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1Author    Mariusz Máckowiak, Costas DimitropoulosRequires cookie*
 Title    Calculation of NQR v's and T l s being proportional to T 4 and T 5 , respectively  
 Abstract    The second-order Raman phonon process for a multilevel spin system is shown to give a quadru-polar spin-lattice relaxation rate T x ~ varying as T 5 at very low temperatures. This relaxation rate for quadrupole spins is similar to the one discussed for a paramagnetic spin system having a multilevel ground state. The temperature dependence of Tj is discussed on the basis of some simplifying assumptions about the nature of the lattice vibrations in the Debye approximation. This type of relaxation process has been observed below 20 K in tetramethylammonium hydrogen bis-trichloroacetate for the 35 C1 Ti _1 . Below 20 K the NQR frequency in the same crystal reveals a T 4 temperature dependence due to the induced modulations of the vibrational and librational coordinates by the low-frequency acoustic phonons. 
  Reference    Z. Naturforsch. 45a, 536—540 (1990); received August 22 1989 in revised form November 24 1989 
  Published    1990 
  Keywords    Quadrupole relaxation, low temperature, NQR 
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 TEI-XML for    default:Reihe_A/45/ZNA-1990-45a-0536.pdf 
 Identifier    ZNA-1990-45a-0536 
 Volume    45 
2Author    T. Fujim, F. Yoshii, I. Kaetsu, Y. Inoue, K. ShibataRequires cookie*
 Title    Effect of Irradiation and Immobilization on Spinach Chloroplast Activities  
 Abstract    The effect of y-ray irradiation and immobilization by means of radiation polymerization on PS II activity (0 2 evolution) o f isolated chloroplasts from spinach was investigated. Reduction o f 0 2 evolution activity by irradiation was small at lower temperatures below — 24 °C, but the activity decreased slightly by freezing at extremely low temperature below —78 °C. So the optimum low temperature range for the treatment was observed. The immobilized chloroplast in a hydrophilic polymer matrix showed the stable duration o f 0 2 evolution activity more than 700 h at 4 °C . Thermo-stability o f chloroplast was also improved greatly by immobilization. The active center o f PS II in immobilized chloroplasts was retained even after 60 min standing at 50 °C. 
  Reference    Z. Naturforsch. 35c, 477—481 (1980); received February 12 1980 
  Published    1980 
  Keywords    Radiation Effect, Chloroplast, 0 2 Evolution, Immobilization, Radiation Polymerization, Low Temperatures 
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 TEI-XML for    default:Reihe_C/35/ZNC-1980-35c-0477.pdf 
 Identifier    ZNC-1980-35c-0477 
 Volume    35 
3Author    Fumio Yoshii, Isao Kaetsu, Akio YamadaRequires cookie*
 Title    Immobilization of Erythrocytes by Radiation Polymerization of Glass-Forming Monomers at Low Temperatures  
 Abstract    The immobilization of erythrocyte as the whole cell without hemolysis was studied. It found that erythrocyte could be treated and immobilized stably by radiation polymerization o f specific monomers having high viscous and long oxyethylene units chain such as methoxypolyethylene-glycol methacrylate (M-23G) and polyethyleneglycol dimethacrylate (14G). Irradiation dose without hemolysis was limited less than lxl05r and a comonomer system consisting o f M -23G-14G, 1:1 and small quantity o f glutaraldehyde (GA) was the optimum carrier composition. The functional properties o f the immobilized erythrocyte was also investigated. It was found that the immobilized cell could be carried out carbon monoxide-oxygen gas exchange effectively and reversibly so as in the intact cell. The immobilized erythrocyte also showed the catalase activity just as in the intact cell. The stability o f erythrocyte increased greatly by the immobilization for standing at low and room temperatures and hardly hemolyzed in non-isotonic medium such as pure water. It was observed in scanning electron microscope that the immobilized erythrocyte had a hollow disk shape same as in intact cell and covered with a thin polymer layer. 
  Reference    Z. Naturforsch. 36c, 1062—1067 (1981); received June 2 1981 
  Published    1981 
  Keywords    Erythrocyte, Radiation Polymerization, Immobilization, Glass-Forming Monomer, Low Temperature, 0 2-Uptake 
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 TEI-XML for    default:Reihe_C/36/ZNC-1981-36c-1062.pdf 
 Identifier    ZNC-1981-36c-1062 
 Volume    36 
4Author    Juliane Peters, M. Soledad, Jim Énez, Domingo MoralesRequires cookie*
 Title    Effect of Extreme Temperature on Quantum Yield of Fluorescence and Membrane Leakage of the Canarian Endemic Pine (Pinus canariensis)  
 Abstract    The effect of extreme temperature on the quantum yield of fluorescence and membrane leakage of Pinus canariensis growing in 5 stands at different altitudes and orientation in Tenerife (Canary Islands, Spain) was determined. Needles were collected from the field and transferred to the laboratory where they were kept in a closed chamber with water-saturated air overnight. Then they were exposed for 30 minutes in plastic bags in a water bath at temperature treatments with steps of 2K between 56 °C and -2 4 °C and the effect was deter­ mined immediately and 24 hours after the treatment by chlorophyll fluorescence and electro­ lyte leakage. Needles presented incipient damage at temperatures ranging from -5 to -1 0 °C depending on the altitude and orientation of the stand. The results were more evident when the mea­ surements were done 24 hours after the cold treatment and values were consistent with the electrolyte leakage results. Different resistance to high temperature depending on the alti­ tude and orientation was also found, varying the temperature for incipient damage from 42 to 44 °C detected with the fluorescence parameters but not with the leakage of electrolytes which was not found until 50 °C. The amplitude of thermal limits for photosynthetic effi­ ciency alteration in needles of P. canariensis was relatively narrow and similar to that of evergreen Canarian laurel forest trees. 
  Reference    Z. Naturforsch. 54c, 681—6 (1999); received December 10 1998/February 20 1999 
  Published    1999 
  Keywords    Pinus canariensis, Low Temperature, High Temperature, Altitudinal Gradient, Chlorophyll Fluorescence, Electrolyte Leakage 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0681.pdf 
 Identifier    ZNC-1999-54c-0681 
 Volume    54