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Abstract: The nano-structure BaTiO3 (BT) powder doped with different concentrations of Nd3+ ions were annealed at 750°C for 1h to form nano-structure tetragonal phase of BT powder. The structure properties studied using XRD and FTIR methods. Sensitized up-conversion luminescence observed under excitation of 808nm diode laser, suggesting that the Nd3+ ions-doped BT might be an ideal up-conversion material for infrared excitation. The influence of increasing the concentration of the Nd3+ ions on the luminescence intensity investigated using laser diode. The up-conversion mechanisms in the doped system will be discussed by analyzing the energy level structures of the Nd3+ ions. [Copyright &y& Elsevier]

Abstract: Effects of Sm3+/Yb3+ co-doping on Raman scattering, IR absorption, temperature dependence of the Raman spectra up to 210°C and the structure of two glass systems of the composition (80TeO2–10GeO2–8K2O–2Sm2O3/Yb2O3) is discussed. It was found that the addition of Yb3+ to the glass very strongly enhances the intensities of the antistokes’ Raman bands at 155, 375, 557 and 828cm−1 and quenches both the intensities of the stokes’ vibration modes of the TeO4 units in the range of 120–770cm−1 and the intensities of the OH− stretching vibration modes in the range of 2600–3300cm−1. Sm2O3/Yb2O3 rare earth co-doping has a great influence on removing and/or changing the nature of the OH− groups. The appearance and splitting of the stretching vibration modes of the OH− groups at lower frequencies (2770, 2970cm−1) for the Sm+3 singly doped glass sample, compared to the band at ∼3200cm−1 for the Sm3+/Yb3+ co-doped glass sample, suggested that the OH− groups are more strongly bonded and incorporated with the glass matrix for the singly doped glass. Heating the sample up continuously weakens the hydrogen bonding of the OH− groups to the glass matrix leading to creation of NBO and breakdown of the connectivity of the OH− groups to the TeO4, TeO3+1 and TeO3 structural units. Raman bands at 286, 477, 666 and 769cm−1 were assigned to its respective vibrations of Te2O7, TeO4 −4 species, the (Te–O–Te)bending vibrations of the TeO4 triagonal bipyramids (tbps), the axial symmetric stretching vibration modes (Teax–O)s with bridging oxygen BO atoms and to the (Te–O)nbo non-bridging stretching vibration modes of the TeO3+1 and/or TeO3 pyramids. [Copyright &y& Elsevier]

The structure of [80TeO2 + (20– x)MoO + xNd2O3] glasses, with x = 0, 4, 6, 10 and 12 mol%, is studied in this work. Raman scattering in the spectral range (−2000 to 3500 cm−1) and IR absorption spectra have been measured for crystalline TeO2 and glasses, and their assignments were discussed and compared. Many vibrational modes were found active in both Raman and IR and their assignments for crystalline TeO2 and for the glasses were discussed in relation to the tetragonal structure of crystalline α -TeO2. Nd2O3 was found to completely eliminate diffuse scattering and enhance the Raman scattering intensity. Anti-stokes Raman bands in the range −1460 cm− 1 to −1975 cm− 1 were observed for both (30Li2O + 70B2O3+ xNd2O3) glasses and [80TeO2 + (20− x)MoO + xNd2O3] glasses and were attributed to some emission processes due to the doping of the glasses with Nd2O3. [ABSTRACT FROM AUTHOR]

A time-resolved Fourier transform IR spectrometer is used to measure the emitted spectra of the fragments resulting from the photodissociation of 3S Rydberg state acetone by a 193 nm excimer laser at different delay times between the FTIR and the laser. Two vibrational bands are detected. The first band, a single peak in the range of 3200–2750 cm-1, is assigned to be the CH of the methyl radicals, is unresolved. The second is a resolved double peak band in the range of 2250–1950 cm-1 is assigned to be the P and R branches of the CO molecule. The emitted spectra of the CO molecule and the methyl radicals are measured at different delay times from 1 to 50 μs. The integrated intensity of the emitted spectra of CO was found to increase with delay times up to 50 μs, while that of the methyl radicals showed the opposite behaviour. Plotting the relationship between the laser power and the integrated intensity of the CO spectrum yielded a straight line with a gradient ∼1. this may indicate that the process is a single-photon reaction. [Copyright &y& Elsevier]

We report on an examination of pulse timing stability of a home built Erbium Doped Fiber Laser (EDFL) passively mode locked via nonlinear polarization rotation by inserting semiconductor saturable absorber mirror (SESAM) in laser cavity. A very low root mean square (RMS) timing jitter (less than 27 fsec) and faster self-starting mode locking have been established. In order to get clear, low noise signal for time resolving measurements, synchronization of EDFL laser with an external high precision electronic oscillator have been established. Subsequently, it is synchronized and optically cross-correlated with a Ti:Sapphire laser source (Micra). The measured relative timing jitter was found to be less than 65 fsec. In this way, the two, well synchronized Ti:Sapphire and EDFL laser pulses prove to be a powerful tool for time resolving measurements. [ABSTRACT FROM AUTHOR]

Road traffic deaths and serious injuries are a global public health issue, particularly in the Arab region, where the mortality rate from road crashes surpasses the global average and is more than three times higher than the European region's average. In this regard, an Arab Integrated Road Safety Observatory is being developed to help Arab countries execute evidence-based policies, strategies, and action plans, as well as meet the global targets of the second decade of action (2021 2030). Because numerous experiences exist at the worldwide level, the current paper aims to serve as a platform and reference for the Arab Observatory's development of an integrated Regional Road Safety Information System (RRSIS). In this regard, current RRSISs in various parts of the world were extensively examined and compared using literature and semi-structured interviews with international specialists. Six RRSIS from regional observatories or RRSISs with regional data sets were included in the benchmarking. As a result, various parallels and contrasts were found: a) at the technical level, each RRSIS has its own areas of interest (data, policy, or both), scope (aggregated or disaggregated data), and thus different sets of collected variables and values; b) at the organizational level, several similarities are identified, particularly with regard to the organizational structure; c) at the financial level, multiple differences are revealed, either for financial resources or scale expenditure. On the one hand, benchmarking is required to learn from prior experiences and current models as a source of inspiration. On the other hand, harmonization and coordination assure and guarantee consistency, integrity, and communication between the future Arab RRSIS and the existing regional RRSIS [ABSTRACT FROM AUTHOR]

Lead sulfide (PbS) nano-structured film has been grown on quartz substrates by the PLD technique. The deposited films were characterized by X-ray diffraction (XRD), selected area electron diffraction (SAED), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Formation of cubic phase of PbS nanocrystals is proven. The absorption and emission spectra were measured for different thicknesses of the films. I- V characteristics and photoconductivity of the deposited film were also measured. The results indicate an efficient performance of the deposited films as an optical detector. [ABSTRACT FROM AUTHOR]

Silica nanoparticles (SiO2 NPs) are active in the photocatalytic degradation of methyl red dye (MR). SiO2 NPs and SiO2 NPs that have been doped with either silver (Ag NPs) and/or gold nanoparticles (Au NPs) were prepared. The particle size and morphology of the catalysts were assessed by transmission electron microscopy (TEM) imaging. The rate of photocatalytic degradation of MR was found to increase from SiO2 NPs, SiO2 NPs coated with both Au NPs and Ag NPs, SiO2 NPs coated with Ag NPs, SiO2 NPs coated with Au NPs, Ag+-doped SiO2 NPs to Au3+-doped SiO2 NPs. [ABSTRACT FROM AUTHOR]

Abstract: Pseudomonas aeruginosa were used for extra-cellular biosynthesis of gold nanoparticles (Au NPs). Consequently, Au NPs were formed due to reduction of gold ion by bacterial cell supernatant of P. aeruginosa ATCC 90271, P. aeruginosa (2) and P. aeruginosa (1). The UV–vis and fluorescence spectra of the bacterial as well as chemical prepared Au NPs were recorded. Transmission electron microscopy (TEM) micrograph showed the formation of well-dispersed gold nanoparticles in the range of 15–30nm. The process of reduction being extra-cellular and may lead to the development of an easy bioprocess for synthesis of Au NPs. [Copyright &y& Elsevier]

Nanocrystalline CoFe2O4 ferrite samples have been synthesized by co precipitation method. The prepared samples were irradiated by second harmonic diode pumped Nd:YAG laser with average power 150 m W of wavelength 532 nm for 5 min at a distance of 30 cm. The prepared samples were characterized to study the different properties of samples. X-ray diffraction analysis reveals a single-phase cubic spinel structure before/after irradiation. The broadening of the peaks indicates a reduction in crystallite size with ultra-fine nature for irradiated samples. EDAX analysis shows that the predictable composition present in the samples agrees well with the nominal compositions. Nd:YAG laser irradiation shows remarkable changes on structural as well as magnetic properties. The decreasing of the coercivity for the irradiated samples suggests that laser-irradiation and roughness can be used to tune the magnetic hardness of the ferrite materials. [ABSTRACT FROM AUTHOR]

Abstract La 0.8 Sr 0.2 MnO 3 (LSM) polycrystalline powder was synthesized using hydrothermal method at 900 °C. High Resolution Transmission Electron Microscope (HR-TEM) showed that the particles were uniform with average particle size of 657 nm. X-ray Diffraction (XRD) and lattice fringes indicated rhombohedral structure of LSM particles. Thin LSM films were successfully grown on cleaned Si (100) substrate by pulsed laser deposition (PLD). Annealing of LSM films in air affected structure, morphology and electrical properties that films where crystallization of the LSM films was started at 600 °C and enhanced by further annealing as indicated by XRD. Field Emission Scanning Electron Microscope (FESEM) revealed that the grain size increases by increasing annealing temperature and at temperature of 1000 °C cracks were seen. Average roughness and root mean square roughness decreased with further annealing (up to 800 °C) then increased at 1000 °C that were verified by atomic force microscope (AFM). Moreover, Raman scattering was enhanced and all major bands were revealed at 800 °C. Resistivity of LSM films decreases with increasing temperature (from 25 °C to 200 °C) and all films underwent a semiconductor behavior in the most of applied temperatures. The lowest resistivity of LSM films was reached at annealing temperature of 800 °C with low activation energy value (E a) of about 0.1 eV. Graphical abstract Unlabelled Image [ABSTRACT FROM AUTHOR]

Abstract The irradiation of rumen fluid (RF) with laser source was hypothesized to enhance the anaerobic process and accelerate the manure digestion, which increases the biogas and methane production. The photobiostimulating effects of laser irradiation on biogas and methane production were investigated by irradiating the RF for 0.5, 1 and 2 h with 532 nm laser source compared with 1 h incandescent light, non-irradiated RF and the control. The highest significant values of the biogas and methane production were found to be 583 ml Biogas g−1 VS and 367.9 ml CH 4 g−1 VS when RF was irradiated for 0.5 h with 532 nm laser source (p < 0.05) compared with the other irradiation times with laser, incandescent light source, non-irradiated RF, and the control which yielded only 357 ml Biogas g−1 VS and 196 ml CH 4 g−1 VS, respectively. Moreover, the biogas and methane production rates were found to be inversely proportional with the irradiation time using laser source. The results showed that the lag phase was reduced from 4 days to 1 day. Additionally, the time to achieve the highest biogas production (peak) was reduced from day 28 to day 16 of the Hydraulic Retention Time (HRT) compared with the control. Highlights • Photobiostimulation using laser source enhances the activity of microorganisms. • Irradiation of bacteria with laser source accelerates the anaerobic digestion. • Biogas and methane production are inversely proportional to laser exposure time. • Irradiation of bacteria with laser source increases biogas and methane production. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) were hypothesized to enhance the anaerobic process and to accelerate the slurry digestion, which increases the biogas and methane production. The effects of NPs on biogas and methane production were investigated using a specially designed batch anaerobic system. For this purpose, a series of 2 L biodigesters were manufactured and implemented to study the effects of Cobalt (Co) and Nickel (Ni) nanoparticles with different concentrations on biogas and methane production. The best results of NPs additives were determined based on the statistical analysis (Least Significant Difference using M-Stat) of biogas and methane production, which were 1 mg/L Co NPs and 2 mg/L Ni NPs ( p < 0.05). These NPs additives delivered the highest biogas and methane yields in comparison with their other concentrations (0.5, 1, and 2 mg/L), their salts (CoCl 2 , and NiCl 2 ) and the control. Furthermore, the addition of 1 mg/L Co NPs and 2 mg/L Ni NPs significantly increased the biogas volume ( p < 0.05) by 1.64 and 1.74 times the biogas volume produced by the control, respectively. Moreover, the aforementioned additives significantly increased the methane volume ( p < 0.05) by 1.86 and 2.01 times the methane volume produced by the control, respectively. The highest specific biogas and methane production were attained with 2 mg/L Ni NPs ( p < 0.05), and were 614.5 ml Biogas g −1 VS and 361.6 ml CH 4 g −1 VS, respectively compared with the control which yielded only 352.6 ml Biogas g −1 VS and 179.6 ml CH 4 g −1 VS. [ABSTRACT FROM AUTHOR]

In this study, nanoparticles (NPs) were hypothesized to enhance the anaerobic process and to accelerate the slurry digestion, which increases the biogas and methane production. The effects of NPs on biogas and methane production were investigated using a specially designed batch anaerobic system. For this purpose, a series of 2 L biodigesters were manufactured and implemented to study the effects of the nanoparticles of Iron (Fe) and Iron Oxide (Fe 3 O 4 ) with different concentrations on biogas and methane production. The best results of NPs additives were selected based on the statistical analysis (Least Significant Difference using M-Stat) of biogas and methane production, which were 20 mg/L Fe NPs and 20 mg/L Fe 3 O 4 magnetic NPs (p < 0.05). The aforementioned NPs additives delivered the highest biogas and methane yields in comparison with their other concentrations (5, 10 and 20 mg/L), their salt (FeCl 3 ) and the control. Furthermore, the addition of 20 mg/L Fe NPs and 20 mg/L Fe 3 O 4 magnetic NPs significantly increased the biogas volume (p < 0.05) by 1.45 and 1.66 times the biogas volume produced by the control, respectively. Moreover, the aforementioned additives significantly increased the methane volume (p < 0.05) by 1.59 and 1.96 times the methane volume produced by the control, respectively. The highest specific biogas and methane production were attained with 20 mg/L Fe 3 O 4 magnetic NPs, and were 584 ml Biogas g −1 VS and 351.8 ml CH 4 g −1 VS, respectively compared with the control which yielded only 352.6 ml Biogas g −1 VS and 179.6 ml CH 4 g −1 VS. [ABSTRACT FROM AUTHOR]

Nanoparticles (NPs) of trace metals such as Co, Ni, Fe and Fe 3 O 4 were implemented in this study to compare their effects on biogas and methane production from anaerobic digestion of livestock manure. The most effective concentrations of NPs additives were determined based on our previous studies, and were 1 mg/L Co NPs, 2 mg/L Ni NPs, 20 mg/L Fe NPs and 20 mg/L Fe 3 O 4 NPs. These concentrations of NPs additives were further investigated and compared to each other in this study and were found to significantly (p < 0.05) increase the biogas yield by 1.7, 1.8, 1.5 and 1.7 times in comparison with control, respectively. The methane yield significantly (p < 0.05) increased by 2, 2.17, 1.67 and 2.16 times the methane volume of the control, respectively. The results of this study showed that the Ni NPs yielded the highest biogas and methane production compared to Co, Fe and Fe 3 O 4 NPs. [ABSTRACT FROM AUTHOR]

Au and Au–CdSe nanoparticles (NPs) have been synthesized by organometallic pyrolysis method. Nano-crystals (NCs) structure was confirmed using high resolution transmission electron microscope (HRTEM) and X-ray diffraction (XRD). Nonlinear optical absorption is investigated by Z -scan technique using nanosecond laser pulses of second harmonic Nd:YAG. Intensity-dependence of nonlinear absorption on both nano-size and concentrations is reported. These are interesting findings which can be used to fabricate optical limiting and optical switching devices from NPs and hybrid systems. [ABSTRACT FROM AUTHOR]

• Highly efficient TE pass polarizer based on dual D-shaped PCF is reported. • D-shaped layers are coated by gold films to enhance the filtering characteristics. • The SP modes are strongly coupled to the TM core mode with high confinement loss. • An insertion loss of −0.39 and −0.57 dB/cm are achieved at λ = 1300 nm and 1550 nm. • Large bandwidth from λ = 1.2 µm to λ = 1.6 µm is obtained with crosstalk < −21 dB. In this work, a highly efficient transverse-electric (TE) pass polarizer based on dual D-shaped photonic crystal fiber (PCF) is designed and analyzed. The PCF birefringence between the two polarized modes is efficiently controlled by adjusting the core region. Additionally, the dual D-shaped layers are coated by gold films to enhance the filtering characteristics. Therefore, the surface plasmon (SP) modes at the metal/dielectric interface are strongly coupled to the quasi-transverse-magnetic (TM) core mode with high confinement loss in comparable to the conventional D-shaped PCF. However, no coupling occurs with the quasi-TE core mode. Thus, a TE-pass polarizer is realized with an insertion loss (IL) of −0.39 dB/cm and −0.57 dB/cm at the two-telecommunication wavelengths of 1300 nm and 1550 nm, respectively. Moreover, the reported device has a wide operation bandwidth that extends from λ = 1.2 µm to λ = 1.6 µm where the crosstalk (CT) is less than −21 dB. [ABSTRACT FROM AUTHOR]