Pseudo four-component and regioselective synthesis of 4-amino-3,5-dicyano-6-arylphthalates using triethylamine catalyst

An efficient triethylamine-catalyzed synthesis of 4-amino-3,5-dicyano-6-arylphthalates is described.A one-pot,simple pseudo four-component reaction between arylaldehydes,dialkyl acetylenedicarboxylates, and twice as much malononitrile gave 4-amino-3,5-dicyano-6-arylphthalates in good to excellent yields.     

Real-time chirp diagnostic for ultrashort laser pulses

Using a real-time Fourier-transform algorithm, we present a simple technique for measuring the chirp of femtosecond laser pulses. We demonstrate significantly enhanced sensitivity compared with standard autocorrelation measurements.     

Tetracycline-containing Chitosan Microspheres for Local Treatment of <Emphasis Type="Italic">Helicobacter pylori</Emphasis> Infection

Helicobacter pylori infection is currently known to be the cause of at least 75% of all peptic ulcers. Although triple therapy protocols used at present in the clinics have resulted in significant benefits to the patients, the ultimate 100% eradication efficiency has never been achieved. In addition, the development of multidrug resistance to standard anti-microbial therapy can seriously hinder effective management of the disease. A rational approach to treat H. pylori, which localizes predominantly in the antral region of the stomach, is necessary for complete eradication of the infection. In this article, I review the summary of our work over the last several years on development of stomach-specific anti-H. pylori therapy using bioadhesive chitosan microspheres. To determine the gastric residence and local tetracycline concentrations as a function of time, tetracycline-containing chitosan microspheres were formulated and evaluated using the fasted Mongolian gerbil model. The H. pylori-infected gerbil model was used to evaluate the efficacy of the tetracycline-containing chitosan microsphere formulation. These preliminary results show great promise for this delivery strategy in the treatment of localized gastro-intestinal tract infections. Drug carrier systems can be engineered with the appropriate therapeutic agent(s) for efficient delivery to the target site and provide better control over localized infectious diseases. This strategy will ultimately lead to favorable clinical outcomes with less potential for resistance development.     

Polycatenar oligophenylene liquid crystals

We report the synthesis of oligophenylene polycatenar liquid crystals incorporating 1,4-disubstituted phenyl rings joined by a direct carbon carbon bond and some pyrimidine analogues. The nature of the linkages does appear to affect the mesomorphism significantly. The ratio of the aromatic core to the aliphatic chains is varied systematically by changing the number of 1,4-disubstituted phenyl rings and the length of the aliphatic chains. This strongly influences the transition temperatures of the mesophases. Some of the compounds are columnar over an extended temperature range of more than 200°C with melting points below room temperature. We suggest that a combination of the poor overlap of the conjugated electron system of the molecular cores making up the columnar structure and the high concentration of aliphatic chains leads to a low charge-carrier mobility.     

Effective electro-chemo-therapy for proliferation control of adult human mesenchymal stem cells

Clinically chemo-resistant types of cancers do not respond well to conventional therapies. To treat and enhance the efficacy of drug delivery for these cancers, we have developed an in vitro model of a combination therapy using adult human mesenchymal stem cells, electrical pulses and chemo drug. Adult Mesenchymal stem cells were used because they are similar to cancer stem cells which cause the tumor to be chemo- and radiation resistant. These cells, derived from human adult bone marrow were subjected to low voltage, long duration (200 V/cm, 40 ms and 450 V/cm, 25 ms) and high voltage, short duration (1200 V/cm, 100 μs) pulses. The effect of these voltages on the viability and proliferation ability of these cells in the presence and absence of Bleomycin (chemodrug used for treating various cancers, FDA approved in US and other respective medical agencies in other countries,) indicate the potential of transfer of this technique to clinical practice for effective electro-targeted stem cell therapy.     

Synthesis of nanoporous TiO2 materials using a doubly surfactant system and applying them as useful adsorbents

Hydrothermal and non-hydrothermal nanoporous TiO₂ materials were synthesized via a doubly surfactant route by using cationic cetyltrimethylammonium bromide and anionic sodium dodecyl sulfate surfactants as the molecular template/structure directing agent. Hydrothermal treatment was performed for comparison. The bulk chemical and phase compositions, crystalline structures, particle morphologies, thermal stabilities and surface texturing were determined by means of X-ray powder analysis, SEM and N₂ sorptiometry. The nanoporous TiO₂ materials were found to have a spherical morphology with a diameter range of 50–200 nm and a high surface area (390 m² g^?1). Hydrothermal and non-hydrothermal nanoporous TiO₂ materials were applied for adsorption of heavy metal cations and the toxic organic compound, copper phthalocyanine, from water for evaluation of their adsorption properties. Both nanoporous TiO₂ materials were found to have similar adsorption capacities toward heavy metal cations and CuPc. Both hydrothermal and non-hydrothermal TiO₂ nanoporous materials were found to have very good potential for application as a new adsorbent especially for adsorbing heavy metal cations from wastewaters.     

Polycatenar oligophenylene liquid crystals

We report the synthesis of oligophenylene polycatenar liquid crystals incorporating 1,4‐disubstituted phenyl rings joined by a direct carbon carbon bond and some pyrimidine analogues. The nature of the linkages does appear to affect the mesomorphism significantly. The ratio of the aromatic core to the aliphatic chains is varied systematically by changing the number of 1,4‐disubstituted phenyl rings and the length of the aliphatic chains. This strongly influences the transition temperatures of the mesophases. Some of the compounds are columnar over an extended temperature range of more than 200°C with melting points below room temperature. We suggest that a combination of the poor overlap of the conjugated electron system of the molecular cores making up the columnar structure and the high concentration of aliphatic chains leads to a low charge‐carrier mobility.     

Ergodicity of non-homogeneous $$\mathbf {p}$$ p -majorizing quadratic stochastic operators

Positivity - In this paper, we study the strong ergodicity of non-homogeneous $$\mathbf {p}$$ -majorizing quadratic stochastic operators acting on the finite dimension simplex. We first provide a...