Preparation of l-Lactide/3-Glycidyloxypropyltrimethoxysilane Copolymeric Materials with Various Catalysts

Copolymerization reactions of 3-glycidyloxypropyltrimethoxysilane (GPTS) with l-lactide (LLA) at 100 °C for different time intervals are performed by various catalysts such as zirconium perfluoroheptanoate, and commercially available Tin(II) chloride (SnCl₂) and sodium trimethylsilanolate (NaOSiMe₃). Homo- and copolymers are characterized by FTIR, ¹H- and ¹³C-NMR spectroscopies, electrospray ionization mass spectroscopy, thermal gravimetric analysis, differential scanning calorimetry and gel permeation chromatography. All selected catalysts are effective in ROP of monomers. Especially, SnCl₂ is more reactive catalyst in the copolymerization of LLA/GPTS. The structure of final product is found as random copolymers.     

The adherence of <Emphasis Type="Italic">Candida albicans</Emphasis> to acrylic resin reinforced with different fibers

One important aethiological factor in the pathogenesis of chronic atrophic candidosis is the presence of Candida albicans on the fitting surface of the dentures. Fibers may come into contact with oral mucosa during the finishing procedures of acrylic resins. The exposed fibers may provide mechanical retention for yeast cells at the interface of the components. The effect of two different glass fibers and two different environments were evaluated in respect of Candida albicans adhesion to the acrylic surface. Half of the acrylic samples reinforced with two different fibers (Sticknet and Eversticknet) were pretreated with phosphate-buffered saline (PBS) and the rest with unstimulated saliva. The test specimens were placed in yeast suspension. The adhered cells were examined with a scanning electron microscope. The amount of adhered cells in PBS was lower for Eversticknet but the difference was not significant (p > 0.05). The number of yeast cells decreased in saliva for both groups and the difference was statistically significant for the samples reinforced with Eversticknet (p < 0.01). The use of Sticknet or Eversticknet as reinforcing material for poly(methylmethacrylate) had no effect on surface topography due to the same adhesion state of Candida albicans. The presence of a salivary pellicle derived from unstimulated saliva reduced adhesion of Candida albicans.     

Effects of modified atmosphere and vacuum packaging on microbiological and chemical properties of rainbow trout (Oncorynchus mykiss) fillets

Microbial (psychrotrophic, mesophilic aerobic bacteria and Enterobacteriacae counts), and chemical analysis [pH, total volatile bases nitrogen (TVB-N), lipid oxidation (Thiobarbituric acid reactive substance, TBARS)] of rainbow trout (Oncorynchus mykiss) fillets in air (control), vacuum and modified atmosphere packaging (MAP) with various gas mixtures conditions at 4+/-1 degrees C were determined. The gas mixtures evaluated were 100% CO2, 2.5% O2+7.5% N2+90% CO2 and 30% O2+30% N2+40% CO2. Psychrotrophic bacteria count was above 1 x 10(7) cfu/g on the 12th day in 100% CO2. However; mesophilic bacteria count was below 1 x 10(6) cfu/g at the end of the 14-day storage period. Enterobacteriaceae count was significantly lower in samples packaged with MAP. Lipid oxidation increased rapidly after 6 days of storage in the samples containing 30% O2. While minimum TBARS values were recorded in fillets containing 100% CO2 and vacuumed fillets, the lowest TVB-N values were obtained in fillets with 100% CO2.     

Cellular genetic algorithm technique for the multicriterion design optimization

There have been increased activities in the study of genetic algorithms (GA) for problems of design optimization. The present paper describes a fine-grained model of parallel GA implementation that derives from a cellular-automata-like computation. The central idea behind the Cellular Genetic Algorithm approach is to treat the GA population as being distributed over a 2-D grid of cells, with each member of the population occupying a particular cell and defining the state of that cell. Evolution of the cell state is tantamount to updating the design information contained in a cell site, and as in cellular automata computations, takes place on the basis of local interaction with neighboring cells. A focus of the paper is in the adaptation of the cellular genetic algorithm approach in the solution of multicriteria design optimization problems. The proposed paper describes the implementation of this approach and examines its efficiency in the context of representative design optimization problems.     

A review on microalgal growth stress parameters for sustainable biofuel production

Clean Technologies and Environmental Policy - Rapid growth and high carbon-fixation properties make microalgal biomass a preferred source of energy-production technologies, particularly biodiesel...     

Broad-Wavelength Light-Driven High-Speed Hybrid Crystal Actuators Actuated Inside Tissue-Like Phantoms

Research on molecular crystals exhibiting light-driven actuation has made remarkable progress through the development of various molecules and the identification of driving mechanisms. However, crystals developed to date have been driven mainly by ultraviolet (UV) or blue light irradiation, and driving by red or near-infrared (NIR) light has not been attempted yet. Herein, a broad-wavelength light-driven molecular crystals that exhibit high-speed bending by photothermal effect is developed. Titanium carbide (Ti₃C₂T_x) MXene nanosheets are integrated into salicylideneaniline crystals to extend the wavelength range that causes photothermally driven bending to UV, visible, and NIR light. In addition, unlike the thin pristine molecular crystals that show slow photoisomerization-induced bending only under UV light, the MXene layer enables the molecular crystals to be actuated rapidly regardless of their thickness over a wide range of wavelengths. The hybridization of molecular crystals with MXene, which exhibits strong biocompatibility as well as NIR light-driven photothermal effect, allows for the bending of the hybrid crystals inside agar phantoms mimicking biological tissue. Last, it is confirmed that MXene hybridization can be extended to common molecular crystals including various salicylideneaniline and anisole derivatives.