copolymers. III

Gelatin-g-poly(methyl acrylate) and gelatin-g-poly(acrylonitrile) copolymers were prepared in an aqueous medium using K2S2O8 initiator. A plausible mechanism has been put forward for the observed grafting behavior of monomers. Gelatin-g-PAN showed a greater resistance to mixed bacterial inolucum compared to gelatin-g-PMA samples. The rate of degradation decreased with the increase in grafting efficiency. A parallel set of experiments carried out by employing the samples as the only source of both carbon and nitrogen showed a marginal but definite increase in the utilization of the polymer. The nitrogen analysis also showed the utilization of the polymer. Scanning electron micographs of the polymer films do show extensive pitting after microbiological testing.

Preparation, characterisation and thermal properties of hydrazinium derivatives. Part III

Hydrazinium acetate, metavanadate, sulfite, sulphamate and thiocyanate have been prepared by the reaction of corresponding ammonium salts with hydrazine hydrate. The compounds were characterised by chemical analysis and infrared spectra. Thermal behaviour of these hydrazinium derivatives have been investigated using thermogravimetry and differential thermal analysis.

Influence of deamidation(s) in the 67-74 region of ribonuclease on its refolding

The influence of chemical mutation featuring the selective conversion of asparagine or glutamine to aspartic or glutamic acid, respectively, on the kinetics of refolding of reduced RNase has been studied. The monodeamidated derivatives of RNase A, viz. RNase Aa1a, Aa1b, and Aa1c having their deamidations in the region 67-74, were found to regain nearly their original enzymatic activity. However, a marked difference in the kinetics of refolding is seen, the order of regain of enzymic activity being RNase A greater than Aa1c congruent to Aa1a greater than Aa1b. The similarities in the distinct elution positions on Amberlite XE-64, gel electrophoretic mobilities, and u.v. spectra of reoxidized and native derivatives indicated that the native structures are formed. The slower rate of reappearance of enzymic activity in the case of the monodeamidated derivatives appears to result from altered interactions in the early stages of refolding. The roles of some amino acid residues of the 67-74 region in the pathway of refolding of RNase A are discussed.

Risk assessment and preventive strategies for herbicide resistance in NR (phase III)

The threat and management of glyphosate# resistant weeds are major issues facing northern region growers. At present five weeds are confirmed glyphosate-resistant: barnyard grass, liverseed grass, windmill grass, annual ryegrass and flaxleaf fleabane. This project used 25 experiments to investigate the ecology of the grass weeds, plus new or improved chemical and non-chemical control tactics for them. The refined glyphosate resistance model developed in this project used the experiments' findings to predict the long-term impacts on evolution of resistance and on seed bank numbers of resistant weeds. These data led to revised management and resistance avoidance strategies, which were published in the Reporter newsletter, and via an on-line risk assessment tool. - See more at: http://finalreports.grdc.com.au/UQ00054#sthash.oTkCN4Sk.dpuf

Herbicide tolerance of barley and wheat cultivars in NR (phase III)

During the past 10 years, this project tested 23 barley and 51 wheat varieties with 19 and 34 registered herbicides, respectively. It concentrated on new varieties and herbicides. The research highlighted that Northern Region (NR) wheat and barley varieties differed considerably in their sensitivity to these herbicides. Overall, 9 per cent of wheat variety x herbicide combinations and 6 per cent of barley variety x herbicide combinations had significant yield losses (3 to 38%) from herbicides at recommended rates and crop stages. In addition, 21 to 23 per cent had significant yield losses from herbicides at double rates, indicating a narrow margin of crop safety.

Ternary metal complexes of anionic and neutral pyridoxine (vitamin B6) with 2,2'-bipyridine. Syntheses and x-ray structures of (pyridoxinato)bis(2,2'-bipyridyl)cobalt(III) perchlorate and chloro(2,2'-bipyridyl)(pyridoxine)copper(II) perchlorate hydrate

Ternary metal complexes involving vitamin B6 with formulas [CO",(PN-H)](anCdI [OC)'(bpy)(PN)Cl]C10(.bpHy 0 = 2,2'-bipyridine, PN = neutral pyridoxine, PN-H = anionic pyridoxine) have been prepared for the first time and characterized by means of magnetic and spectroscopic measurements. The crystal structures of the compounds have also been determined. [CO(PN-H)](CcryIsOta,l)lize s in the space group P2,/c with a = 18.900 (3) A, b = 8.764 (1) A, c = 20.041 (2) A,p = 116.05 (l)', and Z = 4 and [Cu(bpy)(PN)C1]C104-H20in the space group Pi with a = 12.136 (5) A, b = 13.283 (4) A,c = 7.195 (2) A, a = 96.91 (Z)', 0 = 91.25 (3)', y = 71.63 (3)', and Z = 2. The structures were solved by the heavy-atom method and refined by least-squares techniques to R values of 0.080 and 0.042 for 3401 and 2094 independent reflections, respectively. Both structures consist of monomeric units. The geometry around Co(II1) is octahedral and around Cu(I1) is distorted square pyramidal. In [CO(PN-H)]t(wCo IoxOy~ge)n~s ,fro m phenolic and 4-(hydroxymethyl) groups of PN-H and two nitrogens from each of two bpy's form the coordination sphere. In [Cu(bpy)(PN)C1]C104.H20o ne PN and one bpy, with the same donor sites, act as bidentate chelates in the basal plane, with a chloride ion occupying the apical position. In both structures PN and PN-H exist in the tautomeric form wherein pyridine N is protonated and phenolic 0 is deprotonated. However, a novel feature of the cobalt compound is that PN-H is anionic due to the deprotonation of the 4-(hydroxymethyl) group. The packing in both structures is governed by hydrogen bonds, and in the copper compound partial stacking of bpy's at a distance of -3.55 also adds to the stability of the system. Infrared, NMR, and ligand field spectroscopic results and magnetic measurements are interpreted in light of the structures.

Mixed ligand complexes in vinyl polymerization-II: [NN-ethylenebis(salicylideneiminato)] (benzoylacetonato)cobalt(III) as an initiator

The polymerization of methyl methacrylate initiated by a mixed ligand complex. [NN-ethylenebis(salicylideneiminato)](benzoylacetonato)cobalt(III) has been studied in bulk and in benzene at 70° and 80°. The rate of polymerization is proportional to (concentration of the chelate)Image and the monomer exponent is close to 1.5. The activation energy and the kinetic and transfer constants are evaluated. A free radical mechanism has been proposed.

Chemical modification of Methionines of Ribonuclease a with O-Benzoquinone

The accessibility of methionines in RNAase A to reaction with OBQ has been studied at highly acidic pH. The differences between the rate constants of reactions of the methionine and methionines of RNAase A with OBQ is a reflection on the limited accessibility of methionines in the protein conformation. Nevertheless, at sufficiently high OBQ concentration, all the four methionines of the enzyme can be modified. At lower concentration of OBQ, a derivative may be prepared in which a specific methionine is modified. The introduced chromophore ionizes at around pH 3 in this derivative. The derivative has partial activity towards RNA which is enhanced on addition of S-protein.

Irreversible Thermal Denaturation Of Bovine Pancreatic Ribonuclease-A

The isolation and characterization of the products formed during the irreversible thermal denaturation of enzyme RNAase-A are described. RNAase-A, when maintained in aqueous solution at pH 7.0 and 70° for 2 h, gives soluble products which have been fractionated by gel filtration on Sephadex G-75 into four components. These components are designated RNAase-At1, RNAase-At2, RNAase-At3 and RNAase-At4 according to the order of their elution from Sephadex G-75. RNAase-At4 shows the same specific activity towards yeast RNA as native RNAase-A and is virtually indistinguishable from it by the physical methods employed. However, chromatography on CM-cellulose separates it into three components that show the same u.v. spectra and specific activity towards yeast RNA as native RNAase-A. RNAase-At1, RNAase-At2and RNAase-At3 are all structurally altered derivatives of RNAase-A and they exhibit low specific activity (5–10%) towards yeast RNA. In the presence of added S-protein, all these derivatives show greatly enhanced enzymic activity. RNAase-At1 and RNAase-At2 are polymers, covalently crosslinked by intermolecular disulfide bridges; whereas RNAase-At3 is a monomer. Physical studies such as 1H-n.m.r., sedimentation analysis, u.v. absorption spectra and CD spectra reveal that RNAase-At3 is a unfolded derivative of RNAase-A. However, it is seen to possess sufficient residual structure which gives rise to a low but easily detectable enzymic activity.

Theoretical gain optimization studies in CO2-N2 lasers. III. Inclusion of line shape effects

The influence of Lorentz and Doppler line-broadening mechanisms on the small-signal optical gain of lasers and, in particular, gasdynamic lasers, is discussed. A relationship between the critical parameter reflecting the line-broadening mechanisms and some of the important parameters arising out of the gain optimization studies in CO2-N2 gasdynamic lasers is established. Using this relationship, methods by which the deleterious effect of the Doppler mechanisms on small-signal gain can be suppressed are suggested. Journal of Applied Physics is copyrighted by The American Institute of Physics.

Iron(II) and iron(III) complexes of 2,4-dithiobiuret

Ferrous and ferric complexes of 2,4-dithiobiuret (Dtb) of the type Fe(Dtb)m Xn where m, n = 1-3, and X = CI–, Br–, I– and SO 4 2– , and a neutral Fe(Dtb-H)2 complex have been synthesized and characterised by elemental analyses, magnetic susceptibility, i.r., electronic and Mössbauer spectroscopic studies. From its i.r. spectrum Dtb was found to act as a S,S-coordinating bidentate chelate. The magnetic moment, electronic and Massbauer spectra are consistent with a low spin distorted octahedral structure for the ferric complexes and a high spin form for ferrous complexes.

solation and characterization of monodeamidated derivatives of bovine pancreatic Ribonuclease A

The isolation and characterization of the initial intermediates formed during the irreversible acid denaturation of enzyme Ribonuclease A are described. The products obtained when RNase A is maintained in 0.5 M HCl at 30° for periods up to 20 h have been analyzed by ion-exchange chromatography on Amberlite XE-64. Four distinct components were found to elute earlier to RNase A; these have been designated RNase Aa2, Aa1c, Aa1b, and Aa1a in order of their elution. With the exception of RNase Aa2, the other components are nearly as active as RNase A. Polyacrylamide gel electrophoresis at near-neutral pH indicated that RNase Aa1a, Aa1b, and Aa1c are monodeamidated derivatives of RNase A; RNase Aa2 contains, in addition, a small amount of a dideamidated component. RNase Aa2, which has 75% enzymic activity as compared to RNase A, consists of dideamidated and higher deamidated derivatives of RNase A. Except for differences in the proteolytic susceptibilities at an elevated temperature or acidic pH, the monodeamidated derivatives were found to have very nearly the same enzymic activity and the compact folded structure as the native enzyme. Fingerprint analyses of the tryptic peptides of monodeamidated derivatives have shown that the deamidations are restricted to an amide cluster in the region 67–74 of the polypeptide chain. The initial acid-catalyzed deamidation occurs in and around the 65–72 disulfide loop giving rise to at least three distinct monodeamidated derivatives of RNase A without an appreciable change in the catalytic activity and conformation of the ribonuclease molecule. Significance of this specific deamidation occurring in highly acidic conditions, and the biological implications of the physiological deamidation reactions of proteins are discussed.