Liposome: classification,preparation, and applications

Liposomes, sphere-shaped vesicles consisting of one or more phospholipid bilayers, were first described in the mid-60s. Today, they are a very useful reproduction, reagent, and tool in various scientific disciplines, including mathematics and theoretical physics, biophysics, chemistry, colloid science, biochemistry, and biology. Since then, liposomes have made their way to the market. Among several talented new drug delivery systems, liposomes characterize an advanced technology to deliver active molecules to the site of action, and at present, several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles to ‘second-generation liposomes’, in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. This paper summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations in respect to industrial applicability and regulatory requirements concerning liposomal drug formulations based on FDA and EMEA documents.     

Attitudes of Kuwaiti parents toward physical punishment of children

OBJECTIVE: The major aim was to describe parental attitudes to physical punishments and examine their sociodemographic correlates. A related aim was to assess the association of parents' own experience of physical punishment with attitudes to punishment of children. METHOD: A cross-sectional survey was conducted during the second week of December, 1996 in five general clinics covering the major administrative areas of Kuwait: 337 Kuwaiti mothers and fathers with at least one living child were contacted; 95% were successfully interviewed using a structured questionnaire. RESULTS: Eighty-six percent of parents agreed with physical punishment as a means of child disciplining. Agreement with punishment was higher in case of serious misbehaviors such as stealing (63%), sniffing glue and using drugs (77%). Multiple regression results showed that parent's lower level of education and Bedouin ethnicity were positively associated with agreement on physical punishment. Larger percentages of parents who had experienced physical punishments themselves agreed with such punishment to discipline their children, but this was not statistically significant. CONCLUSIONS: In recent years education has become widespread for both sexes. An inverse association between educational level and agreement on physical beating suggest that attitudes to this form of child disciplining are changing. Those with a Bedouin ethnic background still adhere more strictly to the traditional forms of child disciplining including physical beating. There is a need for conducting research on the possible negative psychosocial impacts of physical punishment in view of findings from other countries.     

Integral boundary layer heat transfer modeling for Tehran Research Reactor

In the present work the validity of applying the Boussinesq approximation in the analysis of natural convection heat transfer along nuclear fuel plates with large coolant channel aspect ratios is evaluated. The Boussinesq approximation is introduced into the integral boundary layer equations governing the system to describe the velocity and temperature distributions of the coolant in the cooling channels. The fuel plate temperature is related to the adjacent coolant fluid temperature by a fundamental law in conduction heat transfer. Air and water are considered as fluids. The coolant flow is assumed to be fully developed which is a convenient assumption for coolant channels having large aspect ratios. Obtained results indicate that the Boussinesq approximation is merely applicable over a limited range of coolant channel outlet fluid temperatures. The use of this approximation produces conservative estimation of the critical plate power for air flow and non-conservative estimation of the critical plate power for water flow.     

Synthesis of 2-imino-1,3-dithiolanes containing trimethylsilylethynylthiolato groups

An efficient, eco-friendly, and simple one-pot approach for the synthesis of 2-imino-1,3-dithiolanes via reaction of allyl chloride, primary amines, carbon disulfide, and I₂ under solvent-free conditions is presented. The obtained 5-iodomethyl-2-imino-1,3-dithiolanes were converted into silyl-protected terminal alkynyl sulfides substituted 2-imino-1,3-dithiolanes by treatment with lithium 2,2,2-tris(trimethylsilyl)ethanedithioate, produced by the reaction of tris(trimethylsilyl)methyllithium (TsiLi) with CS₂.     

Multiresponse optimization with consideration of probabilistic covariates

In many complex experiments, nuisance factor may have large effects that must be accounted for. Covariates are one of the most important kinds of nuisance factors that can be measured but cannot be controlled within the experimental runs. In this paper a novel approach is proposed, based on goal programming, to find the best combination of factors so as to optimize multiresponse‐multicovariate surfaces with consideration of location and dispersion effects. Furthermore, it is supposed that several covariates considered in the experiment have probability distributions of known form. One objective is to find the most probable values of each covariate. For this purpose, a multiobjective mathematical optimization model is proposed and its efficacy is demonstrated by two numerical examples. Copyright © 2010 John Wiley & Sons, Ltd.     

Solid phase extraction of ultra traces mercury (II) using octadecyl silica membrane disks modified by 1,3-bis(2-ethoxyphenyl)triazene (EPT) ligand and determination by cold vapor atomic absorption spectrometry

A facile and highly efficient method was developed for the preconcentration of the ultra trace amounts of mercury (II) ions. Octadecyl silica membrane disk was modified by the recently synthesized triazene ligand, 1,3-bis(2-ethoxyphenyl)triazene (EPT), and cold vapor atomic absorption spectrometry was used to determine the resultant preconcentrated Hg(II) ions. Solution studies with EPT and a series of metal ions were done in advance, and the results showed a strong affinity of EPT to the mercury ions. To perform solid phase extraction, various parameters such as pH of the sample, flow rates and the amount of the ligand were optimized. A linear calibration curve was obtained in the range of 0.02-1.90 μg L⁻¹ with r² = 0.9990 (n = 8), and the limit of detection (LOD) based on three times the standard deviation of the blank was 10.6 ng L⁻¹. The relative standard deviation (RSD) for the determination of 0.1 μg L⁻¹ Hg(II) found to be 2.9% while a RSD value of 1.1% was obtained for the determination of 1.0 μg L⁻¹ Hg(II) (n = 8). The preconcentration and improvement factors were 380 and 74, respectively. The newly developed method was successfully applied to the determination of mercury ions in real water samples.     

Feasibility study for Tehran Research Reactor power upgrading

The present work is concerned with a power upgrading study of Tehran Research Reactor (TRR). The upgrading study is aimed at investigating the possibility of raising power of the TRR from the current level of 5 MW_th to a higher level without violating the original thermal-hydraulic safety criteria. The existing core, comprising 22 standard fuel elements and five control fuel elements, is used for the analyses. Different reactor thermal powers (5–11 MW) and different core coolant flow rates (500–921 m³/h) are considered. It is shown that, for the present core, this goal could be achieved safely by gradually opening the butterfly control valve until the desired coolant flow rate is reached. The TRR power could be upgraded up to around 7.5 MW_th with the total power peaking factor maintained at less than or equal to 3.0.     

Simulation modelling and analysis of scheduling in robotic flexible assembly cells using Taguchi method

Due to increasing competition in the developing global economy, today’s companies are facing greater challenges than ever to employ flexible manufacturing systems (FMS) capable of dealing with unexpected events and meeting customers’ requirements. One such system is robotic flexible assembly cells (RFACs). There has been relatively little work on the scheduling of RFACs, even though overall scheduling problems of FMS have attracted significant attention. This paper presents Taguchi optimisation method in conjunction with simulation modelling in a new application for dynamic scheduling problems in RFACs, in order to minimise total tardiness and number of tardy jobs (N_T). This is the first study to address these particular problems. In this study, Taguchi method has been used to reduce the minimum number of experiments required for scheduling RFACs. These experiments are based on an L9 orthogonal array with each trial implemented under different levels of scheduling factors. Four factors are considered simultaneously: sequencing rule, dispatching rule, cell utilisation and due date tightness. The experimental results are analysed using an analysis of mean to find the best combination of scheduling factors and an analysis of variance to determine the most significant factors that influence the system’s performance. The resulting analysis shows that this proposed methodology enhances the system’s scheduling policy.