Two recent intratracheal instillation toxicology studies in rats clearly show that a naturally occurring quartz, with occluded crystal surfaces (quartz isolate), produced significantly less inflammatory response than a crushed reference quartz (DQ12). Respirable-size quartz isolate was isolated from bentonite parent rock, without crushing or the use of chemicals, to ensure that the surface prop...

This paper describes an architecture that provides support for quality of service (QoS) in open systems. The Quartz QoS architecture aims to avoid the dependency on specific platforms that limits the application of most existing QoS architectures in open, heterogeneous and distributed systems. Quartz adopts a flexible and extensible platform-independent design that allows its internal component...

In this paper, we propose a new multivariate signature scheme named MI-T-HFE as a competitor of QUARTZ. The core map of MI-T-HFE is of an HFEv type but more importantly has a specially designed trapdoor. This special trapdoor makes MI-T-HFE have several attractive advantages over QUARTZ. First of all, the core map and the public map of MI-T-HFE are both surjective. This surjectivity property is...

BACKGROUND Determination of quartz by Fourier transform infrared spectrometry (FTIR) is not specific: the obtained results are influenced by matrix components, some of which cause spectral interference. The aim of the study was to evaluate the effect of dust components responsible for spectral interference with quartz on the results of its determinations, and to develop methods to minimize the ...

AIMS To reanalyse exposure-response data from a Scottish colliery to gain a more detailed knowledge of the relations between exposure to quartz and risks of silicosis in coal miners, and hence inform the debate on an appropriate occupational standard for respirable quartz. METHODS Detailed data on working times at different quartz concentrations were combined to produce exposure profiles for ...

A further comparison of the Health and Safety Executive (HSE) standard quartz, A9950 (Sikron F600), and the National Institute of Standards and Technology (NIST) Standard Reference Material (SRM) 1878, standard respirable alpha-quartz, has been carried out for the four principal diffraction peaks. In the earlier comparison by Jeyaratnam and Nagar (1993, Ann Occup Hyg; 37: 167-79), the standards...

The X-ray diffraction method and the phosphoric acid method are widely used to determine the fraction of free silica (mainly quartz and other silica polymorphs) in respirable dust sampled in working environments in Japan. In this study, we clarified the size effect of quartz dust for the X-ray diffraction method and the phosphoric acid method using size controlled quartz samples. The quartz sam...

molybdenite occurs in five forms in the sar cheshmeh porphyry copper deposit, namely, (1)-veinlets with quartz-molybdenite, (2)-veinlets with quartz-molydenite that were filled with pyrite, (3)-veinlets with quartz-molybdenite-pyrite–chalcopyrite, (4)-molybdenite veinlets with very low quartz and (5)-disseminated molybdenite grains. because of their large size, the veinlet-related molybdenite g...

OBJECTIVES Little information is available on the quantitative risks of respiratory disease from quartz in airborne dust in the heavy clay industry. Available evidence suggested that these risks might be low, possibly because of the presence in the dust of other minerals, such as illite and kaolinite, which may reduce the harmful effects of quartz. The aims of the present cross sectional study ...

Introduction: Research into the origin of color of common varieties of quartz has shown that many longheld beliefs regarding the origin of the colored varieties are incorrect. In particular, the widely stated role of rutile inclusions in the coloration of rose and blue quartz must now be re-evaluated on the basis of new studies. Rose Quartz: Spectroscopic studies have shown that the color of ro...