Synthesis of porphyrin-PPV copolymers for application in LEDs

A new series of soluble porphyrin-containing copolymers have been synthesized via the Gilch methodology [1], for use in light-emitting devices (LEDs). These materials consist of random copolymers of 2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PPV) and a porphyrin-substituted phenylene vinylene. Low concentrations of porphyrin monomers were used in order to improve solubility, and help prevent aggregation (and consequent fluorescence quenching) of the porphyrin units. Emission is red-shifted from that expected in dialkoxy-PPVs such as MEH-PPV owing to an efficient exciton transfer to the fluorescent porphyrin unit.     

Leprosy patients with lepromatous disease recognize cross-reactive T cell epitopes in the Mycobacterium leprae 10-kD antigen

BACKGROUND: Cough associated with gastroesophageal reflux (GER) may originate in extrathoracic airway receptors made hypersensitive by acid-induced mucosal injury. OBJECTIVE: We investigated the role of laryngeal disease and dysfunction in the pathogenesis of GER-associated cough in nonasthmatic patients. METHODS: Seven patients with GER-associated cough were compared with 7 patients with GER but no cough. The patients underwent fiberoptic endoscopy for assessment of laryngitis and esophagitis (expressed by scores); esophageal manometry; 24-hour pH monitoring; lung function tests; and histamine inhalation challenge with assessment of bronchial threshold (concentration provoking 10% fall in FEV1 [PC10]), extrathoracic airway threshold (concentration provoking 25% fall in the maximal midinspiratory flow [PC25MIF50]), and cough threshold (concentration provoking 5 or more coughs PCcough). The patients were reevaluated after 3 months of medical treatment for GER. RESULTS: Patients with cough, compared with those without cough, had significantly higher laryngitis scores (P = .002), lower esophageal sphincter pressures, longer time with pH below 4 (P = .003), greater number of episodes of reflux longer than 5 minutes (P = .016), longer esophageal clearance time (P = .048), and significantly lower PC25MIF50 (P = .005) and PCcough (P = .008) values. Laryngitis score was significantly inversely related to either PCcough (P < .001) or PC25MIF50 (P <.01) but not to PC10. Laryngitis score, PC25MIF50, and PCcough were all closely related to GER severity. After GER treatment, laryngitis, PC25MIF50, and PCcough were all significantly improved. CONCLUSIONS: These findings suggest that GER-associated cough is strongly associated with laryngeal disease and dysfunction consequent to acid reflux injury in nonasthmatic patients.     

Removal and recovery of nickel(II) from aqueous solution by loofa sponge-immobilized biomass of Chlorella sorokiniana: characterization studies

The biosorption process for the removal of nickel(II) by loofa sponge-immobilized biomass of Chlorella sorokiniana (LIBCS), a newly developed immobilized biosorbent, was characterized. Effects of environmental factors on metal uptake capacity of LIBCS were studied and compared with free biomass of C. sorokiniana (FBCS). Nickel(II) removal by LIBCS was found to be influenced by pH of the solution, initial metal concentration, and biomass concentration. The biosorption of nickel(II) ions by both LIBCS and FBCS increased as the initial concentration of nickel(II) ions increased in the medium. No loss to biosorption capacity of LIBCS for nickel(II) was found due to the presence of loofa sponge, indeed as compared to FBCS an increase of 25.3% was noted in the biosorption capacity of LIBCS. Maximum biosorption capacities for FBCS and LIBCS were found as 48.08 and 60.38 mg nickel(II)/g, respectively, whereas the amount of nickel(II) ions adsorbed on the plain loofa sponge was 6.1mg/g. During these biosorption studies, LIBCS exhibited excellent physical and chemical stability without any significant release/loss of microalgal biomass from loofa sponge matrix. The kinetics of nickel(II) removal was extremely fast reaching at equilibrium in about 15 min for LIBCS and 20 min for FBCS. The biosorption equilibrium was well described by the Langmuir and Freundlich adsorption isotherms. The biosorption capacities were found to be solution pH dependent and the maximum adsorption was found at a solution pH 4-5. The LIBCS could be regenerated using 75 mM HCl, with up to 98% recovery. The LIBCS were shown to be robust and stable with little decrease in the nickel(II) uptake capacity when used in consecutive seven biosorption-desorption cycles. Continuous removal of nickel(II) from electroplating effluent by LIBCS packed in fixed bed column bioreactor confirm the possibility of developing a biological treatment process for the removal of toxic metals from authentic wastewater.     

Robust forecasting of mortality and fertility rates: A functional data approach

A new method is proposed for forecasting age-specific mortality and fertility rates observed over time. This approach allows for smooth functions of age, is robust for outlying years due to wars and epidemics, and provides a modelling framework that is easily adapted to allow for constraints and other information. Ideas from functional data analysis, nonparametric smoothing and robust statistics are combined to form a methodology that is widely applicable to any functional time series data observed discretely and possibly with error. The model is a generalization of the Lee-Carter (LC) model commonly used in mortality and fertility forecasting. The methodology is applied to French mortality data and Australian fertility data, and the forecasts obtained are shown to be superior to those from the LC method and several of its variants.     

Microstructure and characterization of phases in TIG welded joints of Zircaloy-4 and stainless steel 304L

Tungsten inert gas (TIG) welded joints between Zircaloy-4 and stainless steel 304L have been studied by scanning electron microscope (SEM) having energy dispersive system (EDS) as an attachment. Intermetallic compound Zr(Cr, Fe)₂ and Zr₂Fe–Zr₂Ni eutectic phase have been observed in the molten zone. The surface area occupied by intermetallic compound Zr(Cr, Fe)₂ is about twice compared to Zr₂Fe–Zr₂Ni eutectic phase. The shape of the intermetallic compound is rod like. The phases were also identified by using X-ray diffraction (XRD) technique. EDS and XRD results are quite in agreement.     

Synthesis of multi-walled carbon nanotube/silica nanoparticle/polystyrene microsphere/polyaniline based hybrids for EMI shielding application

Novel polystyrene microsphere (PSMS)-based PSMS/Si and polystyrene/silica nanoparticle/multi-walled carbon nanotube (PS/Si/MWCNT) nanocomposite has been prepared using in situ sol-gel and chemical amalgamation methods. Aniline monomer was introduced by in situ route to form PSMS/PANI, PSMS/PANI/Si and PSMS/PANI/Si/MWCNT nanocomposite. FESEM of nanocomposite indicated core-shell spherical and tubular morphology. Glass transition temperature (T_g) and maximum decomposition temperature (T_max) of PSMS/PANI/Si/MWCNT nanocomposite were found as 295°C and 524°C, respectively, which were higher than the PSMS/PANI (T_g = 245°C; T_max = 387°C) and PSMS/PANI/Si (T_g = 257°C; T_max = 388°C) nanocomposite. For nanocomposite dispersion, tetrahydrofuran was studied as fine solvent. XRD depicted amorphous nature of PSMS/Si and PSMS/PANI/Si; however MWCNT reduced amorphous character of PSMS/PANI/Si/MWCNT. Electromagnetic interference (EMI) shielding effectiveness improved from 0.1 dB (PSMS) to 12.3 dB (PSMS/PANI/Si) to 24.5 dB (PSMS/PANI/Si/MWCNT). The increase in EMI shielding effectiveness was also observed with variation in log of conductivity from ?14 mho m^?1 (PSMA) to 1.17 mho m^?1 (PSMS/PANI/Si/MWCNT).     

A decision support framework for metrics selection in goal-based measurement programs: GQM-DSFMS

Software organizations face challenges in managing and sustaining their measurement programs over time. The complexity of measurement programs increase with exploding number of goals and metrics to collect. At the same time, organizations usually have limited budget and resources for metrics collection. It has been recognized for quite a while that there is the need for prioritizing goals, which then ought to drive the selection of metrics. On the other hand, the dynamic nature of the organizations requires measurement programs to adapt to the changes in the stakeholders, their goals, information needs and priorities. Therefore, it is crucial for organizations to use structured approaches that provide transparency, traceability and guidance in choosing an optimum set of metrics that would address the highest priority information needs considering limited resources. This paper proposes a decision support framework for metrics selection (DSFMS) which is built upon the widely used Goal Question Metric (GQM) approach. The core of the framework includes an iterative goal-based metrics selection process incorporating decision making mechanisms in metrics selection, a pre-defined Attributes/Metrics Repository, and a Traceability Model among GQM elements. We also discuss alternative prioritization and optimization techniques for organizations to tailor the framework according to their needs. The evaluation of the GQM-DSFMS framework was done through a case study in a CMMI Level 3 software company.     

Surface modification of mild steel with Boron Carbide reinforcement by electron beam melting

We investigated the effect of surface hardening and micro-structural modifications in Mild steel (MS) with the addition of Boron Carbide, melted by thermionic electron beam. Boron Carbide in the form of powder was added by making grooves in MS samples to trap the molten solution for interaction with solid particles. These samples were irradiated by 10 KeV electron beam with variable beam current (50-100 mA). XRD confirmed the addition of Boron Carbide in the matrix and SEM indicated micro-structural changes introduced by the electron beam. Micro-structural modification further revealed that ferrites have been transformed into dendrites and pearlites have been refined as a result of re-solidified melt. This significantly has enhanced the surface hardness greater than 6-times compared to as received Mild steal.     

Performance of directly modulated DFB lasers in 10-Gb/s ASK, FSK,and DPSK lightwave systems

A comparison is presented of the performance of amplitude-shift-keying (ASK), frequency-shift keying (FSK), and differential-phase-shift-keying (DPSK) lightwave systems which operate at 10 Gb/s with directly modulated 1550-nm distributed feedback (DFB) laser transmitters and conventional 1310-nm dispersion-optimized fiber. Computer modeling techniques were used to accurately simulate the amplitude modulation response and the frequency modulation response of DBF lasers. The system performance is evaluated from simulated eye patterns for both direct and heterodyne detection. With the narrow-optical spectral widths of these signal formats, fiber chromatic dispersion limits up to 70 km were obtained for transmission at 1550-nm using conventional 1310-nm optimized fiber     

Effects of gain ripples in semiconductor optical amplifiers on veryhigh speed lightwave systems

An experimental and theoretical study of the effects of gain ripples in semiconductor optical amplifiers on lightwave systems at data rates in excess of 10 Gb/s is discussed. Significant system degradations, or even complete eye closure, occurred in an 11 Gb/s system due to the effect of large amplifier gain variations on the signals from a directly modulated distributed-feedback laser