PHOTOELECTRIC EFFECTS IN DYE-SENSITIZED ARTIFICIAL LIPID MEMBRANES

Using dyes of known redox potentials the specific mechanisms of dark and light potential generation is analyzed in pigmented lipid membranes. The role of the ionic and electronic conductance, as well as the redox potential gradient is specifically related to the observed open circuit voltage developed across the membrane. The results can be most easily explained by the redox electrode model.     

Torification and factorization of birational maps

Building on work of the fourth author and Morelli's work, we prove the weak factorization conjecture for birational maps in characteristic zero: a birational map between complete nonsingular varieties over an algebraically closed field of characteristic zero is a composite of blowings up and blowings down with nonsingular centers.

     

Biostimulation of HeLa cells by low-intensity visible light

Summary The action spectra of low-intensity light in the range from 300 to 900 nm on the synthesis rate of nucleic acids in the culture of HeLa cells has been measured. The synthesis of DNA and RNA is stimulated in several spectral intervals with maxima nearby 400, 630, 680, 760 and 820 nm. The stimulation effect is very sensitive to the irradiation duration (light intensity) at a fixed dose. The dose that causes the maximal stimulation is approximately 10 times smaller in the near-UV blue region than in red-IR region.

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Riassunto Si è misurato lo spettro d’azione della luce a bassa intensità nell’intervallo da 300 a 900 nm sul tasso di sintesi degli acidi nucleici in culture di cellule HeLa. La sintesi di DNA ed RNA è stimolata in parecchi intervalli spetrali con massimi vicino a 400, 630, 680, 760 e 820 nm. L’effetto di stimolazione è molto sensibile alla durata d’irradiazione (intensità della luce) ad una dose fissa. La dose che causa la stimolazione massima è approssimativamente dieci volte piú piccola nella regione blu dell’ultravioletto vicino che nella regione del rosso-infrarosso.

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Резюме Измерен спектр действия низкоинтенсивного света в диапазоне (300⋎900) нм на скорость синтеза нуклеиновых кислот в культуре клеток HeLa 1.5 часа после облучения. Синтез ДНК и РНК стимулируется в несколбких спектральных интервалах с максимумами вблизи 400, 630, 680, 760 и 820 нм. Эффект стимуляции очень чувствителен к продолжительности облуения (интенсивности света) при фиксированной дозе. Доза, при которой наблюдается максимальная стимудяция, в несколько ваз меньше в ближнеи УФ-синей области с максимумом около 400 нм.

     

Stimulation of E. coli growth by laser and incoherent red light

Summary The effect of low-intensity He−Ne laser radiation (λ=632.8 nm) and incoherent red light on DNA synthesis and cell division in Escherichia coli has been studied. It has been shown that the radiations of He−Ne laser (λ=632.8 nm) and filament lamp (λ=(631±4) nm) stimulate DNA synthesis and cell growth at doses of 10³ to 10⁴ J/m². The highest level of DNA synthesis is observed 10 min after irradiation and the difference in the numbers of irradiated and control cells is maximum 1 or 2 h after irradiation. The action spectrum of visible light on the growth rate of E. coli cells (from 560 nm to 640 nm) has been measured. The action spectrum has its maximum at (620±7) nm.

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Riassunto Si è studiato l'effetto della radiazione laser He−Ne a bassa intensità e della luce rossa incoerente sulla sintesi del DNA e sulla divisione della cellula in Escherichia coli. Si è mostrato che le radiazioni del laser He−Ne (λ=632.8 nm) e della lampada con filamento (λ=(631±4) nm) stimolano la sintesi del DNA e la crescita cellulare a dose di (10³⋎10⁴) J/m². Il piú alto livello di sintesi del DNA è osservato 10 min dopo l'irradiazione e la differenza nei numeri di cellule irradiate e di controllo è massima 1 o 2 ore dopo irradiazione. Si è misurato lo spettro d'azione della luce visibile sul rapporto di crescita delle cellule di E. coli (da 560 nm a 640 nm). Lo spettro d'azione ha il suo massimo a (620±7) nm.

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Резюме Изучалось влияние низконтенсивного излучения He−Ne лазэра (λ=632.8 нм) и некогерентного красного света на синтез ДНК и клеточное деление в клэтках Escherichia coli. Показано, что как излучение He−Ne лазера, так и лампьи накаливания (λ=(631±4) нм) стимулирует синтез ДНК и клетпчное леление в дозах (10⁻²⋎10⁻³) Джм². Наиболее вьисокий уровень синтеза ДНК наблюлаеттся чурез 10 минут после облучения, скорость клеточногхого делэния максимальна через (1⋎2) часа после облучения. Измерен спектр действия видимого света на скрость деления клеток E. coli от λ=560 нм до λ=640 нм. Спектр действия имеет максимум при (620±7) нм.

     

HYDROGEN GENERATION FROM ARTIFICIAL SEA HATER IN A SEMICONDUCTOR SEPTUM ELECTROCHEMICAL PHOTOVOLTAIC CELL

Visible light of the solar spectrum is directly converted to stored chemical energy of hydrogen from artificial sea water in a novel electrochemical photovoltaic cell. The principal element of the cell, modeled after the photosynthetic thylakoid membrane, is a semiconductor septum made of polycrystalline n-CdSe thin film deposited on nickel foil, which separates two aqueous solutions. Under short-circuit conditions, vigorous hydrogen evolution was seen at the Ni surface and continued as long as the cell was operated. The novel cell, the concept of which was derived from pigmented bilayer lipid membrane studies, is easy to construct, simple to operate, and appears to be a practical approach to the photochemical conversion and storage of solar energy.     

STIMULATION OF Escherichia coli DIVISION BY LOW-INTENSITY MONOCHROMATIC VISIBLE LIGHT

Abstract— Bacterial suspensions in a phosphate buffer were irradiated at 364, 404, 434, 454, 484, 520, 560. 570, 599, 619, 630, 633, 640, 693, 730 and 750 nm, incubated in Hottinguer broth, and assayed for viability by the standard surface plating technique. When irradiated at 404, 454, 560, 619, and 750 nm, the cells started dividing more rapidly, the growth stimulation effect reaching170–180% 60 min after irradiation. The shape of the action spectrum and the reduced-minus-oxidized difference spectrum of the bacterial suspensions suggest that respiratory chain components of the bacterium such as dehydrogenases and cyt d might be the photoacceptors involved. The growth stimulation effect is believed to be due to the ability of the irradiation-activated respiratory chain to produce the necessary pH gradient more rapidly, thus enabling the cells to start dividing earlier.     

Calculating the Maximum Density of the Surface Packing of Ions in Ionic Liquids

Russian Journal of Physical Chemistry A - The maximum density of monolayer packing on a graphene surface is calculated by means of molecular dynamics (MD) for ions of characteristic size and...     

Vector bundles on toric varieties

Following Sam Payne?s work, we study the existence problem of nontrivial vector bundles on toric varieties. The first result we prove is that every complete fan admits a nontrivial conewise linear multivalued function. Such functions could potentially be the Chern classes of toric vector bundles. Then we use the results of Cortiñas, Haesemeyer, Walker and Weibel to show that the (non-equivariant) Grothendieck group of the toric 3-fold studied by Payne is large, so the variety has a nontrivial vector bundle. Using the same computation, we show that every toric 3-fold X either has a nontrivial line bundle, or there is a finite surjective toric morphism from Y to X, such that Y has a large Grothendieck group.