Application of N-PLS calibration to the simultaneous determination of Cu(2+), Cd(2+) and Pb(2+) using peptide modified electrochemical sensors

The simultaneous determination of Cu(2+), Cd(2+) and Pb(2+) is demonstrated at four modified gold electrodes using N-PLS calibration. Three of the electrodes were modified with the peptides Gly-Gly-His, gamma-Glu-Cys Gly and human angiotensin I which were covalently attached to thioctic acid self-assembled monolayers and the fourth electrode was modified with thioctic acid only. Voltammetry at the modified electrodes in the presence of the three metal ions revealed one peak due to the reduction of copper and another due to the overlapping peaks of cadmium and lead which made quantification using conventional methods difficult. N-PLS was used to calibrate and predict trace concentrations (100 nM to 10 microM) of mixtures of Cu(2+), Cd(2+) and Pb(2+).     

Transcritical Flow Over a Hole

Transcritical flow over a localized obstacle generates upstream and downstream nonlinear wavetrains. In the weakly nonlinear long-wave regime, this flow has been modeled with the forced Korteweg-de Vries (fKdV) equation, where numerical simulations and asymptotic solutions have demonstrated that the upstream and downstream nonlinear wavetrains have the structure of unsteady undular bores, connected by a locally steady solution over the obstacle. Further, it has been shown that when the obstacle is replaced by a step of semi-infinite length, it is found that a positive step generates only an upstream-propagating undular bore, and a negative step generates only a downstream-propagating undular bore. This result suggests that for flow over a hole, that is a step down followed by a step up, the two wavetrains generated will interact over the hole. In this paper, this situation is explored by numerical simulations of the fKdV equation.     

A linear code parameter search algorithm with applications to immunology

The immune system is modeled by way of a system of ordinary differential equations involving a large number of parameters, such as growth rates and initial conditions. Key to successful implementation of the model is the estimation of such parameters from available data. A parameter search algorithm based on linear codes is developed having as aim the identification of different regimes of behaviour of the model, the estimation of parameters in a high dimensional space, and the model calibration to data. This work was funded under the NIH grant GM67240.     

On derangement polynomials of type B. II

We define a type B derangement polynomial by q-counting derangements by the number of excedances in the hyperoctahedral group Bn. Properties of the derangement polynomial, including the recurrence relation, generating function, real-rootedness, reciprocity and a unimodal decomposition arising from a symmetric function identity, are studied. The results presented generalize and unify earlier ones due to Brenti, Stanley, Stembridge and Zhang.     

10 Gb/s optical carrier distributed network with W-band (0.1 THz) short-reach wireless communication system

Millimeter-wave (mm-wave) operated in W-band (75 GHz–0.11 THz) is of particular interests, since this frequency band can carry signals at much higher data rates. We demonstrate a 10 Gb/s optical carrier-distributed network with the wireless communication system. The mm-wave signal at carrier frequency of 0.1 THz is generated by a high speed near-ballistic uni-traveling carrier photodiode (NBUTC-PD) based transmitter (Tx), which is optically excited by optical short pulses. The optical pulse source is produced from a self-developed photonic mm-wave waveform generator (PMWG), which allows spectral line-by-line pulse shaping. Hence these optical pulses have high tolerance to fiber chromatic dispersion. The W-band 10 Gb/s wireless data is transmitted and received via a pair of horn antennas. The received 10 Gb/s data is envelope-detected and then used to drive an optical modulator at the remote antenna unit (RAU) to produce the upstream signal sending back to the central office (CO). 20 km single mode fiber (SMF) error free transmission is achieved. Analysis about the optimum repetition rate of the optical pulse source and the transmission performance of the upstream signal are also performed and discussed.     

Stable wavelength-tuning laser in single-frequency by optical-injected Fabry-Perot laser diode and RSOA for long fiber distance propagation

In this demonstration, we propose and experimentally investigate a stable wavelength-tuning laser configuration by using self-seeded Fabry-Perot laser diode (FP-LD) and external-injected reflective semi-conductor optical amplifier (RSOA). Here, this proposed laser can be tuned in the wavelength range of 1534.05 to 1553.00 nm with a 1.1 nm tuning-step. And the output powers and side-mode suppression ratios (SMSRs) are measured at −5.3 to 4.6 dBm and 31.2 to 50.1 dB/0.05 nm, respectively. And, the proposed laser also can be directly modulated at 2.5 Gb/s on-off keying (OOK) modulation format and propagates 75 km single-mode fiber (SMF) with no optical amplifier and dispersion compensation.     

Semiconductor optical amplifier-based laser with 25 km long cavity length utilizing sagnac fiber ring structure

In the investigation, we propose and demonstrate a Sagnac ring based fiber laser structure using a semiconductor optical amplifier (SOA) to act as a gain medium with short to long fiber cavity lengths for wavelength lasing and tuning. Here, ten fiber Bragg gratings (FBGs) with different reflected Bragg wave-lengths are used serving as the reflected element in the proposed laser configuration for wavelength lasing and remote sensing simultaneously. Furthermore, the different cavity fiber lengths of a few ten m to 25 km, which are used in the proposed laser scheme, has been analyzed and discussed.     

Thermal and Laser Properties of Nd:YVO4 Crystal

Nd:YVO₄ crystal has been grown by Czochralski method. The data of thermal expansion and specific heat have been measured. The thermal expansion coefficients along a- and c-axis are a₁ = 2.2 x 10^-6 /K, and a₃ = 8.4 x 10^-6 /K respectively. The specific heat is 24.6 cal/mol x K at 330 K. The large anisotropy along c- and a-axis of thermal expansion coefficients is explained by the structure of YVO₄ crystal. 921 mW output laser at 1.06 mikrom has been obtained with a 3 mm x 3 mm x 1mm crystal sample when pumped by 1840 mW cw laser diode, and the slope efficiency is 55.5%.     

NMR imaging as a new tool for rheology

Examples of NMR imaging used to study the evolution of microstructure and flow velocities in sheared, highly filled suspensions are described. Fast NMR imaging methods were used to freeze the motion in a falling-ball experiment, allowing us to monitor the local concentrations of suspended particles and ball position during the course of the experiment The migration of particles induced by shear and concentration gradients was followed in a Couette cell. Flow imaging methods were developed and applied to a Newtonian fluid and a non-Newtonian suspension flowing in an axisymmetric pipe contraction.