Uncertainties in Electric Circuit Analysis of Anisotropic Electrical Conductivity and Piezoresistivity of Carbon Nanotube Nanocomposites.

Electrical conductivity and piezoresistivity of carbon nanotube (CNT) nanocomposites are analyzed by nodal analysis for aligned and random CNT networks dependent on the intrinsic CNT conductivity and tunneling barrier values. In the literature, these parameters are assigned with significant uncertainty; often, the intrinsic resistivity is neglected. We analyze the variability of homogenized conductivity, its sensitivity to deformation, and the validity of the assumption of zero intrinsic resistivity.

Singlet-triplet fission of carotenoid excitation in light-harvesting LH2 complexes of purple phototrophic bacteria.

The current generally accepted structure of light-harvesting LH2 complexes from purple phototrophic bacteria conflicts with the observation of singlet-triplet carotenoid excitation fission in these complexes. In LH2 complexes from the purple bacterium Allochromatium minutissimum, a drop in the efficiency of carotenoid triplet generation is demonstrated, which correlates with the extent of selective photooxidation of bacteriochlorophylls absorbing at ~850 nm. We conclude that singlet-triplet fission of carotenoid excitation proceeds with participation of these excitonically coupled bacteriochlorophylls.

[Triplet state of the primary donor in reaction centers of the phototrophic bacterium Rhodobacter sphaeroides R26 with active photoinduced electron transfer].

EPR characteristics of transient paramagnetic states photoinduced in isolated reaction centers of Rhodobacter sphaeroides R26 with intact electron transfer have been studied. It was demonstrated that the detected weak triplet state EPR signal belongs to the primary donor molecule and is populated via the conventional mechanism of radical pair S-T0 mixing. The distortion of the spectral shape of this signal is explained by the triplet quantum yield anisotropy brought about by the short lifetime of precursor radical pairs.

[Effect of secondary prophylaxis on quality of life in gerontologic patients at the rehabilitation center for the disabled Patriotic war veterans in local sanatorium].

Aim: To study efficacy of sanatorium treatment of aged patients with gastroenterological and locomotor diseases in the heriatric center.

Material And Methods: 100 patients were investigated for effects of sanatorium treatment on quality of life.

Results: Clinical symptoms depended on the patients' age.

[Role of singlet-excited and triplet states in chlorophyll photooxidation].

Effect of p-benzoquinone concentration [Q] on the yield of ion-radicals during photooxidation of chlorophyll a with p-benzoquinone was studied by the method of impulse photoconductivity. It has been shown that in the studied range [Q] = 10(-6)--10(-1) M the relationship delta n ([Q]) has a bell-like shape with the maximum at [Q] approximately 10(-3) M. From the relationship obtained the ratio beta = delta ns/delta nt of the contributions of singlet--excited (Chl) and triplet (Chl) states of the pigment into the total yield of ion-radicals is evaluated: for [Q] less than or equal to 10(-1) M beta less than or approximately 10(-3).

[Impulse photoconductance of solutions of chlorophyll and its analogs. IV. Absolute quantum yield of ion radical formation during photooxidation of chlorophyll a by n-benzoquinone].

The values of absolute quantum yield phi of the formation of free ion-radicals during the illumination of alkohol solutions of chlorophyll alpha (Chl) and rho-benzoquinone (Q) at room temperature were obtained by the method of impulse photoconductance. With an increase of the dielectric constant epsilon of the solvent from approximately 6 to approximately 25 phi increases by two orders ( approximately 10(-3)--approximately 10(-1). That obtained relationship phi (epsilon) is explained by epsilon effect on the efficiency of dissociation of "solvent-shared" ion-radical pair Chls+.

[Impulse photoconductivity of solutions of ohlorophyll and its analogs. III. Photoconductivity of hexanol solutions of chlorophyll a in the presence of n-benzoquinone. Kinetic and temperature measurements].

It is shown that an increase deltasigma of electroconductivity of chlorophyll "a" (Chlalpha) solution in hexanole in the presence of n-benzoquinone (Q) under impulse illumination of solution is proportional to flash intensity: deltasigma=1(0,99+/-0,07). Dependence deltasigma on solution temperature is of an exponential character with the activation energy Esigma=0,30+/-0,01 ev. In the temperature range studied (248--298 degrees K) the ratio between the recombination velocity constant and the mobility of ion-radicals Chlalpha+ and Q-(Kp/mu) is shown to be equal (8+/-1)X 10(-8) cm-v.

[Impulse photoconductivity of solutions of chlorophyll and its analogs. II. Effect of medium polarity on the yield of ion-radicals during the photoxidation of chlorophyll a ].

The effect of the dielectric constant epsilon of the solvent on the yield delta n of ion-radicals during photooxidation of chlorophy-l a with n-benzoquinone was studied by the method of impulse photoconductivity. It was shown that in the studied range of dielectric constant valve (epsilon congruent to 5-25) delta n monotonously increased with an increase of epsilon the relationship delta n (epsilon) being of clearly pronounced S-like character with a bend in the region of epsilon congruent to 10. A half-quantitative explanation of the data obtained is presented.