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  • 1
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    Seawater carbonate chemistry and community calcification during Miyako Island (Japan) coral reef studies, 1994 (1995)
    PANGAEA
    In:  Supplement to: Suzuki, A; Nakamori, T; Kayanne, Hajime (1995): The mechanism of production enhancement in coral reef carbonate systems: model and empirical results. Sedimentary Geology, 99(3-4), 259-280, https://doi.org/10.1016/0037-0738(95)00048-D
    Details
    Publication Date: 2024-03-15
    Description: Coral reefs are characterized by enormous carbonate production of the organisms. It is known that rapid calcification is linked to photosynthesis under control of the carbonate equilibrium in seawater. We have established a model simulating the coexisting states of photosynthesis and calcification in order to examine the effects of photosynthesis and calcification on the carbonate system in seawater. Supposing that the rates of photosynthesis and calcification are proportional to concentrations of their inorganic carbon source, the model calculations indicate that three kinds of unique interactions of the organic and inorganic carbon productions are expected. These are photosynthetic enhancement of calcification, calcification which benefits photosynthesis and carbonate dissolution induced by respiration. The first effect appears when the photosynthetic rate is more than approximately 1.2 larger than that of calcification. This effect is caused by the increase of CO3 content and carbonate saturation degree in seawater. If photosynthesis use molecular carbon dioxide, the second effect occurs when the calcification rate is more than approximately 1.6 times larger than that of photosynthesis. Time series model experiments indicate that photosynthesis and calcification potentially enhance each other and that organic and inorganic carbon is produced more efficiently in the coexisting system than in the isolated reactions. These coexisting effects on production enhancement of photosynthesis and calcification are expected to appear not only in the internal pool of organisms but also in a reef environment which is isolated from the outer ocean during low tide. According to the measurements on the fringing type Shiraho Reef in the Ryukyu Islands, the diurnal change of water properties (pH, total alkalinity, total carbon dioxide and carbonate saturation degree) were conspicuous. This environment offers an appropriate condition for the appearance of these coexisting effects. The photosynthetic enhancement of calcification and the respiratory inducement of decalcification were observed during day-time and night-time slack-water periods, respectively. These coexisting effects, especially the photosynthetic enhancement of calcification, appear to play important roles for fluorishing coral reef communities.
    Keywords: Alkalinity, total; Alkalinity anomaly technique (Smith and Key, 1975); Aragonite saturation state; Benthos; Bicarbonate ion; Calcification/Dissolution; Calcification rate of calcium carbonate; Calcite saturation state; Calculated; Calculated using CO2SYS; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbon dioxide; Coast and continental shelf; DATE/TIME; DEPTH, water; Entire community; EPOCA; EUR-OCEANS; European network of excellence for Ocean Ecosystems Analysis; European Project on Ocean Acidification; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Measured; North Pacific; OA-ICC; OCE; Ocean Acidification International Coordination Centre; Oceanography; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Radiation, photosynthetically active; Rocky-shore community; Salinity; Suzuki_etal_94/95; Temperate; Temperature, water
    Type: Dataset
    Format: text/tab-separated-values, 189 data points
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    DATA PANGAEA
  • 2
    Electronic Resource
    Electronic Resource
    Regioselectivity of addition of thiols and amines to conjugated allenic ketones and esters (1987)
    s.l. : American Chemical Society
    The @journal of organic chemistry 52 (1987), S. 3789-3793 
    Details
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jo00226a012
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  • 3
    Electronic Resource
    Electronic Resource
    Surface cleaning of C-doped p+ GaAs with hydrogen electron cyclotron resonance plasma (1993)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 73 (1993), S. 8146-8150 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report surface cleaning of C-doped p+-GaAs epilayers with hydrogen electron cyclotron resonance plasma. Native oxides on the surface of the p+-GaAs layer can be removed at a very low substrate temperature of 150 °C. In addition, carrier concentrations decrease after cleaning at about 300 °C, which is attributed to the hydrogenation of carbon acceptors caused by hydrogen plasma exposure. A cleaning temperature of about 400 °C, a cleaning time of about 5 min, and microwave power of about 30 W appear to be optimum for the regrowth process.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.353454
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  • 4
    Electronic Resource
    Electronic Resource
    Investigation of diethylarsine as a replacement for arsine in organometallic vapor-phase epitaxy of GaAs (1990)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 3750-3752 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Epitaxial growth of GaAs has been performed with diethylarsine (DEAs) to investigate its potential as a replacement of arsine. Triethylgallium (TEG) and trimethylgallium (TMG) were used as group-III sources and carbon incorporation into the epilayers was compared. The growths were carried out under low-pressure conditions (130 Pa–1.3 kPa) to avoid a gas-phase reaction between the precursors. All epilayers exhibited p-type conductivity, and the main acceptor impurity was carbon. The lowest hole concentrations were ∼1016 and ∼1017 cm−3 for TEG and TMG, respectively. The dependence of hole concentration on V/III ratio suggests that the carbon incorporation comes mainly from TMG and DEAs for the TMG/DEAs mixture, and from DEAs for the TEG/DEAs mixture. These results indicated that the contribution of the H atom from the As—H bond in DEAs on reduction of carbon incorporation was not enough to grow high-purity GaAs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.346292
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  • 5
    Electronic Resource
    Electronic Resource
    Improvement of magneto-optical characteristics of TbFeCo/Al bilayered films at a short wavelength of 400 nm : The 5th Joint MMM−Intermag Conference (1991)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 70 (1991), S. 6395-6397 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Bilayered films composed of amorphous TbFeCo alloy and Al layers were deposited successively on glass slide substrates without plasma exposure using the facing targets sputtering system. The specimen films with the magneto-optical (MO) layer thickness tMO of 14 nm have a Kerr rotation angle θK and figure of merit fM as large as about 0.36° and 0.25, respectively, at the wavelength λ as short as about 400 nm. These values of θK and fM are considerably larger than those of the bilayered films with larger tMO in the conventional MO media. Normally, the bilayered films with tMO above 50 nm have θK of about 0.25° and fM below 0.2 at λ of 400 nm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.349954
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  • 6
    Electronic Resource
    Electronic Resource
    Dependence on channel potential structures of I–V characteristics in InAlAs/InGaAs pseudomorphic high electron mobility transistors (1997)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 81 (1997), S. 1552-1565 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have systematically examined the relationship between channel potential structures and dc device performances in the InP-based pseudomorphic high electron mobility transistors, in order to obtain a guideline for improving the channel potential structures. Based on the self-consistent calculation of the quantum states in the channel, we have designed and fabricated several pseudomorphic devices with different channel potential structures where the quantum states were systematically changed. By comparing the I–V characteristics in terms of the transconductance, the drain conductance, and the shape of the I–V curve, we have successfully extracted information on the states of channel electrons under actual device operation. Not only the design for the ground state but also that for the excited states has been shown to be important for improving the transconductance. The drain conductance was shown to improve by reducing the total channel thickness, probably due to the enhanced recombination of electrons and holes. One of the channel designs, 20 Å In0.53Ga0.47As/30 Å InAs/70 Å In0.7Ga0.3As, was shown to yield a high transconductance of 1240 mS/mm and a low drain conductance of 40 mS/mm simultaneously, for a 0.7 μm gate length device. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.363891
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  • 7
    Electronic Resource
    Electronic Resource
    Control of Zn diffusion in InP/InGaAs heterojunction bipolar transistor structures grown by metalorganic vapor phase epitaxy (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 4017-4023 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: It is known that high n+ doping in the cap layers of heterojunction bipolar transistor structures induces anomalous Zn diffusion in the base region during metalorganic vapor phase epitaxial growth. This phenomenon has been explained in terms of nonequilibrium group III interstitials generated in the n+ cap layer, which create highly diffusive Zn interstitials via the kick-out mechanism. In this article, we show that low-temperature growth (550 °C) is effective in alleviating the influence of the n+ cap layer. Due to a large time constant for the recovery of thermal point-defect equilibrium, the last-to-grow n+ cap layer cannot inject the excessive group III interstitials into the base region within a growth sequence. Under the low-temperature growth, however, the first-to-grow n+ subcollector produces group III interstitials during the whole growth sequence and thereby causes anomalous Zn diffusion. To prevent this effect, we propose interrupting the growth for a long time period (30 min) before growing the base layer, and growing the n+ subcollector at a higher temperature (600 °C). These growth techniques are shown to be effective in purging the subcollector of the undesirable group III interstitials before base-layer formation. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.361830
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  • 8
    Electronic Resource
    Electronic Resource
    Carbon doping in AlGaAs for AlGaAs/GaAs graded-base heterojunction bipolar transistor by flow-rate modulation epitaxy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2770-2772 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: This letter investigates carbon doping in AlGaAs using flow-rate modulation epitaxy (FME). The tendency of hole concentration increasing with Al composition is explained by the thermal decomposition of trimethylaluminum molecules on the substrate surface. The highest hole concentration obtained is 3×1020 cm−3 in Al0.4Ga0.6As layers. An AlGaAs/GaAs heterojunction bipolar transistor with an FME-grown compositionally graded carbon-doped base layer was fabricated for the first time. It exhibits a current gain of 25 with 2×1019 cm−3 base doping.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104781
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  • 9
    Electronic Resource
    Electronic Resource
    Minority electron lifetimes in heavily doped p-type GaAs grown by molecular beam epitaxy (1991)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 58 (1991), S. 2936-2938 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Minority electron lifetimes in molecular beam epitaxy grown Be-doped p-type GaAs are characterized systematically. Samples grown at temperatures from 550 to 700 °C have hole concentrations from 1017 to 1020 cm−3. Although electron lifetime in samples grown at temperatures higher than 650 °C remains nearly constant for each free-carrier concentration, it decreases significantly at lower growth temperatures. These tendencies are observed in common for various hole concentrations. These results can be explained in terms of an increase in nonradiative recombination centers incorporated during growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.104727
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  • 10
    Electronic Resource
    Electronic Resource
    AlGaAs/GaAs heterojunction bipolar transistors with heavily C-doped base layers grown by flow-rate modulation epitaxy (1989)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 54 (1989), S. 39-41 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: AlGaAs/GaAs heterojunction bipolar transistors are fabricated using carbon-doped p-type GaAs base regions grown for the first time by flow-rate modulation epitaxy. Because of the much smaller diffusion coefficient of carbon atoms in GaAs than that of beryllium and other p-type impurities, sharp impurity profiles are achieved. The heterojunction bipolar transistors exhibited high current gains up to 40 for a base layer width of 150 nm and base doping of 2.4×1019 cm−3 . The electron lifetime in heavily carbon-doped GaAs layers is considerably long, indicating favorable quality of heavily carbon-doped layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.100827
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