Tetronomycin, C34H50O8, isolated from a strain of Streptomyces sp. nov. represents a novel polycyclic ionophore polyether. The crystal structure and absolute configuration were established by X-ray analysis of the mono-O-acetyltetronomycin silver salt. Tetronomycin is the first metabolic polyether which contains a tetronic acid moiety instead of the essential carboxylic acid function. A trisubs...

The importance of accurate, reliable recording mediums cannot be understated. Function and esthetics are directly related to this critical step. Dental recording materials must be accurate, easily manipulated, and economical for effective use. Five types of intraoral records of 31 patients were registered and placed on an arcon, semiadjustable articulator to measure the magnitude and direction ...

We present the results of kinetic Monte Carlo simulations aimed at exploring the effect of copolymer sequence distribution on the dynamics of phase separation of an immiscible A/B binary homopolymer blend. Diblock, protein-like copolymers (PLCs), simple linear gradient, random, and alternating copolymers having equal number of A and B segments, identical chemical composition, and chain length a...

Water-soluble copolymers of N-acryloyl-N′-ethylpiperazine (AcrNEP) with methyl methacrylate (MMA) were synthesized to high conversion by free-radical solution polymerization. The composition of the copolymers was determined using Fourier Transform Infra-red Spectroscopy (FTIR). Copolymers containing AcrNEP content above 44 mol% were readily soluble in water and exhibited the critical solution t...

We investigate the pretilt characteristics of a nematic liquid crystal [LC] in terms of ion beam exposure conditions on the homeotropic polyimide alignment layer. The pretilt angle of LCs in the case of high-energy ion beam treatment was decreased considerably almost the same to that of the homogenous alignment layer though we used homeotropic polyimide film at first. Increasing irradiating ene...

Properties of copolymers are generally influenced by the structure of the monomers and polymers. For the purpose of understanding the effect of polymer structure on the properties, two kinds of copolymers, poly(3,4-dihydroxyphenylalanine)-g-polylactide and poly(3,4-dihydroxyphenylalanine)-b-polylactide (PDOPA-g-PLA and PDOPA-b-PLA) were designed and prepared by ring-opening polymerization of la...

2-(Dimethylamino)ethyl methacrylate/styrene statistical copolymers (poly(DMAEMA-stat-styrene)) with feed compositions fDMAEMA = 80–95 mol%, (number average molecular weights Mn = 9.5–11.2 kg mol) were synthesized using succinimidyl ester-functionalized BlocBuilder alkoxyamine initiator at 80 °C in bulk. Polymerization rate increased three-fold on increasing fDMAEMA = 80 to 95 mol%. Linear Mn in...

in atom transfer radical polymerization (atrp) of methyl acrylate (ma) with polyvinyl acetate macroinitiator in bulk at 90°c the plots of ln [m]0/[m] increased linearly with reaction time. the apparent propagation rate constant (kp app) of the reaction was obtained from the linear curve and used to calculate the free macroradical concentration ([r°]) in polymerization medium. the [r°] and also ...

purpose: to evaluate the efficacy of silicone oil injection after deep vitrectomy in infectious endophthalmitis regarding visual acuity. methods: this single-blind randomized clinical trial was performed on 50 cases of infectious endophthalmitis undergoing deep vitrectomy. patients were randomly assigned to two groups: in one group silicone oil was injected into the eye at the end of the operat...

OBJECTIVE To determine whether prior silicone injection increases the risks associated with carbon dioxide laser resurfacing. DESIGN Laboratory determination of the effect of laser energy on liquid silicone; histologic evaluation of silicone-injected skin after lasing; and histologic demonstration of silicone deposits in all layers of dermis years after injection of silicone as filler fluid. ...