17,561 research outputs found
Some integral inequalities on time scales
In this paper, some new integral inequalities on time scales are presented by
using elementarily analytic methods in calculus of time scales.Comment: 8 page
Topological aspect of graphene physics
Topological aspects of graphene are reviewed focusing on the massless Dirac
fermions with/without magnetic field. Doubled Dirac cones of graphene are
topologically protected by the chiral symmetry. The quantum Hall effect of the
graphene is described by the Berry connection of a manybody state by the filled
Landau levels which naturally possesses non-Abelian gauge structures. A generic
principle of the topologically non trivial states as the bulk-edge
correspondence is applied for graphene with/without magnetic field and explain
some of the characteristic boundary phenomena of graphene.Comment: 12 pages, 8 figures. Proceedings for HMF-1
Optimization of β-Mannanase Production from Bacillus licheniformis TJ-101 Using Response Surface Methodology
Plackett-Burman design, central composite design and response surface analysis were carried out with the aim of optimizing culture conditions for β-mannanase production from Bacillus licheniformis TJ-101. Screening experiments of Plackett-Burman design were firstly employed to evaluate the effects of 16 variables on β-mannanase production. The four identified significant variables, i.e. the mass concentration of Na2HPO4, the mass concentration of KH2PO4, initial pH and medium volume, were further optimized by central composite design and response surface analysis. The optimum values of four critical variables were determined as Na2HPO4 6.4 g/ lL-1, KH2PO4 0.36 g L-1g/l, initial pH 7.7 and medium volume V = 30.1 mlmL. Under these conditions, the β-mannanase activity can experimentally reach a = 523.1±5.9 U/ ml mL-1 (127.7 % increase compared with the enzyme activity before optimization) at the flask level. Moreover, oxygen limitation and initial pH remarkably affected β-mannanase production from Bacillus licheniformis TJ-101 as revealed by response surface analysis. Maximum β-mannanase activity was increased by 73.7 % in a 6.6- l L fermenter using the optimized medium and dissolved oxygen at 20 % saturation
Entanglement Switch for Dipole Arrays
We propose a new entanglement switch of qubits consisting of electric
dipoles, oriented along or against an external electric field and coupled by
the electric dipole-dipole interaction. The pairwise entanglement can be tuned
and controlled by the ratio of the Rabi frequency and the dipole-dipole
coupling strength. Tuning the entanglement can be achieved for one, two and
three-dimensional arrangements of the qubits. The feasibility of building such
an entanglement switch is also discussed.Comment: 6 pages and 4 figures. To be published on Journal of Chemical Physic
The photosynthetic electron transport chain of oxygenic photosynthesis
Oxygenic photosynthesis, performed by plants, algae, and cyanobacteria, is the major route by which solar energy is converted into chemical energy on earth. This process provides the essentials (e.g., food and fuels) for humans to survive and is responsible for oxygenating the earth's atmosphere, which allowed the evolution of multicellular life. Photon energy is harvested during the so-called “light reactions” and used to extract electrons from water, which are then transported through an electron transport chain—in a type of bioelectric current—that is coupled to the movement of protons across the thylakoid membrane, storing energy in the form of a proton electrochemical gradient. The net result of the light reactions is the synthesis of adenosine triphosphate and reduced nicotinamide adenine dinucleotide phosphate, which are used by the “dark” or “light-independent” reactions to convert carbon dioxide into carbohydrates in the Calvin–Benson cycle. In this study, we summarize the structure and function of the main redox-active proteins involved in electron transfer and highlight some recent developments aiming to enhance the efficiency and robustness of the light reactions
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