NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract BOOTSTRAPPING NANOSCIENCE AND ENGINEERING EDUCATION AT NC A&T STATE UNIVERSITY D. Pai, J. Sankar, C. Waters, D. Kumar and K. Roberts Center for Advanced Materials and Smart Structures Department of Mechanical and Chemical Engineering North Carolina A&T State University 1601 E Market Street, Greensboro, NC 27411 D. Bartz Center for Educational Research and Evaluation 210 Curry Bldg University of North Carolina – Greensboro Greensboro, NC 27402 M. Atwater, P. Ferreira Center for Nanoscale Chemical-Electrical-Mechanical Manufacturing Systems Department of Mechanical Engineering University of Illinois Urbana, IL 61801 Abstract Nanoscience and engineering principles are being incorporated into the existing curriculum and into new courses at North Carolina A&T State University (A&T). This is been done in an interdisciplinary manner, in several departments across two colleges on this campus. This bootstrapping effort has been invigorated by a recently initiated research and educational partnership with the University of Illinois – Urbana-Champaign (UIUC) in an NSF Nanoscale Science and Engineering Center (NSEC) entitled “Nanoscale-Chemical-Electrical-Mechanical Manufacturing Systems.” The education and outreach component of this work require the incorporation of nanoscience fundamentals and research outcomes into undergraduate and graduate curricula, as well as exposure of K-12 students and teachers to the opportunities and challenges in this nascent field. Educational modules introducing concepts of nanotechnology and nanomaterials have been developed by school teachers attending NSEC summer teacher workshops where they were exposed to cutting-edge research and facilities. These modules have been deployed at summer enrichment camps at A&T. Program evaluation is being done by collaborators from the University of North Carolina – Greensboro (UNCG) and UIUC’s College of Education. The paper discusses A&T’s coverage of nanoscience and engineering in multiple courses and our experiences with these modules as well as work towards integrating nanotechnology concepts into existing courses at A&T as we enter this exciting 21st century research arena. Introduction Nanoscience is the study of matter of the size scale of approximately one nanometer (1x10-9 m) to several hundred nm. Nanoengineering and technology1 enable the manipulation of molecules and atoms to produce nanoscale materials with novel properties due to their very small size. The potential benefits of nanoscience and engineering are extremely broad-based, spanning areas as Proceedings of the 2005 American Society for Engineering Education Annual Conference & Exposition Copyright © 2005, American Society for Engineering Education

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Session 3464 Materials Engineering Education for the New Millennium Devdas M. Pai & Jagannathan Sankar North Carolina A&T State University Abstract Advances in engineering design have tested the limits of performance of traditional materials. Developments in design can only be implemented suitable high performance materials are developed in lock step. Engineering students of all disciples must be provided a sound training in materials engineering beyond the scope of traditional materials. A new research center on campus, devoted to advanced materials and smart structures, has enabled instructors to utilize state- of-the-art research facilities, tools and personnel to enrich the classroom learning experience. The authors describe how their department’s undergraduate mechanical engineering curriculum is gradually being shaped to provide students with the necessary tools and information to understand, deploy and develop the materials of the new millennium. Introduction “Advanced materials are the building blocks of technology”1. Engineers of the next millennium, need to be aware that advances in design are starting to be limited by the performance of traditional materials. The development of advanced materials has been the enabler of never-before imagined performance. Electronic semiconductor-based circuits have been made much faster by gallium arsenide; fiber optics have made international communications cheaper and faster, and the development of heat-shielding ceramic tiles2 have enabled the Space Shuttle to safely re-enter earth’s atmospheres braving surface temperatures exceeding 1600 °C - far beyond the scope of any metal used in airframes. Materials science has justly earned its position as an important cross-disciplinary cornerstone of the engineering curriculum.

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Main Menu Session 1464 Materials Characterization by Digital Microscopy G. J. Filatovs, S. N. Yarmolenko, D. M. Pai and J. Sankar Department of Mechanical Engineering and NSF Center for Advanced Materials and Smart Structures, NC A&T State University, Greensboro, NC 27411 Abstract Materials characterization and analysis is the central theme of materials science. While computer- based methods greatly extend the scope of characterization techniques, these methods are associated with their own set of implementation issues in terms of image processing, statistical, and mathematical problems. Classical metallography does not prepare students for these challenges. We have developed a graduate course on microstructural characterization, analysis, and modeling that is based on concepts of stochastic microstructures and uses model systems based on spatial geometry concepts of point processes, packings, and tessellations. Using discrete constituents such as discs, we develop the fundamental ideas of spatial geometry and image algebra more transparently to aid student comprehension. Once these principles are covered, we extend them to more complex structures such as multiphase materials. Introduction This paper discusses our experiences with a 3-semester-hour (2 lecture and 2 laboratory hours) course taught to graduate students in the Department of Mechanical Engineering at NC A&T State University; these students were from different research groups and facilities but worked within the framework of the NSF Center for Advanced Materials and Smart Structures (CAMSS) for this special topic course. Their thesis topics ranged from computational mechanics to traditional materials science topics (semiconduction, nanomaterials), the materials primarily being composites (carbon/polymer, carbon/carbon, ceramic/ceramic) or monolithic ceramics. The topic of the course was the evolved equivalent of “Quantitative Metallography”, the examination of microstructures in the optical and scanning microscope ranges. Because of the students varied background paths to the program, it was necessary to supply collateral support in statistics, spatial geometry, computer topics, and the property-structure link. The presentation of sufficient amounts of these topics in an integrated manner provided the major challenge for the course. Course Scope Like other areas, materials science is evolving a new relationship to the computer, which is bringing a strong link with mathematics and statistics. This is raising the expectations of microstructural analysis; however, an interpretative and analytic strategy is still needed and the translation of microstructure into the framework of computation or model is rarely trivial. This has resulted in an increased scope for the typical microstructures course, transforming it from metallurgy to materials. Proceedings of the 2002 American Society for Engineering Education Annual Conference & Exposition Copyright © 2002, American Society for Engineering Education Main Menu

A piezoelectric material is basically a ceramic that outputs a voltage upon being mechanically strained.Sensors made of this material are sensitive enough to generate signals when subjected to low-amplitude mechanical waves such as sound waves traveling through solids.This makes them candidate materials for all kinds of exciting applications.For example, sensors mounted on a wing surface could detect ice formation on the wing using surface active waves.Since the velocity of sound in a given medium is a function of temperature, such sensors are also being used to actually measure temperature.It is important for students to be aware of this new generation of materials and to be familiar with the use of these materials for measuring fundamental quantities such as the velocity of sound.This experiment has been designed for use in an introductory mechanical or materials engineering instrumentation lab.Initial setup (after procuring all the materials) should take the lab instructor about 2 hours.A single measurement can be initiated and saved to disk in less than 3 minutes, allowing for all the students in a typical lab section to take their own data rather than share a single set of data for the entire class.This experiment is offered to a sophomore-level laboratory class in mechanical engineering that focuses on measurements, instrumentation and manufacturing and addresses the first two topics in that course.

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Session 1463 Computer Aided Materials Selection for Design and Manufacturing D. M. Pai, B. Kailasshankar, C. Adams and G. J. Filatovs Center for Advanced Materials and Smart Structures Department of Mechanical Engineering North Carolina A&T State University Greensboro, NC 27411 Abstract Machine design as taught in most machine design courses tends to focus mainly on considerations of geometry and stress analysis, with the selection of material and manufacturing processes and the specification of manufacturing tolerances becoming almost an afterthought. Although most engineering students are taught materials science as a fundamental science course, the curriculum downstream does not foster the incorporation of these principles into the systematic selection of the most appropriate material for a certain shape and function, or the criterion-based selection of the optimal manufacturing process. Tighter integration between the introductory materials courses and the downstream design and manufacturing courses is just part of the solution. With the advances in materials and manufacturing technology, a plethora of materials and processes has evolved. Undergraduate courses in design and manufacturing cannot provide detailed coverage of all materials and processes, and thus one has to harness the knowledge archiving and retrieval capabilities possible with today’s information technology. The authors describe their experiences with a popular materials and process selection program (Cambridge Engineering Selector) that has been deployed in a junior level manufacturing processes class as well as a senior/graduate level aluminum design class. Students experience different aspects of the software, with the usage of its vast capabilities getting more sophisticated as they progress along the curriculum. Background The process of design necessitates a good understanding of the properties of materials as well as the manufacturing processes necessary to create a product out of these materials. Fundamentals of material behavior and of manufacturing processes are, in most engineering curricula, typically imparted in engineering science type courses early in the curriculum. The actual usage of this information in the design process is left to the capstone machine design projects and engineering design courses. There is a disconnect between the learning of the early years and the real-world product design work that follows. This is natural, because fundamental classes talk in generalities – materials, for example, are classified broadly as metals, ceramics, polymers and composites and their general structure, mechanical and physical properties are discussed. Likewise, manufacturing processes are broadly classified into forming, solidification, removal and joining. It is always somewhat of a shock for students to learn that the number of real-world materials available1 to them for engineering design range between 40,000 – 80,000 instead of the idealized four or five categories taught in class. Similarly, there are thousands of Proceedings of the 2003 American Society for Engineering Education Annual Conference & Exposition Copyright © 2003, American Society for Engineering Education

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Session 3263 Using Design Contests to Enhance Manufacturing Education Devdas M. Pai, Juri Filatovs & Richard Layton North Carolina A&T State University Abstract Synthesis and design of new materials, devices and processes is typically considered the capstone of the engineering education experience. Design contests of one sort or another proliferate engineering societies of all disciplines. Less emphasis is placed on manufacturing - the basic enabling technology required to reduce art to part. For curricula that allocate insufficient curricular credits for courses explicitly labeled as manufacturing; invention, as a wag has remarked, becomes the necessity of mother. In this paper, the authors describe their experiences with the use of design contests as a tool for manufacturing engineering education. Background Since engineers are valued for their creative and problem-solving skills, it is but natural that project work constitutes a large part of their professional training. The undergraduate mechanical engineering curriculum at NC A&T State University is no exception to this norm. The mechanical systems stem of this curriculum begins with a manufacturing and instrumentation lab course, followed by courses in machine design, manufacturing processes and industrial automation. Most of these courses entail design projects. Having to work on many diverse short-term projects hinders the student’s development of depth in understanding. We have been experimenting with the use of selected aspects of a national professional society sponsored design contest problem to emphasize important principles in design and manufacturing across several courses. ASME National Student Design Contest

Topic/Session: -Issues in recruiting, building and enabling diversity in engineering graduateeducation A MODEL FOR INCLUSIVE EXCELLENCE IN GRADUATE ENGINEERING EDUCATIONAbstractBased on pressing national need for workforce diversity and current barriers to under-representedminority students’ (URM) participation in academia, a model for inclusive excellence in engineeringeducation is proposed as a comprehensive data driven plan designed for effective tool for capacity-building. Production of increased number of women and URM graduates in STEM fields is achievedthrough broad-based outreach programs targeted at K-12 school students, community college students,Historical Colleges and Universities, teachers, counselors, parents and administrators. This paper attemptsto frame university’s progress of promoting diversity and inclusive excellence through five broaddimensions or goals across its academic departments and research centers:1. Establish a Multi-Campus Pipeline Framework for a Pre-College to PhD (Identification/ Recruitment) in STEM fields: Institutionally, this means developing an effective model for creating a multi-campus bridge program and academic culture that support the identification and preparation of eligible URM undergraduates for the PhD-track in STEM fields. The academic departments and associated partners are recognizing their roles in creating opportunities for inclusive access for STEM education through pre-college education and outreach programs embedded in faculty research.2. Build a Graduate Student-Centered Community (Mentoring/Retention). Institutionally, this means developing a structure for effective community engagement and mentoring partnership with all stakeholders (graduate students, post-docs, faculty, staff, and administrators) for production of increased number of URM in STEM PhD and postdoctoral programs. University’s academic units and research centers are recognizing their roles in capacity building for STEM workforce pipeline by broadly engaging graduate and undergraduate women and underrepresented minority students in center activities and building strategic relationships for Integrating Research, Education, Outreach and Diversity across partner institutions.3. Create Professional Development Opportunities that Build Community Among Graduate Students, Postdoctoral Fellows, and Faculty Members for school of engineering, it means recognizing its role in capacity building for STEM workforce and engaging women and underrepresented minority faculty in STEM activities.4. Foster an Inclusive academic climate that pays attention to the cultural differences learners bring to the educational experience, a climate that welcomes and engages all of its diversity in the service of students and organizational learning.5. Develop and implement a comprehensive Diversity and Equity Scorecard (DES). Strategically, DES is a comprehensive tool for assessing school-wide progress and effectiveness in meeting its diversity and equity goals of increased access, excellence, retention, scholarship, positive environmental climate, and success of all students and faculty, especially women and underrepresented students and faculty. DES provides the assessment data and outcome-based strategy for improving school effectiveness in closing equity, inclusion or educational outcomes gaps (access, enrollments, retention, excellence, graduation, global preparedness) for all students, and equity gaps (recruitment, retention, scholarship, excellence) for all faculty and staff in a positive environmental climate.Some key performance indicators include high production of women PhDs in engineering. The AmericanSociety for Engineering Education ranked the school as second in North America for percentage ofdoctoral degrees awarded to women in 2009.

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Session 1464 Show Me: Making An Impact With Sandwiches Devdas Pai, William Craft, Ajit Kelkar, Sunil Shenoy, Ronald Bolick North Carolina A&T State University Abstract Research in the transportation industry is largely driven by the need to cut costs and weight and to develop structures with better impact absorption capabilities. Metal and/or composite honeycomb core materials sandwiched between metal or composite end plates have been used in high performance, high-stake aerospace structural members, and they hold a promise that sandwich structures can be made which are light, cheap, and so energy absorbent that they will revolutionize common ground transportation systems. NC A&T State University has a number of grants involving research into impact damage including impact behavior of sandwich structures. The authors feel that this research is sufficiently mature and important so that impact experiments should be added to our laboratory sequence within the department. Research investigations of these materials in our labs involve static and dynamic testing including shear testing or impact testing, and it is relatively simple to include the important attributes of impact testing as a laboratory experiment. Motivating factors for us in developing new impact experiments include: • providing our students with additional information on how to design (impact) experiments. • enhancing our current educational content on data acquisition systems for dynamic events, and • educating our graduates in an important technology for the 21st century. We feel that knowledge of impact phenomena and testing is an important modern design methodology.

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Engineer Starters Program ABSTRACT At North Carolina Agricultural and Technical State University, the Engineer Starters Program (ESP) serves as an avenue to target specifically those underrepresented in the Science, Mathematics, Engineering and Technology fields and provide them with tools necessary for success in today’s highly technical world. Designed for rising seventh through rising twelfth graders, it is a two-week program, meeting Monday through Friday. (ESP Jr. is an abbreviated version for rising fifth and sixth graders.) The program is a commuter program therefore the students are chosen from schools within a 50 mile radius. Applications are given to the area school counselors and the interested students complete and return an application, hand written essay along with an official transcript (or original grade report) and two letters of recommendation from a teacher and/or school counselor. The program consists of morning sessions which expand their math and science skills in addition to career exploration. The afternoons expose the students to University research in a manner they can understand. Participants may encounter Computer Applications; Computer Drafting; Electrical Circuits; Nanotechnology and in each area they are coached in Project Presentations. Each area is presented in the form of modules which attempt to relate back to learning outcomes in their public schools. Rounding out the program, other subjects covered include Human Factors/Ergonomics Engineering, Lower Level Supply Chain Management and Web Page Design along with Energy Awareness and Alternatives; Hydrogen Fuel Cells and Photovoltaics. The incorporation of such a variety of subjects stimulates the youths’ interests in engineering, in general, and Industrial, Architectural and Mechanical Engineering, in particular. Funding for this program is varied according to the research center involved and comes from varied sources. STATEMENT OF PURPOSE AND PLAN This nation has long recognized the absence of diversity within science and math based professions. North Carolina A & T State University (NCAT) has pioneered the effort to encourage women and minorities to consider careers in the varied fields of engineering. NCAT is one of the very few Historically Black Colleges or Universities (HBCUs) that maintains a College of Engineering. Thus NCAT has consistently been near the top, if not at the top, of the annual lists of universities producing engineering graduates. The college offers majors in nine

NOTE: The first page of text has been automatically extracted and included below in lieu of an abstract Main Menu Session 2425 Integration of Materials Science into an Industrially-Sponsored Engineering Design Course D. M. Pai, G. J. Filatovs and J. Sankar NSF Center for Advanced Materials and Smart Structures Department of Mechanical Engineering NC A&T State University, Greensboro, NC 27411 Abstract An industrially-sponsored aluminum product design elective course offered over the past six years has dealt with a range of design projects principally chosen from the transportation and structural field. Engineers from industry present the problem and a panel of engineers reviews the end-of- semester oral and written reports. As with many mechanical engineering component design courses, this course tended to primarily emphasize the stress analysis portion of the design process. However, feedback from the sponsors over the years has made it clear that material selection, behavior and a good understanding of manufacturing processes and economics deserves enhanced coverage in such projects. In courses with limited materials science content, it is impossible to cover all the detail and background information really needed. Because the structure-property correlation in materials is a centerpiece in materials science, the authors have utilized it as a bridge between courses that have borderline materials content and truly materials- centric courses. An instantiation of this bridging effort is presented in this paper in the description of a shared project between a graduate-level materials characterization course and the aluminum product design course referred to above. Test specimens from the aluminum course were analyzed by the characterization class and the interaction provided the aluminum class students with specific structural detail and a basis for the micro-level mechanisms which originate the continuum properties required for mechanical design. Introduction Design, be it design of structures, manufacturing processes, or software, is becoming a function that involves more than technology/engineering [1]. Designers who decide upon and outline the main features of products and processes need to extend their talents/skills beyond the technology aspects of a business enterprise. The education and training of ‘designers’ must prepare them for commercial as well as technical aspects of the design processes of the 21st century. The 21st century design engineer will not only account for the performance and manufacturing aspects of the product, but also attempt to optimize the product to accommodate operational and commercial aspects of the business enterprise such as: capacity/profitability tradeoffs in using existing facilities/processes, the methods and mechanics of product delivery/distribution, customer specific attribute preferences, etc. The authors and their collaborators at the industrial sponsor (Alcoa Technical Center) have been working to shape the education process for engineering design students by collaborating in the offering of a course on aluminum design. This is in concert with the mechanical engineering Proceedings of the 2002 American Society for Engineering Education Annual Conference & Exposition Copyright © 2002, American Society for Engineering Education Main Menu

The ability to produce composite nanofibers of inorganic particles and synthetic polymers represents a significant advancement in the development of composite materials for potential biomedical applications. In this study, composite nanofibers of magnesium oxide (MgO), poly(epsilon-caprolactone) (PCL) and chitosan (CS) with diameters in the range of 0.7-1.3 mu m were fabricated by electrospinning their blend solutions in trifluroethanol and water. To support the potential use of these nanofibrous membranes for biomedical applications their physicochemical properties such as morphology, mechanical strength, and integrity in aqueous medium, were studied. Cellular compatibility was determined using cell viability assays and microscopy imaging, with the results showing that the nanofibrous membranes support 3T3 cell viability and attachments. The new composite nanofibrous membranes developed in this study have the ability to mimic the physical structure and function of tissue extracellular matrix (ECM) and thus have potential for many tissue engineering applications.

This study focused on understanding the interactions between alloying elements in a magnesium (Mg) matrix and the effect of the alloying elements on corrosion behavior of Mg-alloys. The development of atomic force microscope (AFM) techniques has enabled the evaluation of physical and chemical properties of surfaces at the sub-micron level. Scanning Kelvin probe force microscopy (SKPFM) is particularly useful for studying localized corrosion phenomena of alloys. SKPFM generates a map of the potential distribution across a sample with a resolution of probe tip radius, nowadays ranging from 5 to 30 nm. Furthermore, the open circuit potential of various pure metals in solution is linearly related to the Volta potential value measured in air immediately after exposure to corrosive media. SKPFM is a useful tool to practically assess the nobility of a surface. This technique has been applied to the heterogeneous microstructure of Mg-Zn-Ca-RE (RE = Zr, Nd, Ga) alloys and provided clear evidence regarding the shape, position, compositional inhomogeneities and local practical nobility of intermetallic particles. Correlation between the measured potential distribution and the reactivity of these particles has been shown. Atomic force lithography (AFL, scratching with the hard tip) is a controlled method for local disruption of the protective oxide film that naturally formed on an Mg-surface in air. Combining SKPFM and AFL, the stability of the passive film and the tendency for stabilization of localized corrosion can be monitored. In addition, the lateral imaging capabilities of the AFM provide an approach to study the role of different microstructural features such as grain boundaries and impurities in the process of inducing localized corrosion.

Formation of long-period stacking ordered (LPSO) phases can significantly improve mechanical and corrosion properties of Mg-alloys. Typically LPSO phases can be formed by quick solidification of Mg-alloys having at least two alloying elements with atomic radii higher and lower than that of Mg. Stability of LPSO phases greatly depend on amounts and ratio of alloying elements. We report formation of thin film LPSO structures produced by co-sputtering of magnesium with zinc and gadolinium having less than 10% of alloying elements. This method allows controlling the ratio of the elements in composition, deposition temperature and orientation of thin films. Pure Mg, Zn and Gd films and their alloys deposited at temperatures below 200°C have HCP Mg-based crystallographic structure with exclusively basal orientation. LPSO phases and their stacking period were detected by observation of laminar structure patterns in low-angle x-ray reflectometry scans. The study of effects of elemental composition, deposition temperature and post-annealing of room temperature-deposited films on the formation of LPSO phase showed that the co-sputtering method can be very useful and efficient for the screening of new LPSO phases without the considerable expense preparation of bulk alloy preparation.

The micro-alloying effect, mechanical properties, and plastic deformation behavior of extruded Mg-Zr alloy were investigated and characterized as a function of Zr addition, grain size, and texture. The experimental methodology used in this study was design to exploit the hot-extrusion processing parameters (in the terms of extrusion ratios and temperature) and its effect on Mg extruded alloys microstructure, texture, and mechanical properties. Microstructural observations revealed significant grain refinement through a combination of Zr addition and hot-extrusion, producing fine equiaxed grain structure with grain sizes ranging between 1–5 μm. Texture analysis and partial compression testing results showed that the initial texture of the extruded alloy gradually evolved upon compressive loading along the c-axes inducing contraction twinning creating a strong basal texture along the extrusion direction. Full tensile and compression test at room temperature showed that the combination of hot-extrusion and Zr addition can further refine the grains of the Mg alloys microstructure and enhance the texture while simultaneously enhancing the mechanical properties.

Magnesium injection is a suitable approach for replenishment of its ions (Mg++) during neural or tissue injury and stroke to avoids risks associated with abnormally low level of Mg++ in blood. In this study, alginate encapsulated magnesium sulfate microbeads were fabricated by the electrospraying technique for Mg++ delivery. Microbeads were evaluated for particle size and surface morphology using inverted optical microscopy and scanning electron microscopy (SEM) respectively. Average particle size of 200–500 μm for hydrated and 50–200 μm for dry beads were observed. An in vitro release study of Mg++ was performed; revealing a cumulative release of ∼50% within first 24 h. This strategy can potentially be useful for the targeted local delivery of magnesium at required concentrations and subsequently enhance the therapeutic efficacy of magnesium in treating tissue injury or stroke.

Bone is a living tissue that constantly remodels and adapts to the stresses imposed upon it. Bone disorders are of growing concern as the median age of our population rises. Healing and recovery from fractures requires bone cells to have a 3-dimensional (3D) structural base, or scaffold, to grow out from. In addition to providing mechanical support, the scaffold, an extracellular matrix (ECM) assembly, enables the transport of nutrients and oxygen in and removal of waste materials from cells that are growing into new tissue. In this research, a 3D scaffold was synthesized with chitosan (CS), carboxymethyl chitosan (CMC), calcium phosphate monobasic and magnesium oxide (MgO). CS is a positiviely-charged natural bioactive polymer. It is combined with its negatively-charged derivative, CMC, to form a complex scaffold. Magnesium phosphate biocement (MgP), formed by reacting calcium phosphate monobasic and MgO, was incorporated into CMC solution before adding CS solution. Scaffolds were prepared by casting, freezing and lyophilization. The scaffolds were characterized in terms of pore microstructures, surface topography, water uptake and retention abilities, and crystal structure. The results show that the developed scaffolds exhibit highly interconnected pores and present the ideal pore size range (100–300 μm) to be morphometrically suitable for the proposed bone tissue engineering applications. These scaffolds not only mimic the nanostructured architecture and the chemical composition of natural bone tissue matrices but also serve as a source for soluble ions of magnesium (Mg++) and calcium (Ca++) that are favorable to osteoblast cells. The scaffolds thus provide a desirable microenvironment to facilitate biomineralization. These observations provide a new effective approach for preparing scaffold materials suitable for bone tissue engineering.

MgZnCa and MgZnCa-RE (Rare Earth) alloys were developed for biomedical applications. Small wires of the alloys were successfully fabricated from the small rods prepared by hot-extrusion followed by multiple cold-drawing passes with intermittent annealing. It was demonstrated that addition of small amounts of rare earth (RE) elements could effectively enhance the mechanical properties of the wires. The ductility or deformability under twisting test was greatly improved by post annealing at relatively high temperatures.

Bone has a remarkable ability to regenerate and heal itself when damaged. Most minor injuries heal naturally over time, but when the defects are larger, they require a substrate to support the cell growth and guide the repair process. Bone grafting is currently done by using either an autograft, where the substrate is harvested from a suitable donor site within the patient’s body; or an allograft, where the substrate is harvested from a cadaver. However, both techniques have significant drawbacks. In autografting, significant complications tend to arise from donor site morbidity. In allografting, the issues are the risk of disease transmission, and the logistical difficulties in the local or even global matching process for donor tissue. A third approach, employing tissue-engineered scaffold materials, provides superior performance by helping to restore bone tissue functions during regeneration and by subsequent resorption of the graft material as new bone tissue forms. These bioactive scaffolds are porous and made of natural materials that are capable of harboring growth factors, drugs, genes, or stem cells. The objectives of this research are to synthesize biofunctional composite scaffold materials, based on chitosan (CS) and magnesium (Mg), for use in bone regeneration and to measure their physiochemical properties. Scaffolds were fabricated from the aqueous dispersions of starting materials by subsequent freezing and phase separation by the lyophilization process. A CS solution was prepared by dissolving CS in 2 % (v/v) acetic acid solution, whereas carboxymethyl chitosan (CMC) was dissolved in deionized water. The concentrations of CS and CMC (in a constant 1:1 weight ratio) ranged between 2% and 5 %. Various dry weight percentages of Mg gluconate (MgG) were added to the scaffolds by dissolving the MgG solution in the CS/CMC. SEM imaging showed the scaffolds to possess uniform porosity with a pore size distribution range of 100–150 μm. Micro CT analysis showed that the pores were distributed throughout the scaffold’s entire volume and they were highly interconnected. Compressive strengths of up to 340 kPa and compressive moduli of up to 5 MPa were obtained for these fabricated scaffolds. When introduced into a cell culture medium, these scaffolds were found to remain intact, retaining their original three-dimensional frameworks and ordered porous structures maintaining sufficient mechanical strength. These observations provide a new effective approach for preparing scaffold materials suitable for bone tissue engineering.

In recent years, magnesium (Mg) and its alloy are being studied for their potential use in orthopedic implants with the novel ability to biodegrade after the implant serves its therapeutic function. Pure Mg, by itself, would not be suitable for use in a load-bearing implant application, due to its high corrosion rate and poor tribological properties. However, through proper alloying, this degradable metal is capable of achieving good mechanical properties reasonably similar to bone, a retarded rate of corrosion and enhanced biocompatibility. Previous studies have shown that alloying Mg with aluminum, lithium, rare earth (RE), zinc (Zn), and calcium (Ca) result in lower corrosion rates and enhanced mechanical properties. Despite the growing popularity of Mg and it alloys, there is relatively little information in the literature on their wear performance. In this paper, we report on an investigation of the directional tribological properties of Mg and Mg-Zn-Ca-RE alloy fabricated via two different manufacturing processing routes: as-cast and hot-extruded after casting, with extrusion ratios of 10 and 50. Pure Mg was cast 350°C. After casting, Mg-Zn-Ca-RE alloy was heat-treated at 510°C. Another Mg-Zn-Ca-RE alloy was hot-extruded at 400°C. Dry sliding wear tests were performed on as-cast and hot-extruded pure Mg and Mg-Zn-Ca-RE alloys using a reciprocating test configuration. Wear rate, coefficient of friction and wear coefficient were measured under applied loads ranging from 0.5–2.5N at sliding frequency of 0.2 Hz for 120 cycles, using microtribometery. Wear properties of the extruded specimen were measured in cross-section and longitudinal section. In the longitudinal section studies, wear properties were investigated along the extrusion direction and the transverse direction. Hardness properties were evaluated using microindentation. Cross-section and longitudinal section were indented with a Vickers indenter under applied load of 2.94 N. Alloying and extrusion enhanced the mechanical properties significantly, increased hardness by 80% and wear resistance by 50% compared to pure Mg. Despite the low hardness in both Mg and the Mg alloy cross-sections, the cross-sections for both displayed higher wear resistance compared to the longitudinal section. In the longitudinal section, wear resistance was higher along the transverse direction of the longitudinal section for both Mg and the Mg alloy. The wear coefficient was used to evaluate how the wear behavior of the material varied with respect to alloying, fabrication process, and direction of wear. The wear coefficient of pure Mg decreased as the extrusion ratio increased, thus, increasing the specific wear rate. The opposite behavior was found in the Mg alloy: as the wear coefficient increases, the specific wear rate decreases. The active wear mechanisms observed on the worn surface of Mg were fatigue, abrasive, adhesive and delamination wear. The same wear mechanisms were observed in the Mg alloy except for fatigue wear. Surface microstructure and topographical characterization were conducted using optical microscopy, scanning electron microscopy mechanical stylus profilometry, and optical profilometry.