Electrochemical study of zinc selenide thin films prepared for photovoltaic applications

Polycrystalline thin films of cubic zinc selenide semiconductor have been electrochemically deposited on conducting substrates of indium tin oxide, ITO glass. Initial investigation with voltammetry was done and the influence of deposition potential and of bath temperature on the films crystallinity is discussed. At room temperature, amorphous films were obtained and at elevated bath temperatures between 55 oC and 75 oC, films were crystallined. The best deposition voltage obtained was -0.95 V vs. Ag /AgCl while at lower deposition potentials, the films do not form well. Energy Dispersive Analysis and X-Ray spectrum indicate that the films deposited at 65 oC and -0.95 V vs. Ag/AgCl have nearly stoichiometric Zn: Se ratio. Energy band gap and refractive index are in agreement with reported results

Multi-wavelength fiber laser with erbium doped zirconia fiber and semiconductor optical amplifier

Multi-wavelength hybrid fiber lasers are demonstrated in both ring and linear cavities using a fabricated Erbium-doped Zirconia fiber (EDZF) and semiconductor optical amplifier (SOA) as gain media. In both configurations, the a fiber loop mirror, which is constructed using a 3 m long polarization maintaining fiber (PMF) and a polarization insensitive 3dB coupler is used as a comb filter for the fiber laser. In the ring cavity, 10 simultaneous lines with peak power above -26 dBm is obtained at 1550 nm region. This is an improvement compared to the linear cavity configuration which has only 5 simultaneous lines observed from wavelength 1556.1 nm to 1563.0 nm with the peak power above -40 dBm. Both hybrid lasers has a constant line spacing of 1.7 nm, which is suitable for wavelength division multiplexing and sensing applications and shows a stable operation at room temperature

Characterisation of plasticised PVDF–HFP polymer electrolytes

This study focuses on the preparation and characterisation of sodium ion conducting polymer electrolytes. Poly(vinylidenefluoride-co-hexafluoropropylene) has been used as the host matrix and hydrated sodium sulphide (Na2S.9H2O) salt as the source of charge carriers in the polymer electrolyte system. To the highest conducting polymer–salt electrolyte, different concentrations of equal weight of propylene carbonate and diethyl carbonate mixture have been added, and the electrolytes have been characterised by X-ray diffraction, Fourier transform infrared spectrometry, scanning electron microscopy and electrochemical impedance spectroscopy. The room temperature ionic conductivity of 1?3461024 S cm21 for the unplasticised electrolyte with a composition of 65 wt-% poly(vinylidenefluoride-co-hexafluoropropylene)–35 wt-%Na2S increased to 3?4961024 S cm21 when 30 wt-% propylene carbonate/diethyl carbonate (w/w51) plasticisers were added

Causative failure factors of communications management in mixed-use development projects in Malaysia

Construction delay has been a persistent challenge for the Malaysian construction industry. This has resulted in many issues, including public complaints, government loss of reputation and income and a decline in the gross domestic product output of the industry. Furthermore, the construction industry is a complex business with several stakeholders continually sharing information. Hence, ensuring project success has to be the utmost important task of a project manager. Often the construction industry is marred by high cases of delays, overruns, poor quality, health and safety issues, emissions and sustainability issues as a result of ineffective communication practices. Therefore, this paper aims to examine causative failure factors of communications management in mixed-use development projects in Malaysia. Based on the literature review, 11 factors and 44 items were identified. These factors and items were evaluated by 141 respondents from the Malaysian construction industry. Data analysis was done using SPSS 23.0. This study found that the most critical causative failure factor is team meeting discussions. The respondents believe that there is lack of stakeholder cooperation due to poor representation during the discussions, which also reflects the inadequacy of mutual respect, confidence and trust among stakeholders. As a recommendation, frequent team meeting discussions provide a platform for effective information exchange, thus help to reduce mixed-use project failures in Malaysia

Second and third-order nonlinear optical behavior of natural pigment: chlorophyll and crocin

To provide an insight into the microscopic second and third-order nonlinear optical (NLO) behavior of chlorophyll a and crocin, we have computed the electric dipole moments (μ), dispersion-free first hyperpolarizabilities (β), frequency-dependent first and second (γ) hyperpolarizabilities at 1064 nm wavelength area using time-dependent Hartree-Fock (TDHF) method. According to ab-initio calculation results, the examined compounds exhibit first and second hyperpolarizabilities with non-zero values, implying second and third-order NLO phenomena

Computational studies on linear, second and third-order nonlinear optical properties of novel styrylquinolinium dyes

The electric dipole moments (μ), static dipole polarizabilities (α) and first hyperpolarizabilities (β) of styrylquinolinium dyes, D8 and D21, have been computed by density functional theory (DFT). The one-photon absorption (OPA) characterizations have been investigated using UV–vis spectroscopy and further interpreted using computational chemistry. The time-dependent Hartree–Fock (TDHF) method has been used to describe the dynamic dipole polarizabilities, dynamic second-order and also static and dynamic third-order nonlinear optical (NLO) properties. D8–D21 have rather high β and second hyperpolarizabilities (γ). The highest occupied molecular orbitals (HOMO), the lowest unoccupied molecular orbitals (LUMO) and the HOMO–LUMO band gaps for D8–D21 have been evaluated by DFT