Feasibility of using 3D printed molds for thermoforming thermoplastic composites

This thesis presents a novel combined experimental and numerical mechanics approach for characterizing 3D printed thermoplastic materials by the fused deposition modeling process for thermoforming thermoplastic composites. The implications of this work are: a methodology for model-based performance evaluation of 3D printed structural parts, and an improved design of 3D printed molds for composites manufacturing, which has potential for material innovations and scaled-up applications in additive manufacturing. The thesis formulates basic criteria for selection of thermoplastic polymer used for the 3D printed mold based on forming temperatures. The thesis creates a lattice and shell finite element model of the 3D printed part to characterize its linear elastic mechanical properties and validates this model by mechanical experiments on 3D printed coupons. The thesis studies the thermomechanical and creep properties of a 3D printed polymer and implications of these behaviors on mold making. The thesis creates an idealized orthotropic solid finite element model for the lattice internal structure of 3D printed parts. The mechanical properties of this orthotropic solid are obtained from the virtual experiments carried out on the lattice and shell finite element model. This orthotropic solid finite element model is validated through mechanical experiment on 3D printed molds subjected to forming pressures. Finally, an optimization technique is outlined to create and optimal internal structure for the 3D printed polymer part

Update of a comparative analysis of cost minimization following the introduction of newly available intravenous iron therapies in hospital practice

Sunil BhandariDepartment of Renal Medicine, Hull and East Yorkshire Hospitals National Health Service Trust and Hull York Medical School, Kingston upon Hull, UKBackground: The clinical need to be able to administer high doses of intravenous iron conveniently as a rapid infusion has been addressed by the recent introduction of ferric carboxymaltose and subsequently iron isomaltoside 1000. Neither requires a test dose. The maximum dose of ferric carboxymaltose is 1000 mg. The maximum dose of iron isomaltoside 1000 is based on 20 mg/kg body weight without a specified ceiling dose, thereby increasing the scope of being able to achieve total iron repletion with a single infusion. This ability to give high doses of iron is important in the context of managing iron deficiency anemia, which is associated with a number of clinical conditions where demands for iron are high. It is also an important component of the strategy as an alternative to blood transfusion. Affordability is a key issue for health services. Recent price changes affecting iron sucrose and ferric carboxymaltose, plus modifications to the manufacturers’ prescribing information, have provoked this update.Methods: This study is a comparative analysis of the costs of acquiring and administering the newly available intravenous iron formulations against standard treatments in the hospital setting. The costs include the medication, nursing costs, equipment, and patient transportation. Three dosage levels (600 mg, 1000 mg, and 1600 mg) are considered.Results and conclusion: The traditional standard treatments, blood and iron sucrose, cost more than the alternative intravenous iron preparations across the dose spectrum and sensitivities. Low molecular weight iron dextran is the least expensive option at the 1600 mg dose level but has the caveat of a prolonged administration time and requirement for a test dose. At 600 mg and 1000 mg dose levels, both iron isomaltoside 1000 and ferric carboxymaltose are more economical than low molecular weight iron dextran. Iron isomaltoside 1000 is less expensive than ferric carboxymaltose at all dose levels. Newly available iron preparations appear to be clinically promising, cost effective, and practical alternatives to current standards of iron repletion.Keywords: iron isomaltoside 1000, ferric carboxymaltose, iron deficiency anemia, single high dose, IV iron, cost minimizatio

Thermal and Mechanical Numerical Modeling of Extrusion-based 3d Printed Reinforced Polymers for Selecting Manufacturing Process Parameters

Extrusion-based 3D printing of thermoplastic polymer composites manufactures parts that have nonhomogenous, orthotropic, and process-dependent macro-scale material properties. As a part of the dissertation, research works were carried out to: • improve the interlayer mechanical properties and reduce the orthotropy, • use experimentally homogenized orthotropic material properties to numerically model the mechanical behavior of the non-homogenous orthotropic 3D printed parts, • create an efficient numerical thermal model to predict the process-dependent thermal history of the 3D printed part, and • aid the manufacturing process by selecting a suitable set of processing parameters based on a simplified sequentially coupled thermomechanical model. The dissertation presents four studies that improve the understanding of the mechanical behavior and aid the manufacturing process of the 3D printed thermoplastic polymer composites. Three journal publications that resulted from the research work carried out are listed below: • Bhandari, S., Lopez-Anido, R. A., & Gardner, D. J. (2019). Enhancing the interlayer tensile strength of 3D printed short carbon fiber reinforced PETG and PLA composites via annealing. Additive Manufacturing, 30, 100922. iii • Bhandari, S., Lopez-Anido, R.A., Wang, L. et al. (2020). Elasto-Plastic Finite Element Modeling of Short Carbon Fiber Reinforced 3D Printed Acrylonitrile Butadiene Styrene Composites. JOM 72, 475– 484. • Bhandari, S.; Lopez-Anido, R.A. (2020). Discrete-Event Simulation Thermal Model for Extrusion-Based Additive Manufacturing of PLA and ABS. Materials, 13, 4985

Aberrant positioning of a central venous dialysis catheter to reveal a left-sided partial anomalous pulmonary venous connection

We describe the identification of a rare, left-sided, partial anomalous pulmonary venous connection during routine central venous catheterization. To our knowledge, this is the first report in the literature to describe this anomaly in a hemodialysis patient. A young man had anomalous connection of the veins draining the upper lobe of the left lung and left innominate vein. Our case demonstrates the importance of routine fluoroscopy during insertion of central venous catheters to detect these anomalies and minimize complications

A mixed-method feasibility study of a novel transitional regime of incremental haemodialysis: study design and protocol

Background: Incremental haemodialysis/haemodiafiltration (HD) may help reduce early mortality rates in patients starting HD. This mixed-method feasibility study aims to test the acceptability, tolerance and safety of a novel incremental HD regime, and to study its impact on parameters of patient wellbeing. Method: We aim to enrol 20 patients who will commence HD twice-weekly with progressive increases in duration and frequency, achieving conventional treatment times over 15weeks (incremental group). Participants will be followed-up for 6months and will undergo regular tests including urine collections, bio-impedance analyses and quality-of-life questionnaires. Semi-structured interviews will be conducted to explore patients’ prior expectations from HD, their motivations for participation and experiences of receiving incremental HD. For comparison of safety and indicators of dialysis adequacy, a cohort of 40 matched patients who previously received conventional HD will be constructed from local dialysis records (historical controls). Results: Data will be recorded on the numbers screened and proportions consented and completing the study (primary outcome). Incremental and conventional groups will be compared in terms of differences in blood pressure control, interdialytic weight changes, indicators of dialysis adequacy and differences in adverse and serious adverse events. In analyses restricted to incremental group, measurements of RRF, fluid load and quality-of-life during follow-up will be compared with baseline values. From patient interviews, a narrative description of key themes along with anonymised quotes will be presented. Conclusion: Results from this study will address a significant knowledge gap in the prescription HD therapy and inform the development novel future therapy regimens

A modified energy detection based dynamic spectrum sharing technique and its real time implementation on wireless platform for cognitive radio networks

Cognitive radio offers a flexible and efficient utilization of radio frequency resources by dynamic spectrum sharing as required in next gen (5G) architecture of wireless communication. The channel allocation time, probability of false alarm detection and spectral efficiency are the major performance parameters to characterize a spectrum sharing technique. This paper presents modified energy detection based dynamic channel allocation technique based on sensing the power spectral density of idle spectrum bands i.e. spectrum hole. Receiver operating characteristics (ROC) curves have been used to analyze the detector performance of sensing with respect to probability false alarm at different values of SNR. Allocation of unoccupied bands to the SUs has been done by coalition based cooperative game, which provides SUs with an incentive to cooperate. Based on their worth, SUs get payoffs which have been computed using Shapely values as a one-point solution. Vickrey–Clarke–Groves (VCG) auction mechanism has been used to allocate the spectrum resources fairly to each user. On the basis of allocation time, the present model for dynamic spectrum access appears to be more efficient as compared to the conventional opportunistic spectrum access model

A modified energy detection based dynamic spectrum sharing technique and its real time implementation on wireless platform for cognitive radio networks

1043-1052Cognitive radio offers a flexible and efficient utilization of radio frequency resources by dynamic spectrum sharing as required in next gen (5G) architecture of wireless communication. The channel allocation time, probability of false alarm detection and spectral efficiency are the major performance parameters to characterize a spectrum sharing technique. This paper presents modified energy detection based dynamic channel allocation technique based on sensing the power spectral density of idle spectrum bands i.e. spectrum hole. Receiver operating characteristics (ROC) curves have been used to analyze the detector performance of sensing with respect to probability false alarm at different values of SNR. Allocation of unoccupied bands to the SUs has been done by coalition based cooperative game, which provides SUs with an incentive to cooperate. Based on their worth, SUs get payoffs which have been computed using Shapely values as a one-point solution. Vickrey–Clarke–Groves (VCG) auction mechanism has been used to allocate the spectrum resources fairly to each user. On the basis of allocation time, the present model for dynamic spectrum access appears to be more efficient as compared to the conventional opportunistic spectrum access model

Breast-feeding status alters the effect of vitamin A treatment during acute diarrhea in children

Vitamin A administration in children reduces the incidence of severe diarrhea during the subsequent few months. We therefore examined the effect of treatment with vitamin A during acute diarrhea on the episode duration and severity. In a double-blind controlled field trial, 900 children 1 to 5 y of age with acute diarrhea of ≤ 7 d duration were randomly assigned to receive vitamin A (60 mg) or a placebo. Children were followed up at home every alternate day until they recovered from the diarrheal episode. In all study children, those treated with vitamin A had a significantly lower risk of persistent diarrhea [odds ratio (OR) 0.30, 95% confidence interval (CI) 0.07-0.97], but there was no effect on the mean diarrheal duration or the mean stool frequency. In the subgroup of children who were not breast-fed, the mean diarrheal duration [ratio of geometric means (GM) 0.84, 95% CI 0.72-0.97], mean number of stools passed after the intervention (ratio of GM 0.73, 95% CI 0.56-0.95), the proportion of episodes lasting ≥ 14 d (P = 0.002) and the percentage of children who passed watery stools on any study day (OR 0.40, 95% CI 0.21-0.77) were significantly lower in those treated with vitamin A. We conclude that administration of vitamin A during acute diarrhea may reduce the severity of the episode and the risk of persistent diarrhea in non-breast-fed children. Similar benefit was not seen in breast-fed children