Polyamide Nanocomposites for Selective Laser Sintering

Current polyamide 11 and 12 are lacking in fire retardancy and high strength/high heat resistance characteristics for a plethora of finished parts that are desired and required for performance driven applications. It is anticipated that nanomodification of polyamide 11 and 12 will result in enhanced polymer performance, i.e., fire retardancy, high strength and high heat resistance for polyamide 11 and 12. It is expected that these findings will expand the market opportunities for polyamide 11 and 12 resin manufacturers. The objective of this research is to develop improved polyamide 11 and 12 polymers with enhanced flame retardancy, thermal, and mechanical properties for selective laser sintering (SLS) rapid manufacturing (RM). A nanophase was introduced into the polyamide 11 and 12 via twin screw extrusion to provide improved material properties of the polymer blends. Arkema RILSAN® polyamide 11 molding polymer pellets and Degussa VESTAMID® L1670 polyamide 12 were examined with three types of nanoparticles: chemically modified montmorillonite (MMT) organoclays, surface modified nanosilica, and carbon nanofibers (CNFs) to create polyamide 11 and 12 nanocomposites. Wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) were used to determine the degree of dispersion. Injection molded test specimens were fabricated for physical, thermal, mechanical properties, and flammability tests. Thermal stability of these polyamide 11 and 12 nanocomposites was examined by TGA. Mechanical properties such as tensile, flexural, and elongation at break were measured. Flammability properties were also obtained using the Cone Calorimeter at an external heat flux of 50 kW/m2. TEM micrographs, physical, mechanical, and flammability properties are included in the paper. Polyamide 11 and 12 nanocomposites properties are compared with polyamide 11 and 12 baseline polymers. Based on flammability and mechanical material performance, selective polymers including polyamide 11 nanocomposites and control polyamide 11 were cryogenically ground into fine powders and fabricated into SLS parts.Mechanical Engineerin

Supporting requirements model evolution throughout the system life-cycle

Requirements models are essential not just during system implementation, but also to manage system changes post-implementation. Such models should be supported by a requirements model management framework that allows users to create, manage and evolve models of domains, requirements, code and other design-time artifacts along with traceability links between their elements. We propose a comprehensive framework which delineates the operations and elements necessary, and then describe a tool implementation which supports versioning goal models

Economic Justice Monitoring Project

The Central Corridor also known as the Green Line stretching between downtown Minneapolis and downtown St. Paul crossing University of Minnesota covers 11 miles area with many businesses and residential houses. The Green Line is expected to make commuting easier to support the development of the Twin cities. With a long stretch through busy area, the light rail construction is making a big and direct impact on people and businesses. Since the light rail construction took place in early 2012, the businesses along University Ave have encountered many difficulties. Among those businesses, small businesses experience the most impact. The impact is measured not only by how many businesses are open or close but also the revenue, the amount of customers as well as human and social impact. The research picks Little Mekong area to study CCLRT's impacts on small businesses and the owners of those businesses. Little Mekong, a 5 block strip of University Avenue from MacKubin Street to Galtier Street in Saint Paul, Minnesota is a newly established business and cultural district. It is known as a destination for Asian cultures, authentic food and shopping. As an initiative of Asian Economic Development Association, Little Mekong mission is to develop the area at University Avenue and Western as an attractive destination for visitors and residents; to support and promote businesses during light rail construction; to share cultural traditions and activities; and to create a living, breathing, colorful district for all to enjoy. Little Mekong includes hundreds of businesses with different services such as restaurants, financial services, health services, etc. Despite different types of services, Little Mekong's businesses share many things in common as most of them are family owned businesses. They are all small businesses run by family members, who mainly are immigrants from Southeast Asian countries. Businesses for them are a way to support families and the future of the next generation. Also, with a wide variety of ethnicities and different languages spoken, the outreach activities and getting update information about the light rail construction encounter many difficulties. The research takes two businesses, Mai village and M.A.I Spine, as examples to conduct face to face interview with the owners about financial, human and social impacts of the CCLRT on the owners and their businesses. By using story telling style, the research focus on portraying the images of not only these two businesses but also the images of the owners as immigrants and how they have overcome many difficulties in order to start and maintain the businesses. At the same time, the researches emphasizes the other aspects of CCLRT's impacts that might be underestimate such as human and social impact on business owners and the community. Mai Village and M.A.I Spine are chosen for this research because of the similarity and uniqueness in the stories of immigrants as well as the difficulties that the owners suffer from the light rail construction. Mai village is one of the biggest and most famous restaurants in the neighborhood. Having been around for more than 20 years, Mai village has never experienced any severe difficulties as the construction brings to the restaurant. M.A.I Spine is one of the rare health services in chiropractic with expensive equipment such as MRI machine, which experiences a lot of impacts coming from the light rail construction. Both these two businesses have played an important role in shaping the neighborhood and supporting the community. Due to the construction impacts, Mai village is now facing their foreclosure and M.A.I Spine has thought about moving the location. Besides the loss of revenue, the owners and employees also experience health impact. With the businesses going down, it's also difficulty for businesses to give back and support the community. The stories of Mai village and M.A.I Spine are not individual but many other small businesses along University Ave are experiencing similar impacts from the CCLRT project.Prepared for the Asian Economic Development Association with funding from a Communiversity Personnel Grant from the Center for Urban and Regional Affairs (CURA), University of Minnesota.

Second Language Teachers’ Perceptions of Their Pedagogical Practices, Collaborations, and Relationships with Other Teachers through Professional Development

This paper reports on the relationship between language teacher practices and their collaborations with other teachers through professional development. The paper argues that there is a link between the disposition to use evidence-based practices in language teaching, and ongoing reinforcement of such practices through dialogic exchange in professional practice sessions. Furthermore, the paper understands the learning and development of such disposition as a career-long endeavour, first encountered in quality teacher education programs and then continued by committing to ongoing professional development. Survey data were collected from a group of language teachers from various second languages in primary and secondary schools in [state removed], Australia after they had participated in a workshop on language teaching methodology. The teachers reported extensive use of evidence-based language learning strategies in their classrooms. The paper argues that this disposition is grounded in the ongoing commitment of these teachers to stay in dialogic exchange with colleagues during professional development

A 2-pyridone-amide inhibitor targets the glucose metabolism pathway of Chlamydia trachomatis.

UnlabelledIn a screen for compounds that inhibit infectivity of the obligate intracellular pathogen Chlamydia trachomatis, we identified the 2-pyridone amide KSK120. A fluorescent KSK120 analogue was synthesized and observed to be associated with the C. trachomatis surface, suggesting that its target is bacterial. We isolated KSK120-resistant strains and determined that several resistance mutations are in genes that affect the uptake and use of glucose-6-phosphate (G-6P). Consistent with an effect on G-6P metabolism, treatment with KSK120 blocked glycogen accumulation. Interestingly, KSK120 did not affect Escherichia coli or the host cell. Thus, 2-pyridone amides may represent a class of drugs that can specifically inhibit C. trachomatis infection.ImportanceChlamydia trachomatis is a bacterial pathogen of humans that causes a common sexually transmitted disease as well as eye infections. It grows only inside cells of its host organism, within a parasitophorous vacuole termed the inclusion. Little is known, however, about what bacterial components and processes are important for C. trachomatis cellular infectivity. Here, by using a visual screen for compounds that affect bacterial distribution within the chlamydial inclusion, we identified the inhibitor KSK120. As hypothesized, the altered bacterial distribution induced by KSK120 correlated with a block in C. trachomatis infectivity. Our data suggest that the compound targets the glucose-6-phosphate (G-6P) metabolism pathway of C. trachomatis, supporting previous indications that G-6P metabolism is critical for C. trachomatis infectivity. Thus, KSK120 may be a useful tool to study chlamydial glucose metabolism and has the potential to be used in the treatment of C. trachomatis infections

К вопросу о значимости биомедицинской этики

БИОЭТИКАЗДРАВООХРАНЕНИЕ РЕСПУБЛИКИ БЕЛАРУС

Intraspecific varibility of corynespora cassiicola inferred from single nucleotide polymorphisms in ITS region of ribosomal DNA

Two single nucleotide polymorphisms (SNPs) were detected in the internal transcribed spacer region of the nuclear ribosomal DNA (rDNA-ITS) of 21 Corynespora cassiicola isolates obtained from a number of Hevea clones grown in rubber plantations in Malaysia. The two SNPs correlated with the physiological races of the isolates. Database searches yielded another 28 C. cassiicola isolates from diverse hosts and geographical regions. With this inclusion, a total of seven SNPs and two indels in the rDNA-ITS region were detected from all 49 C. cassiicola isolates. The knowledge of intraspecific variability (SNPs and indels) could prove useful in the delineation of physiological races or pathotypes of this fungus