Some kinetic parameters and inactivation of catalase immobilized on modified polyvinylalcohol

Polyvinylalcohol crosslinked with terephthaldicarboxaldehyde and was modified with 2-amino-4,6-dichloro-s-triazine. Optimum conditions for immobilization of catalase on modified and gelatine-coated modified polyvinylalcohol were investigated. Activity variations with respect to pH, temperature, stability behavior, andk _m(appl) values were investigated for the native and immobilized catalases. Rate constants for H₂O₂ decomposition and for inactivation of immobilized catalase were determined using a discontinuous batch-type reactor. The influence of H₂O₂ concentration on the catalase inactivation was investigated.     

New N′-alkylidene/cycloalkylidene derivatives of 5-methyl-3-phenyl-1H-indole-2-carbohydrazide: synthesis, crystal structure, and quantum mechanical calculations

The condensation products of 5-methyl-3-phenyl-1H-indole-2-carbohydrazide (1) with 2-butanone, 3-pentanone and cyclopentanone were prepared. The adducts (2a-c) were characterized by microanalysis, UV, IR, ¹H NMR, ¹³C NMR and EI mass spectrometry. ¹H NMR spectra of 2a and 2b revealed rotational restriction about the C–N bond in solution (DMSO-d₆) and displayed double resonances associated with the CH₃ and CH₂CH₃ residues of the alkylidene moieties. A variable temperature ¹H NMR experiment was run on 2a to overcome the rotational barriers and thus determine the coalescence temperature but no coalescence was observed up to 77 °C. The structural analysis of 2a and 2c were also carried out by single crystal X-ray diffraction and confirmed by theoretical calculations (semiempirical PM3 and ab initio RHF/6-31G(d)).     

Synthesis, photophysical and photochemical properties of poly(oxyethylene)-substituted zinc phthalocyanines

The synthesis, photophysical and photochemical properties of the tetra- and octa-poly(oxyethylene)substituted zinc (II) phthalocyanines are reported for the first time. The new compounds have been characterized by elemental analysis, IR, 1H and 13C NMR spectroscopy, electronic spectroscopy and mass spectra. General trends are described for photodegradation, singlet oxygen, triplet state and fluorescence quantum yields, and triplet and fluorescence lifetimes of these compounds in dimethylsulfoxide (DMSO). Photophysical and photochemical properties of phthalocyanine complexes are very useful for PDT applications. The effects of the substituents on the photophysical and photochemical parameters of the zinc(II) phthalocyanines (3a, 5a and 6a) are also reported. The singlet oxygen quantum yields (Phi(Delta)), which give an indication of the potential of the complexes as photosensitizers in applications where singlet oxygen is required (Type II mechanism) ranged from 0.60 to 0.72. Thus, these complexes show potential as Type II photosensitizers. The fluorescence of the complexes was quenched by benzoquinone (BQ).     

On the equivalence of Rolle's and generalized mean value theorems on time scales

In this note, by using elementary calculus on time scales, we recall the direct proof of the equivalence between Rolle's and generalized (Cauchy's) mean value theorems on time scales.     

The failure of reactivity indices as quantitative measures of the susceptibility of heterocyclic compounds to electrophilic substitution

The effects of poly-substitution and heteroatom substitution in benzene on the hydrogen-exchange rate are so different to the effects of the same substitutions on the nitration rate as to preclude any universal index of the susceptibility of an individual ring position towards electrophilic substitution.     

Addition of cement kiln dust in ceramic wall tile bodies

Journal of Thermal Analysis and Calorimetry - The volume of wastes generated from heavy industries, such as cement and steel industries, is increasing, and the cost of landfill disposal grows...     

Bose-Einstein condensate in a harmonic trap with an eccentric dimple potential

We investigate Bose-Einstein condensation of noninteracting gases in a harmonic trap with an offcenter dimple potential. We specifically consider the case of a tight and deep dimple potential, which is modeled by a point interaction. This point interaction is represented by a Dirac delta function. The atomic density, chemical potential, critical temperature and condensate fraction, and the role of the relative depth and the position of the dimple potential are analyzed by performing numerical calculations.     

DNA molecule manipulation by motor proteins for analysis at the single-molecule level

Massively parallel and individual DNA manipulation for analysis has been demonstrated by designing a fully self-assembled molecular system using motor proteins. DNA molecules were immobilized by trapping in a polyacrylamide gel replica, and were digested by a restriction enzyme, XhoI, for DNA analysis. One end of the λDNA was modified with biotin and the other end was modified with digoxin molecules by fragment labeling and ligation methods. The digoxin-functionalized end was immobilized on a glass surface coated with anti-digoxigenin antibody. The biotinylated end was freely suspended and experienced Brownian motion in a buffer solution. The free end was attached to a biotinylated microtubule via avidin–biotin biding and the DNA was stretched by a kinesin-based gliding assay. A stretched DNA molecule was fixed between the gel and coverslip to observe the cleavage of the DNA by the enzyme, which was supplied through the gel network structure. This simple process flow from DNA manipulation to analysis offers a new method of performing molecular surgery at the single-molecule scale. Figure DNA molecule manipulation by motor proteins for analysis at the single-molecule level     

Anticholinesterase activity screening of some novel dithiocarbamate derivatives including piperidine and piperazine moieties

The present study was undertaken to synthesize some novel lipophilic piperazine and piperidinedithiocarbamates and investigate their inhibitory potencies against cholinesterase enzymes. In the synthetic studies, 44 new compounds were isolated. The structures of the synthesized compounds were confirmed by spectroscopic analyses. Enzymatic studies were carried out using modified Ellman's assay against Acetylcholinesterase (AChE) and Butrylcholinesterase (BChE) enzymes, and it was observed that some of the compounds selectively inhibit AChE. Theoretical ADME predictions were calculated for selected compounds in the series. Enzyme kinetics and molecular docking studies were performed for the most active compound C41 and nature of inhibition and interactions between enzyme and ligand were explained.