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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 107 (1997), S. 9354-9360 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation of p-methoxytoluene and p-methoxybenzyl alcohol at 266 nm in n-heptane solution is studied by nanosecond fluorescence and absorption spectroscopy. The formation of a p-methoxybenzyl radical is identified by its fluorescence which is induced by excitation at 308 nm. The yields of the radical are of the order of ∼10−3 for dissociation of p-methoxytoluene and p-methoxybenzyl alcohol. The growth rate of 1.5×108 s−1 for the radical is equal to the decay rate of (1.5±0.3)×108 s−1 for the precursor fluorescence in dissociation of p-methoxytoluene, whereas the growth rate of 〉1.0×109 s−1 for the radical is much faster than the decay rate of (1.8±0.3)×108 s−1 for the precursor fluorescence in dissociation of p-methoxybenzyl alcohol. The formation of the radical depends linearly on the photolysis pulse fluence for dissociation of p-methoxytoluene and p-methoxybenzyl alcohol. The data show existence of two distinct dissociation channels. p-Methoxytoluene dissociates from thermally equilibrated levels of the S1 state after vibrational relaxation, whereas p-methoxybenzyl alcohol dissociates from vibrationally excited levels of the S1 state in competition with vibrational relaxation. The difference of these channels is explained on a model of electronic coupling between the precursor and product states in the geometry where the C–H and C–O bonds are stretched in a plane perpendicular to the benzene rings. For p-methoxytoluene, the S1 state does not correlate adiabatically to the ground state of the C–H bond fission products, so intersystem crossing or internal conversion precedes dissociation. For p-methoxybenzyl alcohol, avoided crossing between the ππ* (benzene) configuration and the np(O)σ*(C–O) repulsive configuration results in the adiabatic potential-energy surface which evolves to the ground state of the C–O bond fission products allowing rapid dissociation. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 109 (1998), S. 1359-1365 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The photodissociation of diphenylmethane by excitation to the S1 state at 266 nm in n-heptane solution is studied by nanosecond fluorescence and absorption spectroscopy. The formation of the diphenylmethyl radical is identified by its fluorescence, which is induced by excitation at 308 nm, and by its absorption. The growth rate of (3.7±0.4)×107 s−1 for the radical is equal to the decay rate of (3.8±0.4)×107 s−1 for the precursor fluorescence. The quantum yield of the radical is of the order of ∼10−3. Neither dissociation to the radical nor intersystem crossing to the T1 state is thermally activated, whereas activated internal conversion to the S0 state is observed. The formation of the radical depends linearly on the photolysis pulse fluence. The data are consistent with a mechanism that the molecule undergoes intersystem crossing from thermally equilibrated levels of the S1 state to vibrationally excited levels of the T1 state at which it dissociates in competition with vibrational relaxation. The mechanism is explained in terms of electronic coupling between the precursor and product states. The S1 state does not correlate adiabatically to the ground state of the C–H bond fission products, so intersystem crossing to the T1 state precedes dissociation. In the T1 state, avoided crossing between the ππ* (benzene) configuration and the σσ* (C–H) repulsive configuration results in the adiabatic potential energy surface which evolves to the ground state of the C–H bond fission products allowing rapid dissociation. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 3432-3434 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We report on pulse laser oscillation from a p-Ge intervalence band (IVB) laser composed of a Ga-doped Ge crystal measuring about 1×1×5 mm3 which is a very small volume compared with those reported so far for shallow-acceptor-doped Ge. Laser oscillation is only achieved under uniaxial stresses greater than 1300 kg/cm2. We find that the optimum stress for lasing is around 3500–4100 kg/cm2 when the p-Ge IVB lasers are operated at liquid helium temperature. The minimum electric power needed for lasing is only 280 W at a peak period of pulse emission. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 273 (1995), S. 1055-1059 
    ISSN: 1435-1536
    Keywords: Solubilization ; micelle ; aggregational state ; light scattering ; oleic acid ; reconstitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The effect of oleic acid on the aggregational behavior of the α-sulfonated fatty acid methyl ester sodium salt (α-SFMe) and sodium linear C12/C14-alkylbenzene-sulfonate (LAS) has been studied using a light-scattering method. The solubilizing capacity of α-SFMe was larger than that of LAS, and depended both on the number of micelles in the surfactant solution and the solubilized amount per micelle. When the micellar weights for the α-SFMe and LAS systems were determined at the various oleic acid/surfactant ratios, the micellar weights initially decreased by small amounts of solubilizate and then increased with the further increase in the solubilized amounts. It was found that the solubilization process is accompanied by a reconstitution of the micelles.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1536
    Keywords: Key words Critical micellization concentration (CMC) ; solubility ; degree of counterion binding ; Krafft point ; α-sulfonatomyristic acid methyl ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  For a sodium salt of α-sulfonatomyristic acid methyl ester (14SFNa), one of the α-SFMe series surfactants, critical micellization concentration (CMC), solubility and degree of counterion binding (β) were determined by means of electrocon-ductivity measurements at different temperatures (at every 5 °C) ranging from 15 to 50 °C. The phase diagram of 14SFNa in pure water was constructed from the CMC- and solubility-temperature data, in which the Krafft temperature (critical solution temperature) was found around 0 °C. The changes in the Gibbs energy, ΔG 0 m, enthalpy, ΔH 0 m, and entropy, ΔS 0 m, upon micelle formation as a function of temperature were evaluated taking βvalues into calculation.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1435-1536
    Keywords: Key words Electroconductivity ; differential conductivity ; degree of counterion binding ; dissociation degree of micelles ; α-sulfonato-myristic acid methyl ester
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  For a sodium salt of α-sulfonatomyristic acid methyl ester (14SFNa), one of the α-SFMe series surfactants, the differential conductivity (∂κ/∂C) T , P vs. square root of concentration (√C) was employed in order to determine not only CMC but also the limiting molar conductance (Λ0) and the molar conductance of micellar species (ΛM). Based on the data of the degree of counterion binding to micelles (β) determined previously at different temperatures ranging 15–50 °C at every 5 °C, the experimental values of the degree of dissociation (ionization) of a micelle (αEX) were calculated by regarding as αEX=1−β. The ratio ΛM/Λ0 corresponding to the ratio of slopes below and above CMC in the curve of specific conductivity (κ) vs. concentration (C), which has been often assumed to be the degree of ionization of micelles (α), was compared with the present αEX. However, the ratio ΛM/Λ0 (=α) was found to have a correlationship with αEX (=1−β) as αEX≈0.40×(ΛM/Λ0), or strictly, αEX=0.40 (ΛM/Λ0)+0.08, indicating that the simple ratio of the slopes below and above CMC in κ vs. C curve is not true for αEX=1−β. On the other hand, the method proposed by Evans gave a value closer to αEX compared with the simple ratio.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1438-2199
    Keywords: Amino acids ; Cysteine metabolism ; Sulfate formation ; Taurine formation ; Hypotaurine ; Sulfur equilibrium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary l-Cysteine is mainly metabolized to sulfate and taurine through cysteinesulfinate pathway. Alternatively, sulfate is formed in rat liver mitochondria via 3-mercaptopyruvate pathway. Intraperitoneal administration of 5 mmol ofl-cysteine per kg of body weight resulted in the increase in sulfate and taurine (plus hypotaurine) excretion in the 24-h urine, which corresponded to 45.3 and 29.3%, respectively, ofl-cysteine administered. Subcutaneous injection of (aminooxy)acetate, a potent inhibitor of transaminases, together withl-cysteine halved the sulfate excretion and doubled the taurine excretion. In vitro sulfate formation froml-cysteine and froml-cysteinesulfinate in rat liver mitochondria was inhibited by (aminooxy)-acetate. The sulfate-forming activity of liver mitochondria obtained from rats injected with (aminooxy) acetate was also inhibited. These results indicate that the transamination reaction is crucial in sulfate formation and in the regulation of sulfur metabolism. Sulfur equilibrium in mammals was discussed.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 252 (1995), S. 48-52 
    ISSN: 1434-4726
    Keywords: Tegafur ; Bromodeoxyuridine ; Proliferating cell nuclear antigen ; Immunohistochemistry ; Cell mitoses
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Olfactory disturbances induced by the anticancer drug tegafur were studied in separate clinical and experimental investigations. Five patients with olfactory dysfunction after tegafur were studied and were found to have normal endoscopic findings of the olfactory cleft mucosa. The average period for drug administration was 22 months. Recovery from the olfactory disturbance was poor and biopsy of the olfactory mucosa revealed severely degenerated epithelium. In experimental studies in a guinea pig animal model, effects of oral tegafur on mitotic cells in the olfactory epithelium were examined using bromodeoxyuridine (BrdU) uptake as index. At the conclusion of 3 weeks' treatment, no pronounced morphological changes were seen, but the number of BrdU-incorporating cells decreased in proportion to the dose of tegafur used. Following long-term administration of tegafur 18 months, mitotic cells reacting to BrdU or proliferating cell nuclear antigen had virtually disappeared, indicating persistent inhibition of mitotic cell activity. Morphological changes present included decreased olfactory cell numbers, loss of cells in areas just above basal cells and degeneration of the mucous layer.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European archives of oto-rhino-laryngology and head & neck 255 (1998), S. 289-292 
    ISSN: 1434-4726
    Keywords: Key words Olfactory epithelium ; Olfactory receptor ; cells ; Cell maturation ; Proliferating cell nuclear antigen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Changes in dividing cells of the olfactory epithelium from guinea pigs of different ages were examined by immunohistochemical staining using anti-proliferating cell nuclear antigen antibody. Numerous dividing cells were scattered diffusely in the basal layer of the olfactory epithelium at 1 and 2 months following birth and then gradually decreased with maturation until 4 months. Findings then remained constant between 4 and 24 months. Subsequently, cell numbers were found to decrease as animals became older. The number of olfactory receptor cells did not vary significantly between 1 and 30 months. Although no correlation could be found between the numbers of dividing cells and olfactory receptor cells, it is still possible that the longevity of the olfactory receptor cells changes to maintain the overall size of the neuronal population.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 64 (1999), S. 144-147 
    ISSN: 1432-0827
    Keywords: Key words: Osteoporosis — Leprosy — Hypogonadism — Male.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. We measured the bone mineral density (BMD) of 353 leprosy patients (197 males 50–89 years old, average age 70.2; and 156 females 53–90 years old, average age 72.9) and serum levels of free testosterone (FT) in 81 males. The BMD of the lumbar vertebrae (L2–L4), diaphysis of the radius (1/3 radius), and the neck of the femur (neck) was measured using DXA (QDR 4500). The BMD of −2.5 SD YAM (young adult mean) in Japanese men and women was used as the cutoff value for osteoporosis in the respective genders: BMD of L2–L4, 0.751 g/cm2 (male), 0.747 g/cm2 (female); 1/3 radius, 0.655 g/cm2 (male), 0.550 g/cm2 (female); neck, 0.581 g/cm2 (female). The percentages of males with osteoporosis were 31.3% in the 50th, 32.9% in the 60th, 44.9% in the 70th, and 40.7% in the 80th decade at L2–L4. Similarly, the percentages were 33.3%, 58.3%, 74.3%, and 75.0%, respectively, at 1/3 radius. Among females, the percentages were 22.2%, 41.3%, 44.9%, and 68.8%, respectively, at L2–L4; 0%, 42.9%, 89.5%, and 78.6%, respectively, at 1/3 radius; and 11.1%, 38.6%, 67.7%, and 84.6% respectively, at neck. FT in men ranged from almost 0 to normal at each decade and BMD levels were significantly correlated with FT in all three regions of the skeleton (P 〈 0.0001). More than 30% of osteoporosis was found at each decade and FT may be one of the main factors affecting BMD in male leprosy patients.
    Type of Medium: Electronic Resource
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