Effect of Flexing on the Barrier Properties of Metallized Films

One of the major concerns with respect to metallized films is the effect of flexing on their barrier properties. Films encounter a series of mechanical stress situations during manufacturing, processing, handling, and distribution. These mechanical stresses often result in flexing of the packaging film, which is more prominent with metallized films. The first part of my study evaluates the effect of real stresses of flex by using packages already manufactured and that have been through the distribution cycle. Metallized film samples from these packages were tested to see the effect of real stress on their barrier properties. The results showed an increase in the oxygen transmission rates and water vapor transmission rates of the flexed samples indicating that flexing decreases the barrier properties of metallized films. Flexing leads to the initiation of pinholes that subsequently lead to a loss in barrier properties. The second part of my study evaluates whether the Gelbo flex tester simulates the actual distribution environment encountered by flexible packages. The metallized films were submitted to 10, 50 and 100 full flex cycles on a Gelbo flex tester and their permeation rates were evaluated comparatively. The results showed that for different films, different numbers of flex cycles are required to simulate mechanical stress during processing and distribution

Design of unique composites based on aromatic thermosetting copolyesters

Aromatic thermosetting copolyester (ATSP) has promise in high-temperature applications. It can be employed as a bulk polymer, as a coating and as a matrix for carbon fiber composites (ATSP/C composites). This work focuses on the applications of high performance ATSP/C composites. The morphology of the ATSP matrix in the presence of carbon fiber was studied. The effect of liquid crystalline character of starting oligomers used to prepare ATSP on the final crystal structure of the ATSP/C composite was evaluated. Matrices obtained by crosslinking of both liquid crystalline oligomers (ATSP2) and non-liquid crystalline oligomers (ATSP1) tend to crystallize in presence of carbon fibers. The crystallite size of ATSP2 is 4 times that of ATSP1. Composites made from ATSP2 yield tougher matrices compared to those made from ATSP1. Thus toughened matrices could be achieved without incorporating any additives by just changing the morphology of the final polymer. The flammability characteristics of ATSP were also studied. The limiting oxygen index (LOI) of bulk ATSP was found to be 40% whereas that of ATSP/C composites is estimated to be 85%. Thus, ATSP shows potential to be used as a flame resistant material, and also as an aerospace reentry shield. Mechanical properties of the ATSP/C composite were characterized. ATSP was observed to bond strongly with reinforcing carbon fibers. The tensile strength, modulus and shear modulus were comparable to those of conventionally used high temperature epoxy resins. ATSP shows a unique capability for healing of interlaminar cracks on application of heat and pressure, via the Interchain Transesterification Reaction (ITR). ITR can also be used for reduction in void volume and healing of microcracks. Thus, ATSP resin systems provide a unique intrinsic repair mechanism compared to any other thermosetting systems in use today. Preliminary studies on measurement of residual stresses for ATSP/C composites indicate that the stresses induced are much lower than that in epoxy/C composites. Thermal fatigue testing suggests that ATSP shows better resistance to microcracking compared to epoxy resins

Development of a Virtual Laparoscopic Trainer using Accelerometer Augmented Tools to Assess Performance in Surgical training

Previous research suggests that virtual reality (VR) may supplement conventional training in laparoscopy. It may prove useful in the selection of surgical trainees in terms of their dexterity and spatial awareness skills in the near future. Current VR training solutions provide levels of realism and in some instances, haptic feedback, but they are cumbersome by being tethered and not ergonomically close to the actual surgical instruments for weight and freedom of use factors. In addition, they are expensive hence making them less accessible to departments than conventional box trainers. The box trainers in comparison, although more economical, lack tangible feedback and realism for handling delicate tissue structures. We have previously reported on the development of a modified digitally enhanced surgical instrument for laparoscopic training, named the Parkar Tool. This tool contains wireless accelerometer and gyroscopic sensors integrated into actual laparoscopic instruments. By design, it alleviates the need for both tethered and physically different shaped tools thereby enhancing the realism when performing surgical procedures. Additionally the software (Valhalla) has the ability to digitally record surgical motions, thereby enabling it to remotely capture surgical training data to analyse and objectively evaluate performance. We have adapted and further developed our initial single training tool method as used with a laparoscopic pyloromyotomy scenario, to an enhanced method using multiple Parkar wireless tools simultaneously, for use in several different case scenarios. This allows the use and measurement of right and left handed dexterity with the benefit of using several tasks of differing complexity. The development of a 3D tissue-surface deformations solution written in OpenGL gives us several different virtual surgical training scenario approximations to use with the instruments. The trainee can start with learning simple tasks e.g. incising tissue, grasping, squeezing and stretching tissue, to more complex procedures such as suturing, herniotomies, bowel anastomoses, as well as the original pyloromyotomy as used in the first model

Drug delivery systems to include liposomes and microparticles in order to aid treatment of glioma.

Targeted drug delivery is achieved by enhancing drug availability at the response site while minimising its availability at other sites, especially those that manifest toxicity. The effects of liposomes and polymeric nanoparticles in cancer chemotherapy have been investigated in recent years and there have been some interesting outcomes resulting in improved survival rates of the patients. Thus, the present study was carried out to investigate the effect of encapsulating TMZ and Patrin-2 into liposomes and microparticles separately in order to enhance the delivery. A validated HPLC system was used for the analysis of both TMZ and Patrin-2. First phase of our study involved the preparation of a delivery system of TMZ and Patrin-2 through liposomes in order to enhance the treatment of glioma. It involved the application of freeze-thaw and dehydration-rehydration methods to encapsulate the TMZ into liposomes. However, the desired encapsulation efficiency (EE %) of TMZ was not achieved using these methods, the maximum entrapment achieved with freeze-thaw method was 11.54 ± 0.70 % while for dehydration-rehydration method was 26.69 ± 0.34 %. Therefore the second phase focussed on preparing polymeric microparticles for continuous delivery of intact TMZ and Patrin-2 using the spray dry method. The maximum entrapment achieved using this method for TMZ was 64.32 ± 2.58 % while the maximum entrapment achieved for Patrin-2 was 68.47 ± 1.47 %, thus, this technique was found to be successful for the preparation of both TMZ and Patrin-2 loaded PLGA microparticles. Furthermore the release study of both TMZ and Patrin-2 was investigated using dispersion and dialysis methods. TMZ and Patrin-2 showed an initial burst release, however TMZ later showed decrease in concentration over the period of time while Patrin-2 showed a slow release with an increase in concentration. This novel study aids in comparing various methods used for investigating the preparation of TMZ loaded liposomes, and TMZ and Patrin-2 loaded microparticles. In preparation of liposomes based on this research dehydration-rehydration was found to be a more efficient method than the freeze-thaw method for encapsulating TMZ, while the spray dry method was found to be more effective than the emulsifying solvent evaporation method in obtaining the maximum EE % for TMZ and Patrin-2 for preparation of microparticles. The release profiles of TMZ and Patrin-2 from the microparticles was studied using the dispersion method and the dialysis bag diffusion technique however due to tome being the limited factor the technique could not be explored completely

Sjögren Syndrome Complicated by Mucosa-Associated Lymphoid Tissue Lymphoma and Lymphocytic Interstitial Pneumonia.

Sjögren syndrome (SS) is an autoimmune disease with exocrine glands dysfunction and multiorgan involvement. It is associated with increased risk of lymphoproliferative disorders, especially B-cell marginal zone lymphoma. While the role of F-18 Fluorodeoxyglucose position emission tomography/computed tomography (F-18 FDG PET/CT) for evaluation of lymphoma has been established, its use in patients with a chronic history of SS to evaluate for possible lymphoproliferative disorders or multiorgan involvement is limited. We present a case of chronic SS in which F-18 FDG PET/CT demonstrated FDG avid intraparotid and cervical lymph nodes pathologically proven to be mucosa-associated lymphoid tissue lymphoma. In addition, the patient had bibasilar cystic changes consistent with lymphocytic interstitial pneumonia

On modeling and experimental validation of extrusion process of lightweight alloys

Laboratory-scale extrusion facilitated a parametric study of the metal extrusion process under controlled conditions. Hot extrusion experiments were performed on billets of both aluminum Al1100 as well as, magnesium alloys AZ61 and AM30. Tests were designed and executed with the purpose of recording load and temperature data to validate full-scale thermo-mechanical simulations performed with the commercial code HyperXtrude. Various aspects of flat die and conical die extrusion were observed, studied and modeled with the code. Conventional sine hyperbolic inverse material model was used in the simulations due to present limitations of HyperXtrude. Although this model showed a perfect viscoplastic response at constant temperature and strain rate, by proper changes in the material parameters the model captured the stress softening response characteristic of dynamic recrystallization in magnesium alloys, as shown for the case of AZ61. A framework is also presented for designing and understanding hot extrusion experiments and simulation boundary conditions