[en] In an attempt to develop potent antitumor agents, new 1,3,4-thiadiazole derivatives were synthesized and evaluated for their cytotoxic effects on multiple human cancer cell lines, including the K562 chronic myelogenous leukemia cell line that expresses the Bcr-Abl tyrosine kinase. N-(5-Nitrothiazol-2-yl)-2-((5-((4-(trifluoromethyl)phenyl)amino)-1,3,4-thiadiazol-2-yl)thio)acetamide (2) inhibited the Abl protein kinase with an IC₅₀ value of 7.4 µM and showed selective activity against the Bcr-Abl positive K562 cell line. Furthermore, a Bcr-Abl-compound 2 molecular modelling simulation highlighted the anchoring role of the nitrothiazole moiety in bonding and hydrophobic interaction with the key amino acid residues. These results provide promising starting points for further development of novel kinase inhibitors.

[en] 1-hydroxybenzotriazole derivatives are used with carbodiimide as additives to generate active esters during peptide bond formation. They are also used as additives during the peptide bond formation. Dissociation constants of the 1-hydroxybenzotriazole (HOBt) and its derivatives, 1-hydroxy-6-chloro benzotriazole, 1-hydroxy-6-trifluoro methylbenzotriazole, 1-hydroxy-6-nitrobenzo-triazole were determined spectrophotometrically in 95% acetonitrile-water. In addition, 7-aza-1-hydroxybenzotriazole (7-HOAt) and 4-aza-1-hydroxybenzotriazole (4-HOAt) were also studied. Recently, oxyma was reported as a good replacement for the benzotriazole derivatives. As alcoholic components of active esters, the oximes seem to be good leaving groups. Therefore it was expected, that the strongly acidic and nucleophilic oximes, which possess electron-withdrawing groups in the molecule, are suitable as additives during the peptide bond formation. The dissociation constant of some oximes, such as diethyl 2-(hydroxyimino)malonate, ethyl 2-cyano-2-(hydroxyimino)acetate (oxyma), hydroxycarbonimidoyl dicyanide and N-hydroxypicolinimidoyl cyanide in 95% acetonitrile-water are reported. (author)

[en] Bromocarbazoles and chlorocarbazoles are emerging environmental contaminants that have been reported to be persistent and possessing dioxin-like toxicity; however, their photodegradative fate in water is unknown. The photodegradation of 3-bromocarbazole, 3-chlorocarbazole, and 3,6-dichlorocarbazole was determined in ultrapure water. They proceeded by direct photolysis and followed first-order kinetics. The rate constants (k) were 0.4838, 0.3454, and 0.4422 h⁻¹ corresponding to half-lives (t_1/2) 1.81, 2.01, and 1.62, while the quantum yields (Ф) were 0.232, 0.180, and 0.295 respectively. The maximum wavelengths of absorption (λ_max) were in the near ultraviolet region (295, 296, 299, and 301 nm) implying these compounds are likely to degrade slowly under sunlight in natural aquatic environment. The molar extinction coefficients (ε) determined in acetonitrile were 18,573, 17,028, 13,385, and 14,010 L mol⁻¹ cm⁻¹, respectively, the latter being 3,6-dibromocarbazole. A bathochromic shift was observed with halogen addition on their respective mono-substituted congeners. Bromocarbazoles were observed to degrade faster in water than chlorocarbazoles. In addition, photodegradation was estimated to proceed faster in summer than in winter, in natural water system at 50° N latitude. In the absence of light, hydrolytic degradation occurred but proceeded very slowly. Hexahydroxybenzene and trihydroxycarbazole were positively identified as the likely photoproducts with the former being a known toxic compound. Dehalogenation, oxidative cleavage, hydroxylation, and hydrolysis are suggested as the major photodegradation mechanisms in water, yielding phototoxic products that may be of enhanced toxicity than the parent compounds.

[en] The results of studies in the field of rigid-rod poly(benzobisazoles) and molecular composites based on them are analysed and generalised. Poly(benzobisazoles) are most promising candidates for high-strength and high-modulus polymeric materials, while the molecular composites based on them can be employed in the synthesis of polymeric materials with a broad spectrum of mechanical properties. The bibliography includes 101 references.

[en] Objective: To assess the correlation between biofilm formation and azole antifungal susceptibility against plank tonic and sessile clinical isolates of C.albicans. Study Design: Prospective observational study. Place and Duration of Study: Combined Military Hospital Peshawar, from Jun 2016 to Sep 2017. Methodology: All standard microbiological procedures were carried out according to latest Clinical & laboratory standard institute (CLSI) guidelines. After gram staining and presumptive identification on CHRO Magar Candida, the isolates were biochemically identified by API AUX Candida as C.albicans. Planktonic antifungal susceptibility was carried out by Kirby Bauer disk diffusion method on 300 C.albicans isolates. Broth microdilution method was used to determine Minimum inhibitory concentration (MICs) of plank tonic cells and micro titer assay was used for assessment of biofilm formation by C.albicans. Results: In planktonic antifungal susceptibility, fluconazole was susceptible against 195 (65%) and voriconazole against 241 (80%) C. albicans isolates. C. albicans was found susceptible dose dependent (SDD) to fluconazole in 28 (9%) and to voriconazole in 21 (7%) isolates. Seventy-seven (26%) and 38 (13%) C.albicans isolates were found fluconazole and voriconazole resistant, respectively. Sessile antifungal susceptibility was carried out through broth micro dilution method in which 160 (53%) were susceptible, 42 (14%) were susceptible dose dependent SDD and 98 (33%) were resistance to voriconazole, and 161 (54%) were susceptible, 36 (12%) were SDD and 103 (34%) were found resistant to fluconazole. Biofilm forming isolates of C.albicans were observed to be 285 (95%).The p-value is highly significance i.e. <0.01 between the biofilm formation and azole antifungal susceptibility against plank tonic and sessile clinical isolates of C.albicans. Conclusion: Plank tonic C.albicans clinical isolates appeared more susceptible to voriconazole than fluconazole and sessile isolates. Biofilm formation was very high among all the isolates of C.albicans. (author)

[en] The synthesis is described of ¹⁴C labelled forms of 2-(3-methoxyphenyl)-5,6-dihydro-s-triazolo[5,1-a]isoquinoline and 2-(3-ethoxyphenyl)-5,6-dihydro-s-triazolo[5,1-a]isoquinoline. (author)

[en] Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and equipment. Unfortunately, there is a lack of analysis of radionuclides with coupled electrochemical techniques and microliter volume reactors. The goals of this work are (1) to develop a miniaturized micro-electrochemical quartz crystal microbalance (μeQCM) reactor for use in small volume (50-200 μL) electrogravimetric experiments and (2) to use this reactor to characterize the preconcentration of neptunium on carbon electrodes via electroprecipitation. We successfully deposited neptunium in the new μeQCM reactor and verified its operation. We found that preconcentration of neptunium on carbon coated electrodes was possible by chronoamperometry at - 1.6 V_Ag/AgCl. The mass shift of the resulting precipitate was indicative of the amount of neptunium on the electrode, although the correlation between the mass increase and activity of the preconcentrated material was not linear. Neptunium precipitate reduced electron transfer to the solution as evidenced by the increase in charge transfer resistance compared to bare electrodes. (author)

No abstract available

[en] A series of styryl-carbazole derivatives (with and without a silicon atom) were investigated in n-hexane and in acetonitrile in terms of their spectroscopic and photophysical properties. The major question addressed in this work is how the presence of a trimethylsilyl group modifies the absorption and emission properties of styryl-carbazoles depending whether vinyl groups are in a meta- or para- position. It was observed that only para-styryl-carbazole containing silicon undergoes a solvent-induced inversion of its lowest singlet excited states whereas meta-styryl-carbazole containing silicon retains the properties of the meta-styryl-carbazole itself. The different character of the emissive state was deduced from its 7-fold larger radiative rate constant in acetonitrile compared to results in n-hexane. DFT calculations revealed on the molecular level why inversion of the excited states occurs only for this silicon-based styryl-carbazole whose vinyl group is in the para- and not in the meta- position.

[en] The pore-filled membranes with scintillating properties have been synthesized by in-situ UV grafting of monomer Bis (2- (methacryloxy)ethyl) phosphate in pores of the microporous host membranes. The polymerization has been carried in presence of scintillating molecules, 2,5-diphenyloxazole, which are physically trapped in the polymer matrix. The membranes have been prepared with two host materials, poly (propylene) and poly (ethersulfone). Much higher scintillation efficiency has been obtained for PES based grafted membranes owing to its aromatic backbone. The scintillation response of PES based membranes have been found to be linear over the range of ²⁴¹Am activity studied. The membranes have been found to be stable and reusable. (author)