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Page : 5 pages
File Size : 28,25 MB
Release : 1993
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During the last year, three projects were completed: a high resolution spectroscopic study of CH stretch of HCCN, measurement of rate constant of reaction between ethynyl (CCH) and H2 at 295-- 875 K, and measurement of recombination rate of propargyl (CH2CCH) at room temperature. (DLC).
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Page : 13 pages
File Size : 24,42 MB
Release : 1994
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Rate of reaction of ketenyl radical with O2 at room temperature was determined as 6.5(6) × 10-−13 CM3 molecules−1 s−1 and an upper bound of 1 × 10−13 cm3 molecule−1 s−1 was estimated for the reaction rate of acetylene with ketenyl. The high resolution spectrum of the [nu]1 acetylenic CH stretch of propargy1 radical (HCCCH2) near 3322 cm−1 has obtained and analyzed. Nuclear spin weights demonstrate that the CH2 hydrogen atoms are in the carbon atom plane. We have attempted to measure the propargy1 recombination rate constant at 296 K; however, the observed rate constant of (1.2×0.2) x 10−1° cc-molecule−1-s−1 may be affected by other reactions. The CH stretch fundamental, [nu]1, of HCCN has been observed, assigned, and analyzed. Analysis of the hot bands associated with bending shows that HCCN is a quasilinear molecule with a very floppy potential function for the HCC bending angle. The barrier to linearity is estimated to be about 100 cm−1. Rate of the reaction between C2H and H2 has been measured at 295--855 K. The rate constant exhibited a non-Arrhenius form well represented by k = (9.44±0.50) × 10−14T{sup 0.9}exp( -1003±40/T)cm3molecule−1s−1. The reaction between atomic oxygen and the amidogen radical, NH2 has been studied at 295 K; the room temperature rate constant was measured as (6.5 ± 1.3) × 10−1 s−1. The minor channel leading to NH + OH was observed but accounted for at most about 8% of the NH2 reacting. The rate constant for the reaction NH+O was determined from fitting the NH time profile to be 6.6±1011 cm3 molecule−1 s−1.
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Page : 7 pages
File Size : 42,17 MB
Release : 1995
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This research was directed at the detection, monitoring, and study (by infrared absorption spectroscopy) of the chemical kinetic behavior of small free radical species thought to be important intermediates in combustion. The work typically progressed from the detection and analysis of the infrared spectrum of combustion radical to the utilization of the infrared spectrum thus obtained in the investigation of chemical kinetics of the radical species. The methodology employed was infrared kinetic spectroscopy. In this technique the radical is produced by UV flash photolysis using an excimer laser and then its transient infrared absorption is observed using a single frequency cw laser as the source of the infrared probe light. When the probe laser frequency is near the center of an absorption line of the radical produced by the flash, the transient infrared absorption rises rapidly and then decays as the radical reacts with the precursor or with substances introduced for the purpose of studying the reaction kinetics or with itself. The decay times observed in these studies varied from less than one microsecond to more than one millisecond. By choosing appropriate time windows after the flash and the average infrared detector signal in a window as data channels, the infrared spectrum of the radical may be obtained. By locking the infrared probe laser to the center of the absorption line and measuring the rate of decay of the transient infrared absorption signal as the chemical composition of the gas mixture is varied, the chemical kinetics of the radical may be investigated. In what follows the systems investigated and the results obtained are outlined.
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Page : 782 pages
File Size : 18,86 MB
Release : 1995
Category : Power resources
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Page : pages
File Size : 40,55 MB
Release : 2004
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This research was directed at the detection, monitoring, and study of the chemical kinetic behavior by infrared absorption spectroscopy of small free radical species thought to be important intermediates in combustion. Work on the reaction of OH with acetaldehyde has been completed and published and work on the reaction of O(1D) with CH4 has been completed and submitted for publication. In the course of our investigation of branching ratios of the reactions of O(1D) with acetaldehyde and methane, we discovered that hot atom chemistry effects are not negligible at the gas pressures (13 Torr) initially used. Branching ratios of the reaction of O(1D) with CH4 have been measured at a tenfold higher He flow and fivefold higher pressure.
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Page : 5 pages
File Size : 22,16 MB
Release : 1993
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During the last year, three projects were completed: a high resolution spectroscopic study of CH stretch of HCCN, measurement of rate constant of reaction between ethynyl (CCH) and H[sub 2] at 295-- 875 K, and measurement of recombination rate of propargyl (CH[sub 2]CCH) at room temperature. (DLC).
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Page : 702 pages
File Size : 17,94 MB
Release : 1995
Category : Aeronautics
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Author : Gerry E. Hendershot
Publisher :
Page : 982 pages
File Size : 38,9 MB
Release : 1988
Category : Birth control
ISBN : 9780840602220
The 1982 statistics on the use of family planning and infertility services presented in this report are preliminary results from Cycle III of the National Survey of Family Growth (NSFG), conducted by the National Center for Health Statistics. Data were collected through personal interviews with a multistage area probability sample of 7969 women aged 15-44. A detailed series of questions was asked to obtain relatively complete estimates of the extent and type of family planning services received. Statistics on family planning services are limited to women who were able to conceive 3 years before the interview date. Overall, 79% of currently mrried nonsterile women reported using some type of family planning service during the previous 3 years. There were no statistically significant differences between white (79%), black (75%) or Hispanic (77%) wives, or between the 2 income groups. The 1982 survey questions were more comprehensive than those of earlier cycles of the survey. The annual rate of visits for family planning services in 1982 was 1077 visits /1000 women. Teenagers had the highest annual visit rate (1581/1000) of any age group for all sources of family planning services combined. Visit rates declined sharply with age from 1447 at ages 15-24 to 479 at ages 35-44. Similar declines with age also were found in the visit rates for white and black women separately. Nevertheless, the annual visit rate for black women (1334/1000) was significantly higher than that for white women (1033). The highest overall visit rate was for black women 15-19 years of age (1867/1000). Nearly 2/3 of all family planning visits were to private medical sources. Teenagers of all races had higher family planning service visit rates to clinics than to private medical sources, as did black women age 15-24. White women age 20 and older had higher visit rates to private medical services than to clinics. Never married women had higher visit rates to clinics than currently or formerly married women. Data were also collected in 1982 on use of medical services for infertility by women who had difficulty in conceiving or carrying a pregnancy to term. About 1 million ever married women had 1 or more infertility visits in the 12 months before the interview. During the 3 years before interview, about 1.9 million women had infertility visits. For all ever married women, as well as for white and black women separately, infertility services were more likely to be secured from private medical sources than from clinics. The survey design, reliability of the estimates and the terms used are explained in the technical notes.
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Page : 1420 pages
File Size : 33,13 MB
Release : 199?
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Author : Advisory Committee on Technology and Society
Publisher : National Academies Press
Page : 1298 pages
File Size : 10,29 MB
Release : 1989
Category : Social Science
ISBN : 9780309037860
Cities and Their Vital Systems asks basic questions about the longevity, utility, and nature of urban infrastructures; analyzes how they grow, interact, and change; and asks how, when, and at what cost they should be replaced. Among the topics discussed are problems arising from increasing air travel and airport congestion; the adequacy of water supplies and waste treatment; the impact of new technologies on construction; urban real estate values; and the field of "telematics," the combination of computers and telecommunications that makes money machines and national newspapers possible.
