Performance failure analysis of EDFA cascades in optical DWDM packet-switched networks

A simple and comprehensive technique to determine the probability that a cascade of erbium-doped fiber amplifiers (EDFAs) may be driven into unacceptable regimes of bit error rate (BER) and/or gain levels is presented. This technique allows network designers to determine the tolerances by which the signal power levels may deviate from their predesigned average values and still give acceptable gain variances and BERs at the receiver. We show that even in the signal power range well above the receiver sensitivities (-38 dBm/ch) where the gain spread is not significant, the corresponding spread in BER due to random arrival of packets might result in unacceptable performance. We show for typical levels of operation, the BER temporarily (for about 3 /spl mu/s) deviates to below 10/sup -9/ (10/sup -15/) with a probability of 10/sup -3/ (10/sup -2/), for 100 (64) channels. We show that the gain spread for a single EDFA can be negligible for a range of signal and pump powers at a given average gain.     

The effect of pre-polymer/cross-linker storage on the elasticity and reliability of PDMS microfluidic devices

Polydimethylsiloxane (PDMS) is a commonly used material in biomedical engineering (Sollier et al. in Lab Chip 11(22):3752–3765, 2011; Palchesko et al. in PLoS ONE 7(12):e51499, 2012; Berthier et al. in Lab Chip 12(7):1224–1237, 2012). Its elastic nature makes PDMS especially attractive for microfluidic large-scale integration (mLSI) technology where micromechanical valves are actuated by deflecting a PDMS membrane under pressure. Therefore, understanding and control of PDMS elastic properties have commercial and scientific significance. In this study, we have investigated the effects of pre-polymer/cross-linker storage conditions on the mechanical properties of cured PDMS films as well as on microfluidic devices. We have showed that when the uncured components of PDMS are exposed to different humidity conditions, the elasticity of the PDMS changes and this is revealed as a change in the Young’s modulus of the cured PDMS. The high humidity (~85%) exposure for 24 h causes PDMS to become softer as confirmed by a significant decrease in the Young’s modulus values from 1.2 to 0.9 MPa. Furthermore, as the PDMS is exposed to high humidity conditions for longer periods (72 h), the Young’s modulus decreases down to 0.7 MPa. We found that exposing only the pre-polymer PDMS (Part A) to humid air does not alter the cured PDMS properties significantly, whereas exposure of the cross-linker (Part B) is responsible for the elasticity change. We have strictly controlled the storage humidity to build more reliable microfluidic chips using mLSI. As a result, actuation pressure of valves (10 psi) and defects of devices (in <30% of chips) are significantly reduced. These results suggest that to improve the manufacturing yield and reliability of PDMS devices, storage humidity should be controlled immediately after the material synthesis.     

Potential Modulated Attenuated Total Reflectance Spectroscopy of Prussian Blue Films on ITO

Potential modulated attenuated total reflectance (PM-ATR) spectroscopy has been employed to study charge transfer processes in Prussian blue (PB) films deposited on indium tin oxide (ITO) electrodes. PM-ATR is a planar waveguide-based spectroelectrochemical technique in which the optical response of an electroactive film is measured as a function of applied potential and modulation frequency. The multiple internal reflection geometry of PM-ATR provides a significant sensitivity advantage over the single external reflectance geometry that has been employed in most prior electroreflectance studies. The apparent electron transfer rate of PB on ITO obtained using PM-ATR was compared to that obtained with conventional cyclic voltammetry; the respective rates, 0.33 ± 0.15 s⁻¹ (n = 3) and 0.71 ± 0.37 s⁻¹ (n = 10), are in good agreement.     

Statistical design of experiments as a tool for optimizing the batch conditions to Cr(VI) biosorption on Araucaria angustifolia wastes

In order to reduce the total number of experiments for achieving the best conditions for Cr(VI) uptake using Araucaria angustifolia (named pinh?o) wastes as a biosorbent, three statistical design of experiments were carried out. A full 2(4) factorial design with two blocks and two central points (20 experiments) was experimented (pH, initial metallic ion concentration-C(o), biosorbent concentration-X and time of contact-t), showing that all the factors were significant; besides, several interactions among the factors were also significant. These results led to the performance of a Box-Behnken surface analysis design with three factors (X, C(o) and t) and three central points and just one block (15 experiments). The performance of these two statistical designs of experiments led to the best conditions for Cr(VI) biosorption on the pinh?o wastes using a batch system, where: pH 2.0; C(o) = 1200 mg l(-1) Cr(VI); X = 1.5 g l(-1) of biosorbent; t = 8 h. The maximum Cr(VI) uptake in these conditions was 125 mg g(-1). After evaluating the best Cr(VI) biosorption conditions on pinh?o wastes, a new Box-Behnken surface analysis design was employed in order to verify the effects of three concomitant ions (Cl(-), NO(3)(-) and PO(4)(3-)) on the biosorption of Cr(VI) as a dichromate on the biosorbent (15 experiments). These results showed that the tested anions did not show any significant effect on the Cr(VI) uptake by pinh?o wastes. In order to evaluate the pinh?o wastes as a biosorbent in dynamic system, a glass column was fulfilled with pinh?o wastes (4.00 g) as biosorbent, and it was fed with 25.0 mg l(-1) Cr(VI) at pH 2.0 and 2.5 ml min(-1). The breakpoint was attained when concentrations of effluent of the column attained the value of 0.05 mg l(-1) Cr(VI) using 5550 ml of the metallic ion solution. In these conditions, the biosorbent was able to remove completely Cr(VI) from aqueous solution with a ratio of Cr(VI) effluent volume/biosorbent volume of 252.3.     

The mediating effect of rewarding on the relationship between employee involvement and job satisfaction

Employee support provides enormous benefits to help sustain a competitive advantage, respond to changes more quickly than competitors, and position the organization ahead of others. Awareness of this fact triggers organizations to prepare new motivational programs and practices. Employee involvement and rewards are among the many ways to achieve employee job satisfaction and motivational needs. Employee involvement entails giving employees an opportunity to influence decisions and actions regarding their jobs. Furthermore, rewards have the potential to prompt employees to act in line with organizational goals. This study aims to examine the relationship between employee involvement and job satisfaction based on the mediation effect of rewarding. Four hundred employees from the financial sector responded to a questionnaire. The relationship between employee involvement and job satisfaction was tested using hierarchical linear regression analysis. Results revealed that rewarding does mediate the relationship between employee involvement and job satisfaction. Organizations that give priority to employee needs and motivational processes should take both employee involvement and rewarding into consideration.     

Adsorption of Cu(II) on Araucaria angustifolia wastes: determination of the optimal conditions by statistic design of experiments

Wastes of Araucaria angustifolia (named pinh?o) natural (PW) and also loaded with Congo red (CRP) were tested as low-cost adsorbents for Cu(II) removal from aqueous solutions. In order to reduce the total number of experiments to achieve the best conditions of the batch adsorption procedure, three sets of statistical designs of experiments were carried-out for each adsorbent. Initially, a full 2(4) factorial design for each adsorbent with two central points (18 experiments) were performed, to optimize the following factors: mass of adsorbent (m), pH, time of contact (t) and initial metallic ion concentration (Co). These results indicated that almost all the main factors and its interactions were significant. It was verified for both adsorbents, that a mass of 30.0mg leaded to higher Cu(II) uptake and that the best pH for Cu(II) adsorption was 5.6. In order to continue the batch adsorption optimization of the systems, a central composite surface analysis design with two factors (Co, t) containing 13 experiments, divided in to four cube points, four axial points and five centre points was carried-out for each adsorbent. By performing these two sets of statistical design of experiments, the best conditions for Cu(II) uptake using pinh?o wastes (PW) and pinh?o wastes loaded with Congo red (CRP) using batch adsorption system, where: m=30.0mg of adsorbent; pH 5.6; t=2.5h. After optimizing the batch adsorption system by statistical design of experiments, isotherms for Cu(II) uptake using PW and CRP were performed. These isotherms fitted to the linear Langmuir and Freundlich models.     

Nanoamorphous carbon as a blackbody source in plasmonic thermal emitters

Ag/dielectric/Ag-type plasmonic thermal emitters (PTEs) following a hexagonal lattice were fabricated, and their plasmonic emission spectrums were characterized with Fourier transform infrared spectroscopy. Nanoamorphous carbon (NAC) is used as a dielectric layer. Doping NAC with various materials over a wide range of levels enables control of the resistivity of the composite films where MoSi(2) was selected as the dopant. Wavelength tuning in the range of 4-7 μm is demonstrated by changing the conductivity of the composite films as well as the lattice periodicity of the hexagonal lattice. We also tested the mechanical stability of the PTEs under mechanical strains.