In vivo biocompatibility evaluation of composite polymeric materials for use in a novel artificial heart valve

A novel trileaflet polymer valve is a composite design of a biostable polymer poly(styrene-isobutylene-styrene) (SIBS) with a reinforcement polyethylene terephthalate (PET) fabric. Surface roughness and hydrophilicity vary with fabrication methods and influence leaflet biocompatibility. The purpose of this study was to investigate the biocompatibility of this composite material using both small animal (nonfunctional mode) and large animal (functional mode) models. Composite samples were manufactured using dip coating and solvent casting with different coating thickness (251μm and 50μm). Sample's surface was characterized through qualitative SEM observation and quantitative surface roughness analysis. A novel rat abdominal aorta model was developed to test the composite samples in a similar pulsatile flow condition as its intended use. The sample's tissue response was characterized by histological examination. Among the samples tested, the 25μm solvent-cast sample exhibited the smoothest surface and best biocompatibility in terms of tissue capsulation thickness, and was chosen as the method for fabrication of the SIBS valve. Phosphocholine was used to create a hydrophilic surface on selected composite samples, which resulted in improved blood compatibility. Four SIBS valves (two with phosphocholine modification) were implanted into sheep. Echocardiography, blood chemistry, and system pathology were conducted to evaluate the valve's performance and biocompatibility. No adverse response was identified following implantation. The average survival time was 76 days, and one sheep with the phosphocholine modified valve passed the FDA minimum requirement of 140 days with approximately 20 million cycles of valve activity. The explanted valves were observed under the aid of a dissection microscope, and evaluated via histology, SEM and X-ray. Surface cracks and calcified tissue deposition were found on the leaflets. In conclusion, we demonstrated the applicability of using a new rat abdominal aorta model for biocompatibility assessment of polymeric materials. A smooth and complete coating surface is essential for the biocompatibility of PET/SIBS composite, and surface modification using phosphocholine improves blood compatibility. Extrinsic calcification was identified on the leaflets and was associated with regions of surface cracks.

An Investigation on Biocompatibility of Bio-Absorbable Polymer Coated Magnesium Alloys

Advances in biomaterials have enabled medical practitioners to replace diseased body parts or to assist in the healing process. In situations where a permanent biomaterial implant is used for a temporary application, additional surgeries are required to remove these implants once the healing process is complete, which increases medical costs and patient morbidity. Bio-absorbable materials dissolve and are metabolized by the body after the healing process is complete thereby negating additional surgeries for removal of implants. Magnesium alloys as novel bio-absorbable biomaterials, have attracted great attention recently because of their good mechanical properties, biocompatibility and corrosion rate in physiological environments. However, usage of Mg as biodegradable implant has been limited by its poor corrosion resistance in the physiological solutions. An optimal biodegradable implant must initially have slow degradation to ensure total mechanical integrity then degrade over time as the tissue heals. The current research focuses on surface modification of Mg alloy (MZC) by surface treatment and polymer coating in an effort to enhance the corrosion rate and biocompatibility. It is envisaged that the results obtained from this investigation would provide the academic community with insights for the utilization of bio-absorbable implants particularly for patients suffering from atherosclerosis. The alloying elements used in this study are zinc and calcium both of which are essential minerals in the human metabolic and healing processes. A hydrophobic biodegradable co-polymer, polyglycolic-co-caprolactone (PGCL), was used to coat the surface treated MZC to retard the initial degradation rate. Two surface treatments were selected: (a) acid etching and (b) anodization to produce different surface morphologies, roughness, surface energy, chemistry and hydrophobicity that are pivotal for PGCL adhesion onto the MZC. Additionally, analyses of biodegradation, biocompatibility, and mechanical integrity were performed in order to investigate the optimum surface modification process, suitable for biomaterial implants. The study concluded that anodization created better adhesion between the MZC and PGCL coating. Furthermore, PGCL coated anodized MZC exhibited lower corrosion rate, good mechanical integrity, and better biocompatibility as compared with acid etched.

The effects of bilingual and monolingual reading videos on story recall with students who are deaf and hard of hearing

The purpose of this study is to investigate the effects of bilingual and monolingual videos on the reading comprehension of students with significant hearing impairments and/or deafness. Children with and without hearing losses need reading programs in which comprehension of meaning is the primary goal. This can occur only when print is represented in meaningful context, allowing children to create meaning from their own experience, background, and knowledge of language.^ Investigated in this study was whether students with significant hearing losses comprehended more information in a bilingual or monolingual instructional video format. There were three instructional videos produced: (a) the bilingual video which incorporated American Sign Language (ASL) with standard English captions, (b) a monolingual English video with standard English captions only, and (c) a monolingual ASL-only video. It was hypothesized that the effects of English captioning with ASL might serve as a bridge during instruction, increasing reading comprehension and written English for students. It was further hypothesized that this would allow students to integrate their own ASL knowledge to the printed text to construct meaning.^ Four separate analyses were conducted to see if the hypothesis was supported by the findings. However, all results indicated that there were no significant differences in students' written measures of reading comprehension recall across any of the three presentations of information (two monolingual and one bilingual condition). There were seven variables (word identification, word recall, sentence recall, story recall, written passage theme, written passage word count, and number of mature words) used to evaluate reading comprehension recall. No variable, either individually or grouped, demonstrated a significant difference between monolingual or bilingual instruction. ^

Hydroxyapatite-nanotube composites and coatings for orthopedic applications

Hydroxyapatite (HA) has received wide attention in orthopedics, due to its biocompatibility and osseointegration ability. Despite these advantages, the brittle nature and low fracture toughness of HA often results in rapid wear and premature fracture of implant. Hence, there is a need to improve the fracture toughness and wear resistance of HA without compromising its biocompatibility. ^ The aim of the current research is to explore the potential of nanotubes as reinforcement to HA for orthopedic implants. HA- 4 wt.% carbon nanotube (CNT) composites and coatings are synthesized by spark plasma sintering and plasma spraying respectively, and investigated for their mechanical, tribological and biological behavior. CNT reinforcement improves the fracture toughness (>90%) and wear resistance (>66%) of HA for coating and free standing composites. CNTs have demonstrated a positive influence on the proliferation, differentiation and matrix mineralization activities of osteoblasts, during in-vitro biocompatibility studies. In-vivo exposure of HA-CNT coated titanium implant in animal model (rat) shows excellent histocompatibility and neobone integration on the implant surface. The improved osseointegration due to presence of CNTs in HA is quantified by the adhesion strength measurement of single osteoblast using nano-scratch technique. ^ Considering the ongoing debate about cytotoxicity of CNTs in the literature, the present study also suggests boron nitride nanotube (BNNT) as an alternative reinforcement. BNNT with the similar elastic modulus and strength as CNT, were added to HA. The resulting composite having 4 wt.% BNNTs improved the fracture toughness (∼85%) and wear resistance (∼75%) of HA in the similar range as HA-CNT composites. BNNTs were found to be non-cytotoxic for osteoblasts and macrophages. In-vitro evaluation shows positive role of BNNT in osteoblast proliferation and viability. Apatite formability of BNNT surface in ∼4 days establishes its osseointegration ability.^

Fat Absorption in Commercial French Fries Depending on Oil Type and Coating

This study examines the effect of edible coatings, type of oil used, and cooking method on the fat content of commercially available French fries. In contrast to earlier studies that examined laboratory prepared French fries, this study assesses commercially available French fries and cooking oils. This study also measured the fat content in oven baked French fries, comparing the two cooking methods in addition to the comparisons of different coatings’ oil uptake. The findings of this study were that the type of oil used did have a significant impact on the final oil content of the uncoated and seasoned fries. The fries coated in modified food starch and fried in peanut and soy oils had what appeared to be significantly higher oil content than those fried in corn oil or baked, but the difference was not statistically significant. Additionally, fat content in French fries with hydrocollidial coatings that were prepared in corn oil were not significantly different than French fries with the same coating that were baked.

Effects of real -time captioning and sign language interpreting on the learning of college students who are deaf or hard of hearing

College personnel are required to provide accommodations for students who are deaf and hard of hearing (D/HoH), but few empirical studies have been conducted on D/HoH students as they learn under the various accommodation conditions (sign language interpreting, SLI, real-time captioning, RTC, and both). Guided by the experiences of students who are D/HoH at Miami-Dade College (MDC) who requested RTC in addition to SLI as accommodations, the researcher adopted Merten’s transformative-emancipatory theoretical framework that values perceptions and voice of students who are D/HoH. A mixed methods design addressed two research questions: Did student learning differ for each accommodation? What did students experience while learning through accommodations? Participants included 30 students who were D/HoH (60% women). They represented MDC’s majority minority population: 10% White (non-Hispanic), 20% Black (non-Hispanic, including Haitian/Caribbean), 67% Hispanic, and 3% other. Hearing loss, ranged from severe-profound (70%) to mild-moderate (30%). All were able to communicate with American Sign Language: Learning was measured while students who were D/HoH viewed three lectures under three accommodation conditions (SLI, RTC, SLI+RTC). The learning measure was defined as the difference in pre- and post-test scores on tests of the content presented in the lectures. Using repeated measure ANOVA and ANCOVA, confounding variables of fluency in American Sign Language and literacy skills were treated as covariates. Perceptions were obtained through interviews and verbal protocol analysis that were signed, videotaped, transcribed, coded, and examined for common themes and metacognitive strategies. No statistically significant differences were found among the three accommodations on the learning measure. Students who were D/HoH expressed thoughts about five different aspects of their learning while they viewed lectures: (a) comprehending the information, (b) feeling a part of the classroom environment, (c) past experiences with an accommodation, (d) individual preferences for an accommodation, (e) suggestions for improving an accommodation. They exhibited three metacognitive strategies: (a) constructing knowledge, (b) monitoring comprehension, and (c) evaluating information. No patterns were found in the types of metacognitive strategies used for any particular accommodation. The researcher offers recommendations for flexible applications of the standard accommodations used with students who are D/HoH.

Prisons, Profits, and Hard Labor: A Brief History of Convict Labor In Florida

The purpose of this research is to develop a broader understanding of the system in Florida. Specifically, I am looking at the privatization of convict labor programs by the Prison Rehabilitative Industries and Diversified Enterprises Corporation (PRIDE) in the 1980s and 1990s in state correctional institutions. This research will contribute to historiography of prisons in Florida in the context of the developing research about the Prison-Industrial Complex. Many scholars studying the Prison-Industrial Complex have drawn comparisons to today’s prison industries and the convict lease system of the late 19th and early 20th centuries, seeing the prison system go full circle drawing attention to the exploitative and institutionally racist nature of the modern prison system. This researched showed that the trend other scholars have studied also exist in Florida and Florida was actually a pioneer in the Prison-Industrial Complex. It was the first state to privatize its convict labor programs, becoming a model for other states. This research also shows that political and economic motivations were the primary forces governing prison policies, rather than education, rehabilitation, and safety. To complete this project, I analyzed articles from South Florida newspapers, such as the Sun-Sentinel and the Miami Herald, published during this period as well as literature published by the Department of Corrections. The United States has the highest rate of incarceration in the world and spends more money on prisons than education. Being such a large part of country, prisons warrant more critical study. This research will shed light on the nature of prisons, specifically here in Florida, in the hopes of seeking alternatives.

Prisons, Profits, and Hard Labor: A Brief History of Convict Labor In Florida

The purpose of this research is to develop a broader understanding of the system in Florida. Specifically, I am looking at the privatization of convict labor programs by the Prison Rehabilitative Industries and Diversified Enterprises Corporation (PRIDE) in the 1980s and 1990s in state correctional institutions. This research will contribute to historiography of prisons in Florida in the context of the developing research about the Prison-Industrial Complex. Many scholars studying the Prison-Industrial Complex have drawn comparisons to today’s prison industries and the convict lease system of the late 19th and early 20th centuries, seeing the prison system go full circle drawing attention to the exploitative and institutionally racist nature of the modern prison system. This researched showed that the trend other scholars have studied also exist in Florida and Florida was actually a pioneer in the Prison-Industrial Complex. It was the first state to privatize its convict labor programs, becoming a model for other states. This research also shows that political and economic motivations were the primary forces governing prison policies, rather than education, rehabilitation, and safety. To complete this project, I analyzed articles from South Florida newspapers, such as the Sun-Sentinel and the Miami Herald, published during this period as well as literature published by the Department of Corrections. The United States has the highest rate of incarceration in the world and spends more money on prisons than education. Being such a large part of country, prisons warrant more critical study. This research will shed light on the nature of prisons, specifically here in Florida, in the hopes of seeking alternatives.