Published Resarch

Abstract

The optical properties of 1 μm polystyrene in the wavelength range of 500–750nm were estimated by using a white light spectrophotometric transmittance spectroscopy and a single integrating sphere system. To retrieve the optical characteristics, two analytical methods, namely, diffusion approximation and Kubelka–Munk were used, and then their results were compared with Mie theory calculations.*ecorrespondence of the Kubelka–Munk scattering coefficient with Mie was obvious, and relative errors varied between 6.73% and 2.66% whereas errors varied between 6.87% and 3.62% for diffusion theory. Both analytical methods demonstrated the absorption property of polystyrene over the abovementioned wavelength range. Although absorption coefficient turned out to be much lower than scattering, constructing a realistic optical phantom requires taking into account absorption property of polystyrene. Complex refractive index of polystyrene based on these two methods was determined. Inverse Mie algorithm with scattering coefficient was also used to retrieve the real part of refractive index and absorption coefficient for calculating the imaginary part of refractive index. The relative errors of the real part did not exceed 2.6%, and the imaginary part was in consistence with the prior works. Finally, the presented results confirm the validity of diffusion theory with a single integrating sphere system.

Key words: Polystyrene Microsphere, Optical Properties, Kubelka–Munk equation, Diffusion Approximation, Integrating Sphere.

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https://doi.org/10.1155/2019/3406319  

Abstract

This paper aims to investigate the effect of volcanic scoria (VS) when added at micro or nano level on some concrete properties. Syria is rich in volcanic scoria with estimated reserves of nearly 1 billion tonnes. Three concrete properties, namely compressive strength, porosity and sulfate resistance, have been examined. Six percentages of micro-VS ranging from 0% to 50%, and nano-VS ranging from 0% to 5% have been used in making the investigated concretes. Test results revealed that the low early compressive strength of micro-VS-based concretes could be overcome by grinding VS to a nano size. In addition, significantly improved durability properties were obtained when VS was used either at micro or nano level. Much lower porosity and expansion values were clearly noted in the VS-based concretes. The efficiency factor (k) using the Bolomey equation and the durability indicator were evaluated to compare the behaviour of the VS-containing concrete with the reference concrete. The efficiency factor decreased with the increase of micro-VS/binder ratio and increased with the increase of nano-VS/binder. The calculated durability indicators showed that micro-VS content of 30% and nano-VS contents of 3 and 4% had approximately the highest indicator values. The replacement level of 30% at micro level and (3 & 4)% at nano level met k value of about 0.44 and 6, respectively, which would be useful for the designers of concrete mix. Based on the analyzed data, some relationships among the investigated properties were extracted. Further, scanning electron microscopy (SEM) technique and thermal gravity analysis (TGA) were employed in the current study to observe the resulting modifications in the microstructure of some VS-containing pastes. Large crystals of ettringite were observed in the pastes containing VS0 versus much smaller ones in the 3% nano-VS containing paste, after 52 weeks of exposure to 5% Na₂SO₄.

Keywords: Volcanic scoria, Nanopozzolan, Compressive strength, Concrete durability, Sulfate attack, Efficiency factor.

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https://doi.org/10.1016/j.cscm.2019.e00294

Abstract

This paper presents an application of the Cayley-Hamilton's theorem and Nakayama's lemma to study the relationship between the normal rings and valuation rings, where it is introduced some of the definitions and basic properties from commutative algebra in the first section (introduction), in the second section was presented the Cayley-Hamilton's theorem and Nakayama's lemma for finitely generated modules and a general ideal about the localization of a ring at a prime ideal. In the third section, it is proven theorem (3-5) that the localization of an unique factorization domain at an ideal generated by a prime element from this domain will be a valuation ring. In the last section it is presented in the theorem (4-1) that every valuation ring will be a normal ring and an example shows that the inverse is not true, then use the concept of the primary ideal, local ring, Cayley-Hamilton's theorem and Nakayama's lemma in theorem (4-3) to prove that every normal ring will be a valuation ring, then it is presented a result (4-4) which shows that every non-zero ideal in normal ring is written as a power ofa maximal ideal, by using the conditions in theorem (4-3).

Key words:  Normal Ring, Cayley-Hamilton's Theorem, Nakayama's Lemma, Valuation Ring.

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http://damascusuniversity.edu.sy/mag/asasy/FCKBIH/file/1%20-2018/203-222.pdf

Abstract

This study aimed to investigate the drugs misuse in community pharmacies at Damascus and the countryside area during the Syrian crisis. The cross-sectional study was conducted on 143 community pharmacists in the selected area between December 2016 and March 2017 by using a structured questionnaire. The data was collected randomly and analysed by GraphPad Prism 4.

The results indicated that drug misusers in the Countryside were higher among adolescents in comparison to Damascus. The most requested drugs were Carisoprodol and tramadol. The suspected misusers were requesting these drugs without a prescription. The drug misusers used different behavior approaches; 80.82 % of the misusers have used emotional appeal and 50.68% odd prescription. In response, pharmacists mostly denied the presence of the drugs or refused to sell them. This investigation is the first observation of prescribed drugs misuse during the Syrian crisis. This study recommends establishing an online platform between pharmacists to report such behaviors.

Key words:  Damascus, Damascus countryside, prescribed drugs misuse, Carisoprodol, Tramadol, Syrian Crisis.

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https://doi.org/10.1007/s11469-019-00180-4

Abstract

We derive an analytical formula of heat capacity based on the solutions of Ornstein–Zernike equation of Lennard-Jones potential within the Mean Spherical Approximation (MSA) assuming that the system is of low density, homogeneous, isotropic and composed of one component. We apply the derived formula to find the heat capacity at constant volume and the heat capacity at constant pressure for a number of polymers namely: Polycarbonate, Polymethylmethacrylate, Polystyrene, Polyacrylonitrile, Polyvinyl acetate, Polyvinyl propionate, Polybutylacrylate and Polyisobutylmethacrylate polymers. We also calculate the heat capacity at constant volume and the heat capacity at constant pressure for some hydrocarbons.

Key words: Heat capacity; Soft matter; Lenard-Jones potential; Ornstein-Zernike equation; Glass transition temperature.

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https://doi.org/10.1016/j.cplett.2019.136729