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PubMed2003

A preliminary investigation into light-modulated replication of nanobacteria and heart disease.

OBJECTIVE: The purpose of this preliminary study is to evaluate the effect of various wavelengths of light on nanobacteria (NB). BACKGROUND DATA: NB and mitochondria use light for biological processes. NB have been described as multifunctional primordial nanovesicles with the potential to utilize solar energy for replication. NB produce slime, a process common to living bacteria. Slime release is an evolutionary important stress-dependent phenomenon increasing the survival chance of individual bacteria in a colony. In the cardiovascular system, stress-induced bacterial colony formation may lead to a deposition of plaque. METHODS: Cultured NB were irradiated with NASA-LEDs at different wavelengths of light: 670, 728 and 880 nm. Light intensities were about 500k Wm(-2), and energy density was 1 x 10(4) J m(-2). RESULTS: Monochromatic light clearly affected replication of NB. Maximum replication was achieved at 670 nm. CONCLUSIONS: The results indicate that suitable wavelengths of light could be instrumental in elevating the vitality level of NB, preventing the production of NB-mediated slime, and simultaneously increasing the vitality level of mitochondria. The finding could stimulate the design of cooperative therapy concepts that could reduce death caused by myocardial infarcts.

Bacteria↗
PubMed2002

Sub-micromorphology of the epicuticle of hornets: AFM studies.

The upper part of the hornet cuticle in the abdominal region reveals several structures. First, situated at intervals of 10 microm or more apart, there are depressions housing a peripheral photoreceptor (PP) and between every two of these, there are horizontal flats resembling an irregular polygon which are mostly elongated and about 100 microm2 in area. Upon each such terrace-like flat there are tile-shaped protuberances up to several micrometres in length and mostly running parallel to one another, covering the entire surface. Between every two such terraces there is a 'step' of up to 1.4 microm in height. Both the 'tiles' and 'steps' terminate in front of the distal part of each PP, which is a recessed and smooth region. Secondly, in other regions of the cuticle one can note other surface configurations such as: (a) a paucity of 'tiles'; (b) no 'tiles' at all but a chessboard-like pattern, the 'squares' of which contain rectangles recessed to various depths, interspersed among 'plaques' that are not recessed and may even protrude; and (c) anfractuous (characterized by windings and turnings) flats that are intermittently criss-crossed by grooves. In addition to the above, most of the cuticle also displays numerous setae (i.e. small hairs). We suppose that all the described structures and configurations either contribute to enlargement of the cuticular surface, or act as an optical grid, thereby enhancing the absorption of light. We further speculate that for hornets in flight, situations may arise where part of the above mentioned structures orientates perpendicular to the sunlight and this entire orientation acts to direct the solar energy toward and into the PP so as to enable greater utilization of light as an energy source.

Abdomen↗
PubMed1995

Radon entry control in new house construction.

People exposed to high concentration levels of radon face an increased risk of developing lung cancer. The risk is directly proportional to the length and level of radon exposure. Because of health reasons, it is safer to build new houses with radon mitigation systems installed in slab-on-grade houses. However, the interrelationships between parameters and factors governing radon entry and control are highly complex. A study performed by the University of Florida has examined the effectiveness of different radon entry control approaches. The analysis was based on 47 houses from three research projects conducted by the University of Florida (14 houses), Florida Solar Energy Center (13 houses), and GEOMET Technologies (20 houses). The evaluation of the performance and effectiveness of improved floor slabs, space conditioning, and ventilating systems were analyzed. Statistical analyses of the interrelationship between various parameters were also performed. Study findings such as the important factors in reducing radon entry and the effectiveness of passive construction approach and active subslab depressurization systems are presented in this paper.

Air Conditioning↗
PubMed2003

Diluted II-VI oxide semiconductors with multiple band gaps.

We report the realization of a new mult-band-gap semiconductor. Zn(1-y)Mn(y)OxTe1-x alloys have been synthesized using the combination of oxygen ion implantation and pulsed laser melting. Incorporation of small quantities of isovalent oxygen leads to the formation of a narrow, oxygen-derived band of extended states located within the band gap of the Zn(1-y)Mn(y)Te host. When only 1.3% of Te atoms are replaced with oxygen in a Zn0.88Mn0.12Te crystal the resulting band structure consists of two direct band gaps with interband transitions at approximately 1.77 and 2.7 eV. This remarkable modification of the band structure is well described by the band anticrossing model. With multiple band gaps that fall within the solar energy spectrum, Zn(1-y)Mn(y)OxTe1-x is a material perfectly satisfying the conditions for single-junction photovoltaics with the potential for power conversion efficiencies surpassing 50%.

Journal Article↗
PubMed2004

New precision measurement of the 3He(4He,gamma) 7Be cross section.

The 3He(4He,gamma) 7Be reaction plays an important role in determining the high energy solar neutrino flux and in understanding the abundances of primordial 7Li. This Letter reports a new precision measurement of the cross sections of this direct capture reaction, determined by measuring the ensuing 7Be activity in the region of Ec.m.=420 to 950 keV. Various recent theoretical fits to our data result in a consistent extrapolated value of S34(0)=0.53(2)(1) keV b.

Journal Article↗
PubMed2006

On the logical relationship between natural selection and self-organization.

Most evolutionary biologists cherish Darwin's theory of natural selection (NS) as the process of adaptive evolution more than 140 years after publication of his first book on the subject. However, in the past few decades the study of self-organization (SO) in complex dynamical systems has suggested that adaptation may occur through intrinsic reorganization without NS. In this study, we attempt to describe the logical framework that relates the general process of SO to the specific process of NS. We describe NS as a mechanism that coordinates the coevolution of species in an ecosystem to effectively capture, process and dissipate solar energy into the earth's shadow. Finally, we conclude that NS is an emergent process founded on the same thermodynamic imperatives that are thought to underlie all SO. This perspective suggests that the theory of self-organizing systems offers a broader physical context in which to understand the process of NS, rather than contesting it. It even suggests the possibility that there may be a physical basis for understanding the origin of the process of NS. Rather than being merely a fluke of nature, the origin of NS that may be driven by energy flows across gradients.

Adaptation, Biological↗
PubMed1979

Cultivable mycobacteria in sphagnum vegetation of moors in South Sweden and coastal Norway.

Intact sphagnum vegetation from moors in south Sweden and coastal areas of west Norway contained cultivable mycobacteria in 32% and 30% of the specimens, respectively. This frequency of specimens is lower than the 50% previously found in the partly altered moors of northwestern Germany, but the Scandinavian moors contained a larger variety of species. On both intact and altered moors M. chelonei and M. sphagni sp. nov. were found, the latter a homologous group of 151 strains. In south Sweden the highest frequency was found in S. balticum, S. recurvum. S. tenellum and S. compactum & molle. (40-65%). In coastal Norway the highest frequency was found in S. rubellum (48%) which offers favourable conditions for the accumulation of solar energy due to the red brown colour in the upper parts. Combined with a high humidity in coastal Norway in summer, this may contribute to the growth of mesophilic mycobacteria. A significant affinity of M. chelonei to S. tenellum was stated.

Mycobacterium↗
PubMed2002

Asteroid 1950 DA's encounter with Earth in 2880: physical limits of collision probability prediction.

Integration of the orbit of asteroid (29075) 1950 DA, which is based on radar and optical measurements spanning 51 years, reveals a 20-minute interval in March 2880 when there could be a nonnegligible probability of the 1-kilometer object colliding with Earth. Trajectory knowledge remains accurate until then because of extensive astrometric data, an inclined orbit geometry that reduces in-plane perturbations, and an orbit uncertainty space modulated by gravitational resonance. The approach distance uncertainty in 2880 is determined primarily by uncertainty in the accelerations arising from thermal re-radiation of solar energy absorbed by the asteroid. Those accelerations depend on the spin axis, composition, and surface properties of the asteroid, so that refining the collision probability may require direct inspection by a spacecraft.

Journal Article↗
PubMed2002

Antioxidants in photosynthesis and human nutrition.

The harnessing of solar energy by photosynthesis depends on a safety valve that effectively eliminates hazardous excess energy and prevents oxidative damage to the plant cells. Many of the compounds that protect plant cells also protect human cells. Improving plant resistance to stress may thus have the beneficial side effect of also improving the nutritional quality of plants in the human diet. The pathways that synthesize these compounds are becoming amenable to genetic manipulation, which may yield benefits as widespread as improved plant stress tolerance and improved human physical and mental health.

Antioxidants↗
PubMed1996

Rate Constants for Charge Transfer Across Semiconductor-Liquid Interfaces

Interfacial charge-transfer rate constants have been measured for n-type Si electrodes in contact with a series of viologen-based redox couples in methanol through analyses of the behavior of these junctions with respect to their current density versus potential and differential capacitance versus potential properties. The data allow evaluation of the maximum rate constant (and therefore the electronic coupling) for majority carriers in the solid as well as of the dependence of the rate constant on the driving force for transfer of delocalized electrons from the n-Si semiconducting electrode into the localized molecular redox species in the solution phase. The data are in good agreement with existing models of this interfacial electron transfer process and provide insight into the fundamental kinetic events underlying the use of semiconducting photoelectrodes in applications such as solar energy conversion.

Journal Article↗
PubMed1983

Role of Light Intensity and Temperature in the Regulation of Hydrogen Photoproduction by the Marine Cyanobacterium Oscillatoria sp. Strain Miami BG7.

The effects of several key environmental factors on the development and control of hydrogen production in the marine blue-green alga (cyanobacterium) Oscillatoria sp. strain Miami BG7 were studied in relation to the potential application of this strain to a bio-solar energy technology. The production of cellular biomass capable of evolving hydrogen gas was strongly affected by light intensity, temperature, and the input of ammonia as a nutrient. Depletion of combined nitrogen from the growth media was a prerequisite for the initiation of hydrogen production. Maximum hydrogen-producing capability coincided with the end of the linear phase of growth. Hydrogen production exhibited considerable flexibility to environmental extremes. The rate of production saturated at low light intensities (i.e., 15 to 30 muEinsteins/m per s), and no photoinhibition was observed at high light intensity (i.e., 1,000 muEinsteins/m per s). The upper temperature limit for production was 46 degrees C. Above the light compensation point for O(2) evolution H(2) production was inhibited. However, this problem was alleviated by two related phenomena. (i) The capacity of cells to evolve oxygen deteriorated with increasing culture age and nitrogen depletion, and (ii) the ability of these cells to produce oxygen in closed anaerobic hydrogen production systems was temporally limited.

Journal Article↗
PubMed1999

Ethanol synthesis by genetic engineering in cyanobacteria.

Cyanobacteria are autotrophic prokaryotes which carry out oxygenic photosynthesis and accumulate glycogen as the major form of stored carbon. In this research, we introduced new genes into a cyanobacterium in order to create a novel pathway for fixed carbon utilization which results in the synthesis of ethanol. The coding sequences of pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adh) from the bacterium Zymomonas mobilis were cloned into the shuttle vector pCB4 and then used to transform the cyanobacterium Synechococcus sp. strain PCC 7942. Under control of the promoter from the rbcLS operon encoding the cyanobacterial ribulose-1, 5-bisphosphate carboxylase/oxygenase, the pdc and adh genes were expressed at high levels, as demonstrated by Western blotting and enzyme activity analyses. The transformed cyanobacterium synthesized ethanol, which diffused from the cells into the culture medium. As cyanobacteria have simple growth requirements and use light, CO2, and inorganic elements efficiently, production of ethanol by cyanobacteria is a potential system for bioconversion of solar energy and CO2 into a valuable resource.

Journal Article↗
PubMed1980

Purification and properties of the periplasmic hydrogenase from Desulfovibrio desulfuricans.

The periplasmic hydrogenase of Desulfovibrio desulfuricans was isolated and purified. Cells were washed with Tris-EDTA and the enzyme precipitated from the wash with ammonium sulfate. Absorption chromatography on DEAE and hydroxyapatite yielded the enzyme at better than 95% purity as judged by gel electrophoresis. The hydrogenase catalyzed the production of more than 9000 mumol H2/min mg protein(-1) from reduced methyl viologen at 37 degrees C. It is very stable and resists inactivation by heat (50% activity remained after 5 min in air at 65 degrees C) and by enzyme inhibitors (except N-ethylmaleimide and potassium ferricyanide). After storage in air at 4 degrees C for 1 month no activity was lost. The enzyme activity is sensitive to ionic environmental changes. With methyl viologen the optimum pH was 5.5 but with p-xylene polymeric viologen the optimum was about pH 7 but less sharp. The molecular weight was 47 X 10(3)(+/- 2 X 10(3), 52 X 10(3)(+/- X 10(3), and 56 X 19(3)(+/- 2 X 10(3) by SDS-gel electrophoresis, gel chromatography, and sedimentation equilibrium, respectively, and the isoelectric point was at pH 6.0. They enzyme might be useful in the production of hydrogen from water and solar energy.

Amino Acids↗
PubMed1997

STRUCTURE AND MEMBRANE ORGANIZATION OF PHOTOSYSTEM II IN GREEN PLANTS.

Photosystem II (PSII) is the pigment protein complex embedded in the thylakoid membrane of higher plants, algae, and cyanobacteria that uses solar energy to drive the photosynthetic water-splitting reaction. This chapter reviews the primary, secondary, tertiary, and quaternary structures of PSII as well as the function of its constituent subunits. The understanding of in vivo organization of PSII is based in part on freeze-etched and freeze-fracture images of thylakoid membranes. These images show a resolution of about 40-50 A and so provide information mainly on the localization, heterogeneity, dimensions, and shapes of membrane-embedded PSII complexes. Higher resolution of about 15-40 A has been obtained from single particle images of isolated PSII complexes of defined and differing subunit composition and from electron crystallography of 2-D crystals. Observations are discussed in terms of the oligomeric state and subunit organization of PSII and its antenna components.

Journal Article↗
PubMed2004

The application of the biosphere reserve concept to urban areas: the case of green rooftops for habitat network in Seoul.

This article consists of two parts. The first shows how the principles of the ecosystem approach can be applied to green rooftops, and the second attempts to illustrate it through a case study. In particular, it suggests new approaches and techniques for creation of green rooftops in a perspective of urban habitat network and urban biosphere reserve. To endow urban rooftops with the roles and functions of urban habitat network and urban biosphere reserve, it is necessary to apply "an ecosystem approach to urban management." In this article, an ecosystem approach to urban management is illustrated with Seoul as an example. The Habitat Network in Seoul will be reviewed with a focus on the model suggested by MAB Urban Group. Then, the roles and functions of Myeongdong UNESCO Green Rooftop and its possible contribution to building the Seoul Urban Biosphere Network will be described. The UNESCO Green Rooftop is 628 m(2) and was created on the 12th floor rooftop of UNESCO Building in Myeongdong 2-ga, Jung-ku, Seoul. In the green rooftop, which was created with goals of securing green areas and biotopes in downtown, creating an urban econetwork, securing a base for urban ecosystem study and environment education, and disseminating an idea of coexistence between nature and humankind, wetland, meadow, scrub and woodland, wall revegetation, and a vegetable field are created. Also, rainwater recycling facilities and a solar energy water circulation system were set up. Rest facilities including observation and education facilities were built. Based on the Seoul example, as well as urban biosphere reserve models suggested by the MAB Urban Group, we suggest several principles to be applied for a green rooftops to qualify as a category of urban biosphere reserves.

Architecture↗
PubMed2006

Tribute to R. G. Boutilier: skin colour and body temperature changes in basking Bokermannohyla alvarengai (Bokermann 1956).

In amphibians solar basking far from water sources is relatively uncommon since the highly permeable amphibian skin does not represent a significant barrier to the accompanying risk of losing water by evaporation. A South American frog, Bokermannohyla alvarengai (Bokermann 1956), however, spends a significant amount of the day exposed to full sun and relatively high temperatures. The means by which this frog copes with potentially high rates of evaporative water loss and high body temperatures are unknown. Thus, in this study, skin colour changes, body surface temperature, and evaporative water loss rates were examined under a mixture of field and laboratory conditions to ascertain whether changes in skin reflectivity play an important role in this animal's thermal and hydric balance. Field data demonstrated a tight correlation between the lightness of skin colour and frog temperature, with lighter frogs being captured possessing higher body temperatures. Laboratory experiments supported this relationship, revealing that frogs kept in the dark or at lower temperatures (20 degrees C) had darker skin colours, whereas frogs kept in the light or higher temperatures (30 degrees C) had skin colours of a lighter hue. Light exhibited a stronger influence on skin colour than temperature alone, suggesting that colour change is triggered by the increase in incident solar energy and in anticipation of changes in body temperature. This conclusion is corroborated by the observation that cold, darkly coloured frogs placed in the sun rapidly became lighter in colour during the initial warming up period (over the first 5 min), after which they warmed up more slowly and underwent a further, albeit slower, lightening of skin colour. Surprisingly, despite its natural disposition to bask in the sun, this species does not possess a ;waterproof' skin, since its rates of evaporative water loss were not dissimilar from many hylid species that live in arboreal or semi-aquatic environments. The natural history of B. alvarengai is largely unknown and, therefore, it is likely that the herein reported colour change and basking behaviour represent a complex interaction between thermoregulation and water balance with other ecologically relevant functions, such as crypsis.

Animals↗
PubMedDate not supplied

Light-driven hydrogen production by a hybrid complex of a [NiFe]-hydrogenase and the cyanobacterial photosystem I.

In order to generate renewable and clean fuels, increasing efforts are focused on the exploitation of photosynthetic microorganisms for the production of molecular hydrogen from water and light. In this study we engineered a 'hard-wired' protein complex consisting of a hydrogenase and photosystem I (hydrogenase-PSI complex) as a direct light-to-hydrogen conversion system. The key component was an artificial fusion protein composed of the membrane-bound [NiFe] hydrogenase from the beta-proteobacterium Ralstonia eutropha H16 and the peripheral PSI subunit PsaE of the cyanobacterium Thermosynechococcus elongatus. The resulting hydrogenase-PsaE fusion protein associated with PsaE-free PSI spontaneously, thereby forming a hydrogenase-PSI complex as confirmed by sucrose-gradient ultracentrifuge and immunoblot analysis. The hydrogenase-PSI complex displayed light-driven hydrogen production at a rate of 0.58 mumol H(2).mg chlorophyll(-1).h(-1). The complex maintained its accessibility to the native electron acceptor ferredoxin. This study provides the first example of a light-driven enzymatic reaction by an artificial complex between a redox enzyme and photosystem I and represents an important step on the way to design a photosynthetic organism that efficiently converts solar energy and water into hydrogen.

Cyanobacteria↗