Jarlen Don

Basal plane orientation of polyacrylonitrile fibers in a commercial polyacrylonitrile-pitch carbon-carbon composite

Abstract The basal plane orientation of polyacrylonitrile (PAN) fibers in a commercial three-dimensional high-temperature-treated PAN-pitch carbon-carbon composite has been studied by conventional transmission and high resolution electron microscopy techniques. Thin foils of the composite are prepared by an atom-thinning technique. A basal plane orientation, which differs from other reported type I PAN fibers, is reported. In transverse sections, a turbostatic structure is observed across the whole fiber thickness. In longitudinal sections, the degree of perfection for basal plane alignment to the fiber axis decreases from fiber surface to the core in a gradual fashion. The lack of a well-aligned thin skin or thick sheath structure agrees with Oberlins model but can be distinguished from the models of Bennett and Johnson and others.

A novel stone retrieval basket for more efficient lithotripsy procedures.

This paper presents the development of an improved stone retrieval device that uses a newly designed cage of Nitinol wires encompassing a mesh basket made of a material that is laser resistant. Current methods to extract large stones involve imaging, using a laser to fragment the stones and then using existing cage-like baskets to trap the fragments individually and extracting them one at a time. These procedures are tedious, and may result in leaving some fragments behind that can reform causing the need for another procedure. The device presented in this paper will have a mesh-like sack which will consist of a laser resistant material of polytetrafluoroethylene (PTFE) enclosed within a newly designed Nitinol cage. Two alternate designs are provided for the cage in this paper. The handle of the device is revised to allow for a 3 Fr (1 mm) opening such that a lasers fiber optic cable can enter the device. Using this device a laser can be used to fragment the stone, and all the fragments are retained in the basket in both the design options. The basket can then be retracted allowing for the retrieval of all the fragments in one shot. The stone retrieval basket presented in this paper will significantly improve the efficiency and effectiveness of lithotripsy procedures for removal of large kidney and biliary tract stones.

Defect characterization in commercial carbon- carbon composites

A relatively inexpensive and easy to operate custom built infrared thermography (IRT) system was developed and utilized for the detection and characterization of defects in Carbon-Carbon (C/C) composite aircraft brake disks. This method uses an active infrared thermography (IRT) approach, i.e. Flash Heating method, for a non-destructive evaluation (NDE) of C/C brake disk materials. The experimental results obtained from the developed system were then compared with commercial IRT turn-key system. In addition, Finite Element Analysis (FEA) was also carried out to determine the detectible defect depth and diameter of the defects in C/C composites to validate the experimental results. The experimental results were compared to the FEA results and it was found that they were in good agreement with one another.

Development of bamboo‐derived sorbents for mercury removal in gas phase

Activated carbon sorbents were synthesized from bamboo precursors by carbonization in an inert atmosphere followed by physiochemical activation with carbon dioxide and finally acidulation in hydrochloric acid. Bamboo strips with and without the epidermal tissue (bark) were used. The morphology and specific surface area changes due to the treatment were analysed. The adsorption characteristics of these sorbents after each stage of treatment were also analysed and the data were correlated to the changes in the physical characteristics of the sorbents. Kinetic studies were conducted on these samples. The adsorption equilibrium and kinetics of elemental mercury adsorption on these carbons were evaluated at room temperature. Elemental mercury uptake at different sorbent loading and initial elemental mercury concentrations were examined. The adsorption rate constants and the mass transfer constants were estimated for the sorbents prepared under different conditions. Adsorption isotherms of the elemental mercury on these activated carbons were determined and correlated with Langmuir and Freundlich adsorption isotherm equations. It was found that the overall process was mass transfer controlled and that the adsorption equilibrium could be described by a linear isotherm for the concentrations used in this study.

Influence of Diamond-like Carbon Coatings on the Fatigue Behavior of Spinal Implant Rod

The purpose of this paper is to discuss the influence of Diamond–Like Carbon (DLC) coatings on the fatigue behavior of Spinal implant rod. DLC exists in seven different forms of amorphous carbon materials that display some of the unique properties of diamond. They are usually applied as coatings to other materials that could benefit from some of unique diamond properties. In this work, we compared bending fatigue behavior between Stainless Ti6Al4V and DLC Coating Spinal implant rod. The positive effect has been observed by fatigue tests carried out at ASTM Standard D790. Fatigue life and endurance limit of spinal implant rod have been remarkably increased by means of thin DLC coatings. The improvement of fatigue characteristics of spinal implant rod by DLC coatings has been ascribed to the sealing of external defects which retards crack initiation.

Development of a Control System for Automating of Spiral Concentrators in Coal Preparation Plants

Spiral concentrators have been widely used in coal preparation plants in Illinois and elsewhere to clean 1 mm ×150 μm particle size coal fraction. The major factors which have made spiral concentrator so popular include its low capital and operating cost, no chemical reagent or dense medium requirement, and the ease of operation/maintenance. Spirals are capable of providing excellent clean coal recovery although at a relatively high ash content. Like any other water-only separation process, spirals are also susceptible to continuously fluctuating feed quality and solids content in the feed slurry, which are quite common in a plant. The main objective of the project is to develop an inexpensive control system for spiral to automatically adjust the splitter position with fluctuating feed characteristics to maintain the desired effective separation specific gravity (density cut-point).

Novel Materials for the Direct Removal of Water and Ions from the Body for Patients with Dialysis Needs

This paper describes a novel material for the direct removal of water and ions from the body of patients with End Stage Renal Disease (ESRD). The work is part of a larger project that is envisioned to be a new type of dialysis process that could replace or enhance existing dialysis methods. The main idea is to implant a unit either and/or outside the body of the patients with renal failure so that they do not have to go through the painstaking and exhausting hemodialysis or peritoneal dialysis processes existing today. The proposed work in its final embodiment will eliminate such processes and allow the patients to lead a more normal life than is possible with current state-of-the-art processes and equipment. This paper provides preliminary results to show that a sol gel based material has been formulated that can absorb 30% water, 30% sodium ions and almost 50% potassium ions in a laboratory setting from a mixture that simulates the amounts produced by the human body with ESRD.

A Fuzzy Logic Based Decision Making System for Fusing Measurements From an E-Puffer and E-Sniffer Sensing Systems for Detecting Explosives

This is primarily a concept paper and describes a decision making system that fuses the output from cold plasma based E-Puffer and E-Sniffer sensing systems to reliably detect explosive traces. This paper describes research and development of a novel non-contact method to detect explosive bearing personnel, baggage and vehicles that is based on the integration of a multitude of key technologies, primarily cold/atmospheric plasma and pattern recognition/decision making capabilities. This work will ultimately lead to a viable system that can be installed in doorways of buildings, garages, baggage carousals, etc. that will trigger a positive response when detecting explosive traces on personnel, bags or vehicles going thru a doorway. This paper describes the basic product concept and provides preliminary results of the fusion process from a simulated data set of output measurements from the two orthogonal measurement systems.Copyright

QNDE of a 3-D Carbon-Carbon Composite Using Photoacoustic Microscopy

A composite is composed of several distinct material components, one of which is contiguous and forms a matrix. The overall properties of the composite material are some average of the properties of its components. The fiber reinforced composites, like the carbon-carbon composites, are heterogenous materials consisting of reinforcement fibers embedded in a matrix. In most cases, the matrix may be considered homogenous and isotropic, but not the fiber reinforcement, which are highly anisotropic fibers. These fibers are grouped into yarns and woven in specific directions. The thermal properties of the matrix and the fibers are usually different. Thermally, the fibers are more conductive than the matrix and play a dominant role in the heat transfer through the composite, especially when the heat flux is parallel to one of the fiber reinforcement directions. The complex nature and strong thermal anisotropy of the fiber reinforcement makes characterization and modeling of 3-D carbon-carbon composites very difficult. Recently, [1,2,3,4,5] using the flash method for measuring thermal diffusivity, the in-situ thermal properties of the constituents of composite materials were determined.