Preparation of biodegradable polymer nanoparticles stabilized with the poly (vinyl alcohol)-sodium dodecyl sulfate mixture: Effect of the lactide/glycolide molar ratio

Abstract: This study examines the effects of the lactide/glycolide molar ratio on the synthesis of polymeric nanoparticles using a PVA-SDS stabiliser solution. PLA was obtained with a ratio of 100/0, while PLGA was synthesized at ratios of 88/12 and 64/36. Polymerizations employed ROP at 130°C with stannous octanoate and 1-dodecanol as catalysts. Polymerizations were conducted through ring opening at 130°C with stannous octanoate and 1-dodecanol as catalyst and co-catalyst. Characterized polymers were used to prepare emulsions stabilized with polyvinyl alcohol (15 g/L) alone or mixed with sodium dodecyl sulfate of various molecular weights (MW=13-23, 31-50 and 85-124 KDa). These emulsions were stored in phosphate-buffered saline for 28 days at 37.4°C. Colloidally stable emulsions were achieved using different poly (vinyl alcohol) concentrations, with the lactide/glycolide molar ratio influencing particle diameter. The electrostatic stabilizer formed by the poly (vinyl alcohol)-sodium dodecyl sulfate mixture demonstrated .Superior stabilization compared to poly (vinyl alcohol) alone, representing a novel finding. Moreover, the poly (vinyl alcohol-sodium dodecyl sulfate) mixture showed reduced water diffusion into the nanoparticles compared to poly (vinyl alcohol) alone, as evidenced by molecular weight and pH measurements. Additionally, the degradation of poly (lactic acid) and poly (lactic-co-glycolic acid) films was investigated; pH measurements in the immersed solutions showed that the degradation was increased with higher glycolide content

Improving ELT teacher training practices through planning, design and implementation of an ICT-supported INSET programme : An action research study in Qatar

This study investigates in-service teacher education and training (INSET) practices in Qatar, and employs action research (AR) as an investigative methodology. It is an attempt to improve the researcher’s practice as a teacher trainer by exploring the local INSET setting and investigating an interventionist training programme. It had its origins in personal observation that local INSET is struggling to provide effective learning opportunities to teachers who generally engage in the minimal required INSET. This study was conducted over a five-year period in three stages, with three different cohorts of in-service teachers of English language teaching (ELT). The three stages were needs analysis, implementation and reflection. The needs analysis stage aimed at gathering context information to inform the INSET design and delivery in the succeeding stages. The implementation stage consisted of three AR cycles. In the first cycle, the three-month INSET delivery involved 12 sessions, comprising 48 hours of face-to-face training. The second cycle involved around 25 INSET events for over one and a half months. In the third cycle, each of the three sessions and a demo lesson was delivered every other two weeks to allow for training input implementation and online collective discussion by trainees. The quantitative and qualitative data were collected by means of multiple methods. Quantitative data were statistically analysed while qualitative data were thematically analysed. The findings of the study provided insights on the teachers’ attitudes towards INSET, main challenges, perceived success factors, preferred training themes, engagement, and trainer role. This study contributes to understandings of INSET in the Qatari context. It was conducted at a time of major reforms where INSET is seen as one of the main tools to address policy makers’ concerns about the educational system. Albeit, minimal academic research has been conducted on the effectiveness of the teacher training programmes offered to TESOL practitioners in Qatar. The findings provide ways to improve INSET, shed light on how the role of a trainer can contribute to its success, explain why teachers in Qatar may not be motivated to take part in INSET, and propose a framework for INSET design and delivery in the Qatari and other ELT contexts

Closed form solution for a double quantum well using Gr\"obner basis

Analytical expressions for spectrum, eigenfunctions and dipole matrix elements of a square double quantum well (DQW) are presented for a general case when the potential in different regions of the DQW has different heights and effective masses are different. This was achieved by Gr\"obner basis algorithm which allows to disentangle the resulting coupled polynomials without explicitly solving the transcendental eigenvalue equation.Comment: 4 figures, Mathematica full calculation noteboo

Ensuring telecommunication network security through cryptology: a case of 4G and 5G LTE cellular network providers

This paper aims to present the details regarding telecommunication network security through cryptology protocols. The data was based on scientific data collection and the quantitative method was adopted. The questionnaire was developed and the primary respondents were approached who were working in 4 telecommunication networking companies namely Huawei, Ericsson, SK Telecom and Telefonica. The sample size of the research was 60 participants and the statistical analysis was used to analyze research. The finding shows that cryptology protocol such as SSH, SSL, Kerberos PGP and SET are implemented within the companies in order to secure network

Analysis of Treated Wastewater Produced from Al-Lajoun Wastewater Treatment Plant, Jordan

Abstract: Assessment of treated wastewater produced from Al-Lajoun collection tanks of the wastewater treatment plant in Karak province was carried out in term of physical properties, its major ionic composition, heavy metals and general organic content, for both wastewater influent and effluent. Sampling was done in two periods during (2005)(2006) summer season and during winter season to detect the impact of climate on treated wastewater quality. Soil samples were collected from Al-Lajoun valley where the treated wastewater drained, to determine the heavy metal and total organic carbon concentrations at same time. The study showed that the treated wastewater was low in its heavy metals contents during both winter and summer seasons, which was attributed to high pH value enhancing their precipitations. Some of the major ions such as Cl -, Na + , HCO 3 -, Mg 2+ in addition to biological oxygen demand and chemical oxygen demand were higher than the recommended Jordanian guidelines for drained water in valleys. The treated wastewater contained some organic compounds of toxic type such as polycyclic aromatic hydrocarbons. Results showed that the soil was low in its heavy metal contents and total organic carbon with distance from the discharging pond, which attributed to the adsorption of heavy metals, total organic carbon and sedimentation of suspended particulates. From this study it was concluded that the treated wastewater must be used in situ for production of animal fodder and prohibit its contact with the surface and groundwater resources of the area specially Al-Mujeb dam where it is collected

Determination of the carrier concentration in InGaAsN∕GaAs single quantum wells using Raman scattering

Raman scattering from longitudinal optical phonon-plasmon coupled mode was observed in a series of InGaAsN∕GaAs single quantum well samples grown by metalorganic vapor phase epitaxy. The phonon-plasmon mode spectra were fitted with the dielectric constant function based on Drude model that contains contributions from both lattice vibrations and conduction electrons. The carrier concentration is calculated directly from the plasmon frequency, which is obtained from the fitting procedure. An empirical expression for the electron concentration, [n], in InGaAsN∕GaAs samples is determined as [n]≈{2.35×1016(ωm−502)}cm−3, where ωm is the peak of the upper frequency branch, L+, of the phonon-plasmon mode measured in unit of cm−1. The phonon-plasmon coupled mode was also investigated in rapid thermally annealed samples

Electron-Paramagnetic-Resonance Study of GaAs Grown by Low-Temperature Molecular-Beam Epitaxy

Electron-paramagnetic-resonance results demonstrate an arsenic-antisite related deep donor defect to be the dominant native defect in GaAs layers grown by low-temperature molecular-beam epitaxy (LTMBE). This defect is different from the EL2-related native arsenic-antisite defect. The thermal-equilibrium concentration of 3×1018 cm−3 ionized AsGa defects directly shows the additional presence of unidentified acceptor defects in the same concentration range. The defect distribution in GaAs grown by LTMBE is unstable under thermal annealing at T≳500 °C

Infrared optical absorbance of intersubband transitions in GaN/AlGaN multiple quantum well structures

Intersubband transitions in Si-doped molecular beam epitaxygrown GaN/AlGaN multiple quantum wells on c-plane sapphire were investigated using the Fourier-transform infrared optical absorption technique. Several GaN quantum well samples were grown with either AlGaN bulk or GaN/AlGaN short period superlattice barriers. The measurements were made in a waveguide configuration utilizing a facet polished at 45° to the c plane. The integrated area of the intersubband transitions in several waveguides cut from different location of the wafer was measured, from which we estimated the two-dimensional electron gas density (σ). The measured values of σ are about two orders of magnitude larger than the Si doping level of ∼8×1017 cm−3, which is consistent with the polarization effects, particularly considering the large number of GaN/AlGaN interfaces. The internal quantum efficiency of the intersubband transitions was estimated to be on the order of 40% for samples with superlattice barriers

Radiation-resistant ultraviolet curable polyurethane films with CdSe-ZnS сore-shell nanocrystals

The effect of proton fluence of different doses (up to 9×10¹⁵ protons/cm² ) on the absorption spectra of UV-cured polyurethane films doped by CdSe/ZnS nanocrystals has been investigated. We found that the degradation of this type of protective coating is related to the degradation of polyurethane film itself, but not the CdSe/ZnS nanoparticles