Search

To obtain good economic and environmental benefits, LaMgNi3.6M0.4 (M = Al, Mn, Ni, Co, Cu) alloys are investigated for the hydrogen storage. The absorption data of hydrogen in the tested alloys are measured experimentally at 373 K. The hydrogen absorption isotherms are analyzed using three models derived from statistical physics formalism. The adequate model permits to discover significant details about the absorption phenomenon via determining the density of the interstitial sites (Dm), the number of hydrogen atoms per site (n) and the energetic parameter ΔE. The results indicate that multi-atomic (n > 1) and multi-linking (n

New homologues series of liquid crystalline materials namely, (E)-3-methoxy-4-[(p-tolylimino)methyl]phenyl 4-alkloxybenzoates (I-n), were designed and evaluated for their mesomorphic and optical behavior. The prepared series constitutes three members that differ from each other by the terminally attached alkoxy chain group, these vary between 6 and 12 carbons. A laterally OCH3 group is incorporated into the central benzene ring in meta position with respect to the ester moiety. Mesomorphic characterizations of the prepared derivatives are conducted using differential scanning-calorimetry (DSC), polarized optical-microscopy (POM). Molecular structures were elucidated by elemental analyses and NMR spectroscopy. DSC and POM investigations revealed that all the synthesized derivatives are purely nematogenic exhibiting only nematic (N) mesophase, except for the longest chain derivative (I-12) that is dimorphic possesses smectic A and N phases. Moreover, all members of the group have a wide mesomorphic range with high thermal nematic stability. A comparative study was established between the present derivative (I-6) and their previously prepared isomer. The results indicated that the location exchange of the polar compact group (CH3) influences the N mesophase stability and range. The electrical measurements revealed that all synthesized series I-n show Ohmic behaviors with effective electric resistances in the GΩ range. Under white light illumination, the effective electric conductivity for the compound I-8 is five times that obtained in dark conditions. This derivative also showed two direct optical band gaps in the UV and visible light range. In addition, I-6 has band energy gaps of values 1.07 and 2.79 eV, which are suitable for solar energy applications.

New mesomorphic series, 4-hexadecyloxy phenyl-imino-4′-(3-methoxyphenyl)-4″-alkoxybenzoates (An), were prepared and investigated with different thermal and mesomorphic techniques. The synthesized homologous series constitutes four members that differ from each other in the terminal length of flexible chain (n) attached to phenyl ester moiety, which varies between n = 6, 8, 10, and 12 carbons. A lateral CH3O group is attached to the central benzene ring in the meta position with respect to the ester moiety. Molecular structures of all newly prepared homologues were elucidated via FT-IR, 1H and 13C NMR spectroscopy. Mesomorphic and thermal properties were examined by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and the mesophases identified by polarized optical microscopy (POM). DSC and POM examinations revealed that all members of the present series (An) exhibit a purely enantiotropic nematic (N) phase. Comparative evaluations and binary phase diagrams were established between the present homologues and their corresponding shorter one (Bn). The examination revealed that, the length of the flexible alkoxy chain incorporated into the phenylimino moiety is highly effective on the temperature range and stability of the mesophase observed. With respect to the binary mixtures An/Bn, the exhibited N phase showed to cover the whole composition range with eutectic behavior.

Pesticide residues are harmful to the environment and human and animal health even at low levels because of long-term bioaccumulation. In this study, photolysis was applied to treat three representative water samples: aqueous atrazine and dimethoate solutions as target pesticides, as well as wastewater and agriculture wastewater containing pesticide residue. It was performed using ultraviolet (UV) irradiation at two wavelengths (254 and 306 nm) with exposure times ranging from 2 to 12 h in the presence and absence of a photocatalyst to identify the optimal degradation conditions. Extraction and analyzation process were performed by the Quick Easy Cheap Effective Rugged Safe (QuEChERS) methods and gas chromatography–tandem mass spectrometry with triple quadrupole detector (GC–MSMS/TQD), respectively. Photodegradation increased with an increase in exposure time and the TiO2 catalyst was beneficial for degradation. Both selected irradiation wavelengths were effective, although the wavelength of λ = 306 nm was the most efficient.

One of the most serious environmental concerns worldwide is the consequences of industrial wastes and agricultural usage leading to pesticide residues in water. At present, a wide range of pesticides are used directly to control pests and diseases. However, environmental damage is expected even at their low concentration because they are sustained a long time in nature, which has a negative impact on human health. In this study, photolysis and photocatalysis of the pesticides dieldrin and deltamethrin were tested at two UV wavelengths (254 and 306 nm) and in different test media (distilled water, wastewater, and agricultural wastewater) to examine their ability to eliminate pesticides. TiO2 (0.001 g/10 mL) was used as a catalyst for each treatment. The purpose was to determine the influence of UV wavelength, exposure time, and catalyst addition on the pesticide decomposition processes in different water types. Water was loaded with the tested pesticides (2000 µg) for 12 h under UV irradiation, and the pesticide concentrations were measured at 2 h intervals after UV irradiation. The results showed a clear effect of UV light on the pesticides photodegradations that was both a wavelength- and time-dependent effect. Photolysis was more effective at λ = 306 nm than at λ = 254 nm. Furthermore, TiO2 addition (0.001 g/10 mL) increased the degradation at both tested wavelengths and hence could be considered a potential catalyst for both pesticide degradations. Deltamethrin was more sensitive to UV light than dieldrin under all conditions.

A quaternary glass system was fabricated via the melting quenching method. The mentioned glass system consists of five samples described by the chemical composition 50B2O3 + 30BaF2 + (20-x)Li2O + xAg2O, 0.0

The purpose of this investigation is to study the physical, structural and optical characteristics of a newly fabricated SrO2 doped lithium bismuth borate glass system. The current glass system was fabricated according to the chemical formula 50B2O3 + 25Bi2O3 + (25-x) Li2O + xSrO2, utilizing the solid state- conventional method. It was noticed that The glass density increased from 4.821 to 5.952 g cm−3 whilst the molar volume was decreasing in the range from 32.93 to 30.44 cm3 mol−1 with increase the SrO2 insertion from 0 (BBLSr0 glasses) to 25 (BBLSr25) respectively. The structure of the fabricated glasses was inspected utilizing X-ray diffraction method which clarified that the insertion of SrO2 didn’t affect the amorphous nature of the tested samples. Furthermore, the UV–vis absorption spectrum was utilized to study the UV absorption characteristics for the fabricated glasses. The UV–vis absorption spectrum showed that the absorption and transition bands increase with insertion of the SrO2 contents. Based on the UV/Vis data, several important optical features were calculated like the energy gap (Eg), Urbach energy (Eu), oscillator energy (Eo) and energy of distribution (Ed). Increasing the SrO2 substitution ratio led to increase the optical properties where the refractive index was found to increase from 3.056 to 5.710.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The broadband visible photoluminescence (PL) from photoelectrochemical etched porous silicon quantum dots (PSi-QDs) containing zinc (Zn) powder is reported. The influence of the Zn content (0, 0.11, 0.17, and 0.25 g) on the structure, morphology, and room-temperature PL characteristics of the PSi-QDs were evaluated. The PSi-QDs were prepared in HF:ethanol solution by electrochemical etching of n-type Si at the optimum etching time and current density with varying masses of added Zn powder. The PL spectra of the as-prepared samples exhibited a broad emission peak in the region of 510–760 nm with the highest intensity at approximately 657 nm. The inclusion of Zn powder in the PSi-QDs was observed to enhance the PL peak intensity by a factor of seven. The improved visible light emitting traits were attributed to the quantum confinement (QC) effect, which widened the energy band gap (1.12–2.5 eV) of the Zn-included PSi-QDs. The present findings may contribute to the development of PSi-QD-based red phosphors and other optoelectronic applications. EDX and FESEM analysis showed that porous silicon etched with Zn mass is mainly composed of oxygen, fluoride, zinc, and silicon.

A series of six tungsten-based bismuth borate glasses with a xWO3- 20 Bi2O3- 20 Na2O2- (60-x) B2O3), 0≤ x ≤ 5 wt% chemical composition were synthesized by using the solid-state conventional method. The structures of the fabricated samples were studied with X-ray diffraction analysis. Optical features such as the energy gap (Eg), Urbach energy (Eu), steepness parameter (S), refractive index (n) and Fermi level energy (EF) were measured for the fabricated glasses with a UV–Vis–NIR spectrophotometer. Furthermore, a Monte Carlo simulation code (MCNP-5) was applied to estimate the gamma ray mass attenuation coefficient (MAC) for the fabricated glasses. The simulated data showed that the insertion of WO3 increases the MACs of the fabricated samples: the highest and lowest MACs were obtained for the W6 and W1 glasses, respectively. Then, the simulated MAC was used to calculate the mean free path (MFP) for all the fabricated glasses. The thinnest MFP was achieved by W6 (increasing from 0.007 to 70,560 between 0.015 and 15 MeV, respectively), while the thickest MFP was achieved by W1 (increasing from 0.0100 to 8.975 between 0.015 and 15 MeV, respectively). Moreover, new Phy-x/PD software was used to calculate MAC, MFP, equivalent atomic number (Zeq) and the exposure and energy absorption buildup factors (EBF and EABF). The simulated and calculated results showed that adding WO3 enhances the shielding properties of the synthesized glass.