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  • 1
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The acid-catalyzed hydrogen-deuterium exchange reaction in aliphatic ketones was modeled as a purely random process. Using a computer program, a statistically random hydrogen-deuterium exchange was simulated for a particular molecule, 2-indanone. For this molecule, there are two α carbons, each providing two potential sites for exchange. The program determined the relative amounts for each of the partially deuterated species, including the total percent deuteration. A comparison with mass spectral data showed good agreement with this model.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The chemical educator 3 (1998), S. 1-5 
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A very simple stepper motor controller was designed and built for a scanning monochromator. The circuit design centers around a programmable peripheral interface chip that controls the gate of four power transistors, which in turn activate the coils on the stepper motor. Besides being very inexpensive to build, the interface shows improved performance when compared to the commercially available controller.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The chemical educator 3 (1998), S. 1-9 
    ISSN: 1430-4171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An experiment which is familiar to most physical chemistry students is the speed of sound based on the Kundt’s tube.[1] The experiment also allows the student to determine the heat-capacity ratio for various gases. The process of changing gases may be more easily accomplished if the microphone in the tube can be fixed in its position relative to the speaker. In this article, this modification to the experiment is discussed in terms of resonance generated in closed pipes.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The relationship between otolith length and body length (total length) was examined in walleye pollock Theragra chalcogramma (Pallas), collected from Pacific Ocean waters adjacent to Hokkaido, Japan, and in larvae reared from fertilized eggs. A linear relationship was found between log-transformed body length and otolith length data with two inflection points at ca. 11 mm and 100 mm total length. This relationship was found to be applicable also to samples from the Japan Sea, Bering Sea and Okhotsk Sea. The early growth pattern estimated by back-calculation of otolith increments of 1-yr fish from Funka (Uchiura) Bay (Hokkaido) accorded with that obtained from size-at-age data of 0 yr fish collected in the preceding year. Differences were found in comparisons of the back-calculated early growth pattern between samples from waters adjacent to Hokkaido, the Pacific Ocean, the Japan Sea and the Okhotsk Sea. The growth curve of the Okhotsk samples was markedly different from others, showing rapid initial growth up to about 100 d after hatching and attaining a small body size in the first year.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 0942-0940
    Keywords: Cerebral vasospasm ; hypervolaemia ; natriuresis ; atrial natriuretic peptide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary To prevent symptomatic cerebral vasospasm, we have used hypervolaemia (HV) or volume expansion in patients with aneurysmal subarachnoid haemorrhage (SAH) in recent years. In these patients we could not perform effective fluid and sodium (Na) replacement because of rapid and overwhelming water and Na loss. Although this phenomenon is characteristic under hypervolaemic states, we regard it important to elucidate the mechanism underlying initiation of vasospasm after aneurysmal SAH. Patients with aneurysmal SAH, operated on within 24 hours of onset, were analysed prospectively. We selected 17 patients in good pre-operative condition. Intravascular volume expansion was accomplished with plasma fractionate or albumin and crystalloid solutions in all patients. We divided the 17 patients into two groups; symptomatic spasm group (S-group) consisting of 4 cases developing transient ischaemic symptoms and non-symptomatic spasm group (NS-group) consisting of 13 cases. In S-group, rapid and marked natriuresis developed characteristically before the onset of ischaemic symptoms. The differences in daily Na balance between the two groups were significant on the 3rd and 5th days (p 〈 0.05). The mean cumulative Na balance in S-group during the 10 days of the study (−375 ± 159 mEg) was higher than that of NS-group (−24.4 ± 225 mEq) (p 〈 0.05). Rapid natriuresis preceded the development of ischaemic symptoms, and was important as a trigger for symptomatic vasospasm after SAH. We considered that hormonal disorders were implicated in this phenomenon, and atrial natriuretic peptide (ANP), antidiuretic hormone (ADH), renin, and aldosterone were each measured three times during the period, with no significant differences, found between the two groups. It was speculated that another potent natriuretic factor, similar to ANP, induced a rapid selective natriuresis resulting in symptomatic vasospasm.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 5778-5785 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Laser-induced fluorescence (LIF) and electronic absorption spectroscopy (EAS) were used to examine pyrene adsorbed on Al2O3(112¯0) as a function of surface coverage, temperature, and adlayer order. Temperature-programmed LIF and EAS techniques were employed to measure the desorption kinetics of pyrene from Al2O3(112¯0). An activation energy of Ed=18±1 kcal/mol was obtained for pyrene desorption in the submonolayer regime assuming a first-order desorption pre-exponential of ν1=1×1013 s−1. Multilayer desorption studies revealed zero-order desorption kinetics with an activation energy of Ed =20±2 kcal/mol and a pre-exponential of ν0=3×1026±1.5 molecules/cm2 s. The formation of pyrene excimers and the structure of the pyrene adlayer were also investigated using LIF and EAS techniques. The LIF spectra for pyrene adlayers on Al2O3(112¯0) at 21 K exhibited both monomer and excimer emission. The relative amount of excimer emission at 21 K increased vs pyrene coverage from aitch-theta=0.30 monolayers (ML) to aitch-theta=4.5 ML. In addition, the excimer emission increased and the monomer emission decreased vs surface temperature between 21 and 150 K at all measured coverages. The temperature and coverage dependence of the LIF spectra suggested that excimer formation was dependent on pyrene mobility. In support of a mobility mechanism for excimer formation, LIF studies demonstrated that the excimer emission at aitch-theta=0.25 ML was quenched by xenon adsorption on the pyrene adlayer. LIF and EAS measurements also indicated that the pyrene adlayer crystallized when the adlayer was annealed above 230 K. The LIF spectra of the crystalline pyrene adlayers on the Al2O3(112¯0) surface displayed only excimer emission.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Fermentation and Bioengineering 78 (1994), S. 202 
    ISSN: 0922-338X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Fermentation and Bioengineering 72 (1991), S. 343-346 
    ISSN: 0922-338X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Fermentation and Bioengineering 70 (1990), S. 283-285 
    ISSN: 0922-338X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Fermentation and Bioengineering 71 (1991), S. 144 
    ISSN: 0922-338X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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