Responsive microgrooves for the formation of harvestable tissue constructs

Given its biocompatibility, elasticity, and gas permeability, poly(dimethylsiloxane) (PDMS) is widely used to fabricate microgrooves and microfluidic devices for three-dimensional (3D) cell culture studies. However, conformal coating of complex PDMS devices prepared by standard microfabrication techniques with desired chemical functionality is challenging. This study describes the conformal coating of PDMS microgrooves with poly(N-isopropylacrylamide) (PNIPAAm) by using initiated chemical vapor deposition (iCVD). These microgrooves guided the formation of tissue constructs from NIH-3T3 fibroblasts that could be retrieved by the temperature-dependent swelling property and hydrophilicity change of the PNIPAAm. The thickness of swollen PNIPAAm films at 24 °C was approximately 3 times greater than at 37 °C. Furthermore, PNIPAAm-coated microgroove surfaces exhibit increased hydrophilicity at 24 °C (contact angle θ = 30° ± 2) compared to 37 °C (θ = 50° ± 1). Thus PNIPAAm film on the microgrooves exhibits responsive swelling with higher hydrophilicity at room temperature, which could be used to retrieve tissue constructs. The resulting tissue constructs were the same size as the grooves and could be used as modules in tissue fabrication. Given its ability to form and retrieve cell aggregates and its integration with standard microfabrication, PNIPAAm-coated PDMS templates may become useful for 3D cell culture applications in tissue engineering and drug discovery.     

η3‐Diphosphavinylcarbene: A P2 Analogue of the Dötz Intermediate

Do the twist : The reaction of in situ generated phosphinidenes with phosphaalkynes is a facile route to the new metal‐coordinated η³‐diphosphavinylcarbene 1 , which shows facile ligand‐exchange reactions and undergoes an unprecedented rearrangement that involves phosphinidene complex 2 and η³‐phosphaalkenylphosphinidene complex 3 , the 1,3 isomer of 1 .

     

The effect of topical ethanol extract of Cotinus coggygria Scop. on cutaneous wound healing in rats

The aim of this study is to determine the cutaneous wound healing effects of the ethanol extract of Cotinus coggygria leaves in rats by excision wound model to provide scientific evidence for the traditional use of C. coggygria Scop. The levels of malondialdehyde, catalase, superoxide dismutase, glutathione and hydroxyproline were investigated in wound tissues. Histopathological examination was also performed. The hydroxyproline content of the granulation tissue and the glutathione levels were both significantly higher in the treatment group than in the control group (p < 0.05 for both); while the malondialdehyde levels were significantly lower in the treatment group (p < 0.05). These results were supported with histological results. The ethanol extract of C. coggygria Scop could be considered as an effective agent in wound healing in accordance with its traditional use.     

Chiral lariat ethers as membrane carriers for chiral amino acids and their sodium and potassium salts

Four chiral lariat ethers 8–11 containing a (p-methoxyphenoxy) methyl side arm were used for chiral discrimination of amino acids in their zwitterionic form or as potassium and sodium salts in transport across a bulk chloroform membrane with satisfactory selectivity. The carriers that were employed exhibited different transport selectivity relative to the amino acids and their salts under study. The d/l selectivity strongly depends on the amino acids or their salts, and in some cases reverse selectivity has been obtained. The best selectivity was obtained in the case of tyrosine and its potassium salts for all carriers. The transport rates of amino acids and their salts were found to be controlled by factors such as the structure of the carriers and amino acids or their salts. Among these factors, it was also found that the side arm of the lariat ethers plays an important role in the transport process. As a consequence, the main goal of our investigation was to separate the chiral amino acids through liquid membranes.     

Theoretical investigation of triazine based a star shape pyrrole monomer

In this work, we report a comprehensive theoretical investigation of electroactive star shaped pyrrole functionalized triazine monomer with two main goals. First goal of this work is to explore the physical and chemical properties of the monomer, then to investigate correlation between the experimental and the theoretical properties of monomer. The scale factor which is calculated from B3LYP/cc-pVDZ was determined as 0.985 for FT-IR and it is an important and reliable contribution to the literature. It is determined that the most appropriate basis set for this molecule. The other novel objective of this research is to investigate temperature effect on displacement of chlorine atoms in 2,4,6-trichloro-1,3,5-triazine. This method applied for the first time in the literature for triazines is especially crucial to the synthesis of unsymmetrical triazines.     

Thermal and kinetic analysis of uranium salts

The thermal decomposition kinetics of UO₂C₂O₄·3H₂O were studied by TG method in a flowing nitrogen, air, and oxygen atmospheres. It is found that UO₂C₂O₄·3H₂O decomposes to uranium oxides in four stages in all atmosphere. The first two stages are the same in the whole atmosphere that correspond to dehydration reactions. The last two stages correspond to decomposition reactions. Final decomposition products are determined with X-Ray powder diffraction method. Decomposition mechanisms are different in nitrogen atmosphere from air and oxygen atmosphere. The activation energies of all reactions were calculated by model-free (KAS and FWO) methods. For investigation of reaction models, 13 kinetic model equations were tested and correct models, giving the highest linear regression, lowest standard deviation, and agreement of activation energy value to those obtained from KAS and FWO equations were found. The optimized value of activation energy and Arrhenius factor were calculated with the best model equation. Using these values, thermodynamic functions (??H ^*, ??S ^*, and ??G ^*) were calculated.     

Synthesis of Novel Chiral C 2-symmetric Diaza-18-crown-6 Ether Derivatives and their Enantioselective Recognition of Amino Acid Derivatives

New chiral diaza-18-crown-6 ether derivatives, 5 and 6 were synthesized from (R)-(-)-2-amino-1-bütanol. These chiral artificial receptors exhibit pronounced chiral recognition toward the enantiomers of l- and d- amino acid derivatives. The highest enantioselectivity was observed in the case of Trp-OMe·HCl (K_D/K_L=12.5).     

Dynamics of Ginzburg‐Landau Vortices

(Accepted August 19, 1996)