Zone drawn NEW-TPI thermoplastic polyimide and its blends with Xydar liquid crystalline polymer

In this work we report the effects of single stage zone drawing on the properties of NEW-TPI thermoplastic polyimide homopolymer, and its blends with Amoco's Xydar liquid crystalline polymer. Zone drawing was performed first on homopolymer NEW-TPI films to determine the effect of load weight, heater speed, and drawing temperature on the attainable draw ratio. Degree of crystallinity and chain orientation increase as the draw ratio increases for NEW-TPI. Blends of NEW-TPI/Xydar compositions 90/10 and 70/30 were studied next. In blends, the Xydar component is not molecularly dispersed, and is initially preferentially oriented along the machine direction during the film processing stage. Xydar acts as a nucleation site and lowers the temperature for crystallization of the NEW-TPI from the rubbery amorphous state. Zone drawing was performed either parallel or perpendicular to Xydar's initial preferred orientation direction. Blends with lower Xydar fraction could be zone-drawn to higher ratios. Zone drawing perpendicular to Xydar's initial orientation direction also resulted in increased draw ratio. Dynamic mechanical properties of the zone drawn materials were studied. In homopolymer NEW-TPI, dynamic modulus increased by a factor of two to 4.0 GPa in zone drawn films, largely as a result of the formation of oriented crystallites. In the blends, the modulus parallel to Xydar's initial orientation direction was greater than that in the transverse direction. Depending upon composition and test direction, zone drawing increased the dynamic moduli of the blends from 1.5 up to 2.7 times, in the temperature range from 150°C to 300°C.     

ASGPR‐Mediated Uptake of Multivalent Glycoconjugates for Drug Delivery in Hepatocytes

Liver cells are an essential target for drug delivery in many diseases. The hepatocytes express the asialoglycoprotein receptor (ASGPR), which promotes specific uptake by means of N‐acetylgalactosamine (GalNAc) recognition. In this work, we designed two different chemical architectures to treat Wilson's disease by intracellular copper chelation. Two glycoconjugates functionalized with three or four GalNAc units each were shown to enter hepatic cells and chelate copper. Here, we studied two series of compounds derived from these glycoconjugates to find key parameters for the targeting of human hepatocytes. Efficient cellular uptake was demonstrated by flow cytometry using HepG2 human heptic cells that express the human oligomeric ASGPR. Dissociation constants in the nanomolar range showed efficient multivalent interactions with the receptor. Both architectures were therefore concluded to be able to compete with endogeneous asialoglycoproteins and serve as good vehicles for drug delivery in hepatocytes.     

NEW-TPI thermoplastic polyimide: Structure and relaxation using SAXS and TSDC

The thermoplastic polyimide Regulus^TM NEW-TPI has been studied using small-angle X-ray scattering (SAXS) and thermally stimulated depolarization current (TSDC). SAXS was used to study the development of lamellar structure during isothermal or nonisothermal crystallization. The one-dimensional electron-density correlation function was used to determine structural parameters. The long period, lamellar thickness, and amorphous layer thickness increase as crystallization temperature increases from 300 to 360°C. By combining melting-point data with SAXS results, we report the side and fold surface free energies of NEW-TPI crystals, which are 29 ± 3 and 41 ± 3 erg/cm², respectively. Real-time SAXS was carried during nonisothermal cold-crystallization at 5°C/min. The long period decreases, while lamellar thickness, linear crystallinity, and interphase thickness increase, with increasing temperature. These changes are explained by a crystal-insertion model. TSDC was used as a more sensitive probe of the amorphous phase structure below 300°C. Both semicrystalline and amorphous NEW-TPI exhibit complex TSDC behavior. Above the glass transition, amorphous NEW-TPI has a strong TSDC peak attributed to short-range-ordered structures, which may serve as nucleation sites for subsequent crystallization. This peak was not seen in semicrystalline material. At the glass transition, both amorphous and semicrystalline NEW-TPI have a strong TSDC peak. In the semicrystalline polymer, relaxation of the amorphous dipoles is slightly restricted by the crystals, which results in a smaller relaxation peak and a shift to higher temperature. Below T_g, another TSDC peak occurs which is not due to dipolar relaxation. This peak is attributed to the combined effects of space charge, electrode type, ionizable species, and interfacial charges. © 1995 John Wiley & Sons, Inc.     

Roles of approval motivation and social reinforcement in children's discrimination learning.

144 3rd- and 4th-grade children were given a 2-choice discrimination learning task. The 2 major factors were (a) the 3 levels of social desirability (high, moderate, and low) on the Children's Social Desirability scale; and (b) the 2 types of treatment conditions (monetary-social reinforcement and monetary-no social reinforcement). In opposition to D. P. Crowne and D. Marlowe's (1961) model of the approval-motivated individual, the high-social-desirability group made significantly fewer errors than both the moderate and low groups. It is suggested that for young children, social desirability scores may require a different interpretation than scores for older children and adults. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Encoding of instruments when 10- to 14-year-olds process isolated instrument-implicit sentences: More evidence of improved encoding during childhood resulting from elaborative instructions.

Examined whether 10- to 14-yr-olds infer implied instruments when reading isolated instrument-implicit sentences (IISs; e.g., Her friend swept the floor) as certainly and completely as they do when instructed to generate instruments in response to IISs. On-line instrumental encoding was tested with a procedure that was based on recognition priming of instrument words given some of the letters from the words (i.e., a word fragment). When children read the IISs without instruction to infer the implied instruments, the instrument fragment completion rates were low and less than when inference generation was required or instruments were stated during reading. Children's spontaneous instrumental inferences are less certain than suggested in previous research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rehospitalization of schizophrenics as a function of intelligence.

Reports that brighter schizophrenic Ss were less often rehospitalized 3 and 5 yrs after discharge than Ss of less than median IQ. It is concluded that the prognostic significance of IQ contributes to differences in intelligence between acute and chronic hospitalized schizophrenics and poses serious difficulties for the study of differential deficits in cognitive abilities in these groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stress, expectancies, and vulnerability to substance abuse: A test of a model among homosexual men.

We hypothesize that specific attitudes or expectancies make people vulnerable to responding to stress via alcohol or drugs. This "stress-vulnerability" model was tested among homosexual men, who show elevated rates of substance abuse and have culturally specific stressors and vulnerability. Tension reduction expectancies of alcohol effects had a substantial effect on alcohol and marijuana/drug abuse, as did the use of bars as a social resource. Two stress variables—negative affectivity and discrimination attributable to sexual orientation—also had significant, though more moderate effects. Interactions of the vulnerability measures with the stress variables had significant effects on substance abuse beyond the main effects, supporting the central hypothesis. In a second analysis both simple consumption levels and "high-risk" styles of alcohol or drug use predicted alcohol or drug problems better among vulnerable than among nonvulnerable respondents. These findings strongly supported a general stress-vulnerability model of substance abuse and illustrated several important risk factors in homosexual culture. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does switching to low tar/nicotine/carbon-monoxide-yield cigarettes decrease alveolar carbon monoxide measures? A randomized controlled trial.

Assessed the effects of changing to low tar/nicotine/carbon-monoxide-(CO)-yield cigarettes on alveolar carbon monoxide over a 5–6 wk period for 40 adult chronic smokers of high tar/nicotine/CO cigarettes. Ss were assigned to either a 5-wk step-wise brand-reduction treatment or to a delayed-treatment control group. Ss were assessed for (a) resting CO body burden and CO uptake per cigarette and (b) smoking topography and rate. Although CO uptake was significantly lower after Ss smoked low tar/nicotine/CO cigarettes than after smoking their original brand, resting CO body burden did not change. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)