Microfiber interferometric acoustic transducers.

Acoustic and ultrasonic transducers are key components in biomedical information technology, which has been applied in medical diagnosis, photoacoustic endoscopy and photoacoustic imaging. In this paper, an acoustic transducer based on Fabry-Perot interferometer (FPI) fabricated in a microscaled optical fiber is demonstrated. The transducer is fabricated by forming two wavelength-matched Bragg gratings into the microfiber by means of side illumination with a 193nm excimer laser.

Polarimetric multi-mode tilted fiber grating sensors.

The polarimetric sensing characteristics of multi-mode-fiber based tilted fiber Bragg gratings (MMF-TFBG) have been analyzed and experimentally demonstrated. The larger diameter fiber core and graded index core/cladding profile enable the tilted gratings to excite multiple high-order core modes with significantly different polarization dependence and to form a well-defined "comb" of spectrally separated resonances at different wavelengths. Orientation-recognized twist/rotation measurements (-90° to 90°) have been achieved with sensitivity of 0.

Sensitivity enhancement of Faraday effect based heterodyning fiber laser magnetic field sensor by lowering linear birefringence.

In this paper, we demonstrate that the sensitivity of Faraday effect based heterodyning fiber laser sensors for magnetic field can be effectively enhanced by lowering the intrinsic linear birefringence inside the fiber laser cavity. Well explained by theoretical analysis and confirmed by birefringence tuning through transversal force, it shows that the sensitivity to magnetic field intensity is inversely proportional to the linear birefringence. A CO(2)-laser treatment is therefore proposed to tune the intra-cavity linear birefringence.

In-situ detection of density alteration in non-physiological cells with polarimetric tilted fiber grating sensors.

Tilted fiber Bragg grating (TFBG) biosensors can be used as a cost-effective and relatively simple-to-implement alternative to well established biosensor platforms for high sensitivity biological sample measurements in situ or possibly in vivo. The fiber biosensor presented in this study utilizes an in-fiber 12° tilted Bragg grating to excite a strong evanescent field on the surface of the sensor over a large range of external medium refractive indices. The devices have minimal cross-sensitivity to temperature and their fabrication does not impact the structural integrity of the fiber and its surface functionalization.

Bending effect on modal interference in a fiber taper and sensitivity enhancement for refractive index measurement.

We demonstrate the bending effect of microfiber on interference fringes in a compact taper-based modal interferometer and sensitivity for refractive index (RI) measurement. For the bend curvature ranging from 0 to 0.283 mm(-1), the measured RI sensitivity distinctively increases from 342.

An effect of alginate on the stability of LDH nanosheets in aqueous solution and preparation of alginate/LDH nanocomposites.

Nanosheets under 10nm in thickness are obtained by exfoliating layered double hydroxide (LDH) in formamide. The LDH nanosheets are dispersed and stabilized in an alginate aqueous solution after removing formamide by water washing and ultracentrifugation. During the water washing stage LDH nanosheets can be prevented from restacking by electrostatic stabilization of the surface of LDH sheets through the adsorption of alginate.

Constitutive expression of a rhIL-2-HSA fusion protein in Pichia pastoris using glucose as carbon source.

A constitutive expression vector for rhIL-2-HSA fusion protein production in yeast Pichia pastoris was constructed. The coding gene was placed in frame with the Saccharomyces cerevisiae α-factor secretion signal sequence under the control of the GAP promoter. The recombinant plasmid pGAPZαA-rhIL-2-HSA was integrated into the genome of the P.

In-line microfluidic refractometer based on C-shaped fiber assisted photonic crystal fiber Sagnac interferometer.

We propose and demonstrate a highly sensitive in-line photonic crystal fiber (PCF) microfluidic refractometer. Ultrathin C-shaped fibers are spliced in-between the PCF and standard single-mode fibers. The C-shaped fibers provide openings for liquid to flow in and out of the PCF.

VCSEL-powered and polarization-maintaining fiber-optic grating vector rotation sensor.

A compact fiber-optic vector rotation sensor in which a short section of polarization-maintaining (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single mode fiber without any lateral offset is proposed and experimentally demonstrated. Due to the intrinsic birefringence of the PM fiber, two well-defined resonances (i.e.

Multiwavelength narrow linewidth erbium-doped fiber laser based on FP-LDs.

In this paper, we propose and demonstrate a technique to realize multiwavelength operation in erbium-doped fiber lasers (EDFLs) by inserting two Fabry Pérot laser diodes (FP-LDs) in the laser cavity respectively in cascaded and parallel way. The FP-LDs not only act as wavelength selection elements, but also offer optical gain or loss for the operation wavelengths in the laser cavity. The gains or losses for the oscillation wavelengths obtained from FP-LDs differ with adjustment of the driving current of the FP-LDs.

Ampere force based magnetic field sensor using dual-polarization fiber laser.

A magnetic field sensor is proposed by placing a dual-polarization fiber grating laser under a copper wire. With a perpendicular magnetic field applied, an electrical current flowing through the copper wire can generate Ampere force to squeeze the fiber grating laser, resulting in the birefringence change inside the laser cavity and hence the change of the beat note frequency. When an alternating current is injected into the copper wire, the magnetic field induced beat note frequency change can be discriminated from environment disturbances.

Tunable single frequency fiber laser based on FP-LD injection locking.

We propose and demonstrate a tunable single frequency fiber laser based on Fabry Pérot laser diode (FP-LD) injection locking. The single frequency operation principle is based on the fact that the output from a FP-LD injection locked by a multi-longitudinal-mode (MLM) light can have fewer longitudinal-modes number and narrower linewidth. By inserting a FP-LD in a fiber ring laser cavity, single frequency operation can be possibly achieved when stable laser oscillation established after many roundtrips through the FP-LD.

Characteristics of microfiber Fabry-Perot resonators fabricated by UV exposure.

We inscribe a Fabry-Perot (FP) resonator in the microfiber utilizing the 193-nm UV exposure and the phase mask technique. Some new characteristics including strong polarization dependence and large spectral dispersion in contrast to the conventional counterparts are measured, which are attributed to the two-fold symmetry of index change in the grating and the dispersion of the effective grating length, respectively. The thinner microfiber can generally generate stronger polarization dependence.

Nonlinearity mitigation for high-speed optical OFDM transmitters using digital pre-distortion.

Optical orthogonal frequency-division multiplexing (OOFDM) signal is sensitive to nonlinear distortions induced by optical modulators. We propose and experimentally demonstrate a digital pre-distortion (DPD) algorithm to linearize the optical modulators including electro-absorption modulated lasers (EML) and Mach-Zehnder modulators (MZM) used in high-speed OOFDM transmitters. By using an adaptive DPD algorithm with a learning structure, the inverse transfer function of a modulator, which is based on a polynomial model, has been obtained.

Culture and differentiation of rat neural stem/progenitor cells in a three-dimensional collagen scaffold.

A stable and fast method for constructing a neural-like tissue from rat neural stem/progenitor cells (rNS/PCs) based on three-dimensional (3D) collagen gel is described. First step, the collagen-embedded rNS/PCs expanded with the medium consisting of DMEM/F12/RPMI1640 (1:1:1) supplemented with EGF and bFGF was used to expand the cells in gel in 96-well plates until the average diameter of cell clusters was about 50-100 μm with the cell density higher than 10(7) cells/mL. In the second step, the initial medium was replaced with NB/B-27 supplemented with bFGF and BDNF.

[Distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta].

Applying the method of physical fractionation, distribution characteristics of soil organic carbon and its composition in Suaeda salsa wetland in the Yellow River delta were studied. The results showed that the heavy fraction organic carbon was the dominant component of soil organic carbon in the studied region. There was a significantly positive relationship between the content of heavy fraction organic carbon, particulate organic carbon and total soil organic carbon.

Faraday-rotation-based miniature magnetic field sensor using polarimetric heterodyning fiber grating laser.

A polarimetric heterodyning fiber grating laser is proposed to sense a magnetic field. When a magnetic field is parallel to the fiber grating laser, a circular birefringence is induced into the laser cavity. An elliptical birefringence results due to the circular birefringence and the intrinsic linear birefringence of the laser cavity.

Polarization-maintaining fiber-optic-grating vector vibroscope.

A fiber-optic vector vibroscope based on orthogonal polarization cladding-to-core recoupling is demonstrated. A compact structure in which a short section of polarization-maintained (PM) fiber stub containing a straight fiber Bragg grating (FBG) is spliced to another single-mode fiber. Two well-defined orthogonally polarized cladding modes reflected by the PM-FBG are recoupled at the junction and the coupling intensity shows an extremely high sensitivity to bending in the corresponding orthogonal directions.

Potential for simultaneous strain and temperature sensing based on Brillouin scattering in an all-solid photonic bandgap fiber.

We identify the Brillouin scattering spectrum in both the core and the cladding of an all-solid photonic bandgap fiber for the first time to our knowledge. A multipeak Brillouin spectrum with several frequency shifts and particular linewidths is investigated and related to the structural properties accordingly. Because of the different frequency dependences on the surroundings in the core and the cladding, the proposed structure exhibits potential for use as simultaneous temperature and strain sensors.

Microfiber Mach-Zehnder interferometer based on long period grating for sensing applications.

A Mach-Zehnder interferometer (MZI) composed by a pair of long period gratings (LPGs) fabricated in silica microfiber for sensing applications is demonstrated. Each LPG is fabricated with a pulsed CO2 laser by creating six periodical deformations along fiber length with only one scanning cycle. The length of the MZI can reach as short as 8.

11β-hydroxysteroid dehydrogenase type 1 gene knockout attenuates atherosclerosis and in vivo foam cell formation in hyperlipidemic apoE⁻/⁻ mice.

Background: Chronic glucocorticoid excess has been linked to increased atherosclerosis and general cardiovascular risk in humans. The enzyme 11β-hydroxysteroid dehydrogenase type 1 (11βHSD1) increases active glucocorticoid levels within tissues by catalyzing the conversion of cortisone to cortisol. Pharmacological inhibition of 11βHSD1 has been shown to reduce atherosclerosis in murine models.

Genetic manipulation of sex ratio for the large-scale breeding of YY super-male and XY all-male yellow catfish (Pelteobagrus fulvidraco (Richardson)).

Yellow catfish has become one of the most important freshwater aquaculture species in China. The mono-sex male yellow catfish has important application value in aquaculture because the male grows generally faster than the sibling females under the same conditions. This study has screened YY super-male and YY physiological female yellow catfish by sex reversal, gynogenesis, and progeny testing, which can help to achieve the large-scale production of YY super-male and XY all-male.

Temperature compensated microfiber Bragg gratings.

In this paper, temperature compensated microfiber Bragg grating (mFBG) is realized by use of a liquid with a negative thermo-optic coefficient. The effects of grating elongation and the index change of silica glass are compensated by refractive index change of the liquid through evanescent-field interaction. A reduced thermal sensitivity of 0.

Structural microfiber long-period gratings.

We experimentally demonstrate a novel structural long-period grating by helically coiling one microfiber onto another with the relatively thicker diameter. Owing to the strong periodic modulation of the coiled microfiber to the evanescent field of the straight microfiber, a resonance transmission notch of ~16.2 dB can be induced for a compact device length of ~450 μm only (4 helical periods).

Absence of Yps7p, a putative glycosylphosphatidylinositol-linked aspartyl protease in Pichia pastoris, results in aberrant cell wall composition and increased osmotic stress resistance.

Recently, studies performed on Saccharomyces cerevisiae and Candida albicans have confirmed the importance of fungal glycosylphosphatidylinositol (GPI)-anchored aspartyl proteases (yapsins) for cell-wall integrity. Genome sequence annotation of Pichia pastoris also revealed seven putative GPI-anchored aspartyl protease genes. The five yapsin genes assigned as YPS1, YPS2, YPS3, YPS7 and MKC7 in P.