The Role of Specific Interactions on the Dispersion and Properties of Carbon Nanotube-Polymer Nanocomposites

This dissertation presents work that exammes the role of specific chemical interactions in enhancing the dispersion of carbon nanotubes in a polymer matrix. Carbon nanotubes (CNT) possess unique mechanical, electrical and thermal properties hence can have a number of potential applications including high strength, light weight composites. Due to strong interaction among nanotubes, they stay as aggregates and hence their full potential for application is severely limited. Utilization of specific chemical interactions to induce/improve miscibility in polymer blends is well known. In this thesis, this approach is applied to carbon nanotubes polymer composites to enhance the dispersion of nanotubes in a copolymer of styrene and vinyl phenol with the idea that oxygenated functional groups on the nanotubes surface may potentially interact with the vinyl phenol groups on the polymer chain via hydrogen bonding. The first part of this thesis compares methods to oxidize carbon nanofibers by using various oxidizing agents, such as 6M HNO3, KMnO4, RuO4, and a mixture of concentrated H2SO4/HNO3. The efficacy of an oxidizing agent is discussed in terms of the yield of oxidized nanofibers and the amount of oxygenated functional groups generated on the nanofiber surface. Next, the dispersion of single walled carbon nanotubes (SWNT) in the matrix of a copolymer of styrene and vinyl phenol containing 0, 10, 20, 40 and 100% vinyl phenol, is examined. This study provides a method to control the dispersion of nanotubes in the polymer matrix by utilizing specific chemical interactions. The dispersion of the nanotubes was observed by optical microscopy. The dispersion of the SWNT in the polymer matrix is also quantified by optical microscopy and Raman spectroscopy. Raman spectroscopy is also used to investigate preferred interactions between the SWNTs and the copolymers via the shift in the characteristic Raman peak of the SWNTs in the composites. All composites show regions of SWNT aggregates, however the aggregate size varies with composition of the PSVPh copolymer and the amount of SWNT oxidation. Optimal dispersion of the SWNT is observed in PSVPh with 20% vinyl phenol and oxidized nanotubes, which correlates with spectroscopic evidence that indicates that this system also incorporates the most interactions between SWNT and polymer matrix. Polymer nanocomposite films containing 5 wt% single-walled carbon nanotubes (SWNT) or 5 wt% multi-walled carbon nanotubes (MWNT) with PSVPh copolymers were processed from dimethyl formamide solutions. The vinyl phenol mole ratio in the copolymers was 0, 10, 20, 30, and 40%. FTIR analysis indicates that the composites containing the copolymer with 20% vinyl phenol exhibit the maximum intermolecular interactions (hydrogen bonding) between the hydroxyl group of the vinyl phenol and the carbon nanotube functional groups. Tensile properties and electrical conductivity also are the highest in the samples containing the copolymer with 20% vinyl phenol. Thus, these results show that the optimization of the extent of intermolecular interactions between a polymer chain and a carbon nanotube results in an optimal increase in macroscopic properties. Moreover, the extent of intermolecular hydrogen bonding can be improved by optimizing the accessibility of the functional groups to participate in the non-covalent interaction. In this system, this optimization is realized by control of the amount of vinyl phenol in the copolymer, i.e., the copolymer composition. Finally, the approach of utilizing intermolecular interaction to enhance dispersion and properties was applied to composites of carbon nanofibers. Dynamic mechanical analysis (OMA) and differential scanning calorimetry (DSC) indicate that the composites prepared from oxidized nanofibers exhibit improved thermal and structural properties relative to those prepared from unoxidized nanofibers. The optimum enhancement in the mechanical and thermal properties was observed for the composite formed from oxidized nanofiber and the copolymer containing 20% vinyl phenol

One Pot Synthesis and Characterization of Mono and Di-Substituted Azo-Containing Amides

Azo-containing amides and their derivatives were synthesized by the reaction of 4-(phenyldiazenyl)aniline with different substituted benzoyl chlorides. The characterization of these synthesized compounds were based on their IR, 1H NMR spectra and elemental analysis with excellent yields

Numerical analysis of flight conditions at the Alta airport, Norway

In this paper, the results from a numerical study of the atmospheric flow characteristics at the Alta airport, Norway are presented. Experiences of the pilots operating in the region have been used to validate the findings. Further analysis has resulted in the identification of dangerous zones for aviation activities for a particular wind direction. Towards the end an effort has been made to relate the experience of the pilots with the mountain waves generated due to the presence of a small hill close to the airport

Knowledge and Awareness about Genetic Problems Associated with Consanguineous Marriages among Non-Medical Students of Islamabad

Objective: To access the level of knowledge of non-medical students about genetic problems related to consanguinity. Methodology: A descriptive study was conducted from September 2015 to June 2016 to collect information regarding acquaintance and perceptions about, consanguineous marriages among students of different colleges and universities of Federal Capital. Specially designed performa was used to collect data. The collected data was analyzed by using Statistical Package for Social Sciences (SPSS) software version 16.0. Demographic characteristics of participants were calculated as Mean±SD. Chi-square test was applied to check the level of significance among different categorical variables. Results: A total of 424 students were surveyed, out of which 155 (36.6%) were male and 269 (63.4%) were female. The mean age of the study population was 20.39 ±2.44. The data analysis showed only 9.7% of students are fully aware of the problems associated with consanguinity. Girls were found to be more aware as compared to boys (p= 0.05) and among all ethnic groups, Punjabis were found to be more aware (16.9%). In subjects with a history of parental consanguinity and consanguinity in siblings, low level of awareness (8.8% and 8.5% respectively) was found. Conclusion: Efforts should be made to increase the knowledge about consanguinity and its association with genetic diseases among non-medical students.&nbsp

Quality of Life in Patients with Stoma

Objective: To determine the quality of life of patients with stoma at tertiary care Hospital. Methodology: This prospective study has been conducted at the general surgery department, Pakistan Institute of Medical Sciences hospital Islamabad (PIMS). The study was conducted from September 2019 to February 2020. All the patients having age more than 12 years, underwent intestinal stoma formation and either gender were included for study. Patients were interviewed regarding their routine activities after stoma and the impact of it on their social life including working status, sexual activities and life satisfaction. All the information of patients including demographic data was documented via self-derived proforma. Analysis of data was done by SPSS version 20. Results: Total 46 patients were studied having a stoma and were interviewed regarding their quality of life. The patient's mean age was 44.93+6.78 years. Out of all 34.8% were working currently and rest of the patients were still on bed rest.  34.8% were satisfied with sexual life. 71.7% were depressed after stoma surgery and 52.2% were hopeful about their future. 63% were socialised with peoples as before, 58.7% replied that stoma has affected their recreational activities and 52.2% answered that they can’t travel in any way. However according to overall satisfaction, 32.6% of patients were disagreeing, 34.8% were agreeing and 30.4% were undecided. Conclusion: It was concluded that almost half of the patients were satisfied and they are performing social and daily life activities however almost half of the patients needed psychological, financial, and relative support. Key words: Stoma, Quality of lif

Perforated appendix! An experience of a Public teaching hospital

Introduction  The most common cause of non-traumatic acute abdominal pain as well as the most common acute abdominal condition presenting to Surgical Emergency is none other than Acute Appendicitis hence it becomes the most common entity undergoing surgery in Emergencies all over the world. The lifetime risk for someone to develop acute appendicitis is 8.6% and 6.7% for males and females respectively, with 90% found in children and young adults and 10% in patients over 60 years of age.1 Increasing age or in other words decreasing immunity does affect the incidence of perforated appendix as we see the  the perforation rate in acute appendicitis is approximately 20~30%  but as the age goes beyond 60 years it inclines to  32-72%.2 Delay in the diagnosis caused by indefinite  history and physical examination  tends to contribute to higher incidence of perforated appendix as reported by Siripong et al. In another study the risk factors that were found to be associated with perforated appendicitis were male sex, fever ≥ 38°C, anorexia, and duration of pain in the pre-admission period.3 In one of the the study pre-hospital delays were exceeding related to perforation as compared to in-hospital delays which was explainable because of a linear relationship present among the pathological grade  to hospital interval ratio , thus leading to increased risk of perforation.4 As far as the blood work was concerned , an increase in Total Leucocyte count with majority being polymorphonuclear leukocytes (PMN), and raised C-reactive protein (CRP) levels were found to be responsible for substantial increment in the  risk and gravity of complications in appendicitis. Presence of comorbid diseases didn't show any significant affect on perforation rate.5

Surgical Outcome of Corrosive Induced Antropyloric strictures

Introduction: Corrosive induced upper gastrointestinal tract injuries in pediatric patients, is not easy to treat. Interestingly only few reports are available in English literature highlighting the management and surgical outcome of corrosive induced antropyloric strictures. The aim of this study was to determine the presenting features, management and outcome of patients treated at our institute with corrosive induced antropyloric strictures.Methods: This retrospective descriptive study was conducted at Paediatric Surgery Department of Children Hospital & Institute of Child Health, Lahore. Medical records of patients admitted for corrosive-induced gastric out let obstruction from January 2013 to December 2018 were included. The demographic, preoperative assessment, investigations, surgical procedure and follow up details were noted in a proforma. Results were analyzed by descriptive statistics using SPSS version 20. The quantitative variables were presented as mean ± SD. Qualitative variables were presented as frequency and percentages.Results: A total of 62 patients were included in this study. The mean age at presentation was 4.9 ±3.9 years. Of these 67.7% were male and the mean weight of children at the time of surgery was 12.6 ± 5.0 kilo grams. Bathroom cleaner was ingested by 77.4%. Vomiting was seen 100% cases while abdominal pain and weight loss was seen in 38.7 %, and 80.6% respectively. We preformed Heinke-mikulicz pyloroplasty in 59(95.2%) patients, Billroth II in 1(1.6%) and gastrojejunostomy in 2(3.2) cases. Postoperatively 40 children remained well during early post- op period while leak and respiratory issue were seen in 11.9% and 13.6% patients respectively. The mean hospital stay was 27.9±11.5 days. Two patients died after surgery and the rest were discharged. Mean fallow up 15.2±70 months. Of 60 discharged children 37 (62.7%) had no issue while 4 (6.8%) had leakage from previous jejunostomy site leak other 19 patients were lost to follow up.Conclusion:We conclude that surgical treatment for Antropyloric strictures due to corrosive injuries is an acceptable option with minimal complications. However, we emphasize on the preventive measure, child-proof containers and legislations to be taken by authorities and social welfare societie