Synthesis, spectral characterization, biological and fluorescence studies of lanthanum(III) complexes with 3-substituted-4-amino-5-hydrazino-1,2,4-triazole Schiff bases

Some lanthanum(III) complexes have been synthesized by reacting lanthanum(III) nitrate with Schiff bases derived from 3-substituted-4-amino-5-hydrazino-1,2,4-triazole and substituted salicylaldehydes. All these complexes are soluble in DMF and DMSO and the low molar conductance values observed indicates that they are non-electrolytes. Elemental analyses suggest the complexes have 1:1 stoichiometry of the type La · L · NO₃ · H₂O, and they were characterized further by spectral and thermogravimetric methods. Fluorescence spectra of one of the representative Schiff bases (II) and its lanthanum(III) complex were investigated in various solvents; the complexes were evaluated for their biological activity.     

Synthesis and antibacterial activity of azodispersed dyes incorporating a phthalazinedione moiety for dyeing polyester fabrics

Abstract  

3-(1,4-Dioxo-3,4,4a,5,10,10a-hexahydro-1H-5,10-benzenobenzo[g]phthalazin-2-yl)-3-oxopropionitrile and 3-(1,4-dioxo-3,4,4a,5,10,10a-hexahydro-1H-5,10-benzenobenzo[g]phthalazin-2-yl)-3-oxo-2-(5-oxo-3-phenylthiazolidin-2-ylidene)propionitrile were coupled with various diazotized aryl amines in pyridine to give the corresponding aryl hydrazonopropionitriles. Some of the dyes produced were applied to polyester as disperse dyes, and their antibacterial, color, and fastness properties were evaluated.     

Homotopy invariance of perturbations of D ∞-differential modules

The notion of a perturbation of a D _∞-differential module is introduced. It is shown that the perturbations of a D _∞-differential module are homotopy invariant.     

Deadlock Detection for a Class of Communicating Finite State Machines

LetMandNbe two communicating finite state machines which exchange one type of message. We develope a polynomial algorithm to detect whether or notMandNcan reach a deadlock. The time complexity of the algorithm isO(m^{3}n^{3}and its space isO(mn)wheremandnare the numbers of states inMandN, respectively. The algorithm can also be used to verify that two communicating machines which exchange many types of messages are deadlock-free.     

A periodic state exchange protocol and its verification

We present an elegant protocol for reliably transmitting data messages from a sender to a receiver over a highspeed network that may reorder, lose, or corrupt messages. The protocol is based on a new principle that calls for the periodic exchange of state information between the sender and receiver. Our formal definition of the protocol is abstract and does not include explicit timing information such as the rate of sending state information. The abstract definition makes our formal verification of the protocol simple and based solely on well-established concepts: invariants, well-foundedness, and action fairness. We use the formal definition of the protocol and its proof of correctness to deduce the required timing information. In particular, we show that the rate of sending state information is at most (m-1)/2T where m is a measure of the memory size in the sender, and T is an upper bound on the required time for one message to be sent, propagated, and received between the sender and receiver     

Molecular dynamics simulation study of the negative correlation in antibody AZ28-catalyzed oxy-cope rearrangement

The oxy-Cope rearrangement reaction in the antibody AZ28 is investigated using ab initio molecular orbital calculations and molecular mechanical molecular dynamics simulations. This antibody, AZ28, is known as one of the few systems where the mature catalytic antibody shows a negative correlation between the transition state analogue (TSA) binding affinity and the catalytic rate of the oxy-Cope rearrangement compared to the germ line catalytic antibody. The ab initio optimized structure shows that the transition state structure has a more planar configuration than the TSA. The favorable electrostatic interactions between AZ28 and the transition state analogue overcome the unfavorable van der Waals interactions; thus, AZ28 shows higher binding affinity for the TSA than the germ line. However, the AZ28 is not flexible enough to accept the relatively planar transition state structure. Because the lower flexibility causes poorer antibody-hapten interaction energies, the activation free energy of the oxy-Cope rearrangement becomes larger in the mature antibody than the germ line. We show that the differences in flexibility between the germ line and the mature form and the differences in structure between TSA and the transition state are the origin of the negative correlation in AZ28-catalyzed oxy-Cope rearrangement. The mutation of residue 34 of the light chain, 34(L), affects the binding free energies through the interresidue interaction because it is the closest to the hapten among the six mutatable residues. However, it does not affect the negative correlation.     

Benzaldehyde, 2-hydroxybenzoyl hydrazone derivatives as inhibitors of the corrosion of aluminium in hydrochloric acid

The effect of benzaldehyde, 2-hydroxybenzoyl hydrazone derivatives on the corrosion of aluminium in hydrochloric acid has been investigated using thermometric and polarization techniques. The inhibitive efficiency ranking of these compounds from both techniques was found to be: 2>3>1>4. The inhibitors acted as mixed-type inhibitors but the cathode is more polarized. The relative inhibitive efficiency of these compounds has been explained on the basis of structure of the inhibitors and their mode of interaction at the surface. Results show that these additives are adsorbed on an aluminium surface according to the Langmuir isotherm. Polarization measurements indicated that the rate of corrosion of aluminium rapidly increases with temperature over the range 30-55 degrees C both in the absence and in the presence of inhibitors. Some thermodynamic data of the adsorption process are calculated and discussed.     

Reversible denaturation behavior of immobilized glucose oxidase

Glucose oxidase (GOD) was immobilized by using glutaraldehyde crosslinking and various stabilizing agents such as BSA, gelatin, lysozyme, and polyethylenimine (PEI). Studies on the denaturation of the soluble as well as immobilized GOD were carried out for 1 h at various concentrations of guanidine hydrochloride (GdmCl) in 50 mM phosphate buffer, pH 6.0 at 25±1°C. The soluble enzyme required a GdmCl concentration of 5M for total activity loss, whereas for GOD immobilized with BSA, gelatin, lysozyme, and heat-inactivated lysozyme, the corresponding GdmCl concentration required was 8 M. GOD immobilized with PEI, however, was more stable and retained 25% activity when denatured for 1 h using 8 M GdmCl. However, after undergoing denaturation for 1 h, GOD immobilized with lysozyme regained 72% original activity within 20 min of renaturation, while GOD immobilized with BSA, PEI, gelatin, and heat-inactivated lysozyme regained only 39, 21, 20, and 25% of activity, respectively. After five cycles of repeated denaturation and renaturation with 8 M GdmCl, GOD immobilized with lysozyme retained 70% of the original activity. Refolding ability of lysozyme, glutaraldehyde crosslinkages between lysozyme and GOD, together with ionic interactions between them, appear to play an important role in the denaturation-renaturation behavior of the immobilized enzyme.     

Utility of oxidation-reduction reaction for the determination of ranitidine hydrochloride in pure form,in dosage forms and in the presence of its oxidative degradates

Three simple, accurate and sensitive colorimetric methods (A, B and C) for the determination of ranitidine HCl (RHCl) in bulk sample, in dosage forms and in the presence of its oxidative degradates are described. The first method A is based on the oxidation of the drug by N-bromosuccinimide (NBS) and determination of the unreacted NBS by measurement of the decrease in absorbance of amaranth dye (AM) at a suitable lambda(max)=520 nm. The methods B and C involve the addition of excess Ce(4+) and determination of the unreacted oxidant by decrease the red color of chromotrope 2R (C2R) at a suitable lambda(max)=528 nm for method B or decrease the orange pink color of rhodamine 6G (Rh6G) at a suitable lambda(max)=526 nm for method C. Regression analysis of Beer-Lambert plots showed good correlation in the concentration ranges 0.2-3.6, 0.1-2.8 and 0.1-2.6 microg ml(-1) for methods A, B and C, respectively. The apparent molar absorptivity. Sandell sensitivity, detection and quantitation limits were calculated. For more accurate results, Ringbom optimum concentration ranges were 0.3-3.4, 0.2-2.6 and 0.2-2.4 microg ml(-1) for methods A, B and C, respectively. Analyzing pure and dosage forms containing RHCl tested the validity of the proposed methods. The relative standard deviations were 相似文献