Evaluating a time-delay of hydrogen production quantitatively in photosynthetic bacteria for stabilizing intermittency

Renewable energy is regarded as a clean energy source but has some problems, one of which is intermittency. To reduce this, the time-delay of hydrogen production by photosynthetic bacteria can be effective. In this study, we qualitatively evaluated the time-delay of hydrogen production by photosynthetic bacteria under various irradiation conditions, and we also quantitatively evaluated it by fitting the experimental data and the hydrogen production model with a genetic algorithm. As a result of model fitting, we found that the relationship between the lengths of the optimized time-delay of hydrogen production by photosynthetic bacteria and the amount of light irradiation is linear. And we also found that the time-delay of hydrogen production by photosynthetic bacteria had an upper limit under low light intensity. We have suggested the existence of an energy store mechanism in photosynthetic bacteria.     

Convenient green preparation of dipeptides using unprotected α-amino acids

Dipeptides and amides were obtained in high yields from N-carbobenzyloxy α-amino acids and 3-phenylpropanoic acid with unprotected α-amino acids via the corresponding mixed carbonic carboxylic anhydrides using ethyl chloroformate and triethylamine by an ecological and convenient method in which the protection of C-terminals is not needed.     

Electric conductivity of TCNQ salts of ionene polymers containing triethylenediammonium or 4,4′-bipyridilium ring

The ionene polymers were prepared by the Menshutkin reaction of α,ω-dibromoalkane (n) with triethylenediamine (TDA) or 4,4′-bipyridil (BP). Resistivities (p) and activation energies of conduction (E_a) were measured for the polymeric 7,7,8,8-tetracyanoquinodimethan (TCNQ) salts with these ionenes. The correlation between the chemical structure of the ionenes and the conductivity was discussed. In the TDA,n-TCNQ complex salts and the BP,n-TCNQ simple salts the salts of the ionenes containing even numbers of CH₂ groups showed higher conductivities than those of the ionenes containing odd numbers of CH₂ groups. The conductivities determined by the narrower interval between the N⁺ cations of the main chains were measured in the simple salts. In the complex salts the conductivities determined by the larger interval were measured. The conformational change of the matrix ionenes affected the arrangement of the TCNQ molecules. The values of p were 79.7 and 12.5 Ω cm, and the values of E_a were 0.122 and 0.063 eV for TDA,4-TCNQ complex salt and BP,5-TCNQ complex salt, respectively.     

Chronopotentiometric determination of the outer-sphere association constants of substitution-inert metal complexes

Summary A new method for the determination of association constants by the measurement of chronopotentiometric transition time has been developed and applied to the study on the outer-sphere association of some substitution-inert complex cations with sulphate ions. The association constants were determined from the change in transition time as function of the concentration of sulphate ions at ionic strength 0.1 (NaClO₄) and 25° C: 93 ±8 for [Co(NH₃)₆]³⁺SO₄ ^2–, 99 ±15 for [Co(en)₃]³⁺SO₄ ^2–, 61 ±7 for [Cr(NH₃)₆]³⁺SO₄ ^2– and 58 ±8 for [Cr(en)₃]³⁺SO₄ ^2–. The ratios of the diffusion coefficients of the univalent ion-pairs and tervalent substitution-inert complex cations were also obtained. From these ratios the diffusion coefficients of the univalent ion-pairs were calculated, which were found to differ not greatly from those of univalent complex ions with similar structures.

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Zusammenfassung Eine neue Methode zur Bestimmung von Assoziationskonstanten aus den Transitionszeiten chronopotentiometrischer Messungen wurde entwickelt. Sie wurde zur Untersuchung der Assoziation von Sulfationen in zweiter Sphäre an koordinativ abgesättigten Komplex-Kationen herangezogen. Die Assoziationskonstanten wurden aus der Abhängigkeit der Transitionszeit von der Sulfatkonzentration in Medien der Ionenstärke 0,1 (NaClO₄) und bei 25° C bestimmt. Man erhält folgende Werte: 93±8 für [Co(NH₃)₆]³⁺SO₄ ^2–, 99±15 für [Co(en)₃]³⁺SO₄ ^2–, 61±7 für [Cr(NH₃)₆]³⁺SO₄ ^2– und 58±8 für [Cr(en)₃]³⁺SO₄ ^2–. Die Verhältnisse der Diffusionskoeffizienten der einwertigen Ionenpaare zu denen der dreiwertigen Komplex-Kationen wurden ebenfalls bestimmt. Aus diesen Verhältnissen lassen sich die Diffusionskoeffizienten der Ionenpaare berechnen. Man erhält eine gute Übereinstimmung mit den Werten für einwertige Komplexionen mit ähnlicher Struktur.

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Dedicated to Prof. Dr. M. von Stackelberg on his 70th birthday.     

Synthetic macrocyclic ligands. III. Synthesis of a quinone-hydroquinone redox system incorporated with complexing ability toward cations

Two quinones bridged with a polyether chain and the corresponding hydroquinones were synthesized, and their redox reaction and complexations with sodium and potassium ions were observed.     

Relaxation behavior of laser-polarized (129)Xe gas: size dependency and wall effect of the T(1) relaxation time in glass and gelatin bulbs

Size dependency of the relaxation time T(1) was measured for laser-polarized (129)Xe gas encapsulated in different sized cavities made by glass bulbs or gelatin capsules. The use of laser-polarized gas enhances the sensitivity a great deal, making it possible to measure the longer (129)Xe relaxation time in quite a short time. The size dependency is analyzed on the basis of the kinetic theory of gases and a relationship is derived in which the relaxation rate is connected with the square inverse of the diameter of the cavity. Such an analysis provides a novel parameter which denotes the wall effect on the relaxation rate when a gas molecule collides with the surface once in a second. The relaxation time of (129)Xe gas is also dependent on the material which forms the cavity. This dependency is large and the relaxation study using polarized (129)Xe gas is expected to offer important information about the state of the matter of the cavity wall.     

Continuous dependence results for a general model of size-dependent population dynamics

We are concerned with a general model of size structured population dynamics with the growth rate depending on the individual's size and time. In this paper, we shall study the continuous dependence of the solution on all given data such as aging and birth functions, growth rate functions and initial data.