Design and development of a microanastomosis device

Master'sMASTER OF ENGINEERIN

A new lattice fluid equation of state for associated CO₂ + polymer and CO₂ + ionic liquid systems

The phase behavior of CO2 + polymer systems is of interest in polymer synthesis, flue and natural gas processing, polymer foam and nanoparticle processing, and drug delivery. Theoretical and experimental evidence suggests that CO2 is able to interact with electron donating functional groups in polymers to form weak Lewis acid – base or EDA (Electron Donor Acceptor) complexes. These complexes can have a significant effect on the phase behavior of associated CO2 + polymer systems. In spite of this, however, the phase equilibria of only a few associated CO2 + polymer systems have been measured. Some success in modeling the phase behavior of polymer solutions has been achieved by various versions of the Statistical Association Fluid Theory (SAFT), as well as by several Lattice Models. However, many of these models incorporate two to four adjustable parameters that often depend on temperature (T), pressure (P), and/or molecular weight (MW). As a result, a large amount of experimental data is required to apply these models. The goal of the present work was therefore to develop a new thermodynamic model for associating systems that would include no more than two temperature-independent adjustable parameters. The new model presented in this work is based on the Guggenheim-Huggins-Miller lattice and includes complex formation in the development of the partition function. The EOS obtained from the resulting partition function includes two mixture parameters – the enthalpy of association or complex formation and a reference value of the equilibrium constant for complex formation . Most importantly, can be obtained from in situ Attenuated Total Reflection Fourier Transform Infrared (ATR – FTIR) measurements. This work therefore demonstrates the use of ATR – FTIR spectra to obtain molecular level information regarding the interaction of CO2 and electron donating functional groups in polymers. Unlike other studies, this work uses the bending vibration of CO2 to estimate the enthalpies of association ( ) of CO2 + polymer systems. Values of were directly incorporated in the new model and were found to lie between -7 and -12 kJ/mol for the systems investigated in this work. They increased (i.e. became more negative) in the order: CO2 + PS-co-PMMA < CO2 + PMMA <CO2 + PBMA < CO2 + PSF < CO2 + PVAc < CO2 + EVA40 < CO2 + PEG. Values of the second parameter in the new EOS ( ) were obtained by fitting solubility data at one temperature. Both and were found to be temperature independent. The application of the new EOS was demonstrated by calculating the solubility (sorption) of CO2 in polymers, the extent of swelling of polymers due to CO2, and the solubility of polymers in CO2 (cloud points). Both sorption and cloud point behavior in CO2 + polymer systems could be calculated using a single value of for each binary system. Ionic Liquids (ILs) can also incorporate electron donating functional groups in their structure. Evidence for the interaction of such ILs with CO2 can be found in the large values of the enthalpies of absorption of CO2 in these ILs. The ALF EOS was therefore extended to CO2 + IL systems using the enthalpy of absorption as a measure of association ( ) in these systems. was again treated as an adjustable parameter in the calculation of the CO2 solubility in ILs. A single value of was sufficient to predict swelling in these systems within experimental error.Ph.D

Feasibility Assessment of Warm Mix Asphalt in Arkansas

The future of Warm Mix Asphalt (WMA) technologies is promising in the U.S. However, the Arkansas Department of Transportation (ARDOT) does not have any specific guidelines to implement them in the field. This research aims to provide necessary baseline data for WMA as a proof of concept. In this study, three ARDOT approved Performance Grade (PG) binders namely PG 64-22, PG 70-22, and PG 76-22 were investigated. Each of these binders was obtained from two different sources. They were modified by varying doses of four selected additives: Sasobit®, Advera®, Evotherm®, and Rediset®. Additionally, four different types of aggregates (sandstone, limestone, gravel, and dolomite) from different quarries in Arkansas were evaluated for their compatibility with modified binders. Empirical test (Penetration test), Superpave Performance tests such as Rotational Viscometer, Rolling Thin-Film Oven (RTFO), Pressure-Aging Vessel (PAV), Dynamic Shear Rheometer (DSR), and Bending Beam Rheometer), PG Plus tests such as Multiple Stress Creep Recovery and Frequency Sweep, chemical analyses (SARA analysis, FTIR, pH), science-based test (Surface Free Energy), and Texas Boiling Test on loose mixture samples were conducted at different aging conditions. Based on the RV test results, reduced mixing and compaction temperatures have been observed for Sasobit®, Evotherm®, and Rediset® modified samples. The DSR test results suggest that both Sasobit® and Advera® can reduce rut potential. On the other hand, BBR test results indicate that both Evotherm® and Rediset® have the capabilities of improved resistances against fatigue and low-temperature thermal cracking. Binder samples modified by these have also demonstrated minimal stripping in SFE and Texas Boiling Test. Advera® has modified the chemical compositions of the neat binders, which was also observed in the SARA analysis. The findings of this study will help the agency to select the most appropriate WMA additive along with its application rate

Professional Ethics Under Islamic Perspective: A Study on Islamic Banks Operating in Bangladesh

The present study is about practice of professional ethics under Islamic perspective in Islamic Banks operating in Bangladesh. It is the outcome of primary data mainly. The requisite primary data were collected from a total number of 77 respondents on the basis of a structured questionnaire by direct interview methods from 7 Islamic banks operating in Bangladesh. The respondents were selected purposively for the easy and smooth collection of data. The main theme of the study is the practices of Islamic as well as professional ethics in the selected seven Islamic banks. The study depicts that awareness and attitudes towards the principles and practices of Islamic professional ethics have been higher is case of top level management of the banks. On the other hand, in case of the branch level management, those have been either medium or low. In order to improve the existing practice, the problems as mentioned in the study must be removed by adopting the suggestions opined by the respondents. Key words: Islamic professional ethics, Islamic management, Shariah compliance, Ethical behavior, Corporate social responsibility and Leadership

Correction to: Impact of Continuous Professional Education on Leadership for Rehabilitation Professionals in Bangladesh: A Pilot Study

In the publication of this article, the abstract, full-text of the article and the author's affiliations had some mistakes with regards to the writing/language. The abstract, full-text and the affiliations of the authors has now been updated in the original article. The authors declare that the correction does not change the results or conclusion of this paper

Impact of Continuous Professional Education on Leadership for Rehabilitation Professionals in Bangladesh: A Pilot Study

Background: In healthcare and rehabilitation profession, continuous professional education (CPE) is deemed as an essential tool by institutions, regulatory bodies and organizations. It is considered to be a safeguard to professional practice to ensure patient safety and efficient service delivery. Leadership program is an emerging subject that integrates technical, management and leadership skill that found indispensable to enhance ultimate professional development. Objective: The purpose of this article is to explore the potential impact of CPE on leadership training for rehabilitation professionals in Bangladesh. Methodology: This pilot study was a mixed methods study. 20 rehabilitation professionals participated in the study. Quantitative data were collected by structured questionnaire and qualitative data were obtained by face to face video recording interviews. Quantitative data were analyzed by Statistical Package for the Social Sciences (SPSS) &nbsp;&nbsp;and thematic analysis was considered for qualitative data. Result: Study findings showed that 95% of the participants (n=19) were in their 2nd to 3rd decade of life, there mean age were 26 and male participation (n=12) were higher than female (n=8). Highest academic qualification was master’s degree and none of the participants attended leadership training before. Overall objective, planning and atmosphere of the training course, quality of trainers and time management seemed effective and satisfactory to the participants they agreed with. Leadership qualities and elements have profound impacts on knowledge and attitude towards positivity in performing professional duties and Responsibilities. The training also enhances motivation to be a skilled professional in clinical practice, also encourages serving with outmost excellence towards patients or clients. Conclusion: The study demonstrates that education on leadership to professionals have an impact on motivation and positivity towards developing technical, management and professional skills. The study may have impact on developing diverse qualities of a professional in personal and organizational perspective; this can be explored by continuing education on leadership and evaluation of the behavioral changes, professional and management skills in rehabilitation professionals’ serving in an organization in longer run

What are the Alternatives of PG Plus Tests for Modified Asphalt Binders?

For characterizing the polymer modified binders, different state Departments of Transportation (DOTs) use different time consuming and empirical Performance Grade (PG) Plus test methods. Furthermore, the PG Plus tests are silent when asphalt binders are modified with chemicals such as polyphosphoric acid (PPA). But, the effects of the polymer are not accurately identified through these conventional tests such as Elastic Recovery (ER) and tenacity. The main goal of this study is to recommend alternative test method(s), which can possibly be pursued by using, a Dynamic Shear Rheometer (DSR). Thus, Multiple Stress Creep and Recovery (MSCR), ER-DSR, Frequency Sweep, and Binder Yield Energy Test (BYET) are being explored to find their effectiveness. Three PG binders (PG 64-22, PG 70-22 and PG 76-22) have been selected for this investigation. These binders have been prepared with styrene-butadiene-styrene (SBS) polymer, PPA, or a combination of both. Further, chemical tests such as SARA (Saturate, Aromatic, Resin, and Asphaltene) analysis and FTIR (Fourier-transform Infrared spectroscopy) are also being explored to fulfill the objectives. Preliminary findings suggest that the PG Plus tests deem to be obsolete. Also, a single test procedure is not sufficient to identify the presence and effectiveness of modifiers in the PG binders

Evaluation of Selected Performance Properties of Nanoclay-Modified Asphalt Binders

Asphalt binders are often modified with additives such as acid, polymer, or a combination of multiple additives to achieve improved performance to sustain heavy loads and adverse weather conditions. According to some previous researches, nanoclay can be a good alternative of currently practiced Styrene-Butadiene-Styrene (SBS) modification, and the former is expected to reduce the overall cost of the asphalt binder. Three types of nanoclay (Cloisite 10A, 11B, and 15A) were blended with asphalt binders prepared from two different sources (Arabian Crude and Canadian Crude). A blending protocol has been developed to blend nanoclay with the base binders. Mechanical properties including viscosity, rutting parameter have undergone significant changes after the nanoclay modification. It was also observed that nanoclay modified binders offer different moisture susceptibility while bonding with different aggregates; the nanoclay modified asphalt binder exhibits better bonding with gravel than sandstone. Mechanistic properties such as viscosity and rutting parameter are found to be highly correlated with the chemical compositions. Binders from the Canadian crude showed more colloidal stability than binders from the Arabian crude after nanoclay modification