Extraction of intrinsic response from S-parameters of laser diodes

We describe a new method for extracting the intrinsic response of a laser diode from S-parameters measured using a calibrated vector network analyzer. The experimental results obtained using the new method are compared with those obtained using the optical modulation method and the frequency response subtraction method. Good agreement has been obtained, confirming the new method validity and accuracy. The new method has the advantages of obtaining the intrinsic characteristics of a laser diode with conventional measurements using a network analyzer.     

Praseodymium Rare Earth Doped Tellurite Glasses

Praseodymium (Pr3+)-doped tellurite glasses suitable for planar waveguide device applications at 1.3μm operation have been fabricated and characterized optically. The maximum phonon band of undoped glasses is at 738 cm-1, and the emission from the Pr3+: 1G4→3H5 transition is at 1.33 μm wavelength with a spectral bandwidth of 100nm,The lifetime of the 1G4 level is ～24 us, and the quantum efficiency is ～ 2.6 % which is similar to that in fluorozirconate glasses. The resonant energy transfer between Pr3+ and Yb3+ in tellurite glasses has been investigated. Energy absorbed by Pr3+ is transferred efficiently to Yb3+, and fluorescence around 1.00 μm is observed.     

Erbium Doped Phosphate Glass For Optical Waveguide Amplifier

Erbium (Er3+) doped phosphate glasses was prepared and the optical properties of these glasses were investigated. The emission parameters were calculated using the Judd-Ofelt treatment. The radiative lifetime of the 4I13/2 level is calculated to be 7.2ms. The fluorescence lifetime is measured to be 6ms, and the quantum efficiency is estimated to be 83%. Ion-exchanged optical waveguides were fabricated in these glasses by using pure KNO3 meet at 370℃, and diluted AgNO3 molten salt at 270℃. It was found that the lower temperature diluted AgNO3 molten salt is better for the ion exchange process. Planar waveguide with 5 modes at the 633nm and 2 modes at the 1550nm was demonstrated using the diluted AgNO3. Our results show that phosphate glass is a potential candidate for the 1.5μm optical amplifier device.     

Comparative pharmacology of recombinant rat AT1A, AT1B and human AT1 receptors expressed by transfected COS-M6 cells

1. Currently available antagonists and agonists cannot distinguish between angiotensin AT1 receptor subtypes. 2. We synthesized a series of compounds selected on the basis of having the most diverse structural features with respect to losartan (DuP753), the prototype non-peptide AT1 receptor antagonist. Using a radioligand-receptor binding assay and membranes prepared from COS-M6 cells transfected with individual AT1 receptor subtypes, we determined whether any of these compounds could distinguish between the receptor subtypes. 3. The diversity of the structural features of this series of compounds was reflected by the wide range of affinities (pIC50 values) displayed towards competing with [125I]-Sar1Ile8 angiotensin II for binding to the AT1 receptors. 4. Direct comparisons of the pIC50 values of individual compounds for rat AT1A, AT1B and human AT1 receptors revealed only minor differences. 5. It is concluded that compounds based structurally on losartan are unlikely to distinguish between these receptors.     

NG108-15 cells express neuregulin that induces AChR alpha-subunit synthesis in cultured myotubes

A neural network is a computerized construct consisting of input neurons (which process input data) connected to hidden neurons (to mathematically manipulate values they receive from all the input neurons) connected to output neurons (to output a prediction). Neural networks are created and trained via multiple iterations over data with known results. In 1993, 897 trauma patients were either declared dead in the emergency room (ER; 76 cases), admitted to the intensive care unit (427 cases, 36 deaths), or taken directly to the operating room (394 cases, 29 deaths). Using only data available from the ER, a neural network was created, and 628 cases were randomly selected for training. After 268 iterations, the network was trained to correctly predict death or survival in all 628 cases. This trained network was then tested on the other 269 cases without our providing the death or survival result. Its overall accuracy was 91 per cent (244 of 269 cases). It was able to predict correctly 60 per cent (12 of 20 cases) of the postoperative or post-intensive care unit admission deaths and 90 per cent (26 of 29 cases) of the deaths in the ER. Computerized neural networks can accurately predict a trauma patient's fate based on inital ER presentation. The theory and use of neural networks in predicting clinical outcome will be presented.     

Frequency limitation in the calibration of microwave test fixtures

The problem of frequency limitation arising from the calibration of asymmetric and symmetric test fixtures has been investigated. For asymmetric test fixtures, a new algorithm based on the thru-short-match (TSM) method is outlined. It is found that the conventional TSM method does not have any inherent frequency limitation, but using the same procedure with an unknown match may lead to the said problem. This limitation can be avoided by using a different algorithm. The various calibration methods for symmetric test fixtures using known standards are also discussed and the origin of the frequency limitation is identified. Several ways in avoiding the problem are proposed. There is good agreement between the theories and experimental data.     

Excitation expansion in the high-energy UV region for Dy3+-doped medium-temperature molten silicate glass phosphors

Medium-temperature molten Dy³⁺-doped silicate (LNKBAS) glass phosphors can be excited efficiently in the low-energy ultraviolet region (UVA). To this end, the addition of sensitizers Sb³⁺ and Ce³⁺ expands the validly excitable wavelength of Dy³⁺ from 348 to 248 nm. Fluorescence spectra demonstrate the superposition effect of the sensitization in the high-energy ultraviolet region (UVC), and the multiplicative effect of sensitization in the UVA and medium-energy ultraviolet region (UVB) for Sb³⁺–Ce³⁺–Dy³⁺ tri-doped LNKBAS glass phosphors. The chromaticity coordinate of LNKBASCe_0.04Sb_0.1Dy_1.0 is (0.2725, 0.3031) at 248 nm excitation, and the sensitization coefficient of LNKBASCe_0.04Sb_0.2Dy_1.0 reaches at 19.85 under 309 nm excitation. Static fluorescence photographs and dynamic fluorescence video reveal the excitation expansion and the multiplicative effect of sensitization to Dy³⁺ by adding sensitizers at a macroscopic level. In general, the ideal rare-earth energy conversion in medium-temperature molten silicate glass phosphors offers promising prospects for saving energy and manufacturing high-quality optoelectronic devices.     

SPION nanoparticles as an efficient probe and carrier of DNA to umbilical cord blood-derived mesenchymal stem cells

Superparamagnetic iron oxide nanoparticles (SPION) were used to transfer gene into umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) in this study. This novel transfection method using SPION is safe and effective to UCB-MSCs, and would be a tool for genetic optimization with a significant potential for cell tracing.