Synthesis and characterization of N-substituted 1,4,5,6-tetrahydropyrimidine containing functional polymers as SO2 and CO2 sorbents

Novel vinyl monomers containing 1,4,5,6-tetrahydropyrimidine were prepared by the reaction of N-substituted-1,3-diaminopropane with N,N-dimethyl-formamide dimethylacetal, which gave 1-alkyl or aryl substituted 1,4,5,6-tetrahydropyrimidines, Alkylation of the tetrahydropyrimidine derivatives by chloromethylstyrene produces the N-methyl-N′-vinyl benzyl-1,4,5,6-tetrahydropyrimidinium chloride in high yields. These monomers were readily polymerized in dimethylformamide by AIBN at 80°C. Homopolymers and soluble linear copolymers were prepared and copolymerization parameters were rationalized. Further, insoluble terpolymers prepared from these monomers, styrene and divinylbenzene were tested for the sorption of the weakly acidic gases gave excellent results. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2411–2420, 1997     

1,1′,3,3′‐Tetraalkyl‐2,2′‐biperimidinylidenes: Unexpected substituent effects on the reactivity of carbon–carbon double bond

C₂ deprotonation of 1,3‐dibutylperimidinium bromide ( 1a ) with sodium hydride and a catalytic amount of potassium tert‐butoxide in dry THF led to the formation of the exceptionally inert tetraaminoalkene 2a . In contrast, isostructural tetrakis(2‐methoxyethyl)‐tetraaminoalkene ( 2b ) instantaneously reacted with O₂ to yield urea 3b , and silver nitrate was readily reduced with 2b to form a silver mirror. Compound 2a has been characterized by X‐ray diffraction studies; the naphtho‐pyrimidine skeleton imposes structural constraints and some rigidity to the CC bonding. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:82–87, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10088     

Characterization of Poly(vinyl alcohol)/Chitosan Hydrogels as Vascular Tissue Engineering Scaffolds

In this study, PVA/Chitosan hydrogels were fabricated by freeze/thaw cycles and further crosslinking with a KOH/Na₂SO₄ coagulation bath and the effect of freeze/thaw cycle number on cell behaviour was evaluated. The surface of the hydrogels were further modified with Collagen type I adsorption and seeded with bovine aortic vascular smooth muscle and endothelial cells. Increasing the number of freeze/thaw cycles resulted in a marked change in surface morphology, hydrophilicity and protein adsorption. Collagen coating caused an increase in initial attachment and proliferation. We concluded that hydrogels that have undergone 3 freeze/thaw cycles were optimum for cell attachment both in the presence and the absence of coating.     

Thin-layer drying of tomato (<Emphasis Type="Italic">Lycopersicum esculentum Mill. cv. Rio Grande</Emphasis>) slices in a convective hot air dryer

The effects of different drying temperatures on the drying kinetics of tomato slices were investigated using a cabinet-type dryer. The experimental drying data were fitted best to the to the Page and Modified Page models apart from other theoretical models to predict the drying kinetics. The effective moisture diffusivities varied from 1.015 × 10⁻⁹ to 2.650 × 10⁻⁹ m² s⁻¹over the temperature range studied, and activation energy was 22.981 kJ mol⁻¹.     

Cytotoxic Tolerance of Healthy and Cancerous Bone Cells to Anti-microbial Phenolic Compounds Depend on Culture Conditions

Applied Biochemistry and Biotechnology - Carnosol and carnosic acid are polyphenolic compounds found in rosemary and sage with known anti-oxidant, anti-inflammatory, and anti-microbial properties....     

Near‐IR Absorbing BODIPY Derivatives as Glutathione‐Activated Photosensitizers for Selective Photodynamic Action

Enhanced spatiotemporal selectivity in photonic sensitization of dissolved molecular oxygen is an important target for improving the potential and the practical applications of photodynamic therapy. Considering the high intracellular glutathione concentrations within cancer cells, a series of BODIPY‐based sensitizers that can generate cytotoxic singlet oxygen only after glutathione‐mediated cleavage of the electron‐sink module were designed and synthesized. Cell culture studies not only validate our design, but also suggest an additional role for the relatively hydrophobic quencher module in the internalization of the photosensitizer.