31,592 research outputs found
Optical spectroscopy study on single crystalline LaFeAsO
Millimeter-sized single crystals of LaFeAsO were grown from NaAs flux and the
in-plane optical properties were studied over a wide frequency range. A sizable
electronic correlation effect was indicated from the analysis of the
free-carrier spectral weight. With decreasing temperature from 300 K, we
observed a continuous suppression of the spectral weight near 0.6 eV. But a
spin-density-wave gap formation at lower energy scale was seen only in the
broken-symmetry state. We elaborate that both the itinerancy and local spin
interactions of Fe\emph{3d} electrons are present for the FeAs-based systems;
however, the establishment of the long-range magnetic order at low temperature
has a dominantly itinerant origin.Comment: 4 figures, 5 page
Quantum key distribution over 122 km of standard telecom fiber
We report the first demonstration of quantum key distribution over a standard
telecom fiber exceeding 100 km in length. Through careful optimisation of the
interferometer and single photon detector, we achieve a quantum bit error ratio
of 8.9% for a 122km link, allowing a secure shared key to be formed after error
correction and privacy amplification. Key formation rates of up to 1.9 kbit/sec
are achieved depending upon fiber length. We discuss the factors limiting the
maximum fiber length in quantum cryptography
Quantum computing through electron propagation in the edge states of quantum spin Hall systems
We propose to implement quantum computing based on electronic spin qubits by
controlling the propagation of the electron wave packets through the helical
edge states of quantum spin Hall systems (QSHs). Specfically, two
non-commutative single-qubit gates, which rotate a qubit around z and y axes,
can be realized by utilizing gate voltages either on a single QSH edge channel
or on a quantum point contact structure. The more challenging two-qubit
controlled phase gate can be implemented through the on-demand capacitive
Coulomb interaction between two adjacent edge channels from two parallel QSHs.
As a result, a universal set of quantum gates can be achieved in an
all-electrical way. The fidelity and purity of the two-qubit gate are
calculated with both time delay and finite width of the wave packets taken into
consideration, which can reach high values with the existing high-quality
single electron source
Photovoltaic Oscillations Due to Edge-Magnetoplasmon Modes in a Very-High Mobility 2D Electron Gas
Using very-high mobility GaAs/AlGaAs 2D electron Hall bar samples, we have
experimentally studied the photoresistance/photovoltaic oscillations induced by
microwave irradiation in the regime where both 1/B and B-periodic oscillations
can be observed. In the frequency range between 27 and 130 GHz we found that
these two types of oscillations are decoupled from each other, consistent with
the respective models that 1/B oscillations occur in bulk while the
B-oscillations occur along the edges of the Hall bars. In contrast to the
original report of this phenomenon (Ref. 1) the periodicity of the
B-oscillations in our samples are found to be independent of L, the length of
the Hall bar section between voltage measuring leads.Comment: 4 pages, 4 figure
Generation and characterization of a monoclonal antibody to penicillic acid from Penicillium cyclopium
Penicillic acid is one of the main mycotoxins in moldy feedstuff and has toxic effect on livestock and poultry and probably humans due to food chain transmission. The objective of this study was to generate and characterize a monoclonal antibody to penicillic acid for the efficient detection of penicillic acid from Penicillium cyclopium by immunological methods. To this end, penicillic acid was conjugated to bovine serum album (BSA) using the Mannich reaction and coupled with ovalbumin(OVA) by the method of 1-ethyl-3-(3-dimethyl-aminopropyl) carbodiimide hydrochloride (EDC) to generate artificial antigens penicillic acid-BSA and penicillic acid-OVA. A hybridoma cell line was obtained after fusion of mouse SP2/0 myeloma cells with spleen cells of BALB/c mice immunized with artificial antigen penicillic acid-BSA. A monoclonal antibody specific against penicillic acid was produced in vivo by this hybridoma cell line. Further analysis revealed that the monoclonal antibody to penicillic acid was of the IgG1 subtype, with a titer of 1: 2.05 × 105. The antibody to penicillic acid had no or less cross-reaction with mycotoxins, including aflatoxin B1, zearalenone, T-2 toxin and fumonisins and more importantly, it assumed an affinity of about 1.54 × 108 liters per mol. Our ability to produce a monoclonal antibody to penicillic acid provides necessary groundwork for the effective detection of penicillic acid in various tissues of animals and human, using the immunocytochemistry,Western blots and enzyme-linked immunosorbent assay (ELISA)
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