Volumetric iodate method for the determination of thiocyanate

Direct titration of thiocyanate with standard potassium iodate solution is found to yield accurate results in a final hydrochloric acid concentration regulated between 1.5 and 3N. The end-point is determined either potentiometrically or with carbon tetrachloride indicator.     

Surface Modification of Ultra-high Molecular Weight Polyethylene Membranes Using Underwater Plasma Polymerization

Ultra-high molecular weight polyethylene membranes were modified and subsequently polymer coated using the underwater plasma produced by glow discharge electrolysis. This plasma pretreatment generated various O-functional groups among them OH groups have dominated. This modified inner (pore) surface of membranes showed complete wetting and strong adhesion to a hydrogel copolymerized by glow discharge electrolysis also. The deposited hydrogel consists of plasma polymerized acrylic acid crosslinked by copolymerization with the bifunctional N,N′-methylenebis(acrylamide). Tuning the hydrogel hydrophilicity and bio-compatibility poly(ethylene glycol) was chemically inserted into the copolymer. Such saturated polymer could only be inserted on a non-classic way by (partial) fragmentation and recombination thus demonstrating the exotic properties of the underwater plasma. The modification of membrane was achieved by squeezing the reactive plasma solution into the pores by plasma-induced shock waves and supported by intense stirring. The deposited copolymer hydrogel has filled all pores also in the inner of membrane as shown by scanning electron microscopy of cross-sections. The copolymer shows the characteristic units of acrylic acid and ethylene glycol as demonstrated by infrared spectroscopy. A minimum loss in carboxylic groups of acrylic acid during the plasma polymerization process was confirmed by X-ray photoelectron spectroscopy. Additional cell adhesion tests on copolymer coated polyethylene using IEC-6 cells demonstrated the bio-compatibility of the plasma-deposited hydrogel.     

Aqueous Aza-Michael Reaction of Conjugated Alkenes: Toward Spermine

An aqueous aza-Michael reaction is efficiently achieved with excellent conversions without any additives. The method works very well on a molar scale with selectively for aliphatic amines. An intermediate for spermine is also made by this green process.     

A New Generalized Bond Energy/Group Contribution Scheme for Calculating the Standard Heat of Formation of Monomers and Polymers. Part V. Oxygen Compounds

Abstract

The new generalized bond energy scheme has been extended to organic oxygen compounds. About 50 different types of bonds have been identified and their ΔH_f°(g) contributions and atomization energies evaluated by a procedure similar to multilinear regression analysis. Recent thermochemical data (1969-1973) on 145 oxygen compounds and about 80 ring compounds have been employed to test the efficiency of the scheme in predicting the gas phase heats of formation. This was found to be about ±0. 8 kcal/mole, which is quite comparable to the group contribution method of Benson and co-workers involving a much larger number of parameters.

The typical chemical bonds identified and resolved in respect of their bond energies bear good consistency and correlation with bond lengths and force constants measurable independently. Heats of formation and polymerization on about 47 monomer-polymer systems and enthalpies of other polymeric reactions have been predicted and compared with available experimental data.     

Conductivity as a Sensor for Monitoring Relative Magnesium Corrosion Rates in Real‐time,in Serum‐containing Media under Cell Culture Conditions

Because controlling the corrosion rate of magnesium metal will be crucial to the success of biomedical implants containing pure magnesium or magnesium alloys, many ways have been sought to improve in vitro tests to analyze corrosion rates, and also to identify new methods of preparing or post‐processing magnesium. In this work, for an in vitro assay, we explored the use of a commercially available conductivity sensor to study magnesium corrosion under cell culture conditions that duplicate many physiologically appropriate parameters. With this sensor, we studied the corrosion of two previously untested magnesium single crystal samples that differed in surface treatments that could alter corrosion rates. The results show that the relative conductivity changes in (mS/cm) over the total time of immersion were proportional to the corrosion rates in (mm/y) and also to the total magnesium released, as detected by inductively coupled plasma mass spectrometry (ICP‐MS).     

Persistent luminescence in Ca8Zn(SiO4)4Cl2:Eu2+

A new persistent, green emission is reported for europium activated Calcium Zinc Chlorosilicate (CZCS). The phosphor was prepared by the solid state reaction and characterized using XRD, PL and TL techniques. The decay was characterized by admixture of two exponential components with decay constants 20.2 and 101 s.     

Note High Yield Synthesis of Low Molecular Weight Poly(Vinyl Acetate) in Aqueous Acidic Media

Polymerization of vinyl acetate continues to interest workers in the field as evidenced by recent publications [1–3]. However, little information is available concerning the synthesis of low molecular weight poly(vinyl acetate) (PVAc) despite its industrial importance.     

Influence of an Oxidising Impurity on Preparation of 2-Lithio-1,3-dithiane: Isolation of bis[2-d,3-Dithianyl)]methanol

Bis-dithianylalkanols and dimers are formed in preparation of 2-lithio-1,3-dithianes due to the presence of oxidising impurity in n-BuLi (perhaps n-BuOOLi).