Characterization of the switching parameters in the dual-channel double Heterostructure Optoelectronic switch

A new three-terminal switching device utilizing two modulation-doped heterointerfaces to achieve electron and hole symmetries is investigated. The switching voltage is investigated by varying the critical barrier-doping parameters and capacitor spacings over a range of practical values. The experimental dependence upon current injection into the electron field-effect channel is characterized. Both two- and three-terminal device measurements are compared with a recent theoretical model, and show excellent correlation.     

Thermal expansion of graphite fiber-reinforced metals

The presence of graphite fibers in metal matrices greatly influences the properties of the composites. Graphite fibers have been used in conjunction with aluminum, magnesium, and copper matrices. The type of graphite fiber, layup of the fiber, and volume percentage of the fibers are all important parameters in controlling the properties of the composites. The present status, particularly in the case of graphite/copper, can be considered to be the original developmental stage and is definitely far-removed from a matured technology. The present paper focuses on thermal expansion behavior of several graphite-metal matrix composites from –60 to +200°C.Paper presented at the Tenth International Thermal Expansion Symposium, June 6–7, 1989, Boulder, Colorado, U.S.A.     

Subcellular distribution of dietary β-carotene in chick liver

Studies were conducted examining the subcellular distribution of β-carotene (BC), α-tocopherol (E) and retinol (A) in livers of control and BC-fed male White Leghorn chicks. Chicks were fed Cornell B chick starter diet with or without the addition of 0.5 g BC/kg diet. A first study involved liver fractionation by differential centrifugation in 0.25 M sucrose followed by high performance liquid chromatographic (HPLC) analyses of all fractions for quantitation of BC, E and A. A second study employed both intravenous injection of Triton WR-1339 four days prior to sacrifice and centrifugation in 1.0 M sucrose to separate mitochondria from lysosomes more efficiently. Fraction purity was assessed by marker enzyme analyses. Results showed that (i) chick liver accumulated BC; (ii) BC-fed chicks had higher concentrations of BC in all fractions relative to controls, and (iii) the mitochondrial fraction contained the highest concentration of BC, followed by lysosomes, microsomes and nuclei, respectively. Plasma BC increased more than fivefold in BC-fed chicks. Dietary BC increased A and E levels in liver and in the mitochondrial and lysosomal fractions while the plasma E level was decreased. Plasma A changed little with BC feeding. While dietary BC had no effect on fatty acid composition of subcellular fractions, the increase in E resulted in a large increase in the molar ratio of E to polyunsaturated fatty acids. The incorporation of BC and increased amounts of E into cellular mebranes presumably would result in increased resistance to peroxidative damage.     

Synthesis, and in vitro and in vivo muscarinic pharmacological properties of a series of 1,6-dihydro-5-(4H)-pyrimidinone oximes

A series of 1,6-dihydro-5-(4H)-pyrimidinone oxime derivatives I was synthesized (Scheme 1, Tables 1 and 2) and tested for muscarinic activity (Table 3) in receptor binding assays using [3H]-oxotremorine-M (Oxo-M) and [3H]-pirenzepine (Pz) as ligands. Potential muscarinic agonistic or antagonistic properties of the compounds were determined using binding studies that measured their potencies to inhibit the binding of Oxo-M and Pz. Preferential inhibition of Oxo-M binding was used as an indicator for potential muscarinic agonistic properties; this potential was confirmed in functional studies on isolated organs. The series produced a wide range of active compounds with differing degrees of selectivity in M1, M2, and M3 functional models. Several compounds that have mixed agonist/antagonist profiles were able to reduce cholinergic-related cognitive impairments in models of mnemonic function. Substitutions (I, e.g. R2 or R3 = Me) at the 1,6-dihydro-5-(4H)pyrimidine ring disrupted binding and efficacy, whereas systematic variation of the oximes substituent R1 resulted in various degrees of potency and selectivity dependent on the nature of the substitution.     

Establishment of hormone-dependent and hormone-independent carcinoma cell lines with different metastatic potentials from spontaneous mammary tumors in aged Wistar rats

Three stable carcinoma cell lines, designated RM22-F5, RM17-5R, and RM1-4, were established from spontaneously occurring mammary carcinomas in old, outbred, female Wistar rats. The RM22-F5 and RM17-5R cells were keratin-positive and formed epithelial monolayers, whereas RM1-4 cells exhibited a spindle-like morphology and intense vimentin staining. When injected into nude mice, RM22-F5, RM17-5R and RM1-4 cells formed well-differentiated, poorly differentiated and undifferentiated carcinomas, respectively. The relative growth rates of the tumor cells in vitro were RM1-4 > RM22-F5 > RM17-5R. The growth of RM22-F5, but not of RM17-5R and RM1-4 cells, was significantly stimulated by insulin, epidermal growth factor, dexamethasone, 17 beta-estradiol and progesterone in vitro. Ovariectomy reduced the growth of RM22-F5 cells in vivo and these cells (but not RM1-4 or RM17-5R) were estrogen-receptor (ER)-positive. None of the lines were positive for the progesterone receptor (PR). Spontaneous lung and lymph-node metastases were observed in nude mice injected with RM22-F5 or RM17-5R cells, respectively. In contrast, RM1-4 cells were non-metastatic but invasive. Karyotype analysis revealed that RM22-F5 cells were hyperdiploid, RM17-5R were hypotetraploid, and RM1-4 were diploid with a sizeable insertion in chromosome 1. A point mutation in codon 12 (G to A transition) and loss of the normal allele of the H-ras-1 gene was detected in the DNA from RM22-F5 cells. No p53 mutations were apparent in any of the cell lines. The results indicate that RM22-F5 cells are hormone-dependent with an ER+/PR- phenotype, while the RM17-5R and RM1-4 lines are hormone-independent and ER-/PR-. These cell lines exhibit the spectrum of biological properties and genetic alterations observed in human breast cancers and may, therefore, be novel and useful models for understanding sporadic breast cancer in post-menopausal women.     

Worries and obsessions in individuals with obsessive-compulsive disorder with and without comorbid generalized anxiety disorder

Participants from the DSM-IV field trial for OCD (N = 381) were divided into two groups based on the SCID interview: those who met current criteria for obsessive-compulsive disorder (OCD) but not generalized anxiety disorder (GAD) and those who met current diagnostic criteria for both. The groups were compared on their severity of obsessive and compulsive symptoms, as well as on the percent of individuals who reported excessive worry concerning everyday issues (e.g. health, finances). The comorbidity rate was 20%. While the presence of GAD did not elevate OCD symptoms per se, it was associated with more pathological responsibility and indecisiveness. Excessive worries were significantly more common in those with comorbid OCD and GAD. The relationship between obsessions and worries is discussed.