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At least 19 recordsLinked to original sources
PubMed2001

Vibratory sample magnetometry of middle ear prostheses and manufacturing materials.

OBJECTIVE: To assess the magnetic properties of stapes prostheses and manufacturing materials using a vibratory sample magnetometer (VSM). DATA SOURCES: VSM was performed on 16 samples, including ferromagnetic 420F stainless steel, with an LDJ Model 9600 VSM in accordance with American Society for Testing and Materials standard A894. RESULTS: A VSM measures the magnetic dipole moment of a sample in a magnetic field. The magnetic field is swept over a range of magnetic fields, and the magnetic dipole moment is plotted as a function of field. The prostheses made of 316L stainless steel previously found to be ferromagnetic had the highest specific magnetic moments. The specific magnetic moments ranged from 0.023 electromagnetic units (emu)/g to 156 emu/g. The samples made with 316L stainless steel, which is used in otologic implants, were significantly less magnetic than was the 420F stainless steel. CONCLUSION: VSM demonstrates that prostheses made with 316L stainless steel are relatively nonferromagnetic compared with 420F stainless steel. However, none of the implants are nonmagnetic. The torque and linear force on the prosthesis is a concern. The safety of performing MRI on patients with these implants needs to be further assessed.

Electromagnetic Fields↗
PubMedDate not supplied

Quantification of allergenic urushiols in extracts of Ginkgo biloba leaves, in simple one-step extracts and refined manufactured material (EGb 761).

Extracts of leaves of Ginkgo biloba (family Ginkgoaceae), widely used in the treatment of peripheral and cerebral circulatory disorders as well as for dementia of different aetiology, contain long chain alkylphenols (with allergenic, cytotoxic, mutagenic and tumour-promoting properties) together with the extremely potent allergens, the urushiols. Such hazardous compounds can be present only in very low concentrations in phytopharmaceutical preparations and hence, for the purposes of drug safety, techniques must be available for the identification and quantification of these allergens at extremely low levels in refined manufactured materials. GC-MS analysis of samples collected at various stages during the production process of a standardised extract of G. biloba (EGb 761) demonstrated that all alkylphenols present in the primary acetone extracts were removed in parallel with the same efficiency irrespective of their aromatic substitution pattern. Furthermore, in the final product the content of urushiols was generally below the detection limit of 0.03 ppm. Therefore, it is concluded that demonstrating the absence of the predominant, and easily quantifiable, ginkgolic acids provides a reliable means for the control of pharmaceutical quality of the final product.

Allergens↗
PubMed1992

Biodegradable self-reinforced composite materials; manufacturing structure and mechanical properties.

Biodegradable (or absorbable), self-reinforced polymeric composites fulfill the demands of secure orthopaedic fixation materials because of their high strength, appropriate stiffness and strength retention which can be tailored according to the healing rate of damaged tissues. Ultra-high strength, self-reinforced, macroscopical biodegradable polymeric composites can be manufactured by creating the polymeric microstructure, where oriented reinforcing elements and matrix material, which have the same chemical element composition, are bound together. Biodegradable, self-reinforced composites have attractive application possibilities in surgery. The materials can be processed into the form of rods, screws, tacks, cerclages, clamps, plates, spirals, etc., which have versatile applications in traumatology and in orthopaedic surgery.

Animals↗
PubMed1979

[The use of carbon as manufacturing material of endoprotheses (author's transl)].

According to the present stage of technology, arthroplasties have a change of only short-term to medium-term success quotas despite good initial successes. Permanent healing is restricted because of possible loosening of the prostheses. Even clinically silent loosenings will ultimately lead to failures, either by progressive degeneration of the bones at the supporting points of the prosthesis or through breakage of the stem of the prostheses. Attempts to overcome such difficulties by changing the shape of the prostheses, remain unsuccessful. The material employed in the construction of the prosthesis is certainly of some importance in this connection. Carbon has been known for a long time as a well-tolerated material in implant surgery. Carbon is indeed distinguished by high biocompatibility. The development of new carbons based on graphite which considerably improve its physical properties, has enabled the manufacture of endoprostheses made from carbon. Studies have proved that this substance is nontoxic. There are also no immunological reactions. Abrasion is low, and the abraded particles do not produce any severe inflammatory reactions. Hence, prostheses made from carbon can be employed as combination constructions, using suitable types of carbon in accordance with the required functions.

Biocompatible Materials↗
PubMed2006

Metal-on-metal bearings surfaces: materials, manufacture, design, optimization, and alternatives.

When first introduced, total hip replacements offered pain relief and improved mobility in elderly patients. The success of this procedure in terms of long-term durability and restoration of function has led to its use in younger, more active patients. This has resulted in a commensurate increase in patient expectation regarding longevity and the degree to which function and lifestyle is restored. The bearing surface is a key feature of the performance of replacement joints. It is generally accepted that excessive amounts of wear debris preclude their long-term survivorship and hence there is an ongoing requirement for bearing surfaces which minimize debris generation. The purpose of this paper is to review the factors which affect the performance of so-called metal-on-metal bearings, to compare their performance with that of the other commonly used contemporary alternatives, metal and ceramic articulating against highly cross-linked polyethylene, and ceramic-on-ceramic, and finally to consider the potential solutions offered by new developments such as ceramic-on-metal and coatings applied to metal-on-metal bearings.

Arthroplasty, Replacement, Hip↗
PubMed2003

Potential of pottery materials in manufacturing radioactive waste containers.

Various pottery materials were evaluated for possible use in manufacturing containers for radioactive waste. Their potential was examined from the viewpoints of the effectiveness of disposal and the changes induced in them by gamma rays. Samples of these materials were irradiated with high-energy neutrons and gamma rays in a reactor near its core. the physical and mechanical properties of the materials before and after gamma irradiation (in a 60Co gamma cell) were compared. The study showed that pottery materials are resistant to radiation. Therefore, they were proposed for manufacturing drums for disposal of radioactive waste of high gamma activity.

Journal Article↗
PubMed2004

Life cycle assessment part 1: framework, goal and scope definition, inventory analysis, and applications.

Sustainable development requires methods and tools to measure and compare the environmental impacts of human activities for the provision of goods and services (both of which are summarized under the term "products"). Environmental impacts include those from emissions into the environment and through the consumption of resources, as well as other interventions (e.g., land use) associated with providing products that occur when extracting resources, producing materials, manufacturing the products, during consumption/use, and at the products' end-of-life (collection/sorting, reuse, recycling, waste disposal). These emissions and consumptions contribute to a wide range of impacts, such as climate change, stratospheric ozone depletion, tropospheric ozone (smog) creation, eutrophication, acidification, toxicological stress on human health and ecosystems, the depletion of resources, water use, land use, and noise-among others. A clear need, therefore, exists to be proactive and to provide complimentary insights, apart from current regulatory practices, to help reduce such impacts. Practitioners and researchers from many domains come together in life cycle assessment (LCA) to calculate indicators of the aforementioned potential environmental impacts that are linked to products-supporting the identification of opportunities for pollution prevention and reductions in resource consumption while taking the entire product life cycle into consideration. This paper, part 1 in a series of two, introduces the LCA framework and procedure, outlines how to define and model a product's life cycle, and provides an overview of available methods and tools for tabulating and compiling associated emissions and resource consumption data in a life cycle inventory (LCI). It also discusses the application of LCA in industry and policy making. The second paper, by Pennington et al. (Environ. Int. 2003, in press), highlights the key features, summarises available approaches, and outlines the key challenges of assessing the aforementioned inventory data in terms of contributions to environmental impacts (life cycle impact assessment, LCIA).

Conservation of Natural Resources↗
PubMed2003

Constrained optimization for green engineering decision-making.

Green engineering requires the designer to consider a very extensive set of environmental impacts. To minimize these impacts, the designer must significantly expand his or her "toolset" of product design concepts, alternative materials, manufacturing systems, and analytic methods for addressing life cycle impacts. This can overwhelm a designer, who then resorts to overly simplistic rules or checklists out of necessity. The central issue is how to identify all "pollution prevention pays" opportunities and then how to deal with the unavoidable tradeoffs that arise after all these opportunities have been exhausted. This paper presents a framework for employing mathematical decision modeling toward this end. A domain-independent constrained optimization formulation is presented. A multiattribute utility function reflects the willingness to pay for environmental improvement and is the basis of the objective function. The feasibility constraints reflect the unavoidable tradeoffs. Several case studies are presented, including power systems, floor tile manufacturing, and computer systems.

Computers↗
PubMed1989

Mortality among employees of an Ontario factory manufacturing insulation materials from amosite asbestos.

The mortality of workers from an Ontario factory manufacturing amosite asbestos insulation materials under poorly controlled environmental conditions is reported here. Seven (58%) of 12 deaths among exposed workers 10 or more years after first exposure were due to malignancies; four (25%) were from lung cancer, and there were two deaths from peritoneal mesothelioma. Those dying from mesothelioma were 47 and 49 years of age. Three (25%) of 12 deaths were from respiratory disease, two were attributed to asbestosis (in men 42 and 53 years of ages), and one to pneumonia in a 54-year-old male.

Asbestosis↗
PubMed2002

Abatement of waste gases and water during the processes of semiconductor fabrication.

The purpose of this article is to examine the methods and equipment for abating waste gases and water produced during the manufacture of semiconductor materials and devices. Three separating methods and equipment are used to control three different groups of electronic wastes. The first group includes arsine and phosphine emitted during the processes of semiconductor materials manufacture. The abatement procedure for this group of pollutants consists of adding iodates, cupric and manganese salts to a multiple shower tower (MST) structure. The second group includes pollutants containing arsenic, phosphorus, HF, HCl, NO2, and SO3 emitted during the manufacture of semiconductor materials and devices. The abatement procedure involves mixing oxidants and bases in an oval column with a separator in the middle. The third group consists of the ions of As, P and heavy metals contained in the waste water. The abatement procedure includes adding CaCO3 and ferric salts in a flocculation-sedimentation compact device equipment. Test results showed that all waste gases and water after the abatement procedures presented in this article passed the discharge standards set by the State Environmental Protection Administration of China.

Air Pollutants↗
PubMed1992

Proficiency testing linked to the national reference system for the clinical laboratory: a proposal for achieving accuracy.

I propose using proficiency testing (PT) to achieve one of the important goals of CLIA: accurate and reliable clinical testing. Routine methods for the clinical laboratory are traceable to Definitive (DM) or Reference Methods (RM) or to Methodological Principles (MP) through a modification of the National Reference System for the Clinical Laboratory. PT is the link used to monitor consistent field performance. Although PT has been effective as a relative measure of laboratory performance, the technical limitations of PT fluids and of routine methods currently in use make it unlikely that PT alone can be used as a reliable measure of laboratory accuracy. Instead, I recommend calibration of routine systems through correlation to DM, RM, or MP with use of patients' specimens. The manufacturer is in the best position to assume this responsibility because of also being responsible for consistent, reliable product. Analysis of different manufactured batches of reagent would be compared with predetermined goals for precision and accuracy, as illustrated with data from product testing of Kodak Ektachem clinical chemistry slides. Adoption of this proposal would give manufacturers of PT materials, manufacturers of analytical systems, PT providers, and government agencies time to understand and resolve sources of error that limit the utility of PT for the job required by law.

Chemistry, Clinical↗
PubMed2007

Combustion synthesis of porous biomaterials.

This article discusses the unique material manufacturing process of self-propagating high temperature synthesis (SHS) as applied to the making of porous biomaterials. Porous materials have long been considered as the first step toward in-vivo bone tissue engineering and the creation of patient life-time implants. The authors have approached this challenge by utilizing combustion synthesis, to create novel materials such as NiTi + TiC as well as porous forms of materials that are commonly accepted for biomedical applications such as tricalcium phosphate and hydroxyapatite. In the SHS product, physico-chemical properties are controlled by, but not limited to, reactant stoichiometry; green density; particle size of the reactant mix; use or presence of a gasifying agent; heating rate of the reactants and gravity. By balancing these parameters, the energy of the reaction is controlled to create the desired product stoichiometry, porosity, and mechanical properties. SHS provides a means to rapidly manufacture materials, saving time and production costs as well as enabling the synthesis of custom devices through the use of individual molds. Mold materials can range from graphite to paper or paper machete. Combustion synthesis offers a method for the rapid manufacture of affordable, individual biomedical devices that will reduce patient recovery time.

Biocompatible Materials↗
PubMed1989

Mortality among employees of an Ontario factory that manufactured construction materials using chrysotile asbestos and coal tar pitch.

This paper describes mortality in a cohort of 324 men exposed to chrysotile asbestos and coal tar pitch used in the manufacture of electrical conduit pipe from a mixture of newsprint, bentonite, and asbestos. One death in a factory worker was attributed to pleural mesothelioma, and long-term employees experienced an increased risk of lung cancer (Standardized Mortality Ratio (SMR) 221; six deaths) and non-malignant respiratory disease (SMR 215; four deaths). In a case-control analysis, men whose jobs involved adding asbestos to the mix of raw materials were found to have a risk of lung cancer sevenfold higher (lower 95% confidence limit: 2.3) than men who had never worked at this job. Exposure to coal tar pitch is presumed to be responsible for the death of one worker from squamous cell carcinoma of the scrotum.

Adult↗