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Gout is a form of crystal arthropathy where monosodium urate (MSU) crystals deposit and elicit inflammation in a joint. Diagnosis of gout relies on identification of MSU crystals under a compensated polarized light microscope (CPLM) in synovial fluid aspirated from the patient’s joint. The detection of MSU crystals by optical microscopy is enhanced by their birefringent properties. However, CPLM partially suffers from the high-cost and bulkiness of conventional lens-based microscopy, and its relatively small field-of-view (FOV) limits the efficiency and accuracy of gout diagnosis. Here we present a lens-free polarized microscope which adopts a novel differential and angle-mismatched polarizing optical design achieving wide-field and high-resolution holographic imaging of birefringent objects with a color contrast similar to that of a standard CPLM. The performance of this computational polarization microscope is validated by imaging MSU crystals made from a gout patient’s tophus and steroid crystals used as negative control. This lens-free polarized microscope, with its wide FOV (>20 mm2), cost-effectiveness and field-portability, can significantly improve the efficiency and accuracy of gout diagnosis, reduce costs, and can be deployed even at the point-of-care and in resource-limited clinical settings.

In the present study, the immunostimulatory activity of verbascose from mung beans (Phaseolus aureus) was evaluated by using in vitro cell models and in vivo animal models. The results of in vitro experiments showed that verbascose could enhance the ability of devouring neutral red of peritoneal macrophages and promote the release of nitric oxide and immune reactive molecules such as interleukin (IL)-6, IL-1β, interferon (IFN)-α, and IFN-γ. Treatment with verbascose at a dose of 200 μg/mL exhibited the best effects. For assay in vivo, administration of verbascose at a medium dose of 90 mg/kg body weight could significantly increase the index of spleen, activity of lysozyme in spleen and serum, hemolysin level in serum, and swelling rate of earlap in the delayed type of hypersensitivity (DTH) of immunosuppressed mice. All of the results suggested that verbascose had potent immunostimulatory activity and could be explored as a potential natural immunomodulatory agent in functional foods.

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A new quantum measurement scheme of intensity difference fluctuation between two light beams of equal mean intensity is presented. In this system a beam splitter is used as the coupling device and the twin beams with high quantum correlation are injected into its dark port as the input meter wave instead of the usual vacuum field. A measurement satisfying all the quantum nondemolition criteria is experimentally achieved. The measured sum of the transfer coefficients and the conditional variance are, respectively, T s 1 T m 1.31 and V s͞m 22.1 dB. [S0031-9007(99)08445-8] PACS numbers: 42.50.Dv, 03.65.Bz Quantum nondemolition (QND) measurements have attracted extensive interest [1]. Since 1986, a variety of QND-type measurements have been successfully demonstrated in optical experiments [2][3][4][5][6][7][8][9]. In most experiments measurements of the quadrature phases of the probe field were involved to provide the information of signal observables. In a recent paper Harrison et al. [10] have proposed a QND scheme, in which the signal and probe observables are the intensity difference between twin beams on the left and right hand sides of a double ended nondegenerate optical parametric oscillator; therefore, only the field intensities need to be measured rather than the quadrature phases [10]. So far there is no published experimental realization of this QND-type measurement.It is well known that a beam splitter is the simplest optical coupling device [11]. Recently Bruckmeier et al. [9] have realized a quantum measurement satisfying the quantum nondemolition criteria by injection of a 3.7 dB quadrature squeezed wave into the usual vacuum port of a beam splitter. The good results of signal transfer T s 1 T m 1.29 and the conditional variance V s͞m 21.3 dB were obtained. On the other hand great reductions of quantum fluctuations in the intensity difference between twin beams produced by a nondegenerate parametric oscillator were achieved in several groups [12][13][14]. The above-mentioned successful experiments motivated us to design a quantum measurement scheme using a beam splitter, the dark port of which is filled by quantum correlated twin beams instead of a quadrature squeezed wave as in Ref. [9]. When the twin beams with quantum noise reduction in the intensity difference of 76% below the standard quantum limit (SQL) are injected into the vacuum port of a beam splitter, the measurement of intensity difference fluctuation in the quantum domain is experimentally realized. The measured T s 1 T m 1.31 and V s͞m 22.1 dB fulfill the QND criteria introduced by Holland et al. [15] and Poizat et al. [16].At first we simply present the measurement principle of the proposed scheme. S in and M in are, respectively, the signal and meter input waves incident upon the beam splitter (BS) from opposite sides with small angles of incidence; S out and M out are, respectively, the output signal and meter waves. Both S in and M in consist of two orthogonal polarized modes (S polarization and P polarization) of equal mean intensit...

We report low-noise GaN visible-blind homojunction p-i-n photodiodes. The devices are grown on a freestanding bulk GaN substrate and are fabricated using a “ledged” surface depletion technique to suppress the mesa sidewall leakage. For an 80-μm-diameter photodetector, the dark current density is lower than 40 pA/cm2. A room-temperature noise equivalent power of 4.27×10−17 W Hz−0.5 and a detectivity of 1.66×1014 cm Hz0.5 W−1 are achieved at a reverse bias of 20 V. The noise performance of the reverse-biased GaN p-i-n photodiodes are among the best values reported to date and demonstrate the potential of GaN photodiodes for low-noise high-speed UV detection.

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