Controlling pore structure, e.g. pore diameter, size and distribution of porous silicon (PS) is highly needed for technological applications such as microfluidic operation and filtration in which the pore size and shape can block the entrance of some species or increase its concentration or purity by separation. In the present study, highly doped p-type silicon is utilized to prepare PS with different pore dimensions by electrochemical etching (anodization) process in HF and C2H5OH mixture. The anodization process was performed under various conditions such as different electrolyte types, temperature, and concentrations, etching potential, current density, and etching duration. This research was to further study the influence of electrochemical etching parameters on pore formation kinetics including pore size, layer thickness and mechanistic aspects of silicon etching. The study offers a fundamental understanding of the fabrication process of porous silicon that may be exploited in nanotechnology applications. The present study confirms that the anodization rate increases with increasing the steady-state current at all the presented conditions. It is demonstrated that adjusting the anodizing potential is very important as it determines whether the anodization will lead to PS formation and/or PS dissolution.

Controlling pore structure, e.g. pore diameter, size and distribution of porous silicon (PS) is highly needed for technological applications such as microfluidic operation and filtration in which the pore size and shape can block the entrance of some species or increase its concentration or purity by separation. In the present study, highly doped p-type silicon is utilized to prepare PS with different pore dimensions by electrochemical etching (anodization) process in HF and C2H5OH mixture. The anodization process was performed under various conditions such as different electrolyte types, temperature, and concentrations, etching potential, current density, and etching duration. This research was to further study the influence of electrochemical etching parameters on pore formation kinetics including pore size, layer thickness and mechanistic aspects of silicon etching. The study offers a fundamental understanding of the fabrication process of porous silicon that may be exploited in nanotechnology applications. The present study confirms that the anodization rate increases with increasing the steady-state current at all the presented conditions. It is demonstrated that adjusting the anodizing potential is very important as it determines whether the anodization will lead to PS formation and/or PS dissolution.

Bulk and thin films (150 nm) of As30Te70-xGax (0 ≤ x at.% ≤ 10) are synthesized under vacuum via the melt-quenching and thermal evaporation techniques, respectively. The crystal structure class and formed crystalline phases during the annealing are tested by X-ray diffraction. The influences of both thermal annealing and Ga doping on the electrical properties such as the electric conductivity of As-Te-Ga are investigated and contrasted with published data. For instance; at room temperature, electrical conductivity is improved from 7.7 × 10−4 to 8.04 × 10−3 Ω−1cm−1 at 3 at.% Ga, however, decreased with beyond increase in Ga content. The conductivity of the annealed samples rises as the annealing temperature increases. Furthermore, other basics parameters of the stoichiometric thermally evaporated thin film such as average coordination number, number of ions per electrons, the heat of atomization, cohesive energy, the valence electron, and deviation of stoichiometry are found exactly proportional to the Ga content.

Bulk and thin films (150 nm) of As30Te70-xGax (0 ≤ x at.% ≤ 10) are synthesized under vacuum via the melt-quenching and thermal evaporation techniques, respectively. The crystal structure class and formed crystalline phases during the annealing are tested by X-ray diffraction. The influences of both thermal annealing and Ga doping on the electrical properties such as the electric conductivity of As-Te-Ga are investigated and contrasted with published data. For instance; at room temperature, electrical conductivity is improved from 7.7 × 10−4 to 8.04 × 10−3 Ω−1cm−1 at 3 at.% Ga, however, decreased with beyond increase in Ga content. The conductivity of the annealed samples rises as the annealing temperature increases. Furthermore, other basics parameters of the stoichiometric thermally evaporated thin film such as average coordination number, number of ions per electrons, the heat of atomization, cohesive energy, the valence electron, and deviation of stoichiometry are found exactly proportional to the Ga content.

Bulk and thin films (150 nm) of As30Te70-xGax (0 ≤ x at.% ≤ 10) are synthesized under vacuum via the melt-quenching and thermal evaporation techniques, respectively. The crystal structure class and formed crystalline phases during the annealing are tested by X-ray diffraction. The influences of both thermal annealing and Ga doping on the electrical properties such as the electric conductivity of As-Te-Ga are investigated and contrasted with published data. For instance; at room temperature, electrical conductivity is improved from 7.7 × 10−4 to 8.04 × 10−3 Ω−1cm−1 at 3 at.% Ga, however, decreased with beyond increase in Ga content. The conductivity of the annealed samples rises as the annealing temperature increases. Furthermore, other basics parameters of the stoichiometric thermally evaporated thin film such as average coordination number, number of ions per electrons, the heat of atomization, cohesive energy, the valence electron, and deviation of stoichiometry are found exactly proportional to the Ga content.

Thermoluminescence (TL) properties of La2O3: Dy3+, Li+, and La2O3: Eu3+, Li+, exposed to 5.12 Gy of beta radiation, and recorded at different heating rates 0.5, 1, 2, 3, 4, and 5 °C s−1 (from Molefe et al., paper 2019), were analyzed and the trap parameters were determined in this study. These parameters include the order of kinetics b, the activation energy E (eV), the frequency factor S (s−1), or the pre-exponential factor S″ (s−1), and the initial concentration of trapped electrons no (cm−3). A new non-linear curve fitting technique, based on the general order kinetic equation and the outcomes of Hoogenstraaten’s Method, was established and applied on the TL glow peaks of La2O3: Dy3+, Li+. The fitting technique was evaluated by calculating the R-square and figure of merit (FOM) values. The results revealed that the FOM values are 0.997, which demonstrates an excellent convergence between experimental and fitted curves. A modified technique based on the three-points analysis method was exploited to deconvolute complex TL glow curves of La2O3: Eu3+, Li+, and in turn, to determine the trap parameters the method disclosed that each TL glow curve consists of four peaks. The trap parameters of the individual peaks were numerically determined. The fading, as a function of storage temperature and time, from the TL signals of the investigated materials was predicted and discussed based on the calculated trap parameters. The results support the value of the materials for employment in radiation dosimeter applications with a low fading fraction.

γ-γ correlation functions are mathematical expressions that describe the angular distribution of cascade γ-rays emitted from an atomic nucleus. Cascade transitions may occur in either a two-step deexcitation or through an excitation-deexcitation process of a particular energy level inside the nucleus. In both cases, the nucleus returns to its ground energy state. Spin and parity of the excited state can be determined experimentally using the asymmetry of the angular distribution of the emitted radiation. γ-γ correlation functions are only valid for point-like targets and detectors. In the real experiments, however, neither the target nor the detector is point-like. Thus, misassignment of the spin-parity of energy levels may easily take place if only the analytical equations are considered. Here, we develop a new Monte Carlo simulation method of the γ-γ correlation functions to account for the extended target and detector involved in spin-parity measurements using nuclear resonance fluorescence of nuclei. The proposed simulation tool can handle arbitrary geometries and spin sequences. Additionally, we provide numerical calculations of a parametric study on the influence of the detection geometry on the angular distribution of the emitted γ-rays. Finally, we benchmark our simulation by comparing the simulation-estimated asymmetry ratios with those measured experimentally. The present simulation can be employed as a kernel of an implementation that simulates the nuclear resonance fluorescence process.

γ-γ correlation functions are mathematical expressions that describe the angular distribution of cascade γ-rays emitted from an atomic nucleus. Cascade transitions may occur in either a two-step deexcitation or through an excitation-deexcitation process of a particular energy level inside the nucleus. In both cases, the nucleus returns to its ground energy state. Spin and parity of the excited state can be determined experimentally using the asymmetry of the angular distribution of the emitted radiation. γ-γ correlation functions are only valid for point-like targets and detectors. In the real experiments, however, neither the target nor the detector is point-like. Thus, misassignment of the spin-parity of energy levels may easily take place if only the analytical equations are considered. Here, we develop a new Monte Carlo simulation method of the γ-γ correlation functions to account for the extended target and detector involved in spin-parity measurements using nuclear resonance fluorescence of nuclei. The proposed simulation tool can handle arbitrary geometries and spin sequences. Additionally, we provide numerical calculations of a parametric study on the influence of the detection geometry on the angular distribution of the emitted γ-rays. Finally, we benchmark our simulation by comparing the simulation-estimated asymmetry ratios with those measured experimentally. The present simulation can be employed as a kernel of an implementation that simulates the nuclear resonance fluorescence process.

Virgibacillus salarius BM02 was identified as a highly exopolysaccharide (EPS) producing bacterium. The EPS production
and its physico-chemical properties (intrinsic viscosity and total sugars/protein (TS/P) ratio) were optimized
using Box-Behnken experimental design. Maximum EPS production of 5.87 g L
−1
with TS/P ratio of 12.56
and intrinsic viscosity of 0.13 dL g
−1
was obtained at optimal conditions of sucrose (4.0% w/v), peptone (0.75% w/
v) and incubation period of 4.69 day. The monosaccharide composition of EPS was mannose, arabinose and glucose
at a molar ratio of 1.0:0.26:0.08. The EPS showed high water solubility (38.5%), water holding capacity
(514.46%) and foaming capacity (55.55%). The EPS showed moderate antioxidant activity in vitro and good emulsion
stabilizing properties against several hydrophobic compounds. The emulsifying activity was stable at different
temperatures, pH and ionic strength. Additionally, the acid hydrolysate of the EPS was evaluated as a carbon
source for the mixotrophic cultivation of industrially important Spirulina platensis. It induced an enhancement of
not only biomass production of S. platensis, but also cellular contents (pigments, proteins and lipids) leading to
higher nutritional value.