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1.
Prion proteins that have transformed from their normal cellular counterparts (PrPc) into infectious form (PrPres) are responsible for causing progressive neurodegenerative diseases in numerous species, such as bovine spongiform encephalopathy (BSE) in cattle (also known as mad cow disease), scrapie in sheep, and Creutzfeldt-Jakob disease (CJD) in humans. Due to a possible link between BSE and CJD it is highly desirable to develop non-invasive and ante mortem tests for the detection of prion proteins in bovine samples. Such ante mortem tests of all cows prior to slaughter will help to prevent the introduction of PrPres into the human food supply. Furthermore, detection of PrPres in donated blood will also help to prevent the transmission of CJD among humans through blood transfusion. In this study, we have continued development of a micromechanical resonator array that is capable of detecting PrPc in bovine blood serum. The sensitivity of the resonators for the detection of PrPc is further enhanced by the use of secondary mass labels. A pair of antibodies is used in a sandwich immunoassay format to immobilize PrPc on the surface of resonators and attach nanoparticles as secondary mass labels to PrPc. Secondary mass labeling is optimized in terms of incubation time to maximize the frequency shifts that correspond to the presence of PrPc on the surface of resonators. Our results show that a minimum of 200 pg mL−1 of PrPc in blood serum can be detected using micromechanical resonator arrays. 相似文献
2.
P. Grangier J.-P. Poizat 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》1999,7(1):99-105
By generalizing recently obtained results we calculate the excess noise factor (Petermann factor) for a laser system with
non-orthogonal eigenmodes. The quantum consistency of the calculation is shown through the explicit conservation of input-output
commutation rules. As a result of the calculation, the excess noise in the lasing mode is shown to depend on the laser gain
below threshold, and on the noise analysis frequency below and above threshold.
Received: 27 October 1998 / Received in final form: 11 March 1999 相似文献
3.
K.I. Petsas A. Gatti L.A. Lugiato C. Fabre 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):501-512
We investigate the spatial behaviour of the quantum-noise-reduction spectrum of the vacuum state emitted by a degenerate optical
parametric oscillator below threshold. In view of possible experimental implementations, we consider a mode-degenerate resonator
and two matching lenses and show that, for the realistic case of a finite-width pump, significant level of squeezing can be
observed in a very small region of the beam.
Received 25 September 2002 Published online 11 February 2003 相似文献
4.
We investigate a new parallel all-optical clock recovery scheme based on heterodyne beats of an optical sideband-filtered signal. The oscillating clock signal is recovered when the filtered sideband is combined with a stable local oscillator. The filtering is performed with an optical resonator, which by nature provides possibility for multiwavelength operation. The local oscillator could be realized by a multiwavelength laser, whose emission wavelengths are injection seeded with carrier wavelengths of the input data. The output signal of such a configuration benefits from a reduced bit-pattern effect and a stable offset level. The sideband filtering is demonstrated for 23 simultaneous channels at 100 GHz DWDM grid, each hosting a data stream of 10 Gbit/s. 相似文献
5.
T. A. Nguyen H. T. Dung 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2008,46(1):173-177
Using the Born expansion of the Green tensor, we consider the
spontaneous decay rate of an excited atom placed in the vicinity of
a rectangular plate. We discuss the limitations of the commonly used
simplifying assumption that the plate extends to infinity in the lateral
directions and examine the effects of the atomic dipole moment
orientation, atomic position, and plate boundary and thickness on the atomic
decay rate. In particular, it is shown that
due to the plate finite size, the spontaneous decay may be inhibited
even when the atom is situated very close to the surface, and that
in the boundary region, the
spontaneous decay rate can be strongly modified. 相似文献
6.
Coupled extension and thickness-twist vibrations of lateral field excited AT-cut quartz plates简 总被引:1,自引:0,他引:1
Ting-Feng Ma Rong-Xing Wu Ji Wang Jian-Ke Du Li-Li Yuan Fa-Peng Yu Chao Xie 《Acta Mechanica Sinica》2014,30(1):67-72
In this paper, the coupled extension and thickness- twist vibrations are studied for AT-cut quartz plates under Lateral Field Excitation (LFE) with variations along the x1- direction. Mindlin's two-dimensional equations are used for anisotropic crystal plates. Both free and electrically forced vibrations are considered. Important vibration characteristics are obtained, including dispersion relations, frequency spectra, and motional capacitances. It is shown that, to avoid the effects of the couplings between extension and thickness-twist vibrations, a series of discrete values of the length/thickness ratio of the crystal plate need to be excluded. The results are of fundamental significance for the design of LFE resonators and sensors. 相似文献
7.
F. Frezza A. Galli G. Gerosa P. Lampariello 《International Journal of Infrared and Millimeter Waves》1995,16(3):675-688
In this paper the fundamental effects of losses on resonant parameters (frequencies and quality factors) are analyzed for circular-cylindrical dielectric resonators inserted between metal plates, in the configuration also called NRD (Non-Radiative Dielectric).Power dissipations are considered both in the dielectric and in the conductors. Complex resonant frequencies and closed-form expressions for the relevant quality factors are derived rigorously for arbitrary resonant modes, even without circular symmetry. Numerical results are presented and discussed, making also use of experimental data obtained by means of a suitable NRD set-up.The present analysis accurately provides the basic information for a more realistic design of up-to-date millimeter-wave frequency-selective devices in NRD circuitry. 相似文献
8.
Dynamic pull-in phenomenon in MEMS resonators 总被引:1,自引:0,他引:1
We study the pull-in instability in microelectromechanical (MEMS) resonators and find that characteristics of the pull-in
phenomenon in the presence of AC loads differ from those under purely DC loads. We analyze this phenomenon, dubbed dynamic pull-in, and formulate safety criteria for the design of MEMS resonant sensors and filters excited near one of their natural
frequencies. We also utilize this phenomenon to design a low-voltage MEMS RF switch actuated with a combined DC and AC loading.
The new switch uses a voltage much lower than the traditionally used DC voltage. Either the frequency or the amplitude of
the AC loading can be adjusted to reduce the driving voltage and switching time. The new actuation method has the potential
of solving the problem of high driving voltages of RF MEMS switches. 相似文献
9.
We demonstrate and discuss the formation of an intriguing interference fringe pattern that is visible in stable resonators at resonator lengths corresponding to a higher-order frequency-degeneracy. The optical trajectories that form these fringes are described for arbitrary degeneracy; the fringes can be used to visualize and quantify imaging aberrations of the cavity relative to a cavity consisting of ideal mirrors. 相似文献
10.
The out-of-plane vibrations of a generalized thermoelastic circular plate are studied under different environmental temperature, plate dimensions and boundary conditions. The analytical expressions for thermoelastic damping of vibration and phase velocity of circumferential surface wave modes are obtained. It is noticed that the damping of vibrations and phase velocities of circumferential surface wave modes significantly depend on thermal relaxation time in addition to thermoelastic coupling in circular plates under resonance conditions. The surface conditions also impose significant effects on the vibrations of such resonators. The expressions for displacement and temperature fields in the plate resonator are also derived and obtained. Some numerical results have also been presented for illustration purpose in case of silicon material plate. 相似文献