Modification of Acrylic Fibers: An Overview

Abstract

Among the vinyl monomers, acrylonitrile is the only monomer used for the production of synthetic fibers. Other vinyl monomers lack cohesive forces between the molecular chains of their polymers and, hence, can not compete with acrylonitrile [1]. Acrylic fiber has replaced wool in many major applications, particularly in hand knitting and hosiery garments. The majority of knitting yarns are usually bulky yarns which go into the manufacture of pullovers, sweaters, socks, etc. Acrylic fiber has been able to replace wool considerably in these applications. Blankets and carpets are other applications where acrylic fiber competes with wool [2] because of its high elasticity, color brilliancy, volumenosity, easy shampooing, resistance to pilling, good light and colorfastness values, etc.     

Novel method for order parameter of ferroelectric liquid crystals by image analysis

A novel method for temperature dependence of order parameter calculations at different wavelengths through birefringence measurements for ferroelectric liquid crystals (S)-(-)-2-methylbutyl 4′-(4″-n-alkanoyloxy benzoyloxy) biphenyl-4-carboxylates (where n?=?16 and 18) has been proposed using image analysis and linear regression method of Kuczynski equation. Measurements are made for its liquid crystal phases (SmecticC*, SmecticA) to the isotropic phase of the sample. The birefringence values of the samples at different wavelengths are obtained from the textural analysis of liquid crystal as a function of temperature using MATLAB software.     

Efficient Synthesis of Aryl‐14H‐dibenzo[a.j]xanthenes using NaHSO4‐SiO2 or 5%WO3/ZrO2 as Heterogeneous Catalysts under Conventional Heating in a Solvent‐Free Media

A simpler and greener protocol has been developed for the preparation of aryl‐14H‐dibenzo[a.j]xanthenes: a one‐pot condensation of β‐naphthol and aryl aldehydes, in the presence of silica‐supported sodium hydrogen sulfate (NaHSO₄ · SiO₂) or tungstated zirconia (5%WO₃/ZrO₂) as heterogeneous catalysts in a solvent‐free media. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times (2–8 h), and milder conditions.     

On The Protection of 3α-Hydroxy Group of A/B cis Steroids

The difficulties encountered in the protection of 3α-hydroxy group of lithocholic acid 1 with three different types of protective groups are described. Only benzyl ether derivative was found to be suitable for synthetic transformations. The methodology for the synthesis of benzyl ethers of A/B cis steroids is reported for the first time.     

Radiosynthesis and in vitro evaluation of 99mTc(CO)3-labeled folic acid derivative

The over-expression of folate receptors in variety of neoplastic tissues makes radiolabeled folate conjugates potential agents for imaging and therapy of such cancers. With the aim of preparing an imaging agent for targeting folate receptors, folic acid has been conjugated with homocysteine for complexation with [^99mTc(CO)₃(H₂O)₃]⁺ core. The radiolabeled complex of the homocysteine-folate could be obtained in >95% radiochemical yield as observed by HPLC. Stability of complex in saline was studied and challenge studies with histidine and cysteine revealed kinetic stability of the complex. Lipophilicity of the radiolabeled complex (log P) was found to be 0.45. In vitro uptake of ^99mTc(CO)₃-labeled folic acid derivative was studied in KB cells and inhibition studies were carried out using ³H-folic acid and cold homocysteine–folate conjugate. The in vitro studies indicated loss of binding affinity of the derivative towards folate receptors.     

Cyclohexanol dehydrogenation over Cu-loaded TiO2 photocatalyst under solar illumination

Abstract  

The liquid-phase selective dehydrogenation of cyclohexanol has been investigated using two classes of catalyst containing either Cu₂O or CuO on TiO₂ under solar light in deaerated conditions at room temperature using acetonitrile medium in a batch reactor. The effect on dehydrogenation of three conditions, cyclohexanol concentration, copper loading on TiO₂, and amount of catalyst, were investigated. The maximum yield of cyclohexanone obtained was 40%. The catalysts were characterized by XRD, UV–DRS, TEM, SEM–EDAX, and XPS. It was found that 1% (w/w) Cu₂O/TiO₂ was 100% selective for photocatalytic dehydrogenation of cyclohexanol.