Showing papers by "Cabot Corporation published in 1989"

Comparison of the noise attenuation of three audiometric earphones, with additional data on masking near threshold.

Abstract: The noise‐excluding properties of a standard supra‐aural audiometric earphone, a widely used circumaural‐supra‐aural combination, and an insert earphone sealed to the ear with a vinyl foam eartip were measured in a diffuse‐field room complying with ANSI S12.6‐1984. Data on attenuation were obtained monaurally with the nontest ear plugged and muffed. Results for the supra‐aural earphones generally agreed well with previously reported measurements. A broadband masking noise was used to directly test the ANSI S3.1‐1977 permissible background noise levels for measuring to audiometric zero using standard audiometric earphones. This ‘‘ANSI noise’’ raised the average thresholds of 15 normal‐hearing test subjects by 3 to 5 dB at the octave frequencies from 500 to 4000 Hz. With a noise conforming to the less stringent OSHA‐1983 regulation, average thresholds were elevated 9 to 17 dB. An ‘‘ENT office noise’’ with an overall sound level of 54 dBA raised average thresholds even further, by as much as 29 dB at 500 Hz. Use of the circumaural system in the office noise limited the threshold elevation to 11, 5, 2, and 0 dB at the four octave frequencies tested. With the fully (‘‘deeply’’) inserted foam eartips, the threshold elevation in the simulated office noise was 2 dB or less at all test frequencies. Actual threshold elevations agreed closely with predictions based on a critical ratio calculation utilizing measured sound field noise levels and measured earphone attenuation values.

Controlling the oxygen content in tantalum material

Abstract: A process for controlling the oxygen content in tantalum material comprising heating the material under a hydrogen-containing atmosphere in the presence of a getter composite comprising a getter metal encapsulated in tantalum.

Method for controlling the oxygen content of tantalum material

Abstract: A process for controlling the oxygen content in tantalum material comprising heating the material under a hydrogen-containing atmosphere in the presence of a tantalum getter metal having an initial oxygen content lower than the tantalum material.

Pulmonary alveolar proteinosis and cement dust: a case report.

Abstract: Pulmonary alveolar proteinosis developed in a 29-year-old white man within 2 years of working as a cement truck driver. Pulmonary alveolar proteinosis (PAP), an uncommon respiratory disorder characterized by the accumulation of phospholipid material within the alveoli, has been described in association with exposure to silica, aluminum oxide, and a variety of dusts and fumes. Although a link between exposure to Portland cement and PAP has not been previously noted, this type of cement contains nearly 20% silica. Lung biopsy material, originally used to diagnose PAP, was reviewed under electron dispersive spectroscopy. Analysis indicated the presence of silica particles within the alveolar fluid and macrophages. A number of items support a causal relationship between exposure to cement dust and PAP: (1) the temporal sequence between assuming job duties and the development of the illness, (2) improvement following removal from further exposure, (3) dusty, unprotected working conditions, (4) the presence of silica within the cement, and (5) the alveolar fluid from periodic acid-Schiff-positive lung tissue.

Aqueous colloidal dispersion of fumed silica without a stabilizer

Abstract: A stable non-dilatant aqueous colloidal dispersion of fumed silica, without a stabilizer, having a fumed silica concentration of at least about 35% by weight. Also disclosed is a process for producing aqueous colloidal dispersions of fumed silica, without a stabilizer, which are stable and non-dilatant.

Cleaning apparatus and process

Abstract: Particles adhering to the internal surfaces of an object are removed by the movement of a shock wave past the surfaces. The shock wave is generated by the explosion of a gas in a chamber located inside the object. The invention has particular application for use in cleaning process equipment.

High surface area metal oxide foams and method of producing the same

Abstract: The present invention includes metal oxide foam particles and a method of making the same. A decomposable metal salt feed solution is injected into a hot atomizing gas. The mixture of hot atomizing gas and feed solution is maintained in the reactor until the feed solution converts to metal oxide foam particles. The metal oxide foam particles have a high specific surface area.

Line coupling device

Abstract: There is disclosed herein a line coupling device whose coupling function is achieved by interleaving of plural elongate latching members bearing teeth thereon. The elongate latching members are supported in a member such that the coupling device may be readily coupled and uncoupled.

Drug testing: Technical complications of a complex social issue

Abstract: To control the adverse effects of substance abuse, urinary drug testing has become common practice in some occupational settings. Although it is virtually impossible to assess accurately the impact of drug abuse at work, increased accidents and absenteeism as well as impaired productivity have been attributed to drug abuse. The major analytical techniques used to screen for illegal drug use are thin-layer chromatography and enzyme- and radioimmunoassays. Gas chromatography-mass spectrometry is uniformly recommended to confirm any positive screening test. The major technical problem in interpreting screening tests is that the presence of a substance in the urine indicates merely exposure to the drug, not necessarily intoxication, habituation, or addiction. Since no certifying criteria are available to insure quality control among laboratories performing urinary drug testing, results may vary widely. In fact, a study conducted by the Centers for Disease Control suggests that poor performance of some laboratories may adversely affect the treatment of drug abuse. The Federal Rehabilitation Act (1973, section 504) prohibits discrimination against the handicapped, which includes both drug abuse and alcoholism. Legal challenges to urinary drug testing have focused on issues related to the right to privacy and freedom from unreasonable searches. Because of the wide-ranging legal, ethical, and medical ramifications of drug-screening programs, careful review of these issues is recommended before an organization establishes such a program.

Correlating microstructure and texture in cold-rolled Ta ingot

Abstract: An analysis of tantalum ingot cold-rolled and annealed under different conditions reveals several correlations between the microstructure, developed textures and thermomechanical processing parameters. For example, the hardness of rolled sheet is not significantly affected by the amount of reduction prior to the final anneal, while the final grain size decreases with an increasing number of intermediate annealing steps. Four classes of texture are found in the cold-rolled tantalum, but the finer-grained classes can only be produced via a 70 percent reduction in thickness prior to the final anneal. Although ample dislocation debris is produced by the rolling operation, clearly defined line dislocations and dislocation networks are absent, indicating that full recrystallization is not achieved in the finished sheets. A large concentration of ledge dislocations at the grain boundary regions is considered an important contributor to the good formability of tantalum.

Is it necessary to measure hearing protector attenuation at 3.15 and 6.3 kHz

Abstract: The real‐ear attenuation data for 81 different hearing protectors were analyzed with respect to the errors that would arise if, instead of averaging the 1/3‐octave‐band results at 3.15 and 4 kHz and 6.3 and 8 kHz, respectively, the octave‐band attenuation at 4 and 8 kHz was estimated from only the 1/3‐octave‐band data at those two frequencies. Errors as large as 3–4 dB were found to occur in rare instances, but more typically were in the range of 0.5–1.5 dB. However, in terms of computation of an overall noise reduction rating such as the NRR, the effect of excluding the 3.15‐ and 6.3‐kHz data led to errors that averaged only 0.1 dB and never exceeded 0.3 dB, except in one instance, where the error was 0.6 dB. It was concluded that there is little value in measuring real‐ear attenuation in a diffuse sound field at the frequencies of 3.15 and 6.3 kHz for applications in which hearing protector attenuation data are normally utilized.

Method for measuring non-porous surface area of carbon black

Abstract: An automated method for measuring the non-porous surface area of carbon black is disclosed. The method comprises passing a small sample of a CTAB-carbon black dispersion through a disposable filter to separate the carbon black with adsorbed CTAB from the filtrate containing unadsorbed CTAB. The filtrate next passes through a measuring loop and a high pressure liquid chromatography column to separate the CTAB from the other filtrate components. The CTAB is next sensed by a detector and an integrator calculates the amount of CTAB adsorbed by the carbon black and the non-porous surface area of the carbon black. The integrated apparatus for carrying out this method is also described. Once the carbon black and the CTAB are mixed, there is no further handling of the sample. The system is entirely automated and takes only a few minutes for the CTAB area determination. Measuring temperatures can also be fixed. This results in much more reproducible CTAB numbers for a particular carbon black.

An evaluation of the aluminothermic production of magnesium

Abstract: A process for producing magnesium metal at atmospheric pressure, using aluminum as a reductant, was proposed by Avery (1974). In the bench scale experiments, dolomite and magnesite in varying proportions were reacted with aluminum in the temperature range 1475° to 1700°C with conversion efficiencies up to 86%.

Method of producing alumina foams

Abstract: The present invention relates to alumina oxide particles having an internal foam structure and a method of making the same. The method first creates foam particles of aluminum sulfate and, subsequently, converts the aluminum sulfate to aluminum oxide particles with the same internal foam structure. The aluminum oxide foam particles made by this method have large specific surface areas and pore volumes.

The effects of silicon on the properties of tantalum

Abstract: The microalloying of tantalum with silicon has been effectively used on a commercial scale. However, data on effects of microalloying on processibility, microstructure and mechanical properties are not readily available. To develop some data, tantalum powder with various levels of silicon (0–50 ppm) was processed under identical conditions. Sheet samples were then annealed at different temperatures and evaluated via microstructural, chemical and mechanical tests. The recrystallization temperature was found to increase with silicon content, most probably as a result of the presence of an intermetallic (Ta3Si) phase. The mechanical properties of unrecrystallized tantalum are, as expected, significantly different from those of recrystallized tantalum.

Gravimetric determination of the iodine number of carbon black

Abstract: A gravimetric method for determining the iodine adsorption number of carbon black is disclosed. The concentration of an accurately weighed iodine solution is determined by titrating with a standardized titrant and determining the concentration of the iodine solution by the weight of the standardized titrant needed to reach the titration endpoint. An appropriate amount of accurately weighed iodine solution is mixed with an accurately weighed amount of carbon black, and the mixture is equilibrated. The concentration of the resulting supernatant is determined by determining the weight of the standardized titrant needed to reach the titration endpoint. The iodine adsorption number is then determined based on the gravimetrically determined concentrations of the solutions. Preferably, the method is semi-or fully automated, and an apparatus for accomplishing the same is disclosed.