Micellization Behavior of Ionic Surfactants in Presence of Butanol Isomers in Non-aqueous Solutions

Electrical conductivity and surface tension measurements of various surfactants, such as sodium caprylate, sodium laurate, sodium palmitate and sodium stearate micellar solution,  containing  1-butanol  (1-BuOH),  2-butanol  (2-BuOH)  and tertiary butanol (t-BuOH) in n,n-dimethyl acetamide have been determined at various temperatures. Both methods show that micelles are formed in n,n-dimethyl acetamide  (DMA) solution in the presence of butanol isomers. Critical micelle concentration (cmc) has been determined for each of the surfactants. Critical micelle concentrations have also been measured as a function of temperatures and concentration of butanol isomers added. It is suggested that the addition of alcohol leads to an increase in n,n-dimethyl acetamide penetration into the micellar interface that depends on the alkyl chain configuration for three isomeric alcohols. Thermodynamic parameters of micellization, enthalpy  (ÄH0m,  entropy  (ÄS0m),  and free energy  (ÄG0m)  were determined from the temperature  dependence of  CMC.  The solvent composition dependence of these thermodynamic parameters is determined in terms of the effect of additives on the micellization of ionic surfactants. It is observed that both ÄH0m and ÄS0m bear out not only the observed order of decrease in cmc but also account reasonably the effects produced by differences in alkyl chain configuration for these isomeric alcohols. In all cases ÄG0m < 0, and remained practically constant over the entire solvent composition range studied.  It is suggested that due to different structural consequences of intermolecular interactions,  both enthalpy and entropy must differ in a  mutually compensating manner so that G0m is not significantly affected

Thermodynamics of Dissociation and Micellization of Sodium Surfactant Solutions in Formamide

Electrical conductivity and surface tension measurement of sodium surfactants, such as sodium caprylate, sodium laurate, sodium palmitate and sodium stearate, in formamide has been determined at different temperatures. The methods show that micelles are formed in formamide solution. Critical micelle concentration (CMC) has been determined for each of the sodium surfactants. The result show that these surfactants behave as a weak electrolyte in dilute solution of formamide below the critical micellar concentration, and the conductance result can be explained on the basis of Ostwald’s formula and Debye–Huckle’s theory of weak electrolytes. The dissociation constant and thermodynamic parameters for dissociation and micellization processes of these surfactants are also evaluated. The micellization process has been found to be predominant over the dissociation process. Keywords: Critical Micelle Concentration (CMC), Micellization, Conductivity, Dissociation, Thermodynamics, Surface Tensio

Application of Neural Networks and Adaptive-Network-Based Fuzzy System in the Prediction of Optimum Bitumen Content for Asphaltic Concrete Mixtures

The objective of this study is to explore the applicability of artificial neural networks (ANNs) and Adaptive-Network-Based fuzzy System (ANFIS) for predicting the bitumen content (OBC) of asphaltic concrete mixtures based on the experimental data. Samples were collected from different regions in Makkah region in Saudi Arabia during construction and tested at laboratories of Umm Al-Qura University for bitumen content, gradation of aggregate determination. Asphaltic concrete mixtures data were used to test the performance of the ANNs and ANFIS models. Among the two ANN models (a feed-forward back propagation (BP) and a radial basis function (RBF)) employed for this investigation, the BP neural network was found to be superior to RBF network for prediction of the OBC of asphaltic concrete mixtures. For improving model prediction efficiency, optimization of network structure and spread are important for BP and RBF types of the network, respectively. A BPNN model having a structure 3-8-4-1 (three neurons in input and eight neurons in first hidden layers, four neurons in second hidden layer and one neuron in output layer) produced better prediction performance efficiencies with an accuracy of 96.37%. The BPNN (3-8-4-1) model was fairly close to the corresponding actual values of OBC with the average error of 1.1854% and 1.01% for trained and tested data respectively. The results of the testing of ANFIS were indicated almost same performance of the BPNN (3-8-4-1) model

Soliton-potential interaction in the nonlinear Klein-Gordon model

The interaction of solitons with external potentials in nonlinear Klein-Gordon field theory is investigated using an improved model. The presented model has been constructed with a better approximation for adding the potential to the Lagrangian through the metric of background space-time. The results of the model are compared with another model and the differences are discussed.Comment: 14 pages,8 figure

Pleural Fluid Analysis: Standstill or a Work in Progress?

Pleural fluid analysis yields important diagnostic information in pleural effusions in combination with clinical history, examination, and radiology. For more than 30 years, the initial and most pragmatic step in this process is to determine whether the fluid is a transudate or an exudate. Light's criteria remain the most robust in separating the transudate-exudate classification which dictates further investigations or management. Recent studies have led to the evaluation and implementation of a number of additional fluid analyses that may improve the diagnostic utility of this method. This paper discusses the current practice and future direction of pleural fluid analysis in determining the aetiology of a pleural effusion. While this has been performed for a few decades, a number of other pleural characteristics are becoming available suggesting that this diagnostic tool is indeed a work in progress

Influence of Eysenckian Personality Traits in Choice of Specialization by Young Omani Doctors.

Objectives:The role of personality in occupational specialty choices has been explored in many parts of the world. To our knowledge, there is a dearth of such studies in the Arab/Islamic population and Oman is no exception. This study aimed to explore the relationship between personality traits and specialty choice among residents of Oman Medical Specialty Board (OMSB). Methods: A cross-sectional study was carried out among Omani resident physicians working under OMSB. The Eysenck Personality Questionnaire–Revised was employed to quantify personality subtypes (e.g., psychoticism, extraversion, and neuroticism). Specialties were categorized as surgical, medical, and diagnostics as per standard of North American medical specialties. A total of 255 residents in 17 medical specialties participated in the study (m = 40.4%; f = 59.6%) of 300 eligible subjects giving a response rate of 85.0%. Results: Respondents who had chosen surgical specialties scored significantly higher on the psychoticism subscale than those who had opted for medical and diagnostic specialties. As for individual specialties, orthopedic respondents had statistically significant higher mean scores on psychoticism and neuroticism compared to radiologists and psychiatrists who scored the lowest in the two personality traits, respectively. Conclusions: This study found statistically significant associations between personality traits and choices of specialty by young Omani doctors. We recommend more detailed studies that examine further psychological and cultural variables that are likely to affect the choices of specializations by young Omani professionals in both medical and non-medical fields

Burnout Syndrome Among Primary Care Physicians in Oman

Objectives: Medical professionals are exposed to many job stressors everyday, which can lead to psychological disturbances as well as burnout syndrome. We sought to assess the level of burnout among primary care physicians (PCPs) in Oman and explore risk factors for its development. Methods: We conducted a cross-sectional, analytical study among a random cluster sample of 190 PCP working in Muscat, Oman. Indices of burnout (emotional exhaustion (EE), depersonalization (DP) and personal accomplishment (PA)) were noted using the Maslach Burnout Inventory-Human Services Survey (MBIHSS). We also used a questionnaire to obtain sociodemographic and job characteristics data. We used a binary logistic regression model and both unadjusted and adjusted odds ratios for statistical analysis. Results: The prevalence of burnout in all three dimensions was 6.3%. High levels of MBI-HSS subscales were reported on EE, DP and PA with 17.8%, 38.2%, and 21.5%, respectively. Logistic regression analysis revealed that working over 40 hours per week was the most important risk factor for burnout among PCPs. Conclusions: A total of 6.3% of PCPs working in urban areas in Oman suffered burnout. Long working hours was strongly associated with high occupational burnout. Solutions to eliminate or decrease the rate of burnout involve institutional changes, primarily respecting weekly working hours, and in more severe cases psychotherapy help is very important

Perception of Preparedness for Clinical Work Among New Residents: A Cross-sectional Study from Oman.

Objectives: To evaluate new residents’ perceptions of their own preparedness for clinical practice and examine the associated factors. Methods: This is a cross-sectional study conducted on August 20−23, 2016. New residents accepted for postgraduate training by Oman Medical Specialty Board were asked to complete the Preparation for Hospital Practice Questionnaire (PHPQ). Data was analyzed using the Statistical Package for the Social Sciences version 22. Results: A total of 160 residents were invited to participate in this study. Out of 160, 140 residents participated (87.5%), 70.7% were female and 59.3% were graduates from Sultan Qaboos University (SQU). Ninety-nine percent of the graduates were either ‘well prepared’ or ‘fairly well prepared’ for hospital practice. Male residents scored higher in the confidence scale, while residents who did a post-internship general practice placement scored higher in understanding science. Graduates from Oman Medical College felt more prepared compared to graduates from SQU. Conclusions: Most of the new residents were well prepared to clinical work. Factors such as place of undergraduate study, training, and duration of internship significantly influenced the residents’ perception of preparedness. Addressing these factors will enhance residents’ preparedness for clinical work

Prevalence and Correlates of Depressive Symptoms among Medical Students: a Crosssectional Single-centre Study

Background: Depressive symptoms are common among medical students. The aim of the present study was to determine the prevalence and risk factors of depressive symptoms among medical students in Sultan Qaboos University in Oman. Method: A cross-sectional study was conducted among a random sample selected from 1041 medical students at Sultan Qaboos University, Oman. The Patient Health Questionnaire-9 (PHQ-9) was used to screen for depressive symptoms. A logistic regression model was used to determine risk factors for depressive symptoms. Results: Of 197 medical students selected, 189 (61 men and 128 women) responded. The PHQ-9 results showed that the prevalence of depressive symptoms was 41.3%. In multivariate analysis, female students were more likely than male students to develop depression (adjusted odds ratio = 2.866, p = 0.004). Medical students with a family history of depression were more likely to develop depression than those without a family history of depression (adjusted odds ratio = 4.150, p = 0.014). Conclusion: Depressive symptoms are common among medical students in Sultan Qaboos University. Risk factors for depressive symptoms are female sex and family history of depression