Femtosecond Laser Patterned Templates and Imprinted Polymer Structures

Femtosecond laser machining is a direct-write lithography technique by which user-defined patterns are efficiently and rapidly generated at the surface or within the bulk of transparent materials. When femtosecond laser machining is performed with tightly focused amplified pulses in single-pulse mode, transparent substrates like fused silica can be surface patterned with high aspect ratio (\u3e10:1) and deep (\u3e10 μm) nanoholes. The main objective behind this dissertation is to develop single-pulse amplified femtosecond laser machining into a novel technique for the production of fused silica templates with user-defined patterns made of high aspect ratio nanoholes. The size of the nanoholes, both lateral and vertical, is controlled to a certain degree by controlling laser machining parameters or by chemical etching in a post-machining treatment. Fused silica templates produced by this new technique, both as-machined and chemically etched, are shown to be useful for imprinting polymer structures by a simple replication procedure using polymer thin films or solutions. In particular, a solution-based replication procedure, termed solution casting, is developed to imprint polymer structures from fused silica templates. Polymer structures in the form of nanowires, nanocones, and micropillars are successfully imprinted from various polymer types. Imprinted polymer structures are easily functionalized by subsequent surface treatment processes like cryogenic sputter coating and vapor deposition. A novel low-temperature chemical vapor deposition process is developed to coat polymer nanowires with silica to produce silica nanoneedles. Silica nanoneedles thus produced are shown to be useful as synthetic cell culture substrates to study the behavior of NIH 3T3 fibroblasts. In the final part of this dissertation, a report is given on more in-depth collaborative experiments to study the role of optical aberrations as part of the mechanism for producing high aspect ratio nanoholes by single-pulse amplified femtosecond laser machining. The results indicate that (i) precise optical alignment of the focusing lens is needed to avoid coma, which significantly deteriorates the ability to produce nanoholes, and (ii) 10-micron deep nanoholes can be produced by focusing a beam without spherical aberration but even deeper nanoholes are formed when the beam is focused with undercorrected spherical aberration

Centrifugal-Driven, Reduced-Dimension, Planar Chromatography and Nanoscribe Mesh Filters for Separations

The ability to separate chemicals is vitally useful to a wide variety of fields including chemistry, biology, pharmacology, and environmental analysis. Thin-layer chromatography is advantageous in the world of chemical separations as it is easy to use, can accommodate multiple samples at once, and has a wide range of applicability. However, this technique can be limited by band broadening, thus decreasing its efficiency. In an effort to increase efficiency particle sizes have been reduced, which in turn has decreased the mobile phase velocity. The used of micro- and nanopillar arrays systems mitigates this decrease due to the more ordered arrangement of the pillars, but efficiency is still limited by the mobile phase velocity. The work presented herein focuses on the fabrication and development of separation platforms that improve efficiency of pillar array chromatography systems by increasing mobile phase flow velocity through the use of centrifugal force.Likewise, the ability to separate particles on the micro- and nanoscale is important for many applications such as food processing, medical diagnostics, and cosmetics. There are a variety of techniques to create devices capable of sorting and separating micro- and nanoparticles. However, these devices are aimed at separating low volume high value samples. The second project described in the work herein proposed the use of micro 3D laser printing to create mesh filters in channels for the separation of nanoparticles suspended in solutions of low volume, as well as a system allowing the study of diffusion of particles through the mesh filters

Glassy Materials Based Microdevices

Microtechnology has changed our world since the last century, when silicon microelectronics revolutionized sensor, control and communication areas, with applications extending from domotics to automotive, and from security to biomedicine. The present century, however, is also seeing an accelerating pace of innovation in glassy materials; as an example, glass-ceramics, which successfully combine the properties of an amorphous matrix with those of micro- or nano-crystals, offer a very high flexibility of design to chemists, physicists and engineers, who can conceive and implement advanced microdevices. In a very similar way, the synthesis of glassy polymers in a very wide range of chemical structures offers unprecedented potential of applications. The contemporary availability of microfabrication technologies, such as direct laser writing or 3D printing, which add to the most common processes (deposition, lithography and etching), facilitates the development of novel or advanced microdevices based on glassy materials. Biochemical and biomedical sensors, especially with the lab-on-a-chip target, are one of the most evident proofs of the success of this material platform. Other applications have also emerged in environment, food, and chemical industries. The present Special Issue of Micromachines aims at reviewing the current state-of-the-art and presenting perspectives of further development. Contributions related to the technologies, glassy materials, design and fabrication processes, characterization, and, eventually, applications are welcome

Manufacturing of coir fibre-reinforced polymer composites by hot compression technique

This present chapter describes the manufacturing technique and properties of coir fibre-reinforced polypropylene composites manufactured using a hot press machine. The effects of basic chromium sulphate and sodium bicarbonate treatment on the physical and mechanical properties were also evaluated. Chemical treatment and fibre loading generally improved the mechanical properties. Five-hour basic chromium sulphate and sodium bicarbonate-treated coir-polypropylene had the best set of properties among all manufactured composites. Chemical treatment also improved water absorption characteristics. This proves that chemical treatment reduced the hydrophilicity of the coir fibre. Overall the hot compression technique was proved to be successful in manufacturing good quality coir reinforced polypropylene composites

Engineered nanomaterials: exposures, hazards, and risk prevention

Nanotechnology presents the possibility of revolutionizing many aspects of our lives. People in many settings (academic, small and large industrial, and the general public in industrialized nations) are either developing or using engineered nanomaterials (ENMs) or ENM-containing products. However, our understanding of the occupational, health and safety aspects of ENMs is still in its formative stage. A survey of the literature indicates the available information is incomplete, many of the early findings have not been independently verified, and some may have been over-interpreted. This review describes ENMs briefly, their application, the ENM workforce, the major routes of human exposure, some examples of uptake and adverse effects, what little has been reported on occupational exposure assessment, and approaches to minimize exposure and health hazards. These latter approaches include engineering controls such as fume hoods and personal protective equipment. Results showing the effectiveness - or lack thereof - of some of these controls are also included. This review is presented in the context of the Risk Assessment/Risk Management framework, as a paradigm to systematically work through issues regarding human health hazards of ENMs. Examples are discussed of current knowledge of nanoscale materials for each component of the Risk Assessment/Risk Management framework. Given the notable lack of information, current recommendations to minimize exposure and hazards are largely based on common sense, knowledge by analogy to ultrafine material toxicity, and general health and safety recommendations. This review may serve as an overview for health and safety personnel, management, and ENM workers to establish and maintain a safe work environment. Small start-up companies and research institutions with limited personnel or expertise in nanotechnology health and safety issues may find this review particularly useful

SPATIAL TRANSFORMATION PATTERN DUE TO COMMERCIAL ACTIVITY IN KAMPONG HOUSE

ABSTRACT Kampung houses are houses in kampung area of the city. Kampung House oftenly transformed into others use as urban dynamics. One of the transfomation is related to the commercial activities addition by the house owner. It make house with full private space become into mixused house with more public spaces or completely changed into full public commercial building. This study investigate the spatial transformation pattern of the kampung houses due to their commercial activities addition. Site observations, interviews and questionnaires were performed to study the spatial transformation. This study found that in kampung houses, the spatial transformation pattern was depend on type of commercial activities and owner perceptions, and there are several steps of the spatial transformation related the commercial activity addition. Keywords: spatial transformation pattern; commercial activity; owner perception, kampung house; adaptabilit

Environmental, Safety, and Health Considerations: Composite Materials in the Aerospace Industry

The Aerospace Industries Association, Suppliers of Advanced Composite Materials Association, and the National Aeronautics and Space Administration co-sponsored a conference on 'Environmental, Safety, and Health Considerations--Composite Materials in the Aerospace Industry.' The conference was held in Mesa, Arizona, on October 20-21, 1994. Seventeen papers were presented in four sessions including general information, safety, waste, and emissions from composites. Topics range from product stewardship, best work practice, biotransformation of uncured composite materials, to hazardous waste determination and offgassing of composite materials

Laboratory technology research - abstracts of FY 1997 projects

The Laboratory Technology Research (LTR) program supports high-risk, multidisciplinary research partnerships to investigate challenging scientific problems whose solutions have promising commercial potential. These partnerships capitalize on two great strengths of this country: the world-class basic research capability of the DOE Energy Research (ER) multi-program national laboratories and the unparalleled entrepreneurial spirit of American industry. A distinguishing feature of the ER multi-program national laboratories is their ability to integrate broad areas of science and engineering in support of national research and development goals. The LTR program leverages this strength for the Nation`s benefit by fostering partnerships with US industry. The partners jointly bring technology research to a point where industry or the Department`s technology development programs can pursue final development and commercialization. Projects supported by the LTR program are conducted by the five ER multi-program laboratories. These projects explore the applications of basic research advances relevant to DOE`s mission over a full range of scientific disciplines. The program presently emphasizes three critical areas of mission-related research: advanced materials; intelligent processing/manufacturing research; and sustainable environments