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Poly (Vinylidene Fluoride): Crystalline structure, morphology, and conversation to exotic carbon nanomaterials
No full textVery few polymers offer the same fundamental scientific intrigue, real life application usefulness, and overall versatility as Poly (Vinylidene Fluoride) (PVDF). Though PVDF has been extensively studied, as a whole, over the past 50 years, majority of the research has centered on understanding the fascinating piezoelectric effects of PVDF and the polar beta phase conformation that results in such previously mentioned effects. Beyond its pyro- ferro- and piezoelectric properties, PVDF also offers much usefulness in the realms of chemically inert membrane materials and as a carbon precursor material. To date there fails to exist a definitive reference for the processing effects and crystalline characteristics of PVDF. In order to take the next step in fully understanding this system we must complement the current published literature with accurate and comprehensive morphological information pertaining to the many lamellar structures of PVDF which had only been theorized into existence to date. Secondarily, the use of PVDF as a viable carbon precursor material is also an understudied regime. These studies have mostly been limited in scope to carbon fiber-based materials and film applications. Here we aim to demonstrate an even greater value in the use of PVDF as a precursor material for the synthesis of unique and exotic template carbon nanomaterials. This thesis proposal shall attempt to define and characterize the free standing morphological differences in the previously documented polymorphic structures of PVDF, to produce the first processing-structure-properties phase diagram for PVDF, and to demonstrate the ability to utilize PVDF as a carbon precursor material while maintaining its unique and highly tailorable morphological structure throughout. These things in turn will provide a greater vantage point towards our comprehensive understanding of the PVDF crystallization phenomena and processing behavior.Ph.D., Materials Science and Engineering -- Drexel University, 201
A Phenomenological Study: Exploring College Students' Experiences and Perceptions About Their Adjuncts' Teaching Styles
No full textThe purpose of this qualitative study using the phenomenological approach was to explore students' lived experiences through their perceptions of the effectiveness of adjuncts' teaching styles in one community college located in the Northeastern United States. Many adjuncts bring knowledge of their field and passion to their learning spaces, but they lack the teaching skills to communicate their knowledge to their students effectively. Through the critical student experience, this study explored adjuncts' teaching styles. This study used the interview method to explore how college students describe how they learn most effectively, the teaching styles their adjunct instructors use in the classroom, and how they characterize an effective adjunct. A three-part one-on-one, semi-structured interview was used to collect data from five college students about their experiences with adjuncts' teaching skills. The data was analyzed for common themes that emerged from the college students' experiences with adjuncts' teaching styles providing five results. First, students perceive real world application methods to be an effective learning and teaching style they experienced with adjuncts. Second, Students perceive content knowledge to be a characteristic of effective adjunct teaching that they have experienced with adjuncts. Third, students perceive communication to be a characteristic of effective learning and teaching styles, however they have experienced communication barriers with adjuncts. Fourth, students perceive student-focused and varied teaching approaches to be effective learning and teaching styles, however they describe their experiences as being instructor-focused. Fifth, while students have experienced both adaptable and one size fits all teaching styles they favor the adaptable approach to teaching. Recommendations for further research from the student perspective include exploring teaching styles of adjuncts of specific academic programs and at four year institutions as well as full time professors will provide context for this study.Ed.D., Educational Leadership and Management -- Drexel University, 201
African American Weight Loss Experiences from the Perspective of Past Treatment Participants
No full textCompared to other racial-ethnic groups, African Americans are disproportionately impacted by the obesity epidemic, with this population presenting the highest rates of obesity. Additionally, behavioral weight loss interventions produce significantly lower weight losses among African American participants (Cox et al., 2013). The current study collected qualitative data from African American participants who completed a clinical trial, Project ENACT, which compared standard and acceptance-based behavioral weight loss treatments (Butryn et al., 2017). Focus groups were utilized to address three main aims: 1) identify the emotional, mental and environmental influences that African American participants perceived to be most important for their weight control; 2) identify the extent to which African American participants identify unique racial-ethnic and cultural factors as influences on their weight control; 3) explore how perceived treatment value, effectiveness and areas for improvement may differ in participants who did versus those who did not receive acceptance-based skills training. Four focus groups were conducted with African American men and women (n =24) who had completed the ENACT program. Major themes from participant responses map onto the following categories: universal barriers to health; general facilitation to health; barriers to healthy living related to the African American experience; suggestions for treatment improvement; and treatment facilitation. Results from this study could inform future weight loss intervention development and education by uncovering weight loss barriers tied to the unique cultural and emotional experiences of African Americans attempting to lose weight, while also ascertaining how acceptance-based treatments might address these unique barriers.M.S., Psychology -- Drexel University, 201
Business model: A study of six small start-up nonprofit arts and cultural organizations
No full textThis thesis explores the understanding of the business model in six small start-up nonprofit arts and cultural organizations and identifies strategies the organizations applied to build and develop each component of a business model. Case studies of the organizations showed that there are misunderstandings and incomplete understandings toward a business model in the nonprofit sector. Although all organizations missed a specific component of a comprehensive business model, they all regarded the business model as a useful management tool to guide different aspects of their organizations. Since all organizations are still in the start-up life stage, the development of a business model has not shown a significant effect on organizational operation and programming. Moreover, there remain gaps between theoretical analysis of a business model and management reality among the nonprofit organizations. Each organization has designed and utilized strategies to particular components in a business model, and they have achieved various outcomes in practice in the first of a couple of years after establishment due to the utilization of the business model and corresponding strategies. This paper aims to provide practical and real examples in the nonprofit sector to present useful strategies and business model practice among small start-up arts and cultural organizations for emerging organizations to learn from and get inspirations.M.S., Arts Administration -- Drexel University, 201
Evaluating the Use of S. pasteurii on Mitigating the Damage Response of Cementitious Materials Exposed to Calcium Chloride
No full textDeterioration of concrete pavements in the United States has increased over the past decade and is becoming a common occurrence. This damage is triggered by two possibilities: classic freeze-thaw behavior, as well as the formation of calcium oxychloride from a reaction between calcium hydroxide in the concrete and chloride-based deicing salts. Calcium oxychloride (CAOXY) is an expansive phase that may lead to significant damage in the cementitious matrix and result in cracking. This study investigates the use of alkaliphilic, spore-forming bacteria to mitigate the formation of calcium oxychloride. Mortar and paste samples were made with ordinary portland cement; ordinary portland cement combined with nutrients; and ordinary portland cement combined with bacteria and nutrients. Low-temperature differential scanning calorimetry (LT-DSC), thermogravimetric analysis (TGA), sorption analyzer (SA), and acoustic emissions (AE) were used to quantify the amount of calcium oxychloride, calcium hydroxide, microstructural change, and damage caused by CaCl2 salt in the cementitious samples, respectively. It was shown that the addition of bacteria significantly reduces the formation of CAOXY in the cementitious matrix. The bacteria were shown to utilize not only calcium hydroxide from cement hydration products, but also calcium chloride salt solution as sources to produce microbial induced calcium carbonate, thereby lowering the formation of CAOXY. This resulted in reductions in both calcium hydroxide and calcium chloride and an increase in the amount of calcium carbonate precipitated in the microstructure of cementitious materials. As a result, damage created due to CAOXY was substantially mitigated in the bacteria samples when exposed to calcium chloride deicing salt. It was also found that the addition of bacteria to cementitious system created a change in the micropore structure and pore size distribution of cement paste.M.S., Civil Engineering -- Drexel University, 201
Self-Disclosure and Response Behaviors in Socially Stigmatized Contexts on Social Media
No full textSocial computing platforms are often celebrated for their capacity to connect; yet expressing one's identity, and seeking as well as providing support on these platforms can be difficult when people experience distress and stigma. In this dissertation, I theorize social media behaviors such as sensitive disclosures and interactions around them. I address how we can design social computing systems that facilitate disclosures of difficult and stigmatized human experiences and enable supportive interactions to form around them. I focus on pregnancy loss, as a common reproductive health experience that is often traumatizing and not disclosed in spite of potential disclosure benefits such as access to social support. First, I contribute a framework to explain direct pregnancy loss disclosures and non-disclosures on social media. I conducted in-depth phenomenological interviews with women in the U.S. who are social media users and had experienced pregnancy loss within the past two years. This framework includes six types of decision factors related to the self, audience, network, society, affordances and platform, and time. I also introduce the novel concept of network-level reciprocal disclosure to describe broadcast disclosures that happen in response to and in anticipation of others' disclosures and a perceived reduction in stigma. Second, I contribute a typology of indirect disclosure strategies and an understanding of decision factors informing indirect disclosures of sensitive experiences across social media platforms. Indirect disclosure strategies include hinting about an experience or an identity facet in such a way that the audience must infer the full message, or explicitly sharing information through another person. Factors related to the self, audience and affordances, and time motivate individuals to disclose pregnancy loss in an indirect manner, although in distinct ways compared to direct disclosures. Finally, responses to sensitive disclosures are important to understand if we aim to design social computing systems that encourage supportive interactions. I used interviews and designed vignette instruments to provide a response decision making framework (RDM) that explains factors informing whether and how individuals respond to sensitive disclosures from their social media connections. This framework includes factors related to the self, poster, and disclosure context. I identify empirically grounded design and research implications to support potential disclosers and responders in sensitive or stigmatized contexts on social media.Ph.D., Information Studies -- Drexel University, 201
Bone Mineral Density, Body Composition and Dietary Intake in Asian Indian and Caucasian Males
Get PDFBackground: The difference in osteoporotic fractures across different ethnic groups could be due to the differences in body composition and eating habits. The variation in areal bone mineral density (aBMD), body composition and dietary intake between immigrant Asian Indians and Caucasians are unknown. Objective: The objective of this study was to examine the differences in aBMD, body composition and dietary intake between immigrant Asian Indians and Caucasians matched for age and body mass index (BMI). Also, we examined the relationship between body composition and aBMD and how might the relationships differ between the two groups. Design: A convenient sample of 32 healthy males who self-identified themselves as either Asian Indians (n=16) or Caucasians (n=16) were recruited for this cross-sectional study. Dual-energy x-ray absorptiometry (DXA) was used for measuring aBMD and bone mineral content (BMC) at the lumbar spine, femoral neck, 33% radius of the non-dominant hand and whole body. Body composition was measured using whole body scan by DXA. Dietary intake was assessed using 24-hour food recall and food frequency questionnaires. Results: There was no difference between groups in age and BMI. Lean mass was lower in Asian Indians compared Caucasians (p=0.03). aBMD at measured sites were similar between two groups (all p>0.05). However, BMC was lower at all skeletal sites (all p0.05). There were no differences in the correlation between body composition with aBMD between Asian Indians and Caucasians. Regarding dietary intake, calcium and magnesium intakes were not different between the two ethnic groups (all p<0.05). Conclusion: Asian Indian men have lower lean mass and BMC at different skeletal sites, but similar other body composition variables and dietary intakes compared to age and BMI matched Caucasians. Lean mass showed a positive correlation with aBMD. Since the scope of this study was limited to examine the difference in bone density using aBMD, the study highlights the need for further research to examine the variability in bone turnover between immigrant Asian Indians and Caucasians to see if the findings from biochemical properties and bone density are similar.M.S., Nutrition Sciences -- Drexel University, 201
Atttachment-Based Family Therapy, Changes in Parental Validation and Adolescent Symptoms in a Diverse Sample of Suicidal Teens and Parents
No full textAdolescent suicide is a significant public health problem in the United States. Suicide is the third leading cause of death among adolescents aged 10-14 and the second among persons aged 15-34 (CDC, 2015). High family conflict and stress and low family cohesion have been linked with teen suicide risk, while emotionally supportive family processes such as parental warmth, talking openly about emotions and parental validation are associated with reduced risk. This study will examine therapeutic change processes in a sample of ethnically diverse teens with high levels of suicide ideation and their parents who received sixteen weeks of treatment with Attachment Based Family Therapy. We will examine: (1) whether participating parents show a significant increase in supportive parenting over the course of therapy through analyses of observational codes of parent-teen interactions during family sessions and; (2) whether increases in supportive parenting are associated with symptoms improvement in teens.Ph.D., Couple and Family Therapy -- Drexel University, 201
Microtubule-mediated nerve regeneration: Knocking down the microtubule severing protein fidgetin augments nerve regeneration in vitro and in vivo
No full textThe purpose of this thesis was to explore the effects of fidgetin knockdown in adult dorsal root ganglia both in vitro and in vivo. Our lab has demonstrated that fidgetin knockdown in embryonic cortical neurons increased microtubule mass and axon length. It is known that microtubules are paramount for axon growth and an effect that increases their mass and axon length is attractive as a potential regenerative target. Adult dorsal root ganglia were utilized because they are the only adult neuron capable of being cultured in a dish and they are relevant to nerve regeneration both within the peripheral and central nervous system. The adult dorsal root crush rodent injury model was used as the complementary in vivo system. In the coming pages, I describe why microtubules are essential to neurons and attractive therapeutic targets. Microtubules are paramount for nerve regeneration and the discovery of novel microtubule associated proteins, small molecules that bind tubulin to affect its stability properties, and the expansion of the tubulin code all has the potential to reveal novel therapeutic targets for regeneration. The remaining chapters describe how fidgetin knockdown in adult dorsal root ganglia neurons, in vitro, increases a specific domain of microtubule mass responsible for expanding microtubules, increases the length of axons on and off the inhibitory spots, and promotes cellular growth on and across the inhibitory spots. Finally, I conclude with our promising in vivo results that fidgetin augments nerve regeneration in vivo, thus highlighting fidgetin as a novel therapeutic target to augment nerve regeneration. Furthermore, my work serves as a "plug-and-play" system for future investigations of microtubule-based therapies and combinatorial treatments such as chondroitinase, growth factors, and other viral transductions.Ph.D., Molecular and Cell Biology and Genetics -- Drexel University, 201
Purification and characterization of a Kaposi’s sarcoma-associated herpesvirus latency-associated nuclear antigen DNA-binding domain mutant
No full textKaposi's sarcoma-associated herpesvirus (KSHV) infection is associated with three human malignancies: Kaposi’s sarcoma (KS), primary effusion lymphoma (PEL), and Multicentric Castleman’s disease (MCD). Latency-associated nuclear antigen (LANA) is one of the few viral proteins expressed during latent KSHV infection. It acts as the master regulator of KSHV latency and is essential for viral replication and episome maintenance. Previous studies have shown that these functions are promoted by oligomerization of LANA, which is a process mediated by the DNA-binding domain (DBD). The structure of the wild-type LANADBD forms higher-order oligomers upon crystallization, which poses a challenge to characterizing the DBD. Mutations within the dimer-dimer interface of LANA, specifically at residues F1037 and F1041, disrupt higher-order oligomerization. Crystallization of lower-order oligomers could improve resolution of the DBD. Given this, we sought to purify and crystallize the LANA DBD F1037A/F1041A double mutant (LANA,DBD,AA). Bacterial expression of LANADBD,AA was optimized by varying IPTG concentration, the duration of IPTG induction, and the induction temperature. Multiple methods of protein purification were utilized, including batch affinity purification, affinity column chromatography and ion-exchange column chromatography. Purified LANA,DBD,AA was subjected to a variety of crystallization conditions. These conditions included attempts to optimize buffer pH, %PEG, and molecular weight of PEG. Future directions will focus on determining the structure of LANA,DBD,AA, as well as the structures of the single mutants F1037A (LANA,DBD,AF) and F1041 (LANA,DBD,FA). These mutant structures will aid in the design and development of a small molecule that inhibits LANA-DNA binding.M.S., Cancer Biology -- Drexel University, 201