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  • Springer  (34)
  • American Physical Society (APS)  (10)
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  • 1
    Electronic Resource
    Electronic Resource
    Large area InAlAs/InGaAs metal semiconductor metal photodiode with very low dark current and its frequency response (1997)
    Springer
    Optical and quantum electronics 29 (1997), S. 953-959 
    Details
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract An MBE grown InGaAs metal semiconductor metal (MSM) photodiode (PD) with an InAlAs barrier enhancement layer is reported that has very low dark current and high speed characteristics. The detector using Cr/Au Schottky metal fingers with 4m spacing on a large active area of 300×300m2 shows a low dark current of 38nA at 10V. This corresponds to a dark current density of 0.42pA/m2 and is, to our knowledge, the best dark current ever obtained from a large area InGaAs MSM PD. The device also shows a low capacitance of 0.8pF and a high 3dB bandwidth of 2.4GHz. By fitting the measured frequency response to a model consisting of both RC time and transit time limited responses, we show that the device has an RC time and a transit time limited 3dB bandwidth of 3.0 and 4.9GHz, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018589903010
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  • 2
    Electronic Resource
    Electronic Resource
    Feasibility study on the use of calcium alginate-entrapped hybridoma cells for IgM production (1995)
    Springer
    Bioprocess and biosystems engineering 12 (1995), S. 65-70 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In order to test the feasibility of using calcium alginate-entrapped hybridoma cells for IgM production, HO-22-1 hybridoma cells entrapped into calcium alginate beads with varying alginate concentrations were cultivated in spinner flasks. It was observed that the IgM produced by the entrapped cells could diffuse out of the calcium alginate beads regardless of alginate concentrations tested (0.8–2.5%). Since the increase in alginate concentrations showed an adverse effect on cell growth and maximum cell concentration, the use of lower alginate concentration was desirable for higher volumetric monoclonal antibody (MAb) productivity. When the entrapped cells in 0.8% alginate beads were cultivated in repeated-fed batch mode, the reduction of serum concentration in the medium from 10% to 1% did not decrease the volumetric IgM production. Taken together, the data obtained here showed the feasibility of using calcium alginate-entrapped hybridoma cells for IgM production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01112995
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  • 3
    Electronic Resource
    Electronic Resource
    Amylase Polymorphism of Littorina brevicula from Polluted and Unpolluted Sites, Korea (1999)
    Springer
    Bulletin of environmental contamination and toxicology 63 (1999), S. 633-638 
    Details
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001289901027
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  • 4
    Electronic Resource
    Electronic Resource
    Expression of the tumor necrosis factor α gene and early response genes by nodularin, a liver tumor promoter, in primary cultured rat hepatocytes (1997)
    Springer
    Journal of cancer research and clinical oncology 123 (1997), S. 413-419 
    Details
    ISSN: 1432-1335
    Keywords: Key words Tumor necrosis factor α ; Early-response genes ; Liver carcinogen ; mRNA stabilization ; Protein phosphatase inhibitor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Nodularin is a new liver carcinogen possessing a potent tumor-promoting activity in rat liver, mediated through inhibition of protein phosphatases 1 and 2A, and a weak initiating activity. Since we previously reported evidence that nodularin up-regulated expression of the tumor necrosis factor α gene (TNFα) and early-response genes in rat liver after its i.p. administration, and since TNFα had tumor-promoting activity in vitro, it is possible that TNFα itself is involved in liver tumor promotion. We investigated whether hepatocytes themselves induce expression of the TNFα gene and early-response genes in primary cultured rat hepatocytes treated with nodularin. Like nodularin, microcystin-LR, which is another liver tumor promoter belonging to the okadaic acid class, strongly induced TNFα gene expression in rat hepatocytes, as well as TNFα release from those cells into the medium. On the other hand, 12-O-tetradecanoylphorbol-13-acetate, which has been reported to induce no tumor promotion in rat liver, induced no apparent expression of the TNFα gene in primary cultured rat hepatocytes. As for the expression of early-response genes, 1 μM nodularin or microcystin-LR induced expression of the c-jun,  jun B, jun D, c-fos, fos B and fra-1 genes in the hepatocytes, and the expression of these genes was prolonged up to 24 h, suggesting mRNA stabilization induced by inhibition of protein phosphatases 1 and 2A. This paper presents new evidence that the TNFα gene and early-response genes were expressed in hepatocytes treated with a liver tumor promoter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01372544
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  • 5
    Electronic Resource
    Electronic Resource
    Paracrine factors and the regulation of spermatogenesis (1993)
    Springer
    World journal of urology 11 (1993), S. 120-128 
    Details
    ISSN: 1433-8726
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Main problem: Although the gonadotropins and testosterone are required for normal spermatogenesis, it is believed that local control factors regulate spermatogenesis. For many years these regulatory factors had not been identified. Over the past five years, a number of growth factors have been identified in testis or isolated testicular cell types or secretions. Growth factors are key regulatory molecules which affect cell proliferation, meiosis, and differentiated function. These factors usually act in an autocrine (acting upon the cell which secreted it) or paracine (affecting another cell) manner and thus are involved in intercellular communications. Methods: Growth factor secretion by testicular cell types or testis tissue has been analyzed using a variety of assays measuring cell proliferation in vitro, as well as assays using immunocytochemicals. Growth factor gene expression in testis has been analyzed by Northern blot analysis and in situ hybridization, which gives information concerning the stage and cell specific expression of the gene. Inbred strains of mice with mutations or deletions in a growth factor gene has been used to suggest the function of two specific factors in testicular development and growth. Results: Among the growth factors expressed or secreted by testicular cell types, most are common to some other cell types in the body, such as transforming growth factors alpha and beta, epidermal growth factor, fibroblast-like growth factors, insulin-like growth factors, interleukins, endorphins, inhibin and activin, while others may be more testis specific such as mullerian inhibiting substance (anti-mullerian hormone) and Sertoli cell secreted growth factor. A variety of proto-oncogenes are expressed at discrete stages of spermatogenesis, as well as by the somatic cells of the testis. Many of these encode growth factors, receptors or other proteins involved in signal transduction. Conclusion: With the exception of the kit ligand and the c-kit proto-oncogene, which have been demonstrated to play a role in the survival of the primordial germ cell in the testis during embryogenesis, little is known of the direct role of the other growth factors in spermatogenesis. It is likely that in the near future that the function of many of these proteins in the regulation of spermatogenesis will be identified. Eventually, this information will be used to develop specific therapies and diagnostic procedures for the infertile male.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00182039
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  • 6
    Electronic Resource
    Electronic Resource
    Infrared Spectroscopy of Comet Hale-Bopp (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 71-80 
    Details
    ISSN: 1573-0794
    Keywords: Infrared ; spectroscopy ; composition ; comets
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract High resolution (λ/δλ ∼ 20,000) spectra of comet C/1995 O1 (Hale-Bopp) in the 2–5 μm region were obtained during UT 2–5 March 1997 using CSHELL at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea. The heliocentric and geocentric distances of the comet were ∼1.1 AU and ∼1.5 AU,respectively. We detected emission lines of the gas-phase molecules H2O, 4, C2H6, C2H2, HCN, and CO and derived absolute production rates and relative abundances for all species. We also used the 2-dimensional nature of the CSHELL data to investigate the spatial distribution of the molecules and find evidence that CO was derived at least partly from an extended source in the coma.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006227530238
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  • 7
    Electronic Resource
    Electronic Resource
    Ion mixing and thermochemical properties of markers in Cu (1986)
    Springer
    Applied physics 41 (1986), S. 171-174 
    Details
    ISSN: 1432-0630
    Keywords: 61.80 ; 66.30
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Markers of Nb, Ru, Ag, In, Sb, Hf, Pt, Au, and Bi in Cu were mixed by irradiation with 750 keV Kr at 77 K and analyzed in situ by backscattering of 1.9 MeV He+. Cu with Pt and Au markers were also irradiated and analyzed at 7 K. The results were identical to those obtained at 77 K results. The measured mixing efficienciesDt/øF D , for the various markers correlate with their respective impurity tracer diffusivities and impurity-vacancy binding energies in Cu. The correlation suggests that diffusion by a vacancy mechanism during a thermal spike as an important process in ion mixing of marker atoms in Cu.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00616835
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  • 8
    Electronic Resource
    Electronic Resource
    Efficient production of intact human parathyroid hormone in a Saccharomyces cerevisiae mutant deficient in yeast aspartic protease 3 (YAP3) (1998)
    Springer
    Applied microbiology and biotechnology 50 (1998), S. 187-192 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract When human parathyroid hormone (hPTH) is expressed as a secretory product in yeast, the main problem is the aberrant proteolytic cleavage that reduces the yield of intact protein. To overcome this problem, we developed an hPTH expression system using a host strain in which the YAP3 gene encoding yeast aspartic protease 3 (YAP3) was disrupted. After 48 h of culture, most of the hPTH secreted by the yap3 disruptant remained intact, whereas more than 90% of the hPTH secreted by the wild-type strain was cleaved. When the authentic hPTH was incubated in each of the culture supernatants of untransformed yap3 disruptant and wild-type strain, the proteolysis proceeded much more slowly in the culture supernatant of yap3 disruptant than in that of the wild type. The extent of hPTH proteolysis was also significantly reduced by the addition of pepstatin A, a specific aspartic protease inhibitor. The results suggest that YAP3 is involved in the internal cleavage of hPTH expressed in yeast. The correct processing of the intact hPTH secreted in the yap3 disruptant demonstrates that the yeast mutant lacking the YAP3 activity is a suitable host for the high-level expression of intact hPTH.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530051275
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  • 9
    Electronic Resource
    Electronic Resource
    Use of microorganism-immobilized polyurethane foams to absorb and degrade oil on water surface (2000)
    Springer
    Applied microbiology and biotechnology 54 (2000), S. 418-423 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Highly oil-absorbent polyurethane foam (PUF) materials were obtained by polymerizing polyether polyol mixture and carbodiimide-modified d-methyl diisocyanate in a weight ratio of 10:2. The foam materials were prepared to contain inorganic nutrients (slow-release fertilizer; SRF) and oil-degrading yeast cells, Yarrowia lipolytica 180, to be applied for removal of oil films on surface waters through absorption and biodegradation after oil spills. PUFs absorbed 7–9 times their own weight of Arabian light crude oil and the oil absorbency appeared to improve as the ratio of surface area to foam weight increased. PUFs showed excellent floatability which was maintained for more than 6 months in sea water, and less than 5% of the absorbed oil was released when the foams were left on water for more than 10 days. For immobilization of yeast cells into PUFs, various immobilization techniques were tested to compare their oil degrading ability and the maintenance thereof. All immobilized cells showed oil degrading abilities as good as those of free cells immediately after the preparation of PUFs, however, the activity of chitin-immobilized cells remained at a high level for the longest period of preservation. The high efficiency of oil absorption and oil degradation by PUF-immobilized yeast cells suggested that PUF-immobilized cells have a high potential as a bioremediation technique for the treatment of oil films on surface waters.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002530000384
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  • 10
    Electronic Resource
    Electronic Resource
    MR cholangiopancreatography: comparison between half-Fourier acquisition single-shot turbo spin-echo and two-dimensional turbo spin-echo pulse sequences (1998)
    Springer
    Abdominal imaging 23 (1998), S. 398-403 
    Details
    ISSN: 1432-0509
    Keywords: Key words: Bile ducts, MR—Magnetic resonance (MR), comparative studies—Magnetic resonance (MR), half-Fourier imaging.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract. Background: To compare half-Fourier acquisition single-shot turbo spin-echo (HASTE) magnetic resonance cholangiopancreatography (MRCP) with two-dimensional turbo spin-echo (2D TSE) MRCP for imaging pancreatobiliary diseases. Methods: Twenty-seven patients with biliary or pancreatic disease underwent MRCP on a 1.0-T scanner with a body phased-array coil. A T2-weighted HASTE sequence (18 s) and a T2-weighted 2D TSE sequence (45 s) were used during a breath-hold by the patient. The source images and maximum intensity projection images of both sequences were reviewed independently by two radiologists. Results: Motion artifacts were more severely pronounced with 2D TSE sequences than with HASTE sequences (p 〈 0.001). All obstructions and their sites were accurately identified with both sequences. Filling defects (calculi) in bile ducts were identified in all 22 segments (100%) with HASTE-MRCP, whereas calculi in 19 of 22 segments (86%) were identified with 2D TSE-MRCP (p= 0.25). Three missed sites on 2D TSE-MRCP were intrahepatic bile ducts. Conclusions: HASTE-MRCP is superior to 2D TSE-MRCP in terms of detecting motion artifacts and visualization of the pancreatic ducts. HASTE-MRCP is comparable to 2D TSE-MRCP for visualization of the biliary ducts and their obstruction and is superior to 2D TSE-MRCP for identification of calculi in intrahepatic bile ducts.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002619900368
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