Improvement of the mechanical and barrier properties of methylcellulose-based films by treatment with HEMA and silane monomers under gamma radiation

Methylcellulose (MC)-based films were prepared by casting from its 1% aqueous solution containing 0.5% vegetable oil, 0.25% glycerol and 0.025% Tween^®-80. Puncture strength (PS), puncture deformation (PD) and water vapor permeability (WVP) of the films were found to be 147 N/mm, 3.46 mm, and 6.34 g mm/m² day kPa, respectively. The monomer, 2-hydroxyethyl methacrylate (HEMA) (0.1–1%, w/w) was incorporated into the MC-based solution and films were prepared by casting. Films were then exposed to gamma radiation (5–25 kGy) and it revealed that 1% HEMA containing films showed the highest PS values (282 N/mm at 10 kGy). Silane monomer (3-aminopropyl tri-ethoxy silane) (0.1–1%, w/w) was also added into the MC-based films and were found to improve the strength of the films significantly. In comparison between HEMA and silane treatment onto MC-based films, it was observed that silane performed better strength and barrier properties. Surface morphology of the monomer treated films was examined by scanning electron microscopy and suggested better appearance than MC-based film.     

Synthesis of (S)-(+)-cericlamine through lipase-catalyzed aminolysis of azo acetates

The kinetic enzymatic resolution of azo acetates via aminolysis with Candida antarctica lipase B has been investigated using benzylamine as amine component. The products obtained from this biotransformation in high enantiomeric purity can serve as valuable precursors for various amino alcohols, as exemplified by the synthesis of the serotonin reuptake inhibitor (S)-(+)-cericlamine.     

RNA and DNA association to zwitterionic and charged monolayers at the air-liquid interface

The objective of this work is to establish under which conditions short RNA molecules (similar to miRNA) associate with zwitterionic phospholipids and how this differs from the association with cationic surfactants. We study how the base pairing (i.e., single stranded versus double stranded nucleic acids) and the length of the nucleic acid and the charge of the lipid/surfactant monolayer affect the association behavior. For this purpose, we study the adsorption of nucleic acids to monolayers composed of dipalmitoyl phosphatidylcholine (DPPC) or dioctadecyl-dimethyl-ammoniumbromide (DODAB) using the surface film balance, neutron reflectometry, and fluorescence microscopy. The monolayer studies with the surface film balance suggested that short single-stranded ssRNA associates with liquid expanded zwitterionic phospholipid monolayers, whereas less or no association is detected for double-stranded dsRNA and dsDNA. In order to quantify the interaction and to determine the location of the nucleic acid in the lipid/surfactant monolayer we performed neutron reflectometry measurements. It was shown that ssRNA adsorbs to and penetrates the liquid expanded monolayers, whereas there is no penetration of nucleic acids into the liquid condensed monolayer. No adsorption was detected for dsDNA to zwitterionic monolayers. On the basis of these results, we propose that the association is driven by the hydrophobic interactions between the exposed hydrophobic bases of the ssRNA and the hydrocarbon chains of the phospholipids. The addition of ssRNA also influences domain formation in the DPPC monolayer, leading to fractal-like interconnected domains. The experimental results are discussed in terms of the implication for biological processes and new leads for applications in medicine and biotechnology.     

Binding of 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane with tetra(methyl viologen) calix[4]resorcinol

Binding of an amphiphilic dianion 1,5-bis(p-sulfonatophenyl)-3,7-diphenyl-1,5-diaza-3,7-diphosphacyclooctane (APCO^2?) with an amphiphilic octacation tetra(methyl viologen) calix[4]resorcinol (MVCA⁸⁺) in media containing different amounts of water and DMSO using NaClO₄ or NaCl as supporting electrolytes was shown for the first time by cyclic voltammetry and spectrophotometry. The stoichiometry of the complex depends on the MVCA⁸⁺: APCO^2? ratio, medium, and supporting electrolyte. A 1: 1 charge-transfer complex is mainly formed (λ_max = 480 nm) in 30% DMSO at a ratio of the compounds of 1: 1. A similar 1: 1 complex of APCO^2? with a model compound methyl viologen MV²⁺ (λ_max = 482 nm) is formed under these conditions. A donor-acceptor interaction occurs between the acceptor viologen units and nitrogen-centered electron-donating fragments of the APCO^2? dianion. An increase in the content of APCO^2? in the solution leads to an additional binding of one (30 vol.% DMSO, water, NaClO₄) or two (30 vol.% DMSO, water, NaCl) particles of APCO^2? with the hydrophobic fragments of MVCA⁸⁺. The complexes aggregate to form insoluble precipitates in aqueous and water-DMSO media. A selective reversible electroswitching from the bound to free state of one of the three bound APCO^2? particles was performed when reducing MVCA⁸⁺ to MVCA^4·+ in a 30 vol.% DMSO/NaCl medium.     

Single breath-hold multi-slab and cine cardiac-synchronized gadolinium-enhanced three-dimensional angiography

The rest period of the coronary arteries has been shown to be on the order of 120–160 msec. Restriction of the acquisition window in breath-hold cardiac-synchronized gadolinium-enhanced imaging to this duration limits the amount of sampled k-space data and hence the information when compared with conventional gadolinium-enhanced imaging. Two techniques for gadolinium-enhanced cardiac-synchronized angiography were implemented that acquire additional data during the unused portions of the cardiac cycle. Data acquisition is synchronized with the heart cycle and is restricted to a short period of each heart cycle. In a single breath-hold, a multi-slab acquisition (n = 5) allowed ECG-synchronized imaging of the entire heart or a CINE acquisition (n = 5) provided multiple stacks of images at different phases in the cardiac cycle over a smaller area. Preliminary results acquired in healthy volunteers and patients with aortic disease indicate that additional information can be acquired without an increase in breath-hold duration or a reduction in image quality.     

New aminomethylphosphines with cyanophenyl substituents at the nitrogen atoms

A condensation of bis(hydroxymethyl)arylphosphines with 3- and 4-aminobenzonitriles leads to the corresponding 3,7-diaryl-1,5-bis(cyanophenyl)-1,5-diaza-3,7-diphosphacyclooctanes. Acyclic (aryl)bis[N-(2-cyanophenyl)aminomethyl]phosphines are formed in the case of 2-aminobenzonitrile. Molecular and crystalline structure of the compounds obtained was studied by X-ray diffraction analysis.     

Synthesis and Complexation Studies of Various Precursors Based on Calix[4]arene-crown-5 and -6 for the Immunoanalysis of Potassium and Caesium Ions

In an attempt to generate antibodies for the development of an immunoanalysis method for potassium and caesium ions, new 1,3-alternate calix[4]arenes-crown-5 and -6 bearing either carboxylic or hydroxyl functions were synthesized in good yields. Their complexation properties towards potassium and caesium ions were investigated using ¹H NMR spectroscopy and the usual properties proved to be preserved in the presence of the anchoring arms.     

Electrochemical evaluation of a number of nickel complexes with P,N-heterocyclic ligands as catalysts for hydrogen oxidation/release

The efficiency of a series of nickel complexes of P,N-cyclic ligands (potential catalysts in hydrogen fuel cells) in the electrocatalytic reduction of H+ to hydrogen and the oxidation of H₂ in the coordination shell/cavity of the catalyst in DMF (acetonitrile with variable nickel: ligand ratio (1: 1, 1: 2) and different counterions (X=Cl⁻ and BF₄⁻)) was tested, and the most favorable conditions and structures were determined. The relation between the activity of the catalysts and the values of the electrochemical gap was found.     

Sweeping total reflection X-ray fluorescence optimisation to monitor the metallic contamination into IC manufacturing

Among the methods available on the market today to control as metallic contamination in integrated circuit manufacturing, Sweeping Total reflection X-ray Fluorescence mode appears a very good method, providing fast and entire wafer mapping. With the goal of a pertinent use of Sweeping Total reflection X-ray Fluorescence in advanced Integrated Circuit manufacturing this work discusses how acceptable levels of contamination specified by the production (low levels to be detected) can be taken into account.