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"Bose, A."
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Electron uptake by iron-oxidizing phototrophic bacteria
Oxidation–reduction reactions underlie energy generation in nearly all life forms. Although most organisms use soluble oxidants and reductants, some microbes can access solid-phase materials as electron-acceptors or -donors via extracellular electron transfer. Many studies have focused on the reduction of solid-phase oxidants. Far less is known about electron uptake via microbial extracellular electron transfer, and almost nothing is known about the associated mechanisms. Here we show that the iron-oxidizing photoautotroph
Rhodopseudomonas palustris
TIE-1 accepts electrons from a poised electrode, with carbon dioxide as the sole carbon source/electron acceptor. Both electron uptake and
ruBisCo
form I expression are stimulated by light. Electron uptake also occurs in the dark, uncoupled from photosynthesis. Notably, the
pioABC
operon, which encodes a protein system essential for photoautotrophic growth by ferrous iron oxidation, influences electron uptake. These data reveal a previously unknown metabolic versatility of photoferrotrophs to use extracellular electron transfer for electron uptake.
Little is known about extracellular electron uptake by microbes. Here Bose
et al
. show that the anoxygenic photoautotroph
Rhodopseudomonas palustris
TIE-1 accepts electrons from a poised electrode, which can be uncoupled from photosynthesis, and the pioABC system has a role in this uptake.
Journal Article
Comparative study of effective photoabsorber CuO thin films prepared via different precursors using chemical spray pyrolysis for solar cell application
Copper oxide (CuO) thin film is a promising material used as a photo-absorber layer in solar cell application due to its narrow bandgap, low cost and high abundance. In this work, the CuO thin films have been prepared using various source materials such as Cu(NO3)2·3H2O, CuCl2·2H2O and Cu(CH3COO)2·H2O by chemical spray pyrolysis technique. The XRD result shows an increased crystallite size for Cu–N compared with Cu–Cl and Cu–A films. Good optical absorption in the visible region is observed for all CuO films and Cu–N film illustrates high absorption coefficient in the order of 5.7 × 105 cm−1. From SEM analysis, flake like morphology is observed for Cu–N and Cu–A films. The good electrical property i.e. high conductivity (0.0611 S cm−1) and carrier concentration (2.287 × 1017 cm−3) is observed for Cu–N films. All CuO films exhibit a single semicircle impedance nature and smaller diameter of semicircle corresponding to Cu–N film indicates low electrical resistivity present in the sample. From I–V measurement, it is observed that the high current for Cu–N (16.6 µA) than Cu–Cl (2.3 µA) and Cu–A (10.7 µA). All CuO films are photo-responsive under solar light exposure, which is due to high absorption coefficient that leads to higher photocurrent (20.5 µA) for Cu–N film. The best solar cell performance is obtained for Cu–N film which shows an efficiency of 0.31%. From the above results, we conclude that Cu–N is an optimum precursor for fabricating CuO based thin film solar cell.
Journal Article
TWISTED CONJUGACY IN LINEAR ALGEBRAIC GROUPS
Let
k
be an algebraically closed field,
G
a linear algebraic group over
k
and φ ∈ Aut(
G
), the group of all algebraic group automorphisms of
G
. Two elements
x
;
y
of
G
are said to be φ-twisted conjugate if
y
=
gx
φ(g)
–1
for some
g
∈
G
. In this paper we prove that for a connected non-solvable linear algebraic group
G
over
k
, the number of its φ-twisted conjugacy classes is infinite for every φ ∈ Aut(
G
).
Journal Article
Structural, optical, electrical and electrochemical properties of Fe:Co3O4 thin films for supercapacitor applications
Cubic structured pure and Fe-doped cobalt oxide thin film electrodes are successfully prepared by nebulizer spray pyrolysis technique. Single phase polycrystalline cubic structure with (220) plane orientation are observed in the XRD analysis for pure and Fe-doped cobalt oxide films. From the optical analysis, two bandgaps are observed in the range 1.366–1.713 eV and 2.846–2.925 eV for lower and higher energy regions respectively. HR-SEM images revealed the formation of well covered and spherical shaped particles in the formed films. The increase of electrical conductivity with Fe doping concentration has been confirmed at room temperature. The maximum specific capacitance value is observed in the 2.5 wt% of Fe doped Co
3
O
4
thin film electrode at the scan rate of 2 mV/s.
Journal Article
Tripled yield in direct-drive laser fusion through statistical modelling
Focusing laser light onto a very small target can produce the conditions for laboratory-scale nuclear fusion of hydrogen isotopes. The lack of accurate predictive models, which are essential for the design of high-performance laser-fusion experiments, is a major obstacle to achieving thermonuclear ignition. Here we report a statistical approach that was used to design and quantitatively predict the results of implosions of solid deuterium–tritium targets carried out with the 30-kilojoule OMEGA laser system, leading to tripling of the fusion yield to its highest value so far for direct-drive laser fusion. When scaled to the laser energies of the National Ignition Facility (1.9 megajoules), these targets are predicted to produce a fusion energy output of about 500 kilojoules—several times larger than the fusion yields currently achieved at that facility. This approach could guide the exploration of the vast parameter space of thermonuclear ignition conditions and enhance our understanding of laser-fusion physics.
A statistical approach to designing and predicting the fusion yield of cryogenic deuterium–tritium implosions leads to tripled yield in direct-drive laser fusion of deuterium–tritium layered targets.
Journal Article
Beach Erosion Assessment and Tourism Viability Analysis at Mandarmani Coast, West Bengal, India
Mandarmani is a popular seaside tourist destination in Coastal West Bengal, India. The geomorphologically dynamic and ecologically diverse terrain falls within an active coastal belt with strong erosion but limited accretion. It is important to monitor and predict changes in beach morphology and shoreline over a short and long timescale to identify the specific drivers of such changes and their related impacts. While manual ground surveying techniques are relatively more accurate for this purpose, Remote Sensing and GIS techniques are proven to be more applicable as they are relatively accurate, cost-effective, less time-consuming and can cover a large coastal belt. The present paper analysed the beach morphology and shoreline changes along the Digha-Mandarmani coast of West Bengal using RS & GIS as a tool and fish net model to demarcate the erosion and accretion zones, to project the future shoreline position and understand the risk of climatic hazard on the tourism establishments and their sustainability in this region in future. Such a study would help in taking informed policy choices by the planners on such growing tourism destinations developed over time, often violating the existing coastal zone regulations and thus without required environmental clearances. Should be protected with public investment to safeguard the business hub, or will be allowed to face its natural consequences?
Journal Article
A novel method for generating tricolor emission for white LED application
Copper sulphide (CuS) and tin antimonide (Sn
2
Sb
3
) are prepared by simple co-precipitation method. The prepared samples are pulverized in the ratio of 1:1 for stipulated number of rotations. X-Ray Diffractogram (XRD) is employed to analyze the structure. Both CuS and Sn
2
Sb
3
systems exhibit hexagonal crystal structure. Thermal gravimetric and differential thermal gravimetric analysis (TG-DTG) is conducted to ensure the absence of oxidation and sulphur evolution in the samples. Ultraviolet–Visible spectroscopy (UV–Vis) and Photoluminescence characterizations were carried out to study the optical properties of the compounds. The band gap obtained from the Tauc plot for CuS, Sn
2
Sb
3
and pulverized CuS:Sn
2
Sb
3
are 2.50, 3.50 and 2.80 eV where the pulverized sample shows an intermediate value between CuS and Sn
2
Sb
3
. The photoluminescence studies are carried out for all the samples and the pulverized sample CuS:Sn
2
Sb
3
showed emission over the visible region yielding better results of RGB (Red, Green, Blue) emission.
Journal Article
Morphology-dependent electrochemical energy storage property of metallic molybdenum sulfide nanosheets
The electrochemical properties of 2D nanomaterials are strongly dependent on their morphology and crystal structure. In this work, we have prepared 2D-MoS
2
nanosheets with controlled morphology through the addition of cationic, anionic, and non-ionic surfactants using the hydrothermal method. The morphology of the as-prepared samples is confirmed with SEM and TEM analysis. Galvanostatic charge storage measurements show that the hydrangea flower-like MoS
2
electrode has a high specific capacity of 304 C/g at 1 A/g current density. The fabricated symmetric supercapacitor with this electrode material gives a high energy density and power density of 37 Wh/kg and 650 W/kg, respectively, with high stability over 35,000 cycles.
Journal Article