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  • 1
    Electronic Resource
    Electronic Resource
    Modeling and characterization of a strained Si/Si1−xGex transistor with δ-doped layers (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 1443-1448 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A two-dimensional model of a strained Si/Si1−xGex transistor with δ-doped layers was developed. A semiclassical drift diffusion model is used to study the effects of different conduction-band offsets and variation of the distance between the Si channel and an n-type δ-doped layer as well as the thickness of this δ-doped layer at room temperature. We found that a large conduction-band offset, or a large Ge concentration, confines electrons more strongly to the Si channel. These factors raise the drain current when the doping level per unit area is constant. The area between the Si channel and the δ-doped layer and the δ-doped layer itself forms a barrier to electrons donated by the donor atoms in the δ-doped layer. Hence, the smaller the distance between the Si channel and the δ-doped layer and the thinner the δ-doped layer, the larger the number of electrons in the Si channel. Through the present analysis, an optimum design concept is clarified for device applications of Si/Si1−xGex systems. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.370909
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  • 2
    Electronic Resource
    Electronic Resource
    Theoretical study of tunneling current in the access region of various heterojunction field-effect transistor structures (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 3603-3607 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The source resistance of a heterojunction field-effect transistor (HFET), whose reduction is mandatory for high-performance devices, consists of an ohmic contact resistance and an access resistance. The access region is located between the geometrical source and the geometrical source side of the gate contact. By means of a quantum-mechanical modeling program, the effect of changes in layer structure in the access region of a HFET is studied. A new heterojunction structure using a Si planar doped layer is designed to improve the linearity and reduce the access resistance by more than ten times for a specific transistor layout. Thanks to the higher sensitivity of the modeling program to structural information, the contribution of the tunneling current and the change of equilibrium as a function of temperature is investigated. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361414
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  • 3
    Electronic Resource
    Electronic Resource
    Differential Expression of NGFI-B and RNR-1 Genes in Various Tissues and Developing Brain of the Rat: Comparative Study by Quantitative Reverse Transcription-Polymerase Chain Reaction (1997)
    Oxford : Blackwell Science Ltd.
    Journal of neuroendocrinology 9 (1997), S. 0 
    Details
    ISSN: 1365-2826
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: NGFI-B and RNR-1 are closely related transcription factors that constitute a distinct subclass within the steroid/thyroid hormone receptor superfamily. They have been implicated in neuronal differentiation, neuroendocrine regulation of adrenocortical function and T-cell apoptosis. In this study, we measured and compared NGFI-B and RNR-1 mRNA levels in various adult rat tissues and in the developing rat brain by means of the quantitative reverse transcription-polymerase chain reaction. The use of RNA standards synthesized in vitro allowed direct comparison of the amount of the transcripts of these two genes. We demonstrated that the transcripts of both genes were present in all tissues examined although the expression levels widely varied. We found the highest constitutive expression of both genes in the pituitary. High levels of NGFI-B were also expressed in the cerebral cortex, muscle, ventral prostate, thymus and adrenal glands, whereas high levels of RNR-1 expression were restricted to the pituitary and cerebral cortex. These findings were consistent with the notion that NGFI-B and RNR-1 are involved in various signal transduction systems in diverse cell types. The amount of NGFI-B mRNA was greater than that of RNR-1 mRNA in all adult rat tissues, with the highest ratio of NGFI-B relative to RNR-1 expression in the muscle and leukocytes. In contrast, fetal rat brain showed relatively high RNR-1 gene expression. These findings suggested that the NGFI-B and RNR-1 genes are differentially expressed in a tissue-specific and developmentally regulated manner.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2826.1997.00571.x
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  • 4
    Electronic Resource
    Electronic Resource
    Pharmacokinetics and pharmacodynamics of a novel protein kinase inhibitor, UCN-01 (1999)
    Springer
    Cancer chemotherapy and pharmacology 44 (1999), S. 12-18 
    Details
    ISSN: 1432-0843
    Keywords: Key words 7-Hydroxystaurosporine (UCN-01) ; Pharmacokinetics ; Pharmacodynamics ; HPLC
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Purpose: 7-Hydroxystaurosporine (UCN-01) is a potent protein kinase inhibitor and is being developed as a novel anticancer agent. We describe here its pharmacokinetics and pharmacodynamics in experimental animals. Methods: The pharmacokinetics of UCN-01 were studied following intravenous (i.v.) administration to mice, rats and dogs at doses of 1–9, 0.35–3.5 and 0.5 mg/kg, respectively. We also studied the pharmacodynamics of UCN-01 (9 mg/kg per day) during and after five consecutive i.v. administrations to nude mice bearing xenografted human pancreatic tumor cells (PSN-1). The concentrations of UCN-01 in plasma and tumor were measured by HPLC using a fluorescence detector. Results: UCN-01 in plasma after i.v. administration was eliminated biphasically in mice and rats, and triphasically in dogs. The elimination half-lives in mice, rats and dogs were 3.00–3.98, 4.02–4.46 and 11.6 h, respectively. The total clearance (Cltotal) values in mice, rats and dogs were high (1.93–2.64, 2.82–3.86 and 0.616 l/h per kg, respectively). The hepatic clearance (Clhepatic) in rats represented 54.0–81.3% of Cltotal. The volumes of distribution at steady-state in mice, rats and dogs were large (7.89–8.42, 13.0–16.9 and 6.09 l/kg, respectively). These pharmacokinetic parameters were dose-independent in mice and rats. UCN-01 produced significant inhibition of tumor growth during five consecutive i.v. administrations in mice bearing the xenografted PSN-1 cells, and the inhibitory effect continued for 3 days after the final administration. UCN-01 concentrations in tumor tissue were much higher than those in the plasma, and the ratio of tumor to plasma concentrations was about 500 at 24 h after five consecutive doses. Conclusions: The pharmacokinetic studies showed that UCN-01 has a high clearance and large distribution volume in various experimental animals, and its disposition is linear over the range of doses tested. The pharmacodynamic study showed that UCN-01 is distributed at much higher concentrations in tumor than those in plasma and that it significantly inhibits tumor growth. The high distribution of UCN-01 into tumor cells may contribute to the potent inhibition of tumor growth in vivo.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002800050939
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  • 5
    Electronic Resource
    Electronic Resource
    Enhanced NOR-1 gene expression by exposure of Chinese hamster cells to high-density 50 Hz magnetic fields (1998)
    Springer
    Molecular and cellular biochemistry 181 (1998), S. 191-195 
    Details
    ISSN: 1573-4919
    Keywords: extremely low frequency magnetic fields ; gene expression ; neuron derived orphan receptor-1 ; signal transduction ; Chinese hamster ovary K1 cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Enhanced expression of neuron derived orphan receptor (NOR-1) gene was observed by exposure of Chinese hamster ovary K1 (CHO-K1) cells to an extremely low frequency magnetic field (ELFMF) of 50 Hz at 400 mT, but not at 5 mT. The enhanced expression, reaching the maximum at 6 h, was transient and reduced to the control level after exposure to 400 mT ELFMF for 24 h. The NOR-1 expression induced by treatment with forskolin and TPA was further enhanced by the simultaneous treatment with 400 mT ELFMF, in which the maximum response was at 3 h. The NOR-1 expression by these treatments was induced more earlier than that by 400 mT ELFMF alone. When cells were treated with an inhibitor of the protein kinase C (calphostin C or crocetin) and Ca2+ entry blockers (nifedipin and dantrolen) during the 400 mT ELFMF exposure, the enhanced NOR-1 expression was not observed. Exposure of CHO-K1 cells to the high-density 400 mT ELFMF may affect the signal transduction in the cells, resulting in the enhanced NOR-1 gene expression.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006828400868
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  • 6
    Electronic Resource
    Electronic Resource
    Immunocytochemical localization of annexin 5, a calcium-dependent phospholipid-binding protein, in rat endocrine organs (1998)
    Springer
    Cell & tissue research 292 (1998), S. 85-89 
    Details
    ISSN: 1432-0878
    Keywords: Key words Annexin 5 ; Immunocytochemistry ; Pituitary ; Ovary ; Testis ; Adrenal gland ; Thyroid gland ; Rat (wistar)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Annexin 5, a unique calcium- and phospholipid-binding protein, has been investigated for its specific distribution in rat endocrine organs by immunocytochemistry with a specific antiserum to recombinant rat annexin 5. Follicular epithelial cells and parafollicular cells of the thyroid gland, adrenocortical cells of the zona fasciculata and zona reticularis, luteal cells, testicular interstitial cells, and Sertoli cells were shown to contain annexin 5. To examine whether the synthesis of annexin 5 would be affected by a change in humoral signal, the distribution of annexin 5 in the anterior pituitary was examined three weeks after ovariectomy. The withdrawal of ovarian hormones induced huge castration cells in the anterior pituitary gland, which contained abundant annexin 5. Annexin 5 was not detected in the pineal gland, the parathyroid gland, the islet of Langerhans, the adrenal medulla, zona glomerulosa cells, and granulosa cells. Since annexin 5 was shown to exist in many of the endocrine tissues examined, to be localized in specific cell types, and to be abundant in castration cells, it is suggested that annexin 5 contributes to secretory cell functions, which may be common to endocrine cells secreting chemically different hormones.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004410051037
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