Photolithographic micropatterning of organic, flexible biomaterials and its applications

A current trend in biodevices has involved a shift from traditional rigid platforms to flexible and stretchable formats. These flexible devices are expected to have a significant impact on future healthcare, disease diagnostics and therapeutics. However, the fabrication of such flexible devices has been limited by the choice of materials. Biomimetic composites of naturally derived and synthetic polymers provide exciting opportunities to develop mechanically flexible, physiologically compliant, and degradable bioelectronic systems. Advantages include the ability to provide conformal contact at non-planar biointerfaces, being able to be degraded at controllable rate, and invoking minimal reactions within the body. These factors present great potential as implantable devices for in-vivo applications, while also addressing concerns with “electronic waste” by being intrinsically degradable. In this work, we present a combination of photo-crosslinkable silk proteins and conductive polymers to precisely fabricate flexible devices and cell culture substrate. A facile and scalable photolithography is applied to fabricate flexible substrates with conductive and non- conductive micropatterns which show tuneable electrical and mechanical properties. We also demonstrate an approach to engineer flexibility in materials through the creation of patterned defects inspired from Kirigami- the Japanese art of paper cutting. Mechanically flexible, free- standing, optically transparent, large-area biomaterial sheets with precisely defined and computationally designed microscale cuts can be formed using a single-step photolithographic process. As composites with conducting polymers, flexible, intrinsically electroactive sheets can be formed. Through this work, the possibility of making next- generation, fully organic, flexible bioelectronics is explored.https://scholarscompass.vcu.edu/gradposters/1099/thumbnail.jp

Transport in Ultra-Thin Heat Pipes for Low Power Applications

Heat pipes and vapor chamber heat spreaders offer a potential solution to the increasing thermal management challenges in thin-form-factor mobile computing platforms, where efficient spreading is required to simultaneously prevent overheating of internal components and formation of hot regions on the device exterior surfaces. The operating conditions for such applications are also characterized by low input heat fluxes, which in combination with the geometric constraints, give rise to unique performance limitations that require examination. This thesis aims to characterize the steady-state and transient heat pipe performance limitations unique to such ultra-thin form factors, and characterizes the key heat transfer mechanisms governing the performance. A thermal resistance network model and a detailed two-dimensional model are used to analyze the steady-state performance of heat pipes under these conditions. A broad parametric study of geometries and heat inputs using the reduced-order model helps delineate the performance thresholds within which the effectiveness of a heat pipe is greater than that of a comparable solid heat spreader. A vapor-phase threshold unique to ultra-thin heat pipes operating at low power inputs is observed. At this threshold, the vapor-phase thermal resistance imposed by the saturation pressure/temperature gradient in the heat pipe causes a crossover in the thermal resistance, where performance becomes worse than a solid heat spreader. The higher-fidelity numerical model is used to assess the accuracy of the thermal resistance network model and to verify the validity and applicability of each assumption made regarding the transport mechanisms. Key heat transfer mechanisms not captured by the reduced-order thermal network models are identified. These include the effect of boundary conditions on the interface mass flux profile, convective effects on the vapor core temperature drop, and two-dimensional conduction on smearing of evaporation/condensation mass flux into the adiabatic section. Lastly, the numerical model was used to compare the transient performance between ultra-thin heat pipes and heat spreaders during the initial start-up period was conducted to demonstrate an initial crossover period under which the performance of the heat pipe was lower than that of a heat spreader. This thesis establishes the performance thresholds of ultra-thin form factor heat pipes operating at low input heat fluxes under steady-state operation, and identifies key performance traits that must be considered under transient operation

U.S. school quality: The public benefits of primary and secondary education

Three essays focus on the various measurements of school quality and its importance in motivating people\u27s location choices, their interest in school improvement, and their ability to fund additional school expenditures. The first essay examines hedonic housing price studies to dissect the mixed evidence on whether school quality affects housing prices. The chapter employs meta-regression analysis on 48 studies and finds that studies which measured school quality using any of eight measures, including educational expenditures, tend to find a positive correlation with housing prices. Additionally, published studies tend to find a higher correlation than unpublished studies. The second essay aims to remove the endogeneity bias between educational expenditures and inmigration with generalized propensity score methods. We restrict the study period to 2006–2010 and our focus to the population aged 25–49 years. We find that increases in educational expenditures have a positive effect on inmigration to U.S. counties up to $7,000 but a generally flat effect beyond that. The third essay examines education tax referenda, which school districts propose to taxpayers to attain funding additional to their state-allocated funds. The chapter examines educational finance using sample selection methods to correct for school district decisions to enter the referenda proposal process and finds that few school districts take advantage of educational tax referenda, with rural school districts being more likely to do so than urban school districts. Additionally, the results suggest that racial diversity, competition from private schools and school district size significantly affect proposal and approval of referenda across rural and urban school districts

A prospective study on antibiotic prescribing pattern among in-patients of medicine department of a tertiary care hospital

Background: Irrational prescription is a major contributor to the antimicrobial resistance. Tertiary care centres in a state are the centres of excellence where policies are framed. So, they have an important role in promoting rational antibiotic prescription.Methods: The study was conducted on in-patients of medicine ward in government medical college, Calicut, for a period of 2 months (January to February 2018), The data was collected from IP case records of patients. The parameters checked includes appropriateness of the antibiotic as, to whether it is according to our hospital antibiotic policy, whether de-escalation and change to oral drug was done, whether it is prescribed by generic name, is it given as fixed drug combination (FDC), is it from national list of essential medicine.Results: Among the 135-prescription analyzed, total 225 antibiotics were used. Cephalosporins (32%) were the most commonly used. Of this only 40% was given by generic prescription. 27% was FDCs. 55% was from national list of essential medicines and 69% of them were ‘WATCH’ drug according to WHO Antibiotic Policy. Regarding appropriateness of prescriptions around 56% included right drug, 93% had right dose and frequency, and 70% had right duration and 100% were given through right route.Conclusions: Strict adherence to hospital antibiotic policy and plan for effective teaching programs regarding antibiotic resistance and importance of rational prescription of antibiotics can improve the quality of antibiotic prescription and minimize antibiotic resistance

Morphological study and biochemical characterization of the Alveolate flagellate Colpodella sp. (Apicomplexa) in a diprotist culture with Bodo caudatus

Plasmodium falciparum, the causative agent of severe human malaria shares the presence of apical complex organelles with the free-living predatory alveolate, Colpodella sp. In this study we investigated morphological, biochemical and molecular characteristics of Colpodella sp. in a diprotist culture containing Bodo caudatus as prey. Colpodella attaches to its prey using the apical end. Attachment lasted for approximately 20 minutes while the cytoplasmic contents of the prey were aspirated into the posterior food vacuole of Colpodella in a process known as myzocytosis. Indirect immunofluorescence assay (IFA) using P. falciparum rhoptry specific antibodies showed intense reactivity with cytoplasmic vesicles of Colpodella but not Bodo caudatus. DNA isolated from a pellet of the diprotist culture was used in polymerase chain reaction (PCR) with oligonucleotide primers designed to target the P. falciparum (strains 3D7, DD2, FC27 and FCR8) rhoptry genes Rhop-3, Rhop-1 and RAMA. An approximately 2,906 bp single fragment was amplified from P. falciparum (strains 3D7 and FCR8) and diprotist DNA using RAMA primers. Similarly, DNA fragments of a similar size were amplified from the same DNA templates using primers targeting a highly conserved fragment of the18S rRNA used to identify a colpodellid associated with a human infection. Primers targeting conserved regions of the 18S rRNA of kinetoplastid species amplified a DNA fragment of 650 bp in P. falciparum (strains 3D7, DD2, FC27 and FCR8) and diprotist DNA. In addition, the kinetoplastid primers amplified a second fragment of approximately 2 kb from the diprotist DNA. Primers targeting the P. falciparum Rhop-1 gene amplified a 690 bp DNA fragment in all four P. falciparum strains but amplified a fragment of approximately 2 kb from diprotist DNA. Primers for the P. falciparum Rhop-3 gene target amplified a 660 bp DNA fragment in all four P. falciparum strains while DNA fragments of 2 kb, 800 bp and 500 bp were amplified from the diprotist DNA template. DNA sequence analysis of PCR amplified diprotist DNA identified the Rhop-3 gene demonstrating conservation of the Rhop-3 gene in Colpodella sp.https://engagedscholarship.csuohio.edu/u_poster_2017/1012/thumbnail.jp

Bioinformatic Analysis of the Sodium Hydrogen Exchanger Protein in Plasmodium yoelii

Since its discovery over 100 years ago, malaria has been the most important parasitic disease in the world. Malaria affects about 300 to 500 million people every year; killing 5 million people every year. The most virulent causative agent in humans is Plasmodium falciparum; it is an important member of the phylum Apicomplexa, which also includes Toxoplasma gondii. These organisms contain specialized, unique structures, including rhoptry organelles. In Plasmodium and Toxoplasma gondii, they assist invasion into the host cell. Analyses have been performed on proteins located in rhoptries in Toxoplasma and Plasmodium. Among the proteins that have been analyzed, the sodium hydrogen exchanger protein has been found in these parasites, but not much is known about its characterization and function in Plasmodium. This protein was found to be localized in the rhoptries in Toxoplasma gondii in an experiment performed by Karasov et. al. The protein homologue in T. gondii, TgNHE2, has become the first intracellular sodium hydrogen exchanger (NHE) characterized in a protozoan parasite. Proteome analysis show that there are four NHE2 in T. gondii, but only two are known in the parasite. Comparative analyses including protein sequence alignments were performed showing the relationship of this protein across several species. This protein is found across several species of Apicomplexa and vary widely in size and weight. The four proteins that were analyzed were two strains in P. falciparum (PFIT_1302700 and PF3D7_1303500), P. yoelii (PY02931), and T. gondii (TGME49_105180). The analysis shows regions of similarity in the location of the transmembrane domains amongst PFIT, PF3D7, and PY02931. These species also contain regions of asparagine-, aspartic acid-, and lysine-rich regions that overlap. This protein is also present in mammals, in the mitochondria. It is primarily characterized as an intracellular protein in mammals although it is found in the plasma membrane of certain cells. The characterization of this protein in T. gondii will provide a groundwork in better understanding its function in Plasmodium, specifically P. falciparum.https://engagedscholarship.csuohio.edu/u_poster_2016/1011/thumbnail.jp

Morphological study and biochemical characterization of the Alveolate flagellate Colpodella sp. (Apicomplexa) in a diprotist culture with Bodo caudatus

Plasmodium falciparum, the causative agent of severe human malaria shares the presence of apical complex organelles with the free-living predatory alveolate, Colpodella sp. In this study we investigated morphological, biochemical and molecular characteristics of Colpodella sp. in a diprotist culture containing Bodo caudatus as prey. Colpodella attaches to its prey using the apical end. Attachment lasted for approximately 20 minutes while the cytoplasmic contents of the prey were aspirated into the posterior food vacuole of Colpodella in a process known as myzocytosis. Indirect immunofluorescence assay (IFA) using P. falciparum rhoptry specific antibodies showed intense reactivity with cytoplasmic vesicles of Colpodella but not Bodo caudatus. DNA isolated from a pellet of the diprotist culture was used in polymerase chain reaction (PCR) with oligonucleotide primers designed to target the P. falciparum (strains 3D7, DD2, FC27 and FCR8) rhoptry genes Rhop-3, Rhop-1 and RAMA. An approximately 2,906 bp single fragment was amplified from P. falciparum (strains 3D7 and FCR8) and diprotist DNA using RAMA primers. Similarly, DNA fragments of a similar size were amplified from the same DNA templates using primers targeting a highly conserved fragment of the18S rRNA used to identify a colpodellid associated with a human infection. Primers targeting conserved regions of the 18S rRNA of kinetoplastid species amplified a DNA fragment of 650 bp in P. falciparum (strains 3D7, DD2, FC27 and FCR8) and diprotist DNA. In addition, the kinetoplastid primers amplified a second fragment of approximately 2 kb from the diprotist DNA. Primers targeting the P. falciparum Rhop-1 gene amplified a 690 bp DNA fragment in all four P. falciparum strains but amplified a fragment of approximately 2 kb from diprotist DNA. Primers for the P. falciparum Rhop-3 gene target amplified a 660 bp DNA fragment in all four P. falciparum strains while DNA fragments of 2 kb, 800 bp and 500 bp were amplified from the diprotist DNA template. DNA sequence analysis of PCR amplified diprotist DNA identified the Rhop-3 gene demonstrating conservation of the Rhop-3 gene in Colpodella sp.https://engagedscholarship.csuohio.edu/u_poster_2017/1012/thumbnail.jp

Partial evaluation in an optimizing prolog compiler

Specialization of programs and meta-programs written in high-level languages has been an active area of research for some time. Specialization contributes to improvement in program performance. We begin with a hypothesis that partial evaluation provides a framework for several traditional back-end optimizations. The present work proposes a new compiler back-end optimization technique based on specialization of low-level RISC-like machine code. Partial evaluation is used to specialize the low-level code. Berkeley Abstract Machine (BAM) code generated during compilation of Prolog is used as the candidate low-level language to test the hypothesis. A partial evaluator of BAM code was designed and implemented to demonstrate the proposed optimization technique and to study its design issues. The major contributions of the present work are as follows: It demonstrates a new low-level compiler back-end optimization technique. This technique provides a framework for several conventional optimizations apart from providing opportunity for machine-specific optimizations. It presents a study of various issues and solutions to several problems encountered during design and implementation of a low-level language partial evaluator that is designed to be a back-end phase in a real-world Prolog compiler. We also present an implementation-independent denotational semantics of BAM code--a low-level language. This provides a vehicle for showing the correctness of instruction transformations. We believe this work to provide the first concrete step towards usage of partial evaluation on low-level code as a compiler back-end optimization technique in real-world compilers