We report measurements taken in Houston, Texas of the chemical composition and degree of hydration of haze particles and compare these results with previously reported measurements taken in rural Virginia. Our in-situ...
We report measurements taken in Houston, Texas of the chemical composition and degree of hydration of haze particles and compare these results with previously reported measurements taken in rural Virginia. Our in-situ, real time measurements are based on detecting changes in particle light scattering extinction with changes in relative humidity and air temperature. With these methods we can determine fine particle mass and sulfate mass concentrations, and sulfate to ammonium ion molar ratio. In Houston, fine particle sulfate averaged 42 % of fine particle mass and the composition in terms of ammonium to sulfate molar ratio ranged from 0.5 to 2 with strong diurnal variation. The particles were most acid during the period 1500 to 2000 and neutral during 0200 to 0900. About 1 3 of the time the particles were droplets supersaturated in terms of salt content. In Virginia, the particles were on average more acidic and contained more water than those in Houston, but the particles were never observed to be supersaturated solution droplets. The difference in the hygroscopic behavior of the particles at the two sites is consistent with differences in both particle chemistry and ambient relative humidity.
作者：
ZABORSKY, OROskar R. Zaborsky
Ph.D. is a program director in the Division of Chemical and Process Engineering of the National Science Foundation 1800 G Street Washington DC 20550. The views conclusions and recommendations expressed herein are those of the author and do not necessarily reflect the views and policies of the National Science Foundation.REFERENCES Conference on "Genetic Control of Environmental Pollutants" July 31-August 3 1983 University of Washington School of Public Health & Community Medicine and Department of Environmental Health Seattle WA. The proceedings are to be published by Plenum Press.Recent reports covering the handling of hazardous industrial wastes including biological processes are (a) "Management of Hazardous Industrial Wastes: Research and Development Needs" National Research Council National Academy Press Washington D.C. 1983 (b) "Technologies and Management Strategies for Hazardous Waste Control
" Congress of the United States Office of Technology Assessment Washington D.C. 1983.An expanded report on the technology market analysis regulatory and legislative factors dealing with biotechnology applications to hazardous wastes has been produced by Dr. Thomas O.Peyton AmTech Consultants Vienna VA for the OTA study.Baross J.A. and Deming J.W.1983. Growth of 'black smoker' bacteria at temperatures of at least 250C. Nature303: 423-426.|Article|ISI|ChemPort|
The potential use of rudders as anti-roll devices has long been recognized. However, the possible interference of this secondary function of the rudder with its primary role as the steering mechanism has prevented, fo...
The potential use of rudders as anti-roll devices has long been recognized. However, the possible interference of this secondary function of the rudder with its primary role as the steering mechanism has prevented, for many years, the development of practical rudder roll stabilizers. The practical feasibility of rudder roll stabilization has, however, in recent years been demonstrated by two systems designed and developed for operational evaluation aboard two different U.S. C oast G uard Cutters, i.e., Jarvis and Mellon of the 3,000-ton, 378-foot HAMILTON Class. The authors describe the major components of the rudder roll stabilization (RRS) system, along with the design goals and methodology as applied to these first two prototypes. In addition, a brief history of the hardware development is provided in order to show some of the lessons learned. The near flawless performance of the prototypes over the past four years of operational use in the North Pacific is documented. Results from various sea trials and reports of the ship operators are cited and discussed. The paper concludes with a discussion of the costs and benefits of roll stabilization achieved using both a modern anti-roll fin system, as well as two different performance level RRS systems. The benefits of roll stabilization are demonstrated by the relative expansion in the operational envelopes of the USS OLIVER HAZARD PERRY (FFG-7) Class. The varying levels of roll stabilization suggest that the merits of fins and RRS systems are strongly dependent on mission requirements and the environment. The demonstrated performance of the reliable RRS system offers the naval ship acquisition manager a good economical stabilization system.
作者：
KORWEK, ELEdward L. Korwek
Ph.D. J.D. is associated with the law offices of Keller and Heckman 1150 17th St. N.W. Washington D.C. 20036.REFERENCES Committee on Recombinant DNA "Potential Biohazards of Recombinant DNA Molecules" Nature250: 175 (1974) Proc. Nat. Acad. Sci.71: 2593 (1974)Science185: 303 (1974).|Article|Fed. Regist.48: 24556 (1983).Milewski
E. Editor's Note. Recombinant DNA Tech. Bull.4: i (1981).Inside EPA 4 1 (1983). EPA has already held a meeting and published a draft report on the subject of its regulation of this area under the TSCA. EPA "Administrator's Toxic Substances Advisory Committee Meeting"
Fed. Regist.48: 8342 (1983) Regulation of Genetically Engineered Substances Under TSCA
Chemical Control Division Office of Toxic Substances Office of Pesticides and Toxic Substances Environmental Protection Agency Washington D.C. (March 1982). Congress also recently held a hearing on the subject of existing federal authority over the release of R-DNA-containing organisms into environment. M. Sun Science221: 136 (1983).Sects. 2-30 15 U.S. Code sects. 2601-2629 (1976 and Supp. V 1981). Hereinafter all references in the text to TSCA refer to the section numbers as enacted and not to the corresponding U.S. Code sections.The Administrative Procedure Act specifically states that the reviewing court shall "hold unlawful and set aside agency action findings and conclusions found to be hellip in excess of statutory jurisdiction
authority or limitations or short of statutory right. hellip " 5 U.S. Code
sect. 706(2)(C) (1976).PHS Act 42 U.S. Code sects. 217a and 241 (1976) Charter
Recombinant DNA Advisory Committee Department of Health and Human Services (1982).Korwek E. Food Drug and Cosm. L. J.35: 633 (1980) p. 636.Although DHHS has some authority under Section 361 of the PHS Act to regulate R-DNA materials that cause human disease and are communicable most types of experimentation would not fall into this category. Because of this limitation the Sub committee of the Federal
A new technique has been developed for determination of optical depths δa as low as 0.0005 for thin layers of absorbing materials or particles. The measurement involves optical amplification of the absorption and is ...
详细信息
A new technique has been developed for determination of optical depths δa as low as 0.0005 for thin layers of absorbing materials or particles. The measurement involves optical amplification of the absorption and is not affected by the scattering properties of the absorber. This is accomplished by introducing the absorber into the virtually isotropic radiation field between two high-reflectance diffusing wafers and measuring the resultant attenuation of the transmitted light. The technique has been directed toward determination of the absorption coefficient of atmospheric aerosols in remote and relatively unpolluted locations. Provided appropriate collection filters and sampling conditions are used, the method can establish an absorption coefficient for the aerosol as low as 5 × 10?9 m?1 within a 10-h sampling period. A proportionally higher absorption coefficient requires proportionally less sample time. This paper discusses instrument design, the theoretical optical model, laboratory calibration, and a field test of the technique.
Optical properties of Nuclepore filter media, as used in the integrating plate (IP) method for determination of aerosol light absorption, have been examined. It has been shown that the internal reflectance is high for...
详细信息
Optical properties of Nuclepore filter media, as used in the integrating plate (IP) method for determination of aerosol light absorption, have been examined. It has been shown that the internal reflectance is high for the Nuclepore filters typically used and that changes in this value result in spurious contributions to absorption measurements. It has been found that aerosol particles on the filter surface can substantially alter the internal reflection coefficient of this material for a wide variety of aerosol types. The amount and nature of this change are found to vary with optical and physical properties of the aerosol in contact with the filter surface. A simple mathematical model of the optical system is described that allows for variations in Nuclepore internal reflectance. Implications of this model and data suggest that light absorption measurements as determined via the IP method may be systematically overestimated for certain samples by as much as 30%. Estimates of the magnitude of this inaccuracy for a given IP absorption measurement are presented based on the model and supplementary back reflectance measurements.
Results from laboratory equilibration studies indicate that sediment-adsorbed 2,4,5,2′,4′,5′-hexachlorobiphenyl (HCBP) fractions may be comprised of both reversibly and strongly bound or resistant components. This ...
Internal loading of P was implicated as a major eutrophicating factor in Long Lake, Washington (Kitsap County) [USA]. As a result of such loading, summer total P concentrations approach or exceed 100 .mu.g P l-1. Most...
Internal loading of P was implicated as a major eutrophicating factor in Long Lake, Washington (Kitsap County) [USA]. As a result of such loading, summer total P concentrations approach or exceed 100 .mu.g P l-1. Most of the summer loading of P is thought to have been released directly from the rich, flocculent sediment in the mid and northern part of the lake as a result of high pH (up to 10) related to phytoplankton photosynthesis. The lake also supports a dense submersed macrophyte crop (areal weighted mean dry weight of .apprx. 220 g m-2) composed primarily of Elodea densa. Although excretion of P from healthy E. densa was minimal, the potential contribution of P indirectly from sediment via macrophyte uptake and subsequent decomposition in the winter was on the order of 200-400 kg yr-1 or .apprx. 25-50% of the external loading. Nevertheless, loading of P during predrawdown summers is thought to have originated largely as a direct release from sediment due to high pH. Estimates of sediment P release determined from laboratory experiments, mass balance and core analyses ranged from 2.2-5.6 mg m-2 day-1. As a component of the restoration program, the lake (mean depth of 2 m) was drawn down nearly 2 m for 4 mo. during the summer and fall of 1979. The lake''s trophic status was expected to improve due to sediment consolidation and/or macrophyte reduction. The drawdown resulted in an 84% reduction in macrophyte biomass in 1980 but minimal sediment consolidation (0.1 m). Winter decomposition of the much smaller macrophyte crop, apparently provided insufficient P in the spring to stimulate phytoplankton and to enrich midlake sediments, which has probably occurred in previous years. Low water column pH during the postdrawndown summer of 1980 resulted from relatively low rates of plankton photosynthesis. During the summer of 1980 internal loading of P was reduced and total P remained below 50 .mu.g l-1.
暂无评论