Simultaneous identification of the low-field-induced tiny variation of complex refractive index for anisotropic and opaque magnetic-fluid thin film by a stable heterodyne Mach-Zehnder interferometer

We use a heterodyne Mach-Zehnder interferometer to simultaneously and simply measure the complex refractive index by only normal incidence on the specimen, instead of using a complicated measurement procedure or instrument that only measures the real or imaginary part of the complex refractive index. To study the tiny variation of the complex refractive index, the small complex refractive-index variation of a rare-concentration magnetic-fluid thin film, due to a weak field of less than 200 Oe, was processed by this interferometer. We also present the wavelength trend of the complex refractive index of magnetic fluids to verify the appearance of the slight change in a small wavelength range. (C) 2009 Optical Society of Americ

Scanning waveform analysis of a room-temperature-probe SQUID NDE system

A room-temperature-probe SQUID NDE system with high mobility and excellent spatial resolution has been developed for detecting the internal cracks of metallic material. Here, the sensing probe is composed of quadruple excitation coils and double D-shape pickup coils. It is connected to the input coil surrounding the SQUID sensor to transfer a magnetic field of eddy current. Following the previous demonstration of its good spatial resolution and high sensitivity, a signal mechanism for the scanning waveform is further proposed in this study to explain the scanning non-directionality of the system and analyze the internal cracks. Both fine and wide single cracks and multi-cracks with dense and spare intervals are valid. Moreover, the model is in good agreement with the test results. (C) 2010 Elsevier Ltd. All rights reserved

In Vivo and Real-Time Measurement of Magnetic Nanoparticles Distribution in Animals by Scanning SQUID Biosusceptometry for Biomedicine Study

Magnetic nanoparticles have been widely applied to biomagnetism, such as drug deliver, magnetic labeling, and contrast agent for in vivo image, etc. To localize the distribution of these magnetic particles in living organism is the first important issue to confirm the effects of magnetic nanoparticles and also evaluate the possible untoward effects. In this study, a scanning high T(c) rf-SQUID superconducting quantum interference devices (SQUIDs) biosusceptometry, composed of static SQUID unit and scanning coil sets, is developed for biomedicine study with the advantages of easy operation and unshielded environment. The characteristics tests showed that the system had the low noise of 8 pT/Hz at 400 Hz and the high sensitivity with the minimum detectable magnetization around 4.5 x 10(-3) EMU at distance of 13 mm. A magnetic nanoparticle detection test, performed by ex vivo scanning of the magnetic fluids filled capillary under swine skin for simulation of blood vessels in living bodies, confirmed that the system is feasible for dynamic tracking of magnetic nanoparticles. Based on this result, we performed further studies in rats to clarify the dynamic distribution of magnetic nanoparticle in living organism for the pharmacokinetics analysis like drug delivers, and propose the possible physiological metabolism of intravenous magnetic nanoparticles

Spatial Recognition of a Superconducting Quantum Interference Devices Nondestructive Evaluation System Using a Small Room-Temperature Probe

A superconducting-qantum-interference-device (SQUID) nondestructive evaluation (NDE) system using a small room-temperature probe is developed for active scanning rather than for a massive movement occurring in a traditional SQUID NDE system. The small room-temperature probe is composed of a quadruple excitation coil and a double D-shaped pickup coil. It is connected to the input coil surrounding a high-T(c) rf SQUID, immersed in liquid nitrogen, and shielded by a shielding can. Beyond the NDE function, the SQUID NDE scheme has spatial recognition functions, including the detection of the orientation and depth of a narrow line crack using different parameters, and the scanning of images of large objects with arbitrary shapes. Furthermore, the spatial sensitivity, limited by the size of the probe, reaches up to only 7 mu m in the aspect of crack widths and 1 mm in the aspect of spatial intervals for precision NDE on a printed circuit board. (C) 2009 The Japan Society of Applied Physic

Fabrication and characterization of InGaN-based green resonant-cavity LEDs using hydrogen ion-implantation techniques

The InGaN-based green resonant-cavity light-emitting diodes (RCLEDs) have been fabricated using hydrogen ion-implantation and laser liftoff techniques. The RCLEDs structure consisted of an InGaN/GaN multiple-quantum-well active layer between the top (5 pairs) and bottom (7.5 pairs) dielectric TiO2/SiO2 distributed Bragg reflectors with optical reflectance of 85% and 99.9%, respectively. The insulation layers of the RCLEDs with and without H+ implantation were formed by the hydrogen ion-implantation layers of 1x10(14) ions/cm(2) concentration and SiO2 film, respectively. The corresponding forward turn-on voltage at 0.6 kA/cm(2) dc current density injection were about similar to 4.58 V and similar to 4.55 V for the RCLEDs with and without H+ implantation. The light output intensity of the RCLEDs with H+ implantation is higher by a factor of 1.4 as compared to that of the similar structure without H+ implantation at a current density of 0.6 kA/cm(2). The directionality of RCLEDs with H+ implantation is superior to that of RCLEDs without H+ implantation. (c) 2007 The Electrochemical Society

In-Vivo and Fast Examination of Iron Concentration of Magnetic Nano-Particles in an Animal Torso via Scanning SQUID Biosusceptometry

To determine the iron concentration of administrated magnetic nano-particles in animals is essential for evaluation of arrival efficiency in target regions in biomagnetism studies. In this work, a high T(c) superconucting quantum interference devices (SQUID) biosusceptometry with a scanning coil set is developed. The measurement principal is based on the AC susceptibility of magnetic nano-particles, and the low noise of 8 pT/root Hz at 400 Hz is characterized in unshielded environment. The dextran-coated magnetic nano-particle of 50 nm in diameter is administrated intravenously into Wistar male rats to demonstrate the in-vivo and fast examination feasibility of this instrument. The in-vivo results of heart region and liver region explained the reasonable biological phenomenon of magnetic nano-particles in animals. Good correlation of concentration-time curve between the induction-coupled-plasma (ICP) and in-vivo examination by AC susceptibility measurement in rat liver region until 4 hours after injection of magnetic naoparticle validates the in-vivo measurement of iron concentration. After 4 hrs post magnetic nanoparticle injection, the phagocyted magnetic nano-particles in liver tissue shows antiferromagnetism properties and explain the difference between the low in-vivo intensity by AC susceptibility measurement and high intensity by ICP

High-Performance InGaN-Based Green Resonant-Cavity Light-Emitting Diodes for Plastic Optical Fiber Applications

High-performance InGaN-based green resonant-cavity light-emitting diodes (RCLEDs) with a plating Cu substrate for plastic optical fiber communication applications are reported. Good stability of emission wavelength was obtained at 0.016 nm/mA. The RCLEDs presents low temperature dependence, showing only a 3% drop in light output power as the temperature increasing from 25 to 85 degrees C. The superior performance can be attributed to the decreased dynamic series resistance and the enhanced thermal dissipation of the heat sink substrate

Immunomagnetic reduction assay using high-T-c superconducting-quantum-interference-device-based magnetosusceptometry

Via immunomagnetic reduction assay, biomolecules can be quantitatively detected with aid of biofunctionalized magnetic nanoparticles, which are used as labeling markers for specific biomolecules. To achieve ultra-high sensitivity in detecting biomolecules, superconducting quantum interference device (SQUID) is a promising candidate to act as a sensor to the magnetic signal related to the concentration of detected biomolecules. In the past, we developed a single channel SQUID-based magnetosusceptometry. In order to increase the detection through-put, multichannel SQUID-based magnetosusceptometry is developed. In this work, the design and working principle of four-channel SQUID-based magnetosusceptometry are introduced. Using utilizing scanning technology, four samples can be simultaneously logged into the SQUID-based magnetosusceptometry. Notably, only single SQUID magnetometer is used in the magnetosusceptometry. The precision and sensitivity in detecting biomolecules using the four-channel SQUID-based magnetosusceptometry are investigated. (C) 2010 American Institute of Physics. [doi:10.1063/1.3340861

Immunomagnetic reduction assay for nervous necrosis virus extracted from groupers

Nervous necrosis virus (NNV) is the cause of viral nervous disease, which is a serious constraint on production for grouper aquaculture. Real-time PCR is commonly used to detect and quantify NNV, has the disadvantages of being expensive and technically demanding. In this study, an immunomagnetic reduction (IMR) assay was developed as a rapid and cost-effective alternative to real-time PCR. This method used magnetic nanoparticles conjugated with antibodies specific for viral surface antigens to detect NNV in grouper tissue samples. The association of NNV with the antibody-conjugated magnetic particles resulted in a reduction in magnetic signal, which was strongly correlated with the concentration of NNV, as determined by real-time PCR. Grouper larvae were prepared for testing using a viral extraction buffer which provided a rapid, 15-min method of extracting viral antigens and had an extraction efficiency of higher than 80%. In addition, this study proposes using magnetic nanoparticles as labeling markers and as an assaying reagent for NNV. The magnetic nanoparticles are functionalized with antibodies against the viral surface of NNV and are able to associate specifically with NNV. The reduction of the magnetic signals comes from the association between magnetic particles and NNV, and relates to the concentration of NNV. The results show that the detected concentrations of NNV are highly correlated to those detected by real-time PCR. (C) 2012 Elsevier BM. All rights reserved

Feasibility studies for assaying alpha-fetoprotein using antibody-activated magnetic nanoparticles

Some previous reports have already shown the characterizations of immunomagnetic reduction (IMR). The assay technology involves the utilities of biofunctionalized magnetic nanoparticles to label target biomolecules. However, the detection threshold and interference tests for IMR have not been investigated in detail. In this study, alpha-fetoprotein (AFP) was used as a target biomolecule. The signals for AFP solutions of various concentrations, or with interfering materials, were detected via IMR. These samples were also used for characterizing the detection threshold and interference with enzyme-linked immunosorbent assay (ELISA). The results of assaying AFP level with IMR and ELISA were compared. The detection threshold for assaying AFP with IMR was found to be 3 ng/mL, which is 15 times lower than that of ELISA, and definitely suppresses false negative. For the interfering materials noted commonly in serum such as hemoglobin, bilirubin, triglyceride, and vascular endothelial growth factor, there was no detectable interfering effect when assaying AFP with IMR. Several serum samples from normal people and liver-tumor-bearing patients were used for the detections of AFP concentration via IMR. These results reveal the feasibilities of assaying AFP in blood using IMR, as well as achieving high-sensitive and high-specific assay for AFP