Note: This page contains sample records for the topic chemical composition chemical from Science.gov.
While these samples are representative of the content of Science.gov,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of Science.gov
to obtain the most current and comprehensive results.
Last update: August 15, 2014.
1

Chemical Composition  

NASA Astrophysics Data System (ADS)

Measurements of the chemical compositions of materials and the levels of certain substances in them are vital when assessing and improving public health, safety and the environment, are necessary to ensure trade equity, and are required when monitoring and improving industrial products and services. Chemical measurements play a crucial role in most areas of the economy, including healthcare, food and nutrition, agriculture, environmental technologies, chemicals and materials, instrumentation, electronics, forensics, energy, and transportation.

May, Willie; Cavanagh, Richard; Turk, Gregory; Winchester, Michael; Travis, John; Smith, Melody; Derose, Paul; Choquette, Steven; Kramer, Gary; Sieber, John; Greenberg, Robert; Lindstrom, Richard; Lamaze, George; Zeisler, Rolf; Schantz, Michele; Sander, Lane; Phinney, Karen; Welch, Michael; Vetter, Thomas; Pratt, Kenneth; Scott, John; Small, John; Wight, Scott; Stranick, Stephan

2

Computing Equilibrium Chemical Compositions  

NASA Technical Reports Server (NTRS)

Chemical Equilibrium With Transport Properties, 1993 (CET93) computer program provides data on chemical-equilibrium compositions. Aids calculation of thermodynamic properties of chemical systems. Information essential in design and analysis of such equipment as compressors, turbines, nozzles, engines, shock tubes, heat exchangers, and chemical-processing equipment. CET93/PC is version of CET93 specifically designed to run within 640K memory limit of MS-DOS operating system. CET93/PC written in FORTRAN.

Mcbride, Bonnie J.; Gordon, Sanford

1995-01-01

3

Aqueous chemical wash compositions  

SciTech Connect

This patent describes an aqueous, substantially unfoamed chemical wash composition having properties making it suitable for use as a pre-flush in well cementing operations and/or for removal of drilling mud from a borehole at a temperature of from about 150/sup 0/F to about 270/sup 0/F, the wash a. being predominantly composed of water, b. containing an active surfactant component comprising a combination of (1) from about 0.1 to about 1.5 weight percent (total weight basis) of a water soluble anionic surfactant; (2) from about 0.1 to about 1.5 weight percent (total weight basis) of a nonionic surfactant; and (3) from about 0.05 to about 0.54 weight percent (total weight basis) of at least one water soluble amphoteric surfactant, and c. having dispersed therein a heterogeneous mixture of distinct particles comprising both a first particulate oil soluble resin which is friable and a second particulate oil soluble resin which is pliable and where the size of the friable resin particles ranges from about 0.5 to about 300 microns and the size of the pliable resin particles ranges from about 0.05 to about 30 microns. The amount of the friable-pliable resin mixture is sufficient to impart effective fluid loss control to the chemical wash composition.

Bannister, C.E.

1987-07-21

4

Method of forming a chemical composition  

DOEpatents

A method of forming a chemical composition such as a chemical hydride is described and which includes the steps of selecting a composition having chemical bonds and which is capable of forming a chemical hydride; providing a source of hydrogen; and exposing the selected composition to an amount of ionizing radiation to encourage the changing of the chemical bonds of the selected composition, and chemically reacting the selected composition with the source of hydrogen to facilitate the formation of a chemical hydride.

Bingham, Dennis N. (Idaho Falls, ID) [Idaho Falls, ID; Wilding, Bruce M. (Idaho Falls, ID) [Idaho Falls, ID; Klingler, Kerry M. (Idaho Falls, ID) [Idaho Falls, ID; Zollinger, William T. (Idaho Falls, ID) [Idaho Falls, ID; Wendt, Kraig M. (Idaho Falls, ID) [Idaho Falls, ID

2007-10-09

5

Chemical Composition of Cigarette Smoke.  

National Technical Information Service (NTIS)

Cigarette smoke is a concentrated aerosol of liquid particles suspended in an atmosphere consisting mainly of nitrogen, oxygen, and carbon dioxide. While the precise chemical composition of the particulate and gaseous phases is dependent on the characteri...

M. R. Guerin

1979-01-01

6

Chemical composition of Mars  

USGS Publications Warehouse

The composition of Mars has been calculated from the cosmochemical model of Ganapathy and Anders (1974) which assumes that planets and chondrites underwent the same 4 fractionation processes in the solar nebula. Because elements of similar volatility stay together in these processes, only 4 index elements (U, Fe, K and Tl or Ar36) are needed to calculate the abundances of all 83 elements in the planet. The values chosen are U = 28 ppb, K = 62 ppm (based on K U = 2200 from orbital ??-spectrometry and on thermal history calculations by Tokso??z and Hsui (1978) Fe = 26.72% (from geophysical data), and Tl = 0.14 ppb (from the Ar36 and Ar40 abundances measured by Viking). The mantle of Mars is an iron-rich [Mg/(Mg + Fe) = 0.77] garnet wehrlite (?? = 3.52-3.54 g/cm3), similar to McGetchin and Smyth's (1978) estimate but containing more Ca and Al. It is nearly identical to the bulk Moon composition of Morgan et al. (1978b). The core makes up 0.19 of the planet and contains 3.5% S-much less than estimated by other models. Volatiles have nearly Moon-like abundances, being depleted relative to the Earth by factors of 0.36 (K-group, Tcond = 600-1300 K) or 0.029 (Tl group, Tcond < 600 K). The water abundance corresponds to a 9 m layer, but could be higher by as much as a factor of 11. Comparison of model compositions for 5 differentiated planets (Earth, Venus, Mars, Moon, and eucrite parent body) suggests that volatile depletion correlates mainly with size rather than with radial distance from the Sun. However, the relatively high volatile content of shergottites and some chondrites shows that the correlation is not simple; other factors must also be involved. ?? 1979.

Morgan, J. W.; Anders, E.

1979-01-01

7

Chemical composition of cigarette smoke  

Microsoft Academic Search

Cigarette smoke is a concentrated aerosol of liquid particles suspended in an atmosphere consisting mainly of nitrogen, oxygen, and carbon dioxide. While the precise chemical composition of the particulate and gaseous phases is dependent on the characteristics of the cigarette and the manner in which it is smoked, both phases contain tens of hundreds of individual constitutents. Notable among potentially

Guerin

1979-01-01

8

Chemical recycling of scrap composites  

NASA Technical Reports Server (NTRS)

There are no well-developed technologies for recycling composite materials other than grinding to produce fillers. New approaches are needed to reclaim these valuable resources. Chemical or tertiary recycling, conversion of polymers into low molecular weight hydrocarbons for reuse as chemicals or fuels, is emerging as the most practical means for obtaining value from waste plastics and composites. Adherent Technologies is exploring a low-temperature catalytic process for recycling plastics and composites. Laboratory results show that all types of plastics, thermosets as well as thermoplastics, can be converted in high yields to valuable hydrocarbon products. This novel catalytic process runs at 200 C, conversion times are rapid, the process is closed and, thus, nonpolluting, and no highly toxic gas or liquid products have been observed so no negative environmental impact will result from its implementation. Tests on reclamation of composite materials show that epoxy, imide, and engineering thermoplastic matrices can be converted to low molecular weight hydrocarbons leaving behind the reinforcing fibers for reuse as composite reinforcements in secondary, lower-performance applications. Chemical recycling is also a means to dispose of sensitive or classified organic materials without incineration and provides a means to eliminate or reduce mixed hazardous wastes containing organic materials.

Allred, Ronald E.; Salas, Richard M.

1994-01-01

9

Chemical Composition of Martian Rocks  

NASA Astrophysics Data System (ADS)

In situ analyses of martian surface rocks (and soils) provided data about the chemical composition of several landing sites. One of the used techniques is the alpha-induced x-ray emission applied by the Alpha Particle X-Ray Spectrometer (APXS) onboard the current Mars Exploration Rovers (MER) Spirit and Opportunity and onboard the preceding Mars Pathfinder Rover Sojourner (MPF Mission). These measurements encompass the determination of major, minor, and (for the MER APXS) trace elements, such as Ni, Zn, and Br, as well as Cu, Pb, Sr, Y, Ga, and Ge. The obtained data indicate a remarkable compositional difference between the rocks at the different landing sites, whereas most soils including those measured by the Viking landers are chemically similar. Initially, the only chemical data of Mars were obtained by the study of a class of meteorites that turned out to be martian, which was furthermore confirmed by the discovery of a rock (by rover Opportunity) that is chemically related to those meteorites. The rocks at the Pathfinder landing site turned out to be richer in Si and K than the martian meteorites and all rocks encountered at the MER sites. At Gusev crater (the first MER landing site), two geological regions were encountered along the rover Spirit's traverse: the plains and the hills. Rocks in the plains resemble primitive basalts, while rocks located in the Columbia Hills revealed different types. Several rock classes could be cataloged based on their chemical composition. Most of the hills rocks are significantly weathered and enriched in mobile elements, such as P, Zn, S, Cl, and Br. On the other hand, a suite of ultramafic rocks was discovered for the first time on Mars. The rocks at Meridiani Planum (the second MER landing site) are salt-rich siliciclastic sediments. All rocks showed much higher S contents than the soils. High concentrations of Cl and Br were also discovered at various samples. Huge quantities of spherules were found on top of soils and outcrops along the rover's traverse. APXS measurements revealed that these spherules contain high amounts of iron that is mainly present as the mineral hematite (determined by Mössbauer spectrometry). The formation of hematite is typically, but not exclusively, an indicator for aqueous activities under oxidizing conditions. The in situ measurements at both MER landing sites point to a variety of sedimentary processes and various types of alteration processes; hence, they show clear evidence of ancient aqueous environments that discontinued long time, ago. The combination of in situ measurements and element correlations obtained by the martian meteorites implies an ancient basaltic crust with high abundances of incompatible elements (K, Rb, Nd, U, and Th) and volatile elements (S, Cl). Compared to the Earth's mantle, the martian mantle contains about twice as much Fe, is richer in moderately volatile elements like K, and has a much higher abundance of phosphorus. In conjunction with chemical data obtained from orbit, such as gamma-ray spectrometry carried out by the Mars Odyssey spacecraft, a global estimation of the composition of the martian surface is obtained and, furthermore, crustal composition can be derived.

Brueckner, J.

2007-05-01

10

The Chemical Composition of Maple Syrup  

ERIC Educational Resources Information Center

Maple syrup is one of several high-sugar liquids that humans consume. However, maple syrup is more than just a concentrated sugar solution. Here, we review the chemical composition of maple syrup. (Contains 4 tables and 1 figure.)

Ball, David W.

2007-01-01

11

Chemical composition of hard-coal pitches  

SciTech Connect

The chemical compositions of the pitches from seven coke and chemicals enterprises working on various charges and their ..gamma.. and ..beta.. components with a quantitative estimation of the individual substances has been investigated by the GLC method. The amount of components of the initial pitches identified ranged between 63 and 78 mass.%, of the ..gamma..-fraction 70-78 mass.%, and of the ..beta..-fraction 47-59 mass.%. The hydrocarbon compositions of the pitches were practically identical, i.e., they did not appear on the composition of the charge.

Chistyakov, A.N.; Denisenko, V.I.

1982-01-01

12

Chemical composition of hard-coal pitches  

SciTech Connect

Gas-liquid chromatography was used to examine the chemical composition of pitches from 7 coking plants operating with different charges, together with their gamma and beta constituents, in an attempt to quantify their individual components. The number of components identified in the original pitches varied between 63 and 78 mass%, 70-78 mass% in the gamma fraction and 47-59 mass% in the beta fraction. The hydrocarbon composition of the pitches remains virtually unchanged, independent of the charge composition.

Chistyakov, A.N.; Denisenko, V.I.

1982-01-01

13

Lunar Skylights and Their Chemical Compositions  

NASA Astrophysics Data System (ADS)

In 2009, the Japanese orbiter, SELenological and Engineering Explorer (SELENE) discovered a skylight on the near side of the moon. Skylights are collapsed ceilings of rilles, thought to be caused by moonquakes, meteoroids, or incomplete formation of these lava tube ceilings. Since then, NASA's Lunar Reconnaissance Orbiter has discovered two more skylights, also located on the near side of the moon. Previous research has shown that the physical characteristics of known rilles, can be used as indicators of the presence of yet undiscovered rille and lava dome locations across the lunar surface. We hypothesize that skylights have a signature chemical composition that is unique, and can be used to predict the location of additional skylights on the surface of the moon. For this study, we compared chemical composition data of the three mare sites containing skylights with the 21 mare sites without skylights. Using the software JMARS for the Moon, we compiled multiple datasets to measure the concentrations of 13 different chemical compounds including calcium, iron oxide, titanium dioxide, and thorium. We then conducted a two-tailed T-test of the data, which generated probability values for the mean differences across all 13 chemical compounds of the maria sites with skylights and the maria sites without skylights. Our results show that there is no statistical difference in chemical composition across all of the maria sites examined. Therefore, we conclude that chemical composition does not predict or indicate potential skylight locations on the moon. Further research on other skylight characteristics, for example depth and surrounding underground lava channels, may shed light on the relationships between mare and skylights locations. Three Skylight Locations Found on Lunar Surface 100m View of Mare Tranquilitatis Skylight

Wong, J.; Torres, J.; FitzHoward, S.; Luu, E.; Hua, J.; Irby, R.

2013-12-01

14

Aerogel composites using chemical vapor infiltration  

Microsoft Academic Search

A new method to produce novel composite materials based on the use of aerogels as a starting material is described. Using chemical vapor infiltration, a variety of solid materials were thermally deposited into the open pore structure of aerogel. The resulting materials possess new and unusual properties including photoluminescence, magnetism and altered optical properties. An important characteristic of this preparation

Arlon J. Hunt; Michael R. Ayers; Wanqing Cao

1995-01-01

15

Chemical composition and morphology of renal stones.  

PubMed

Two issues related to nephrolithiasis are explored: (1) does the chemical composition and morphology of renal calculi in South Poland overlap with the studies from other countries? and (2) are there possibilities to evaluate in vivo chemical composition of stones using computed tomography? The study was conducted on 108 renal stones. X-ray fluorescence, X-ray diffraction and Fourier transformed infrared spectroscopy were used to determine the chemical composition. The morphology of the stones was examined using micro computed tomography. The stone chemical composition in South Poland indicate that calcium oxalate monohydrate was overwhelmingly dominant (84%) followed by hydroxyapatite (8%) and struvite (6%). The occurrence of uric acid stones was very low (2%). The relative frequency of various stone types is similar in South Poland to other industrialized countries. The studied renal stones were characterized by a large variability in the concentrations of both major and trace elements. The maximum/minimum concentration ratio exceeds two orders of magnitude. Significant morphological differences have been observed between different types of stones. The stones were composed of oxalate polyhedrons stuck together or had the phosphate core overlaid with layers oxalate and organic mater. The use of CT to identify stone type seems to be limited. PMID:24858554

Wrobel, Andrzej; Rokita, Eugeniusz; Taton, Grzegorz; Thor, Piotr

2013-01-01

16

Chemical composition of Luna 16 lunar regolith  

NASA Technical Reports Server (NTRS)

Data on the chemical composition of regolith returned by the Luna 16 automatic station and two fragments of basalts from the lower layer of the core are presented. Spark mass spectrometric, primary X-ray spectral, emission spectral, and atomic absorption methods were used in the analysis. The regolith of mare provinces were shown to be a mixture of material of various origins. The source of the material of the mare regolith was principally basalts of the corresponding lunar lava maria. The regolith is genetically related to it. This follows from a comparison of the chemical composition, mineralogical, and petrochemical features of the basesalts and the regolith from the Sea of Fertility, Sea of Tranquillity, and Ocean of Storms, respectively.

Vinogradov, A. P.; Chupakhin, M. S.; Belyayev, Y. I.

1974-01-01

17

Chemical Softening and Wear of Dental Composites  

Microsoft Academic Search

The purpose of this work was to determine the influence of chemical food-simulating liquids on the wear of various commercial dental composite restoratives. In many cases, pre-conditioning the restoratives in these liquids for one week produced swelling of the polymer matrix and considerable surface damage. The resulting degradation reduced the hardness and enhanced the wear as measured by a pin-and-disc

J. E. McKinney; W. Wu

1985-01-01

18

Chemical composition of the atmosphere of Venus  

NASA Astrophysics Data System (ADS)

The chemical composition of the subcloud atmosphere of Venus is studied in terms of thermochemical equilibrium calculations, comparison of typical mixing and chemical times, along with a rule governing the height-independent element mixing ratio in the absence of condensation. Calculations were made of the atmospheric photochemistry down to a height of 50 km, using transport effects and the number densities of CO2, H2O, HCl, SO2, and CO at the lower boundary; along with the rate coefficients of 102 reactions that include the catalytic cycles of COCl and COCl2 which accelerate O2 destruction and CO2 formation. Calculations show that sulfuric acid and sulfates are the second and third modes of particle size distribution in the middle and upper cloud layers, with the lower cloud layer perhaps consisting of AlCl3 and FeCl3.

Krasnopolsky, V. A.; Parshev, V. A.

1981-08-01

19

The chemical composition of AGN outflows  

NASA Astrophysics Data System (ADS)

We propose a simultaneous Chandra LETGS - HST/COS observation of the bright Seyfert 1 galaxy Mrk 509, within half a year from an approved large XMM-Newton monitoring campaign. Combining 180 ks LETGS time and 10 orbits of COS time with the XMM-Newton RGS spectrum, we will obtain accurate abundances of C, N, O, Ne, Si, S, and Fe over a broad range of ionisation parameter. This allows us to determine directly the contributions from various supernova types and intermediate mass stars to the chemical enrichment processes in galaxy cores. It also will reveal directly the chemical composition of the outflow that enriches the surrounding diffuse medium. Our team has succesfully executed a similar abundances campaign on Mrk 279.

Kaastra, Jelle

2009-09-01

20

The chemical composition of AGN outflows  

NASA Astrophysics Data System (ADS)

We propose a simultaneous Chandra LETGS - HST/COS observation of the bright Seyfert 1 galaxy Mrk 509, within half a year from an approved large XMM-Newton monitoring campaign. Combining 180 ks LETGS time and 10 orbits of COS time with the XMM-Newton RGS spectrum, we will obtain accurate abundances of C, N, O, Ne, Si, S, and Fe over a broad range of ionisation parameter. This allows us to determine directly the contributions from various supernova types and intermediate mass stars to the chemical enrichment processes in galaxy cores. Italso will reveal directly the chemical composition of the outflow that enriches the surrounding diffuse medium. Our team has succesfully executed a similar abundances campaign on Mrk 279.;

Kaastra, Jelle

2008-07-01

21

Chemical composition of composted grape marc.  

PubMed

Composted grape marc, produced at the vineyard using different procedures, is generally returned into the vineyard. Information on the chemical composition of these grape marc composts is lacking, particularly the variability that may result from different composting practices. In this study, grape marc composts, varying in age from 3 months to 3 years, were collected from four different vineyards and subjected to detailed chemical analysis. The chemical analysis revealed that all the grape marc composts contained levels of free potassium, in the range of 2-3% w/w. Plant macronutrients such as Ca, S, Mg were present at low levels (<1% w/w), while phosphorus (0.1-0.3% w/w) and nitrogen (1-2% w/w) levels were not very high and mainly present in "plant unavailable" form. The levels of soluble salts, though not excessive, were elevated in all the composts. These salt levels could cause a problem in some soils. Heavy metals were not present in any significant levels. All the grape marc composts analysed provided some benefit in returning nutrients into the vineyard and all were significant potassium sources. PMID:19717914

Patti, Antonio F; Issa, G Jason; Smernik, Ron; Wilkinson, Kevin

2009-01-01

22

Chemical composition of Texas surface waters, 1949  

USGS Publications Warehouse

This report is the fifth the a series of publications by the Texas Board of Water Engineers giving chemical analyses of the surface waters in the State of Texas. The samples for which data are given were collected between October 1, 1948 and September 30, 1949. During the water year 25 daily sampling stations were maintained by the Geological Survey. Sampled were collected less frequently during the year at many other points. Quality of water records for previous years can be found in the following reports: "Chemical Composition of Texas Surface Waters, 1938-1945," by W. W. Hastings, and J. H. Rowley; "Chemical Composition of Texas Surface Waters, 1946," by W. W. Hastings and B. Irelan; "Chemical Composition of Texas Surface Waters, 1947," by B. Irelan and J. R. Avrett; "Chemical Composition of Texas Surface Waters, 1948," by B. Irelan, D. E. Weaver, and J. R. Avrett. These reports may be obtained from the Texas Board of Water Engineers and Geological Survey at Austin, Texas. Samples for chemical analysis were collected daily at or near points on streams where gaging stations are maintained for measurement of discharge. Most of the analyses were made of 10-day composites of daily samples collected for a year at each sampling point. Three composite samples were usually prepared each month by mixing together equal quantities of daily samples collected for the 1st to the 10th, from the 11th to the 20th, and during the remainder of the month. Monthly composites were made at a few stations where variation in daily conductance was small. For some streams that are subject to sudden large changes in chemical composition, composite samples were made for shorter periods on the basis of the concentration of dissolved solids as indicated by measurement of specific conductance of the daily samples. The mean discharge for the composite period is reported in second-feet. Specific conductance values are expressed as "micromhos, K x 10 at 25° C." Silica, calcium, magnesium, sodium, potassium, bicarbonate, sulfate, chloride, and nitrate are reported in parts per million. The quantity of dissolved solids is given in tons per acre-foot, tons per day (if discharge records are available), and parts per million. The total and non-carbonate hardness are reported as parts per million calcium carbonate (CaCO3). For those analyses where sodium and potassium are reported separately, "recent sodium" will include the equivalent quantity of sodium only. In analyses where sodium and potassium were calculated and reported as a combined value, the "percent sodium" will include the equivalent quantity of sodium and potassium. Weighted average analyses are given for most daily sampling stations. The weighted average analysis represent approximately the composition of water that would be found in a reservoir containing all the water passing a given station during the year after through mixing in the reservoir. Samples were analyzed according to method regularly used by the Geological Survey. These methods are essentially the same or are modifications of methods described in recognized authoritative publications for mineral analysis of water samples. These quality of water records have been collected as part of the cooperative investigations of the water resources of Texas conducted by the Geological Survey and the Texas Board of Water Engineers. Much of the work would have been impossible without the support of the following Federal State, and local agencies The United States Bureau of Reclamation, U. S. Corps of Engineers, Brazos River Conservation and Reclamation District, Lower Colorado River Authority, Red Bluff Water Power Control District, City of Amarillo, City of Abilene, and City of Forth Worth. The investigations were under the firection of Burdge Irelan, District Chemist, Austin, Texas. Analyses of water samples were made by Clara J. Carter, Lee J. Freeman, Homer D. Smith, Dorothy M. Suttle, DeForrest E. Weaver, and Clarence T. Welborn. Calculations of weighted averages were made by James R. Avrett, Burdge Irelan, Dorothy M. Suttle, and DeFor

Irelan, Burdge

1950-01-01

23

Chemical softening and wear of dental composites.  

PubMed

The purpose of this work was to determine the influence of chemical food-simulating liquids on the wear of various commercial dental composite restoratives. In many cases, pre-conditioning the restoratives in these liquids for one week produced swelling of the polymer matrix and considerable surface damage. The resulting degradation reduced the hardness and enhanced the wear as measured by a pin-and-disc apparatus. Four kinds of commercial composites were investigated: a conventional quartz-filled, a strontium-glass-filled, a visible-light-activated, and a microfilled composite. The liquids employed were heptane and several aqueous solutions of ethanol with solubility parameters, delta, ranging from delta = 1.5 to 4.8 X 10(4) J1/2m-3/2. With all restoratives, the decline in hardness during pre-conditioning maximized at about delta = 3 X 10(4), which corresponds to a 75% ethanol solution. The wear behavior was considerably more complicated and variable, as discussed in the text. For the most part, the increase in wear rate from pre-conditioning corresponded to the fall in hardness. A notable exception was for the strontium-glass-filled composite pre-conditioned in pure water. Here the wear was enhanced considerably, with no decrease in hardness. In this case, the degradation mode is assumed to be different from the others in that it is attributed to stress corrosion of the glass filler. PMID:2936780

McKinney, J E; Wu, W

1985-11-01

24

Establishing of chemical composition of printing ink.  

PubMed

The subject of the examinations was primarily court tax marks of 50 and 200 PLN, which were suspected not to be genuine. Both inks on the questioned marks as well as comparative genuine marks and inks sent by the manufacturer were analyzed. No information about their chemical composition was available from manufacturer. In the examinations, infrared (IR), visible, X-ray fluorescence, and Raman spectrometry were used. The examinations showed that inks and glue on the marks of both values were the same as samples of those sent by the manufacturer. Discrepancies in some results were observed probably due to contamination, that is, an accidental presence of the foreign substance on the surface (e.g., sweat, saliva while sticking the marks to the surface or physical handling of the documents). It was concluded that there are original (genuine) court tax marks. PMID:21361954

Zi?ba-Palus, Janina; Trzci?ska, Beata M

2011-05-01

25

Chemical composition of distillers grains, a review.  

PubMed

In recent years, increasing demand for ethanol as a fuel additive and decreasing dependency on fossil fuels have resulted in a dramatic increase in the amount of grains used for ethanol production. Dry-grind is the major process, resulting in distillers dried grains with solubles (DDGS) as a major coproduct. Like fuel ethanol, DDGS has quickly become a global commodity. However, high compositional variation has been the main problem hindering its use as a feed ingredient. This review provides updated information on the chemical composition of distillers grains in terms of nutrient levels, changes during dry-grind processing, and causes for large variation. The occurrence in grain feedstock and the fate of mycotoxins during processing are also covered. During processing, starch is converted to glucose and then to ethanol and carbon dioxide. Most other components are relatively unchanged but concentrated in DDGS about 3-fold over the original feedstock. Mycotoxins, if present in the original feedstock, are also concentrated. Higher fold of increases in S, Na, and Ca are mostly due to exogenous addition during processing, whereas unusual changes in inorganic phosphorus (P) and phytate P indicate phytate hydrolysis by yeast phytase. Fermentation causes major changes, but other processing steps are also responsible. The causes for varying DDGS composition are multiple, including differences in feedstock species and composition, process methods and parameters, the amount of condensed solubles added to distiller wet grains, the effect of fermentation yeast, and analytical methodology. Most of them can be attributed to the complexity of the dry-grind process itself. It is hoped that information provided in this review will improve the understanding of the dry-grind process and aid in the development of strategies to control the compositional variation in DDGS. PMID:21299215

Liu, KeShun

2011-03-01

26

Carbon Nano Tube Composites with Chemically Functionalized Plant Oils  

Microsoft Academic Search

Carbon Nano Tube Composites with Chemically Functionalized Plant Oil Wim Thielemans, R., P. Wool, V. Barron and W. Blau Multi-Wall Carbon Nano Tubes (MWCNT) made by the Kratchmer-Huffman CCVD process were found to interact and solubilize by slow mechanical stirring, with chemically functionalized plant oils, such as acrylated, epoxidized and maleinated triglycerides (TG) derived from plant oils. The chemical functionality

Wim Thielemans; Richard P. Wool; Werner Blau; Valerie Barron

2003-01-01

27

Chemical composition of Desulfovibrio desulfuricans lipid A  

PubMed Central

Lipopolysaccharides also called endotoxins are an integral component of the outer membrane of Gram-negative bacteria. When released from the bacterial surface, they interact with a host immune system, triggering excessive inflammatory response. Lipid A is the biologically most active part of endotoxin, and its activity is modulated by the quantity, quality and arrangement of its fatty acids. Desulfovibrio desulfuricans is sulfate-reducing, Gram-negative bacterium that is supposed to be opportunistic pathogens of humans and animals. In the present study, chemical composition of lipid A from various strains of D. desulfuricans was analyzed by gas chromatography/mass spectrometry. It was found that the fatty acid component of the lipid A contains dodecanoic, tetradecanoic, 3-hydroxytetradecanoic and hexadecanoic acids, and its carbohydrate core is composed of glucosamine. The analysis of 3-acyloxyacyl residue of the lipid A revealed the presence of amide-bound 3-(dodecanoyloxy)tetradecanoic and 3-(hexadecanoyloxy)tetradecanoic acids and ester-bound 3-(tetradecanoyloxy)tetradecanoic acid. It was concluded that both fatty acid and 3-acyloxyacyl residue profiles of the lipid A from the studied bacteria were similar to those of E. coli and S.enterica.

Lodowska, Jolanta; Jaworska-Kik, Marzena; Kurkiewicz, Slawomir; Weglarz, Ludmila; Dzierzewicz, Zofia

2010-01-01

28

Fundamental Parameters and Chemical Composition of Arcturus  

NASA Astrophysics Data System (ADS)

We derive a self-consistent set of atmospheric parameters and abundances of 17 elements for the red giant star Arcturus: T eff = 4286 ± 30 K, log g = 1.66 ± 0.05, and [Fe/H] = -0.52 ± 0.04. The effective temperature was determined using model atmosphere fits to the observed spectral energy distribution from the blue to the mid-infrared (0.44 to 10 ?m). The surface gravity was calculated using the trigonometric parallax of the star and stellar evolution models. A differential abundance analysis relative to the solar spectrum allowed us to derive iron abundances from equivalent width measurements of 37 Fe I and 9 Fe II lines, unblended in the spectra of both Arcturus and the Sun; the [Fe/H] value adopted is derived from Fe I lines. We also determine the mass, radius, and age of Arcturus: M = 1.08 ± 0.06 M ?, R = 25.4 ± 0.2 R ?, and ? = 7.1+1.5 - 1.2 Gyr. Finally, abundances of the following elements are measured from an equivalent width analysis of atomic features: C, O, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, and Zn. We find the chemical composition of Arcturus typical of that of a local thick-disk star, consistent with its kinematics.

Ramírez, I.; Allende Prieto, C.

2011-12-01

29

Chemical composition and size distributions for fly ashes  

Microsoft Academic Search

Inter-particle variations in particle diameter and chemical composition in coal fly ashes are significant, and can be quantitatively studied using currently available microanalytical techniques. One such technique, computer controlled scanning electron microscopy (CCSEM), is now routinely used to determine chemical compositions and diameters of individual fly ash particles, using statistically significant sample sizes. This paper proposes simple mathematical formulae for

Sarbajit Ghosal; Jon L. Ebert; Sidney A. Self

1995-01-01

30

On line chemical composition of analyzer development  

SciTech Connect

This status report details progress made on the development of an on-line chemical analyzer. Dynamic studies of the distillation column, approval of testing plans, installation of a sample cell and raman analyzer, design of computerized control systems are described. Information on seminars and published papers is also included. (GHH)

Not Available

1992-01-01

31

Propolis chemical composition and honeybee resistance against Varroa destructor.  

PubMed

Propolis is known as honeybee chemical defence against infections and parasites. Its chemical composition is variable and depends on the specificity of the local flora. However, there are no data concerning the relationship between propolis chemical composition and honeybee colony health. We tried to answer this question, studying the chemical composition of propolis of bee colonies from an apiary near Avignon, which are tolerant to Varroa destructor, comparing it with colonies from the same apiary which are non-tolerant to the mites. The results indicated that non-tolerant colonies collected more resin than the tolerant ones. The percentage of four biologically active compounds - caffeic acid and pentenyl caffeates - was higher in propolis from tolerant colonies. The results of this study pave the way to understanding the effect of propolis in individual and social immunity of the honeybees. Further studies are needed to clarify the relationship between propolis chemical composition and honeybee colony health. PMID:24483289

Popova, M; Reyes, M; Le Conte, Y; Bankova, V

2014-06-01

32

Hanford defined wastes: Chemical and radionuclide compositions  

SciTech Connect

This report is a key part of a three part strategy for estimating the contents of the waste tanks at Hanford. Chemical inventories are estimated based on overall chemicals used in a process versus the actual waste that the process produced, and flowsheet information is used to tie various species together. Using this concentration of input chemicals, each ion is precipitated until it reaches a solubility limit. This solubility limit is typical for that ion as derived from analytical data for supernatant from Hanford waste tanks that have been reported over the years. The solids that precipitate are packed according to a solids volume per cent that is also typical for the type of waste in the Hanford waste tanks. Radionuclides estimated in this report are restricted to plutonium, uranium, thorium, cesium-137, and strontium-90. Total amounts produced are estimated based on tons of fuel processed versus an average exposure rate for the fuel in MWD/Ton. Once the total amounts of Pu, U and Th are estimated, the residual amounts within the wasted are calculated based on process efficiencies. Waste concentrates are estimated based on one of nine evaporator campaigns. Each evaporator campaign involved a supernatant feed volume averaged for the entire campaign and a waste reduction factor, producing saltcake precipitate and supernatant.

Agnew, S.F. [Los Alamos National Lab., NM (United States)

1995-09-01

33

Seasonal Changes in the Chemical Composition of Commingled Goat Milk  

Microsoft Academic Search

Production of goat milk cheese in North America has been growing rapidly during the past several years. However, information on chemical composition and its seasonal varia- tion of year-round bulk-collected goat milk is limited. The objective of this study was to analyze the chemical composi- tion of commercial goat milk shipments for an entire year to provide fundamental information for

Ming R. Guo; Peter H. Dixon; Young W. Park; James A. Gilmore; Paul S. Kindstedt

2001-01-01

34

Composition and Structure of Chemically Deposited PbS.  

National Technical Information Service (NTIS)

In a study of the fundamental properties of chemically deposited lead sulfide, new instrumental techniques-scanning electron microscopy (SEM) and mass spectroscopy--were applied to the analysis of structure and composition. Lead sulfide samples were prepa...

M. H. Ritchie C. M. Drew

1969-01-01

35

The Chemical Composition of Praesepe (M44)  

NASA Astrophysics Data System (ADS)

Star clusters have long been used to illuminate both stellar evolution and Galactic evolution. They also hold clues to the chemical and nucleosynthetic processes throughout the history of the Galaxy. We have taken high signal-to-noise (S/N), high-resolution spectra of 11 solar-type stars in the Praesepe open cluster to determine the chemical abundances of 16 elements: Li, C, O, Na, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Fe, Ni, Y, and Ba. We have determined Fe from Fe I and Fe II lines and find [Fe/H] = +0.12 ±0.04. We find that Li decreases with temperature due to increasing Li depletion in cooler stars; it matches the Li-temperature pattern found in the Hyades. The [C/Fe] and [O/Fe] abundances are below solar and lower than the field star samples due to the younger age of Praesepe (0.7 Gyr) than the field stars. The alpha-elements, Mg, Si, Ca, and Ti, have solar ratios with respect to Fe, and are also lower than the field star samples. The Fe-peak elements, Cr and Ni, track Fe and have solar values. The neutron capture element [Y/Fe] is found to be solar, but [Ba/Fe] is enhanced relative to solar and to the field stars. Three Praesepe giants were studied by Carrera and Pancino; they are apparently enhanced in Na, Mg, and Ba relative to the Praesepe dwarfs. The Na enhancement may indicate proton-capture nucleosynthesis in the Ne ? Na cycling with dredge-up into the atmospheres of the red giants.

Boesgaard, Ann Merchant; Roper, Brian W.; Lum, Michael G.

2013-09-01

36

"Chemical" composition of the Quark Gluon Plasma  

NASA Astrophysics Data System (ADS)

In this article we discuss the issue of the quark to gluon ratio in the Quark Gluon Plasma (QGP). Our model to describe the QGP evolution is based on transport theory including the mean field dynamics described by a quasi-particle model.The last is able to take into account for the lattice QCD thermodynamics and implies a "chemical" equilibrium ratio between quarks and gluons strongly increasing as T approaches to the temperature of the phase transition Tc. We present first the tests performed in a fixed box to check that our code is able to reproduce the equilibrium ratio and then the results obtained for the simulations of ultra-Relativistic Heavy Ion Collisions (uRHIC's) at RHIC and LHC energies. We observe a rapid evolution from a gluon dominated initial state to a quark dominated plasma and we see that near Tc almost 80% of the particles composing the plasma are quarks. This has potentially a strong impact on several quantitative aspects of QGP probes and furnishes a justification to the coalescence hadronization model.

Scardina, Francesco; Colonna, Maria; Plumari, Salvatore; Greco, Vincenzo

2013-09-01

37

Chemical and anatomical compositions of coal precursors  

SciTech Connect

Four cores of peat from various environments in the Florida Everglades and one from the Okefenokee Swamp, Georgia have been studied with the objective of clarifying the roles of cellulose, lignin and other vascular plant polymers as input to coalification. The peat was first separated by set sieving into a coarse fraction consisting of fragments of plant organs and tissues, and a fine fraction containing an amorphous humic matrix mixed with a minority of disrupted cellular material. Microscopic examination, Curie-point pyrolysis/mass spectrometry with multivariate statistical analyses of the data, supplemented by pyrolysis/gas chromatography and PY/GC/MD, revealed substantial differences in the degree of preservation of plant tissues and in chemistry between peats derived from different types of plants. Some ..cap alpha..-cellulose is present in the upper levels of the peats, but the total polysaccharide content decreases markedly with depth, perhaps due in some cases to changes in the source vegetation, but mainly due to selective enzymatic removal of certain monomer units from polymeric lignin, thereby concentrating the structural types remaining (notably structures related to p.coumaryl alcohol). Polymeric aliphatic hydrocarbon structures are present in nearly all samples, but are more abundant at the lower depths. The chemical and morphological differences in peats are likely to be reflected in the coals that may form from them.

Ryan, N.J.

1985-01-01

38

Chemical composition and protein quality of buckwheat ( Fagopyrum esculentum Moench )  

Microsoft Academic Search

The chemical composition and protein quality of two varieties of buckwheat were measured and compared with the values of wheat. The protein quality was based on amino acid composition and true protein digestibility, biological value, net protein utilization, and utilizable protein obtained in N-balance experiments with rats. The protein content in buckwheat was approximately 12% and thus very much the

Bjørn O. Eggum; Ivan Kreft; Branka Javornik

1980-01-01

39

Cometary coma chemical composition (C4) mission. [Abstract only  

NASA Technical Reports Server (NTRS)

Cometary missions are of enormous fundamental importance for many different space science disciplines, including exobiology. Comets are presumed relics of the earliest, most primitive material in the solar nebula and are related to the planetesimals. They undoubtedly provided a general enrichment of volatiles to the inner solar system (contributing to atmospheres and oceans) and may have been key to the origin of life. A Discovery class, comet rendezvous mission, the Cometary Coma Chemical Composition (C4) Mission, was selected for further study by NASA earlier this year. The C4 Mission is a highly focused and usefully-limited subset of the Cometary Rendezvous Asteroid Flyby (CRAF) Mission, concentrating exclusively on measurements which will lead to an understanding of the chemical composition and make-up of the cometary nucleus. The scientific goals of the Cometary Coma Chemical Composition (C4) Mission are to rendezvous with a short-period comet and (1) to determine the elemental, chemical, and isotopic composition of the nucleus and (2) to characterize the chemical and isotopic nature of its atmosphere. Further, it is a goal to obtain preliminary data on the development of the coma (dust and gas composition) as a function of time and orbital position.

Carle, G. C.; Clark, B. C.; Niemann, H. B.; Alexander, M.; Knocke, P. C.; O'Hara, B. J.

1994-01-01

40

Studies on the chemical composition and physico-chemical properties of seeds of some wild plants  

Microsoft Academic Search

The Seeds of the fruits of some wild plants were analysed to establish their proximate compositions and the physico-chemical characteristics of the oils. The iodine values of the oils were not greater than 88 but the saponification values were in the range 157–261 mg KOH. Proximate values of the protein, oil and carbohydrate contents of the seeds suggest that they

Ighodalo C. Eromosele; Catherine O. Eromosele

1993-01-01

41

Biofuels from waste fish oil pyrolysis: Chemical composition  

Microsoft Academic Search

In a previous study, waste fish oil was converted into bio-oil by a fast pyrolysis process at 525°C in a continuous pilot plant reactor with 72–73% yield. The bio-oil was distilled to obtain light bio-oil and heavy bio-oil and these biofuels were characterized in terms of their physico-chemical properties. In this study, the chemical composition of light bio-oil and heavy

A. Wisniewski Jr.; V. R. Wiggers; E. L. Simionatto; H. F. Meier; A. A. C. Barros; L. A. S. Madureira

2010-01-01

42

Chemical composition of Cynara scolymus leaves  

Microsoft Academic Search

methionine. The amino-acid composition was studied in further detail as before [3]. The qualitative composition of amino acids was determined from retention times. The internal standard was a standard mixture of 18 amino acids. Colored complexes that were formed by reaction with ninhydrin were measured colorimetrically at 570 nm. Peak areas of identified acids were used for quantitative determination (automatically).

T. V. Orlovskaya; I. L. Luneva; V. A. Chelombit’ko

2007-01-01

43

Fuel options from microalgae with representative chemical compositions  

SciTech Connect

Representative species of microalgae are examined with respect to their reported chemical compositions. Each species is analyzed under a variety of culture conditions, with the objective being to characterize an optimum mixture of fuel products (e.g., methane, ethanol, methylester) which should be produced by the particular species. Historically the emphasis has been on the entire algal cell mass. Using the reported chemical composition for the representative species under specific sets of growth conditions, some conclusions can be drawn about the preferred fuel product conversion routes that could be employed. 10 references, 7 figures, 12 tables.

Feinberg, D. A.

1984-07-01

44

Cyanobacterial chemical warfare affects zooplankton community composition  

Microsoft Academic Search

SUMMARY 1. Toxic algal blooms widely affect our use of water resources both with respect to drinking water and recreation. However, it is not only humans, but also organisms living in freshwater and marine ecosystems that may be affected by algal toxins. 2. In order to assess if cyanobacterial toxins affect the composition of natural zooplankton communities, we quantified the

LARS-ANDERS HANSSON; SUSANNE GUSTAFSSON; KARIN RENGEFORS; LINA BOMARK

2007-01-01

45

Chemical composition of Earth, Venus, and Mercury  

PubMed Central

Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of available data shows only a few gross trends for the inner planets: FeO decreases with heliocentric distance, whereas volatiles are depleted and refractories are enriched in the smaller planets. Images

Morgan, John W.; Anders, Edward

1980-01-01

46

Chemical constraints on fly ash glass compositions  

SciTech Connect

The major oxide content and mineralogy of 75 European fly ashes were examined, and the major element composition of the glass phase was obtained for each. Correlation of compositional trends with the glass content of the ash was explored. Alkali content was deduced to have a major influence on glass formation, and this in turn could be related to the probable chemistry of clay minerals in the source coals. Maximal glass content corresponded to high aluminum content in the glass, and this is in accordance with the theoretical mechanism of formation of aluminosilicate glasses, in which network-modifying oxides are required to promote tetrahedral coordination of aluminum in glass chain structures. Iron oxide was found to substitute for alkali oxides where the latter were deficient, and some indications of preferred eutectic compositions were found. The work suggests that the proportion of the glass phase in the ash can be predicted from the coal mineralogy and that the utility of a given ash for processing into geopolymers or zeolites is determined by its source. 23 refs., 7 figs., 1 tab.

John H. Brindle; Michael J. McCarthy [University of Dundee, Dundee (United Kingdom). Division of Civil Engineering

2006-12-15

47

Chemical Composition of Icy Satellite Surfaces  

NASA Astrophysics Data System (ADS)

Much of our knowledge of planetary surface composition is derived from remote sensing over the ultraviolet through infrared wavelength ranges. Telescopic observations and, in the past few decades, spacecraft mission observations have led to the discovery of many surface materials, from rock-forming minerals to water ice to exotic volatiles and organic compounds. Identifying surface materials and mapping their distributions allows us to constrain interior processes such as cryovolcanism and aqueous geochemistry. The recent progress in understanding of icy satellite surface composition has been aided by the evolving capabilities of spacecraft missions, advances in detector technology, and laboratory studies of candidate surface compounds. Pioneers 10 and 11, Voyagers I and II, Galileo, Cassini and the New Horizons mission have all made significant contributions. Dalton (Space Sci. Rev., 2010, this issue) summarizes the major constituents found or inferred to exist on the surfaces of the icy satellites (cf. Table 1 from Dalton, Space Sci. Rev., 2010, this issue), and the spectral coverage and resolution of many of the spacecraft instruments that have revolutionized our understanding (cf. Table 2 from Dalton, Space Sci. Rev., 2010, this issue). While much has been gained from these missions, telescopic observations also continue to provide important constraints on surface compositions, especially for those bodies that have not yet been visited by spacecraft, such as Kuiper Belt Objects (KBOs), trans-Neptunian Objects (TNOs), Centaurs, the classical planet Pluto and its moon, Charon. In this chapter, we will discuss the major satellites of the outer solar system, the materials believed to make up their surfaces, and the history of some of these discoveries. Formation scenarios and subsequent evolution will be described, with particular attention to the processes that drive surface chemistry and exchange with interiors. Major similarities and differences between the satellites are discussed, with an eye toward elucidating processes operating throughout the outer solar system. Finally we discuss the outermost satellites and other bodies, and summarize knowledge of their composition. Much of this review is likely to change in the near future with ongoing and planned outer planet missions, adding to the sense of excitement and discovery associated with our exploration of our planetary neighborhood.

Dalton, J. B.; Cruikshank, D. P.; Stephan, K.; McCord, T. B.; Coustenis, A.; Carlson, R. W.; Coradini, A.

2010-06-01

48

Chemical composition of Hanford Tank SY-102  

SciTech Connect

The US Department of Energy established the Tank Waste Remediation System (TWRS) to safely manage and dispose of the radioactive waste, both current and future, stored in double-shell and single-shell tanks at the Hanford sites. One major program element in TWRS is pretreatment which was established to process the waste prior to disposal using the Hanford Waste Vitrification Plant. In support of this program, Los Alamos National Laboratory has developed a conceptual process flow sheet which will remediate the entire contents of a selected double-shelled underground waste tank, including supernatant and sludge, into forms that allow storage and final disposal in a safe, cost-effective and environmentally sound manner. The specific tank selected for remediation is 241-SY-102 located in the 200 West Area. As part of the flow sheet development effort, the composition of the tank was defined and documented. This database was built by examining the history of liquid waste transfers to the tank and by performing careful analysis of all of the analytical data that have been gathered during the tank`s lifetime. In order to more completely understand the variances in analytical results, material and charge balances were done to help define the chemistry of the various components in the tank. This methodology of defining the tank composition and the final results are documented in this report.

Birnbaum, E.; Agnew, S.; Jarvinen, G.; Yarbro, S.

1993-12-01

49

Chemical imaging of wood-polypropylene composites.  

PubMed

Recent investigations of wood plastic composites have revealed a detrimental effect of using lubricant systems in production. This includes nullifying part or all of the mechanical benefit of using a polar compatibilizer, maleic anhydride polypropylene (MAPP), in the composite formulation. This investigation utilizes lubricants labeled with deuterium in conjunction with Fourier transform infrared (FT-IR) spectroscopy to allow for the separation of individual lubricants from all other material constituents. All of the deuterium labeled lubricants, used without MAPP, revealed their expulsion from the wood interface during crystallization. MAPP coupling agent was found to exist near the wood, but it is unclear if any covalent bonding with the hydroxyl functionality on the wood surface occurred. The addition of zinc stearate lubricants appears to nullify the activity of the anhydride functionality near the wood surface as evidenced by a shift in the FT-IR spectra to the hydrolyzed form of the coupling agent. Most of the additives collect at the edges of the spherulites in mostly amorphous regions of the material. The consequence of this morphology may be a weak interface between crystallites. PMID:16925926

Harper, David P; Wolcott, Michael P

2006-08-01

50

Physical and chemical composition of hospital waste.  

PubMed

For selecting the most efficient treatment method of hospital waste, the composition analysis is generally considered to be the fundamental information. Currently, there are few studies regarding the characteristics of hospital waste. This study evaluated the physical and elemental composition of the hospital waste at the National Taiwan University Hospital (NTUH). The results should help us design an incinerator for the treatment of infectious waste, plastic syringes, pathological waste, and kitchen waste. During the study period, the estimated daily waste generation rate at NTUH was 4,600 kg/day, which consisted of 4,100 kg/day noninfectious refuse, 340 kg/day infectious waste, 70 kg/day kitchen waste, 50 kg/day pathological waste, and 40 kg/day plastic syringes. The NTUH waste consisted of 99.02% combustible wastes and 0.97% noncombustible wastes by mass. The combustible wastes constituted paper (16.17%), textiles (9.77%), cardboard, wood, and leaves (1.12%), food waste (21.51%), and plastics (50.45%). The noncombustible waste included 0.40% metal and 0.57% glass. Furthermore, the analysis indicated that the wastes contained 38% moisture, 4% ashes, and 58% solid with an average heat value of 3,400 kcal/kg. From the elemental analysis, the dominant elements were found to be carbon (34%) and oxygen (15%). PMID:8478527

Li, C S; Jenq, F T

1993-03-01

51

Energetic composites and method of providing chemical energy  

DOEpatents

A method for providing chemical energy and energetic compositions of matter consisting of thin layers of substances which will exothermically react with one another. The layers of reactive substances are separated by thin layers of a buffer material which prevents the reactions from taking place until the desired time. The reactions are triggered by an external agent, such as mechanical stress or an electric spark. The compositions are known as metastable interstitial composites (MICs). This class of compositions includes materials which have not previously been capable of use as energetic materials. The speed and products of the reactions can be varied to suit the application.

Danen, Wayne C. (Los Alamos, NM) [Los Alamos, NM; Martin, Joe A. (Espanola, NM) [Espanola, NM

1997-01-01

52

Chemical composition of sewage-grown Spirulina platensis  

Microsoft Academic Search

Summary Spirulina platensis has been grown in an outdoor pilot production unit, with an exposed surface area of 450 m2, on a medium consisting of raw domestic sewage supplemented with sodium bicarbonate and nitrate or urea fertilizer. The chemical composition and yield of the biomass grown on sewage-nitrate was comparable to that grown on synthetic medium. The protein content was

P. N. Saxena; M. R. Ahmad; R. Shyam; P. S. Misra

1982-01-01

53

Chemical composition of native and anodic oxides on indium antimonide  

SciTech Connect

The authors investigate the chemical composition, growth kinetics, and properties of anodic and native oxides on the surface of a semiconductor such as indium antimonide, which is important from the practical point of view. The native oxide is obtained as a result of the interaction of the semiconductor surface with oxygen in some gaseous medium.

Gnedenkov, S.V.; Gordineko, P.S.; Kandinskii, M.P.; Mischenko, N.M.; She venko, V.Y.; Zelenskii, Y.V.

1985-10-01

54

Optimum conditions for composites fiber coating by chemical vapor infiltration  

Microsoft Academic Search

A combined analytical and numerical method is employed to optimize process conditions for composites fiber coating by chemical vapor infiltration. For a first-order deposition reaction, the optimum pressure yielding the maximum deposition rate at a preform center is obtained in closed form and is found to depend only on the activation energy of the deposition reaction, the characteristic pore size,

Stewart K. Griffiths; R. H. Nilson

1998-01-01

55

Computer program determines chemical composition of physical system at equilibrium  

NASA Technical Reports Server (NTRS)

FORTRAN 4 digital computer program calculates equilibrium composition of complex, multiphase chemical systems. This is a free energy minimization method with solution of the problem reduced to mathematical operations, without concern for the chemistry involved. Also certain thermodynamic properties are determined as byproducts of the main calculations.

Kwong, S. S.

1966-01-01

56

The Chemical Composition of Fogs and Clouds in Southern California  

Microsoft Academic Search

Fog and clouds are frequent occurrences in Southern California. Their chemical composition is of interest due to their potential role in the transformation of sulfur and nitrogen oxides to sulfuric and nitric acid and in the subsequent deposition of those acids. In addition, cloud and fog droplets may be involved in the chemistry of low-molecular-weight carboxylic acids and carbonyl compounds.

James William Munger

1989-01-01

57

Control of Chemical Composition of Nickel Superalloys for Microstructural Stability.  

National Technical Information Service (NTIS)

Specimens from laboratory melts of the nickel alloys IN 738 LC (ATS 385 DG), IN 597 and IN 939 with variations in chemical composition to obtain different structural stability were subjected to long duration annealing at 700 and 800 C, creep rupture tests...

F. Schubert

1979-01-01

58

Fruit chemical composition of hazelnut cultivars grown in Portugal  

Microsoft Academic Search

Chemical composition (crude protein, crude fat, starch, neutral detergent ? bre - NDF and free ?-amino acids) of six hazelnut cultivars (Butler, Ennis, Fertile de Coutard, Grossal, Merveille de Bollwiller and Segorbe) was investigated. Genotype signi? cantly affected fruit nutritive value. Crude protein ranged from 12-17 g 100 g -1 dry weight (dw) in cultivar Ennis and Merveille de Bollwiller,

A. P. Silva; A. Santos; J. Cavalheiro; C. Ribeiro; F. Santos; B. Gonçalves

59

Brazilian Propolis: Correlation between Chemical Composition and Antimicrobial Activity  

Microsoft Academic Search

The chemical composition of ethanol extracts from samples of Brazilian propolis (EEPs) determined by HPLC and their activity against Trypanosoma cruzi, Staphylococcus aureus, Streptococcus pneumoniae, Klebisiella pneumoniae, Candida albicans, Sporothrix schenckii and Paracoccidioides brasiliensis were determined. Based on the predominant botanical origin in the region of samples' collection, the 10 extracts were separated into three groups: A( B. dracunculifolia þ

Kelly Salomão; Paulo Roberto S. Pereira; Leila C. Campos; Cintia M. Borba; Pedro H. Cabello; Maria Cristina Marcucci; Solange L. de Castro

2008-01-01

60

The Chemical Composition of Some Mediterranean Citrus Oils  

Microsoft Academic Search

To compare the regional variations of the quantitative chemical composition, some Mediterranean citrus oils (lemon, sweet orange, bitter orange, and mandarin) from Italy and Spain have been studied. Over 100 constituents were identified in the various oils, from which 80 components could be quantified.No significant differences were found in the concentrations of the main constituents of sweet orange oils from

Mans H. Boelens; Rafael Jimenez

1989-01-01

61

Chemically treated fillers and polymeric compositions containing same  

US Patent & Trademark Office Database

Described are fillers, e.g., inorganic oxides, that have been chemically treated to have a carbon content of greater than 1 weight percent, a mercapto content of at least 0.15 weight percent, a Silane Conversion Index of at least 0.3 and a Standard Reinforcement Index of 4 or more. Polymeric compositions that contain such treated fillers are also described.

2003-11-18

62

Chemical vapor infiltration of non-oxide ceramic matrix composites  

SciTech Connect

Continuous fiber ceramic composites are enabling new, high temperature structural applications. Chemical vapor infiltration methods for producing these composites are being investigated, with the complexity of filament weaves and deposition chemistry merged with standard heat and mass transport relationships. Silicon carbide- based materials are, by far, the most mature, and are already being used in aerospace applications. This paper addresses the state-of-the-art of the technology and outlines current issues.

Besmann, T.M.; Stinton, D.P.; Lowden, R.A.

1993-12-31

63

Chemical Composition and Quality of Malaysian Fish Balls  

Microsoft Academic Search

Ten samples of Malaysian fish balls were analyzed for proximate composition (moisture, protein, fat, ash and carbohydrate), colour and texture. The results showed that the chemical composition and colour of each sample were significantly different (p<0.05). The moisture, protein, fat, ash and carbohydrate contents varies between 72.5 - - 89.9%; 8.3 - 14.6%; 0.1 - 1.9%; 1.1 - 2.7% and

Nurul Huda; Aminah Abdullah; Abdul Salam Babji

64

Chemical composition of infrared dark clouds: observations vs modeling  

NASA Astrophysics Data System (ADS)

In this work, we present our molecular line data for southern infrared dark clouds (IRDCs) and the first results of chemical modeling for these objects. Using the 22-m Mopra radio telescope, we performed observations toward 15 IRDCs in 13 molecular species. Where possible, we calculated molecular abundances. We uncovered a tendency for IRDCs to have molecular abundances similar to those in low-mass pre-stellar cores. This similarity may indicate similar chemical composition at the earliest stages of low- and high-mass stars and their close evolutionary status. However, for the N_2H^+ and HCO^+ species, there is a tendency for higher mean abundances in IRDCs compared with low-mass cores. To explain these features, we used chemical models including gas-phase reactions and accretion and desorption onto/from grains. Since the molecular line information for IRDC has been limited until recently, a comparison between observation and the results of realistic chemical models for IRDCs has been difficult to perform. Our Mopra data now allow us to study chemical evolution at the early stages of massive stars in more detail and reconstruct the physical conditions and evolutionary status of IRDCs.

Vasyunina, T.; Herbst, E.; Linz, H.; Henning, T.; Zinchenko, I.; Beuther, H.; Voronkov, M.

2011-05-01

65

Chemical Composition: Improving the Writing and Literature Searching Skills of Students in the Chemical Sciences.  

ERIC Educational Resources Information Center

Discusses a one-semester course offered in the School of Chemical Sciences at the University of Illinois at Urbana which incorporates technical writing and the use of the chemical literature into a single course. (CS)

Melhado, L. Lee

1980-01-01

66

Apparatus for rapid measurement of aerosol bulk chemical composition  

DOEpatents

An apparatus and method for continuous on-line measurement of chemical composition of aerosol particles with a fast time resolution are provided. The apparatus includes a modified particle size magnifier for producing activated aerosol particles and a collection device which collects the activated aerosol particles into a liquid stream for quantitative analysis by analytical methods. The method provided for on-line measurement of chemical composition of aerosol particles includes exposing aerosol carrying sample air to hot saturated steam thereby forming activated aerosol particles; collecting the activated aerosol particles by a collection device for delivery as a jet stream onto an impaction surface; flushing off the activated aerosol particles from the impaction surface into a liquid stream for delivery of the collected liquid stream to an analytical instrument for quantitative measurement.

Lee, Yin-Nan E. (East Setauket, NY); Weber, Rodney J. (Atlanta, GA)

2003-01-01

67

Composition and chemical structure of oceanic mantle plumes  

Microsoft Academic Search

The average compositions (including H2O, Cl, F, and S contents) and chemical structure of oceanic mantle plumes were estimated on the basis of the ratios of incompatible\\u000a volatile components, potassium, and some other elements in the basaltic magmas of ocean islands (melt inclusions and quenched\\u000a glasses). The following average concentrations were estimated for the plume mantle: 510 ppm K2O, 520

V. I. Kovalenko; V. B. Naumov; A. V. Girnis; V. A. Dorofeeva; V. V. Yarmolyuk

2006-01-01

68

Fabrication of fiber reinforced ceramic composites by chemical vapor infiltration  

Microsoft Academic Search

Ceramic fiber-ceramic matrix composites were prepared using the chemical vapor deposition (CVD) process. Our major goal of significantly reducing the infiltration times was accomplished. We have conceived a process, fabricated hardware, and demonstrated on a laboratory scale a process which permits CVD infiltration of an SiC fibrous preform with either an SiâNâ or SiC matrix in 2 to 12 h.

A. J. Caputo; W. J. Lackey

1984-01-01

69

Lemon Balm ( Melissa officinalis ) Stalk: Chemical Composition and Fiber Morphology  

Microsoft Academic Search

This work investigates the potentials of lemon balm (Melissa officinalis L.) stalk (LBS), a massive waste part of medicinal plant, for pulp and papermaking by assessing its fiber characteristics\\u000a and chemical composition. In addition, LBS properties were compared with some important agro-residues such as bagasse stalk\\u000a (BS), cotton stalk (CS) and tobacco stalk (TS). There is no information about suitability

Yahya Hamzeh; Fatemeh Amani

2011-01-01

70

Solar Models with Non-Standard Chemical Composition  

Microsoft Academic Search

The OPAL monochromatic opacity tables are used to evaluate the impact of a non-standard chemical composition on solar models.\\u000a \\u000a A calibrated solar model with consistent diffusion including the effect of radiative forces and ionization on drift velocities\\u000a is presented. It is shown that surface abundances are predicted to change slightly more than in traditional solar models where\\u000a these refinements are

S. Turcotte; J. Christensen-Dalsgaard

1998-01-01

71

Chemically bonded phosphate ceramics composites reinforced with graphite nanoplatelets  

Microsoft Academic Search

Chemically bonded phosphate ceramic (CBPCs) composites with 1.0wt.% graphite nanoplatelets (GNPs) reinforcement have been manufactured. The GNPs were functionalized by different procedures, a nitric acid oxidation and a dried oxidation in open air.Two different mixing techniques were used, Thinky and Resonant Acoustic Mixing (RAM). Results showed both techniques are effective to remove most of the air bubbles and a homogeneous

H. A. Colorado; C. Hiel; H. T. Hahn

2011-01-01

72

Carbon Nano Tube Composites with Chemically Functionalized Plant Oils  

NASA Astrophysics Data System (ADS)

Carbon Nano Tube Composites with Chemically Functionalized Plant Oil Wim Thielemans, R., P. Wool, V. Barron and W. Blau Multi-Wall Carbon Nano Tubes (MWCNT) made by the Kratchmer-Huffman CCVD process were found to interact and solubilize by slow mechanical stirring, with chemically functionalized plant oils, such as acrylated, epoxidized and maleinated triglycerides (TG) derived from plant oils. The chemical functionality on the TG imparted amphiphilic properties to the oils which allows them to self-assemble on the nanotubes, promoting both dissolution and the ability to make nanocomposites with unusual properties. Once in solution, the MWCT can be processed in a variety of methods, in particular to make composites with enhanced mechanical, fracture and thermal properties. Since the tensile modulus of MWs is about 1 TPa and a vector percolation analysis indicated tensile strengths of 50-100 GPa, we obtain significantly improved properties with even small amounts (1-3the glass transition temperature of the composite by about 20 oC, and the tensile modulus by about 11significant effects on the fracture stress can be obtained due to the both the influence of the strength and length of the MWNT at the crack tip. The ability of the oils to self-assemble on the carbon nanotube surfaces also makes them ideal candidates for self-healing materials. The properties with different functionalized oils will be reported. Supported by EPA, DoE and ISF

Thielemans, Wim; Wool, Richard P.; Blau, Werner; Barron, Valerie

2003-03-01

73

Measurements of aerosol chemical composition in boreal forest summer conditions  

NASA Astrophysics Data System (ADS)

Boreal forests are an important biome, covering vast areas of the northern hemisphere and affecting the global climate change via various feedbacks [1]. Despite having relatively few anthropogenic primary aerosol sources, they always contain a non-negligible aerosol population [2]. This study describes aerosol chemical composition measurements using Aerodyne Aerosol Mass Spectrometer (C-ToF AMS, [3]), carried out at a boreal forest area in Hyytiälä, Southern Finland. The site, Helsinki University SMEAR II measurement station [4], is situated at a homogeneous Scots pine (Pinus sylvestris) forest stand. In addition to the station's permanent aerosol, gas phase and meteorological instruments, during the HUMPPA (Hyytiälä United Measurements of Photochemistry and Particles in Air) campaign in July 2010, a very comprehensive set of atmospheric chemistry measurement instrumentation was provided by the Max Planck Institute for chemistry, Johannes Gutenberg-University, University of California and the Finnish Meteorological institute. In this study aerosol chemical composition measurements from the campaign are presented. The dominant aerosol chemical species during the campaign were the organics, although periods with elevated amounts of particulate sulfates were also seen. The overall AMS measured particle mass concentrations varied from near zero to 27 ?g/m observed during a forest fire smoke episode. The AMS measured aerosol mass loadings were found to agree well with DMPS derived mass concentrations (r2=0.998). The AMS data was also compared with three other aerosol instruments. The Marga instrument [5] was used to provide a quantitative semi-online measurement of inorganic chemical compounds in particle phase. Fourier Transform Infrared Spectroscopy (FTIR) analysis was performed on daily filter samples, enabling the identification and quantification of organic aerosol subspecies. Finally an Atmospheric Pressure Chemical Ionization Ion Trap Mass Spectrometer (APCI-IT-MS, [6]) was measuring gas and particle phase aerosol composition, offering additional information on molecular compositions. Overall, the availability of a variety of aerosol chemical characterization instruments provided a good opportunity for a comparison of the results obtained by these four very different measurement approaches. Overall the results were found to agree. The inorganic particulate masses measured with the AMS and Marga were found to correlate especially well for sulphates (r2=0.92) and ammonia compounds (r2=0.82). The organic mass seen by the AMS was correlated with the FTIR filter analysis (r2=0.87) and the APCI-IT-MS (r2=0.88).

?ijälä, M.; Junninen, H.; Ehn, M.; Petäjä, T.; Vogel, A.; Hoffmann, T.; Corrigan, A.; Russell, L.; Makkonen, U.; Virkkula, A.; Mäntykenttä, J.; Kulmala, M.; Worsnop, D.

2012-04-01

74

Chemical composition of exhaust from aircraft turbine engines  

SciTech Connect

This paper reports measurement of the chemical composition of exhaust from two aircraft tubing engines. The two engines are the F101, used on the B-1B aircraft, and the F110, used on the F-16C and F-16D aircraft. Samples were collected from each engine using a probe positioned just behind the exhaust nozzle. The measurements reported her were made at four power settings from idle to intermediate power. Exhaust composition measurements included carbon monoxide, carbon dioxide, nitrogen oxides, total hydrocarbons, and individual organic species. The principle focus of this paper is on the detailed organic species results.

Spicer, C.W.; Holdren, M.W.; Smith, D.L. (Battelle, Columbus, OH (US)); Hughes, D.P. (Tinker AFB, Oklahoma City, OK (US)); Smith, M.D. (Environics Div., Tyndall AFB, Panama City, FL (US))

1992-01-01

75

Vector Diagram of the Chemical Compositions of Tektites and Earth Lavas.  

National Technical Information Service (NTIS)

The chemical compositions of tektites and various volcanic glasses similar, in composition to tektites, were compared by the petrochemical method. The advantage of this method is that a large number of chemical analyses of igneous rocks can be graphically...

L. G. Kvasha G. S. Gorshkov

1973-01-01

76

Chemical Composition of Rainwater in Córdoba City, Argentina  

NASA Astrophysics Data System (ADS)

Sampling and chemical analysis of rainwater has proved to be a useful technique for studying its chemical composition and provides a greater understanding of local and regional dispersion of pollutants and their potential impacts to ecosystems through deposition processes. Samples of rainwater were collected during 2009-2012, in Córdoba city, Argentina. Two kind of sampling were performed: event-specific and sequential. The objective of the first of these was to determine the chemical concentration of the total rain, while the objective of the second one was to analyze the variability of the chemical concentration during an individual rain event. The total volume of each sample was divided in halves. One half was filtered through 0.45 ?m membrane filter. After this, all the samples were reduced by evaporation to a final volume of 10 ml. The non-filtered samples were acidified and digested in accordance to the method 3050B of the Environmental Protection Agency (EPA) for acid digestion of sediments. Multi-elemental standard solutions in different concentrations were prepared by adequate dilutions. Gallium was added as an internal standard in all standard solutions and samples. Exactly 5 ?L of these solutions were deposited on acrylic supports. When these droplets were dried, Synchrotron Radiation Total Reflection X-Ray Fluorescence technique was used for determining the chemical elements. Spectra were analyzed with the AXIL package for spectrum analysis. Due to the intrinsic characteristics of the total reflection technique, the background of the measurements is significantly reduced and there are no matrix effects, therefore quantification can be obtained from the linear correlation between fluorescence intensity and the concentration of the element of interest. The elements quantified were S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, and Pb. For all of them a calibration curve was performed in order to quantify their concentrations on the samples. The results show that the average pH in city rainwater was pH=6.5; the elements found in the samples were S, Ca, Cu, Cr, Sr, P, Fe, Mn, Pb, K, Ti, V, Zn and the average concentrations of these elements were below the limits established by World Health Organization for drinking water, and show a high natural variability. The temporal evolution of inorganic ion concentration during rain events was analyzed and the scavenging coefficients were calculated and compared with data from literature. A comparison was made between the rainwater chemical composition and chemical composition in the aerosols scavenging during the rain. This study is the first in Córdoba city to analyze the chemical composition of rainwater and constitute a base for future comparison of variability in pH and elemental composition.

López, M. L.; Asar, M. L.; Ceppi, S.; Bürgesser, R. E.; Avila, E.

2013-05-01

77

The Chemical Composition of Exoplanet-hosting Binary Star Systems  

NASA Astrophysics Data System (ADS)

A significant portion of stars occur as binary systems, in which two stellar components orbit a common center of mass. As the number of known exoplanet systems continues to grow, some binary systems are now known to harbor planets around one or both stellar components. As a first look into composition of these planetary systems, I investigate the chemical compositions of 4 binary star systems, each of which is known to contain at least one planet. Stars are known to vary significantly in their composition, and their overall metallicity (represented by iron abundance, [Fe/H]) has been shown to correlate with the likelihood of hosting a planetary system. Furthermore, the detailed chemical composition of a system can give insight into the possible properties of the system's known exoplanets. Using high-resolution spectra, I quantify the abundances of up to 28 elements in each stellar component of the binary systems 16 Cyg, 83 Leo, HD 109749, and HD 195019. A direct comparison is made between each star and its binary companion to give a differential composition for each system. For each star, a comparison of elemental abundance vs. condensation temperature is made, which may be a good diagnostic of refractory-rich terrestrial planets in a system. The elemental ratios C/O and Mg/Si, crucial in determining the atmospheric composition and mineralogy of planets, are calculated and discussed for each star. Finally, the compositions and diagnostics of each binary system are discussed in terms of the known planetary and stellar parameters for each system.

Carande, Bryce

78

Pyrolysis kinetics and chemical composition of Hazro coal according to the particle size  

Microsoft Academic Search

Summary The relationship between particle size and chemical composition of Hazro coal (origin: SE Anatolia, Turkey) has been examined by elemental analysis and by thermogravimetric pyrolysis. The chemical composition of the coal was determined by grinding sample particles physically and separating according to their size in mm by sieving. Particle size distribution of the coal and chemical composition of these

M. Z. Duz; Y. Tonbul; A. Baysal; O. Akba; A. Saydut; C. Hamamci

2005-01-01

79

Physical Characterization and Steam Chemical Reactivity of Carbon Fiber Composites  

SciTech Connect

This report documents experiments and analyses that have been done at the Idaho National Engineering and Environmental Laboratory (INEEL) to measure the steam chemical reactivity of two types of carbon fiber composites, NS31 and NB31, proposed for use at the divertor strike points in an ITER-like tokamak. These materials are 3D CFCs constituted by a NOVOLTEX preform and densified by pyrocarbon infiltration and heat treatment. NS31 differs from NB31 in that the final infiltration was done with liquid silicon to reduce the porosity and enhance the thermal conductivity of the CFC. Our approach in this work was twofold: (1) physical characterization measurements of the specimens and (2) measurements of the chemical reactivity of specimens exposed to steam.

Anderl, Robert Andrew; Pawelko, Robert James; Smolik, Galen Richard

2001-05-01

80

Determining the chemical composition of cloud condensation nuclei  

SciTech Connect

This second progress report describes the status of the project one and one-half years after the start. The goal of the project is to develop the instrumentation to collect cloud condensation nuclei (CCN) in sufficient amounts to determine their chemical composition, and to survey the CCN composition in different climates through a series of field measurements. Our approach to CCN collection is to first form droplets on the nuclei under simulated cloud humidity conditions, which is the only known method of identifying CCN from the background aerosol. Under cloud chamber conditions, the droplets formed become larger than the surrounding aerosol, and can then be removed by inertial impaction. The residue of the evaporated droplets represents the sample to be chemically analyzed. Two size functions of CCN particles are collected by first forming droplets on the large particles are collected by first forming droplets on the large CCN in a haze chamber at 100% relative humidity, and then activating the remaining CCN at 1% supersaturation in a cloud chamber. The experimental apparatus is a serious flow arrangement consisting of an impactor to remove the large aerosol particles, a haze chamber to form droplets on the remaining larger CCN, another impactor to remove the haze droplets containing the larger CCN particles for chemical analysis, a continuous flow diffusion (CFD) cloud chamber to form droplets on the remaining smaller CCN, and a third impactor to remove the droplets for the small CCN sample. Progress is documented here on the development of each of the major components of the flow system. Chemical results are reported on tests to determine suitable wicking material for the different plates. Results of computer modeling of various impactor flows are discussed.

Williams, A.L.; Rothert, J.E.; McClure, K.E. (Illinois State Water Survey, Champaign, IL (United States)); Alofs, D.J.; Hagen, D.E.; White, D.R.; Hopkins, A.R.; Trueblood, M.B. (Missouri Univ., Rolla, MO (USA). Cloud and Aerosol Science Lab.)

1992-02-01

81

Chem I Supplement: The Chemical Composition of the Cell.  

ERIC Educational Resources Information Center

Describes the principal chemical substances which occur in most cells. These chemicals are the lipids, carbohydrates, proteins, and nucleic acids. Suggests that the structures of these substances be taught first since structure determines function. (JN)

Holum, John R.

1984-01-01

82

The physical and chemical composition of the lower mantle.  

PubMed

This article reviews some of the recent advances made within the field of mineral physics. In order to link the observed seismic and density structures of the lower mantle with a particular mineral composition, knowledge of the thermodynamic properties of the candidate materials is required. Determining which compositional model best matches the observed data is difficult because of the wide variety of possible mineral structures and compositions. State-of-the-art experimental and analytical techniques have pushed forward our knowledge of mineral physics, yet certain properties, such as the elastic properties of lower mantle minerals at high pressures and temperatures, are difficult to determine experimentally and remain elusive. Fortunately, computational techniques are now sufficiently advanced to enable the prediction of these properties in a self-consistent manner, but more results are required.A fundamental question is whether or not the upper and lower mantles are mixing. Traditional models that involve chemically separate upper and lower mantles cannot yet be ruled out despite recent conflicting seismological evidence showing that subducting slabs penetrate deep into the lower mantle and that chemically distinct layers are, therefore, unlikely.Recent seismic tomography studies giving three-dimensional models of the seismic wave velocities in the Earth also base their interpretations on the thermodynamic properties of minerals. These studies reveal heterogeneous velocity and density anomalies in the lower mantle, which are difficult to reconcile with mineral physics data. PMID:16286292

Bovolo, C Isabella

2005-12-15

83

Values below detection limit in compositional chemical data.  

PubMed

Samples representing part of a whole, usually called compositional data in statistics, are commonplace in analytical chemistry--say chemical data in percentage, ppm, or ?g g(-1). Their distinctive feature is that there is an inherent relationship between all the analytes constituting a chemical sample as they only convey relative information. Some compositional data analysis principles and the log-ratio based methodology are outlined here in practical terms. Besides, one often finds that some analytes are not present in sufficient concentration in a sample to allow the measuring instruments to effectively detect them. These non-detects are usually labelled as "compositional data determines any data analysis and demands for a specialised treatment of less-thans that, unfortunately, is not usually covered in chemometrics. Some well-founded statistical methods are revisited in this paper aiming to prevent practitioners from relying on popular but untrustworthy approaches. A new proposal to estimate less-thans combining a log-normal probability model and a multiplicative modification of the samples is also introduced. Their performance is illustrated and compared on a real data set, and guidelines are provided for practitioners. Matlab and R code implementing the methods are made available for the reader. PMID:23374212

Palarea-Albaladejo, J; Martín-Fernández, J A

2013-02-18

84

Chemical Composition of the Essential Oils of Kewda and Ketaki  

Microsoft Academic Search

The chemical composition of the essential oils obtained by water distillation of the staminate inflorescences of Kewda (Pandanus fascicularisLam. var. fasicularis) and Ketaki (P.fascicularis Lam. var. Ketaki) are reported. The major components of kewda oil were found to be 2-phenethyl methyl ether (65.6–75.4%), terpinen-4-ol (11.7–19.5%), p-cymene (1.0–3.1%) and ?-terpineol (1.2–2.9%), while the major components of ketaki oil were 2-phenethyl methyl

Reeta Misra; P. K. Dash; Y. R. Rao

2000-01-01

85

Modeling of chemical vapor infiltration for composite fabrication  

SciTech Connect

We describe our ongoing efforts to develop a general, validated, 3-D, finite-volume model for the chemical vapor infiltration (CVI) process. The model simulates preform densification for both isothermal (ICVI) and forced flow-thermal gradient (FCVI) variations of the process, but is most useful for FCVI where specification and control of flow rates and temperature profiles are critical to rapid, uniform densification. The model has been validated experimentally for both ICVI and FCVI fabrication of SiC/SiC composites.

Starr, T.L. [Georgia Inst. of Tech., Atlanta, GA (United States); Besmann, T.M. [Oak Ridge National Lab., TN (United States)

1993-12-31

86

Unusual chemical compositions of noctilucent-cloud particle nuclei  

NASA Technical Reports Server (NTRS)

Two sounding rocket payloads were launched from the ESRO range in Sweden during a noctilucent cloud display. Large numbers of submicron particles were collected, most of which appear to be made up of a high density material coated with a low density material. Typical electron micrographs are shown. Particle chemical compositions have been measured by use of dispersive X-ray analysis equipment attached to an electron microscope and have revealed that most of the high density particle nuclei have atomic weights greater than iron.

Hemenway, C. L.

1973-01-01

87

VEGA Mission results and chemical composition of Venusian clouds  

NASA Astrophysics Data System (ADS)

Physical and chemical analyses of the clouds and atmosphere of Venus on the basis of Vega payload data have yielded a cloud-particle composition in which the presence of phosphoric acid straightforwardly accounts for the fact that the clouds extend down to the 33-km limit of Vega's spectrometric, nephelometric, and photometric instrumentation. Attention is given to the problem posed by the inconsistency of these results with the much lower or entirely absent phosphorus at other Venera and Pioneer Venus landing probe sites. P4O6 is the main phosphorus-bearing gas.

Krasnopolsky, V. A.

1989-07-01

88

Chemical composition of essential oil from Calligonum polygonoides Linn.  

PubMed

The essential oil from air dried buds and roots of Calligonum polygonoides Linn., has been extracted from dry steam distillation and analysed for chemical composition by gas chromatography-mass spectrometry. In total, 27 and 10 compounds were analysed qualitatively and quantitatively, accounting for 68.42% and 82.12% total contents of the essential oils of buds and roots, respectively. It contains a complex mixture of terpenoids, hydrocarbons, phenolic compounds, acid derivatives and ketones. The main component of essential oil was ethyl homovanillate (11.79%) in buds and drimenol (29.42%) in roots. PMID:22574752

Samejo, Muhammad Qasim; Memon, Shahabuddin; Bhanger, Muhammad Iqbal; Khan, Khalid Mohammed

2013-04-01

89

Chemical Composition of Wild-2 Dust Collected by Stardust  

NASA Astrophysics Data System (ADS)

The Stardust spacecraft collected dust from Comet Wild-2 in two forms: material distributed along tracks in aerogel capture cells and residue in impact craters. To analyze the chemical composition of these samples the tracks produced in the aerogel were extracted as keystones containing complete tracks. Twenty-six tracks were analyzed using an X-Ray Microprobe, providing x-ray fluorescence chemical analysis for elements having K-lines at energies high enough to permit escape from the overlying aerogel (S and the heavier elements, including the moderately-volatile trace elements Cu, Zn, and Ga). Two of these tracks were then split open, exposing the interior for analysis by TOF-SIMS (which allowed detection of the lighter elements, e.g., Mg and Al). Neither Si nor O could be determined for samples captured in the aerogel, since these are the major elements in the aerogel itself. The residue in craters in the Al-foil were analyzed by SEM-EDX and TOF-SIMS. The crater residues provide information on the important light elements (Mg and Si). By combining the results from the craters and the tracks, a comprehensive chemical analysis of the Wild-2 dust was possible. Preliminary Examination of the material indicates that: 1) For particles collected in the aerogel, a significant fraction of the incident mass is frequently deposited along the entry track, suggesting the individual Wild-2 dust particles that hit the aerogel were relatively weak aggregates. 2) The chemical composition of the terminal particle in the track is frequently significantly different from the composition of the material deposited along the track, 3) Most of the elements measured show variations in their Fe-normalized abundances of more than two orders-of-magnitude in both the terminal particles and the material deposited along track walls, indicating that the Wild-2 dust is compositionally heterogeneous at the size scale of the largest particles analyzed, not simply a well-mixed aggregate of sub-micron grains, 4) The mean content of the refractory, rock-forming elements (Mg, Ca, Si, Cr, Fe, and Ni) averaged over the whole tracks and/or the crater residues in the Wild-2 grains are approximately chondritic, and, 5) There is an apparent enrichment over CI in some of the moderately-volatile minor elements (Cu, Zn, and Ga) in the Wild-2 dust.

Flynn, G. J.

2006-12-01

90

Model atmospheres for cool stars. [varying chemical composition  

NASA Technical Reports Server (NTRS)

This report contains an extensive series of model atmospheres for cool stars having a wide range in chemical composition. Model atmospheres (temperature, pressure, density, etc.) are tabulated, along with emergent energy flux distributions, limb darkening, and information on convection for selected models. The models are calculated under the usual assumptions of hydrostatic equilibrium, constancy of total energy flux (including transport both by radiation and convection) and local thermodynamic equilibrium. Some molecular and atomic line opacity is accounted for as a straight mean. While cool star atmospheres are regimes of complicated physical conditions, and these atmospheres are necessarily approximate, they should be useful for a number of kinds of spectral and atmospheric analysis.

Johnson, H. R.

1974-01-01

91

Chemical composition of semi-regular variable giants. III.  

NASA Astrophysics Data System (ADS)

Aims: We derive the stellar atmosphere parameters and chemical element abundances of four stars classified as semi-regular variables of type "d" (SRd). These stars should presumably belong to the Galactic halo population. Methods: Elemental abundances are derived by applying both local thermodynamical equilibrium and non-local thermodynamical equilibrium analyses to high resolution (R ? 80 000) spectra obtained with the CFHT ESPaDOnS spectrograph. We determine the abundances of 27 chemical elements in VW Dra, FT Cnc, VV LMi, and MQ Hya. Results: The stars of our present program have a chemical composition that is inconsistent with their presumable status as metal-deficient halo giants. All studied SRd giants have relative-to-solar elemental abundances that are typical of the thick/thin Galactic disk stars. We find that all objects of this class for which spectroscopic follow up analyses have been completed show a dichotomy in the amplitudes of their photometric variations. Specifically, the disk objects have small amplitudes, while halo SRd stars have much larger amplitudes, which indicates that amplitude is obviously related to the metallicity of the star. Based on observations obtained at the Canada-France-Hawaii Telescope (CFHT), which is operated by the National Research Council of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii.Figures 2 and 3 are available in electronic form at http://www.aanda.org

Britavskiy, N. E.; Andrievsky, S. M.; Tsymbal, V. V.; Korotin, S. A.; Martin, P.; Andrievska, A. S.

2012-06-01

92

A bond-topological approach to theoretical mineralogy: crystal structure, chemical composition and chemical reactions  

NASA Astrophysics Data System (ADS)

Here, I describe a theoretical approach to the structure and chemical composition of minerals based on their bond topology. This approach allows consideration of many aspects of minerals and mineral behaviour that cannot be addressed by current theoretical methods. It consists of combining the bond topology of the structure with aspects of graph theory and bond-valence theory (both long range and short range), and using the moments approach to the electronic energy density-of-states to interpret topological aspects of crystal structures. The structure hierarchy hypothesis states that higher bond-valence polyhedra polymerize to form the (usually anionic) structural unit, the excess charge of which is balanced by the interstitial complex (usually consisting of large low-valence cations and (H2O) groups). This hypothesis may be justified within the framework of bond topology and bond-valence theory, and may be used to hierarchically classify oxysalt minerals. It is the weak interaction between the structural unit and the interstitial complex that controls the stability of the structural arrangement. The principle of correspondence of Lewis acidity-basicity states that stable structures will form when the Lewis-acid strength of the interstitial complex closely matches the Lewis-base strength of the structural unit, and allows us to examine the factors that control the chemical composition and aspects of the structural arrangements of minerals. It also provides a connection between a structure, the speciation of its constituents in aqueous solution and its mechanism of crystallization. The moments approach to the electronic energy density-of-states provides a link between the bond topology of a structure and its thermodynamic properties, as indicated by correlations between average anion coordination number and reduced enthalpy of formation from the oxides for [6]Mg{/m [4]}Si n O( m+2 n) and MgSO4(H2O) n .

Hawthorne, Frank C.

2012-11-01

93

Chemical Composition of Organic Aerosol Particles over the Remote Ocean  

NASA Astrophysics Data System (ADS)

Marine aerosol particles play an important role in Earth's radiative balance, yet the composition of the organic fraction of these important particles remains largely unconstrained. The composition of marine aerosol particles was measured in remote marine regions on board the R/V Atlantis during the CalNex 2010 campaign in May and June 2010, on board the R/V Point Sur during the E-PEACE campaign in July 2011, and on board the R/V Ronald Brown during the WACS campaign in August 2012. To understand the factors that control this composition, we compared the organic components of these particles to models of primary marine aerosol - i.e. those generated from bubbled and atomized seawater. The organic chemical composition was characterized by Fourier Transform Infrared (FTIR) spectroscopy to determine the functional group composition and high resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) to identify characteristic mass fragments. Cluster analysis of FTIR organic spectra was used to identify different spectral signatures associated with location, seawater composition, and ambient conditions. Typical submicron organic mass (OM) concentrations were less than 0.80 ?g m-3. The overall organic compositions of marine aerosol particles and generated seawater models were similar, with large fractions of organic hydroxyl functional groups in each. One cluster of FTIR spectra from the eastern Pacific showed the highest fraction of hydroxyl functional groups (77%) occurred during periods of high chlorophyll concentrations and high wind speeds (more than 10 m s-1). Detailed spectral comparisons revealed unique minor features that may be driven both by meteorology and regional differences in seawater composition for these and past studies.

Russell, L. M.; Frossard, A. A.; Keene, W. C.; Kieber, D. J.; Quinn, P.; Bates, T. S.

2012-12-01

94

Nanograined WC-Co Composite Powders by Chemical Vapor Synthesis  

NASA Astrophysics Data System (ADS)

Nanograined tungsten carbide (WC) Co composite powders were prepared by a chemical vapor synthesis (CVS) process that has previously been used for preparing the aluminides of titanium and nickel and other metallic and intermetallic powders at the University of Utah. To determine the optimum condition for producing nanograined WC-Co composite powders, the effects of carburization temperature, CH4 to WCl6 ratio, CH4 to H2 ratio, CoCl2 contents, and residence time of WC on the powder composition and particle size were investigated. The reduction and carburization of the vaporized chlorides by CH4-H2 mixtures produced nanograined WC and Co composite powder, which sometimes contained small levels of W2C, W, or the ? (Co3W3C) phase. The presence of these incompletely carburized phases can be tolerated because they can be fully carburized during the subsequent sintering process. These phases can also be fully carburized by a separate post-treatment. The products were characterized by using X-ray diffraction (XRD) and a transmission electron microscope (TEM). As a result, nanograined WC-Co composite with the particle size less than 30 nm was obtained.

Ryu, Taegong; Sohn, H. Y.; Han, Gilsoo; Kim, Young-Ugk; Hwang, Kyu Sup; Mena, M.; Fang, Zhigang Z.

2008-02-01

95

Switchgrass biomass and chemical composition for biofuel in eastern Canada  

SciTech Connect

Switchgrass (Panicum virgatum L.) is one of several warm-season grasses that have been identified as potential biomass crops in North America. A two-year field study was conducted, on a free-draining sandy clay loam (St. Bernard, Typic Hapludalf), to characterize the growth and evaluate changes in biomass accumulation and composition of switchgrass at Montreal, QC. Three cultivars, Cave-in-Rock, Pathfinder, and Sunburst, were grown in solid stands in a randomized complete block design. Canopy height, dry matter (DM) accumulation and chemical composition were monitored biweekly throughout the growing season. Average maximum canopy heights were 192.5 cm for Cave-in-Rock, 169.9 for Pathfinder, and 177.8 for Sunburst. The respective end-of-season DM yields were 12.2, 11.5, and 10.6 Mg/ha. Biomass production among cultivars appeared to be related to time of maturation. Nitrogen concentration of DM decreased curvilinearly from 25 g/kg at the beginning of the season to 5 g/kg DM at season's end. Both acid-detergent fiber (ADF) and neutral-detergent fiber (NDF) concentrations increased to a maximum early in the season, after which no changes were detected. The average maximum values of ADF and NDF were, respectively, 647.6 and 849.0 g/kg DM for Cave-in-Rock, 669.1 and 865.2 for Pathfinder, and 661.8 and 860.9 for Sunburst. Changes in canopy height, DM accumulation, and chemical composition could all be described by predictive regression equations. These results indicate that switchgrass has potential as a biomass crop in a short-season environment.

Madakadze, I.C.; Stewart, K.; Peterson, P.R.; Coulman, B.E.; Smith, D.L.

1999-08-01

96

Chemical composition of precipitation and its sources in Hangzhou, China.  

PubMed

To understand the origin and chemical characteristics of precipitation in Hangzhou, rainwater samples were collected from June 2006 to May 2008. All samples were analyzed for pH, electrical conductivity, and major ions (NH??, Ca²?, Mg²?, Na?, K?, SO?²?, NO??, F?, and Cl?). Acidification of precipitation in Hangzhou was serious with volume-weighted mean pH value of 4.5, while frequency of acid rain was 95%. The calculated SO?²?/NO?? ratio in Hangzhou precipitation was 2.87, which indicated that the precipitation of Hangzhou belonged to sulfate-based acid rain. The results of acid neutralization analysis showed that not all the acidity in the precipitation of Hangzhou was neutralized by alkaline constituents. The results of sea salt contribution analysis showed that nearly all SO?²?, Ca²?, and Mg²? and 33.7% of K? were of non-sea origins, while all Na? and Cl? and 66.3% of K? originated from sea sources. The principal component analysis which was used to analyze the sources of various ions indicated that chemical compositions of precipitation in Hangzhou mainly came from terrestrial sources, factory emissions, fuel wood burning, and marine sources. PMID:21380918

Xu, Hong; Bi, Xiao-Hui; Feng, Yin-Chang; Lin, Feng-Mei; Jiao, Li; Hong, Sheng-Mao; Liu, Wen-Gao; Zhang, Xiao-Yong

2011-12-01

97

Chemical composition of Mount St. Helens volcanic ash  

NASA Astrophysics Data System (ADS)

Volcanic ash samples from the May 18, 1980, Mount St. Helens eruption were analyzed for major, minor, and trace composition by a variety of analytical techniques. Results indicate that the basic composition of the ash consists of approximately 65% SiO2, 18% Al2O3, 5% FetO3, 2% MgO, 4% CaO, 4% Na2O, and 0.1% S. Thirty seven trace metals are reported including Ba, Cu, Mn, Sr, V, Zn, and Zr. A change in the chemical composition of the ash as a function of distance from the volcano is related to a similar change in physical characteristics of the ash. Water soluble components were also determined after column leaching experiments were performed. Concentration levels of soluble salts were found to be moderately high (1500-2000 µg/g) with molar ratios suggesting the presence of NaCl, KCl, CaSO4, and MgSO4. Heavy metals such as Cu, Co, Mn, and Zn were found at appreciable concentrations (10-1000 µg/g). Unexpectedly high concentration levels of ammonium (45 µg/g) and nitrate (100 µg/g) ions as well as dissolved organic carbon (130 µg/g) were observed in several ash leachates. Results for fluoride and boron show low average levels of ˜5 and ˜ 0.5µg/g, respectively.

Taylor, H. E.; Lichte, F. E.

1980-11-01

98

Optimum conditions for composites fiber coating by chemical vapor infiltration  

SciTech Connect

A combined analytical and numerical method is employed to optimize process conditions for composites fiber coating by chemical vapor infiltration (CVI). For a first-order deposition reaction, the optimum pressure yielding the maximum deposition rate at a preform center is obtained in closed form and is found to depend only on the activation energy of the deposition reaction, the characteristic pore size, and properties of the reactant and product gases. It does not depend on the preform specific surface area, effective diffusivity or preform thickness, nor on the gas-phase yield of the deposition reaction. Further, this optimum pressure is unaltered by the additional constraint of a prescribed deposition uniformity. Optimum temperatures are obtained using an analytical expression for the optimum value along with numerical solutions to the governing transport equations. These solutions account for both diffusive and advective transport, as well as both ordinary and Knudsen diffusion. Sample calculations are presented for coating preform fibers with boron nitride.

Griffiths, S.K.; Nilson, R.H.

1997-04-01

99

Optimum conditions for composites fiber coating by chemical vapor infiltration  

SciTech Connect

A combined analytical and numerical method is employed to optimize process conditions for composites fiber coating by chemical vapor infiltration. For a first-order deposition reaction, the optimum pressure yielding the maximum deposition rate at a preform center is obtained in closed form and is found to depend only on the activation energy of the deposition reaction, the characteristic pore size, and properties of the reactant and product gases. It does not depend on the preform specific surface area, effective diffusivity or preform thickness, nor on the gas-phase yield of the deposition reaction. Further, this optimum pressure is unaltered by the additional constraint of a prescribed deposition uniformity. Optimum temperatures are obtained using an analytical expression for the optimum value along with numerical solutions to the governing transport equations. These solutions account for both diffusive and advective transport, as well as both ordinary and Knudsen diffusion. Sample calculations are presented for coating preform fibers with boron nitride.

Griffiths, S.K.; Nilson, R.H. [Sandia National Labs., Livermore, CA (United States)

1998-04-01

100

Rapid fabrication of ceramic composite tubes using chemical vapor infiltration  

SciTech Connect

Ceramic composite tubes can be fabricated with silicon carbide matrix and Nicalon fiber reinforcement using forced flow-thermal gradient chemical vapor infiltration (FCVI). The process model GTCVI is used to design the equipment configuration and to identify conditions for rapid, uniform densification. The initial injector and mandrel design produced radial and longitudinal temperature gradients too large for uniform densification. Improved designs have been evaluated with the model. The most favorable approach utilizes a free-standing preform and an insulated water-cooled gas injector. Selected process conditions are based on the temperature limit of the fiber, matrix stoichiometry and reagent utilization efficiency. Model runs for a tube 12 inches long, 4 inches OD and 1/4 inch wall thickness show uniform densification in approximately 15 hours.

Starr, T.L.; Chiang, D. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering; Besmann, T.M.; Stinton, D.P.; McLaughlin, J.C.; Matlin, W.M. [Oak Ridge National Lab., TN (United States)

1996-06-01

101

Chemical compositions and glycemic responses to banana varieties.  

PubMed

Chemical compositions and glycemic indices of four varieties of banana (Musa spp.) (kolikuttu-Silk AAB, embul-Mysore AAB, anamalu-Gros Michel AAA, seeni kesel-Pisang Awak ABB) were determined. Silk, Gros Michel, Pisang Awak and Mysore contained the highest percentages of starch (14%), sucrose (38%), free glucose (29%) and fructose (58%) as a percentage of the total available carbohydrate content respectively. Total dietary fiber contents of four varieties ranged from 2.7 to 5.3%. Glycemic indices of Silk, Mysore, Gros Michel and Pisang Awak were 61 ± 5, 61 ± 6, 67 ± 7, 69 ± 9 and can be categorized as low against white bread as the standard. A single banana of the four varieties elicited a low glycemic load. Thus, consumption of a banana from any of these varieties can be recommended as a snack for healthy or diabetic patients who are under dietary management or pharmacological drugs to regulate blood glucose responses in between meals. PMID:21250902

Hettiaratchi, U P K; Ekanayake, S; Welihinda, J

2011-06-01

102

XPS analysis of combustion aerosols for chemical composition, surface chemistry, and carbon chemical state.  

PubMed

Carbonaceous aerosols can vary in elemental content, surface chemistry, and carbon nano-structure. Each of these properties is related to the details of soot formation. Fuel source, combustion process (affecting formation and growth conditions), and postcombustion exhaust where oxidation occurs all contribute to the physical structure and surface chemistry of soot. Traditionally such physical and chemical parameters have been measured separately by various techniques. Presented here is the unified measurement of these characteristics using X-ray photoelectron spectroscopy (XPS). In the present study, XPS is applied to combustion soot collected from a diesel engine (running biodiesel and pump-grade fuels); jet engine; and institutional, plant, and residential oil-fired boilers. Elemental composition is mapped by a survey scan over a broad energy range. Surface chemistry and carbon nanostructure are quantified by deconvolution of high-resolution scans over the C1s region. This combination of parameters forms a distinct matrix of identifiers for the soots from these sources. PMID:21322576

Vander Wal, Randy L; Bryg, Vicky M; Hays, Michael D

2011-03-15

103

Dictyostelium Cells Migrate Similarly on Surfaces of Varying Chemical Composition  

PubMed Central

During cell migration, cell-substrate binding is required for pseudopod anchoring to move the cell forward, yet the interactions with the substrate must be sufficiently weak to allow parts of the cell to de-adhere in a controlled manner during typical protrusion/retraction cycles. Mammalian cells actively control cell-substrate binding and respond to extracellular conditions with localized integrin-containing focal adhesions mediating mechanotransduction. We asked whether mechanotransduction also occurs during non-integrin mediated migration by examining the motion of the social amoeba Dictyostelium discoideum, which is thought to bind non-specifically to surfaces. We discovered that Dictyostelium cells are able to regulate forces generated by the actomyosin cortex to maintain optimal cell-surface contact area and adhesion on surfaces of various chemical composition and that individual cells migrate with similar speed and contact area on the different surfaces. In contrast, during collective migration, as observed in wound healing and metastasis, the balance between surface forces and protrusive forces is altered. We found that Dictyostelium collective migration dynamics are strongly affected when cells are plated on different surfaces. These results suggest that the presence of cell-cell contacts, which appear as Dictyostelium cells enter development, alter the mechanism cells use to migrate on surfaces of varying composition.

Wang, Chenlu; Losert, Wolfgang; Parent, Carole A.

2014-01-01

104

[Characteristics of chemical compositions of precipitation in Beijing].  

PubMed

Characteristics of chemical compositions of precipitation in Beijing were analyzed. The average value of pH was 5.19 from 2005 to 2009, showing stable characteristics of acidification with precipitation. The lowest annual average pH was 4. 87 in 2008 with the highest acidification frequency of 42% and 23% in Chegongzhuang and Daxing districts respectively. The inorganic ion concentrations declined in 5a, indicating an increasing improvement of air quality in Beijing. The concentrations of NH4+ and NO3- were found to increase and contributed to the high nitrogen amount in precipitation. Different seasons have influence on composition concentrations. Generally speaking, the ion concentrations in winter were higher that that in summer. SO4(2-) was the main factor responsible for the acidification of snow in winter, SO4(2-) and NO3- had similar contributions to the acidification of precipitation in summer. It was also found that the local pollutants of SO2, NO(x) and NH3 were major contributors to the acidification of precipitation in Beijing area, local geological conditions and long-distance transfers have important effects on the neutralization of the precipitation. PMID:21922802

Yang, Dong-Yan; Li, Xiu-Jinz; Chen, Yuan-Yuan; Zou, Ben-Dong; Lin, An-Guo

2011-07-01

105

Flaxseed Hull: Chemical Composition and Antioxidant Activity during Development.  

PubMed

Changes in the chemical composition and antioxidant activity of flaxseed hull during maturation were investigated. P129 hull variety was studied at four maturation stages (St1, St2, St3, and St4). Significant variation in proximate composition and flaxseed hull oil characteristics were observed. A significant increase in the carbohydrates content of the hull was observed during development. The main methyl esters were linolenic acid (48.95 - 51.52 %), oleic acid (20.27-23.41%) and linoleic acid (15.62-17.70%). The highest polyunsaturated fatty acids (PUFA) were found to be 67.14 % at the first stage of maturity (St1). Flaxseed hull oil was of good quality, containing an abundance of omega-3 essential fatty acids. The iodine value increased, while the saponification value of oil decreased during seed development. The decrease in ascorbic acid content was steady. The maximum level of total phenolic acid content (128.3 mg/100 g oil) was reached at 7 DAF. The antioxidant activity of oilseed was assessed by means of 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay. Radical scavenging activity for green hull was 52.74% and mature hull was 69.32%. PMID:24919478

Herchi, Wahid; Al Hujaili, Abdullah D; Sakouhi, Faouzi; Sebei, Khaled; Trabelsi, Hajer; Kallel, Habib; Boukhchina, Sadok

2014-06-27

106

Fabrication of fiber reinforced ceramic composites by chemical vapor infiltration  

SciTech Connect

Ceramic fiber-ceramic matrix composites were prepared using the chemical vapor deposition (CVD) process. Our major goal of significantly reducing the infiltration times was accomplished. We have conceived a process, fabricated hardware, and demonstrated on a laboratory scale a process which permits CVD infiltration of an SiC fibrous preform with either an Si/sub 3/N/sub 4/ or SiC matrix in 2 to 12 h. The process should be applicable to infiltration of fibrous preforms prepared by slurry molding, stacking of layers of cloth, or filament winding. Two types of composites (SiC-Si/sub 3/N/sub 4/ and SiC-SiC) have been produced at densities of about 2.0 Mg/m/sup 3/ which was near the desired range. A scheme has also been conceived whereby the new infiltration process could be used for fabrication of tubes or hollow cylinders. This is an important advance since the ability to fabricate tubes or hollow cylinders would offer the hope that the process could be used for fabrication of toughened, high-strength heat exchanger tubes, heat engine cylinder liners and valve guides. 19 references, 7 figures, 1 table.

Caputo, A.J.; Lackey, W.J.

1984-01-01

107

Chemical composition and coercivity of SmCo5 magnets  

NASA Astrophysics Data System (ADS)

The effects of alloy composition and heat treatment on the intrinsic coercivity iHc of SmCo5 magnets were studied. Alloys having six chemical compositions near that of stoichiometric SmCo5 were used to produce magnets via the usual powder metallurgy techniques. Magnets were either as sintered (1150 °C) or sintered (1150 °C) and treated at 850 °C. The substantial increase in iHc due to the 850 °C heat treatment occurs reversibly and with a negligible change in lattice parameters, Curie temperature Tc and anisotropy field HA. Quantitative metallography and thermomagnetic measurements showed that the microstructural constituent present in addition to the SmCo5 phase in hyperstoichiometric alloys is composed of both the Sm2Co7 phase and the Sm5Co19 phase. Measurements of magnetization in dc magnetic fields up to 33 T suggest that HA is around 53 T, considerably higher than previously reported values. The coercivity of the magnets is discussed in terms of thermal equilibrium populations of lattice defects.

de Campos, M. F.; Landgraf, F. J. G.; Saito, N. H.; Romero, S. A.; Neiva, A. C.; Missell, F. P.; de Morais, E.; Gama, S.; Obrucheva, E. V.; Jalnin, B. V.

1998-07-01

108

Chemical composition of bioactive pressurized extracts of Romanian aromatic plants.  

PubMed

In this contribution, pressurized liquid extraction (PLE) has been employed to isolate bioactive compounds from three native Romanian plants, oregano (Origanum vulgare), tarragon (Artemisia dracunculus) and wild thyme (Thymus serpyllum). Different PLE conditions have been tested including extraction with water, ethanol and their mixtures in a wide range of extraction temperatures (50-200°C), and the antioxidant capacity of the extracts was measured using different assays (DPPH radical scavenging, TEAC assay and Folin-Ciocalteau assay to measure total phenols). Moreover, a complete chemical characterization by using LC-MS/MS was carried out to be able to correlate the bioactivity with the particular chemical composition of each extract and plant. The use of PLE with water as a solvent at the highest temperature tested (200°C) always provided the highest extraction yields for the three studied plants, being maximum for oregano (>60%). Besides, oregano's pressurized water extracts at lower temperatures (50°C) presented the highest content on total phenols (184.9 mg gallic acid/g extract) and the best antioxidant activities (EC(50) 6.98 ?g/ml). In general, oregano extracts were the most active, followed by wild thyme extracts. The antioxidant capacity measured by DPPH assay was highly correlated with the amount of total phenols. Moreover, the use of a LC-MS/MS method allowed the identification of 30 different phenolic compounds in the different extracts, including phenolic acids, flavones, flavanones and flavonols, which have an important influence on the total antioxidant capacity of the different extracts. PMID:21163488

Miron, T L; Plaza, M; Bahrim, G; Ibáñez, E; Herrero, M

2011-07-29

109

Chemical composition and physicochemical properties of barley dietary fiber by chemical modification.  

PubMed

Chemical modification of dietary fiber (DF), extracted from whole grain barley, was carried out to obtain cross-linked (CL) DF, carboxymethyl (CM) DF, and hydroxypropyl (HP) DF. The DF components, physicochemical properties, and subsequent influence on the in vitro digestibility of wheat starch gels were comparatively investigated. The redistribution of fiber components from chemically modified DF was observed. An increase in the total DF (TDF) content of CL- and HP-DF was observed, which was mainly due to an increase of insoluble DF. Carboxymethylation led to an appreciable increase of soluble DF (1.17-6.20%) but TDF contents slightly decreased. Chemical modification of barley DF led to increases in arabinose (7.1-11.5%) and xylose (10.7-17.5%), but glucose contents decreased (67.4-79.9%). The treatments, especially carboxymethylation, effectively (P<0.05) increased hydration properties (e.g. water solubility, swelling power, and water absorption index). Substitution of 5% wheat starch with CL-, and HP-DF led to decreased in vitro digestibility in comparison to the control starch. Our results suggest that chemical modification improve the DF characteristics of barley and to exploit its potential application as a functional ingredient in fiber-rich products. PMID:23817090

Park, Ka Hwa; Lee, Kwang Yeon; Lee, Hyeon Gyu

2013-09-01

110

Chemical Methods for the Determination of Composition of Cryolite.  

National Technical Information Service (NTIS)

Preparation of uranium and plutonium alloys containing aluminium involves the use of cryolite and many times, cryolite which may be contaminated with alpha activity has to be analysed for its purity. In view of this, chemical methods for the determination...

V. Shivarudrappa B. N. Patil S. G. Marathe H. C. Jain

1989-01-01

111

CHEMICAL COMPOSITION OF EXHAUST PARTICLES FROM GAS TURBINE ENGINES  

EPA Science Inventory

A program was conducted to chemically characterize particulate emissions from a current technology, high population, gas turbine engine. Attention was focused on polynuclear aromatic compounds, phenols, nitrosamines and total organics. Polynuclear aromatic hydrocarbons (PAH) were...

112

RIVER TRANSPORT - INDUCED CHANGES IN CHEMICAL COMPOSITION OF ALLUVIAL GOLD (DOCUMENTED ON LOCALITIES THE WESTERN CARPATHIANS)  

Microsoft Academic Search

Alluvial gold is influenced by various physical, chemical and biological factors. As type- localities for study of changes in chemical composition of alluvial gold we chose Pukanec (Central Slovakia Neovolcanic Field) and Magurka and Ni?ná Boca (Nízke Tatry Mts). The most distinctive are morphological and chemical changes (dissolution and precipitation), the latter is most commonly represented by the formation of

B. BAHNA; A. SMIRNOV; M. CHOVAN; F. BAKOS

113

Exploring the chemical composition of water in the Kandalaksha Bay  

NASA Astrophysics Data System (ADS)

Oil films were noted at the head of the Kandalaksha Bay as far back as in 1971, as soon as the first stage of the oil tank farm had been commissioned (the autumn of 1970). In 1997-1998 there were accidental oil spills posing a real threat to the Kandalaksha Reserve biota. In May 2011, oil spills from the Belomorsk oil tank farm resulted in a local environmental emergency. In this work we have traced the evolution of polluted water by means of hydrogeochemical monitoring and reconstructing the chemical composition of surface and near-bottom water of the Kandalaksha Bay by using physical-chemical modeling (Selector software package, Chudnenko, 2010). The surface and near-bottom water was sampled in the summer of 2012 and 2013 at the following sites: under the numbers 3 (N 67.2.673, E 32.23.753); 4 (N 67.3.349, E 32.28.152); 1 (N 67.5.907, E 32.29.779), and 2 (N 67.6.429, E 32.30.539). The monitored objects and sampling time were sensitive to both the effects of the White Sea water (high tide), fresh water, and water affected by human impact (the oil tank farm). At each site, three samples were taken. The next stage involved reconstructing of the sea water ion composition by modeling within the Al-B-Br-Ar-He-Ne-C-Ca-Cl-F-K-Mg-Mn-N-Na-P-S-Si-Sr-Cu-Zn-H-O-e system, where e is an electron. Modeling of the chemical composition of near-bottom water (site 3) has revealed high contents of carbon dioxide, hydrogen disulphide, hydrocarbonates, and no oxygen (Eh<0). All this suggests a transformation of hydrocarbons that might have got to the sampling area in May 2011, or as the result of constant leakage of petroleum hydrocarbons from the oil tank farm. Sampling at site 4 in 2013 has revealed petroleum hydrocarbons both in surface (0.09 mg/l) and near-bottom (0.1 mg/l) water. Both monitoring and modeling have demonstrated that hydrobionts on areas adjoining the oil tank farm are far from prospering. Monitoring should be accompanied by express analysis of oxidizing conditions in both the soil and near-bottom water. Since the water contamination in the White Sea has lasted for decades, it is necessary to examine the near-bottom water, in particular in its deeper areas, to reveal the possible accumulation and destruction of organic substances at the sea floor. It is evident that an unbiased assessment of the environmental situation can be obtained by involving all kinds of information processing technologies.

Mazukhina, Svetlana; Masloboev, Vladimir; Chudnenko, Konstantin; Khaitov, Vadim; Maksimova, Victoria; Belkina, Natalia

2014-05-01

114

Composite-Material Tanks with Chemically Resistant Liners  

NASA Technical Reports Server (NTRS)

Lightweight composite-material tanks with chemically resistant liners have been developed for storage of chemically reactive and/or unstable fluids . especially hydrogen peroxide. These tanks are similar, in some respects, to the ones described in gLightweight Composite-Material Tanks for Cryogenic Liquids h (MFS-31379), NASA Tech Briefs, Vol. 25, No. 1 (January, 2001), page 58; however, the present tanks are fabricated by a different procedure and they do not incorporate insulation that would be needed to prevent boil-off of cryogenic fluids. The manufacture of a tank of this type begins with the fabrication of a reusable multisegmented aluminum mandrel in the shape and size of the desired interior volume. One or more segments of the mandrel can be aluminum bosses that will be incorporated into the tank as end fittings. The mandrel is coated with a mold-release material. The mandrel is then heated to a temperature of about 400 F (approximately equal to 200 C) and coated with a thermoplastic liner material to the desired thickness [typically approxiamtely equal to 15 mils (approximately equal to 0.38 mm)] by thermal spraying. In the thermal-spraying process, the liner material in powder form is sprayed and heated to the melting temperature by a propane torch and the molten particles land on the mandrel. The sprayed liner and mandrel are allowed to cool, then the outer surface of the liner is chemically and/or mechanically etched to enhance bonding of a composite overwrap. The etched liner is wrapped with multiple layers of an epoxy resin reinforced with graphite fibers; the wrapping can be done either by manual application of epoxy-impregnated graphite cloth or by winding of epoxy-impregnated filaments. The entire assembly is heated in an autoclave to cure the epoxy. After the curing process, the multisegmented mandrel is disassembled and removed from inside, leaving the finished tank. If the tank is to be used for storing hydrogen peroxide, then the liner material should be fluorinated ethylene/propylene (FEP), and one or more FEP O ring(s) should be used in the aluminum end fitting(s). This choice of materials is dictated by experimental observations that pure aluminum and FEP are the only materials suitable for long-term storage of hydrogen peroxide and that other materials tend to catalyze the decomposition of hydrogen peroxide to oxygen and water. Other thermoplastic liner materials that are suitable for some applications include nylon 6 and polyethylene. The processing temperatures for nylon 6 are lower than those for FEP. Nylon 6 is compatible with propane, natural gas, and other petroleum-based fuels. Polyethylene is compatible with petroleum- based products and can be used for short-term storage of hydrogen peroxide.

DeLay, Thomas K.

2004-01-01

115

Chemical Composition of Bottled Water in Saudi Arabia  

Microsoft Academic Search

Fourteen domestic and seven imported bottled water brands were analysed in Saudi Arabia for various physico-chemical water quality parameters. The results of the analysis were compared with the drinking water standards set by Saudi Arabia and World Health Organization. The levels of different physico-chemical parameters like TDS, Ca, Mg, Na, K, NO3, Cl and SO4 of all local and imported

Abdulrahman I. Alabdula'aly; Mujahid A. Khan

1999-01-01

116

Chemical composition and antigenotoxic properties of Lippia alba essential oils  

PubMed Central

The present work evaluated the chemical composition and the DNA protective effect of the essential oils (EOs) from Lippia alba against bleomycin-induced genotoxicity. EO constituents were determined by Gas Chromatography/Mass Spectrometric (GC-MS) analysis. The major compounds encountered being citral (33% geranial and 25% neral), geraniol (7%) and trans-?-caryophyllene (7%) for L. alba specimen COL512077, and carvone (38%), limonene (33%) and bicyclosesquiphellandrene (8%) for the other, COL512078. The genotoxicity and antigenotoxicity of EO and the compounds citral, carvone and limonene, were assayed using the SOS Chromotest in Escherichia coli. The EOs were not genotoxic in the SOS chromotest, but one of the major compound (limonene) showed genotoxicity at doses between 97 and 1549 mM. Both EOs protected bacterial cells against bleomycin-induced genotoxicity. Antigenotoxicity in the two L. alba chemotypes was related to the major compounds, citral and carvone, respectively. The results were discussed in relation to the chemopreventive potential of L. alba EOs and its major compounds.

Lopez, Molkary Andrea; Stashenko, Elena E.; Fuentes, Jorge Luis

2011-01-01

117

Chemical and radioactive composition of bulk deposition in Málaga (Spain)  

NASA Astrophysics Data System (ADS)

Chemical and radioactive composition of bulk deposition samples, which were collected monthly over a 5 year period (January 2007 until 31 December 2011) at a site located 30 m.a.l. in Málaga (4°28? 8?W; 36°43? 40?N) have been analysed. All samples were analysed for pH, major ions and gamma radionuclides. The average pH of bulk deposition was 6.4. Cl- and SO were the main anions, while Ca+ and Na+ were the main cations. Significant correlations were found in soil-derived species among Ca2+, Mg2+ and K+ and sea-salt species between Na+ and Cl-. Other relatively good correlations were also observed between acidic anions (SOandNO) and crustal-derived cations (Ca2+, Na+, K+). Sources of the major ions were assessed based on the enrichment factor method. The radionuclides present in all samples are 7Be and 210Pb and 40K appears in 50% of the samples. Relatively poor correlations were observed between the specific activities of gamma radionuclides and the major ions. The temporal variations of major ions and radionuclides exhibit similar seasonal behaviour with low values in winter-autumn months and maximum values in spring-summer months. The fluxes of major ions and gamma radionuclides have been discussed with meteorological factors controlling depositions.

Dueñas, C.; Fernández, M. C.; Gordo, E.; Cañete, S.; Pérez, M.

2012-12-01

118

Chemical composition, antifungal and insecticidal activities of Hedychium essential oils.  

PubMed

The antimicrobial properties of essential oils have been documented, and their use as "biocides" is gaining popularity. The aims of this study were to analyze the chemical composition and assess the biological activities of Hedychium essential oils. Oils from 19 Hedychium species and cultivars were analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) techniques. The antifungal and insecticidal activities of these oils were tested against Colletotrichum acutatum, C. fragariae, and C. gloeosporioides, and three insects, the azalea lace bug (Stephanitis pyrioides), the yellow fever mosquito (Aedes aegypti), and the red imported fire ant (Solenopsis invicta). Hedychium oils were rich in monoterpenes and sesquiterpenes, especially 1,8-cineole (0.1%-42%), linalool (<0.1%-56%), a-pinene (3%-17%), b-pinene (4%-31%), and (E)-nerolidol (0.1%-20%). Hedychium oils had no antifungal effect on C. gloeosporioides, C. fragariae, and C. acutatum, but most Hedychium oils effectively killed azalea lace bugs. The oils also show promise as an adult mosquito repellent, but they would make rather poor larvicides or adulticides for mosquito control. Hedychium oils acted either as a fire ant repellent or attractant, depending on plant genotype and oil concentration. PMID:23579997

Sakhanokho, Hamidou F; Sampson, Blair J; Tabanca, Nurhayat; Wedge, David E; Demirci, Betul; Baser, Kemal Husnu Can; Bernier, Ulrich R; Tsikolia, Maia; Agramonte, Natasha M; Becnel, James J; Chen, Jian; Rajasekaran, Kanniah; Spiers, James M

2013-01-01

119

Chemical Emergencies  

MedlinePLUS

... the case of a terrorist attack with a chemical weapon. Some hazardous chemicals have been developed by military ... there are no guarantees of safety during a chemical emergency, you can take actions to protect yourself. You ...

120

Chemical composition of sediments from White Sea, Russian Arctic  

NASA Astrophysics Data System (ADS)

The White Sea, the only Russian inland sea, is located on the north of outlying districts of the European part of Russia, belongs to Arctic Ocean. Area of water of sea occupies about 90 tousend square kilometers. The sea can be divided into some general parts: neck, funnel, basin and 4 Bays: Dvina Bay, Kandalaksha Bay, Mezen Bay and Onega Bay. The purpose of this work was geochemical mapping of the surface sediments of this area. The main tasks were: compilation data base of element composition of the surface sediments, geochemical mapping of each element, research of the anormal concentration of elements on the surface. To detect the content of chemical elements several methods were used: atomic absorption spectrometry (P.P. Shirshov Institute of Oceanology); neutron activation analysis (Vernadsky Institute of Geochemistry and Analytical Chemistry), total and organic carbon analysis, photometric method to detection Si, Al, P (P.P. Shirshov Institute of Oceanology). Bulk composition is one of the fundamental characteristics of sediments and bottom deposites of modern basins. Coarse-grained sediments with portion of pelitic component <50% is spread on the shallow area (Kandalaksha Bay), in areas with high hydrodynamic activity of near-bottom water. Under the conditions of their low activity, fine-grained facies are common(>80%). Character of elements distribution correlates with facial distribution of sediments from White Sea. According to litologic description, bottom surface of Dvina Bay is practically everywhere covered by layer of fine-grained sand. In the border area between Dvina Bay and White Sea basin on terraced subwater slope aleurite politic silts are abundant. They tend to exhange down the slope to clay silts. In Onega Bay fractions of non-deposition are observed. They are characterized by wide spread of thin blanket poorgraded sediments, which are likely to be relic. Relief of Kandalakscha Bay bottom is presented as alternation of abyssal fosses (near 300 m) with silles and elevations (<20 m), and also numerous islands. Thus variety of sediment composition is observed here - from rules and gravels to fine-grained clay silts [1]. The map of distribution of chemical elements was created by using bulk composition data with the help of program ArcView. Mn distribution in sedimentation mass is largely determed by influence of redox diagenesis. Reactive form of Mn dominates over less moving, litogenic form in sedimation mass of White Sea. Litogenic form remains in sediment, reactive form moves into silt near-bottom water, resulting Mn migration both in sediment and near-bottom layer of marine water. Mn oxidizes on the contact with oxygen of marine water and alters into insoluble form MnO2, causing Mn enrichment of surface layer of sediments. Highly movable silt deposit MnO2 and enriched by Mn suspension are moved by underflow and accumulate in bottom depressions and in central part of the sea, which is quite wide from both places of original sedimentation and run off sources [2]. Thus, the interrelation between granulometric composition of sediment and materials concentration can be shown by the example of Mn. Local conditions, leading to accumulation of clastic components, are: 1. Rise of content in sand owning to separation of heavy minerals 2. Rise of content in surface, mainly sandy clay sediments owning to presence of concretions 3. Rise of content in lower bunches roof owning to diagenetic contraction. Authors thank academic Lisitsyn for encourage, Andrey Apletalin for valuable help, and everybody, who helped in field and laboratory research of the White sea sediments. Work was being done under the auspices of Russian foundation of basic research (grants 09-05-10081, 09-05-00658 and 08-05-00860), RSA presidiums program of 17 fundamental researches (project 17.1). References: 1.Kuzmina T., Lein A., Lutchsheva L., Murdmaa I., Novigatsky A., Shevchenko V. Chemical composition of White Sea's sediments // Litology and mineral deposits . 2009. - ? 2. - P 115-132. 2.Nevessky E., Medvedev V. , Kalin

Gamza, Olga; Shevchenko, Vladimir; Novigatsky, Aleksandr

2010-05-01

121

Influence of mineral and chemical composition of coal ashes on their fusibility  

Microsoft Academic Search

The relationships between ash-fusion temperature (AFT) and mineral and chemical composition of coals and coal ashes from a wide variety of deposits (41) were studied by a melting test. X-ray diffractometry, light microscopy, differential-thermal, thermogravimetric and chemical analyses. A reliable explanation and prediction of AFT only from the total chemical composition of coal ash is inadequate because most important are

Stanislav V. Vassilev; Kunihiro Kitano; Shohei Takeda; Takashi Tsurue

1995-01-01

122

Carbon\\/silicon carbide composites prepared by chemical vapor infiltration combined with silicon melt infiltration  

Microsoft Academic Search

In order to reduce processing costs and improve the thermal stability of three-dimensional carbon fiber-reinforced silicon carbide composites, a chemical vapor infiltration combined with silicon melt infiltration method was developed for fabricating composites. According to the size of the pores in the preform, chemical vapor infiltration (CVI) and silicon melt infiltration (SMI) were mainly used to infiltrate small pores between

Yongdong Xu; Laifei Cheng; Litong Zhang

1999-01-01

123

Chemical composition of soils and plant species in the Polar Urals as influenced by rock type  

Microsoft Academic Search

The concentrations of chemical elements in tundra soils and plants of ultramafic and acid rocks were investigated in the Polar Urals. The close dependence of the soil concentrations of elements on the granulometric composition of the soils was shown and also the relationship of their chemical composition with that of the underlying bedrock including the predominance of magnesium over calcium

Maria N. Kataeva; Natalya V. Alexeeva-Popova; Irina V. Drozdova; Alla I. Beljaeva

2004-01-01

124

Thermomechanical properties of chemically modified graphene\\/poly(methyl methacrylate) composites made by in situ polymerization  

Microsoft Academic Search

The morphology and thermomechanical properties of composites of poly(methyl methacrylate) (PMMA) and chemically modified graphene (CMG) fillers were investigated. For composites made by in situ polymerization, large shifts in the glass transition temperature were observed with loadings as low as 0.05wt.% for both chemically-reduced graphene oxide (RG-O) and graphene oxide (G-O)-filled composites. The elastic modulus of the composites improved by

Jeffrey R. Potts; Sun Hwa Lee; Todd M. Alam; Jinho An; Meryl D. Stoller; Richard D. Piner; Rodney S. Ruoff

2011-01-01

125

Local chemical composition of nanophase-separated polymer brushes.  

PubMed

Using scattering scanning nearfield infrared microscopy (s-SNIM), we have imaged the nanoscale phase separation of mixed polystyrene-poly(methyl methacrylate) (PS-PMMA) brushes and investigated changes in the top layer as a function of solvent exposure. We deduce that the top-layer of the mixed brushes is composed primarily of PMMA after exposure to acetone, while after exposure to toluene this changes to PS. Access to simultaneously measured topographic and chemical information allows direct correlation of the chemical morphology of the sample with topographic information. Our results demonstrate the potential of s-SNIM for chemical mapping based on distinct infrared absorption properties of polymers with a high spatial resolution of 80 nm × 80 nm. PMID:21594259

Filimon, M; Kopf, I; Schmidt, D A; Bründermann, E; Rühe, J; Santer, S; Havenith, M

2011-06-28

126

The Chemical Composition of Fogs and Clouds in Southern California.  

NASA Astrophysics Data System (ADS)

Fog and clouds are frequent occurrences in Southern California. Their chemical composition is of interest due to their potential role in the transformation of sulfur and nitrogen oxides to sulfuric and nitric acid and in the subsequent deposition of those acids. In addition, cloud and fog droplets may be involved in the chemistry of low-molecular-weight carboxylic acids and carbonyl compounds. The major inorganic species in cloud and fogwater samples were NH_4^+, H ^+, NO_3^-, and SO_4^{2-}. Concentrations in fogwater samples were 1-10 times 10^ {-3} M; pH values ranged from ~eq2 to 6. Nitrate usually exceeded sulfate. Acidity depended on the availability of of NH_3 from agricultural operations. Stratus cloudwater had somewhat lower concentrations; pH values were in the range 3-4. The major factors accounting for variation in fog- or cloudwater composition were the preexisting aerosol and gas concentrations and variations in liquid water content. Deposition and entrainment or advection of different air masses were also important during extended cloud or fog episodes. The droplet size dependence of cloudwater composition was investigated on one occasion in an intercepted coastal stratus clouds. The observations were consistent with the hypothesis that small droplets form on small secondary aerosol composed of H_2SO _4, HNO_3, and their NH_4^+ salts, while large droplets form on large sea-salt and soil-dust aerosol. Species that can exist in the gas phase, such as HCl and HNO _3, may be found in either droplet-size fraction. Concentrations of S(IV) and CH_2 O in the range 100-1000 ?m were observed in fogwater from urban sites in Southern California. Lower concentrations were observed in stratus clouds. The high levels of S(IV) and CH_2 O were attributed to the formation of hydroxymethanesulfonate (HMSA), the S(IV) adduct of CH_2O. Direct measurement of HMSA in fogwater samples from Bakersfield, CA were made by ion-pairing chromatography. Glyoxal and methylglyoxal were observed at concentrations comparable to CH_2O in fogwater samples from Riverside, CA and in stratus cloudwater samples from sites along the Santa Barbara Channel.

Munger, James William

127

Lunar clinopyroxenes: Chemical composition, structural state, and texture  

USGS Publications Warehouse

Single-crystal x-ray diffraction, microprobe, optical and electron optical examinations of clinopyroxenes from Apollo 11 lunar samples 10003, 10047, 10050, and 10084 show that generally the crystals are composed of (001) augite-pigeonite intergrowths in varying ratios. Transmission electron micrographs reveal abundant exsolution lamellae, many only 60 A?? thick. In addition to the phase inhomogeneities, primary chemical inhomogeneities are clearly demonstrated. There are reciprocal relationships between calcium and iron and between Ti4+ + 2Al and R2+ + 2Si. Our evidence suggests that a chemically inhomogeneous subcalcic C2/c augite was the only primary pyroxene from which pigeonite later exsolved.

Ross, M.; Bence, A. E.; Dwornik, E. J.; Clark, J. R.; Papike, J. J.

1970-01-01

128

Anisotropy vs chemical composition at ultra-high energies  

NASA Astrophysics Data System (ADS)

This paper proposes and discusses a test of the chemical composition of ultra-high energy cosmic rays that relies on the anisotropy patterns measured as a function of energy. In particular, we show that if one records an anisotropy signal produced by heavy nuclei of charge Z above an energy Ethr, one should record an even stronger (possibly much stronger) anisotropy at energies >Ethr/Z due to the proton component that is expected to be associated with the sources of the heavy nuclei. This conclusion remains robust with respect to the parameters characterizing the sources and it does not depend at all on the modelling of astrophysical magnetic fields. As a concrete example, we apply this test to the most recent data of the Pierre Auger Observatory. Assuming that the anisotropy reported above 55 EeV is not a statistical accident, and that no significant anisotropy has been observed at energies lesssim10 EeV, we show that the apparent clustering toward Cen A cannot be attributed to heavy nuclei. Similar conclusions are drawn regarding the apparent excess correlation with nearby active galactic nuclei. We then discuss a robust lower bound to the magnetic luminosity that a source must possess in order to be able to accelerate particles of charge Z up to 100 EeV, LB gtrsim 1045 Z-2 erg/s. Using this bound in conjunction with the above conclusions, we argue that the current PAO data does not support the model of cosmic ray origin in active radio-quiet or even radio-loud galaxies. Finally, we demonstrate that the apparent clustering in the direction of Cen A can be explained by the contribution of the last few gamma-ray bursts or magnetars in the host galaxy thanks to the scattering of the cosmic rays on the magnetized lobes.

Lemoine, Martin; Waxman, Eli

2009-11-01

129

The Chemical Composition of Globular Cluster M68  

NASA Astrophysics Data System (ADS)

We present a chemical composition study of twenty-five stars in the metal-poor Galactic globular cluser M68. We obtained high-resolution spectra (R 40,000) in the wavelength region 3500-9000 A for the target stars with the the Magellan Inamori Kyocera Echelle (MIKE). The observed stars include 11 red giant branch (RGB) stars, 9 red horizontal branch (RHB) stars, and 5 blue horizontal branch (BHB) stars, which span an effective temperature range of approximately 5000K. The abundances were determined through equivalent width and synthetic spectrum analyses. The computations considered isotropic, coherent scattering in the continuum source functions. Sample stars from each group were analyzed using model atmospheres from the MARCS and ATLAS grids. We find a generally consistent metallicity across all the evolutionary groups: [Fe/H] = -2.4 (RMS deviation = 0.1). However, we note that the mean RHB metallicity is 0.15 dex less than the overall average. The relative abundance ratios of the alpha elements are typical for low metallicity stars: [Ca/Fe] = [Ti/Fe] +0.35, with only small variations among the RGB, RHB, and BHB stars. Star-to-star variations in proton-capture elements Na, O, and Al are apparent in the spectra. We will present representative abundances from other major element groups in all three stellar evolutionary domains. Acknowledgements: we are grateful to NSF grant AST-0908978, the University of Texas John W. Cox Endowment for Advanced Studies in Astronomy, and the University of Texas Astronomy Department Rex G. Baker, Jr. Endowment for support of this project.

Simmons, Sloane K.; Sneden, C.; Preston, G.; Thompson, I.; Sobeck, J.; Shectman, S.

2011-01-01

130

Brazilian Propolis: Correlation Between Chemical Composition and Antimicrobial Activity  

PubMed Central

The chemical composition of ethanol extracts from samples of Brazilian propolis (EEPs) determined by HPLC and their activity against Trypanosoma cruzi, Staphylococcus aureus, Streptococcus pneumoniae, Klebisiella pneumoniae, Candida albicans, Sporothrix schenckii and Paracoccidioides brasiliensis were determined. Based on the predominant botanical origin in the region of samples' collection, the 10 extracts were separated into three groups: A (B. dracunculifolia + Auraucaria spp), B (B. dracunculifolia) and C (Araucaria spp). Analysis by the multiple regression of all the extracts together showed a positive correlation, higher concentrations leading to higher biological effect, of S. aureus with p-coumaric acid (PCUM) and 3-(4-hydroxy-3-(oxo-butenyl)-phenylacrylic acid (DHCA1) and of trypomastigotes of T. cruzi with 3,5-diprenyl-4-hydroxycinnamic acid derivative 4 (DHCA4) and 2,2-dimethyl-6-carboxyethenyl-2H-1-benzopyran (DCBEN). When the same approach was employed for each group, due to the small number of observations, the statistical test gave unreliable results. However, an overall analysis revealed for group A an association of S. aureus with caffeic acid (CAF) and dicaffeoylquinic acid 3 (CAFQ3), of S. pneumoniae with CAFQ3 and monocaffeoylquinic acid 2 (CAFQ2) and of T. cruzi also with CAFQ3. For group B, a higher activity against S. pneumoniae was associated DCBEN and for T. cruzi with CAF. For group C no association was observed between the anitmicrobial effect and any component of the extracts. The present study reinforces the relevance of PCUM and derivatives, especially prenylated ones and also of caffeolyquinic acids, on the biological activity of Brazilian propolis.

Salomao, Kelly; Pereira, Paulo Roberto S.; Campos, Leila C.; Borba, Cintia M.; Cabello, Pedro H.; Marcucci, Maria Cristina

2008-01-01

131

Chemical composition of phosphorites of the Phosphoria Formation  

USGS Publications Warehouse

The chemical composition, both major and minor constituents, of 60 samples of phosphorite from the Phosphoria Formation was determined. Major constituents of the average phosphorite are, by weight per cent: SiO2, 11??9; Al2O3, 1??7; Fe2O3,1??1; MgO, 0??3; CaO, 44??0; Na2O, 0??6; K2O, 0??5; total H2O, 2??2; H2O-, 0??6; TiO2, 0??1; P2O5, 30??5; CO2, 2??2; SO3, 1??8; F, 3??1; organic matter, 2??1; and oil, 0??2. Uranium averages 0??009 per cent. The phosphate mineral is basically apatite, Ca5(PO4)3F, with small but significant and variable substitutions-Na, Sr, U and Th for Ca, and CO3 and SO4 for PO4. Rare metals not associated with apatite are associated principally with the organic-matter component of the rocks. This group includes As, Ag, Cd, Cr, Cu, Mo, Ni, Sb, Se, V and Zn. Chromium is the most abundant, having a modal abundance of 0??1 per cent and a maximum concentration of 0??3 per cent. The average phosphorite is composed of approximately 80 per cent apatite, 10 per cent quartz, 5 per cent muscovite-illite, 2 per cent organic matter, 1 per cent dolomite-calcite, 1 per cent iron oxide, and 1 per cent other components. It is texturally a medium-grained pellet phosphorite. ?? 1966.

Gulbrandsen, R. A.

1966-01-01

132

Effect of Amine Activators on the Properties of Chemical Cured Dental Composites  

Microsoft Academic Search

The purpose of this study was to evaluate the reactivity and the effect of concentration of three tertiary amines upon the mechanical properties of a chemical curing dental composite. Chemical cured composite pastes were prepared by keeping peroxide concentration constant at 1 wt% (by weight of resin mixture) and by varying the amine\\/peroxide molar ratio from 0.25 to 1.5. Composite

Leny Mathew; Roy Joseph; V. Kalliyana Krishnan

1997-01-01

133

On the chemical composition of L-chondrites  

NASA Technical Reports Server (NTRS)

Radiochemical neutron activation analysis of Ag, As, Au, Bi, Co, Cs, Ga, In, Rb, Sb, Te, Tl, and Zn and major element data in 14 L4-6 and 3 LL5 chondrites indicates that the L group is unusually variable and may represent at least 2 subgroups differing in formation history. Chemical trends in the S/Fe rich subgroup support textural evidence indicating late loss of a shock formed Fe-Ni-S melt; the S/Fe poor subgroup seemingly reflects nebular fractionation only. Highly mobile In and Zn apparently reflect shock induced loss from L chondrites. However, contrasting chemical trends in several L chondrite sample sets indicate that these meteorites constitute a more irregular sampling of, or more heterogeneous parent material than do carbonaceous or enstatite chondrites. Data for 15 chondrites suggest higher formation temperatures and/or degrees of shock than for LL5 chondrites.

Neal, C. W.; Dodd, R. T.; Jarosewich, E.; Lipschutz, M. E.

1980-01-01

134

The Chemical Composition of Damped Lyman-alpha Galaxies  

NASA Astrophysics Data System (ADS)

Absorption lines in quasar spectra probe interstellar gas in galaxies at various stages of evolution. They should thus provide powerful probes of the history of star formation and chemical enrichment in galaxies. A major obstacle in trying to understand the evolution of the strong quasar absorption lines known as the damped Lyman-alpha absorbers (DLAs) has been the small number of metallicity measurements at redshifts z < 1.5, an epoch spanning 70 % of the cosmic history. In recent surveys, we have significantly expanded the metallicity samples for DLAs as well as those for the sub-DLAs at z < 1.5. We will discuss the results of these studies and their implications for the chemical evolution of the absorber galaxies. We will also discuss the star formation rates in absorber galaxies. Our studies of low-z DLAs are helping to understand the nature of the absorber galaxies and their relation to present-day galaxies.

Kulkarni, V. P.

2007-12-01

135

Chemical vapor infiltration: Dispersed and graded depositions for ceramic composites  

Microsoft Academic Search

A structured-geometry model for dispersed and graded deposits was developed for chemical vapor infiltration of multiply-woven substrates of carbon filters. An earlier model was modified to allow for two reactants in the feed. The model predicts gas-phase concentration profiles in the voids of substrates and deposition amounts of two reactants as a function of time and location. Results are shown

G. Y. Chung; B. J. McCoy; J. M. Smith; Domenick E. Cagliostro

1993-01-01

136

Effects of Chemical Composition on X-Ray Lines  

Microsoft Academic Search

The influence of chemical combination with oxygen on the width, index of asymmetry and separation and ratio of peak intensities of the alpha-doublet of the elements Ti, Cr, Mn, Fe and Zn of the K-series emission lines has been studied with a double crystal spectrometer. The widths of the alpha-lines were increased 3 to 35 percent and the beta-lines were

Horace H. Roseberry; J. A. Bearden

1936-01-01

137

Irradiation of ‘Boufeggous’ dates: Effects on chemical composition during storage  

Microsoft Academic Search

Moroccan dates Phoenix dactylifera L. cv. Boufeggous were treated with 0.6, 0.9 and 1.8kGy of gamma irradiation and subsequently stored at ambient temperatures. Chemical properties were evaluated for irradiated and non-irradiated dates immediately after the treatment, 4 and 8 months of storage. No significant changes were noted in dry matter, total lipid and protein contents. Irradiation at higher doses (0.9

Khalid Azelmat; Driss ElGarrouj; Mohammed Mouhib; Fouad Sayah

2006-01-01

138

Chemical composition of giants from two moving groups  

NASA Astrophysics Data System (ADS)

We present the stellar parameters of 19 K-type giants and their abundances for 13 chemical elements (Al, Ba, Ca, Fe, K, Mg, Mn, Na, Ni, Sc, Si, Ti and V), selected from two moving groups, covering the metallicity range of -0.6 < [Fe/H] < 0.2, based on high-resolution spectra. Most of the elemental abundances show similar trends as in previous studies, except for Al, Na and Ba, which are seriously affected by evolution. The abundance ratios of [Na/Mg] increase smoothly with higher [Mg/H], and those of [Al/Mg] decrease slightly with increasing [Mg/H]. The abundance ratios of [Mg/Ba] show a distinction between these two moving groups, which is mainly induced by chemical evolution and also partly by kinematic effects. The inhomogeneous metallicity of each star from the moving groups demonstrates that these stars had different chemical origins before they were kinematically aggregated. This favours a dynamical resonant theory.

Liu, F.; Chen, Y. Q.; Zhao, G.; Han, I.; Lee, B. C.; Kim, K. M.; Zhao, Z. S.

2012-06-01

139

Regulating continent growth and composition by chemical weathering  

USGS Publications Warehouse

Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical weathering followed by subduction recycling are possible solutions, but the relative magnitudes of each process have never been quantitatively constrained because of the lack of appropriate data. Here, we show that the relative contributions of these processes can be obtained by simultaneous examination of Mg and Li (an analog for Mg) on the regional and global scales in arcs, delaminated lower crust, and river waters. At least 20% of Mg is lost from continents by weathering, which translates into >20% of continental mass lost by weathering (40% by delamination). Chemical weathering leaves behind a more Si-rich and Mg-poor crust, which is less dense and hence decreases the probability of crustal recycling by subduction. Net continental growth is thus modulated by chemical weathering and likely influenced by secular changes in weathering mechanisms. ?? 2008 by The National Academy of Sciences of the USA.

Lee, C. -T. A.; Morton, D. M.; Little, M. G.; Kistler, R.; Horodyskyj, U. N.; Leeman, W. P.; Agranier, A.

2008-01-01

140

Fog water chemical composition in different geographic regions of Poland  

NASA Astrophysics Data System (ADS)

The fog water samples were collected with the use of both passive and active fog collectors during 2005-2006 at 3 sites: lowland in northern Poland (Borucino; 186 m a.s.l.), valley basin in southern Poland (Zakopane; 911 m a.s.l.) and mountain top (Szrenica Mt.; 1330 m a.s.l.) in south-western Poland. For all daily samples (Borucino—25; Zakopane—4 and Szrenica—155), electric conductivity, pH, and concentrations of some anions: Cl -, F -, Br -, NO 2-, NO 3-, SO 42-, PO 43-and cations: NH 4+, Ca 2+, K +, Na + and Mg 2+ were measured. The selected ions were determined using ion suppressed chromatography (IC). Fog consists of a specific type of atmospheric phenomena. Results obtained on the basis of analysis of suitable fog samples can be treated as a source of valuable information on the chemistry of the atmosphere. Statistical analysis revealed significant differences depending on region, altitude, local morphology and, last but not least, fog origin. A distinct contrast is evident in the concentration and chemical composition between lowland radiation fog (represents lower layers of the atmosphere which are more influenced by continental emissions) versus orographic slope fog represented by a summit station, Mt Szrenica. It is partly induced by a distinction in weather conditions favouring fog existence, height of fog formation and its microphysical parameters. Acidity was associated with high concentrations of excess sulphate and nitrate in the fog water samples. Ammonium and calcium concentrations represent the most important neutralizing inputs. Collected cloud water at Szrenica Mt. includes solute contributions from emission sources located at much larger upwind distances. The fact that 95% of fog/cloud deposition is concentrated during SW-W-NW-N-NE, atmospheric circulation exerts an influence on the environmental quality of montane forests in the Sudety Mts. At numerous conspicuous convex landforms, where fog/cloud deposition becomes at least as important as wet deposition via atmospheric precipitation, a distinct difference in the health of coniferous forests is clearly visible, with the areas of the NW aspect being the worst affected, contrary to SE slopes with relatively healthy forest stands.

B?a?, Marek; Polkowska, ?aneta; Sobik, Mieczys?aw; Klimaszewska, Kamila; Nowi?ski, Kamil; Namie?nik, Jacek

2010-03-01

141

Chemical composition of the haze in Malaysia 2005  

NASA Astrophysics Data System (ADS)

A study of the chemical composition of the haze was conducted in two areas: Klang Valley and Malacca in Peninsular Malaysia, from July to September of 2005. The data is based on the reports of the air quality monitoring for particulate matter (PM10), pH of rainwater, anions (NO3?, SO42?, Cl?), cations (NH4+, Na2+, Ca2+, K+, Mg2+), heavy metals (Fe, Zn, Pb, Mn, Cu, Ni) and a meteorology parameter, the wind speed. The monthly concentrations of PM10 for the Klang Valley ranged from 35.90 to 104.46 ?g m?3 whilst in Malacca the concentration ranged from 35.80 to 54.30 ?g m?3 which was over the permitted level of 50 ?g m?3 for the time period of a month as stipulated by the Department of Environment Malaysia (DOE). The pH of rainwater collected in the Klang Valley ranged from 4.26 ± 0.12 to 5.45 ± 0.58, while in Malacca the pH varied from 4.35 ± 0.20 to 5.43 ± 0.12. The mean concentrations for NO3-, SO42-, Cl-, NH4+, Ca2+, Na2+, K+, Mg2+ for three months in the Klang Valley were 46.40 ± 11.16 ?eq L?1, 34.84 ± 9.82 ?eq L?1, 12.34 ± 4.13 ?eq L?1, 29.28 ± 11.02 ?eq L?1, 8.92 ± 0.88 ?eq L?1, 8.18 ± 1.00 ?eq L?1, 2.08 ± 0.34 ?eq L?1, 1.38 ± 0.24 ?eq L?1, respectively, whilst in Malacca, the mean concentrations were 24.46 ± 6.99 ?eq L?1, 28.4 ± 7.24 ?eq L?1, 27.32 ± 7.36 ?eq L?1, 30.92 ± 1.26 ?eq L?1, 4.10 ± 2.56 ?eq L?1, 21.44 ± 7.54 ?eq L?1, 3.18 ± 1.82 ?eq L?1 and 1.54 ± 1.66 ?eq L?1, respectively. These values were lower than the non haze period (January to March and April to June) except for the Cl- ion which recorded the highest anion in Malacca. However, the mean values were similar for the period from October to December. The mean concentrations of metals showed that Cu > Ni, whilst in Malacca, in descending order, were Fe > Zn > Cu > Mn > Pb > Ni.

Norela, S.; Saidah, M. S.; Mahmud, M.

2013-10-01

142

Variation in Miscanthus chemical composition and implications for conversion by pyrolysis and thermo-chemical bio-refining for fuels and chemicals.  

PubMed

Different species and genotypes of Miscanthus were analysed to determine the influence of genotypic variation and harvest time on cell wall composition and the products which may be refined via pyrolysis. Wet chemical, thermo-gravimetric (TGA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) methods were used to identify the main pyrolysis products and determine the extent to which genotypic differences in cell wall composition influence the range and yield of pyrolysis products. Significant genotypic variation in composition was identified between species and genotypes, and a clear relationship was observed between the biomass composition, yields of pyrolysis products, and the composition of the volatile fraction. Results indicated that genotypes other than the commercially cultivated Miscanthus x giganteus may have greater potential for use in bio-refining of fuels and chemicals and several genotypes were identified as excellent candidates for the generation of genetic mapping families and the breeding of new genotypes with improved conversion quality characteristics. PMID:21035327

Hodgson, E M; Nowakowski, D J; Shield, I; Riche, A; Bridgwater, A V; Clifton-Brown, J C; Donnison, I S

2011-02-01

143

The Effects of Blockiness on the Chemical Composition Distribution of Partially Functionalized Polystyrene  

NASA Astrophysics Data System (ADS)

Monodisperse polystyrene has been functionalized chemically to make random copolymers with controlled sequence distribution of the unmodified and modified styrene segments. The sequence blockiness of the resulting random copolymers can be controlled via the temperature of reaction, with a high temperature reaction resulting in a ``truly random'' copolymer, and a low temperature resulting in a ``random blocky'' copolymer. Interaction chromatography has been employed to estimate the chemical composition distribution of these partially functionalized polystyrenes. Two different chemical systems will be discussed; i.e., the brominated and borylated polystyrene systems. The results of our analysis reveal that the chemical composition distribution of ``random blocky'' copolymers is narrower than that of the corresponding ``truly random'' copolymers. The chemical composition of the two systems will be compared directly, and the influence of ``chain conformation inversion'' will be discussed.

Powers, Wayne; Genzer, Jan; Ryu, Chang Y.

2012-02-01

144

Chemical composition and emission sources of South Asian fine particulate matter estimated from satellite observations and a chemical transport model  

NASA Astrophysics Data System (ADS)

Epidemiologic and health impact studies are inhibited by the paucity of long-term measurements of the chemical composition of fine particulate matter, especially over the rapidly developing South Asian region. We applied a novel approach of collecting information from satellite observations and chemical transport model simulations to estimate the chemical composition and emission sources of long-term average ground-level PM2.5. We developed speciated PM2.5 concentrations and emission sources at a spatial resolution of approximately 10x10 km2 for 2004-2008 from aerosol optical depth measured from satellite instruments (MODIS and MISR), and coincident aerosol vertical profile and composition information from a global chemical transport model (GEOS-Chem). Evaluation of the dataset with North American in situ measurements indicated a significant spatial agreement. In situ measurements agreed better with the satellite-based product than the GEOS-Chem simulation. We found that South Asian population-weighted concentrations are dominated by secondary inorganic species (14.3 ug/m3), mineral dust (7.8 ug/m3), and particulate organic matter (7.4 ug/m3) components. Secondary inorganic aerosol concentrations exceeded 30 ug/m3 over the Indo-Gangetic Plain. The population-weighted mean uncertainty (1 SD) is 2.9 ug/m3 for secondary inorganic, 4.7 ug/m3 for mineral dust, and 3.0 ug/m3 for particulate organic matter, as estimated from uncertainty in aerosol optical depth, accuracy of the simulated aerosol vertical profile and speciation, and sampling.

Philip, S.; Martin, R. V.; van Donkelaar, A.; Wang, Y.; CHEN, D.; Zhang, L.

2012-12-01

145

The Chemical Composition and Evolution of Giant Molecular Cloud Cores: A Comparison of Observation and Theory  

Microsoft Academic Search

We present the results of an observational and theoretical study of the chemical composition and evolution of three giant cloud cores in Orion A, M17, and Cepheus A. This study is the culmination of a chemical survey of 32 transitions of 20 different molecules and isotopic variants in these cloud cores. Using these data, combined with observationally derived physical conditions,

Edwin A. Bergin; Paul F. Goldsmith; Ronald L. Snell; William D. Langer

1997-01-01

146

The effect of chemical stress on the polypeptide composition of the intercellular fluid of barley leaves  

Microsoft Academic Search

The effect of chemical stress on the polypeptide composition of the intercellular fluid of barley (Hordeum vulgare L.) and tomato (Lycopersicon esculentum Mill.) leaves has been studied. In some dicotyledonous plant species, including tomato, exposure to chemical stress leads to the denovo synthesis of intercellular proteins known as pathogenesis-related proteins which have been implicated to be part of a defence

Ruth Fischer; Susanna Behnke; Klaus Apel

1989-01-01

147

Rapid computation of chemical equilibrium composition - An application to hydrocarbon combustion  

NASA Technical Reports Server (NTRS)

A scheme for rapidly computing the chemical equilibrium composition of hydrocarbon combustion products is derived. A set of ten governing equations is reduced to a single equation that is solved by the Newton iteration method. Computation speeds are approximately 80 times faster than the often used free-energy minimization method. The general approach also has application to many other chemical systems.

Erickson, W. D.; Prabhu, R. K.

1986-01-01

148

The chemical composition of subducting sediment and its consequences for the crust and mantle  

Microsoft Academic Search

Subducted sediments play an important role in arc magmatism and crust–mantle recycling. Models of continental growth, continental composition, convergent margin magmatism and mantle heterogeneity all require a better understanding of the mass and chemical fluxes associated with subducting sediments. We have evaluated subducting sediments on a global basis in order to better define their chemical systematics and to determine both

Terry Plank; Charles H. Langmuir

1998-01-01

149

Dependence of the burning rate of a composite propellant on the chemical structure of the fuel  

Microsoft Academic Search

The question of the relationship between burning rate and chemical structure has received almost no attention, although there are qualitative indications that the burning does depend on the chemical structure of the fuel [2]. We have investigated the burning rates of composite propellants based on ammonium perchlorate (AP) and fuels containing various functional groupings. The calorific value has been experimentally

L. D. Romodanova; V. I. Pepekin; A. Ya. Apin; P. F. Pokhil

1970-01-01

150

Chemical composition of boundary layer aerosol over the Atlantic Ocean and at an Antarctic site  

Microsoft Academic Search

Aerosol chemical composition was measured over the Atlantic Ocean in November-December 1999 and at the Finnish Antarctic research station Aboa in January 2000. The concentrations of all anthropogenic aerosol compounds decreased clearly from north to south. An anthropogenic influence was still evident in the middle of the tropical South Atlantic, background values were reached south of Cape Town. Chemical mass

A. Virkkula; K. Teinilä; R. Hillamo; V.-M. Kerminen; S. Saarikoski; M. Aurela; J. Viidanoja; J. Paatero; I. K. Koponen; M. Kulmala

2006-01-01

151

Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition  

Microsoft Academic Search

Sorption potential of waste short hemp fibers for Pb2+, Cd2+ and Zn2+ ions from aqueous media was explored. In order to assess the influence of hemp fiber chemical composition on their heavy metals sorption potential, lignin and hemicelluloses were removed selectively by chemical modification. The degree of fiber swelling and water retention value were determined in order to evaluate the

Biljana Pejic; Marija Vukcevic; Mirjana Kostic; Petar Skundric

2009-01-01

152

Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke.  

PubMed

A new-technology cigarette has been developed. While the new cigarette burns some tobacco, it does not use tobacco as the fuel to sustain combustion and provide heat to the cigarette. Rather, the new cigarette primarily heats tobacco thereby reducing products of smoke formation mechanisms such as tobacco combustion, tobacco pyrolysis and pyrosynthesis. The mainstream smoke composition from a cigarette based on the new design (TOB-HT) has been characterized in comparative chemical testing with two reference cigarettes using the FTC puffing regimen. Thermal properties, UV absorption characteristics, elemental composition and materials balance studies all suggest a simplified smoke aerosol. Twenty-five smoke constituents ("target compounds") identified by the scientific community as compounds that may contribute to the diseases statistically associated with smoking have also been measured. Mainstream smoke concentrations of most target compounds are significantly lower with the TOB-HT cigarette when compared with reference cigarettes in the ultra-light "tar" and light "tar" categories. Taken together, chemical analysis results suggest simplified TOB-HT smoke chemistry with marked reductions in specific chemicals reported to be biologically active. PMID:9609390

Borgerding, M F; Bodnar, J A; Chung, H L; Mangan, P P; Morrison, C C; Risner, C H; Rogers, J C; Simmons, D F; Uhrig, M S; Wendelboe, F N; Wingate, D E; Winkler, L S

1998-03-01

153

Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke.  

PubMed

A new-technology cigarette has been developed. While the new cigarette burns some tobacco, it does not use tobacco as the fuel to sustain combustion and provide heat to the cigarette. Rather, the new cigarette primarily heats tobacco thereby reducing products of smoke formation mechanisms such as tobacco combustion, tobacco pyrolysis and pyrosynthesis. The mainstream smoke composition from a cigarette based on the new design (TOB-HT) has been characterized in comparative chemical testing with two reference cigarettes using the FTC puffing regimen. Thermal properties, UV absorption characteristics, elemental composition and materials balance studies all suggest a simplified smoke aerosol. Twenty-five smoke constituents ("target compounds") identified by the scientific community as compounds that may contribute to the diseases statistically associated with smoking have also been measured. Mainstream smoke concentrations of most target compounds are significantly lower with the TOB-HT cigarette when compared with reference cigarettes in the ultra-light "tar" and light "tar" categories. Taken together, chemical analysis results suggest simplified TOB-HT smoke chemistry with marked reductions in specific chemicals reported to be biologically active. PMID:9687969

Borgerding, M F; Bodnar, J A; Chung, H L; Mangan, P P; Morrison, C C; Risner, C H; Rogers, J C; Simmons, D F; Uhrig, M S; Wendelboe, F N; Wingate, D E; Winkler, L S

1998-07-01

154

Chemical Threats  

MedlinePLUS

Chemical agents are poisonous vapors, aerosols, liquids and solids that have toxic effects on people, animals or plants. They ... hazard to people and the environment. Some chemical agents may be odorless and tasteless. They can have ...

155

Home Chemicals  

NSDL National Science Digital Library

This lesson provides an introduction to the occurrence and possible risks of household chemical products. Topics include some basic chemistry (how elements combine to form compounds), how chemicals are classified, and the idea of natural, as opposed to synthetic, chemicals. The lesson includes an activity in which students take an inventory of chemical products in their homes and research the possible hazards of some of them using an online resource developed by the National Institutes of Health (NIH).

Fox, Chris

156

Chemical Biology\\/ Chemical Genetics\\/ Chemical Genomics: Importance of Chemical Library  

Microsoft Academic Search

A new field of science, chemical biology\\/ chemical genetics\\/ chemical genomics (cb\\/cg\\/cg) has emerged since the late 1990's, especially in the United States. The NIH Roadmap agenda, Molecular Libraries Screening Center Network (MLSCN), became a drive force to push cb\\/cg\\/cg forward. Cb\\/cg\\/cg studies consist of three methodologies, chemical libraries with small molecules, high-throughput screenings, and computational databases. In this review,

Fumihiko Kugawa; Masaru Watanabe; Fuyuhiko Tamanoi

2007-01-01

157

Improved fiber-reinforced SiC composites fabricated by chemical vapor infiltration  

SciTech Connect

Fabrication of fiber-reinforced composites by a patented chemical vapor infiltration process has continued. Modifications to the process used for infiltration of unidirectional preforms resulted in more uniform matrix deposition throughout the preform and improved mechanical properties of the composites. Infiltration of improved cloth preforms containing more uniform porosity resulted in composites with fewer and smaller voids.

Stinton, D.P.; Caputo, A.J.; Lowden, R.A.; Besmann, T.M.

1986-01-01

158

Preparation and Characterization of Chemically Synthesized Hybrid Composites for Bone Tissue Regeneration  

NASA Astrophysics Data System (ADS)

The aim of this study concerns the development of bioresorbable composite materials for bone repair and regeneration. Hydroxyapatite loaded composites were synthesized by a colloidal non-aqueous chemical precipitation technique at room temperature. This study describes the synthesis and characterization of HA/PCL composite material, in order to verify the interaction between the ceramic and the polymer phases by a morphological investigation.

Raucci, M. G.; Guarino, V.; Ambrosio, L.

2008-08-01

159

Salinity Variations and Chemical Compositions of Waters in the Frio Formation, Texas Gulf Coast. Annual Report.  

National Technical Information Service (NTIS)

Waters produced from sandstone reservoirs of the deep Frio Formation exhibit spatial variations in chemical composition that roughly coincide with the major tectonic elements (Houston and Rio Grande Embayments, San Marcos Arch) and corresponding depositio...

R. A. Morton C. M. Garrett J. S. Posey J. H. Han L. A. Jirik

1981-01-01

160

Chemical compositions of peridotite xenoliths from Vitim, SE Siberia  

NASA Astrophysics Data System (ADS)

Located 200-250 km east of Lake Baikal in SE Siberia, the Cenozoic Vitim volcanic field comprises mantle xenolith-bearing lava flows in several localities including those sampled in this study — the Bulykhta river, Kandidushka volcano and a picrobasalt quarry to the north of the Yaksha II volcano. The majority of samples are hydrous mineral-free, garnet-, spinel-, or garnet-spinel-bearing lherzolites, with a protogranular texture and to a lesser extent porphyroclastic texture. Kink bands and fluid inclusions are commonly seen in the olivines and "spongy" rims in clinopyroxenes. Employing the two-pyroxene thermometer and the Al-in-opx barometer of Brey and Köhler [1] yields equilibration temperatures of 1050-1250 OC and pressures of 20-28 kbar. Cores of primary clinopyroxenes have Al2O3 between 5.2 and 6.9 wt.% and olivines have a limited range of Fo contents between 0.89 and 0.91. The latter does not correlate with Cr# in spinel, which would otherwise be expected for residual mantle. These mineral chemical features are typical of subcontinental lithospheric mantle (SCLM) which does not experience substantial degrees of partial melting. In accord with this conclusion are the whole-rock Sr-Nd isotopic data of the studied Vitim peridotites (143Nd/144Nd = 0.51288-0.51310 and 87Sr/86Sr = 0.7034-0.7056) which approach the composition of bulk silicate earth (BSE). By contrast, the whole-rock REE patterns of the Vitim samples are not consistent with a simple fertile SCLM model. Their HREE abundances are depleted relative to the primitive mantle (YbN = ~0.2 to ~0.5; primitive mantle normalizing values of [2]), and LREEs in most samples are enriched (LaN = 4.0-5.1, except one sample of LaN = 0.5), with (La/Yb)N between 1 and 22, suggesting that melt extraction has taken place for these rocks, followed by incompatible element enrichment by metasomatism. Whereas the discrepancy between (H)REE and major elements may be reconciled with relatively small degrees of partial melting, that between the REE and Sr-Nd isotope systematic is less certain. The latter may be reasonably accounted for by one of these scenarios: (1) the depletion and subsequent metasomatic event occurred on long-standing fertile, BSE-like SCLM shortly before the xenoliths were carried to the surface; (2) the metasomatic enrichment occurred long time ago such that there are sufficiently high Rb/Sr and low Sm/Nd to give rise to high 87Sr/86Sr and low 143Nd/144Nd respectively; or (3) irrelevant to the time of depletion and metasomatism, the Sr-Nd isotopic signature of the original Vitim SCLM has been overprinted by that of isotopically "enriched" agents such as metasomatic fluids/melts. [1] Brey, G.P., Köhler, T. (1990) J. Petrol. 31: 1353-78 [2] McDonough, W.F., Sun, S.-S. (1995) Chem. Geol. 120: 223-53

Chien, Y.; Wang, K. S.; Chung, S.; Ma, G. S.; Iizuka, Y.; Kuzmin, M.; Vorontsov, A.; Ivanov, A.

2012-12-01

161

Atmospheric aerosol over Vermont: chemical composition and sources.  

PubMed

Aerosol chemical composition data for PM2.5 samples collected during the period from 1988 to 1995 at Underhill, VT, were analyzed. Sulfur and black carbon mass concentrations ranged from 0.01 to 6.5 microg m(-3) and from 0.05 to 2.2 microg m(-3), respectively, while the total fine aerosol mass concentration ranged from 0.2 to 51.1 microg m(-3). Seasonal variations with maxima during the summer and minima in winter/spring were observed for sulfur and the fine mass concentrations. No annual pattern was observed for black carbon. Seasonal variations for most of the other anthropogenic species had maxima in winter and spring and minima in the summer. A factor analysis method, positive matrix factorization (PMF), utilizing error estimates of the data to provide optimum data point scaling was used to obtain information about possible sources of the aerosol. An 11-factor solution was obtained. The six sources representing wood burning, coal and oil combustion, coal combustion emissions plus photochemical sulfate production, metal production plus municipal waste incineration, and emissions from motor vehicles were identified. Emissions from smelting of nonferrous metal ores, arsenic smelting, and soil particles and particles with high concentrations of Na were also identified by PMF. Potential source contribution function (PSCF) analysis combines the aerosol data with the air parcel backward trajectories. PSCF was applied to identify possible source areas and pathways that give rise to the observed high particulate mass concentrations from these 11 sources. The CAPITA Monte Carlo trajectory model was used to obtain 10 sets of 5-day air parcel back trajectories arriving every 2 h for the 7-yr period from 1988 to 1995. The PSCF plot for the black carbon factor shows high probabilities in the area surrounding the sampling site, indicating a strong local influence from residential wood combustion in northern New England and southwestern Quebec. Similar large potential source areas in the midwestern United States were identified for the two coal combustion factors. The midwestern United States was also identified as the source region for the Zn-Pb factor. The oil combustion factor was associated with the east coast of the United States. The results for the Pb-Mn factor suggests high probability over the nearby Montreal urban area and the areas in the midwestern United States. The windblown dust emissions from the areas to the north are significant contributors for the soil factor. Canadian Ni smelters are the main sources for the As factor, although there is some contribution from coal-fired power plants to the south and west of Underhill, VT. It is concluded that the combination of the two receptor modeling methods, PMF and PSCF, provides an effective way in identifying atmospheric aerosol sources and their likely locations. Emissions from different anthropogenic activities as well as secondary aerosol production are the main sources of aerosol measured in Vermont. Fuel combustion, local wood smoke, municipal waste incineration, and the secondary sulfate production collectively accounted for about 87% of the fine mass concentrations measured in Vermont. PMID:11770762

Polissar, A V; Hopke, P K; Poirot, R L

2001-12-01

162

Chemical Composition of Atmospheric Aerosols in Iowa City  

NASA Astrophysics Data System (ADS)

In this study, the seasonal and spatial variability of chemical components in atmospheric PM2.5 were investigated in Iowa City, Iowa for the first time. Daily PM samples were collected from 25 August to 10 November 2011 at two sites in Iowa City (West and East) that were separated by approximately four miles. During this time, daily average PM2.5 mass concentrations ranged from 3 - 26 ?g m-3, within attainment of EPA National Ambient Air Quality Standard of 35 ?g m-3. The average PM2.5 concentration was 11.2×4.9 ?g m-3 (arithmetic mean × one standard deviation for n = 72). Carbonaceous aerosol (elemental carbon and organic matter) was the dominant component of PM2.5, contributing 40% of PM2.5 mass. Another 30% was due to water soluble inorganic ions (SO42-, NO3-, Cl-, Na+, NH4+, K+, Mg2+, Ca2+) with major contributions from SO42- (13%), NO3- (6%), NH4+ (6%) and Ca2+ (3%). Among the inorganic ions, SO42- exhibited the highest individual ion concentration at both sites with an average concentration of 1.5×1.2 ?g m-3 at West Site and 1.5×1.3 ?g m-3 at East Site. The average NO3- concentrations for this period were 0.5×0.4 ?g m-3 and 0.7×0.5 ?g m-3 at West and East Sites, respectively. Comparison of aerosol composition data from the two sites indicated that concentrations of SO42-, NO3-, NH4+ and organic carbon were not statistically different at the 95% confidence interval, indicating that these species were primarily influenced by regional atmospheric processes. Meanwhile, Ca2+ and elemental carbon concentrations were statistically different across the two study sites, indicating the influence of local PM sources. Unlike other ions, Ca2+ concentrations were significantly elevated at both sites in October, during the agricultural harvest, showing that re-suspended soil dust is a temporally-variable source of fine particles that peaks during the agricultural harvest season. Several episodes of elevated PM2.5 occurred in late August to early October, with elevated levels of SO42-, NH4+, and organic carbon; these episodes occurred during periods of high temperature, dry atmospheric conditions, and southerly air masses that contributed to high secondary aerosol concentrations. NO3- concentrations increased from August to November, consistent with enhanced formation of NH4NO3 under colder temperatures. With the majority of PM2.5 attributed to secondary sources, we conclude that significant reductions in PM2.5 concentrations in Iowa City will require addressing secondary aerosol sources on a regional scale.

Jayarathne, T. S.; Stone, E.

2013-12-01

163

Chemical sensor  

NASA Technical Reports Server (NTRS)

A sensor for detecting a chemical substance includes an insertion element having a structure which enables insertion of the chemical substance with a resulting change in the bulk electrical characteristics of the insertion element under conditions sufficient to permit effective insertion; the change in the bulk electrical characteristics of the insertion element is detected as an indication of the presence of the chemical substance.

Rauh, R. David (Inventor)

1990-01-01

164

Chemical composition of fresh snowfalls at Palmer Station, Antarctica  

NASA Astrophysics Data System (ADS)

A first time investigation was performed to establish a chemical baseline for snowfall at Palmer Station Antarctica (64°46'S, 64°05'W) since there was no such record. A chemical baseline for snow could be use to validate climate change studies based on ice core analyses. The snow samples contained (from high to low mass concentration) total organic carbon, chloride, inorganic carbon, sodium, sulfate, magnesium, calcium, potassium, fluoride, ammonium, and nitrate, excluding hydrogen and hydroxide. The pH of these samples ranged between 4.0-6.2. The relatively low nitrate and relatively high sulfate concentrations found in our samples are consistent with the results of other studies for this region of Antarctica. The ions and pH do not appear to favor a particular wind direction during this period. The total deposition of sulfate and flouride via snowfall between 10 January and 10 February is conservatively estimated to be 4.78 and 1.3 kg km -2, respectively.

DeFelice, T. P.

165

Chemical separations using shell and tube composite polyphophazene membranes  

SciTech Connect

Several applications of modular shell and tube polyphosphazene coated membrane units are reported in this paper. These modules were used to measure the mixed-gas separation properties of poly(bis(phenoxy)phosphazene) based polymers on a larger scale. Transport behavior was determined using the variable volume technique. The test gas mixture was SO{sub 2}/N{sub 2} at temperatures between 80{degrees}C and 270{degrees}C. Transport of these gases was found to be a sorption controlled process. Several organic-aqueous and organic-organic separations have been performed using the polyphophazene coated shell and tube modules. The separations include: methylene chloride/water, acetic acid/water, isopropyl alcohol/water, glycerol/water, and hexane/soy oil. The membranes were prepared using slip casting techniques. The results of these studies show that polyphosphazene membranes can effectively be used to separate acid gases and organic chemicals from various waste streams in harsh, chemically aggressive environments.

Peterson, E.S.; Stone, M.L.; Orme, C.J. [Idaho National Engineering Laboratory, Idaho Falls, ID (United States)

1995-04-01

166

Chemical composition and biological activity of Citrus jambhiri Lush.  

PubMed

The fresh peel of Citrus jambhiri was extracted with aqueous methanol and the residue was fractionated using light petroleum, chloroform and ethyl acetate. The constituents of the extracts were separated by column chromatography employing solvents of different polarity. The chemical structure of the isolated compounds was then identified by MS and NMR. Column chromatography of the petroleum fraction resulted in the isolation of nobiletin, 5-O-demethylnobiletin, tangeretin, 5-hydroxy-3,6,7,8,3',4'-hexamethoxyflavone, 3,5,6,7,8,3',4'-heptamethoxyflavone, and a mixture of ?-sitosterol and stigmasterol. The chloroform fraction afforded 6-demethoxynobiletin, 5,4'-dihydroxy-6,7,8,3'-tetramethoxyflavone, limonin and nomilin. The flavonoid glycosides naringin, hesperidin and neohesperidin were isolated from the ethyl acetate fraction. The chemical structure of the isolated compounds was established by MS and NMR (APT, COSY, HSQC, HMBC, and NOESY). LC-ESI-MS analysis of the ethyl acetate fraction afforded eight flavonoid glycosides, while the dichloromethane fraction of the defatted seeds contained seven limonoid aglycones. The chloroform fraction exerted the strongest DPPH(?) free radical scavenging activity in comparison to other fractions. The petroleum fraction showed a significant inhibition of lipoxygenase indicating an anti-inflammatory action (IC(50) 29±1?g/mL). Some of the isolated polymethoxyflavones exhibited strong cytotoxicity against COS7, HeLa and Caco-2 cell lines. PMID:23140678

Hamdan, Dalia; El-Readi, Mahmoud Zaki; Tahrani, Ahmad; Herrmann, Florian; Kaufmann, Dorothea; Farrag, Nawal; El-Shazly, Assem; Wink, Michael

2011-07-15

167

Concentration and chemical composition of PM 2.5 in Shanghai for a 1-year period  

Microsoft Academic Search

Weekly PM2.5 samples were collected in Shanghai, China at two sites, Tongji University and Hainan Road. Sampling started in March 1999 and was conducted for 1 year. The ambient mass concentration and chemical composition of the PM2.5 were determined. Chemical analyses included elemental composition, water-soluble ions, and organic and elemental carbon. Weekly PM2.5 mass concentrations ranged from 21 to 147?g\\/m3,

Boming Ye; Xueli Ji; Haizhen Yang; Xiaohong Yao; Chak K. Chan; Steven H. Cadle; Tai Chan; Patricia A. Mulawa

2003-01-01

168

Precipitation of niobium carbonitrides in ferrite: chemical composition measurements and thermodynamic modelling  

Microsoft Academic Search

High-resolution transmission electron microscopy and electron-energy loss spectroscopy have been used to characterize the structure and chemical composition of niobium carbonitrides in the ferrite of a Fe–Nb–C–N model alloy at different precipitation stages. Experiments seem to indicate the coexistence of two types of precipitates: pure niobium nitrides and mixed sub-stoichiometric niobium carbonitrides. In order to understand the chemical composition of

M. Perez; E. Courtois; D. Acevedo; T. Epicier; P. Maugis

2007-01-01

169

The Chemical Equilibrium Problem.  

National Technical Information Service (NTIS)

It has long been known that the problem of determining the equilibrium composition of a solution of chemically reacting species could be formulated as a constrained minimum problem. Previous methods for solving the chemical equilibrium problem in this for...

J. H. Bigelow

1968-01-01

170

A rapid method for the computation of equilibrium chemical composition of air to 15000 K  

NASA Technical Reports Server (NTRS)

A rapid computational method has been developed to determine the chemical composition of equilibrium air to 15000 K. Eleven chemically reacting species, i.e., O2, N2, O, NO, N, NO+, e-, N+, O+, Ar, and Ar+ are included. The method involves combining algebraically seven nonlinear equilibrium equations and four linear elemental mass balance and charge neutrality equations. Computational speeds for determining the equilibrium chemical composition are significantly faster than the often used free energy minimization procedure. Data are also included from which the thermodynamic properties of air can be computed. A listing of the computer program together with a set of sample results are included.

Prabhu, Ramadas K.; Erickson, Wayne D.

1988-01-01

171

Chemical engineer  

NSDL National Science Digital Library

What do chemical engineers actually do? This is the introductory page for a set of materials about chemical engineering as a career. Here the job of a chemical engineer is defined and described. Chemical engineers often work with industrial manufacturing processes that involve a mix of chemistry and engineering. In the rest of the resource, students can examine a specialized job title associated with chemical engineering: process engineer. Students can view a five-minute video clip of the process engineer as he works in a fertilizer plant making ammonia and urea. Students follow the engineer around the plant as he checks pressure in chemical lines. Students get a glimpse of the inside of a furnace during the chemical-making process. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2002-01-01

172

Software for analysis of chemical mixtures--composition, occurrence, distribution, and possible toxicity  

USGS Publications Warehouse

The composition, occurrence, distribution, and possible toxicity of chemical mixtures in the environment are research concerns of the U.S. Geological Survey and others. The presence of specific chemical mixtures may serve as indicators of natural phenomena or human-caused events. Chemical mixtures may also have ecological, industrial, geochemical, or toxicological effects. Chemical-mixture occurrences vary by analyte composition and concentration. Four related computer programs have been developed by the National Water-Quality Assessment Program of the U.S. Geological Survey for research of chemical-mixture compositions, occurrences, distributions, and possible toxicities. The compositions and occurrences are identified for the user-supplied data, and therefore the resultant counts are constrained by the user’s choices for the selection of chemicals, reporting limits for the analytical methods, spatial coverage, and time span for the data supplied. The distribution of chemical mixtures may be spatial, temporal, and (or) related to some other variable, such as chemical usage. Possible toxicities optionally are estimated from user-supplied benchmark data. The software for the analysis of chemical mixtures described in this report is designed to work with chemical-analysis data files retrieved from the U.S. Geological Survey National Water Information System but can also be used with appropriately formatted data from other sources. Installation and usage of the mixture software are documented. This mixture software was designed to function with minimal changes on a variety of computer-operating systems. To obtain the software described herein and other U.S. Geological Survey software, visit http://water.usgs.gov/software/.

Scott, Jonathon C.; Skach, Kenneth A.; Toccalino, Patricia L.

2013-01-01

173

The chemical composition of wool. XV. The cell membrane couplex.  

PubMed

The cell membrane complex of wool has been examined by electron microscopy of stained cross sections after immersion of the wool in formic acid. The cell membrane complex of the cortex is considerably modified by the treatment, but that of the cuticle appears unchanged. Resistant membranes from cuticle cells, cortical cells and wool have been prepared by treatment with performic acid-ammonia. Amino acid analyses show that the resistant membranes from the cuticle contain citrulline but those from cortical cells do not. It is concluded that the cell membrane complex of the cuticle differs from that of the cortex. Because of the high lysine content of the resistant membranes, their resistance to chemical attack, the hydrophobicity of epicuticle and the observation of a small amount of epsilon-(gamma-glutamyl)lysine, it is postulated that the resistant membranes may contain an appreciable amount of epsilon-(gamma-glutamyl)lysine cross links. PMID:60989

Peters, D E; Bradbury, J H

1976-03-01

174

Simplifying chemical kinetics intrinsic low-dimensional manifoldsin composition space  

Microsoft Academic Search

A general procedure for simplifying chemical kinetics is developed,\\u000d\\u000a\\u0009based on the dynamical systems approach. In contrast to conventional\\u000d\\u000a\\u0009reduced mechanisms no information is required concerning which reactions\\u000d\\u000a\\u0009are to be assumed to be in partial equilibrium nor which species\\u000d\\u000a\\u0009are assumed to be in steady state. The only “inputs” to the procedure\\u000d\\u000a\\u0009are the detailed kinetics mechanism and the

U. Maas; S. B. Pope

1992-01-01

175

Chemical composition of streams during low flow; Fairfax County, Virginia  

USGS Publications Warehouse

Water samples were collected and stream discharges were measured at 49 sites in Fairfax County, Virginia during a period of low flow in August 1977. In addition, pesticide and metal content of residue on stream-bottom sediments from several major streams in the county were analysed. Waters from the streams in Fairfax County have generally good chemical quality during low flow. One stream in Vienna, Virginia has a high sodium chloride content, suggesting an upstream discharge of salty water. Higher concentrations of dissolved, solids reflect both the effects of geology and urbanization. Streams draining Triassic rocks in the western section of the county are characterized by the greatest natural concentration of dissolved minerals in the water. The concentrations of pesticide and metal residue associated with bottom sediments suggest a low level of pollution in the streams. One site in western Fairfax County contained above-normal levels of polychlorinated biphenyls (PCB's) in the stream sediments.

Larson, J. D.

1978-01-01

176

Fine particulate chemical composition and light extinction at Meadview, AZ  

SciTech Connect

The concentration of fine particulate nitrate, sulfate, and carbonaceous material was measured for 12-hr daynight samples using diffusion denuder samplers during the Project Measurement of Haze and Visibility Effects (MOHAVE) July to August 1992 Summer Intensive study at Meadview, AZ, just west of Grand Canyon National Park. Organic material was measured by several techniques. Only the diffusion denuder method measured the semivolatile organic material. Fine particulate sulfate and nitrate (using denuder technology) determined by various groups agreed. Based on the various collocated measurements obtained during the Project MOHAVE study, the precision of the major fine particulate species was {+-} 0.6 {mu}g/m{sup 3} organic material, {+-} 0.3 {mu}g/m{sup 3} ammonium sulfate, and {+-} 0.07 {mu}g/m{sup 3} ammonium nitrate. Fine particulate organic material was the principal particulate contributor to light extinction during the study period, with fine particulate sulfate as the second most important contributor. Particle light extinction was dominated by sulfate and organic material during periods of lowest light extinction. Combination of the extinction data and chemical mass balance analysis of sulfur oxides sources in the region indicate that the major anthropogenic contributors to light extinction were from the Los Angeles, CA, and Las Vegas, NV, urban areas. Mohave Power Project associated secondary sulfate was a negligible contributor to light extinction. 49 refs., 12 figs., 7 tabs.

Delbert J. Eatough; Wenxuan Cui; Jeffery Hull; Robert J. Farber [Brigham Young University, Provo, UT (United States). Department of Chemistry and Biochemistry

2006-12-15

177

Brazilian red propolis--chemical composition and botanical origin.  

PubMed

Propolis contains resinous substances collected by honey bees from various plant sources and has been used as a traditional folk medicine since ca 300 BC. Nowadays, the use of evidence-based complementary and alternative medicine (CAM) is increasing rapidly and so is the use of propolis in order to treat or support the treatment of various diseases. Much attention has been focused on propolis from Populus sp. (Salicaceae) and Baccharis dracunculifolia (Asteracea), but scientific information about the numerous other types of propolis is still sparse. We gathered six samples of red propolis in five states of Northeastern Brazil. The beehives were located near woody perennial shrubs along the sea and river shores. The bees were observed to collect red resinous exudates on Dalbergia ecastophyllum (L) Taub. (Leguminosae) to make propolis. The flavonoids of propolis and red resinous exudates were investigated using reversed-phase high-performance liquid chromatography and reversed-phase high-performance thin-layer chromatography. We conclude that the botanical origin of the reddish propolis is D. ecastophyllum. In areas where this source (D. ecastophyllum) was scarce or missing, bees were collecting resinous material from other plants. Propolis, which contained the chemical constituents from the main botanical origin, showed higher antimicrobial activity. PMID:18955226

Daugsch, Andreas; Moraes, Cleber S; Fort, Patricia; Park, Yong K

2008-12-01

178

Chemical Composition of Two Exopolysaccharides from Bacillus thermoantarcticus  

PubMed Central

The thermophilic bacterium Bacillus thermoantarcticus produces two exocellular polysaccharides (EPS 1 and EPS 2), which can be obtained from the supernatant of liquid cultures by cold-ethanol precipitation, in yields as high as 400 mg liter(sup-1). The EPS fraction was produced with all substrates tested, although a higher yield was obtained with mannose as the carbon and energy source. The EPS content was proportional to the total biomass. On a weight basis, EPS 1 and EPS 2 represented about 27 and 71%, respectively, of the total carbohydrate fraction. EPS 1 is a sulfate heteropolysaccharide containing mannose and glucose in a relative molar proportion of 1.0 and 0.7, respectively. EPS 2 is a sulfate homopolysaccharide containing mannose as the major component. The absolute configurations of hexoses were shown to be d for both EPSs. Nuclear magnetic resonance spectra confirmed the presence of (alpha)-d-mannose and (beta)-d-glucose in EPS 1 and only (alpha)-d-mannose in EPS 2. In addition, (sup1)H nuclear magnetic resonance analysis and chemical analysis indicated the presence of pyruvic acid in EPS 2.

Manca, M. C.; Lama, L.; Improta, R.; Esposito, E.; Gambacorta, A.; Nicolaus, B.

1996-01-01

179

Chemical Bonds  

NSDL National Science Digital Library

Electrons are key to forming the two broad categories of chemical bonds: covalent and ionic. Atoms, which have a nucleus surrounded by electrons, are represented in several different ways. In the Chemical Bonds activity, students explore the different kinds of chemical bonds that can form, ranging from non-polar covalent to ionic. In the model depicted above students adjust the electronegativity of two atoms and see the effect it has on electron distribution and bond type.

Consortium, The C.

2011-12-11

180

Effect of chemical treatment on the structure and morphology of coir fiber composites  

NASA Astrophysics Data System (ADS)

Researchers have focused their attention on coir fiber, a waste product found abundant in nature having excellent properties. Coir fiber is treated with nitro compounds in order to change the fiber properties. In order to measure all effects on coir fiber composites due to chemical treatment various tools such as XRD and SEM are carried out. As a result of the chemical treatment change in the morphology of coir fiber has been found when compared with untreated coir fiber which is confirmed by SEM technique. XRD studies shows that coir fiber composites are crystalline in nature. The main objective of the present study is to make ecofriendly and cost effective coir fiber composites.

Khan, Alveera; Joshi, S.

2013-06-01

181

Energy Spectrum and Chemical Composition of Ultrahigh Energy Cosmic Rays from Semi-relativistic Hypernovae  

NASA Astrophysics Data System (ADS)

It has been suggested that hypernova remnants, with a substantial amount of energy in semi-relativistic ejecta, can accelerate intermediate mass or heavy nuclei to ultrahigh energies and provide a sufficient amount of energy in cosmic rays to account for the observed flux. We here calculate the expected energy spectrum and chemical composition of ultrahigh energy cosmic rays from such semi-relativistic hypernovae. With a chemical composition equal to that of the hypernova ejecta and a flat or hard spectrum for cosmic rays at the sources, the spectrum and composition of the propagated cosmic rays observed at the Earth can be compatible with the measurements by the Pierre Auger Observatory.

Liu, Ruo-Yu; Wang, Xiang-Yu

2012-02-01

182

ENERGY SPECTRUM AND CHEMICAL COMPOSITION OF ULTRAHIGH ENERGY COSMIC RAYS FROM SEMI-RELATIVISTIC HYPERNOVAE  

SciTech Connect

It has been suggested that hypernova remnants, with a substantial amount of energy in semi-relativistic ejecta, can accelerate intermediate mass or heavy nuclei to ultrahigh energies and provide a sufficient amount of energy in cosmic rays to account for the observed flux. We here calculate the expected energy spectrum and chemical composition of ultrahigh energy cosmic rays from such semi-relativistic hypernovae. With a chemical composition equal to that of the hypernova ejecta and a flat or hard spectrum for cosmic rays at the sources, the spectrum and composition of the propagated cosmic rays observed at the Earth can be compatible with the measurements by the Pierre Auger Observatory.

Liu Ruoyu; Wang Xiangyu [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

2012-02-10

183

Effect of Chemical Modification on the Mechanical and Electrical Properties of Banana Fiber Polyester Composites  

Microsoft Academic Search

Banana fiber obtained from the sheath of the banana plant, Musa sapientum, has been used in the preparation of composites with polyester matrix. The effect of fiber loading on the dielectric constant, volume resistivity, and dielectric loss factor of the composites were determined with special reference to the effect of frequency. The fibers were modified chemically in order to have

L. A. Pothan; C. N. George; M. Jacob; S. Thomas

2007-01-01

184

Chemical Composition and Antigenic Structure of Cell Walls of Corynebacterium, Mycobacterium, Nocardia, Actinomyces and Arthrobacter  

Microsoft Academic Search

14 comparison has been made between the chemical composition of the cell walls of strains from the genera Corynebucterizcm, Alycobacterium, Nocardia, Actiwmycrs and Arthrobacter, and the antigenic composition of the same cell-wall fractions as judged by an agglutination test. ,4 common antigenic component was identified in all those strains of' corynchacteria, mycohacteria and nocardias which have arabinose and galactose as

C. S. Cummins; E. Lopidon

1962-01-01

185

[Review on chemical composition and constituents of some important exotic fruits (author's transl)].  

PubMed

In this paper the chemical composition and the known constituents of mango, pomegranate, passion fruits, papaya, guava, feijoa, litchi, cherimoya and other Annona-species, japanese persimmone, acerola, prickly pears, naranjilla, tamarillo and cape-gooseberry are reviewed. The composition of avocado and kiwi is shortly refered. PMID:7023094

Herrmann, K

1981-01-01

186

Chemical composition and size distributions of coastal aerosols observed on the US East Coast  

Microsoft Academic Search

Characterization of coastal aerosols is important to the study of the atmospheric input of nutrients to the adjacent marine and the ocean ecosystems. Over a land–ocean transition zone, however, aerosol composition could be strongly modified by anthropogenic emissions and transport processes. This work focuses on examining aerosol properties, in particular chemical composition, particle-size distributions and iron (Fe) solubility, over the

Lili Xia; Yuan Gao

2010-01-01

187

Chemical Composition of Volatile Oils from Algerian Nigella sativa L. seeds  

Microsoft Academic Search

The chemical composition of the volatiles obtained from the fixed oils of Nigella sativa L. seeds growing in Algeria was investigated by GC and GC\\/MS analysis. Two solvents were studied for extracting the oils, hexane and isopropanol.The composition of N. sativa seeds varieties having four location origins in Algeria, were determined. Alcohols and ketones formed the main proportion using the

Farid Benkaci-Ali; Aoumeur Baaliouamer; Jean Paul Wathelet; Michel Marlier

2010-01-01

188

Regional background acidity and chemical composition of precipitation in Thailand  

NASA Astrophysics Data System (ADS)

In a joint Thai-Swedish project, within the framework of the IGAC/DEBITS project, precipitation has been collected for chemical analysis on a daily basis since mid-1991 at two sites in the countryside of Thailand. The quality assurance plan includes investigation of the effect of different sampling equipment (including wet-only collectors), sampling time and stability of samples collected in tropical conditions. Consistent results, unbiased by local conditions, have been obtained. The data show striking day-to-day fluctuations, reflecting changes in transport direction and an inhomogeneous distribution of sources. For days with little precipitation the concentration of the components ranges from low to high values while the range is smaller and concentration generally lower during days of high precipitation amount. Mean concentrations are similar at the two stations but the correlation between daily samples is low as can be expected for a distance between the stations of 500 km. A seasonal variation could not be significantly determined. The best correlation between components is found for H + and SO 42- , mutually between Na + Cl -, Mg 2+ and Ca 2+ and between NH 4+ and NO 3-. Absence of correlation between Ca 2+ and SO 42- suggests that SO 42- is not soil derived. The samples are generally slightly acidic which, stochiometrically, can be explained as an imbalance between acidifying components in modest to low concentration and neutralizing components in somewhat lower concentration. The concentrations are lower than those previously reported from stations in eastern and southern Asia, except for some very remote locations.

Granat, L.; Suksomsankh, K.; Simachaya, S.; Tabucanon, M.; Rodhe, H.

189

The Effect of Chemical Functionalization on Mechanical Properties of Nanotube/Polymer Composites  

NASA Technical Reports Server (NTRS)

The effects of the chemical functionalization of a carbon nanotube embedded in a nanotube/polyethylene composite on the bulk elastic properties are presented. Constitutive equations are established for both functionalized and non-functionalized nanotube composites systems by using an equivalent-continuum modeling technique. The elastic properties of both composites systems are predicted for various nanotube lengths, volume fractions, and orientations. The results indicate that for the specific composite material considered in this study, most of the elastic stiffness constants of the functionalized composite are either less than or equal to those of the non-functionalized composite.

Odegard, G. M.; Frankland, S. J. V.; Gates, T. S.

2003-01-01

190

Chemical composition distribution analysis of photoresist copolymers and influence on ArF lithographic performance  

NASA Astrophysics Data System (ADS)

For getting information about the distribution of chemical composition, several model polymers were prepared under different polymerization conditions and were measured by critical adsorption point-liquid chromatography (CAP-LC). In the copolymer system of 8- and 9- (4-oxatricyclo[5.2.1.02,6]decane-3-one) acrylate (OTDA) and 2-ethyl-2-adamantyl methacrylate (EAdMA), the peak shapes of the CAP-LC chromatogram varied according to the polymerization condition although they indicated same molecular weight and averaged chemical composition. The difference of the CAP-LC elution curves was related to the chemical composition distribution of copolymers for CAP-LC measurement combined with proton nuclear magnetic resonance (1H-NMR). The terpolymers consisted of ?-hydroxy-?-butyrolactone methacrylate (GBLMA), 2-methyl-2-adamantyl methacrylate (MAdMA) and 1-hydroxy-3-adamantyl methacrylate (HAdMA) were prepared under various polymerization conditions. In the terpolymer system that had same molecular weight and average chemical composition, the solubility parameter (?) and the dissolution rate were measured. The ? value and the dissolution rate curve were different among these terpolymers. It was suggested that the ? value and the chemical composition distribution of these terpolymers have a significant influence on the lithographic performance.

Momose, Hikaru; Yasuda, Atsushi; Ueda, Akifumi; Iseki, Takayuki; Ute, Koichi; Nishimura, Takashi; Nakagawa, Ryo; Kitayama, Tatsuki

2007-03-01

191

Photochemical evolution of submicron aerosol chemical composition in the Tokyo megacity region in summer  

Microsoft Academic Search

We investigate the chemical transformation of submicron aerosol in the Tokyo megacity region in summer. An Aerodyne quadrupole aerosol mass spectrometer (AMS) was deployed both at an urban site in Tokyo (35°39?N, 139°40?E) and a suburban site (downwind site) in Saitama (36°05?N, 139°33?E) in the summer of 2004. The temporal evolution of size-resolved chemical compositions of submicron (PM1) aerosols during

T. Miyakawa; N. Takegawa; Y. Kondo

2008-01-01

192

Chemical composition of smoke produced by high-frequency electrosurgery in a closed gaseous environment  

Microsoft Academic Search

Background: High-frequency (HF) electrocoagulation and cutting procedures produce smoke by high-temperature pyrolysis of tissues. As\\u000a distinct from the experience of conventional surgery, electrosurgical smoke is produced in a closed gaseous environment during\\u000a laparoscopic operations. As a result, toxic chemicals may be absorbed into the circulation. The effects of this absorption\\u000a are not known. Furthermore, the chemical composition of electrosurgical smoke

C. Hensman; D. Baty; R. G. Willis; A. Cuschieri

1998-01-01

193

Chemical agents and chemical terrorism.  

PubMed

Chemical terrorism is a new threat to the security of mankind, which scale essentially exceeds the impact of use of the most modem firearms. At present time all over the world threats from different radical elements to use radioactive materials, potent poisonous substances and pathogenic microorganisms for terrorist purposes became more frequent. High-toxic chemical substances can fall in terrorist hands through wide range of sources. Potentially misused types of chemical compounds are discussed in this article. PMID:15141987

Patocka, J; Fusek, J

2004-03-01

194

Chemical preconcentrator  

DOEpatents

A chemical preconcentrator is disclosed with applications to chemical sensing and analysis. The preconcentrator can be formed by depositing a resistive heating element (e.g. platinum) over a membrane (e.g. silicon nitride) suspended above a substrate. A coating of a sorptive material (e.g. a microporous hydrophobic sol-gel coating or a polymer coating) is formed on the suspended membrane proximate to the heating element to selective sorb one or more chemical species of interest over a time period, thereby concentrating the chemical species in the sorptive material. Upon heating the sorptive material with the resistive heating element, the sorbed chemical species are released for detection and analysis in a relatively high concentration and over a relatively short time period. The sorptive material can be made to selectively sorb particular chemical species of interest while not substantially sorbing other chemical species not of interest. The present invention has applications for use in forming high-sensitivity, rapid-response miniaturized chemical analysis systems (e.g. a "chem lab on a chip").

Manginell, Ronald P. (Albuquerque, NM); Frye-Mason, Gregory C. (Cedar Crest, NM)

2001-01-01

195

Chemical Name  

Cancer.gov

Attachment III Chemical Quick Reference Chart for Minors Chemical Name Select Carcinogen Reproductive Toxin LD50 < 50 mg/kg (oral rat) LD50 < 200 mg/kg for 24 hours or less (dermal rabbit) LC50 < 200 ppm or 2 mg/L for one hour (inhalation rat)

196

Chemical composition of rainwater at EMEP station in Ankara, Turkey  

NASA Astrophysics Data System (ADS)

The chemical characteristics of rainfall and its seasonal variation at the EMEP (The Cooperative Programme for Monitoring and Evaluation of the Long-Range Transmission of Air Pollutants in Europe) station located in Cubuk, Ankara were studied for the period between September 1994 and December 1996. The station is located in a rural area about 50 km north of Ankara and is considered as a background station for air pollution. The rainwater samples collected were analyzed for pH, major ions concentrations and conductivity. Seasonal variations for some major ions are pronounced. Generally, maximum concentrations appeared in winter or autumn, and minimum concentrations in spring or summer seasons. The average pH of rainwater samples is around 6.3 due to neutralization. Only about 4% of the rain samples had a pH below 5.0 and about 15% of the total rainwater samples had a pH below 5.6. This reflects strong inputs of alkaline species to rainwater samples in this location. The average pH of the samples higher than 5.6 observed in rural area of Ankara is due to a high loading of calcium ions in the form of CaCO 3 because of the alkaline nature of the soil. There is a strong relationship between pHs and other ions in summer. However, in winter, a weak relationship is found between SO 42-, NO 3-, Na + and Mg 2+. On the other hand, relationships between the conductivity and SO 42- concentration are stronger in summer than in winter. The low concentrations of H + found in rainwater samples from Cubuk suggests that an important portion of H 2SO 4 and HNO 3 have been neutralized by alkaline particles in the atmosphere. Weak correlations are found between the hydrogen ions and SO 42- or NO 3- ions for all seasons because of neutralization of these ions with alkaline particles. The dust-rich local and surrounding limestone environment might have caused the high concentration of Ca 2+ in Cubuk area. The relatively high concentration of NH 4+ observed at Cubuk is suspected to be due to surrounding agricultural activity. This agricultural activity has been found to be effective not only in spring, but also in autumn and winter to cause neutralization of the rainwater.

Topçu, Sema; Incecik, Selahattin; Atimtay, Aysel T.

197

Isolation, purification and chemical composition of maize root cap slime  

Microsoft Academic Search

Summary The total root exudate isolated axenically from roots is shown to constitute an extremely heterogenous population of particulate and soluble material. Differences in protein and total sugars contents, and neutral sugar composition throughout stages of total root exudate purification are reported. The importance of controlled collection and purification conditions to ensure valid analysis and composition of purified maize root

Annie Chaboud

1983-01-01

198

Silicon carbide whisker reinforced silicon carbide composites by chemical vapor infiltration  

Microsoft Academic Search

Silicon carbide (SiC) whisker reinforced SiC ceramic matrix composites were prepared by chemical vapor infiltration. Microstructure and mechanical properties of the composites were investigated. The fracture toughness of the composites was improved to 5.65–7.21MPam1\\/2, and its flexural strength value was between 196MPa and 305MPa, depending on the relative density. The pullout of rough whisker, crack deflection and whisker bridging are

Yunfeng Hua; Litong Zhang; Laifei Cheng; Jing Wang

2006-01-01

199

X-ray Tomographic Study of Chemical Vapor Infiltration Processing of Ceramic Composites  

Microsoft Academic Search

The fabrication of improved ceramic-matrix composites will require a better understanding of processing variables and how they control the development of the composite microstructure. Noninvasive, high-resolution methods of x-ray tomography have been used to measure the growth of silicon carbide in a woven Nicalon-fiber composite during chemical vapor infiltration. The high spatial resolution allows one to measure the densification within

J. H. Kinney; T. M. Breunig; T. L. Starr; D. Haupt; M. C. Nichols; S. R. Stock; M. D. Butts; R. A. Saroyan

1993-01-01

200

High toughness, 3D textile, SiC\\/SiC composites by chemical vapor infiltration  

Microsoft Academic Search

Three dimensional, textile, Hi-Nicalon, silicon carbide fiber-reinforced, silicon carbide composites with high toughness and reliability were fabricated by chemical vapor infiltration. The mechanical properties of the composite materials were investigated under bending, shear, and impact loading. The density of the composites was 2.5 g cm?3 after the three dimensional silicon carbide perform has been infiltrated for 30 h. The values

Yongdong Xu; Laifei Cheng; Litong Zhang; Hongfeng Yin; Xiaowei Yin

2001-01-01

201

Histopathology of Human Coronary Atherosclerosis by Quantifying Its Chemical Composition With Raman Spectroscopy  

Microsoft Academic Search

Background—Lesion composition, rather than size or volume, determines whether an atherosclerotic plaque will progress, regress, or rupture, but current techniques cannot provide precise quantitative information about lesion composition. We have developed a technique to assess the pathological state of human coronary artery samples by quantifying their chemical composition with near-infrared Raman spectroscopy. Methods and Results—Coronary artery samples (n5165) obtained from

Tjeerd J. Romer; James F. Brennan III; Maryann Fitzmaurice; Michael L. Feldstein; Geurt Deinum; Jonathan L. Myles; John R. Kramer; Robert S. Lees; Michael S. Feld

202

Chemical vapor infiltration.  

National Technical Information Service (NTIS)

Continuous filament ceramic composites are enabling new, high temperature structural applications. Chemical vapor infiltration methods for producing these composites are being studied, with the complexity of filament weaves and deposition chemistry merged...

T. M. Besmann D. P. Stinton R. A. Lowden

1992-01-01

203

Direct measurement of chemical composition of SOx in impact vapor using a laser gun  

NASA Astrophysics Data System (ADS)

The final chemical composition of vapor clouds created by the impacts higher than 10 km/s is important to investigate the evolution of the planetary surface environment and life. However, no previous experimental study has observed directly it because of experimental difficulties. In this study, we conducted hypervelocity impact experiments using a laser gun and measured the chemical compositions of the impact-generated sulfuric oxides directly. The result clearly shows that the sulfur oxides released by hypervelocity impacts are dominated by SO3, not SO2.

Ohno, Sohsuke; Kadono, T.; Kurosawa, Kosuke; Hamura, Taiga; Sakaiya, Tatsuhiro; Sugita, S.; Shigemori, K.; Hironaka, Yoichiro; Sano, T.; Watari, Takeshi; Otani, K.; Matsui, T.

2012-03-01

204

Model nebulae and determination of the chemical composition of the Magellanic Clouds.  

PubMed

An analysis of previously presented photoelectric spectrophotometry of HII regions (emission-line diffuse nebulae) in the two Magellanic Clouds is carried out with the aid of theoretical nebular models, which are used primarily as interpolation devices. Some advantages and limitations of such theoretical models are discussed. A comparison of the finally obtained chemical compositions with those found by other observers shows generally a good agreement, suggesting that it is possible to obtain reliable chemical compositions from low excitation gaseous nebulae in our own galaxy as well as in distant stellar systems. PMID:16592633

Aller, L H; Keyes, C D; Czyzak, S J

1979-04-01

205

Simultaneous chemical vapor deposition of SiC-dispersed phase composites  

SciTech Connect

Ceramic composites are being developed because they can have high strength and toughness yet retain the normal ceramic attributes of refractoriness and high resistance to abrasion and corrosion. In the present research, toughened ceramic composites were produced by the simultaneous chemical vapor deposition of an SiC matrix and a dispersed phase of TiSi/sub 2/. The morphology of the dispersed phase was found to control the mechanical properties of the composite. Deposition of coatings in a fluidized bed produced a finer and more uniformly dispersed second phase. The conditions within the fluidized bed such as temperature, gas composition, and hydrogen flow also affected the morphology of the TiSi/sub 2/ phase. The fracture toughness values for these composite coatings approached 5.5 MPa..sqrt..m at 25/sup 0/C, which is significantly higher than the toughness value for chemically vapor deposited SiC.

Stinton, D.P.; Lackey, W.J.

1985-01-01

206

Seasonal changes in the chemical and lipid composition of fillets of the Southwest Atlantic hake ( Merluccius hubbsi)  

Microsoft Academic Search

The pH, chemical and lipid composition of fillets of the Southwest Atlantic hake (Merluccius hubbsi) was studied over the course of a year. Mean values for the chemical composition were (wet basis): total non-volatile nitrogen, 2.87%; water, 79.5%; lipids, 1.5%; ash, 1.20%. Water and lipid content were linearly related (P < 0.05). Seasonal changes in the chemical composition were related

Eduardo Méndez; Ruth M. González

1997-01-01

207

The Composition of 433 Eros: A Mineralogical-Chemical Synthesis  

NASA Technical Reports Server (NTRS)

We report on an effort with the Near-Infrared Spectrometer/Multi-Spectral Imager (NIS/MSI) and X-ray/Gamma-ray Spectrometer (XGRS) teams to synthesize our data sets to constrain the relationship between Eros and meteorites; the mineralogy, abundances and compositions of Eros; and the processes that formed Eros. Additional information is contained in the original extended abstract.

McCoy, T. J.; Gaffey, M.; Bell, J. F., III; Boynton, W. V.; Burbine, T. H.; Chapman, C. R.; Cheng, A.; Clark, P. E.; Evans, L. G.; Gorenstein, P.

2001-01-01

208

Chemical composition of cell walls as a taxonomical marker  

Microsoft Academic Search

Matrix sugar composition ofChlorella is species-specifically different. The rigid wall consists of either glucosamine or glucose and mannose. Ruthenium red stainability\\u000a and anisotropy of cell wall are either plus or minus species-specifically. The cell wall is specifically degraded by the lytic\\u000a enzyme of the cell itself.

Hiroshi Takeda

1993-01-01

209

Chemical composition of the lunar surface in mare tranquillitatis.  

PubMed

More precise and comprehensive analytical results have been derived for lunar material at the Surveyor V landing site from alpha-scattering data. The composition is, in general, basaltic; the low sodium and high titanium contents, however, are distinctly different from the abundances in meteorites or common terrestrial rocks. PMID:17814825

Turkevich, A L; Franzgrote, E J; Patterson, J H

1969-07-18

210

MINEQL-EIR. Chemical Equilibrium Composition of Aqueous Systems  

SciTech Connect

MINEQL is a subroutine package to calculate equilibrium composition of an aqueous system, accounting for mass transfer. MINEQL-EIR contains an additional base on enthalpy and heat capacity data and has the option to do calculations at temperatures different from 25 degrees C.

Westall, J.C.; Zachary, J.L.; Morel, F.M.M [Massachusetts Institute of Technology, Cambridge (United States); Schweingruber, M. [Eidgenoessisches Institut for Reaktorforschung, Wuerenlingen (Switzerland)

1986-11-21

211

Genetic alteration of soybean oil composition by a chemical mutagen  

Microsoft Academic Search

Soybean (Glycine max [L.] Merr. cv. Century) seeds were treated with ethylmethanesulfonate (EMS) and the M2 progeny were evaluated for fatty acid composition of the oil. Treatment with EMS significantly increased the variability\\u000a in content of each of the fatty acids in comparison with those of the Century control. There was a strong inverse relationship\\u000a between oleic and linoleic acids

J. R. Wilcox; J. F. Cavins; N. C. Nielsen

1984-01-01

212

Chemical composition of uropygial gland secretions of owls  

Microsoft Academic Search

The compositions of the uropygial gland secretions of the long-eared owl, eagle owl, and barn owl have been deter- mined. The waxes of the first two owls, which are closely relat- ed, are composed of 2-alkyl-substituted fatty acids and n- or mo- nomethyl-branched alcohols with even-numbered branching po- sitions. In addition, some dimethyl-substituted alkanols were ob- served. In contrast to

Jurgen Jacob; Jens Poltz

213

Chemical Peeling  

MedlinePLUS

... to Ask Before a Cosmetic Procedure Chemical Peeling (AAD pamphlet) The Lunchtime Peel: What It Can Do ... et al , editors. Fitzpatrick’s Dermatology in General Medicine . 7 th edition. United States of America, McGraw Hill ...

214

Unnecessary Chemicals  

ERIC Educational Resources Information Center

Discusses the health hazards resulting from chemical additions of many common products such as cough syrups, food dyes, and cosmetics. Steps being taken to protect consumers from these health hazards are included. (MDR)

Johnson, Anita

1978-01-01

215

Chemical Peels  

MedlinePLUS

... a brow lift, eye lift or soft-tissue filler injection. Mild scarring and certain types of acne also can be treated with chemical peels. In addition, pigmentation of the skin in the form of sun spots, age spots, ...

216

Chemical Exposure  

MedlinePLUS Videos and Cool Tools

... 2014 Related MedlinePlus Pages Environmental Health Hormones Transcript Phthalates are a group of chemicals used to make ... the ban has helped lower exposure to some phthalates, while opening the door to others. Researchers looked ...

217

Comparative investigation of the surface properties of commercial titanium dental implants. Part I: chemical composition.  

PubMed

The surfaces of five commercially available titanium implants (Brånemark Nobel Biocare, 3i ICE, 3i OSSEOTITE, ITI-TPS, and ITI-SLA) were compared by scanning electron microscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy. All five implant types were screw-shaped and fabricated from commercially pure (cp) titanium, but their surface properties differed both as regards surface morphology and surface chemical composition. The macro- and microstructure of the implant surfaces were investigated by scanning electron microscopy. The surfaces chemical composition was determined using the surface-sensitive analytical techniques of X-ray photoelectron spectroscopy and time-of-flight secondary ion spectrometry. Surface topographies were found to reflect the type of mechanical/chemical fabrication procedures applied by the manufacturers. The titanium oxide (passive) layer thickness was similar (5-6 nm) and typical for oxide films grown at or near room temperature. A variety of elements and chemical compounds not related to the metal composition were found on some implant types. They ranged from inorganic material such as sodium chloride to specific organic compounds believed to be due to contamination during fabrication or storage. The experimental findings are believed to make a contribution to a better understanding of the interplay between industrial fabrication procedure and physico-chemical implant surface properties. PMID:15348583

Massaro, C; Rotolo, P; De Riccardis, F; Milella, E; Napoli, A; Wieland, M; Textor, M; Spencer, N D; Brunette, D M

2002-06-01

218

[Submerged cultivation and chemical composition of Hericium erinaceus mycelium].  

PubMed

Submerged cultivation of Hericium erinaceus in various media was studied. The yield of the biomass was shown to depend mainly on the carbon source, whereas the content of water soluble polysaccharides depended mainly on the nitrogen source. The optimal medium composition provided the biomass yield of 21-23 g/l in 7 days. The biomass was characterized by the content of total protein, lipids and carbohydrates. In addition, the amino acid composition of the biomass was determined and shown to meet all the requirements of FAO/WHO concerning the amounts of essential amino acids (with exception of tryptophane). Oleinic and linoleic acids were identified as the main components of the fatty acids. Two water soluble polysaccharide fractions differing in solubility in aqueous ethanol were isolated and shown to contain rhamnose, fucose, xylose, glucose and galactose in different proportions. Vitamins B1, B2, B6, PP and E, ergosterol and coenzyme Q were also detected in the biomass of H. erinaceus. PMID:23350189

Avtonomova, A V; Bakanov, A V; Shuktueva, M I; Vinokurov, V A; Popova, O V; Usov, A I; Krasnopol'skaia, L M

2012-01-01

219

Chemical composition of Eastern Black Sea aerosol--preliminary results.  

PubMed

Trace element composition of atmospheric particles collected at a high altitude site on the Eastern Black Sea coast of Turkey was investigated to understand atmospheric transport of pollutants to this semi-closed basin. Aerosol samples were collected at a timber-storage area, which is operated by the General Directorate of Forestry. The site is situated at a rural area and is approximately 50 km to the Black Sea coast and 200 km to the Georgia border of Turkey. Coarse (PM2.5-10) and fine (PM2.5) aerosol samples were collected between 2011 and 2013 using a "stacked filter unit". Collected samples were shipped to the Middle East Technical University in Ankara, where Na, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Ba, Pb were measured by Energy dispersive x-ray fluorescence technique (EDXRF). Comparison of measured concentrations of elements with corresponding data generated at other parts of Turkey demonstrated that concentrations of pollution derived elements are higher at Eastern Black Sea than their corresponding concentrations measured at other parts of Turkey, which is attributed to frequent transport of pollutants from north wind sector. Positive matric factorization revealed four factors including three anthropogenic and a crustal factor. Southeastern parts of Turkey, Georgia and Black Sea coast of Ukraine were identified as source regions affecting composition of particles at our site, using trajectory statistics, namely "potential source contribution function" (PSCF). PMID:24373640

Balc?lar, Ilker; Zarars?z, Abdullah; Kalayc?, Yakup; Do?an, Güray; Tuncel, Gürdal

2014-08-01

220

AN ESTIMATE OF THE CHEMICAL COMPOSITION OF TITAN's LAKES  

SciTech Connect

Hundreds of radar-dark patches interpreted as lakes have been discovered in the north and south polar regions of Titan. We have estimated the composition of these lakes by using the direct abundance measurements from the Gas Chromatograph Mass Spectrometer aboard the Huygens probe and recent photochemical models based on the vertical temperature profile derived by the Huygens Atmospheric Structure Instrument. Thermodynamic equilibrium is assumed between the atmosphere and the lakes, which are also considered nonideal solutions. We find that the main constituents of the lakes are ethane (C{sub 2}H{sub 6}) (approx76%-79%), propane (C{sub 3}H{sub 8}) (approx7%-8%), methane (CH{sub 4}) (approx5%-10%), hydrogen cyanide (HCN) (approx2%-3%), butene (C{sub 4}H{sub 8}) (approx1%), butane (C{sub 4}H{sub 10}) (approx1%), and acetylene (C{sub 2}H{sub 2}) (approx1%). The calculated composition of lakes is then substantially different from what has been expected from models elaborated prior to the exploration of Titan by the Cassini-Huygens spacecraft.

Cordier, Daniel [Ecole Nationale Superieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du General Leclerc, CS 50837, 35708 Rennes Cedex 7 (France); Mousis, Olivier; Lunine, Jonathan I.; Lavvas, Panayotis [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ (United States); Vuitton, Veronique, E-mail: daniel.cordier@ensc-rennes.f [Universite Joseph Fourier, Laboratoire de Planetologie de Grenoble, CNRS/INSU (France)

2009-12-20

221

Toxicological characterization of chemicals produced from laser irradiation of graphite composite materials  

SciTech Connect

One of the major potential hazards associated with laser machining of graphite composite materials is the toxic fumes and gases that are generated. When exposed to the intense energy of the laser beam, the organic polymer matrix of the composite material may decompose into various toxic by-products. To advance the understanding of the laser machining process from a health and safety viewpoint, this particular study consisted of the following steps: collect and analyze gaseous by-products generated during laser machining; collect particulates generated during laser machining and chemically extract them to determine the chemical species that may have absorbed or recondensed onto these particles; and review and evaluate the toxicity of the identified chemical species.

Kwan, J.

1990-11-01

222

Chemical Composition and Manufacturing Technology of a Collection of Various Types of Islamic Glazes Excavated from Jordan  

Microsoft Academic Search

A collection of Islamic glazed pottery shards that were excavated from the archaeological site of Dohaleh\\/Northern Jordan were chemically analysed. The glazes belong to three different decorative styles. The chemical analysis of the glazes was carried out using energy dispersive x-ray fluorescence. The chemical analysis results enable the classification of the glazes into the three distinct compositional groups with reference

Ziad Al-Saad

2002-01-01

223

The chemical composition of fogs and clouds in Southern California  

SciTech Connect

The major inorganic species in cloud and fog water samples were NH{sub 4}{sup +}, H{sup +}, NO{sub 3}{sup {minus}}, and SO{sub 4}{sup 2{minus}}. Concentrations in fog water samples were 1 - 10 {times} 10{sup {minus}3} M; pH values ranged from {approx equal} 2 to 6. Nitrate usually exceeded sulfate. Acidity depended on the availability of NH{sub 3} from agricultural operations. Stratus cloudwater had somewhat lower concentrations; pH values were in the range 3-4. The major factors accounting for variation in fog- or cloudwater composition were the preexisting aerosol and gas concentrations and variations in liquid water content. Deposition and entrainment or advection of different air masses were also important during extended cloud or fog episodes. The droplet size dependence of cloudwater composition was investigated on one occasion in an intercepted coastal stratus clouds. Concentrations of S(IV) and CH{sub 2}O in the range 100-1000 {mu}M were observed in fogwater from urban sites in Southern California. Lower concentrations were observed in stratus clouds. The high levels of S(IV) and CH{sub 2}O were attributed to the formation of hydroxymethanesulfonate (HMSA), the S(IV) adduct of CH{sub 2}O. Direct measurements of HMSA in fogwater samples from Bakersfield, CA were made by ion-pairing chromatography. Glyoxal and methyglyoxal were observed at concentrations comparable to CH{sub 2}O in fogwater samples from Riverside, CA and in stratus cloudwater samples from sites along the Santa Barbara Channel.

Munger, J.W.

1989-01-01

224

Nanoscale chemical interaction enhances the physical properties of bioglass composites.  

PubMed

Bioglasses are favorable biomaterials for bone tissue engineering; however, their applications are limited due to their brittleness. In addition, the early failure in the interface is a common problem of composites of bioglass and a polymer with high mechanical strength. This effect is due to the phase separation, nonhomogeneous mixture, nonuniform mechanical strength, and different degradation properties of two compounds. To address these issues, in this study a nanoscale interaction between poly(methyl methacrylate) (PMMA) and bioactive glass was formed via silane coupling agent (3-trimethoxysilyl)propyl methacrylate (MPMA). A monolith was produced at optimum composition from this hybrid by the sol-gel method at 50 °C with a rapid gelation time (<50 min) that possessed superior physicochemical properties compared to pure bioglass and physical mixture. For instance, the Young's modulus of bioglass was decreased 40-fold and the dissolution rate of silica was retarded 1.5-fold by integration of PMMA. Prolonged dissolution of silica fosters bone integration due to the continuous dissolution of bioactive silica. The primary osteoblast cells were well anchored and cell migration was observed on the surface of the hybrid. The in vivo studies in mice demonstrated that the integrity of the hybrids was maintained in subcutaneous implantation. They induced mainly a mononuclear phagocytic tissue reaction with a low level of inflammation, while bioglass provoked a tissue reaction with TRAP-positive multinucleated giant cells. These results demonstrated that the presence of a nanoscale interaction between bioglass and PMMA affects the properties of bioglass and broadens its potential applications for bone replacement. PMID:24001050

Ravarian, Roya; Zhong, Xia; Barbeck, Mike; Ghanaati, Shahram; Kirkpatrick, Charles James; Murphy, Ciara M; Schindeler, Aaron; Chrzanowski, Wojciech; Dehghani, Fariba

2013-10-22

225

Source apportionment of Baltimore aerosol from combined size distribution and chemical composition data  

Microsoft Academic Search

Several multivariate data analysis methods have been applied to a combination of particle size and composition measurements made at the Baltimore Supersite. Partial least squares (PLS) was used to investigate the relationship (linearity) between number concentrations and the measured PM2.5 mass concentrations of chemical species. The data were obtained at the Ponca Street site and consisted of six days’ measurements:

David Ogulei; Philip K. Hopke; Liming Zhou; J. Patrick Pancras; Narayanan Nair; John M. Ondov

2006-01-01

226

Surface morphology studies of laser irradiated and chemically metalized polyamide composites  

Microsoft Academic Search

Most of polymers need surface treatment prior to be electroless metalized. Conventionally, polymer substrates are cleaned with solvents to remove surface contaminants, then chemically etched to obtain a micro-roughened oxidized surface, and finally seeded with a catalyst such as palladium. In this work, the method consisting in compositional and physical modifications of polyamide (PA6) was applied. Granulated PA6 was mechanically

Piotr Rytlewski; Marian ?enkiewicz; Adam Tracz; Krzysztof Moraczewski; Waldemar Mróz

2011-01-01

227

Determination of the chemical composition of human renal stones with MDCT: influence of the surrounding media  

NASA Astrophysics Data System (ADS)

The selection of the optimal treatment method for urinary stones diseases depends on the chemical composition of the stone and its corresponding fragility. MDCT has become the most used modality to determine rapidly and accurately the presence of stones when evaluating urinary lithiasis treatment. That is why several studies have tempted to determine the chemical composition of the stones based on the stone X-ray attenuation in-vitro and invivo. However, in-vitro studies did not reproduce the normal abdominal wall and fat, making uncertain the standardization of the obtained values. The aim of this study is to obtain X-ray attenuation values (in Hounsfield Units) of the six more frequent types of human renal stones (n=217) and to analyze the influence of the surrounding media on these values. The stones were first placed in a jelly, which X-ray attenuation is similar to that of the human kidney (30 HU at 120 kV). They were then stuck on a grid, scanned in a water tank and finally scanned in the air. Significant differences in CT-attenuation values were obtained with the three different surrounding media (jelly, water, air). Furthermore there was an influence of the surrounding media and consequently discrepancies in determination of the chemical composition of the renal stones. Consequently, CT-attenuation values found in in-vitro studies cannot really be considered as a reference for the determination of the chemical composition except if the used phantom is an anthropomorphic one.

Grosjean, Romain; Sauer, Benoît; Guerra, Rui; Kermarrec, Isabelle; Ponvianne, Yannick; Winninger, Daniel; Daudon, Michel; Blum, Alain; Felblinger, Jacques; Hubert, Jacques

2007-03-01

228

Friction performance of C\\/C composites prepared using rapid directional diffused chemical vapor infiltration processes  

Microsoft Academic Search

A technology used to prepare C\\/C composites using a rapid directional diffused (RDD) chemical vapor infiltration process has been investigated. General RDD technologies were explored, and optimal parameters were determined. The friction and wear properties of this material were researched. The results showed that in the RDD process, propylene and nitrogen were rapidly and directionally diffused into the carbon preforms

Ruiying Luo

2002-01-01

229

Densification of unidirectional carbon–carbon composites by isothermal chemical vapor infiltration  

Microsoft Academic Search

The aim of this research was to investigate the densification of cylindrical unidirectional C–C composites by isothermal chemical vapor infiltration. Several different preforms with different fiber volume fractions were prepared, and it was found that the preforms with the lower fiber volume fraction have a more rapid rate of densification and the final density is higher. The problem of infiltrating

He-Jun Li; Xiang-Hui Hou; Yi-Xi Chen

2000-01-01

230

Chemical Composition Profile and Envelope Parameters in the Modern Solar Model  

Microsoft Academic Search

We study the models of the Sun with gravitational settling and thermal diffusion of elements (specifically helium) during the evolution. These processes are rather slow but they lead to remarkable lowering of helium content in the convection zone as well as to skewing chemical composition profile underneath. We focus on the helium abundance (Y) and the specific entropy in the

S. V. Ayukov; V. A. Baturin

1998-01-01

231

Chemical composition measurements of the atmosphere of Jupiter with the Galileo Probe mass spectrometer  

Microsoft Academic Search

The Galileo Probe entered the atmosphere of Jupiter on December 7, 1995. Measurements of the chemical and isotopic composition of the Jovian atmosphere were obtained by the mass spectrometer during the descent over the 0.5 to 21 bar pressure region over a time period of approximately 1 hour. The sampling was either of atmospheric gases directly introduced into the ion

H. B. Niemann; S. K. Atreya; G. R. Carignan; T. M. Donahue; J. A. Haberman; D. N. Harpold; R. E. Hartle; D. M. Hunten; W. T. Kasprzak; P. R. Mahaffy; T. C. Owen; N. W. Spencer

1998-01-01

232

Galileo Probe Mass Spectrometer Measurements of the Chemical Composition of the Atmosphere of Jupiter  

Microsoft Academic Search

The chemical and isotopic composition of the Jovian atmosphere was measured by the Galileo Probe Mass Spectrometer (GPMS). This data was obtained on December 7, 1995 over a time period of approximately 1 hour during the probe descent in the 0.5 to 20 bar pressure region and transmitted to Earth over a period of several weeks. The sampling was either

H. B. Niemann; J. A. Haberman; D. N. Harpold; R. E. Hartle; W. T. Kasprzak; P. R. Mahaffy; S. K. Atreya; G. R. Carignan; T. M. Donahue; D. M. Hunten; T. C. Owen; N. W. Spencer

1996-01-01

233

Chemical composition measurements of the atmosphere of jupiter with the galileo probe mass spectrometer  

Microsoft Academic Search

The Galileo Probe entered the atmosphere of Jupiter on December 7, 1995. Measurements of the chemical and isotopic composition of the Jovian atmosphere were obtained by the mass spectrometer during the descent over the 0.5 to 21 bar pressure region over a time period of approximately 1 hour. The sampling was either of atmospheric gases directly introduced into the ion

H. B. Niemann; S. K. Atreya; G. R. Carignan; T. M. Donahue; J. A. Haberman; D. N. Harpold; R. E. Hartle; D. M. Hunten; W. T. Kasprzak; P. R. Mahaffy; T. C. Owen; N. W. Spencer

1998-01-01

234

Discerning the Chemical Composition and Mutagenic Effects of Soy Biodiesel PM  

EPA Science Inventory

Discerning the Chemical Composition and Mutagenic Effects of Soy Biodiesel PM David G. Nashab, Esra Mutluc, William T. Prestond, Michael D. Haysb, Sarah H. Warrenc, Charly Kingc, William P. Linakb, M. lan Gilmourc, and David M. DeMarinic aOak Ridge Institute for Science and Ed...

235

Phoebe and Titan: Predicted Bulk Chemical Composition for a Capture Origin  

Microsoft Academic Search

The fast approaching arrival of the Cassini-Huygens spacecraft at Saturn has renewed interest in the origin of this planet and its complex system of moons. Here I report a predicted bulk chemical composition for Phoebe and Titan based on the idea that these bodies are captured satellites which originally condensed as planetesimals within the gas ring shed by the proto-Solar

A. J. R. Prentice

2004-01-01

236

Chemical composition of crystals of cadmium selenochromite doped with indium, silver, or gallium  

SciTech Connect

The authors use an atomic absorption spectrophotometer in an acetylene-air flame to analyze the chemical composition of crystals of cadmium selenochromite doped with indium, silver, and gallium. They tabulate the data gathered and in a chart present the change in the concentration of the main components Cd, Cr, and Se in doped CdCr/sub 2/Se/sub 4/ crystals.

Bel'skii, N.K.; Aminov, T.G.; Ochertyanova, L.I.; Shabunina, G.G.

1985-08-01

237

Essential oils of Retama raetam from Libya: chemical composition and antimicrobial activity  

Microsoft Academic Search

Retama raetam (Forssk) Webb & Berthel is well known in the folk medicine of North and East Mediterranean regions for the treatment of microbial infections. The powdered leaves are used to heal circumcision wounds and used as an antiseptic for wounds, skin rash and pruritus. In this study, to validate this antiseptic property, the chemical composition and antimicrobial activity of

Bahlul Zayed Sh Awen; C. Ramachandra Unnithan; Subban Ravi; Adel Kermagy; J. M. Sasikumar; Amal S. Khrbash; Wafa Lutfi Ekreem

2011-01-01

238

Chemical composition and cytotoxic and antimicrobial activity of Calycotome villosa (Poiret) Link leaves  

Microsoft Academic Search

The chemical composition of the essential oil and methanol extract of Calycotome villosa (Poiret) Link leaves collected in Sardinia (Italy) has been studied by analytical and spectroscopic methods. Falcarinol and some alcohols, terpenes, furan derivatives, and paraffins have been isolated from the essential oil. Thirteen alkaloids and falcarinol have been identified in the chloroform fraction of the basic methanol extract.

Giuseppe Loy; Filippo Cottiglia; Donatella Garau; Delia Deidda; Raffaello Pompei; Leonardo Bonsignore

2001-01-01

239

INFLUENCE OF MINERAL FERTILIZATION ON SELECTED PHYSICAL FEATURES AND CHEMICAL COMPOSITION OF ARONIA FRUIT  

Microsoft Academic Search

A b s t r a c t . Aronia melanocarpa (Michx) Elliot, called also black chokeberry, is a species with lower cultivation requirements within the Rosaceae family. The purpose of the study was to assess the influence of foliar fertilization with Mn, 'Alkalin' (N, K and S i) and Mn + 'Alkalin' on physical features and chemical composition of

Katarzyna Skupie?; Ireneusz Ochmian; Józef Grajkowski

240

Nutrient and Chemical Composition of 13 Wild Plant Foods of Niger  

Microsoft Academic Search

Human populations of the western Sahel depend upon a number of wild plant foods to satisfy a substantial part of their nutritional requirements, and this dependency increases during times of drought. However, the database of the nutrient and chemical compositions of these wild plant foods is incomplete and fragmentary. Herein we report the lipid, fatty acid, amino acid, total protein

Julia A. Cook; Dorothy J. VanderJagt; Andrzej Pastuszyn; Garba Mounkaila; Robert S. Glew; Mark Millson; Robert H. Glew

2000-01-01

241

Antibacterial activity of Turkish propolis and its qualitative and quantitative chemical composition  

Microsoft Academic Search

The antibacterial activity of propolis from different regions of Turkey was studied, accompanied by TLC and GC-MS analyses of its chemical composition and spectrophotometric quantification of the most important active principles. All six samples were active against the bacterial test strains used; however, samples 1 (Yozgat), 2 (Izmir) and 3 (Kayseri) were more active than samples 4 (Adana), 5 (Erzurum)

M. Popova; S. Silici; O. Kaftanoglu; V. Bankova

2005-01-01

242

Chemical composition and functional properties of Ulva lactuca seaweed collected in Tunisia  

Microsoft Academic Search

The chemical composition and some functional properties of the dried “Ulva lactuca” algae, collected from the littoral between the Taboulba and Sayada area, were determined. The dried “U. lactuca” algae were investigated for their soluble, insoluble and total dietary fibre content, mineral amount, amino acid and fatty acid profiles, swelling capacity (SWC), water holding capacity (WHC) and oil holding capacity

Hela Yaich; Haikel Garna; Souhail Besbes; Michel Paquot; Christophe Blecker; Hamadi Attia

2011-01-01

243

Chemical composition of crystals of cadmium selenochromite doped with indium, silver, or gallium  

Microsoft Academic Search

The authors use an atomic absorption spectrophotometer in an acetylene-air flame to analyze the chemical composition of crystals of cadmium selenochromite doped with indium, silver, and gallium. They tabulate the data gathered and in a chart present the change in the concentration of the main components Cd, Cr, and Se in doped CdCrâSeâ crystals.

N. K. Belskii; T. G. Aminov; L. I. Ochertyanova; G. G. Shabunina

1985-01-01

244

Fabrication of fiber-reinforced ceramic composites by chemical vapor infiltration  

SciTech Connect

Ceramic fiber-ceramic matrix composites are of interest because of their potentially higher strength and toughness. A vacuum forming technique was used to fabricate low-density structures from SiC fibers. These fibrous structures were then infiltrated by chemical vapor deposition. Matrices of Si/sub 3/N/sub 4/ and SiC have been deposited.

Caputo, A.J.; Lackey, W.J.

1984-10-01

245

The Effect of Chemical Composition on the Rheological Properties of Asphalts.  

National Technical Information Service (NTIS)

Rheological properties and chemical compositions were determined for 9 paving-grade asphalts. Four of the asphalts were obtained from Arkansas paving projects, and 5 were from the AC-10 series supplied by the U. S. Bureau of Public Roads. A sliding plate ...

C. W. Lamb

1967-01-01

246

Influence of Cultivar on Quality Parameters and Chemical Composition of Strawberry Fruits Grown in Brazil  

Microsoft Academic Search

Six strawberry cultivars grown on the same commercial plantation in Brazil were evaluated for their chemical composition and quality attributes at the ripe stage. The profiles of the main soluble sugars, ascorbic acid, and anthocyanins were also obtained during the developmental stages. Results showed significant differences among cultivars in all of the investigated parameters. Cv. Campineiro showed an average value

Beatriz Rosana Cordenunsi; João Roberto Oliveira do Nascimento; MARIA INE Ä S GENOVESE; Franco Maria Lajolo

2002-01-01

247

Influence of heating on antioxidant activity and the chemical composition of some spice essential oils  

Microsoft Academic Search

Oxidation of lipids is one of the basic processes causing rancidity in food products. Since application of natural antioxidants may be one of the technically simplest ways of reducing fat oxidation, we studied the effect of heating on antioxidant effectiveness and the chemical composition of basil, cinnamon, clove, nutmeg, oregano and thyme essential oils. When maintained at room temperature, all

A. Tomaino; F. Cimino; V. Zimbalatti; V. Venuti; V. Sulfaro; A. De Pasquale; A. Saija

2005-01-01

248

Formation of Denmark Strait overflow water and its hydro-chemical composition  

Microsoft Academic Search

The dense overflow across the Denmark Strait is investigated with hydrographic and hydro-chemical data and the water mass composition of the Denmark Strait Overflow Water (DSOW) is determined by multivariate analysis. Hydrographical properties, the transient tracers CFC-11 and CFC-12, oxygen and nutrients are utilized for the water mass definitions. Distribution and characteristics of water masses north of Denmark Strait are

Toste Tanhua; K. Anders Olsson; Emil Jeansson

2005-01-01

249

EVALUATION OF CHEMICAL COMPOSITION OF FRESH AND FROZEN BLUEBERRY FRUIT (Vaccinium corymbosum L.)  

Microsoft Academic Search

Blueberries are tasteful fruits and are widely believed to be the source of health beneficial compounds, especially phenolics. Freezing is one of the methods of prolonging their supply beyond vegetative season. The aim of the study was to estimate fruit chemical composition of four blueberry culti- vars ('Spartan', 'Bluecrop', 'Jersey' and 'Blueray'). Dry weight, total sugar, total acidity, vitamin C

Katarzyna Skupie

250

Chemical modification of poly(p-phenylene) for use in ablative compositions  

NASA Technical Reports Server (NTRS)

Development of ablative materials based on modification of polyphenylene compounds is discussed. Chemical and physical properties are analyzed for application as heat resistant materials. Synthesis of linear polyphenylenes is described. Effects of exposure to oxyacetylene flame and composition of resultant char layer are presented.

Parker, J. A.; Heimbuch, A. H.; Vincent, D. N.; Hammermesh, C. L.

1972-01-01

251

The ideal ceramic-fibre\\/oxide-matrix composite: how to reconcile antagonist physical and chemical requirements?  

Microsoft Academic Search

Starting with a short historical introduction, this paper deals with the search for the best materials to be used in ceramic composites. The reinforcement and oxide matrix must satisfy multiple - and often antagonist - requirements in terms of physical (failure resistance, damage tolerance) and chemical (thermal stability, corrosion resistance) properties. The best compromise is obtained by \\

Philippe Colomban; Gwénael Gouadec

2005-01-01

252

Numerical simulation of the middle atmosphere chemical composition and temperature under changing solar conditions  

NASA Technical Reports Server (NTRS)

There are given results of the numerical experiments on modelling the influence of solar activity on chemical composition and temperature of the middle atmosphere. The consideration is made for peculiarities of solar activity impact under different values of antropogenic pollution of the atmosphere with chlorofluorocarbons and other stuff.

Zadorozhny, A. M.; Dyominov, I. G.; Tuchkov, G. A.

1989-01-01

253

Chemical composition of a purified membrane fraction from Sarcina aurantiaca in relation to growth phase  

Microsoft Academic Search

The effect of the age of a culture of Sarcina aurantiaca on the chemical composition of the total membrane fraction has been investigated. Whereas the protein content is constant and the carbohydrate increases with age, the lipid content decreases which may be a reflection of increased binding of the lipid to protein. The carbohydrates present in the membrane are mannose,

D. Thirkell; Elizabeth M. M. Gray

1974-01-01

254

Variation of chemical composition with age in human femoral head cartilage  

Microsoft Academic Search

The chemical composition of intact femoral head cartilage was investigated with age. Full-depth cartilage showed a decrease in water content and an increase in keratan sulphate and noncollagenous material with age. When analyzed through the depth of the cartilage, keratan sulphate was shown to appear first in the deep zones and later in the surface, while water content was lost

M F Venn

1978-01-01

255

Mumijo Traditional Medicine: Fossil Deposits from Antarctica (Chemical Composition and Beneficial Bioactivity)  

Microsoft Academic Search

Mumijo is a widely used traditional medicine, especially in Russia, Altai Mountains, Mongolia, Iran Kasachstan and in Kirgistan. Mumijo preparations have been successfully used for the prevention and treatment of infectious diseases; they display immune-stimulating and antial- lergic activity as well. In the present study, we investigate the chemical composition and the biomedical potential of a Mumijo(-related) product collected from

Anna Aiello; Ernesto Fattorusso; Marialuisa Menna; Rocco Vitalone; Heinz C. Schroder; Werner E. G. Muller

256

Introducing a traditional dairy product Ke?: Chemical, microbiological, and sensorial properties and fatty acid composition  

Microsoft Academic Search

In this study, it was aimed to determine the chemical, biochemical, microbiological and sensorial characteristics and fatty acid composition of Ke?, traditionally produced in Bolu province in Turkey. The information on production of 'Ke?' was collected from Bolu province in Turkey. Moreover, 20 samples were taken from the local bazaars in different periods in Bolu. These samples were taken to

Hayri Co?kun; T. Ako?lu; M. Fatih; Mustafa Kiralan; Ali Bayrak

2009-01-01

257

Chemical composition of bone tissue in broiler chickens intended for slaughter  

Microsoft Academic Search

Selected parameters characterizing the chemical composition of bones were determined in 60 male and 60 female hybrid Ross 308 chickens aged 40 days at the end of the fattening period. The chickens received a complete feed mixture intended for pre-feeding (starter) in a period from the start of the experi - ment until Day 10, followed by the feed mixture

P. Suchý; E. Straková; I. Herzig; L. Steinhauser; G. Králik; D. Zapletal

258

Chemical-vapor-infiltrated silicon nitride, boron nitride, and silicon carbide matrix composites  

Microsoft Academic Search

This paper reports composites of carbon\\/chemical-vapor-deposited (CVD) SiâNâ, carbon\\/CVD BN, mullite\\/CVD SiC, and SiC yarn\\/CVD SiC prepared to determine if there were inherent toughness in these systems. The matrices were deposited at high enough temperatures to ensure that they were crystalline, which should make them more stable at high temperatures. The fiber-matrix bonding in the C\\/SiâNâ composite appeared to be

R. D. Ventri; Francis S. Galasso

1990-01-01

259

Phase composition and morphology of TaC coating on carbon fibers by chemical vapor infiltration  

Microsoft Academic Search

Chemical vapor infiltration was applied to deposit TaC thin film on carbon fibers using TaCl5–Ar–C3H6–H2 source. The influence of temperature, pressure and addition of H2 on phase composition and morphology of the coating had been studied. The results showed that the composition of the coating changes with temperature. The films are mainly composed of TaC and C when deposited at

Zhao-ke Chen; Xiang Xiong; Bai-yun Huang; Guo-dong Li; Feng Zheng; Peng Xiao; Hong-bo Zhang; Jian Yin

2008-01-01

260

Aligned carbon nanotube-reinforced silicon carbide composites produced by chemical vapor infiltration  

Microsoft Academic Search

A chemical vapor infiltration (CVI) technique was used to overcome most of the challenges involved in fabricating exceptionally-tough CNT\\/SiC composites. Nanotube pullout and sequential breaking and slippage of the walls of the CNTs during failure were consistently observed for all fractured CNT\\/SiC samples. These energy absorbing mechanisms result in the fracture strength of the CNT\\/SiC composites about an order of

Zhanjun Gu; Yingchao Yang; Kaiyuan Li; Xinyong Tao; Gyula Eres; Jane Y. Howe; Litong Zhang; Xiaodong Li; Zhengwei Pan

2011-01-01

261

Screening of chemical composition, antimicrobial and antioxidant activities of Artemisia essential oils  

Microsoft Academic Search

The chemical composition of essential oils isolated from aerial parts of seven wild sages from Western Canada –Artemisia absinthium L., Artemisia biennis Willd., Artemisia cana Pursh, Artemisia dracunculus L., Artemisia frigida Willd., Artemisia longifolia Nutt. and Artemisia ludoviciana Nutt., was investigated by GC–MS. A total of 110 components were identified accounting for 71.0–98.8% of the oil composition. High contents of

Daíse Lopes-Lutz; Daniela S. Alviano; Celuta S. Alviano; Paul P. Kolodziejczyk

2008-01-01

262

Chemical composition and characteristics of skin gelatin from grey triggerfish ( Balistes capriscus)  

Microsoft Academic Search

Gelatin was extracted from the skin of grey triggerfish (Balistes capriscus) by the acid extraction process with a yield of 5.67 g\\/100 g skin sample on the basis of wet weight. The chemical composition and functional properties of gelatin were investigated. The gelatin had high protein (89.94 g\\/100 g) but low fat (0.28 g\\/100 g) contents. Differences in the amino acid composition between grey triggerfish skin

Kemel Jellouli; Rafik Balti; Ali Bougatef; Noomen Hmidet; Ahmed Barkia; Moncef Nasri

2011-01-01

263

Preparation of ceramic fiber-ceramic matrix composites by a faster chemical vapor infiltration process  

SciTech Connect

A new, faster process was developed for the fabrication of ceramic fiber-reinforced, ceramic-matrix composites by chemical vapor infiltration. Process and equipment improvements led to the fabrication of preforms with a higher fiber content, and infiltration improvements led to reduced infiltration run times and increased infiltrated densities. These improvements have produced composites with not only higher flexural strengths but also high strain values. The high strain values have been a goal of this work. 23 refs., 8 figs.

Caputo, A.J.; Lackey, W.J.; Stinton, D.P.

1985-01-01

264

Chemical composition and antioxidant activity of Strobilanthes crispus leaf extract.  

PubMed

This study investigated the components present in and the total antioxidant activity of leaves of Strobilanthes crispus (L.) Bremek or Saricocalyx crispus (L.) Bremek (Acanthacea). Proximate analyses and total antioxidant activity using ferric thiocyanate and thiobarbituric acid methods were employed. Minerals content was determined using the atomic absorption spectrophotometer, whereas the water-soluble vitamins were determined by means of the UV-VIS spectrophotometer (vitamin C) and fluorimeter (vitamins B(1) and B(2)). Catechin, tannin, caffeine, and alkaloid contents were also studied. All data were compared to the previously reported results of Yerbamate, green tea, black tea, and Indian tea. The dried leaves contained a high amount of total ash (21.6%) as a result of a high amount of minerals including potassium (51%), calcium (24%), sodium (13%), iron (1%), and phosphorus (1%). High content of water-soluble vitamins (C, B(1), and B(2)) contributed to the high antioxidant activity of the leaves. The leaves also contained a moderate amount of other proximate composition as well as other compounds such as catechins, alkaloids, caffeine, and tannin, contributing further to the total antioxidant activity. Catechins of Strobilanthes crispus leaves showed highest antioxidant activity when compared to Yerbamate and vitamin E. Consumption of the leafy extract daily (5 g/day) as an herbal tea could contribute to the additional nutrients and antioxidants needed in the body to enhance the defense system, especially toward the incidence of degenerative diseases. PMID:11137889

Ismail; Manickam; Danial; Rahmat; Yahaya

2000-11-01

265

Chemical composition and bioactivity of Pleiogynium timorense (Anacardiaceae).  

PubMed

A liquid chromatography-diode array detection-electrospray ionization mass spectrometric (HPLC-PDA-ESI/MS/MS) method was used for the analysis of the phenolic composition of the ethanolic extract obtained from the leaves of Pleiogynium timorense (DC.) Leenh. Twenty compounds were detected and tentatively characterized. In addition, further phytochemical investigations of the extract resulted in the isolation of twelve major phenolic compounds. Evidence of the structures of these compounds was obtained based on the interpretation of the UV, 1H NMR, 13C NMR and DQF-COSY spectral data. The antioxidant effect of the ethanolic extract was examined in vitro using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and super oxide anion radical scavenging assays. DPPH radical scavenging activity was observed for the extract, with an IC50 of 21.9 microg/mL, while its super oxide anion scavenging activity was less pronounced, with an IC50 of 123.5 microg/mL The ethanolic extract showed significant hypoglycemic, antioxidant and anti-inflammatory properties. This study suggests that the ethanolic extract of Pleiogynium timorense is a potential source of antioxidant compounds, relatively non-toxic, and have possible beneficial health effects. PMID:20433069

Al Sayed, Eman; Martiskainen, Olli; Sinkkonen, Jari; Pihiaja, Kalevi; Ayoub, Nahla; Singab, Abd-El Naser; El-Azizi, Mohamed

2010-04-01

266

Huygens/ACP: An instrument for aerosols chemical composition measurements  

NASA Technical Reports Server (NTRS)

The Aerosol Collector Pyrolyzer (ACP) which will be used aboard the Huygens probe is introduced. The scientific objectives, scientific rationale, and a technical description of the ACP are given. The ACP will sample the aerosols of the Titan's atmosphere in two regions, 160 to 60 and 60 to 25 km, respectively. In the first region, it will collect aerosol particles absorbed by a complex core (organic polymers) coated with absorbed or condensed molecules. The second collect will sample larger aerosols and the N2-CH4 droplets. In each sampling, the particles are collected on a metallic filter through which the atmospheric gas is pumped. The filter is then inserted into an oven connected to the Gas Chromatograph Mass Spectrometer (GCMS) Experiment which analyzes the gases produced during the heating of the samples. For each sample it will be possible to bring information on the nature and abundance of the volatile components contained in the particles and/or the composition of the photochemical core.

Israel, Guy; Chassefiere, E.; Niemann, Hasso B.; Boon, Jaap J.; Mueller, Christian; Raulin, Francois; Cabane, M.; Sable, Claude

1992-01-01

267

Chemical composition of nuts and seeds sold in Korea  

PubMed Central

Eleven types of nuts and seeds were analyzed to determine their energy (326-733 mg), moisture (1.6-18.3 mg), carbohydrate (8.8-70.9 mg), protein (4.9-30.5 mg), lipid (2.5-69.8 mg), and ash (1.2-5.5 mg) contents per 100 g of sample. Energy content was highest in pine nuts (733 mg/100 g), carbohydrate level was highest in dried figs (70.9 mg/100 g) and protein was highest in peanuts (30.5 mg/100 g). The amino acid compositions of nuts and seeds were characterized by the dominance of hydrophobic (range = 1,348.6-10,284.6 mg), hydrophilic (range = 341.1-3,244.3 mg), acidic (range = 956.1-8,426.5 mg), and basic (range = 408.6-4,738.5 mg) amino acids. Monounsaturated fatty acids (MUFA) were highest in macadamia nuts (81.3%), whereas polyunsaturated fatty acids (PUFA) were highest in the walnuts (76.7%). Macadamia nuts did not contain any vitamin E, whereas sunflower seeds contained the highest level (60.3 mg/kg). Iron (Fe) content was highest in pumpkin seeds (95.85 ± 33.01 ppm), zinc (Zn) content was highest in pistachios (67.24 ± 30.25 ppm), copper (Cu) content was greatest in walnuts (25.45 ± 21.51 ppm), and lead (Pb) content was greatest in wheat nuts (25.49 ± 4.64 ppm), significantly (P < 0.05). In conclusion, current commercial nuts and seeds have no safety concerns, although further analysis of Pb contents is necessary to ensure safety.

Shin, Kyung Ok; Hwang, Hyo Jeong; Choi, Kyung-Soon

2013-01-01

268

Chemical Compatibility and Oxidation Resistance of Potential Matrix and Reinforcement Materials in Ceramic Composites for Ultra-High Temperature Applications.  

National Technical Information Service (NTIS)

The mutual chemical composition and compatibilities of some of the potential matrix and reinforcement phases of ceramic composite materials have been investigated in the temperature range 1600-2200 C. The oxidative stabilities of hot pressed, particulate ...

G. M. Mehrotra

1991-01-01

269

Frost flower chemical composition during growth and its implications for aerosol production and bromine activation  

NASA Astrophysics Data System (ADS)

Frost flowers have been proposed to be the major source of sea-salt aerosol to the atmosphere during polar winter and a source of reactive bromine during polar springtime. However little is known about their bulk chemical composition or microstructure, two important factors that may affect their ability to produce aerosols and provide chemically reactive surfaces for exchange with the atmosphere. Therefore, we chemically analyzed 28 samples of frost flowers and parts of frost flowers collected from sea ice off of northern Alaska. Our results support the proposed mechanism for frost flower growth that suggests water vapor deposition forms an ice skeleton that wicks brine present on newly grown sea ice. We measured a high variability in sulfate enrichment factors (with respect to chloride) in frost flowers and seawater from the vicinity of freezing sea ice. The variability in sulfate indicates that mirabilite precipitation (Na2SO4 · 10 H2O) occurs during frost flower growth. Brine wicked up by frost flowers is typically sulfate depleted, in agreement with the theory that frost flowers are related to sulfate-depleted aerosol observed in Antarctica. The bromide enrichment factors we measured in frost flowers are within error of seawater composition, constraining the direct reactive losses of bromide from frost flowers. We combined the chemical composition measurements with temperature observations to create a conceptual model of possible scenarios for frost flower microstructure development.

Alvarez-Aviles, Laura; Simpson, William R.; Douglas, Thomas A.; Sturm, Matthew; Perovich, Donald; Domine, Florent

2008-11-01

270

Signatures of Earth-Like Planets in the Chemical Composition of Solar-Type Stars  

NASA Astrophysics Data System (ADS)

The formation of terrestrial and gas giant planets has likely imprinted signatures on the chemical composition of their parent stars, as shown for example by the higher occurrence of giant planets for higher stellar metallicities. There are two new signatures that have been recently proposed by Meléndez et al. (2009, 2012) and Ramírez et al. (2009, 2010) for the formation of rocky planets, and by Ramírez et al. (2011) for gas giant planets. We review here our on-going work on the planet-star connection using solar twins, for which chemical abundances are being obtained at unprecedented precision (0.01 dex).

Meléndez, Jorge; Ramírez, Iván

2014-04-01

271

Morphology tailoring of nano/micro-structured conductive polymers, composites and their applications in chemical sensors.  

PubMed

Conductive polymer is one of the important multi-functional materials. It has many applications in light-emitting diodes, chemical sensors, biosensors, et al. This paper provides a relatively comprehensive review on the progress of conductive polymer and composite as sensitive film for sensors to chemical vapors including patents, papers and our preliminary research results. Especially, the feature of conjugated polymers, the processing technology, doping characteristics and some factors affecting gas responses are discussed. Otherwise, the developments of nanostructured conductive polymer and organic-inorganic hybrid film sensor with high sensitivity and rapid response to vapors are also described, and some suggestions are proposed. PMID:20615192

Ma, Xingfa; Gao, Mingjun; He, Xiaochun; Li, Guang

2010-11-01

272

Chemical reactions between aluminum and fly ash during synthesis and reheating of Al-fly ash composite  

Microsoft Academic Search

Thermodynamic analysis indicates that there is the possibility of chemical reactions between aluminum melt and cenosphere\\u000a fly ash particles. These particles contain alumina, silica, and iron oxide, which, during solidification processing of aluminum-fly\\u000a ash composites or during holding of such composites at temperatures above the melting temperature of aluminum, are likely\\u000a to undergo chemical reduction. These chemical reactions between the

R. O. Guo; P. K. Rohatgi

1998-01-01

273

Composite prostheses used to repair abdominal wall defects: physical or chemical adhesion barriers?  

PubMed

In a composite prosthesis, the component placed at the peritoneal interface takes the form of a physical or chemical barrier. In this experimental study performed on the white New Zealand rabbit, several composites were examined to establish the effectiveness of these barriers at impeding adhesion formation. The biomaterials tested were two polypropylene prostheses (PP) with the physical barriers of expanded polytetrafluoroethylene or polyurethane (PP + ePTFE and PP + PU) and two prostheses (one polyester and the other PP) with the absorbable chemical barriers of polyethylene glycol/glycerol and hyaluronate, respectively (PO + gl and PP + hy). The composites were used to repair 7 x 5 cm defects created in the abdominal wall of the animals by placing the implant in contact with the visceral peritoneum and the subcutaneous tissue and fixing it to recipient tissue by 4/0 polypropylene running suture. Fourteen days after surgery the animals were sacrificed and specimens were taken for light microscopy and scanning electron microscopy. Adhesions developing at the prosthesis/visceral peritoneal interface were quantified. All the prostheses induced optimal mesothelialization. Composites with physical barriers behaved similarly in terms of provoking adhesions. However, the prostheses with chemical barriers differed in their effectiveness at preventing adhesions. Overall, the best results were obtained with the PP + PU composite. PMID:15977312

Bellón, J M; Serrano, N; Rodríguez, M; García-Honduvilla, N; Pascual, G; Buján, J

2005-08-01

274

Composition and chemical variability of leaf oil of Myrtus communis from north-eastern Algeria.  

PubMed

The chemical composition of 27 oil samples of Myrtus communis isolated from leaves collected in three locations in north-eastern Algeria was investigated by GC(RI) and 13C NMR spectroscopy. Yields ranged between 0.2-1.2% (w/w). The chemical composition of the oils was largely dominated by monoterpene hydrocarbons, with alpha-pinene (40.5-64.0%), 1,8-cineole (10.9-29.1%) and limonene (6.7-8.2%) being the major compounds. In all the samples, 3,3,5,5,8,8-hexamethyl-7-oxabicyclo[4.3.0]non-1(6)-ene-2,4-dione was identified (0.8-1.5%). The composition is similar to that reported for myrtle oils from Corsica, Sardinia and Tunisia, but differed from that of Moroccan and Spanish myrtle oils. PMID:21121268

Bouzabata, Amel; Boussaha, Faffani; Casanova, Joseph; Tomi, Félix

2010-10-01

275

[Study on the chemical compositions of VOCs emitted by cooking oils based on GC-MS].  

PubMed

Volatile organic compounds (VOCs) are key precursors of ozone and secondary organic aerosols in air, and the differences in the compositions of VOCs lead to their different contribution to atmospheric reaction. Cooking oil fume is one of the important sources of atmospheric VOCs, and its chemical compositions are distinct under different conditions of oil types, food types, cooking methods and heating temperatures etc. In this study, the production of cooking oil fume was simulated by heating typical pure vegetable oils (peanut oil, sunflower oil, soybean oil, olive oil and blend oil) at different temperatures in beakers to investigate the chemical compositions of VOCs. The emitted VOCs were sampled with a Tenax adsorption tube and analyzed using GC-MS after thermal desorption. According to spectral library search and map analysis, using area normalized semi-quantitative method, preliminary qualitative and quantitative tests were conducted for the specific components of VOCs under different conditions. PMID:24640897

He, Wan-Qing; Nie, Lei; Tian, Gang; Li, Jing; Shao, Xia; Wang, Min-Yan

2013-12-01

276

Chemical composition of seeds and oil of Xylopia aethiopica grown in Nigeria.  

PubMed

The chemical composition and mineral constituents of Xylopia aethiopica, which is valued as a spice in Nigeria, were determined along with the physicochemical characteristics of the seed oil. The seeds had the following chemical compositions moisture (8.43 g/100 g), ash (5.89 g/100 g), crude lipid (9.58 g/100 g), crude protein (12.45 g/100 g) crude fiber (8.66 g/100 g) and carbohydrate (63.65 g/100 g). Calcium and potassium were the major minerals in the seed. The extracted lipid was examined for fatty acid composition. Linoleic (45.1 g/100 g) and oleic (26.5 g/100 g) acids were the predominant unsaturated fatty acids, while palmitic acid (18.0 g/100 g) was the major saturated acid. The iodine value of 97 g/100 g indicates that the seed oil is a non-drying type. PMID:10517278

Barminas, J T; James, M K; Abubakar, U M

1999-01-01

277

Ultrafine microstructure composites prepared by chemical vapor deposition. Annual report, January-December 1988  

SciTech Connect

The authors succeeded in preparing dispersed-phase composite coatings which consist of a boron nitride matrix containing aluminum nitride. Chemical vapor deposition (CVD) offers an alternate avenue of preparing ceramic composites by simultaneous deposition of multiple phases (i.e., codeposition). The major advantage of preparing dispersed-phase ceramic composites by CVD is that mechanical as well as chemical, electrical, optical, and thermal properties of the composites can be favorably tailored by controlling the composite composition and microstructure. Dispersed phase composites containing BN+ALN were deposited by CVD. The phases were either amorphous or crystalline depending on the deposition temperature and reagent concentration. One type of deposit which consisted of a turbostratic BN matrix containing oriented single crystal whiskers of ALN was very hard. A qualitative model based on statistical-mechanical nucleation theory and a hypothesized competition between growth of BN and ALN phases was successful in describing the relationship between operating conditions and the resulting microstructure of dispersed phase ceramic (BN+ALN) composites prepared by CVD. This study has provided a fundamental basis for developing more quantitative models, which will integrate the underlying principles of thermodynamics, kinetics, transport phenomena, nucleation and crystal growth theory.

Lackey, W.J.; Freeman, G.B.; Hanigofsky, J.A.; Thompson, J.R.; Gerard, G.J.

1988-12-01

278

40 CFR Table Z-1 to Subpart Z of... - Default Chemical Composition of Phosphate Rock by Origin  

Code of Federal Regulations, 2013 CFR

...2013-07-01 false Default Chemical Composition of Phosphate Rock by Origin Z Table Z-1 to Subpart Z of Part 98 Protection...Subpart Z of Part 98âDefault Chemical Composition of Phosphate Rock by Origin Origin Total carbon(percent by weight)...

2013-07-01

279

Mantle Metasomatism in Mars: Evidence from Bulk Chemical Compositions of Martian Basalts  

NASA Technical Reports Server (NTRS)

Bulk compositions of martian meteorite basalts suggest that they formed from a highly depleted mantle that was variably metasomatised and enriched in incompatible elements. These results are consistent with radio-isotope results. Bulk chemical compositions of basaltic rocks retain clues and tracers to their origins and histories. Interpretations of bulk compositions are not so straight-forward as once envisioned, because real-world magmatic processes can be far from theoretical simple models like one-stage partial melting or closed-system fractional crystallization. Yet, bulk chemistry can shed a broad (if dim) light on Martian basalt petrogenesis that complements the sharply focussed illumination of radio-isotope systematics.

Treiman, A. H.

2003-01-01

280

Multivariate Quantitative Chemical Analysis  

NASA Technical Reports Server (NTRS)

Technique of multivariate quantitative chemical analysis devised for use in determining relative proportions of two components mixed and sprayed together onto object to form thermally insulating foam. Potentially adaptable to other materials, especially in process-monitoring applications in which necessary to know and control critical properties of products via quantitative chemical analyses of products. In addition to chemical composition, also used to determine such physical properties as densities and strengths.

Kinchen, David G.; Capezza, Mary

1995-01-01

281

Chemical composition and acute toxicity in the water after in situ burning--a laboratory experiment.  

PubMed

The chemical composition and toxicity of a water soluble fraction (WSF) of oil versus the underlying water after in situ burning (ISB), has been studied in a laboratory experiment. A system for allowing water sampling after ISB was developed. Seawater samples and oil were collected prior to and immediately after ISB, and chemical analysis was conducted. The chemical characterization of the water showed that the disappearance of water soluble oil components during ISB was insignificant. Acute toxicity tests with the marine copepod Calanus finmarchicus and Microtox® bioassay was performed to establish LC(50)/EC(50) values of the water. The results were compared with regular WAF systems with unburned weathered oil, and indicated no increase in toxicity in the underlying water after ISB. PMID:22112284

Faksness, Liv-Guri; Hansen, Bjørn Henrik; Altin, Dag; Brandvik, Per Johan

2012-01-01

282

Chemical Mahjong  

ERIC Educational Resources Information Center

An open-access, Web-based mnemonic game is described whereby introductory chemistry knowledge is tested using mahjong solitaire game play. Several tile sets and board layouts are included that are themed upon different chemical topics. Introductory tile sets can be selected that prompt the player to match element names to symbols and metric…

Cossairt, Travis J.; Grubbs, W. Tandy

2011-01-01

283

Chemical Wonders  

NSDL National Science Digital Library

Students are introduced to chemical engineering and learn about its many different applications. They are provided with a basic introduction to matter and its different properties and states. An associated hands-on activity gives students a chance to test their knowledge of the states of matter and how to make observations using their five senses: touch, smell, sound, sight and taste.

Integrated Teaching And Learning Program

284

Delicious Chemicals.  

ERIC Educational Resources Information Center

This paper presents an approach to chemistry and nutrition that focuses on food items that people consider delicious. Information is organized according to three categories of food chemicals that provide energy to the human body: (1) fats and oils; (2) carbohydrates; and (3) proteins. Minerals, vitamins, and additives are also discussed along with…

Barry, Dana M.

285

Ultrafine-microstructure composites prepared by chemical vapor deposition. Final report, January 1987-December 1989  

SciTech Connect

In recent years material requirements have become more strict and sophisticated for many novel applications such as space vehicles, ultrasonic jets, ceramic heat engines, high performance cutting tools, etc. It is of great interest to prepare advanced ceramics that possess high temperature stability and strength. A major difficulty exists, however, as the traditional brittleness of ceramics often causes catastrophic failures, thus, limiting their wide usage. Dispersed phase ceramic composites appear to be one solution to this problem. The composites usually possess superior mechanical properties (e.g., fracture toughness, strength, resistance to wear and erosion, hardness, etc.) compared to those of single phase ceramics. The performance of dispersed phase ceramic composites is strongly related to their microstructures. Chemical vapor deposition (CVD) offers an alternative avenue of preparing ceramic composite in the form of coatings by either simultaneous deposition of multiple phases (i.e., codeposition) or by alternately depositing several phases. The major advantage of preparing phase ceramic composites by CVD is that mechanical as well as chemical, electrical, optical and thermal properties of the composites can be favorably tailored by controlling their composition and microstructure. The desired microstructure can be achieved by optimization of CVD process variables such as temperature, pressure, reagent concentration, substrate type, reactor geometry, etc. (KT)

Lackey, W.J.; Freeman, G.B.; Hanigofsky, J.A.; Thompson, J.R.; Gerard, G.J.

1989-12-01

286

Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign  

NASA Astrophysics Data System (ADS)

Particle hygroscopic growth at 90% RH (relative humidity), cloud condensation nuclei (CCN) activity, and size-resolved chemical composition were concurrently measured in the Thüringer Wald mid-level mountain range in central Germany in the fall of 2010. The median hygroscopicity parameter values, ?, of 50, 75, 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.14, 0.14, 0.17, 0.21, 0.24, and 0.28 during the sampling period. The closure between HTDMA (Hygroscopicity Tandem Differential Mobility Analyzers)-measured (?HTDMA) and chemical composition-derived (?chem) hygroscopicity parameters was performed based on the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. Using size-averaged chemical composition, the ? values are substantially overpredicted (30 and 40% for 150 and 100 nm particles). Introducing size-resolved chemical composition substantially improved closure. We found that the evaporation of NH4NO3, which may happen in a HTDMA system, could lead to a discrepancy in predicted and measured particle hygroscopic growth. The hygroscopic parameter of the organic fraction, ?org, is positively correlated with the O : C ratio (?org = 0.19 × (O : C) - 0.03). Such correlation is helpful to define the ?org value in the closure study. ? derived from CCN measurement was around 30% (varied with particle diameters) higher than that determined from particle hygroscopic growth measurements (here, hydrophilic mode is considered only). This difference might be explained by the surface tension effects, solution non-ideality, gas-particle partitioning of semivolatile compounds, and the partial solubility of constituents or non-dissolved particle matter. Therefore, extrapolating from HTDMA data to properties at the point of activation should be done with great care. Finally, closure study between CCNc (cloud condensation nucleus counter)-measured (?CCN) and chemical composition (?CCN, chem) was performed using CCNc-derived ? values for individual components. The results show that the ?CCN can be well predicted using particle size-resolved chemical composition and the ZSR mixing rule.

Wu, Z. J.; Poulain, L.; Henning, S.; Dieckmann, K.; Birmili, W.; Merkel, M.; van Pinxteren, D.; Spindler, G.; Müller, K.; Stratmann, F.; Herrmann, H.; Wiedensohler, A.

2013-08-01

287

Relating particle hygroscopicity and CCN activity to chemical composition during the HCCT-2010 field campaign  

NASA Astrophysics Data System (ADS)

Particle hygroscopic growth at RH =90%, cloud condensation nuclei (CCN) activity, and size-resolved chemical composition were concurrently measured in the Thüringer Wald mid-level mountain range in central Germany in fall season of 2010. The median hygroscopicity parameter values, ?, of 50, 75, 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.14, 0.14, 0.17, 0.21, 0.24, and 0.28 during the sampling period. The closure between HTDMA-measured (?HTDMA) and chemical composition-derived (?chem) hygroscopicity parameters was performed based on the Zdanovskii-Stokes-Robinson (ZSR) mixing rule. Using size-averaged chemical composition, the ? values are substantially overpredicted (30% and 40% for 150 and 100 nm particles). Introducing size-resolved chemical composition substantially improved closure, and the differences between ?HTDMA and ?chem are within 10%. We found that the evaporation of NH4NO3, which may happen in H-TDMA system, could lead to a discrepancy in predicted and measured particle hygroscopic growth. The hygroscopic parameter of the organic fraction, ?org is positively correlated with the O : C ratio (?org =0.19 · (O : C)-0.03). Such correlation is helpful to define the ?org value in the closure study. ? derived from CCN measurement was around 30% (varied with particle diameters) higher than that determined from particle hygroscopic growth measurements (here, hydrophilic mode is considered only). This difference might be explained by the surface tension effects, solution non-ideality, and the partial solubility of constituents or non-dissolved particle matter. However, due to these effects being included in HTDMA-derived ? calculations, we could not distinguish the specific roles of these effects in creating this gap. Therefore, extrapolating from HTDMA data to properties at the point of activation should be done with great care. Finally, closure study between CCNc-measured (?CCN) and chemical composition (?CCN,chem) was performed using CCNc-derived ? values for individual components. The results show that the ?CCN can be well predicted using particle size-resolved chemical composition and the ZSR mixing rule.

Wu, Z. J.; Poulain, L.; Henning, S.; Dieckmann, K.; Birmili, W.; Merkel, M.; van Pinxteren, D.; Spindler, G.; Müller, K.; Stratmann, F.; Herrmann, H.; Wiedensohler, A.

2013-03-01

288

Effect of amine activators on the properties of chemical cured dental composites.  

PubMed

The purpose of this study was to evaluate the reactivity and the effect of concentration of three tertiary amines upon the mechanical properties of a chemical curing dental composite. Chemical cured composite pastes were prepared by keeping peroxide concentration constant at 1 wt% (by weight of resin mixture) and by varying the amine/peroxide molar ratio from 0.25 to 1.5. Composite samples were prepared for all three amine pastes aged for 1, 15, 30, 45, and 60 d stored at 8, 22, and 37 degrees C. The loss in activity of the tertiary amine with time was measured. Changes in compressive strength, diametral tensile strength, and microhardness were also measured. A sharp decrease in working and setting times corresponding to increased activity was noticed with an increased amine content. The activity was found to vary in the order N,N-dimethyl p-toluidine (DMPT) > 2-(4-dimethylaminophenyl)ethanol (DMAPEA) > N,Ndiethanol p-toluidine (DEPT). DMPT is found to be more temperature sensitive than DMAPEA and DEPT. However, DEPT is found to provide better storage stability out of all three amines tested. Each amine was found to possess optimum concentrations at which the mechanical properties showed maximum values. DEPT is preferred for long-term storage stability in chemical-cured dental composites where aging tends to reduce the activity of the amine. PMID:9067811

Mathew, L; Joseph, R; Krishnan, V K

1997-01-01

289

Chemical composition of the volatile oil from Zanthoxylum avicennae and antimicrobial activities and cytotoxicity  

PubMed Central

Background: Through literature retrieval, there has been no report on the research of the chemical components in Zanthoxylum avicennae (Lam.) DC. This paper extracted and determined the chemical components of the volatile oil in Z. avicennae, and at the same time, measured and evaluated the bioactivity of the volatile oil in Z. avicennae. Materials and Methods: We extract the volatile oil in Z. avicennae by steam distillation method, determined the chemical composition of the volatile oil by GC-MS coupling technique, and adopt the peak area normalization method to measured the relative percentage of each chemical composition in the volatile oil. Meanwhile, we use the Lethal-to-prawn larva bioactivity experiment to screen the cytotoxicity activities of the volatile oil in Z. avicennae, and using the slanting test-tube experiment to determine and evaluate its antibacterial activities in vitro for the eight kinds of plant pathogenic fungi in the volatile oil of the Z. avicennae. Results: The results show that 68 kinds of compounds are determined from the volatile oil of Z. avicennae. The determined part takes up 97.89% of the total peak area. The main ingredients in the volatile oil of Z. avicennae are sesquiterpenoids and monoterpene. The test results show that the volatile oil in Z. avicennae has strong antibacterial activities and cytotoxicity, with the strongest antibacterial activity against the Rhizoctonia solani AG1-1A. Conclusion: This research results will provide reference data for understanding the chemical composition of the volatile oil in the aromatic plant of Z. avicennae and its bioactivity, and for its further development and application.

Lin, Yin; Han, Wei; Ge, Wei-chen; Yuan, Ke

2014-01-01

290

Effect of chemical degradation followed by toothbrushing on the surface roughness of restorative composites  

PubMed Central

Objectives The aim of the present study was to assess the effect of the exposure to food-simulating liquids prior to brushing simulation on the surface roughness of five composite materials (Quixfil, Filtek Supreme, Esthet-X, Filtek Z250, Tetric Ceram). Material and methods Twenty cylinders (5 mm diameter and 4 mm height) of each composite were randomly allocated to 4 groups (n=5), according to the food-simulating liquid in which they were immersed for 7 days at 37ºC: artificial saliva, heptane, citric acid, and ethanol. After this period, the top surface of composite cylinders was submitted to 7,500 brushing cycles (200 g load). Measurements of the surface roughness (Ra, µm) were carried out before and after the exposure to the chemicals/brushing simulation. Changes on the morphology of composite surfaces were observed through scanning electron microscopy (SEM). Results The statistical analysis (ANOVA with cofactor / Tukey's test, ?=5%) detected a significant interaction between solutions and composite resins. Esthet-X, Filtek Z250 and Tetric Ceram were not affected by the food-simulating liquids/toothbrushing. Citric acid and ethanol increased the surface roughness of Quixfil and Filtek Supreme, respectively. SEM images corroborate the surface roughness findings, demonstrating the negative effect from chemical solutions and mechanical abrasion. Conclusions The surface roughness of composite resin materials are differently affected by the food-simulating solutions, depending on the immersion media.

VOLTARELLI, Fernanda Regina; dos SANTOS-DAROZ, Claudia Batitucci; ALVES, Marcelo Correa; CAVALCANTI, Andrea Nobrega; MARCHI, Giselle Maria

2010-01-01

291

Water-soluble lipoproteins from yolk granules in sea urchin eggs. II. Chemical composition.  

PubMed

The chemical composition of yolk lipoproteins (YLP-1, 2, and 3) was determined. YLP-1, 2, and 3 were quite similar as regards the chemical composition of lipids, proteins, and carbohydrate moieties. Each lipoprotein has an average dry weight composition of lipids (55--72%) and apo-lipoproteins (28--45%) containing protein, hexose, hexosamine, and sialic acid. In each lipoprotein, triacylglycerol is a major lipid component (70--83%), followed by phospholipid (8--16%), cholesterol (free and esterified, 8--10%), and free fatty acid (3--4%). Phosphatidylcholine and phosphatidylserine account for 68--74% and 16--24% of the phospholipids, respectively. The fatty acid compositions of total lipids from each lipoprotein are quite similar, with a high degree of unsaturation (63--65%). The carbohydrate content of apolipoprotiens from each lipoprotein is remarkably high (27--31% of apo-lipoproteins) and their composition is very simple: mannose and glucosamine are major constituents in the polysaccharide moiety of each lipoprotein and sialic acid is all in the N-glycolyl form. The amino acid compositions of apo-lipoproteins are quite similar in YLP-1, 2, and 3, with high contents of aspartic acid, glutamic acid, threonine, serine, and leucine. Furthermore, a small amount of glycolipids is present in the yolk lipoproteins. They were separated into six components on TLC. All of them are resorcinol-positive, indicating the presence of sialoglycolipids. PMID:457646

Deguchi, K; Kawashima, S; Ii, I; Ueta, N

1979-06-01

292

Computational scheme for ab-initio predictions of chemical compositions interfaces realized by deposition growth  

NASA Astrophysics Data System (ADS)

We present a novel computational scheme to predict chemical compositions at interfaces as they emerge in a growth process. The scheme uses the Gibbs free energy of reaction associated with the formation of interfaces with a specific composition as predictor for their prevalence. It explicitly accounts for the growth conditions by rate-equation modeling of the deposition environment. The Bell-Evans-Polanyi principle motivates our emphasis on an effective nonequilibrium thermodynamic description inspired by chemical reaction theory. We illustrate the scheme by characterizing the interface between TiC and alumina. Equilibrium thermodynamics favors a nonbinding interface, being in conflict with the wear-resistant nature of TiC/alumina multilayer coatings. Our novel scheme predicts that deposition of a strongly adhering interface is favored under realistic conditions.

Rohrer, Jochen; Hyldgaard, Per

2011-09-01

293

Chemical composition of endemic Scorzonera sandrasica and studies on the antimicrobial activity against multiresistant bacteria.  

PubMed

The present study describes the antimicrobial activity and chemical composition of Scorzonera sandrasica Hartvig et Strid (Family Asteraceae), endemic to Turkey. The antimicrobial activity of the hexane, chloroform, ethyl acetate, and ethanol extracts of the aerial parts of S. sandrasica was evaluated against microorganisms, including multiresistant bacteria, using a paper disc diffusion method. The chemical composition of the chloroform extract of the plant was determined by gas chromatography and gas chromatography-mass spectrometry. The major compounds of the chloroform extract of the plant were caryophyllene oxide (19.7%), manoyl oxide (16.5%), and manool (11.3%), respectively. The extracts had antibacterial activity; however, no antifungal activity was observed against the two fungi. In particular, the ethanol and chloroform extracts exhibited significant activity against multiresistant strains of Stenotrophomonas maltophilia. PMID:20438328

Ugur, Aysel; Sarac, Nurdan; Ceylan, Ozgur; Duru, M Emin; Beyatli, Yavuz

2010-06-01

294

[Characteristics of chemical composition of glass finds from the Qiemo tomb sites on the Silk Road].  

PubMed

Qiemo was an ancient country on the south branch of the Silk Road. The Zagunluke tomb site is located at the Qiemo County of the Xinjiang Uygur Autonomous Region. Glass beads and only colourless glass cup were excavated from the 3rd cultural layer of the tomb site M133 and M49, dated between the 1st AD-6th AD. LA-ICP-AES was applied to analyse chemical composition of these glass finds with the corning glass as reference. According to the result, characteristics of chemical composition are very similar to typical soda-lime glass, which indicates the glasses were imported productions from the west. These soda-lime glasses were divided into two groups in terms of flux source: natron glass and plant ash glass. This analytical research indicates the history of glass trade and communication between the East and the West on the Silk Road. PMID:23016362

Cheng, Qian; Guo, Jin-Long; Wang, Bo; Cui, Jian-Feng

2012-07-01

295

SiC whisker/Si3N4 composites by a chemical mixing process  

SciTech Connect

A chemical mixing process has been developed for making SiC whisker/Si3N4 composites. The process involves in situ synthesis of SiC whiskers in Si3N4 powder by partial carbothermal reduction of silicon nitride in an argon atmosphere. The effects of reaction conditions and starting raw materials on the formation of SiC whiskers were studied. It has been demonstrated that the morphologies of the in situ synthesized whiskers can be modified by varying carbon-source materials and reaction conditions, and the amount of SiC formed in the product can be adjusted by changing the starting Si3N4-to-C ratio. The chemically mixed composite materials were densified by hot pressing with Y2O3 and Al2O3 as sintering aids. 12 refs.

Wang, Hongyu; Fischman, G.S.

1991-10-01

296

Chemical composition and antimicrobial activity of Satureja hortensis and Trachyspermum copticum essential oil  

PubMed Central

Background and Objectives The aim of this study was to evaluate the chemical composition and antimicrobial activity of Satureja hortensis and Trachyspermum copticum essential oils against different kinds of microorganisms in vitro. Material and Methods The antimicrobial activity was evaluated by micro broth dilution assay and the chemical composition of essential oils was analyzed by GC and GC/MS. Results Thymol, p-cymene, ?-terpinene and carvacrol were the main components of S. hortensis oil while thymol, ?-terpinene, and o-cymene were the major components of T. copticum oil. Two essential oils exhibited strong antimicrobial activity but the antimicrobial activity of T. copticum oil was higher than that of S. hortensis oil. Conclusion Thymol as a main component of oils plays an important role in antimicrobial activity.

Mahboubi, M; Kazempour, N

2011-01-01

297

Chemical composition and antibacterial activity of essential oil and extracts of Citharexylum spinosum flowers from Thailand.  

PubMed

The chemical composition and antibacterial and antioxidant activities of the essential oil and various solvent extracts of Citharexylum spinosum flowers are reported. The chemical compositions were determined by GC-MS with 151 volatile constituents identified. Methyl benzoate, piperitone, maltol, and maple furanone were the major constituents. All extracts were tested for their antibacterial activity against eight microorganisms. The flower oil had the greatest antibacterial activity against all bacterial strains (MIC values of 31.2 microg/mL), while the other solvent extracts had MIC values ranging from 31.2 to 1000 microg/mL. The essential oil had the highest antioxidant activity and total phenol content with IC50 values of 62.7 and 107.3 microg/mL, respectively. PMID:25026728

Mar, Ae; Pripdeevech, Patcharee

2014-05-01

298

Expected gamma-ray emission spectra from the lunar surface as a function of chemical composition  

NASA Technical Reports Server (NTRS)

The gamma rays emitted from the moon or any similar body carry information on the chemical composition of the surface layer. The elements most easily measured are K, U, Th and major elements such as O, Si, Mg, and Fe. The expected fluxes of gamma ray lines were calculated for four lunar compositions and one chondritic chemistry from a consideration of the important emission mechanisms: natural radioactivity, inelastic scatter, neutron capture, and induced radioactivity. The models used for cosmic ray interactions were those of Reedy and Arnold and Lingenfelter. The areal resolution of the experiment was calculated to be around 70 to 140 km under the conditions of the Apollo 15 and 16 experiments. Finally, a method was described for recovering the chemical information from the observed scintillation spectra obtained in these experiments.

Reedy, R. C.; Arnold, J. R.; Trombka, J. I.

1973-01-01

299

Determination of Chemical Compositions on Adult Kidney Stones-A Spectroscopic Study  

NASA Astrophysics Data System (ADS)

The chemical compositions of the kidney stones of both the sexes of patients, aged from 40 to 70, living in and around Chidambaram town are determined by using FT-IR and X-RD technique. The kidney stone samples used in the present study were procured from the Rajah Muthiah Medical College and Hospital, Annamalai University. The FT-IR spectra of different kidney stone samples were recorded in the range of 4000-400 cm-1. By identifying the characteristic frequency, the chemical compositions of the samples are determined. The results analyzed by FTIR technique were confirmed by X-RD method, in which the recorded X-ray diffractogram are compared with JCPDS files using search match method. Further analysis of XRD pattern also reveals the same.

Raju, K.; Rakkappan, C.

2008-11-01

300

Influence of chemical composition of precipitation on migration of radioactive caesium in natural soils.  

PubMed

The aim of the present work was to study the impact of the chemical composition of precipitation on radiocaesium mobility in natural soil. This was done through column studies. Three types of precipitation regimes were studied, representing a natural range found in Norway: Acidic precipitation (southernmost part of the country); precipitation rich in marine cations (highly oceanic coastal areas); and low concentrations of sea salts (slightly continental inland areas). After 50 weeks and a total precipitation supply of ?10 000 L m(-2) per column, results indicate that acidic precipitation increased the mobility of (134)Cs added during the experiment. However, depth distribution of already present Chernobyl fallout (137)Cs was not significantly affected by the chemical composition of precipitation. PMID:24704765

Thørring, H; Skuterud, L; Steinnes, E

2014-08-01

301

Microflora and chemical composition of dental plaque from subjects with hereditary fructose intolerance.  

PubMed Central

We compared the microbiological and chemical composition of dental plaque from subjects with hereditary fructose intolerance who restrict their dietary sugar intake with that of control subjects who do not. The two groups showed no significant differences in chemical composition of plaque: the mean protein, carbohydrate, calcium, magnesium, and phosphate contents were similar. Dental plaque from both groups contained similar numbers of total colony-forming units per microgram of plaque protein, and Streptococcus sanguis, an indigenous nonpathogen, was isolated with equal frequency from plaque samples of both groups. However, potentially odontopathic Streptococcus mutans and Lactobacillus were isolated three to four times more frequently from plaque samples of control subjects than from plaque samples of subjects with hereditary fructose intolerance. Clearly, diet (sucrose in particular) influences the colonization and multiplication of specific cariogenic organisms in dental plaque.

Hoover, C I; Newbrun, E; Mettraux, G; Graf, H

1980-01-01

302

Chemical Composition and Nutritional Value of Unripe Banana Flour ( Musa acuminata , var. Nanicão)  

Microsoft Academic Search

Banana flour obtained from unripe banana (Musa acuminata, var. Nanicão) under specific drying conditions was evaluated regarding its chemical composition and nutritional value. Results\\u000a are expressed in dry weight (dw). The unripe banana flour (UBF) presented a high amount of total dietary fiber (DF) (56.24 g\\/100 g),\\u000a which consisted of resistant starch (RS) (48.99 g\\/100 g), fructans (0.05 g\\/100 g) and DF without RS or fructans

Elizabete Wenzel Menezes; Carmen Cecília Tadini; Tatiana Beatris Tribess; Angela Zuleta; Julieta Binaghi; Nelly Pak; Gloria Vera; Milana Cara Tanasov Dan; Andréa C. Bertolini; Beatriz Rosana Cordenunsi; Franco M. Lajolo

303

Chemical composition of teff (Eragrostis tef) compared with that of wheat, barley and grain sorghum  

Microsoft Academic Search

The chemical composition of teff, analyzed from uncontaminated seeds, revealed the superiority of the species in mineral nutritive\\u000a value. Teff’s exceedingly high iron and calcium content was confirmed. The high iron content of teff reported by the Ethiopia\\u000a Nutrition Survey must have been due to certain inherent factors of the species, not only a result of contamination. The magnitude\\u000a of

Melak H. Mengesha

1966-01-01

304

Effect of Germination on the Chemical Composition and Nutritive Value of Amaranth Grain  

Microsoft Academic Search

Cereal Chem. 67(6):5 19-522 Changes in chemical composition and in nutritive value during germi- in protein, crude fiber, and ash content, whereas lipid and phytic acid nation of amaranth grain were studied. One variety each of Amaranthus content decreased with respect to germination time. Reducing sugars, hypochondriacus, A. cruentus, and A. caudatus was germinated for 0, total sugars, and damaged

A. S. COLMENARES DE RUIZ; R. BRESSANI

305

Effects of space radiation on a chemically modified graphite-epoxy composite material. Interim report  

Microsoft Academic Search

The effects of the space environment on the engineering properties and chemistry of a chemically modified T300\\/934 graphite-epoxy composite system are characterized. The material was subjected to 1.0 x 10 to the 10th power rads of 1.0 MeV electron irradiation under vacuum to simulate 30 years in geosynchronous earth orbit. Monotonic tension tests were performed at room temperature (75 F\\/24

S. M. Reed; C. T. Herakovich; G. F. Sykes

1986-01-01

306

Brazilian Ginseng extraction via LPSE and SFE: Global yields, extraction kinetics, chemical composition and antioxidant activity  

Microsoft Academic Search

Brazilian Ginseng extracts of two species, Pfaffia paniculata and Pfaffia glomerata, were obtained by supercritical fluid extraction (SFE) with CO2 and by low-pressure solvent extraction (LPSE) with methanol, hexane and ethanol. The SFE assays were conducted at pressures of 100, 200 and 300bar, and temperatures of 30 and 50°C. The qualitative chemical compositions of the extracts were determined by thin

Patrícia F. Leal; Marina B. Kfouri; Fábio C. Alexandre; Fábio H. R. Fagundes; Juliana M. Prado; Marcos H. Toyama; M. Angela A. Meireles

2010-01-01

307

Modeling of an improved chemical vapor infiltration process for ceramic composites fabrication  

Microsoft Academic Search

A quasi-steady-state approach is applied to model the pressure-driven, temperature-gradient chemical vapor infiltration (improved CVI process) for ceramic matrix composites fabrication. The deposited matrix in this study is SiC which is converted from the thermal decomposition of methyltrichlorosilane gas under excess hydrogen. A three-dimensional unit cell is adopted to simulate the spatial arrangements of reinforcements in discontinuous fiber mats and

Nyan-Hwa Tai; Tsu-Wei Chou

1990-01-01

308

Chemical vapor infiltration (CVI)—Part I: a new technique to achieve diamond composites  

Microsoft Academic Search

Diamond\\/metal or diamond\\/ceramics penetration structures have a high potential as, e.g. heat sinks in the microelectronic industry and for tribological applications. To learn more about the basic principles in fabricating these new composites, we infiltrated porous structures of silicon carbide with diamond by chemical vapor infiltration (CVI). As a result we get a 3D penetration structures of diamond and substrate.

A. Glaser; S. M. Rosiwal; B. Freels; R. F. Singer

2004-01-01

309

Chemical composition and radioactivity in hokutolite (plumbian barite) collected at Peito hot spring, Taiwan  

Microsoft Academic Search

Chemical composition and radionuclide concentrations were determined for hokutolite, plumbian barite, collected at Peito hot spring, Taiwan. The hokutolite, precipitated on the surface of the base rock, was scraped into 20 layers from the surface. Barium and Pb were determined by inductively coupled plasma-atomic emission spectroscopy, and 228Ra, 226Ra and 210Pb were determined by ?-ray spectrometry. Comparison of the 228Ra226Ra

Noriyuki Momoshima; Junichi Nita; Yonezo Maeda; Sinji Sugihara; Isamu Shinno; Nobuaki Matsuoka; Chin-Wang Huang

1997-01-01

310

Chemical composition and antibacterial activity of Pinus halepensis Miller growing in West Northern of Algeria  

PubMed Central

Objective To find new bioactive natural products, the chemical composition and to sudy the antibacterial activity of essential oil components extracted from the aerial parts of the Algerian aromatic plant Pinus halepensis Miller (P. halepensis) (needles, twigs and buds). Methods The essential oil used in this study was isolated by hydrodistillation using a Clevenger-type apparatus according to the European Pharmacopoeia. The chemical composition was investigated using GC-retention indices (RI) and GC-MS. Results Forty-nine compounds, representing 97.9% of the total collective oil, were identified. Essential oil was dominated by hydrocarbon compounds (80.6%) especially monoterpenes (65.5%). The major compounds from ten oils stations were: myrcene (15.2%-32.0%), ?-pinene (12.2%-24.5%), E-?-caryophyllene (7.0%-17.1%), terpinolene (1.8%-13.3%), 2-phenyl ethyl isovalerate (4.8%-10.9%), terpinene-4-ol (1.0%-8.2 %) and sabinene (1.5%-6.3%). The intra-species variations of the chemical compositions of P. halepensis aerial parts essential oils from ten Algerian sample locations were investigated using statistical analysis. Essential oil samples were clustered in 2 groups by hierarchical cluster analysis, according to their chemical composition. The essential oil revealed an interesting antimicrobial effect against Lysteria monocytogenes, Enterococcus faecalis, Pseudomonas aeruginosa, Acinetobacter baumanii, Citrobacter freundii and Klebsiella pneumoniae. Conclusions These results suggest that the essential oil from P. halepensis may be a new potential source as natural antimicrobial applied in pharmaceutical and food industries.

Fekih, Nadia; Allali, Hocine; Merghache, Salima; Chaib, Faiza; Merghache, Djamila; El Amine, Mohamed; Djabou, Nassim; Muselli, Alain; Tabti, Boufeldja; Costa, Jean

2014-01-01

311

Evolution of pH and chemical composition of pore solution in carbonated concrete  

Microsoft Academic Search

An investigation of carbonation in concrete, the pH and chemical composition change of the pore solution in concrete with different degrees of carbonation, was presented. The concrete samples were manufactured using ordinary portland cement and fly ash with dimension of 100mm diameter by 3mm in height, and six different mix proportions. The concrete samples were exposed to the environment (CO2

Qi Pu; Linhua Jiang; Jinxia Xu; Hongqiang Chu; Yi Xu; Yan Zhang

312

Chemical Compositions of Aerial Part Essential Oils of Lantana camara L. Chemotypes from Madagascar  

Microsoft Academic Search

The chemical composition of 12 essential oil samples of the aerial parts of two flower color types of Lantana camara from Madagascar collected each month of the year, have been characterized by GC and GC\\/MS. The main components changed within the two flower color types. The pink-violet flower type contained mainly davanone (23.5%), ?-caryophyllene (11.7%), sabinene (10.4%), linalool (5.9%) and

Jean-Aimé Randrianalijaona; Panja A. R. Ramanoelina; Jean R. E. Rasoarahona; Emile M. Gaydou

2006-01-01

313

Seasonal and chemotype influences on the chemical composition of Lantana camara L  

Microsoft Academic Search

Yellow-orange and pink-violet colours of flower plants of Lantana camara from Madagascar were studied with a focus on essential oil (EO) in order to characterize chemotype EO variability. The chemical composition of 73 samples of aerial part EO of L. camara collected each month of the year, at various location, have been characterized by gas chromatography-mass spectrometry (GC-MS). Among the

Jean-Aimé Randrianalijaona; Panja A. R. Ramanoelina; Jean R. E. Rasoarahona; Emile M. Gaydou

2005-01-01

314

The essential oil of Senecio graveolens ( Compositae): chemical composition and antimicrobial activity tests  

Microsoft Academic Search

The chemical composition of the essential oil obtained from Senecio graveolens (Compositae) was analyzed by GLC–MS and the components identified were: isovaleraldehyde, ?-pinene, ?-phellandrene, ?-terpinene, p-cymene, sabinene, ?-terpinene, 1-methyl-4-isopropenylbenzene, terpinolene, terpinen-4-ol, piperitenone, ?- and ?-eudesmol. The investigation by the agar-well diffusion method of the antimicrobial activity of the essential oil proved that it has antibacterial effects on Micrococcus luteus ATCC

Cristina Pérez; Alicia Mariel Agnese; José Luis Cabrera

1999-01-01

315

Comparative investigation of the surface properties of commercial titanium dental implants. Part I: chemical composition  

Microsoft Academic Search

The surfaces of five commercially available titanium implants (Brånemark Nobel Biocare, 3i ICE, 3i OSSEOTITE, ITI-TPS, and ITI-SLA) were compared by scanning electron microscopy, X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectroscopy. All five implant types were screw-shaped and fabricated from commercially pure (cp) titanium, but their surface properties differed both as regards surface morphology and surface chemical composition. The

C. Massaro; P. Rotolo; F. De Riccardis; E. Milella; A. Napoli; M. Wieland; M. Textor; N. D. Spencer; D. M. Brunette

2002-01-01

316

Effects of cooking, germination and fermentation on the chemical composition of Nigerian Cowpea ( Vigna unguiculata )  

Microsoft Academic Search

The effects of cooking, germination, and fermentation on the chemical composition of cowpea were studied. There were noticeable trends in the protein, carbohydrate and crude fiber as a result of the different treatments. Both the germinated and fermented samples contained more ether extractable lipids than the raw and cooked samples. Untreated raw cowpea contained 5.9 mg\\/g phytic acid, 1.66 mg\\/g

M. A. Akpapunam; S. C. Achinewhu

1985-01-01

317

Neem cake: chemical composition and larvicidal activity on Asian tiger mosquito.  

PubMed

New pesticides based on natural products are urgently needed, in consideration of their environmental care and lower collateral effects. Neem oil, the main product obtained from Azadiractha indica A. Juss, commonly known as neem tree, is mainly used in medical devices, cosmetics and soaps, as well as important insecticide. Manufacturing of neem oil first includes the collection of the neem seeds as raw material used for the extraction. Neem cake is the waste by-product remaining after extraction processes. The quality of the oil, as that of the cake, strictly depends from the quality of seeds as well as from the type of extraction processes used, which strongly influences the chemical composition of the product. Currently, the different types of commercial neem cake on the market are roughly identified as oiled and deoiled cake, but several other differences can be detected. The differences are relevant and must be determined, to obtain the necessary correlation between chemical constitution and larvicidal activities. Six different batches of neem cake, marketed by several Indian and European companies, were analyzed by HPLC and HPTLC, and their fingerprints compared, obtaining information about the different compositions, focusing in particular on nortriterpenes, considered as the main active components of neem oil. Therefore, the chemical composition of each cake was connected with the biological activitiy, i.e., the effects of the extracts of the six neem cakes were tested on eggs and larvae of Aedes albopictus (Stegomyia albopicta) (Diptera: Culicidae), commonly known as Asian tiger mosquito. The results confirmed the previously reported larvicide effects of neem cake that, however, can now be related to the chemical composition, in particular with nortriterpenes, allowing in that way to discriminate between the quality of the various marketed products, as potential domestic insecticides. PMID:22422292

Nicoletti, Marcello; Mariani, Susanna; Maccioni, Oliviero; Coccioletti, Tiziana; Murugan, Kardaray

2012-07-01

318

Polysulfone-polypyrrole ionic conductive composite membranes synthesized by phase inversion with chemical reaction  

Microsoft Academic Search

New polymeric composite membranes polysulfone-polypyrrole has been prepared by a new technique consisting in phase inversion accompanied by chemical reaction. The membranes were synthesised from polysulfone\\/pyrrole-N, N'-dimethylformamide\\/ methanol system by phase inversion followed by remaining pyrrole in membrane pores polymerization in the presence of iron chloride. The obtained membrane was characterized by Fourrier transformed infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA),

C. Muscalu; R. David; S. A. Garea; A. C. Nechifor; D. I. Vaireanu; S. I. Voicu; G. Nechifor

2009-01-01

319

Chemical Composition of Abaca (Musa textilis) Leaf Fibers Used for Manufacturing of High Quality Paper Pulps  

Microsoft Academic Search

The chemical composition of leaf fibers of abaca (Musa textilis), which are commonly used for high- quality paper pulp production, was thoroughly studied. The results revealed that the lignin content was 13.2% of the total fiber. The analysis of abaca fibers by pyrolysis coupled to gas chromatography- mass spectrometry (Py-GC\\/MS) released predominantly compounds arising from lignin and p- hydroxycinnamic acids,

DEL RIÄO; ANA GUTIE Ä RREZ

320

Chemical etch studies of Ag\\/n-Si metal–semiconductor composite films  

Microsoft Academic Search

The 2.5-?m-thick Ag\\/n-Si composite films were prepared by magnetron co-sputtering Ag and n-type Silicon targets on Si(111) substrates that were held at 400 °C during deposition. They were then treated with chemical etchants to remove the film of segregated Ag particles in the surface layer. This process was required in order to measure the electronic transport properties of the unsegregated

Ibrahima Diagne; Juan White; Mandoye Ndoye; Clayton W. Bates; W. Robert Thurber

2005-01-01

321

Nanotubules on plant surfaces: Chemical composition of epicuticular wax crystals on needles of Taxus baccata L  

Microsoft Academic Search

Needles of Taxus baccata L. were covered with tubular epicuticular wax crystals varying in diameters (100 and 250nm) and lengths (300–500 and 500–1000nm) on the abaxial and adaxial surfaces, respectively. Various sampling protocols were employed to study the chemical composition of the needle waxes on three different levels of spatial resolution. First, a dipping extraction of whole needles yielded the

Miao Wen; Christopher Buschhaus; Reinhard Jetter

2006-01-01

322

Chromite in the Platreef (Bushveld Complex, South Africa): occurrence and evolution of its chemical composition  

Microsoft Academic Search

The regional distribution and chemical composition of massive and disseminated chromitites through a Platreef sequence and\\u000a along a strike distance of over ?20 km were investigated to correlate them both within the framework of the northern limb\\u000a and to the eastern and western limbs of the Bushveld Complex. The chromitite layers and seams of the Platreef form two main\\u000a chromite-bearing zones:

Marina A. Yudovskaya; Judith A. Kinnaird

2010-01-01

323

The Effect of Dietary Fat Inclusion on Growth, Carcass Characteristics, and Chemical Composition of Rabbits1  

Microsoft Academic Search

Two hundred ten Californian × New Zealand White rabbits were used to study the influence of diet and slaughter weight (2.0, 2.25, and 2.5 kg) on feed intake, growth, feed efficiency, carcass characteristics, and body chemical composition. Seven diets were formulated to contain 24% ADF: Diet C (control) had no added fat; Diets T, O, and S contained 3% of

C. Fernandez; M. J. Fraga

2010-01-01

324

Electrical conductivity of chemically modified multiwalled carbon nanotube\\/epoxy composites  

Microsoft Academic Search

The electrical conductivity of oxidized multiwalled carbon nanotubes (MWNT)\\/epoxy composites is investigated with respect to the chemical treatment of the MWNT. The oxidation is carried out by refluxing the as-received MWNT in concentrated HNO3 and H2O2\\/NH4OH solutions, respectively, under several different treatment conditions. The oxidized MWNT are negatively charged and functionalized with carboxylic groups by both solutions. The MWNT oxidized

Yoon Jin Kim; Taek Sun Shin; Hyung Do Choi; Jong Hwa Kwon; Yeon-Choon Chung; Ho Gyu Yoon

2005-01-01

325

Effect of outdoor conditions on growth rate and chemical composition of Gelidium crinale in culture  

Microsoft Academic Search

A comprehensive study of the major environmental factors affecting growth and chemical composition of Gelidium crinale is presented here for the first time. The purpose of this study was to analyze the significance of the major growth factors\\u000a and to formulate them into regression models. For this purpose summer and winter experiments were conducted in small aerated\\u000a seawater tanks under

Areen Boulus; Ehud Spaneir; Michael Friedlander

2007-01-01

326

Single particle measurements of the chemical composition of cirrus ice residue during CRYSTAL-FACE  

Microsoft Academic Search

The first real-time, in situ, investigation of the chemical composition of the residue of cirrus ice crystals was performed during July 2002. This study was undertaken on a NASA WB-57F high-altitude research aircraft as part of CRYSTAL-FACE, a field campaign which sought to further our understanding of the relation of clouds, water vapor, and climate by characterizing, among other parameters,

D. J. Cziczo; D. M. Murphy; P. K. Hudson; D. S. Thomson

2004-01-01

327

Chemical composition, antibacterial and antifungal activities of Trichoderma sp. growing in Tunisia  

Microsoft Academic Search

Trichoderma species are common soil-inhabiting fungi that have been developed as effective biocontrol agents against various phytopathogenic\\u000a microorganisms. The chemical composition of butanolic extract prepared from cultivatedTrichoderma sp. was analysed using GC-FID and GC-MS. Six components were identified. Limonene, the terpenoid compound, was found to be\\u000a the major component in the tested extract (92.6%). Antibacterial and antifungal activities were also

Fethi Bel Haj Khethr; Samia Ammar; Dhouha Saïdana; Majda Daami; Jihane Chriaa; Kaouthar Liouane; Mohamed Ali Mahjoub; Ahmed Noureddine Helal; Zine Mighri

2008-01-01

328

Chemical warfare  

PubMed Central

Leaf-cutting ants are well known for their highly complex social organization, which provides them with a strong defense against parasites invading their colonies. Besides this attribute, these insects have morphological, physiological and structural characteristics further reinforcing the defense of their colonies. With the discovery of symbiotic bacteria present on the integument of leaf-cutting ants, a new line of defense was proposed and considered to be specific for the control of a specialized fungal parasite of the ants’ fungus gardens (Escovopsis). However, recent studies have questioned the specificity of the integumental bacteria, as they were also found to inhibit a range of fungi, including entomopathogens. The microbiota associated with the leaf-cutting ant gardens has also been proposed as another level of chemical defense, protecting the garden from parasite invasion. Here we review the chemical defense weaponry deployed by leaf-cutting ants against parasites of their fungus gardens and of the ants themselves.

Samuels, Richard Ian; Mattoso, Thalles Cardoso; Moreira, Denise D.O.

2013-01-01

329

Single particle measurements of the chemical composition of cirrus ice residue during CRYSTAL-FACE  

NASA Astrophysics Data System (ADS)

The first real-time, in situ, investigation of the chemical composition of the residue of cirrus ice crystals was performed during July 2002. This study was undertaken on a NASA WB-57F high-altitude research aircraft as part of CRYSTAL-FACE, a field campaign which sought to further our understanding of the relation of clouds, water vapor, and climate by characterizing, among other parameters, anvil cirrus formed about the Florida peninsula. A counter flow virtual impactor (CVI) was used to separate cirrus ice from the unactivated interstitial aerosol particles and evaporate condensed-phase water. Residual material, on a crystal-by-crystal basis, was subsequently analyzed using the NOAA Aeronomy Laboratory's Particle Analysis by Laser Mass Spectrometry (PALMS) instrument. Sampling was performed from 5 to 15 km altitude and from 12° to 28° north latitude within cirrus originating over land and ocean. Chemical composition measurements provided several important results. Sea salt was often incorporated into cirrus, consistent with homogeneous ice formation by aerosol particles from the marine boundary layer. Size measurements showed that large particles preferentially froze over smaller ones. Meteoritic material was found within ice crystals, indicative of a relation between stratospheric aerosol particles and tropospheric clouds. Mineral dust was the dominant residue observed in clouds formed during a dust transport event from the Sahara, consistent with a heterogeneous freezing mechanism. These results show that chemical composition and size are important determinants of which aerosol particles form cirrus ice crystals.

Cziczo, D. J.; Murphy, D. M.; Hudson, P. K.; Thomson, D. S.

2004-02-01

330

Chemical composition and lipoxygenase activity in soybeans (Glycine max L. Merr.) submitted to gamma irradiation  

NASA Astrophysics Data System (ADS)

Soybeans are an important food due to their functional and nutritional characteristics. However, consumption by western populations is limited by the astringent taste of soybeans and their derivatives which results from the action of lipoxygenase, an enzyme activated during product processing. The aim of this study was to evaluate the effect of gamma irradiation on the chemical composition and specific activity of lipoxygenase in different soybean cultivars. Soybeans were stored in plastic bags and irradiated with doses of 2.5, 5 and 10 kGy. The chemical composition (moisture, protein, lipids, ashes, crude fiber, and carbohydrates) and lipoxygenase specific activity were determined for each sample. Gamma irradiation induced a small increase of protein and lipid content in some soybean cultivars, which did not exceed the highest content of 5% and 26%, respectively, when compared to control. Lipoxygenase specific activity decreased in the three cultivars with increasing gamma irradiation dose. In conclusion, the gamma irradiation doses used are suitable to inactivate part of lipoxygenase while not causing expressive changes in the chemical composition of the cultivars studied.

Barros, Érica Amanda de; Broetto, Fernando; Bressan, Dayanne F.; Sartori, Maria M. P.; Costa, Vladimir E.

2014-05-01

331

Effects of substrate temperature on morphology, structure and chemical composition of Cu2S films  

NASA Astrophysics Data System (ADS)

Cu2S thin films have been deposited on CdS/ITO (In2O3:Sn) substrates with various substrate temperatures by DC magnetron sputtering method. The effects of substrate temperature on the crystallization behavior and morphology are studied. Chemical composition of the films is confirmed by energy dispersive X-ray (EDX) spectroscopy. X-ray diffraction (XRD) analysis of the films reveals they have polycrystalline chalcocite structure with (110) texture. Field emission scanning electron microscopy (FESEM) show the crystalline nature of the films at higher substrate temperature, which is in accordance with XRD measurements. Stoichiometric analysis exhibits element composition with Cu/S concentrations ratio equal to 2 approximately.

Ren, Bing; Huang, Jian; Wang, Lin; Tang, Ke; Qin, Kaifeng; Pan, Zhangmin; Wang, Linjun; Xia, Yiben

2013-12-01

332

Initial investigations of the composition of GJ1214b using a chemical column model  

NASA Astrophysics Data System (ADS)

We present initial investigations of the chemical composition of hot, Low Mass Low Density planets. Using a recently-developed column model having a straightforward chemistry scheme (incorporating only C, H, O and N species) as a first step which employs gas-phase rate coefficients valid over a wide temperatures range we input planetary properties for GJ1214-b. We then vary the bulk gas from a pure steam (water)-atmosphere to a solar-type (molecular hydrogen and helium dominated) atmosphere and investigate associated compositional changes e.g. in active minor species such as hydrogen- and nitrogen-oxides.

Grenfell, John Lee; Cabrera, Juan; von Paris, Philip; Stracke, Barbara; Godolt, Mareike; Rauer, Heike

2014-05-01

333

Effect of chemical composition and superheat on macrostructure of high Cr white iron castings  

SciTech Connect

White cast irons are frequently used in applications requiring high wear resistance. High Cr white cast irons have a composite microstructure composed of hard (Fe,Cr)7C3 carbides in a steel matrix. Previous research has indicated that the equiaxed region of these high Cr white iron castings is much more wear resistant under high stress abrasive conditions than the columnar region, when the carbides are oriented perpendicular to the wear surface. In the present study, the effect of both the chemical composition, particularly carbon content, and the pouring superheat of the melt on the macrostructure of high Cr white iron castings is investigated.

Dogan, Omer N.

2005-08-01

334

Chemical composition and antibacterial activity of essential oils from Thymus spinulosus Ten. (Lamiaceae).  

PubMed

The chemical composition of essential oils from aerial parts of Thymus spinulosus Ten. (Lamiaceae) is reported. Four oils from plants growing in different environmental conditions were characterized by GC and GC-MS methods; the oils seem to indicate a new chemotype in the genus Thymus. Influences of soil and altitude characteristics on the essential oil composition are discussed. The oils showed antibacterial activity against Gram-positive (Staphylococcus aureus, Streptococcus faecalis, Bacillus subtilis, and Bacillus cereus) and Gram-negative (Proteus mirabilis, Escherichia coli, Salmonella typhimuium Ty2, and Pseudomonas aeruginosa) bacteria. PMID:12797754

De Feo, Vincenzo; Bruno, Maurizio; Tahiri, Bochra; Napolitano, Francesco; Senatore, Felice

2003-06-18

335

Development of chemical vapor composite (CVC) ceramic materials. Status report, April 1995--June 1997  

SciTech Connect

The objective of the 94 DOE Chemical Vapor Composites (CVC) ceramics materials grant is to develop a reliable and flexible process to produce, in a single step, ceramic composites to final shape. This report is a brief summary of activities in the development of the CVC ceramics materials. Equipment has been designed and built to fabricate CVC silicon carbides with fibers such as Nextel, Nicalon, and carbon. Materials and shapes have been fabricated and characterized as to physical and mechanical properties and microstructure. Details will be given in the final report.

NONE

1997-07-25

336

Chemical composition of the fixed and volatile oils of Nigella sativa L. from Iran.  

PubMed

The chemical composition of the extracted fixed oil (total fatty acid composition) and volatile oil of Nigella sativa L. seeds grown in Iran were determined by GC and GC/MS. Eight fatty acids (99.5%) and thirty-two compounds (86.7%) have been identified in the fixed and volatile oils, respectively. The main fatty acids of the fixed oil were linoleic acid (55.6%), oleic acid (23.4%), and palmitic acid (12.5%). The major compounds of the volatile oil were trans-anethole (38.3%), p-cymene (14.8%), limonene (4.3%), and carvone (4.0%). PMID:14577620

Nickavar, Bahman; Mojab, Faraz; Javidnia, Katayoun; Amoli, Mohammad Ali Roodgar

2003-01-01

337

X-ray Tomographic Study of Chemical Vapor Infiltration Processing of Ceramic Composites.  

PubMed

The fabrication of improved ceramic-matrix composites will require a better understanding of processing variables and how they control the development of the composite microstructure. Noninvasive, high-resolution methods of x-ray tomography have been used to measure the growth of silicon carbide in a woven Nicalon-fiber composite during chemical vapor infiltration. The high spatial resolution allows one to measure the densification within individual fiber tows and to follow the closure of macroscopic pores in situ. The experiments provide a direct test of a recently proposed model that describes how the surface area available for matrix deposition changes during infiltration. The measurements indicate that this surface area is independent of the fiber architecture and location within the preform and is dominated by large-scale macroporosity during the final stages of composite consolidation. The measured surface areas are in good agreement with the theoretical model. PMID:17746112

Kinney, J H; Breunig, T M; Starr, T L; Haupt, D; Nichols, M C; Stock, S R; Butts, M D; Saroyan, R A

1993-05-01

338

X-ray tomographic study of chemical vapor infiltration processing of ceramic composites  

SciTech Connect

The fabrication of improved ceramic-matrix composites will require a better understanding of processing variables and how they control the development of the composite microstructure. Noninvasive, high-resolution methods of x-ray tomography have been used to measure the growth of silicon carbide in a woven Nicalon-fiber composite during chemical vapor infiltration. The high spatial resolution allows one to measure the densification within individual fiber tows and to follow the closure of macroscopic pores in situ. The experiments provide a direct test of a recently proposed model that describes how the surface area available for matrix deposition changes during infiltration. The measurements indicate that this surface area is independent of the fiber architecture and location within the preform and is dominated by large-scale macroporosity during the final stages of composite consolidation. The measured surface areas are in good agreement with the theoretical model. 12 refs., 4 figs.

Kinney, J.H.; Haupt, D.; Saroyan, R.A. (Lawrence Livermore National Lab., CA (United States)); Breunig, T.M.; Nichols, M.C. (Sandia National Laboratories, Livermore, CA (United States)); Starr, T.L.; Stock, S.R.; Butts, M.D. (Georgia Inst. of Technology, Atlanta (United States))

1993-05-07

339

Ultrafine-microstructure composites prepared by chemical vapor deposition. Annual report, January-December 1987  

SciTech Connect

The goal is to develop an analytical model that predicts the experimental conditions that permit the preparation of ultrafine-microstructure ceramic composites by chemical vapor deposition (CVD). The model is to be based on classical thermodynamics, mass transport, kinetic, nucleation, and growth theory. The model will be validated for two dispersed-phase composite systems. One system will be boron nitride plus aluminum nitride; the other hafnium diboride plus silicon carbide. The BN + AlN system is of interest for radomes, windows, and tribological applications while HfB2 + SiC offers potential as a high-temperature oxidation-resistant material including oxidation protective coatings for carbon-carbon composites. Thermodynamic analyses of the BN + AlN and the HfB/sub 2/ + SiC systems were completed. These computerized studies indicate that both composite systems can be prepared by codeposition using commercially available, conventional reagents.

Lackey, W.J.; Freeman, G.B.; Smith, A.W.; Thompson, J.R.; Gerard, G.J.

1987-12-01

340

Wintertime chemical composition of aerosols at a rural location in the Indo-Gangetic Plains  

NASA Astrophysics Data System (ADS)

Systematic measurements of mass concentration and chemical composition of aerosols have been carried out at Kharagpur in the Indo-Gangetic Plains during winter to identify the major sources over the region and to examine the changes in aerosol characteristics during haze events. Aerosol concentration is significantly large at the site, more than two-fold that of the National Ambient Air Quality Standards for residential areas in India. The main sources of aerosols over the region are anthropogenic activities and mineral dust. Species like SO42-, NO3-, NH4+, BC, Cl-, etc. are associated with anthropogenic sources, while Al, Fe, Ca, Na, Ti, Mn, etc. originate mainly from crustal sources. Though the site is only ˜100 km away from the Bay of Bengal, oceanic contribution is insignificant (˜2%), mainly due to prevailing north/northeasterly winds. A mean chemical composition evolved for the location shows that the aerosol system is composed of 17% mineral dust, 18% water-soluble components, 6% black carbon and 23% particulate organic matter along with a residual fraction of 36%. This residual fraction is attributed to organic aerosols of natural or secondary origin and water content of aerosols. An uncertainty of the order of 6-45% is involved in these estimations. Nevertheless, this mean chemical composition can act as a realistic input chemical model in the estimation of aerosol radiative forcing for this region. Analysis indicates that anthropogenic influence can be comparable to or exceeds natural aerosols at the location. The total aerosol mass concentration as well as that of anthropogenic species revealed enhancement on hazy days.

George, Susan K.; Nair, Prabha R.; Parameswaran, K.; Jacob, Salu

2011-08-01

341

Modeling the Chemical Composition of the Fluid that Formed the ALH84001 Carbonates  

NASA Astrophysics Data System (ADS)

The character of aqueous systems on Mars can provide us with important information regarding the history of water and the possibilities for the presence of life on Mars. Evidence of these aqueous systems has been preserved in carbonates found in the martian meteorite ALH84001 whose crystallization age of 4.5 Ga indicates that it has experienced almost all of Mars' history. In addition, the 3.9 Ga age of the carbonates places their formation at a critical time that has been argued to have been `warm and wet' by many studies. The carbonates in the ALH84001 meteorite provide the best opportunity, among all of the martian meteorites, to understand the details of an ancient aqueous system on Mars. Their unique chemical, isotopic and mineralogical composition provides the opportunity to make conclusive statements about the geological conditions in which they formed including the temperature, association with the atmosphere, chemistry of the fluids, and the presence or absence of life. This study uses an empirical model to understand the attributes of the formation fluid based on the unique chemical compositions of the carbonates. This requires the assumption that the ALH84001 carbonate globules formed from a single fluid whose chemical composition changed due to the precipitation of carbonates more calcium rich than the overall fluid composition. The model consists of a simple stepwise stoichiometric calculation of the precipitation of the ALH84001 carbonates from a hypothetical solution. From extensive measurements of the chemical composition of the globules and their abundance in the rock, one can calculate the total amount of magnesium, calcium, and iron removed from the formation fluid as the carbonates precipitated. The unique zoned nature of the ALH84001 carbonates provides a real constraint on the possible fluid compositions consistent with their precipitation. Our results indicate that the fluid that formed the ALH84001 carbonates had an Mg/Ca ratio that was greater than about 4, and an Fe/Ca ratio that was greater than about 1. These elemental ratios are consistent with a fluid that had interacted with Mg-rich ultramafic rock and was reducing enough to retain significant amounts of dissolved iron. ALH84001 is a magnesium rich ultramafic rock, however, it shows no sign of having undergone any kind of dissolution or weathering besides the precipitation of the carbonates. Therefore, it is possible that the fluid interacted with a host-rock of similar composition to ALH84001 located elsewhere prior to precipitating the carbonates in ALH84001.

Niles, P. B.; Leshin, L.

2005-12-01

342

Phylogenetic or environmental control on the organo-chemical composition of Sphagnum mosses?  

NASA Astrophysics Data System (ADS)

Decomposition of organic material is one of the key processes that determines the size of the soil-feedback to global warming, but it is also a process surrounded with one of the largest uncertainties, making understanding its mechanistic drivers of crucial importance. In organic soils decomposition is closely determined by the organo-chemical composition of the litter entering the soil. But what, in turn drives the organo-chemical composition? Is it an emergent feature of the environment the species producing the litter grow in, or is it an evolutionary trait that can be tracked through the species' phylogeny? We set out to answer this question for one of the most import peat-forming plants on earth: the genus Sphagnum. We sampled 18 Sphagnum species, about equally distributed over 6 sites spanning a wide range of environmental conditions: most species were collected at multiple sites. For all species we characterised the chemical composition, focussing on three functional chemistry groups: (i) mineral elements, (ii) carbohydrate polymers (iii) non-carbohydrate polymers (aromatic and aliphatic compounds) . For each group of compounds we used multivariate statistical techniques to derive the degree of variation explained by environment: (site, position within site) and phylogeny (sections within genus Sphagnum). We found that the variation in mineral element concentrations was mostly explained by environment, with the biggest differences in the concentrations of basic cat-ions calcium and magnesium. In contrast, the variation in carbohydrates was mostly explained by phylogeny, with clear associations between sections and monosaccharides. The monosaccharide rhamnose was associated with species from the Acutifolia section known for their poor degradability, whereas xylose and galactose were closely associated with degradable species from the Cuspidata section. The composition non-carbohydrate polymers took an intermediate position: both environment and phylogeny explained a significant part of the variation. We conclude that organo-chemical composition a function of both environment and phylogeny, but that the relative importance of these drivers depends on the type of compounds studied. Environment mainly drives the mineral element composition and a large part of the non-carbohydrate polymer composition, whereas phylogeny drives the variation in carbohydrate polymers. In our presentation we discuss the implications of our findings for carbon accumulation in peatlands and decomposition processes in general.

Limpens, Juul; Nilsson, Mats

2014-05-01

343

Polypyrrole and its composites with 3A zeolite and polyamide 6 as sensors for four chemicals in lacquer thinner  

Microsoft Academic Search

This work is an attempt to search for highly selective sensing elements for the chemical vapors in lacquer thinner. Chemically synthesized polypyrrole (PPy) and PPy composites with 3A zeolite (3A) and polyamide 6 (PA): i.e. PPy_3A50 pellet, PA20_PPy13_3A50 film, and PA20_PPy13_3A50 electrospun fiber bundle have been investigated as the sensing materials for four chemical vapors that are the common components

Ladawan Wannatong; Anuvat Sirivat

2008-01-01

344

Chemical composition and bioactivity of different oregano (Origanum vulgare) extracts and essential oil.  

PubMed

BACKGROUND: There is a growing interest in industry to replace synthetic chemicals by natural products with bioactive properties. Aromatic plants are excellent sources of bioactive compounds that can be extracted using several processes. As far as oregano is concerned, studies are lacking addressing the effect of extraction processes in bioactivity of extracts. This study aimed to characterise the in vitro antioxidant and antibacterial properties of oregano (Origanum vulgare) essential oil and extracts (in hot and cold water, and ethanol), and the chemical composition of its essential oil. RESULTS: The major components of oregano essential oil were carvacrol, ?-fenchyl alcohol, thymol, and ?-terpinene. Hot water extract had the strongest antioxidant properties and the highest phenolic content. All extracts were ineffective in inhibiting the growth of the seven tested bacteria. In contrast, the essential oil inhibited the growth of all bacteria, causing greater reductions on both Listeria strains (L. monocytogenes and L. innocua). CONCLUSION: O. vulgare extracts and essential oil from Portuguese origin are strong candidates to replace synthetic chemicals used by the industry. © 2013 Society of Chemical Industry. PMID:23553824

Teixeira, Bárbara; Marques, António; Ramos, Cristina; Serrano, Carmo; Matos, Olívia; Neng, Nuno R; Nogueira, José M F; Saraiva, Jorge Alexandre; Nunes, Maria Leonor

2013-02-01

345

Some General Laws of Chemical Elements Composition Dynamics in the Hydrosphere  

NASA Astrophysics Data System (ADS)

The biophysical oceanic composition is a result of substance migration and transformation on river-sea and ocean- atmosphere boundaries. Chemical composition of oceanic water is a fundamental multi-dimensional constant for our planet. Detailed studies revealed three types of chemical element distribution in the ocean: 1) Conservative: concentration normalized to salinity is constant in space and time; 2) Nutrient-type: element concentration in the surface waters decreases due to the biosphere consumption; and 3) Litho-generative: complex character of distribution of elements, which enter the ocean with the river runoff and interred almost entirely in sediments (Fig. 1). The correlation between the chemical compositions of the river and oceanic water is high (r = 0.94). We conclude that biogeochemical features of each element are determined by the relationship between its average concentration in the ocean and the intensity of its migration through hydrosphere boundary zones. In Fig.1 we show intensities of global migration and average concentrations in the ocean in the coordinates lgC - lg ?, where C is an average element concentration and ? is its residual time in the ocean. Fig. 1 shows a relationship between three main geochemical parameters of the dissolved forms of chemical elements in the hydrosphere: 1) average concentration in the ocean, 2) average concentration in the river runoff and 3) the type of distribution in oceanic water. Using knowledge of two of these parameters, it allows gaining theoretical knowledge of the third. The System covers all chemical elements for the entire range of observed concentrations. It even allows to predict the values of the annual river transport of dissolved Be, C, N, Ge, Tl, Re, to refine such estimates for P, V, Zn, Br, I, and to determine the character of distribution in the ocean for Au and U. Furthermore, the System allowed to estimate natural (unaffected by anthropogenic influence) mean concentrations of elements in the river runoff and use them as ecological reference data. Finally, due to the long response time of the ocean, the mean concentrations of elements and patterns of their distribution in the ocean can be used to determine pre-technogenic concentrations of elements in the river runoff. An example of such studies for the Northern Eurasia Arctic Rivers will be presented at the conference. References Korzh 1974: J. de Recher. Atmos, 8, 653-660. Korzh 2008: J. Ecol., 15, 13-21. Korzh 2012: Water: Chem. & Ecol., No. 1, 56-62; Fig.1. The System of chemical elements distribution in the hydrosphere. Types of distribution in the ocean: 1) conservative; 2) nutrient-type; 3) litho-generative.

Korzh, V.

2012-12-01

346

Chemical Separations  

NSDL National Science Digital Library

This site contains complete notes in a PowerPoint-like presentation for a chemical separations course. It covers a wide variety of topics, including distillation, extraction, gas chromatography, liquid chromatograpy, chromatography theory, instrumentation, electrophoresis, field flow fractionation, and affinity chromatography. It covers these topics thoroughly using a clear, consistent, and simple presentation style. Links to major topics like GC, LC, and electrophoresis provide specific information about the theory, instrumentation, and practice related to these techniques. The site also contains many annimations illustrating important separation processes.

2011-05-18

347

Chemical composition, nutritional and antioxidant properties of the red edible seaweed Porphyra columbina.  

PubMed

Abstract Proximate composition, fatty acids and amino acid profiles and nutritional (chemical score, protein digestibility, PDCAAS and mineral dialyzability) and antioxidant properties (TEAC, DPPH and power reduction) from Porphyra columbina were evaluated. Total dietary fiber (48.02?±?1.13?g/100?g dry weight) and protein (24.61?±?0.21?g/100?g dry weight) were the two most abundant components in this seaweed. The main saturated and unsaturated fatty acids were C16:0 and C20:5 (n-3), respectively. The limiting amino acid was tryptophan with a chemical score of 57%. Protein digestibility was 74.33?±?3.0%. Porphyra columbina has high mineral content with good Na/K relationship and medium value of potential mineral accessibility (P, Ca and Zn dializability: 18.75?±?0.01, 17.62?±?0.16 and 16.70?±?0.44, respectively). The highest antioxidant properties were obtained with an acetone/water extraction system. This work provides important information about chemical composition and nutraceutical new properties of P. columbina. PMID:24219228

Cian, Raúl E; Fajardo, María A; Alaiz, Manuel; Vioque, Javier; González, Rolando J; Drago, Silvina R

2014-05-01

348

Subsurface Water Oceans on Icy Satellites: Chemical Composition and Exchange Processes  

NASA Astrophysics Data System (ADS)

The state of knowledge about the structure and composition of icy satellite interiors has been significantly extended by combining direct measurements from spacecraft, laboratory experiments, and theoretical modeling. The existence of potentially habitable liquid water reservoirs on icy satellites is dependent on the radiogenic heating of the rock component, additional contributions such as the dissipation of tidal energy, the efficiency of heat transfer to the surface, and the presence of substances that deplete the freezing point of liquid water. This review summarizes the chemical evolution of subsurface liquid water oceans, taking into account a number of chemical processes occuring in aqueous environments and partly related to material exchange with the deep interior. Of interest are processes occuring at the transitions from the liquid water layer to the ice layers above and below, involving the possible formation of clathrate hydrates and high-pressure ices on large icy satellites. In contrast, water-rock exchange is important for the chemical evolution of the liquid water layer if the latter is in contact with ocean floor rock on small satellites. The composition of oceanic floor deposits depends on ambient physical conditions and ocean chemistry, and their evolutions through time. In turn, physical properties of the ocean floor affect the circulation of oceanic water and related thermal effects due to tidally-induced porous flow and aqueous alteration of ocean floor rock.

Sohl, Frank; Choukroun, Mathieu; Kargel, Jeffrey; Kimura, Jun; Pappalardo, Robert; Vance, Steve; Zolotov, Mikhail

2010-06-01

349

Source apportionment of Baltimore aerosol from combined size distribution and chemical composition data  

NASA Astrophysics Data System (ADS)

Several multivariate data analysis methods have been applied to a combination of particle size and composition measurements made at the Baltimore Supersite. Partial least squares (PLS) was used to investigate the relationship (linearity) between number concentrations and the measured PM2.5 mass concentrations of chemical species. The data were obtained at the Ponca Street site and consisted of six days' measurements: 6, 7, 8, 18, 19 July, and 21 August 2002. The PLS analysis showed that the covariance between the data could be explained by 10 latent variables (LVs), but only the first four of these were sufficient to establish the linear relationship between the two data sets. More LVs could not make the model better. The four LVs were found to better explain the covariance between the large sized particles and the chemical species. A bilinear receptor model, PMF2, was then used to simultaneously analyze the size distribution and chemical composition data sets. The resolved sources were identified using information from number and mass contributions from each source (source profiles) as well as meteorological data. Twelve sources were identified: oil-fired power plant emissions, secondary nitrate I, local gasoline traffic, coal-fired power plant, secondary nitrate II, secondary sulfate, diesel emissions/bus maintenance, Quebec wildfire episode, nucleation, incinerator, airborne soil/road-way dust, and steel plant emissions. Local sources were mostly characterized by bi-modal number distributions. Regional sources were characterized by transport mode particles (0.2- 0.5?m).

Ogulei, David; Hopke, Philip K.; Zhou, Liming; Patrick Pancras, J.; Nair, Narayanan; Ondov, John M.

350

Propolis from northern California and Oregon: chemical composition, botanical origin, and content of allergens.  

PubMed

Propolis is a beehive product that bees manufacture by mixing their own wax with vegetable resins collected from different species of trees and bushes. The chemical composition of propolis is very variable because it depends on the flora locally available, and specimens from different geographical and climatic areas display unique properties. In this paper, the results of the chemical characterization of some propolis specimens collected in northern California and in Oregon are presented. Their chemical compositions show that all specimens contain resins from poplars of the Tacamahaca section (balsam poplars)--characteristic of the western part of the North American continent. Nevertheless, some of the specimens are of mixed origin because they also contain resins from poplars of the Aigeiros section (cottonwoods)--also present in this part of the world. Propolis causes allergies in sensitive human individuals, which are due to the presence of certain esters. The contents of known propolis allergenic esters--phenylethyl caffeate, 1,1-dimethylallyl caffeate, benzyl cinnamate, and benzyl salicylate--have been investigated in these specimens and found to depend on the botanical origin. PMID:24772818

Aliboni, Andrea

2014-01-01

351

Chemical composition changes in eucalyptus and pinus woods submitted to heat treatment.  

PubMed

This study investigated the influence of heat treatment on the chemical composition of Eucalyptus saligna and Pinus caribaea var. hondurensis woods to understand its role in wood processing. E. saligna and P. caribaea var. hondurensis woods were treated in a laboratorial electric furnace at 120, 140, 160 and 180 degrees C to induce their heat treatment. The chemical composition of the resulting products and those from original wood were determined by gas chromatography. Eucalyptus and Pinus showed a significant reduction in arabinose, manose, galactose and xylose contents when submitted to increasing temperatures. No significant alteration in glucose content was observed. Lignin content, however, increased during the heat process. There was a significant reduction in extractive content for Eucalyptus. On the other hand, a slight increase in extractive content has been determined for the Pinus wood, and that only for the highest temperature. These different behaviors can be explained by differences in chemical constituents between softwoods and hardwoods. The results obtained in this study provide important information for future research and utilization of thermally modified wood. PMID:18586488

Brito, J O; Silva, F G; Leão, M M; Almeida, G

2008-12-01

352

Chemical composition of interstellar molecular clouds: a millimeter and submillimeter spectral line survey of OMC-1  

SciTech Connect

Results are presented from a millimeter and submillimeter spectral line survey of the core of the Orion molecular cloud (OMC-1). The millimeter-wave survey, conducted at the Owens Valley Radio Observatory (OVRO), covers a 55 GHz interval in 1.3 mm (23 GHz) atmospheric window and contains emission from 29 molecules. Together with the frequency selective submillimeter observations of H/sub 2/D/sup +/ (372.4 GHz), Cl(492.2 GHz), NH/sub 3/ (572.5 GHz), and HCl (625.9 GHz) performed from the NASA Kuiper Airborne Observatory, over 800 emission lines have been detected from 33 chemically distinct species during the course of this work. The uniformly calibrated results from the unique and extensive OVRO spectral line survey place significant constraints on models of interstellar chemistry, and have allowed the chemical composition of the various regions in OMC-1 to be definitively characterized. A global analysis of the observed abundances showed that the markedly different chemical composition of the kinematically distinct Orion subsources may be simply interpreted in the framework of an evolving, initially quiescent, gas phase chemistry influenced by the process of massive star formation.

Blake, G.A.

1986-01-01

353

The effect of natural weathering on the chemical and isotopic compositions of biotites  

USGS Publications Warehouse

The effect of progressive natural weathering on the isotopic (Rb-Sr, K-Ar, ??D, ??18O) and chemical (REE, H2O+) compositions of biotite has been studied on a suite of migmatitic biotites from the Chad Republic. During the early stages of weathering the Rb-Sr system is strongly affected, the hydrogen and oxygen isotope compositions change markedly, the minerals are depleted in light REE, the water content increases by a factor of two, and the K-Ar system is relatively little disturbed. During intensive weathering the K-Ar system is more strongly disturbed than the Rb-Sr system. Most of the isotopic and chemical modifications take place under nonequilibrium conditions and occur before newly formed kaolinite and/or smectite can be detected. These observations suggest that 1. (a) "protominerals" may form within the biotite structure during the initial period of weathering, and 2. (b) only when chemical equilibrium is approached in the weathering profile are new minerals able to form. ?? 1982.

Clauer, N.; O'Neil, J. R.; Bonnot-Courtois, C.

1982-01-01

354

Aging of Secondary Organic Aerosol from ?-Pinene: Changes in Chemical Composition, Density and Morphology  

NASA Astrophysics Data System (ADS)

Biogenic volatile organic compounds (VOC) are emitted in large quantities into the atmosphere. These VOC, which includes ?-pinene, can react to produce secondary organic aerosols (SOA), which contribute to a substantial fraction of ambient organic aerosols and are known to adversely affect visibility, climate and health. Despite this, the current knowledge regarding the SOA composition, their physical properties and the chemical aging processes they undergo in the atmosphere is limited. In this study, chemical aging of SOA generated from the photooxidation of ?-pinene was investigated in the York University smog chamber. The formation and aging of both gas and particle phase products were analyzed using an atmospheric pressure chemical ionization triple quadrupole mass spectrometer. The density of secondary organic matter was also simultaneously measured over the course of the aging experiments, allowing us to improve our understanding in changes in particle composition that may occur. In addition, particle phase and shape was investigated for generated particles from ?-pinene oxidation by scanning electron microscope (SEM). Results of this work, including particle density and morphology will be presented as well as comparisons of gas and particle phase products time profiles during aging.

Sarrafzadeh, M.; Hastie, D. R.

2013-12-01

355

Chemical composition and thermal behavior of five brands of thermoplasticized gutta-percha  

PubMed Central

Objective: The aim of this study was determine the chemical composition and thermal behavior of Thermafil (TH), Microseal Cone (MC), Microseal Microflow (MF), Obtura (OB) and Obtura Flow (OF). In addition, their thermal behavior in response to temperature variations was studied by differential scanning calorimetry (DSC) to determine the temperature at which gutta-percha switches from the beta to alpha form, and from the alpha to the amorphous phase. Materials and Methods: The organic and inorganic fractions were separated by dissolution in chloroform. Gutta-percha (GP) was precipitated with acetone. The inorganic fraction was analyzed via Elemental Microanalysis. Energy Dispersive X-ray Microanalysis and X-ray Diffraction were used to identify the chemical elements and compounds (BaSO4 and ZnO). Thermal analysis was conducted using DSC. Results: The organic and inorganic fractions ranged from 21.3% and 26.9% of weights, respectively. MC and MF showed the highest percentages of organic compounds (P = 0.0125). All specimens exhibited two crystalline transformations when heated from ambient temperature to 130°C. MC presented the highest percentage of GP. Conclusions: No correlation was observed between chemical composition and thermal behavior. Each of the products showed thermal behavior that is typical of beta-phase gutta-percha.

Maniglia-Ferreira, Claudio; Gurgel-Filho, Eduardo Diogo; de Araujo Silva, Joao Batista; de Paula, Regina Celia Monteiro; de Andrade Feitosa, Judith Pessoa; de Sousa-Filho, Francisco Jose

2013-01-01

356

Chemical synthesis of poly(lactic-co-glycolic acid)/hydroxyapatite composites for orthopaedic applications.  

PubMed

Hydroxyapatite-biodegradable polymer composites were synthesized by a colloidal non-aqueous chemical precipitation technique at room temperature. The starting materials used for synthesizing hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) were Ca(NO(3))(2) x 4H(2)O and H(3)PO(4), resulting in single phase HA while poly(d,l-lactic-co-glycolic acid) (PLGA) was used as the biodegradable polymer component. The composites were prepared containing 10, 20, and 30 wt.% HA in the presence of the dissolved polymer without evidence of any visible phase separation of the particulates from the PLGA polymer. In addition, the pH changes occurring in the solution during precipitation, the yield of the ceramic due to the chemical reaction, bonding characteristics between the ceramic and the polymer, the microstructure, tensile strength, and thermal stability of the composites have been investigated. Additional in vitro studies include osteoblast-like adhesion assessment on composites utilizing MG63 cells. The results of these studies are described and discussed. PMID:16701887

Petricca, Sarah E; Marra, Kacey G; Kumta, Prashant N

2006-05-01

357

Crystal Structure and Chemical Composition of a Presolar Silicate from the Queen Elizabeth Range 99177 Meteorite  

NASA Technical Reports Server (NTRS)

Mineral characterization of presolar silicate grains, the most abundant stardust phase, has provided valuable information about the formation conditions in circumstellar environments and in super-nova (SN) outflows. Spectroscopic observations of dust around evolved stars suggest a majority of amor-phous, Mg-rich olivine grains, but crystalline silicates, most of which are pyroxene, have also been observed [1]. The chemical compositions of hundreds of presolar silicates have been determined by Auger spectroscopy and reveal high Fe contents and nonstoichiometric compositions intermediate to olivine and pyroxene [2-6]. The unexpectedly high Fe contents can partly be attributed to secondary alteration on the meteorite parent bodies, as some grains have Fe isotopic anomalies from their parent stellar source [7]. Only about 35 presolar silicates have been studied for their mineral structures and chemical compositions by transmission electron microscopy (TEM). These grains display a wide range of compositions and structures, including crystalline forsterite, crystalline pyroxene, nanocrystalline grains, and a majority of amorphous nonstoichiometric grains. Most of these grains were identified in the primitive Acfer 094 meteorite. Presolar silicates from this meteorite show a wide range of Fe-contents, suggestive of secondary processing on the meteorite parent body. The CR chondrite QUE 99177 has not suffered as much alteration [8] and displays the highest presolar silicate abundance to date among carbonaceous chondrites [3, 6]. However, no mineralogical studies of presolar silicates from this meteorite have been performed. Here we examine the mineralogy of a presolar silicate from QUE 99177.

Nguyen, A. N.; Keller, L. P.; Rahman, Z.; Messenger, S.

2013-01-01

358

The Perils of Partition: Difficulties in Retrieving Magma Compositions from Chemically Equilibrated Basaltic Meteorites  

NASA Technical Reports Server (NTRS)

The chemical compositions of magmas can be derived from the compositions of their equilibrium minerals through mineral/magma partition coefficients. This method cannot be applied safely to basaltic rocks, either solidified lavas or cumulates, which have chemically equilibrated or partially equilibrated at subsolidus temperatures, i.e., in the absence of magma. Applying mineral/ melt partition coefficients to mineral compositions from such rocks will typically yield 'magma compositions' that are strongly fractionated and unreasonably enriched in incompatible elements (e.g., REE's). In the absence of magma, incompatible elements must go somewhere; they are forced into minerals (e.g., pyroxenes, plagioclase) at abundance levels far beyond those established during normal mineral/magma equilibria. Further, using mineral/magma partition coefficients with such rocks may suggest that different minerals equilibrated with different magmas, and the fractionation sequence of those melts (i.e., enrichment in incompatible elements) may not be consistent with independent constraints on the order of crystallization. Subsolidus equilibration is a reasonable cause for incompatible- element-enriched minerals in some eucrites, diogenites, and martian meteorites and offers a simple alternative to petrogenetic schemes involving highly fractionated magmas or magma infiltration metasomatism.

Treiman, Allan H.

1996-01-01

359

Chemical composition of primary cosmic rays with energies around the knee region observed at Mt. Chacaltaya  

NASA Astrophysics Data System (ADS)

The chemical composition of primary cosmic rays around the knee region has been investigated with an air shower array at Mt.Chacaltaya. From 1987 to 1991, we examined observed equi-intensity curves comparing those with a Monte Carlo simulation where the primary composition is assumed to be a mixture of protons and Fe nuclei, and obtained the their mixing ratio as a function of the primary energy(Ogio et al., 2001). Moreover, from 1995 to 1997, we made a measurement of arrival time distributions of air ?Cerenkov light. From an analysis of arrival time distributions of ?Cerenkov light, we obtained the composition as a mixture of proton, He, CNO, Si-Mg, Fe groups(Shirasaki et al., 2001). Both the results show that the average mass number of primary nuclei ln A gradually increases up to ˜ 2 around the knee region and up to ˜ 3 around 1016 eV. In 1999, we improved our array to observe air showers with lower primary energies. Furthermore, we installed five detectors in the array to measure the lateral distribution of air ?Cerenkov light. Now we examine the chemical composition of primary cosmic rays above 5 × 1012 eV more precisely with air ?Cerenkov light data and an equi-intensity curve analysis. References Ogio, S., et al., Il Nuovo Cimento C, 24,2001.(to be published) Shirasaki, Y., et al., Astropart. Phys., 15,241-257, 2001.

Ogio, S.; Yoshii, H.; Tsunesada, Y.; Kakimoto, F.; Tajima, N.; Tokuno, H.; Harada, D.; Kaneko, T.; Shimoda, S.; Morihisa, T.; Kuwata, Y.; Morizawa, A.; Nakamitsu, S.; Okamoto, K.; Burgoa, O.; Kurashina, Y.; Nishi, K.; Murakami, K.; Toyoda, Y.; Matsubara, Y.; Shirasaki, Y.; Kadota, K.; Mizumoto, Y.; Yamada, Y.; Nakatani, H.; Gotoh, E.; Miranda, P.; Velarde, A.

360

Distribution and decline of endangered herbaceous heathland species in relation to the chemical composition of the soil  

Microsoft Academic Search

High atmospheric deposition of ammonium affects the physical and chemical status of the soil, increasing nitrogen availability, soil acidity and the mobilization of toxic metal ions. To investigate whether and how the decline of several herbaceous plant species in Dutch heathlands is associated with these processes, the chemical composition of the soil on which these species grow has been compared

A. L. F. M. Houdijk; P. J. M. Verbeek; H. F. G. VAN DIJK; J. G. M. Roelofs

1993-01-01

361

Chemical composition, in vitro digestibility and antioxidant activity of solid wastes from the fruits of Silybum marianum  

Microsoft Academic Search

äThe chemical composition of solid wastes from Silybum marianum fruits (WSS) and the contents of total polyphenols, total ¿avonoids and antioxidant activity of the extracts from WSS with distilled water, ethanol (40%, 70% and 95%) and methanol was investigated. Chemical analysis indicated that WSS contained high amounts of crude protein (25.58%), calcium, potassium and magnesium. The content of plumbum, selenium

Fang Li; Xiangyang Wu; Ting Zhao; Jiangli Zhao; Feng Li; Liang Han; Liuqing Yang

2011-01-01

362

Influence of particle chemical composition on the phase of cold clouds at a high-alpine site in Switzerland  

Microsoft Academic Search

This paper studies the influence of particle chemical composition on the phase of cold clouds observed during two intensive measurement periods of the Cloud and Aerosol Characterization Experiments conducted at the Jungfraujoch site (Switzerland). Cloud droplets and particles were sampled simultaneously using a suite of optical, chemical, and microphysical instruments connected downstream of a total inlet and an interstitial inlet.

Admir Créso Targino; Hugh Coe; Julie Cozic; Jonathan Crosier; Ian Crawford; Keith Bower; Michael Flynn; Martin Gallagher; James Allan; Bart Verheggen; Ernest Weingartner; Urs Baltensperger; Tom Choularton

2009-01-01

363

Chemical composition of major VOC emission sources in the Seoul atmosphere.  

PubMed

This paper describes a chemical analysis of volatile organic compounds (VOCs) for five emission sources in Seoul. The source categories included motor vehicle exhaust, gasoline evaporation, paint solvents, natural gas and liquefied petroleum gas (LPG). These sources were selected because they have been known to emit significant quantities of VOCs in the Seoul area (more than 5% of the total emission inventory). Chemical compositions of the five emission sources are presented for a group of 45 C2-C9 VOCs. Motor vehicle exhaust profiles were developed by conducting an urban tunnel study. These emissions profiles were distinguished from the other emission profiles by a high weight percentage of butanes over seasons and propane in the wintertime. It was found that this is due to the wide use of butane-fueled vehicles. To obtain gasoline vapor profiles, gasoline samples from five major brands for each season were selected. The brands were blended on the basis of the marketshare of these brands in Seoul area. Raoult's law was used to calculate gasoline evaporative compositions based on the liquid gasoline compositions. The measured and estimated gasoline vapor compositions were found to be in good agreement. Vehicle and gasoline evaporation profiles were made over seasons because of the seasonal change in their compositions. Paint solvent emissions profiles were produced based on a product-use survey and sales figures. These profiles are a composite of four major oil-based paints and thinning solvent. The source profile of natural gas was made on a methane-free basis. It was found that Ethane and propane were the most abundant compounds accounting for 95% of the natural gas composition. LPG was largely composed of propane and ethane and the remaining components were minor contributors. PMID:15006511

Na, Kwangsam; Kim, Yong Pyo; Moon, Il; Moon, Kil-Choo

2004-04-01

364

Quantifying the chemical composition of soil organic carbon with solid-state 13C NMR  

NASA Astrophysics Data System (ADS)

The vulnerability of soil organic carbon (SOC) to biological decomposition and mineralisation to CO2 is defined at least partially by its chemical composition. Highly aromatic charcoal-like SOC components are more stable to biological decomposition than other forms of carbon including cellulose. Solid-state 13C NMR has gained wide acceptance as a method capable of defining SOC chemical composition and mathematical fitting processes have been developed to estimate biochemical composition. Obtaining accurate estimates depends on an ability to quantitatively detect all carbon present in a sample. Often little attention has been paid to defining the proportion of organic carbon present in a soil that is observable in solid-state 13C NMR analyses of soil samples. However, if such data is to be used to inform carbon cycling studies, it is critical that quantitative assessments of SOC observability be undertaken. For example, it is now well established that a significant discrimination exists against the detection of the low proton content polyaromatic structures typical of charcoal using cross polarisation 13C NMR analyses. Such discrimination does not exist where direct polarisation analyses are completed. In this study, the chemical composition of SOC as defined by cross polarisation and direct polarisation13C NMR analyses will be compared for Australian soils collected from under a diverse range of agricultural managements and climatic conditions. Results indicate that where significant charcoal C contents exist, it is highly under-represented in the acquired CP spectra. For some soils, a discrimination against alkyl carbon was also evident. The ability to derive correction factors to compensate for such discriminations will be assessed and presented.

Baldock, J. A.; Sanderman, J.

2011-12-01

365

Chemical spectroscopy  

SciTech Connect

The purpose of chemical spectroscopy with neutrons is to utilize the dependence of neutron scattering cross-sections on isotope and on momentum transfer (which probes the spatial extent of the excitation) to understand fundamental and applied aspects of the dynamics of molecules and fluids. Chemical spectroscopy is divided into three energy ranges: vibrational spectroscopy, 25-500 MeV, for which much of the work is done on Be-filter analyzer instruments; low energy spectroscopy, less than 25 MeV; and high resolution spectroscopy, less than 1 MeV, which typically is performed on backscattering spectrometers. Representative examples of measurements of the Q-depenence of vibrational spectra, higher energy resolution as well as extension of the Q-range to lower values at high energy transfers, and provisions of higher sensitivities in vibrational spectroscopy are discussed. High resolution, high sensitivity, and polarization analysis studies in low energy spectroscopy are discussed. Applications of very high resolution spectroscopy are also discussed. (LEW)

Eckert, J.; Brun, T.O.; Dianoux, A.J.; Howard, J.; Rush, J.J.; White, J.W.

1984-01-01

366

Upper limit to the mass of pulsationally stable stars with uniform chemical composition  

NASA Technical Reports Server (NTRS)

Nuclear-energized pulsational instability is a well-known feature of models of chemically homogeneous stars above a critical mass. With the Rogers-Iglesias opacities, the instability occurs above 120-150 solar mass for normal Galactic Population I chemical compositions, and above approximately 90 solar mass for stars in metal-poor environments like the outer Galaxy and the Small Magellanic Cloud. Models of homogeneous helium-burning stars are unstable above masses of 19 and 14 solar mass, respectively. These significant increases of the critical masses, in the normal metallicity cases, over the values derived previously with the Los Alamos opacities can explain the stability of the brightest observed O-type stars, but they do not exclude the possibility that the most luminous hydrogen-deficient Wolf-Rayet stars are experiencing this type of instability.

Stothers, Richard B.

1992-01-01

367

Process for the preparation of fiber-reinforced ceramic composites by chemical vapor deposition  

DOEpatents

A chemical vapor deposition (CVD) process for preparing fiber-reinforced ceramic composites. A specially designed apparatus provides a steep thermal gradient across the thickness of a fibrous preform. A flow of gaseous ceramic matrix material is directed into the fibrous preform at the cold surface. The deposition of the matrix occurs progressively from the hot surface of the fibrous preform toward the cold surface. Such deposition prevents the surface of the fibrous preform from becoming plugged. As a result thereof, the flow of reactant matrix gases into the uninfiltrated (undeposited) portion of the fibrous preform occurs throughout the deposition process. The progressive and continuous deposition of ceramic matrix within the fibrous preform provides for a significant reduction in process time over known chemical vapor deposition processes.

Lackey, Jr., Walter J. (Oak Ridge, TN); Caputo, Anthony J. (Knoxville, TN) [Knoxville, TN

1986-01-01

368

Chemical composition of Titan’s atmosphere and ionosphere: Observations and the photochemical model  

NASA Astrophysics Data System (ADS)

Basic observational data on hydrocarbons, nitriles, and ions on Titan are compared with predictions of the photochemical model. Uncertainties of the observed abundances and differences between the data from different instruments and observing teams are comparable with the differences between the observations and the model results. Main reactions of production and loss for each species are quantitatively assessed and briefly discussed. Formation of haze by polymerization of hydrocarbons and nitriles and recombination of heavy ions is calculated along with condensation of various species near the tropopause. Overall deposition is a layer of 300 m thick for the age of the Solar System, and nitrogen constitutes 8% of the deposition. The model reproduces the basic observational data and adequately describes basic chemical processes in Titan’s atmosphere and ionosphere. The presented model results and the observational data may be used as a reference to chemical composition of Titan’s atmosphere and ionosphere.

Krasnopolsky, Vladimir A.

2014-07-01

369

Chemical composition and biological activity of the essential oil of Amomum biflorum.  

PubMed

The aim of this study was to investigate the chemical composition and bioactivity of Amomum biflorum Jack harvested in the region of Petchaboon, Thailand. The essential oil of the fresh whole plant obtained by hydrodistillation was analyzed by gas chromatography (GC) (Kovats index) and gas chromatography coupled with mass spectrometry (GC/MS). The average yield of essential oil of A. biflorum was 0.21 +/- 0.05 % (w/w). The major chemical constituents were camphor (17.6 %), alpha-bisabolol (16.0 %), camphene (8.2 %) and alpha-humulene (5.1%). The essential oil was active against Staphylococcus aureus (MIC: 30 microg/mL) and had an antioxidant activity with an ORAC index of 23 +/- 5 micromol Trolox/mg. PMID:23513745

Singtothong, Chakkrapat; Gagnon, Michel J; Legault, Jean

2013-02-01

370

The Cell Wall of Rickettsia mooseri I. Morphology and Chemical Composition1  

PubMed Central

Cell walls prepared by mechanically disrupting intact Rickettsia mooseri (R. typhi) were examined in an electron microscope and analyzed chemically. Electron micrographs of metal-shadowed and negatively stained rickettsial cell walls revealed no significant differences, except for smaller size, from bacterial cell walls prepared in a similar manner. The chemical composition was complex, and resembled that of gram-negative bacterial cell walls more closely than that of gram-positive bacterial cell walls. R. mooseri cell walls contained the sugars, glucose, galactose, and glucuronic acid, the amino sugars, glucosamine, and muramic acid, and at least 15 amino acids. Diaminopimelic acid, a compound hitherto found only in bacteria and blue-green algae, was demonstrated in rickettsiae for the first time. Teichoic acids were not detected. The compounds identified accounted for about 70% of the dry weight of the cell walls. Images

Wood, William H.; Wisseman, Charles L.

1967-01-01

371

Recent Progress of Propolis for Its Biological and Chemical Compositions and Its Botanical Origin  

PubMed Central

Propolis is the generic name given to the product obtained from resinous substances, which is gummy and balsamic and which is collected by bees from flowers, buds, and exudates of plants. It is a popular folk medicine possessing a broad spectrum of biological activities. These biological properties are related to its chemical composition and more specifically to the phenolic compounds that vary in their structure and concentration depending on the region of production, availability of sources to collect plant resins, genetic variability of the queen bee, the technique used for production, and the season in which propolis is produced. Many scientific articles are published every year in different international journal, and several groups of researchers have focused their attention on the chemical compounds and biological activity of propolis. This paper presents a review on the publications on propolis and patents of applications and biological constituents of propolis.

Toreti, Viviane Cristina; Sato, Helia Harumi; Pastore, Glaucia Maria; Park, Yong Kun

2013-01-01

372

[Comparative study of the chemical composition of excrement from some large African herbivorous mammals].  

PubMed

In the course of an ecological and comparative study concerning the beetle and fly communities inhabiting the droppings of some large African grass-eating mammals, we analysed the chemical composition of fresh dung dropped in winter 1977-1978 and in spring 1978. The mammals concerned are : Blesbok (Damaliscus pygargus albifrons Pallas), Impala (Aepyceros melampus Licht.), Bongo (Boocerus euryceros Ogilby), Nyala (Tragelaphus angasi Angas), Eland from Cap (Taurotragus oryx Pallas), Eland of Lloyd Derby (Taurotragus derbianus Gray) and Zebu (Bos indicus Lin). The results of these chemical analysis were treated by a statistical method based upon the different multivariate analysis, largely used in mathematical taxonomy. This method allowed to draw up dendrograms showing the affinities between the different types of excrements. The affinities stated appeared to be related to the systematic position of the species so far studied. PMID:7258040

Nibaruta, G; Desiere, M; Debaere, R

1980-10-01

373

Chemical composition fluctuations in roots of Plumbago scandens L. in relation to floral development.  

PubMed

Plumbago scandens L. is a Brazilian tropical/subtropical species that occurs along the coast. Chemically it is mainly represented by naphthoquinones, flavonoids, terpenoids and steroids. The aim of the present work is to study quantitative changes in the root metabolic production of Plumbago scandens during different physiologic developmental stages relative to floration. The results indicated the presence of four substances in the extracts: plumbagin, epi-isoshinanolone, palmitic acid and sitosterol, independent on developmental stage. The naphthoquinone plumbagin has always showed to be the major component of all extracts. Naphthoquinones exhibited their highest content during floration, while the content of the two others components decreased during this stage, revealing an inverse profile. The chemical composition changed depending on the plant requirements. PMID:22146952

Paiva, Selma R; Lima, Lucilene A; Figueiredo, Maria Raquel; Kaplan, Maria Auxiliadora C

2011-12-01

374

Chemical composition and mass closure of ambient PM10 at urban sites  

NASA Astrophysics Data System (ADS)

The chemical composition of PM10 was studied during summer and winter sampling campaigns conducted at two different urban sites in the city of Thessaloniki, Greece (urban-traffic, UT and urban-industrial, UI). PM10 samples were chemically analysed for minerals (Si, Al, Ca, Mg, Fe, Ti, K), trace elements (Cd, Cr, Cu, Mn, Pb, V, Zn, Te, Co, Ni, Se, Sr, As, and Sb), water-soluble ions (Cl -, NO 3-, SO 42-, Na +, K +, NH 4+, Ca 2+, Mg 2+) and carbonaceous compounds (OC, EC). Spatial variations of atmospheric concentrations showed significantly higher levels of minerals, some trace metals and TC at the UI site, while at the UT site significantly higher levels of elements like Cd, Ba, Sn, Sb and Te were observed. Crustal elements, excepting Ca at the UI site, did not exhibit significant seasonal variations at any site pointing to constant emissions throughout the year. In order to reconstruct the particle mass, the determined components were classified into six classes as follows: mineral matter (MIN), trace elements (TE), organic matter (OM), elemental carbon (EC), sea salt (SS) and secondary inorganic aerosol (SIA). Good correlations with slopes close to 1 were found between chemically determined and gravimetrically measured PM10 masses for both sites. According to the chemical mass closure obtained, the major components of PM10 at both sites were MIN (soil-derived compounds), followed by OM and SIA. The fraction unaccounted for by chemical analysis comprised on average 8% during winter and 15% during summer at the urban-industrial site, while at the urban-traffic site the percentages were 21.5% in winter and 4.8% in summer.

Terzi, Eleni; Argyropoulos, George; Bougatioti, Aikaterini; Mihalopoulos, Nikolaos; Nikolaou, Kostas; Samara, Constantini

2010-06-01

375

Determining the chemical composition of cloud condensation nuclei. Second progress report  

SciTech Connect

This second progress report describes the status of the project one and one-half years after the start. The goal of the project is to develop the instrumentation to collect cloud condensation nuclei (CCN) in sufficient amounts to determine their chemical composition, and to survey the CCN composition in different climates through a series of field measurements. Our approach to CCN collection is to first form droplets on the nuclei under simulated cloud humidity conditions, which is the only known method of identifying CCN from the background aerosol. Under cloud chamber conditions, the droplets formed become larger than the surrounding aerosol, and can then be removed by inertial impaction. The residue of the evaporated droplets represents the sample to be chemically analyzed. Two size functions of CCN particles are collected by first forming droplets on the large particles are collected by first forming droplets on the large CCN in a haze chamber at 100% relative humidity, and then activating the remaining CCN at 1% supersaturation in a cloud chamber. The experimental apparatus is a serious flow arrangement consisting of an impactor to remove the large aerosol particles, a haze chamber to form droplets on the remaining larger CCN, another impactor to remove the haze droplets containing the larger CCN particles for chemical analysis, a continuous flow diffusion (CFD) cloud chamber to form droplets on the remaining smaller CCN, and a third impactor to remove the droplets for the small CCN sample. Progress is documented here on the development of each of the major components of the flow system. Chemical results are reported on tests to determine suitable wicking material for the different plates. Results of computer modeling of various impactor flows are discussed.

Williams, A.L.; Rothert, J.E.; McClure, K.E. [Illinois State Water Survey, Champaign, IL (United States); Alofs, D.J.; Hagen, D.E.; White, D.R.; Hopkins, A.R.; Trueblood, M.B. [Missouri Univ., Rolla, MO (USA). Cloud and Aerosol Science Lab.

1992-02-01

376

Thermal expansion of laminated, woven, continuous ceramic fiber/chemical-vapor-infiltrated silicon carbide matrix composites  

NASA Technical Reports Server (NTRS)

Thermal expansions of three two-dimensional laminate, continuous fiber/chemical-vapor-infiltrated silicon carbide matrix composites reinforced with either FP-Alumina (alumina), Nextel (mullite), or Nicalon (Si-C-O-N) fibers are reported. Experimental thermal expansion coefficients parallel to a primary fiber orientation were comparable to values calculated by the conventional rule-of-mixtures formula, except for the alumina fiber composite. Hysteresis effects were also observed during repeated thermal cycling of that composite. Those features were attributed to reoccurring fiber/matrix separation related to the micromechanical stresses generated during temperature changes and caused by the large thermal expansion mismatch between the alumina fibers and the silicon carbide matrix.

Eckel, Andrew J.; Bradt, Richard C.

1990-01-01

377

Alumina fiber/alumina matrix composites prepared by a chemical vapor infiltration technique  

SciTech Connect

Ceramic/ceramic composites made of alumina fibers embedded in an alumina matrix were obtained from fibrous alumina preforms (fiber volume = 0.12 to 0.40) using a chemical vapor infiltration technique based on gaseous alumina precursors (AlCl3-H2-CO2). Low deposition temperatures (950 to 1000 C) and total pressures (2 to 3 kPa) must be used to preferentially deposit alumina within the pores rather than on the external surface of the preform. Different fiber orientations were studied: i.e. randomly oriented short fibers and one- and two-dimensional preforms. Densification was performed down to residual open porosity of the order of 10 to 15 percent. For a one-dimensional alpha-alumina fiber composite (residual porosity about 10 percent), flexural strengths of 250 MPa and about 100 MPa were obtained at room temperature and 1200 C, respectively. Most composites exhibited brittle failure at room temperature. 20 references.

Colmet, R.; Lhermitte-Sebire, I.; Naslain, R.

1986-04-01

378

Wet chemically grown composite thin film for room temperature LPG sensor  

NASA Astrophysics Data System (ADS)

We have synthesized thin film of zinc oxide-polyaniline (ZnO/PANI) composite using a simple wet chemical approach. As-synthesized ZnO/PANI composite thin film studied using different characterization techniques. The optical study reveals the penetration and interaction of PANI molecules with ZnO thin film. Prominent blue shift in UV-vis due to interaction between ZnO and PANI indicate presence of zinc oxide in polyaniline matrix. It is observed that ZnO thin film is not sensitive to LPG (liquefied petroleum gas) at room temperature. On the other hand ZnO/PANI composite thin film shows good response and recovery behaviors at room temperature.

Birajadar, Ravikiran; Desale, Dipalee; Shaikh, Shaheed; Mahajan, Sandip; Upadhye, Deepak; Ghule, Anil; Sharma, Ramphal

2014-04-01

379

Estimation of aerosol water and chemical composition from AERONET at Cabauw, the Netherlands  

NASA Astrophysics Data System (ADS)

Remote sensing of aerosols provides important information on the atmospheric aerosol abundance. However, due to the hygroscopic nature of aerosol particles observed aerosol optical properties are influenced by atmospheric humidity, and the measurements do not unambiguously characterize the aerosol dry mass and composition which complicates the comparison with aerosol models. In this study we derive aerosol water and chemical composition by a modeling approach that combines individual measurements of remotely sensed aerosol properties (e.g. optical thickness, single scattering albedo, refractive index and size distribution) from an AERONET (Aerosol Robotic Network) sun-photometer with radiosonde measurements of relative humidity. The model simulates water uptake by aerosols based on the chemical composition and size distribution. A minimization method is used to calculate aerosol composition and concentration, which are then compared to in situ measurements from the Intensive Measurement Campaign At the Cabauw Tower (IMPACT, May 2008, the Netherlands). Computed concentrations show reasonable agreement with surface observations and follow the day-to-day variability in observations. Total dry mass (33 ± 12 ?g m-3) and black carbon concentrations (0.7 ± 0.3 ?g m-3) are generally accurately computed. The uncertainty in the AERONET (real) refractive index (0.025-0.05) introduces larger uncertainty in the modeled aerosol composition (e.g. sulfates, ammonium nitrate or organic matter) and leads to an uncertainty of 0.1-0.25 in aerosol water volume fraction. Water volume fraction is highly variable depending on composition, up to >0.5 at 70-80% and <0.1 at 40% relative humidity.

van Beelen, A. J.; Roelofs, G. J. H.; Hasekamp, O. P.; Henzing, J. S.; Röckmann, T.

2013-06-01

380

Chemical compositions of glomerular and tubular basement membranes of human kidney.  

PubMed

Glomerular basement membranes (GBM) and tubular basement membranes (TBM) were prepared from human kidney and their chemical compositions were studied. Electron microscopic figures showed no contamination of the cellular components components or collagen fibers, indicating a high degree of purity of the preparations. Low contents of phospholipid supported this indication. Amino acid compositions of the human GBM and TBM resembled that of the bovine GBM, containing hydroxyproline, hydroxylsine, half-cystine, methionine and a large amount of glycine as the characteristic amino acids. The human GBM and TBM had similar carbohydrate compositions consisting of glucose and galactose, as the major sugars, together with mannose, L-fucose, hexosamine and sialic acid. Glucosylgalactosylhydroxylysine and a small amount of galactosylhydroxylysine were detected in alkaline hydrolyzates of both membranes. The human GBM and TBM separated into more than ten subunits having molecular weights ranging from 2.5 times 10-4 to more than 2.5 times 10-5 on polyacrylamide gel electrophoresis in the presence of sodium laurylsulfate and 2-mercaptoethanol. The electrophoretograms of both membranes resembled that of the bovine GBM. These observations indicate that the human TBM has a similar chemical structure to those of the human GBM and the bovine GBM. PMID:1145613

Sato, T; Munakata, H; Yoshinaga, K; Yosizawa, Z

1975-04-01

381

On the heavy chemical composition of the ultra-high energy cosmic rays  

NASA Astrophysics Data System (ADS)

The Pierre Auger Observatory's (PAO) shower profile measurements can be used to constrain the chemical composition of the ultra-high energy cosmic ray (UHECR) spectrum. In particular, the PAO's measurements of the average depth of shower maximum and the fluctuations of the depth of shower maximum indicate that the cosmic ray spectrum is dominated by a fairly narrow distribution (in charge) of heavy or intermediate mass nuclei at the highest measured energies (E?1019eV), and contains mostly lighter nuclei or protons at lower energies (E˜1018eV). In this article, we study the propagation of UHECR nuclei with the goal of using these measurements, along with those of the shape of the spectrum, to constrain the chemical composition of the particles accelerated by the sources of the UHECRs. We find that with modest intergalactic magnetic fields, 0.3 nG in strength with 1 Mpc coherent lengths, good fits to the combined PAO data can be found for the case in which the sources accelerate primarily intermediate mass nuclei (such as nitrogen or silicon). Without intergalactic magnetic fields, we do not find any composition scenarios that can accommodate the PAO data. For a spectrum dominated by heavy or intermediate mass nuclei, the Galactic (and intergalactic) magnetic fields are expected to erase any significant angular correlation between the sources and arrival directions of UHECRs.

Hooper, Dan; Taylor, Andrew M.

2010-04-01

382

Mapping the nebular condensates and the chemical composition of the terrestrial planets  

NASA Astrophysics Data System (ADS)

We demonstrate that the condensation theory of planet formation yields solids of suitable compositions in the solar nebula that accrete to form the terrestrial planetary bodies. The mineral chemistry of the condensed objects provides definite criteria to establish the pressure and temperature of their formation. The solids condensing at a high nebular pressure of 0.01 to 0.001 bar and temperature of ?1530 K had the best chemical composition and density to form Mercury (64 wt% iron and 36 wt% oxides, density ?5.32 g cm). Solids that condensed around a pressure of 0.0001 bar or less and a temperature of ?700 K formed Earth and Venus (31 wt% iron, Ni and S and 69 wt% oxides, density ?4 g cm), and Mars (33.6 wt% Fe and S and 66.4 wt% oxides, density ?3.7 g cm). Iron sulfide provided S (3 wt%) for the core. Hydrous minerals forming in the lower temperature region provided water to the mantle. These results are highly significant because we have used only the chemical composition of the solar nebula, thermochemistry and astrophysical data on densities of the planets.

Saxena, Surendra K.; Hrubiak, Rostislav

2014-05-01

383

Estimation of aerosol water and chemical composition from POLDER/PARASOL satellite retrievals of aerosol properties.  

NASA Astrophysics Data System (ADS)

Remote sensing of aerosols provides important information on the atmospheric aerosol abundance. Due to the hygroscopic nature of aerosol particles, their optical properties reflect not only the dry aerosol properties but are also influenced by atmospheric humidity. Remotely sensed aerosol optical properties are used to validate aerosol-climate models, but a more consistent validation requires knowledge of the actual aerosol dry chemical composition. We present results from a model that estimates the dry aerosol chemical composition and aerosol water, using remotely sensed aerosol properties from POLDER/PARASOL (e.g. optical thickness, single scattering albedo, refractive index and size distribution) and ECMWF relative humidity as input. The model applies a minimization technique to derive column-integrated quantities of sulfate, ammonium nitrate, sea salt, organic matter, black carbon and dust, for the aerosol fine and coarse modes. First, we compare POLDER data with data from AERONET to assess the accuracy and consistency of the input data, and discuss the influence of uncertainties in optical parameters (especially the refractive index) on the model results. Then, the model is applied to POLDER measurements at several near-oceanic sites. The results are used to investigate the monthly and seasonal variability of aerosol abundance and composition at these sites.

van Beelen, Arjan; Roelofs, Geert-Jan; Hasekamp, Otto; Röckmann, Thomas

2014-05-01

384

Properties of thermo-chemically surface treated carbon fibers and of their epoxy and vinyl ester composites  

SciTech Connect

High strength carbon fibers were surface treated by a continuous gas phase thermo-chemical surface treatment. The surface and the mechanical properties of the fibers were investigated before and after treatment and compared to the properties obtained with a conventional industrial electro-chemical surface treatment. An increase of the oxygen atomic content from 3 % to 20 % with a preferential generation of carboxylic acid functionalities and hydroxyl groups was highlighted after the thermo-chemical surface treatment, compared to an oxygen atomic content of 7 % and a wide variety of oxygen moieties with the electro-chemical surface treatment. The tensile strength of the fibers increased slightly after the thermo-chemical surface treatment and remained the same after the electro-chemical surface treatment. Short beam shear and 90 flexural tests of composites revealed that the improvement of interfacial adhesion with a vinyl ester matrix was limited, revealing that oxidation of the carbon fiber surface alone cannot tremendously improve the mechanical properties of carbon fiber-vinyl ester composites. Atomic force microscopy showed that the creation of roughness with both surface treatments at a nanometric scale. Although the surface is slightly rougher after the electro-chemical surface treatment and is expected to lead to higher adhesion due to mechanical interlocking between the fiber surface and the matrix, the effect of covalent bonding coming from the high concentration of chemical groups on the surface results in higher adhesion strength, as obtained with the thermo-chemical surface treatment.

Vautard, Frederic [ORNL; Ozcan, Soydan [ORNL; Meyer III, Harry M [ORNL

2012-01-01

385

Chemical Analyses  

NASA Technical Reports Server (NTRS)

As a preliminary study on the effects of chemical aging of polymer materials MERL and TRI have examined two polymeric materials that are typically used for offshore umbilical applications. These two materials were Tefzel, a copolymer of ethylene and tetrafluoroethylene, and Coflon, polyvinylidene fluoride. The Coflon specimens were cut from pipe sections and exposed to H2S at various temperatures and pressures. One of these specimens was tested for methane permeation, and another for H2S permeation. The Tefzel specimens were cut from .05 mm sheet stock material and were exposed to methanol at elevated temperature and pressure. One of these specimens was exposed to methanol permeation for 2 days at 100 C and 2500 psi. An additional specimen was exposed to liquid methanol for 3 days at 150 C and 15 Bar. Virgin specimens of each material were similarly prepared and tested.

Bulluck, J. W.; Rushing, R. A.

1994-01-01

386

Characterization of the chemical composition of polyisobutylene-based oil-soluble dispersants by fluorescence.  

PubMed

A novel methodology based on fluorescence quenching measurements is introduced to determine quantitatively the amine content of polyisobutylene succinimide (PIBSI) dispersants used as engine oil-additives. To this end, a series of five PIBSI dispersants were prepared by reacting 2 mol equiv of polyisobutylene succinic anhydride (PIBSA) with 1 mol equiv of hexamethylenediamine (HMDA), diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and pentaethylenehexamine to yield the corresponding b-PIBSI dispersants. After having demonstrated that the presence of hydrogen bonds between the polyamine linker and the succinimide carbonyls of the dispersants prevents the quantitative analysis of the (1)H NMR and FTIR spectra of the dispersants to determine their chemical composition, alternative procedures based on gel permeation chromatography (GPC) and fluorescence quenching were implemented to estimate the amine content of the b-PIBSI dispersants. Taking advantage of the doubling in size that occurs when 2 mol of PIBSA are reacted with 1 mol of HMDA, a combination of GPC and FTIR was employed to follow how the chemical composition and molecular weight distribution of the polymers produced evolved with the reaction of PIBSA and HMDA mixed at different molar ratios. These experiments provided the PIBSA-to-HMDA molar ratio yielding the largest b-PIBSI dispersants and this molar ratio was then selected to prepare the four other dispersants. Having prepared five b-PIBSI dispersants with well-defined secondary amine content, the fluorescence of the succinimide groups was found to decrease with increasing number of secondary amines present in the polyamine linker. This result suggests that fluorescence quenching provides a valid method to determine the chemical composition of b-PIBSI dispersants which is otherwise difficult to characterize by standard (1)H NMR and FTIR spectroscopies. PMID:24628080

Pirouz, Solmaz; Wang, Yulin; Chong, J Michael; Duhamel, Jean

2014-04-10

387

Chemical reactions with aerosols  

NASA Astrophysics Data System (ADS)

Chemical reactions of aerosol droplets with vapors are discussed. Examples are given in which liquid aerosols of 1-octadecene of narrow size distribution are converted to 1,2-dibromooctadecane with bromine vapor. It was shown that the chemical reaction in the droplet controls the kinetics of this process. The application of chemical reactions with aerosols to the formation of pure, uniform spherical particles of metal oxides is also described. Droplets of metal alkoxides rapidly react with water vapor to yield well-defined powders. The technique was used to prepare titanium dioxide, aluminum oxide, and particles consisting of both metal oxides. This procedure allows generation of powders of predetermined size and composition.

Matijevi?, Egon

388

Composition and microstructure of chemically vapor-deposited boron nitride, aluminum nitride, and boron nitride + aluminum nitride composites  

SciTech Connect

The composition and microstructure of dispersed-phase ceramic composites containing BN and AlN as well as BN and AlN single-phase ceramics prepared by chemical vapor deposition have been characterized using X-ray diffraction, scanning electron microscopy, electron microprobe, and transmission electron microscopy techniques. Under certain processing conditions, the codeposited coating microstructure consists of small single-crystal AlN fibers (whiskers) surrounded by a turbostratic BN matrix. Other processing conditions resulted in single-phase films of AlN with a fibrous structure. The compositions of the codeposits range from 2 to 50 mol% BN, 50 to 80 mol% AlN with 7% to 25% oxygen impurity as determined by electron microprobe analysis.

Hanigofsky, J.A.; More, K.L.; Lackey, W.J.; Lee, W.Y.; Freeman, G.B. (Georgia Technology Research Inst., School of Materials Engineering, and School of Chemical Engineering, Georgia Inst. of Technology, Atlanta, GA (US))

1991-02-01

389

Chemical composition of late-type supergiants. IV. Homogeneous abundances and galactic metallicity trends  

SciTech Connect

In a recent series of papers by Luck and by Luck and Bond on the chemical composition of G and K lb supergiants, (Fe/H) ratios were determined from high-dispersion spectroscopic data for 54 stars. The main results were: (1) that supergiants in the solar neighborhood have about twice the iron content of the Sun (<(Fe/H)> = +0.3); and (2) that supergiants between 7.7 and 10.2 kpc from the galactic center show a steep radial metallicity gradient, d(Fe/H)/dR = -0.24 kpc/sup -1/.

Luck, R.E.

1982-05-01

390

An X-Ray Tomography Based Modeling Solution For Chemical Vapor Infiltration Of Ceramic Matrix Composites  

NASA Astrophysics Data System (ADS)

A numerical tool for the simulation of Chemical Vapor Infiltration of carbon/carbon composites is introduced. The structure of the fibrous medium can be studied by high resolution X-Ray Computed Micro Tomography. Gas transport in various regimes is simulated by a random walk technique whilst the morphological evolution of the fluid/solid interface is handled by a Marching Cube technique. The program can be used to evaluate effective diffusivity and first order reaction rate. The numerical tool is validated by comparing computed effective properties of a straight slit pore with reactive walls to their analytical expression. Simulation of CVI processing of a real complex media is then presented.

Ros, William; Vignoles, Gérard L.; Germain, Christian

2010-05-01

391

Morphological and photoluminescence study of chemically synthesized Al2O3 polythiophene composite  

NASA Astrophysics Data System (ADS)

Undoped and Al2O3 doped Polythiophene were synthesized by chemical route method. All the samples were characterized by fourier transform infra-red spectroscopy. Scanning electron microscopy shows the formation of spherical like particles for Al2O3 polythiophene composite and its size decreases continuously as Al2O3 doping percentage increases. Photoluminescence spectra were recorded at excitation wavelength 325 nm. All the samples have mainly two visible peaks at 462 and 490 nm respectively. The PL of present sample may have several optoelectronic applications like organic light emitting diodes (OLEDs), and photovoltaic cell etc.

Tripathi, Akhilesh; Bahadur, Indra; Shukla, R. K.

2014-04-01

392

LOAD TRANSFER AND MECHANICAL PROPERTIES OF CHEMICALLY DERIVED SINGLE LAYER GRAPHENE REINFORCEMENTS IN POLYMER COMPOSITES  

PubMed Central

We report load transfer and mechanical properties of chemically derived single layer graphene (SLG) as reinforcements in poly (dimethyl) siloxane (PDMS) composites. Mixing single layer graphene in polymers resulted in the marked decrease of the G’ or 2D band intensity due to doping and functionalization. A Raman G mode shift of 11.2 cm?1/% strain in compression and 4.2 cm?1/% strain in tension is reported. An increase in elastic modulus of PDMS by ~42%, toughness by ~39%, damping capability by ~673%, and strain energy density of ~43% by the addition of 1 wt. % SLG in PDMS is reported.

Xu, Peng; Loomis, James; Panchapakesan, Balaji

2013-01-01

393

Chemical Composition of Subway Particles in Seoul, Korea, Determined Using Quantitative Single Particle Analysis  

Microsoft Academic Search

\\u000a A novel single particle analytical technique, called low-Z particle electron probe X-ray microanalysis, was applied to characterize seasonal indoor aerosol samples collected at a subway\\u000a station in Seoul, Korea. Four major types of particles, based on their chemical compositions, are significantly encountered:\\u000a Fe-containing; soil-derived; carbonaceous; and secondary nitrate and\\/or sulfate particles. Fe-containing particles are present\\u000a in the greatest amounts, with

Hae-Jin Jung; Sunni Kang; Hye Kyeong Kim; Chul-Un Ro

394

Chemical composition and antioxidant activity of the essential oil of Juniperus phoenicea L. berries.  

PubMed

This study is designed to examine the chemical composition and antioxidant activity of the essential oil of Juniperus phoenicea L. ripe and unripe berries. GC and GC/MS analyses resulted in the detection of 42 components representing approximately 96.50-99.57% of the oils. Major components of the oils were ?-pinene (58.61-77.39%), camphene (0.67-9.31%), ?-3-carene (0-10.01%) and trans-verbenol (0-5.24%). Antioxidant activities were determined by two different test systems, DPPH and ABTS radical scavenging activities. In both systems ripe berries exhibited better activity potential than the unripe ones. PMID:21838538

Medini, Hanène; Elaissi, Ameur; Larbi Khouja, Med; Piras, Alessandra; Porcedda, Silvia; Falconieri, Danilo; Marongiu, Bruno; Chemli, Rachid

2011-10-01

395

Chemical composition and antibacterial activity of the essential oil from Mentha requienii Bentham.  

PubMed

The chemical composition of essential oil obtained by hydrodistillation of the fresh aerial parts of Mentha requienii Bentham (Lamiaceae) collected on the Gennargentu Mountains (Sardinia, Italy) has been investigated by gas chromatography and gas chromatography-mass spectrometry. The main constituents that resulted were pulegone (78%), menthone (0.5%), isomenthone (18%), isopulegone (1.3%) and limonene (1.76%). In vitro antifungal activity is evaluated in order to identify new means that could be helpful in the prevention of contamination in indoor environments. PMID:22385272

Chessa, Mario; Sias, Angela; Piana, Andrea; Mangano, Giuseppe Salvatore; Petretto, Giacomo Luigi; Masia, Maria Dolores; Tirillini, Bruno; Pintore, Giorgio

2013-01-01

396

Collision as a way of forming bimetallic nanoclusters of various structures and chemical compositions.  

PubMed

In the present work, a new way to obtain bimetallic nanoclusters of different structures and chemical compositions is proposed, which is based on computer simulations. Collision processes between two metal clusters of different natures are simulated through molecular-dynamics simulations using many-body potentials. Diverse diffusion mechanisms and structures can be observed, depending on the metals combined and the initial kinetic energies. The nanostructures we have found are core-shell (Pt-Au), alloyed (Pd-Au), and three-shell onionlike (Cu-Ag). PMID:16292912

Mariscal, Marcelo M; Dassie, Sergio A; Leiva, Ezequiel P M

2005-11-01

397

Collision as a way of forming bimetallic nanoclusters of various structures and chemical compositions  

NASA Astrophysics Data System (ADS)

In the present work, a new way to obtain bimetallic nanoclusters of different structures and chemical compositions is proposed, which is based on computer simulations. Collision processes between two metal clusters of different natures are simulated through molecular-dynamics simulations using many-body potentials. Diverse diffusion mechanisms and structures can be observed, depending on the metals combined and the initial kinetic energies. The nanostructures we have found are core-shell (Pt-Au), alloyed (Pd-Au), and three-shell onionlike (Cu-Ag).

Mariscal, Marcelo M.; Dassie, Sergio A.; Leiva, Ezequiel P. M.

2005-11-01

398

Chemical composition and antibacterial activity of essential oil of Heracleum rechingeri Manden from Iran.  

PubMed

The chemical composition of the essential oil from Heracleum rechingeri was analysed using GC-MS. Twenty-seven compounds, accounting for 94.62% of the extracted essential oil, were identified. The main oil compounds were octyl acetate (29.49%), elemicine (23.06%), (E)-caryophyllene (9.26%), caryophyllene oxide (6.42%), terpinolene (6.12%) and (Z)-3-octenyl acetate (4.72%). The antimicrobial activity of the essential oil was tested against three different bacteria by disc diffusion method and showed maximum inhibitory activity against Gram-positive bacteria, especially Bacillus subtilis. PMID:20552523

Habibi, Zohreh; Eshaghi, Rasool; Mohammadi, Mehdi; Yousefi, Maryam

2010-07-01

399

Influence of electropolishing and anodic oxidation on morphology, chemical composition and corrosion resistance of niobium.  

PubMed

The work presents results of the studies performed on electropolishing of pure niobium in a bath that contained: sulphuric acid, hydrofluoric acid, ethylene glycol and acetanilide. After the electropolishing, the specimens were subjected to anodic passivation in a 1moldm(-3) phosphoric acid solution at various voltages. The surface morphology, thickness, roughness and chemical composition of the resulting oxide layers were analysed. Thusly prepared niobium samples were additionally investigated in terms of their corrosion resistance in Ringer's solution. The electropolished niobium surface was determined to be smooth and lustrous. The anodisation led to the growth of barrier-like oxide layers, which were enriched in phosphorus species. PMID:25063150

Sowa, Maciej; Gre?, Katarzyna; Kukharenko, Andrey I; Korotin, Danila M; Michalska, Joanna; Szyk-Warszy?ska, Lilianna; Mosia?ek, Micha?; Zak, Jerzy; Pamu?a, El?bieta; Kurmaev, Ernst Z; Cholakh, Seif O; Simka, Wojciech

2014-09-01

400

Measurement of gas transport through fiber preforms and densified composites for chemical vapor infiltration  

SciTech Connect

Gas transport via pressure-driven permeation or via concentration-driven diffusion is a key step in the chemical vapor infiltration (CVI) process. This paper describes methods for the measurement of these properties for CVI preforms and partially infiltrated composites. Results are presented for Nicalon-fiber cloth layup preforms and composites, Nextel-fiber braid preforms and composites, and a Nicalon-fiber three-dimensional (3-D) weave composite. The permeability of Nicalon cloth layup preforms is strongly dependent on the packing density over the range of 29--40 vol% but is only weakly dependent on the orientation of the alternating cloth layers. The permeability of Nextel braid preforms is dependent on the thread count and the weight for cloths with similar construction and packing density. The gas permeability of the finer wave (6.3 tows/cm (16 tows/in.)) is approximately one-half that of the coarser weave (3.5 tows/cm (9 tows/in.)). Results are reported for a small number of infiltrated composites with Nextel fiber reinforcement. Attempts to mount a Nicalon-fiber 3-D weave preform specimen have been unsuccessful. Results for a small number of composite specimens with 3-D weave reinforcement are reported.

Starr, T.L.; Hablutzel, N. [Georgia Inst. of Tech., Atlanta, GA (United States). School of Materials Science and Engineering

1998-05-01

401

Influence of origin and extraction method on argan oil physico-chemical characteristics and composition.  

PubMed

Twenty one samples of argan oil of different geographical origin (Tidzi, Tamanar, Benaiznassen, Ait mzal, Ait Baha, Ighrem, Aoulouz) and/or prepared following a different process (traditional, mechanical, or industrial) were collected and their physico-chemical properties analyzed. Sample acidity was found between 0.14 and 1.40%, unsaponifiable matter between 0.34 and 0.79%, saponification value between 180.0 and 199.6, highest peroxide index was 5.72 meq/kg, refractive index (20 degrees C) between 1.4644 and 1.4705, and UV absorption at 270 nm between 0.228 and 0.605. This study, carried out on randomly selected samples, clearly demonstrates that press extraction does not alter either the chemical composition of argan oil or its physico-chemical characteristics. It also demonstrates that press extraction respects the critical factors reported for traditionally prepared oils and necessary to obtain a beneficial effect on human health (a specific fatty acid balance and high tocopherol and sterol levels). In addition, this study should be useful for the establishment of a national quality standard. PMID:15769139

Hilali, Miloudi; Charrouf, Zoubida; Soulhi, Abd El Aziz; Hachimi, Larbi; Guillaume, Dominique

2005-03-23

402

Influence of Aerosol Acidity on the Chemical Composition of Secondary Organic Aerosol from ?-caryophyllene  

NASA Astrophysics Data System (ADS)

The secondary organic aerosol (SOA) yield of ?-caryophyllene photooxidation is enhanced by aerosol acidity. In the present study, the influence of aerosol acidity on the chemical composition of ?-caryophyllene SOA is investigated using ultra performance liquid chromatography/electrospray ionization-time-of-flight mass spectrometry (UPLC/ESI- TOFMS). A number of first- , second- and higher-generation gas-phase products having carbonyl and carboxylic acid functional groups are detected in the particle phase. Particle-phase reaction products formed via hydration and organosulfate formation processes are also detected. Increased acidity leads to different effects on the abundance of individual products; significantly, abundances of organosulfates are correlated with aerosol acidity. The increase of certain particle-phase reaction products with increased acidity provides chemical evidence to support the acid-enhanced SOA yields. Based on the agreement between the chromatographic retention times and accurate mass measurements of chamber and field samples, three ?-caryophyllene products (i.e., ?-nocaryophyllon aldehyde, ?-hydroxynocaryophyllon aldehyde, and ?-dihydroxynocaryophyllon aldehyde) are suggested as chemical tracers for ?-caryophyllene SOA. These compounds are detected in both day and night ambient samples collected in downtown Atlanta, GA and rural Yorkville, GA during the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS).

Chan, M.; Surratt, J. D.; Chan, A. W.; Schlling, K.; Offenberg, J. H.; Lewandowski, M.; Edney, E.; Kleindienst, T. E.; Jaoui, M.; Edgerton, E. S.; Tanner, R. L.; Shaw, S. L.; Zheng, M.; Knipping, E. M.; Seinfeld, J.

2011-12-01

403

Influence of aerosol acidity on the chemical composition of secondary organic aerosol from ?-caryophyllene  

NASA Astrophysics Data System (ADS)

The secondary organic aerosol (SOA) yield of ?-caryophyllene photooxidation is enhanced by aerosol acidity. In the present study, the influence of aerosol acidity on the chemical composition of ?-caryophyllene SOA is investigated using ultra performance liquid chromatography/electrospray ionization-time-of-flight mass spectrometry (UPLC/ESI-TOFMS). A number of first-, second- and higher-generation gas-phase products having carbonyl and carboxylic acid functional groups are detected in the particle phase. Particle-phase reaction products formed via hydration and organosulfate formation processes are also detected. Increased acidity leads to different effects on the abundance of individual products; significantly, abundances of organosulfates are correlated with aerosol acidity. To our knowledge, this is the first detection of organosulfates and nitrated organosulfates derived from a sesquiterpene. The increase of certain particle-phase reaction products with increased acidity provides chemical evidence to support the acid-enhanced SOA yields. Based on the agreement between the chromatographic retention times and accurate mass measurements of chamber and field samples, three ?-caryophyllene products (i.e., ?-nocaryophyllon aldehyde, ?-hydroxynocaryophyllon aldehyde, and ?-dihydroxynocaryophyllon aldehyde) are suggested as chemical tracers for ?-caryophyllene SOA. These compounds are detected in both day and night ambient samples collected in downtown Atlanta, GA and rural Yorkville, GA during the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS).

Chan, M. N.; Surratt, J. D.; Chan, A. W. H.; Schilling, K.; Offenberg, J. H.; Lewandowski, M.; Edney, E. O.; Kleindienst, T. E.; Jaoui, M.; Edgerton, E. S.; Tanner, R. L.; Shaw, S. L.; Zheng, M.; Knipping, E. M.; Seinfeld, J. H.

2011-02-01

404

Influence of aerosol acidity on the chemical composition of Secondary Organic Aerosol from ?-caryophyllene  

NASA Astrophysics Data System (ADS)

The secondary organic aerosol (SOA) yield of ?-caryophyllene photooxidation is enhanced by aerosol acidity. In the present study, the influence of aerosol acidity on the chemical composition of ?-caryophyllene SOA is investigated using ultra performance liquid chromatography/electrospray ionization-time-of-flight mass spectrometry (UPLC/ESI-TOFMS). A number of first-, second- and higher-generation gas-phase products having carbonyl and carboxylic acid functional groups are detected in the particle phase. Particle-phase reaction products formed via hydration and organosulfate formation processes are also detected. Increase of acidity leads to different effects on the abundance of individual products; significantly, abundances of organosulfates are correlated with aerosol acidity. To our knowledge, this is the first detection of organosulfates and nitrated organosulfates derived from a sesquiterpene. The increase of certain particle-phase reaction products with increased acidity provides chemical evidence to support the acid-enhanced SOA yields. Based on the agreement between the chromatographic retention times and accurate mass measurements of chamber and field samples, three ?-caryophyllene products (i.e., ?-nocaryophyllon aldehyde, ?-hydroxynocaryophyllon aldehyde, and ?-dihydroxynocaryophyllon aldehyde) are identified as chemical tracers for ?-caryophyllene SOA. These compounds are detected in both day and night ambient samples collected in downtown Atlanta, GA and rural Yorkville, GA during the 2008 August Mini-Intensive Gas and Aerosol Study (AMIGAS).

Chan, M. N.; Surratt, J. D.; Chan, A. W. H.; Schilling, K.; Offenberg, J. H.; Lewandowski, M.; Edney, E. O.; Kleindienst, T. E.; Jaoui, M.; Edgerton, E. S.; Tanner, R. L.; Shaw, S. L.; Zheng, M.; Knipping, E. M.; Seinfeld, J. H.

2010-11-01

405

Chemical composition and biological activity of ripe pumpkin fruits (Cucurbita pepo L.) cultivated in Egyptian habitats.  

PubMed

The chemical composition and biological activity of three parts (rind, flesh and seeds) of pumpkin fruits (Cucurbita pepo L.) cultivated in Egypt were studied. Chemical analysis of fibre, protein, ?-carotene, carbohydrates, minerals and fatty acids present in the rind, flesh, seeds and defatted seeds meal was conducted. Chemical, GC-MS and biological assays of organic extracts of the main fruit parts, rind and flesh established their unique constituents. Chromatographic purification of the extracts afforded triglyceride fatty acid mixture (1), tetrahydro-thiophene (2), linoleic acid (3), calotropoleanly ester (4), cholesterol (5) and 13(18)-oleanen-3-ol (6). GC-MS analysis of the extract's unpolar fraction revealed the existence of dodecane and tetradecane. Structures of the isolated compounds (1-6) were confirmed by NMR and EI-MS spectrometry. Antimicrobial, antiviral and antitumour activities of the fruit parts were discussed. The promising combined extract of rind and flesh was biologically studied for microbial and cytotoxic activities in comparison with the whole isolated components. PMID:20603772

Badr, Sherif E A; Shaaban, Mohamed; Elkholy, Yehya M; Helal, Maher H; Hamza, Akila S; Masoud, Mohamed S; El Safty, Mounir M

2011-09-01

406

Biosorption of heavy metal ions from aqueous solutions by short hemp fibers: Effect of chemical composition.  

PubMed

Sorption potential of waste short hemp fibers for Pb(2+), Cd(2+) and Zn(2+) ions from aqueous media was explored. In order to assess the influence of hemp fiber chemical composition on their heavy metals sorption potential, lignin and hemicelluloses were removed selectively by chemical modification. The degree of fiber swelling and water retention value were determined in order to evaluate the change in accessibility of the cell wall components to aqueous solutions due to the fiber modification. The effects of initial ion concentration, contact time and cosorption were studied in batch sorption experiments. The obtained results show that when the content of either lignin or hemicelluloses is progressively reduced by chemical treatment, the sorption properties of hemp fibers are improved. Short hemp fibers are capable of sorbing metal ions (Pb(2+), Cd(2+) and Zn(2+)) from single as well as from ternary metal ion solutions. The maximum total uptake capacities for Pb(2+), Cd(2+) and Zn(2+) ions from single solutions are the same, i.e. 0.078mmol/g, and from ternary mixture 0.074, 0.035 and 0.035mmol/g, respectively. PMID:18778893

Pejic, Biljana; Vukcevic, Marija; Kostic, Mirjana; Skundric, Petar

2009-05-15

407

Electroluminescence from Au/Si oxynitride film/Si structures with the films having different chemical compositions  

NASA Astrophysics Data System (ADS)

Si oxynitride films (with thicknesses of about 40 - 80 Å) with different chemical compositions were deposited on Si wafers by three kinds of method: electron cyclotron resonance (ECR) chemical vapour deposition, magnetron sputtering, and direct nitration of Si wafers in an ECR plasma. The chemical composition of Si oxynitride films was examined by x-ray photoelectron spectroscopy. Electroluminescence (EL) from the semitransparent Au/Si oxynitride film/Si structures, and the effects of chemical composition of the films on EL have been studied. The dependence of EL on thermal annealing has also been reported. Experimental results show that the dominant EL peak position varies from 640 to 700 nm, but the shoulders at about 520 and 820 nm have no apparent shift when the Si content in the Si oxynitride films increases.

Li, A. P.; Zhang, L. D.; Qiao, Y. P.; Qin, G. G.; Ma, Z. C.; Zong, W. H.; Wang, Xin; Hu, X. W.

1997-06-01

408

Thermodynamic Modeling of the Chemical Composition of Calcine at the Idaho Nuclear Technology and Engineering Center  

SciTech Connect

To send calcine produced at Idaho National Engineering and Environmental Laboratory to the Yucca Mountain Project for disposal, characterization information will be required. To sample calcine from its existing storage location would require extensive personnel exposure. Sufficient analyses of the chemical composition of the calcine would be extremely difficult and very expensive. In support of characterization development, the chemical composition of calcine from Bin 3 of Calcine Solid Storage Facility II was thermodynamic modeled. This calcine was produced in the Waste Calcination Facility during its second processing campaign, operating with indirect heating at 400 C and 0.744 bar (0.734 atm) during processing of aluminum high-level liquid waste (first cycle extraction raffinate from reprocessing aluminum-clad fuels) from tanks WM-180 and -182 from December 27, 1966 through August 26, 1967. The current modeling effort documents the input compositional data (liquid feed and calciner off-gas) for Batches 300 - 620 and a methodology for estimating the calcine chemical composition. The results, along with assumptions and limitations of the thermodynamic calculations, will serve as a basis for benchmarking subsequent calculations. This will be done by comparing the predictions against extensive analytical results that are currently being obtained on representative samples of the modeled calcine. A commercial free-energy minimization program and database, HSC 5.1, was used to perform the thermodynamic calculations. Currently available experimental data and process information on the calcine were used to make judgments about specific phases and compounds to include and eliminate in the thermodynamic calculations. Some off-gas species were eliminated based on kinetics restrictions evidenced by experimental data and other estimates, and some calcine components and off-gas compounds were eliminated as improbable species (unreliable thermodynamic data). The current Yucca Mountain Project level of concern is 0.1 wt % of individual cations in the waste package. Chemical composition of the individual calcine components was calculated down to 0.02 mol % and 0.09 wt % of metal components of the calcine. The results reproduce closely existing experimental information on calcine chemical and phase composition. This paper discusses specific conditions accepted for the final calculations. The major calcine components, exceeding 0.15 mol % and 0.65 wt %, are: amorphous Al2O3 (85.30 mol %, 81.20 wt %); amorphous NaNO3 (8.23 mol %, 6.53 wt %); dolomite – CaMg 0.9235 (CO3)1.9235 (1.66 mol %, 2.75 wt %); amorphous HgO (0.99 mol %, 2.00 wt %); CaSO4 (0.64 mol %, 0.82 wt %); amorphous KNO3 (0.63 mol %, 0.59 wt %); amorphous Al4B2O9 (0.54 mol %, 1.37 wt %); and amorphous Al18B4O33 (0.16 mol %, 1.57 wt %). Na is present 99.8 % as NaNO3, 99.9 % of K is present as KNO3, and 53 % NOx is NO2(g), showing that the kinetics limiting effects have been empirically accounted for in the modeling. Approximately 87 % of the mercury is in calcine.

C. M. Frazee; J. D. Christian

2004-02-01

409

A composite numerical model for assessing subsurface transport of oily wastes and chemical constituents  

NASA Astrophysics Data System (ADS)

Subsurface fate and transport models are utilized to predict concentrations of chemicals leaching from wastes into downgradient receptor wells. The contaminant concentrations in groundwater provide a measure of the risk to human health and the environment. The level of potential risk is currently used by the U.S. Environmental Protection Agency to determine whether management of the wastes should conform to hazardous waste management standards. It is important that the transport and fate of contaminants is simulated realistically. Most models in common use are inappropriate for simulating the migration of wastes containing significant fractions of nonaqueous-phase liquids (NAPLs). The migration of NAPL and its dissolved constituents may not be reliably predicted using conventional aqueous-phase transport simulations. To overcome this deficiency, an efficient and robust regulatory assessment model incorporating multiphase flow and transport in the unsaturated and saturated zones of the subsurface environment has been developed. The proposed composite model takes into account all of the major transport processes including infiltration and ambient flow of NAPL, entrapment of residual NAPL, adsorption, volatilization, degradation, dissolution of chemical constituents, and transport by advection and hydrodynamic dispersion. Conceptually, the subsurface is treated as a composite unsaturated zone-saturated zone system. The composite simulator consists of three major interconnected computational modules representing the following components of the migration pathway: (1) vertical multiphase flow and transport in the unsaturated zone; (2) areal movement of the free-product lens in the saturated zone with vertical equilibrium; and (3) three-dimensional aqueous-phase transport of dissolved chemicals in ambient groundwater. Such a composite model configuration promotes computational efficiency and robustness (desirable for regulatory assessment applications). Two examples are presented to demonstrate the model verification and a site application. Simulation results obtained using the composite modeling approach are compared with a rigorous numerical solution and field observations of crude oil saturations and plume concentrations of total dissolved organic carbon at a spill site in Minnesota, U.S.A. These comparisons demonstrate the ability of the present model to provide realistic depiction of field-scale situations.

Panday, S.; Wu, Y. S.; Huyakorn, P. S.; Wade, S. C.; Saleem, Z. A.

1997-02-01

410

Chemical diversity of Ziziphora clinopodioides: composition of the essential oil of Z. clinopodioides from Tajikistan.  

PubMed

The chemical composition of the essential oils of Ziziphora clinopodioides Lam. from the aerial flowering parts, collected during two different years, were obtained by hydrodistillation and analyzed by gas chromatography - mass spectrometry. Forty-five components representing 100% and 94.7% of the total oil were identified. The main constituents of the essential oils were pulegone (72.8 and 35.0%), neomenthol (6.5 and 23.1%), menthone (6.2 and 13.3%), p-menth-3-en-8-ol (1.7 and 3.5%), piperitenone (2.6 and 1.1%) and piperitone (0.7 and 1.2%). A cluster analysis was carried out on the essential oil compositions of Z. clinopodioides. PMID:21615034

Sharopov, Farukh S; Setzer, William N

2011-05-01

411

Chemical composition, quality and histochemical characteristics of individual dromedary camel (Camelus dromedarius) muscles.  

PubMed

This study characterized the chemical composition, quality and histological traits of six muscles from 10 dromedary carcasses. There were significant differences in moisture, fat, protein, mineral, saturated and unsaturated fatty acid contents between muscles. The longissimus thoracis (LT) had the highest cooking loss (33.5%) and triceps brachii (TB) the lowest (29.2%). The shear force value of semitendinosus (ST), semimembranosus (SM) and biceps femoris (BF) were significantly higher than infraspinatus (IS), TB and LT. The LT had significantly higher values for L*, a*, b* than ST. The SM had the lowest MFI (65.3), while IS had the highest value (75.8). The ST significantly had the highest and lowest proportions of Type I and Type IIA muscle fibers, respectively than other muscles. This study indicated that composition, quality, and histochemical parameters varied among camel muscles and the knowledge of this variation allows for better marketing and processing of camel meat. PMID:23273465

Kadim, I T; Al-Karousi, A; Mahgoub, O; Al-Marzooqi, W; Khalaf, S K; Al-Maqbali, R S; Al-Sinani, S S H; Raiymbek, G

2013-03-01

412

Photothermal method for in situ microanalysis of the chemical composition of coal samples  

DOEpatents

Successive minute regions along a scan path on a coal sample are individually analyzed, at a series of different depths if desired, to determine chemical composition including the locations, sizes and distributions of different maceral inclusions. A sequence of infrared light pulses of progressively changing wavelengths is directed into each minute region and a probe light beam is directed along the sample surface adjacent the region. Infrared wavelengths at which strong absorption occurs in the region are identified by detecting the resulting deflections of the probe beam caused by thermally induced index of refraction changes in the air or other medium adjacent the region. The detected peak absorption wavelengths are correlated with known characteristic peak absorption wavelengths of specific coal constituents to identify the composition of each such minute region of the sample. The method enables rapid, convenient and non-destructive analyses of coal specimens to facilitate mining, processing and utilization of coals. 2 figures.

Amer, N.M.

1983-10-25

413

The Chemical Composition and Nitrogen Distribution of Chinese Yak (Maiwa) Milk  

PubMed Central

The paper surveyed the chemical composition and nitrogen distribution of Maiwa yak milk, and compared the results with reference composition of cow milk. Compared to cow milk, yak milk was richer in protein (especially whey protein), essential amino acids, fat, lactose and minerals (except phosphorus). The contents of some nutrients (total protein, lactose, essential amino acids and casein) were higher in the warm season than in the cold season. Higher ratios of total essential amino acids/total amino acids (TEAA/TAA) and total essential amino acids/total non essential amino acids (TEAA/TNEAA) were found in the yak milk from the warm season. However its annual average ratio of EAA/TAA and that of EAA/NEAA were similar to those of cow milk. Yak milk was rich in calcium and iron (p < 0.05), and thus may serve as a nutritional ingredient with a potential application in industrial processing.

Li, Haimei; Ma, Ying; Li, Qiming; Wang, Jiaqi; Cheng, Jinju; Xue, Jun; Shi, John

2011-01-01

414

Simple chemical solution coating and gas sensing properties of ?-Fe2O3/chrysotile fibrous composites  

NASA Astrophysics Data System (ADS)

?-Fe2O3/chrysotile fibrous composites were prepared by a simple chemical solution coating method for the gas sensitivity improvement of ?-Fe2O3. X-ray diffraction (XRD) and atomic force microscope (AFM) analyses indicate that corundum-type ?-Fe2O3 nanoparticles with a mean particle size ˜20 nm are dense and well-proportioned on the surface of chrysotile fibers due to the mechanism that positively charged Fe(OH)3 particles can be adsorbed onto the negatively charged chrysotile fibers in acidic liquids. The fabricated sensor devices were characterized for their electrical and gas sensing properties, it is found that the sensitivities of ?-Fe2O3/chrysotile fibrous composites to H2 and CH4 all increase by ˜35% than those of the single ?-Fe2O3 nanoparticles. Such simple coating treatment is an effective way in improving the continuities and gas sensing properties of nanogranular thick films.

Liu, Haifeng; Peng, Tongjiang; Ma, Guohua; Sun, Hongjuan; Hu, Hailong

2012-03-01

415

Chemical composition and binary mixture of human urinary stones using FT-Raman spectroscopy method.  

PubMed

In the present study the human urinary stones were observed in their different chemical compositions of calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, struvite (magnesium ammonium phosphate), uric acid, cystine, oxammite (ammonium oxalate monohydrate), natroxalate (sodium oxalate), glushinkite (magnesium oxalate dihydrate) and moolooite (copper oxalate) were analyzed using Fourier Transform-Raman (FT-Raman) spectroscopy. For the quantitative analysis, various human urinary stone samples are used for ratios calculation of binary mixtures compositions such as COM/COD, HAP/COD, HAP/COD, Uric acid/COM, uric acid/COD and uric acid/HAP. The calibration curve is used for further analysis of binary mixture of human urinary stones. For the binary mixture calculation the various intensities bands at 1462 cm(-1) (I(COM)), 1473 cm(-1) (I(COD)), 961 cm(-1) (I(HAP)) and 1282 cm(-1) (I(UA)) were used. PMID:23816485

Selvaraju, R; Raja, A; Thiruppathi, G

2013-10-01

416

Chemical composition and binary mixture of human urinary stones using FT-Raman spectroscopy method  

NASA Astrophysics Data System (ADS)

In the present study the human urinary stones were observed in their different chemical compositions of calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, struvite (magnesium ammonium phosphate), uric acid, cystine, oxammite (ammonium oxalate monohydrate), natroxalate (sodium oxalate), glushinkite (magnesium oxalate dihydrate) and moolooite (copper oxalate) were analyzed using Fourier Transform-Raman (FT-Raman) spectroscopy. For the quantitative analysis, various human urinary stone samples are used for ratios calculation of binary mixtures compositions such as COM/COD, HAP/COD, HAP/COD, Uric acid/COM, uric acid/COD and uric acid/HAP. The calibration curve is used for further analysis of binary mixture of human urinary stones. For the binary mixture calculation the various intensities bands at 1462 cm-1 (ICOM), 1473 cm-1 (ICOD), 961 cm-1 (IHAP) and 1282 cm-1 (IUA) were used.

Selvaraju, R.; Raja, A.; Thiruppathi, G.

2013-10-01

417

Chemical composition and biological properties of portuguese wild mushrooms: a comprehensive study.  

PubMed

The chemical composition and biological properties of Portuguese wild mushrooms ( Cantharellus cibarius, Hypholoma fasciculare, Lepista nuda, Lycoperdon molle, Lycoperdon perlatum, Ramaria botrytis, Tricholoma acerbum) were evaluated in order to assess these products as sources of nutrients and nutraceuticals. The analyzed mushrooms contain very useful phytochemicals such as phenolics, tocopherols, ascorbic acid, and carotenoids. All of the species proved to have antioxidant activity (measured by four different methods), being more significant for R. botrytis (EC 50 values < 1 mg/mL). Lycoperdon species were resistant to all of the tested microorganisms, and the other samples revealed antimicrobial activity selectively against Gram-positive bacteria, with very low minimal inhibitory concentration, in some cases, even lower than the standard. The combination of bioactive compounds and rich nutritional composition (high contents in protein and carbohydrates, low content in fat with the precious contribution of unsaturated fatty acids and the absence of trans fatty acids) in the mushroom makes it a very special food. PMID:18435539

Barros, Lillian; Venturini, Bruna A; Baptista, Paula; Estevinho, Letícia M; Ferreira, Isabel C F R

2008-05-28

418

Chemical composition and its origin in spring rainwater over Taihu Lake  

NASA Astrophysics Data System (ADS)

Chemical compositions of rainwater collected in three stations in Taihu Lake in Jiangsu Province, China between March and May 2003 were analyzed through numerical simulations and field observation data. In terms of average ion deposition rate in spring at the air/water interface, of all anions, that of SO{4/2-} was the largest followed by NO{3/-}, whereas among all cations, Ca2+ concentration and the rate was the largest, and then NH{4/+} was the next. The correlation of ion concentration indicated that the catchment of the lake has been artificially polluted considerably. Using backward trajectory analysis, the raining water in the stations in Taihu Lake was classified. In spring, marine-originated rain is the main contribution to this area, counting for 92.7% of the total precipitation, in which SO{4/2-}, NO{3/-} and NH{4/-} contributed 89.2%, 88.1%, and 88.3% respectively to the total spring-rain chemicals, whereas land-originated rains contributed in a small amount. However, the ion concentration in the land-originated rain was higher and acidic, causing considerable harm to local ecosystem. The analysis of backward trajectory analysis shows that three types of air masses influenced the chemical composition of the lake water, namely, air mass from NE direction, air mass from SW direction, and local air mass. Although the local air masses often produced small rainfall amount, but the nature of high ion concentration and high acidity impacted the local ecosystem rmmarkably. The ion concentration and rainfall from long-distance boreal air mass are clearly greater than those in austral air.

Wang, Xuemei; Yang, Longyuan; Qin, Boqiang; Ji, Lingling

2006-12-01

419

The chemical composition of nanoparticles formed from the oxidation of real plant emissions  

NASA Astrophysics Data System (ADS)

Organic vapors from biosphere emissions clearly participate in the formation of secondary organic aerosol (SOA). Thereby volatile organic compounds (VOCs) are transformed by photolytic reactions to low volatility organic compounds capable of condensing onto particles even in a size range where the strong curvature typically prevents vapor condensation by most other condensable vapors (Kelvin effect). However, the exact compounds responsible for nanoparticle formation and growth largely remain unknown. In this study we conducted chamber experiments under well-defined conditions to investigate chemical and physical properties of aerosol particles formed from oxidation products of real plant emissions. The chamber used comprises of a 10 m^3 Teflon FEP bag, operated at room temperature. Emissions from specific plants, e.g., a pine tree, can be added to the chamber and may produce aerosol particles after oxidation with ozone and/or OH. Gas chromatographs, trace gas analyzers, and aerosol sizing instruments provide a comprehensive set of instruments to analyze gas phase composition and aerosol size distribution. The chemical composition of nanoparticles at a pre-selected size is analyzed with the thermal desorption chemical ionization mass spectrometer (TDCIMS) (Smith & Rathbone, Int. J. Mass Spectrom. 274, 8 (2008)) providing positive and negative ion mass spectra with a time resolution of about 10 minutes. Here we present results from the emissions of ponderosa pine, the dominant tree species in the Rocky Mountains. These data are directly compared to measurements obtained by the TDCIMS during the BEACHON-SRM08 field campaign, which took place from 15 July - 15 August 2008 at the NCAR Manitou Forest Observatory near Woodland Park, CO. This comparison also gives insight into the ability of these chambers to simulate biogenic SOA formation.

Winkler, P. M.; Ortega, J.; Barsanti, K. C.; Friedli, H. R.; Smith, J. N.

2010-12-01

420

Recent laboratory and field observations of the chemical composition of atmospheric nanoparticles  

NASA Astrophysics Data System (ADS)

This presentation will focus on understanding the species and mechanisms that are responsible for the formation and growth of atmospheric nanoparticles. We report 10 - 40 nm diameter nanoparticle chemical composition measurements performed in two coastal sites (Mace Head, Ireland, and Lewes, Delaware USA) and two forested sites (Hyytiälä, Finland, and Manitou Forest, Colorado USA) with the recently-developed High Resolution Time-of-Flight Thermal Desorption Chemical Ionization Mass Spectrometer (HTOF-TDCIMS). These field measurements are supplemented by laboratory experiments of particle formation and growth performed at NCAR using a flow tube apparatus and a Teflon bag reaction chamber, and by thermodynamic modeling. Together, our field and laboratory observations point to crucial roles played in nanoparticle growth by two compounds: organic acids and organonitrates. The first, organic acids, are major contributors to the organic fraction in sub-20 nm diameter biogenic nanoparticles but appear to be less abundant in the organic fraction of larger particles, the latter of which are dominated by multifunctional carbonyl- and alcohol-containing compounds. The observed changes in chemical composition of the organic fraction as a function of particle size are supported by thermodynamic modeling results. The second, organonitrates, are commonly found in ambient nanoparticles as small as 10 nm in diameter. However unlike organic acids, organonitrates become increasingly more important in nanoparticle growth as particle size increases. Laboratory experiments suggest that organonitrates formed from the nitrate radical oxidation of biogenic organic compounds, a subset of total organonitrates, exhibit particularly low volatility and can thus partition into the smallest nanoparticles. This is confirmed by HTOF-TDCIMS measurements of 10 - 20 nm diameter particles, which show that particulate phase organonitrates peak in the morning, shortly following the period where organonitrates are believed to be formed by nitrate radical chemistry.

Smith, J. N.; Winkler, P.; Hildebrandt Ruiz, L.; Lawler, M. J.; Ortega, J.; Fry, J.; Barsanti, K. C.; McMurry, P. H.; Johnston, M. V.

2012-12-01

421

Microstructure and mechanical properties of three-dimensional carbon\\/silicon carbide composites fabricated by chemical vapor infiltration  

Microsoft Academic Search

Three-dimensional carbon\\/silicon carbide composites were fabricated by chemical vapor infiltration, and the microstructure and mechanical properties were investigated. For the composites (CSiC) with no pyrolytic carbon interfacial layer, the mechanical properties (flexural strength, flexural elastic modulus, shear strength and fracture toughness) are increased with density of the composites. High density (p = 2.1 g cm?3) CSiC composites exhibit high fracture

Yongdong Xu; Litong Zhang; Laifei Cheng; Dantao Yan

1998-01-01

422

Chemical composition, antibacterial, antifungal and antioxidant activities of Algerian Eryngium tricuspidatum L. essential oil.  

PubMed

This study describes the chemical composition and the antibacterial, antifungal and antioxidant activities of the essential oil extracted from aerial parts of the Algerian Eryngium tricuspidatum L., obtained by hydrodistillation and analysed by using the combination of gas chromatography (GC) and GC/mass spectrometry. A total of 63 compounds were identified accounting for 93.1% of the total oil. Chemical composition of oil was characterised by a high proportion of oxygenated sesquiterpenes (49.6%) among which ?-bisabolol (32.6%) was the predominant compound. The sesquiterpene hydrocarbons represent the second major fraction (31.9%) with ?-curcumene (6.5%) being the predominant one. Antibacterial and antifungal activities of the oil were tested using the micro-well determination of minimum inhibitory concentration (MIC) assay against eleven bacteria and two Candida species. It was found that the aerial parts of E. tricuspidatum exhibited interesting antibacterial and anticandidal activities (MIC = 9 ?g/mL against several strains of bacteria and MIC = 4.6 ?g/mL against Candida albicans). The antioxidant effect of this oil was evaluated using the 2,2-diphenyl-l-1-picrylhydrazil (DPPH) and ferric reducing antioxidant power (FRAP) assays. Results revealed significant activities (DPPH method: IC50 = 510 ?g/mL; FRAP assay: reducing power of oil increases from 0.0188 at 5 ?g/mL to 0.5016 at 1000 ?g/mL). PMID:24559136

Merghache, Djamila; Boucherit-Otmani, Zahia; Merghache, Salima; Chikhi, Ilyas; Selles, Chaouki; Boucherit, Kebir

2014-06-01

423

Chemical composition and organoleptic evaluation of juice from steamed cashew apple blended with orange juice.  

PubMed

Fully riped cashew apples (yellow variety) were steamed for 7 minutes prior to juice extraction. The extracted juice was blended with various proportions of sweet orange juice. Chemical composition and organoleptic evaluation were carried out on both the blended and unblended juices. The ascorbic acid content of unsteamed cashew apple juice was 287 mg/100 ml. Steaming of the cashew apple prior to juice extraction resulted in a decreased (230 mg/100 ml) content of ascorbic acid. It also led to slight decreases in soluble solids and titratable acidity. A comparison of the chemical composition of the two juices showed that the orange juice contained more sugars, titratable acidity and soluble solids but less ascorbic acid than cashew apple juice. Consequently, the soluble solids, titratable acidity, reducing and total sugars of the blends increased with increase in the proportions of orange juice while the content of ascorbic acid was decreasing. In spite of the decrease in ascorbic acid content of the blends, results showed that blended juice would no doubt be a very good source of ascorbic acid. Result of the organoleptic evaluation revealed that a 60% cashew apple and 40% orange juice gave a good quality juice in terms of flavor, after taste and overall acceptability. PMID:9477424

Inyang, U E; Abah, U J

1997-01-01

424

Chemical composition and Zn bioavailability of the soil solution extracted from Zn amended variable charge soils.  

PubMed

A study on variable charge soils (volcanic Italian and podzolic Scottish soils) was performed to investigate the influence of soil properties on the chemical composition of soil solution. Zinc speciation, bioavailability and toxicity in the soil solution were examined. The soils were spiked with increasing amounts of Zn (0, 100, 200, 400 and 1000 mg/kg) and the soil solutions were extracted using rhizon soil moisture samplers. The pH, total organic carbon (TOC), base cations, anions, total Zn and free Zn2+ in soil solution were analysed. A rapid bioassay with the luminescent bacterium Escherichia coli HB101 pUCD607 was performed to assess Zn toxicity. The influence of soil type and Zn treatments on the chemical composition of soil solution and on Zn toxicity was considered and discussed. Different trends of total and free Zn concentrations, base cations desorption and luminescence of E. coli HB101 pUCD607 were observed. The soil solution extracted from the volcanic soils had very low total and free Zn concentrations and showed specific Zn2+/Ca2+ exchange. The soil solution from the podzolic soil had much higher total and free Zn concentrations and showed no evidence of specific Zn2+/Ca2+ exchange. In comparison with the subalkaline volcanic soils, the acidic podzol showed enhanced levels of toxic free Zn2+ and consequently stronger effects on E. coli viability. PMID:21174971

Zampella, Mariavittoria; Adamo, Paola

2010-01-01

425

Growth, chemical composition and soil properties of Tipuana speciosa (Benth.) Kuntze seedlings irrigated with sewage effluent  

NASA Astrophysics Data System (ADS)

This study was carried out at a greenhouse of Sabahia Horticulture Research Station, Alexandria, Egypt, to study the effect of sewage effluent on the growth and chemical composition of Tipuana speciosa (Benth.) Kuntze seedlings as well as on soil properties for three stages. The irrigation treatments were primary-treated wastewater and secondary-treated wastewater, in addition to tap water as control. Therefore, the treated wastewater was taken from oxidation ponds of New Borg El-Arab City. Results of these study revealed that the primary effluent treatment explored the highest significant values for vegetative growth and biomass, compared to the other treatments. In addition, the higher significant concentration and uptake of chemical composition in different plant parts were obtained from the primary effluent treatment during the three stages of irrigation. It was found that the concentration of heavy metals in either plant or soil was below as compared to the world-recommended levels. These findings suggested that the use of sewage effluent in irrigating T. speciosa seedlings grown in calcareous soil was beneficial for the improvement of soil properties and production of timber trees, and also important for the safe manner of disposal of wastewater.

Ali, Hayssam M.; Khamis, Mohamed H.; Hassan, Fatma A.

2012-06-01

426

What Do Microbes Encounter at the Plant Surface? Chemical Composition of Pea Leaf Cuticular Waxes1  

PubMed Central

In the cuticular wax mixtures from leaves of pea (Pisum sativum) cv Avanta, cv Lincoln, and cv Maiperle, more than 70 individual compounds were identified. The adaxial wax was characterized by very high amounts of primary alcohols (71%), while the abaxial wax consisted mainly of alkanes (73%). An aqueous adhesive of gum arabic was employed to selectively sample the epicuticular wax layer on pea leaves and hence to analyze the composition of epicuticular crystals exposed at the outermost surface of leaves. The epicuticular layer was found to contain 74% and 83% of the total wax on adaxial and abaxial surfaces, respectively. The platelet-shaped crystals on the adaxial leaf surface consisted of a mixture dominated by hexacosanol, accompanied by substantial amounts of octacosanol and hentriacontane. In contrast, the ribbon-shaped wax crystals on the abaxial surface consisted mainly of hentriacontane (63%), with approximately 5% each of hexacosanol and octacosanol being present. Based on this detailed chemical analysis of the wax exposed at the leaf surface, their importance for early events in the interaction with host-specific pathogenic fungi can now be evaluated. On adaxial surfaces, approximately 80% of Erysiphe pisi spores germinated and 70% differentiated appressoria. In contrast, significantly lower germination efficiencies (57%) and appressoria formation rates (49%) were found for abaxial surfaces. In conclusion, the influence of the physical structure and the chemical composition of the host surface, and especially of epicuticular leaf waxes, on the prepenetration processes of biotrophic fungi is discussed.

Gniwotta, Franka; Vogg, Gerd; Gartmann, Vanessa; Carver, Tim L.W.; Riederer, Markus; Jetter, Reinhard

2005-01-01

427

What do microbes encounter at the plant surface? Chemical composition of pea leaf cuticular waxes.  

PubMed

In the cuticular wax mixtures from leaves of pea (Pisum sativum) cv Avanta, cv Lincoln, and cv Maiperle, more than 70 individual compounds were identified. The adaxial wax was characterized by very high amounts of primary alcohols (71%), while the abaxial wax consisted mainly of alkanes (73%). An aqueous adhesive of gum arabic was employed to selectively sample the epicuticular wax layer on pea leaves and hence to analyze the composition of epicuticular crystals exposed at the outermost surface of leaves. The epicuticular layer was found to contain 74% and 83% of the total wax on adaxial and abaxial surfaces, respectively. The platelet-shaped crystals on the adaxial leaf surface consisted of a mixture dominated by hexacosanol, accompanied by substantial amounts of octacosanol and hentriacontane. In contrast, the ribbon-shaped wax crystals on the abaxial surface consisted mainly of hentriacontane (63%), with approximately 5% each of hexacosanol and octacosanol being present. Based on this detailed chemical analysis of the wax exposed at the leaf surface, their importance for early events in the interaction with host-specific pathogenic fungi can now be evaluated. On adaxial surfaces, approximately 80% of Erysiphe pisi spores germinated and 70% differentiated appressoria. In contrast, significantly lower germination efficiencies (57%) and appressoria formation rates (49%) were found for abaxial surfaces. In conclusion, the influence of the physical structure and the chemical composition of the host surface, and especially of epicuticular leaf waxes, on the prepenetration processes of biotrophic fungi is discussed. PMID:16113231

Gniwotta, Franka; Vogg, Gerd; Gartmann, Vanessa; Carver, Tim L W; Riederer, Markus; Jetter, Reinhard

2005-09-01

428

Effect of bio-regulator and foliar fertilizers on chemical composition and yield of soybean.  

PubMed

Current study evaluates the effects of bio-regulator associated with foliar fertilizers on the yield components, productivity and chemical composition of soybean. The experimental design was entirely randomized blocks, with four replications. The treatments consisted of: T1-absolute control, T2-application of 0.25 L h(-1) Stimulate in R1 stage of development, T3-application of 0.25 L h(-1) Stimulate and 3 L h(-1) Sett in R1, T4-application of 0.25 L h(-1) Stimulate and 3 L h(-1) Sett in R1 and 0.25 L h(-1) Stimulate and 2 L h(-1) Mover in R5.1; T5-application of 0.25 L h(-1) Stimulate and 3 L h(-1) Sett in R1 and 2 L h(-1) Mover in R5.1, T6-application of 3 L h(-1) Sett in R1 and 0.25 L h(-1) Stimulate and 2 L h(-1) Mover in R5.1 and T7-application of 0.25 L h(-1) Stimulate and 2 L h(-1) Mover in R1. Application of Sett and Mover is a potentially efficient handling as it favors the soybean agronomic performance in R1 stage. Chemical composition of processed grains has influence with applying bio-regulator and foliar fertilizers. PMID:24511692

Piccinin, Gleberson Guillen; Braccini, Alessandro Lucca; da Silva, Luiz Henrique; Mariucci, Giovanna Emanuêlle Gonçalves; Suzukawa, Andréia Kazumi; Dan, Lilian Gomes de Morais; Tonin, Telmo António

2013-11-15

429

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life.  

PubMed

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life were investigated in this study. In particular, the changes in antioxidants content, antioxidative and reducing capacity, and Maillard reaction development in rye ginger cakes after long-term storage were addressed. Ginger cakes produced according to the traditional and current recipe were stored for 5 years at room temperature in a dark place. The total phenolic compounds (TPC), inositol hexaphosphate (IP6), reduced (GSH) and oxidised glutathione (GSSG) contents, antioxidant and reducing capacity and Maillard reaction products (MRPs) were determined in ginger cakes after storage and then compared to those measured after baking. After long-term storage a decrease in TPC and IP6 contents in cakes was noted. In contrast, an increase in antioxidative and reducing capacity of stored cakes was observed. Long-term storage induced formation of furosine, advanced and final Maillard reaction products and caused changes in both reduced and oxidised forms of glutathione. After long-term storage the modest changes in furosine, FAST index and browning in ginger cake formulated with dark rye flour may suggest that this product is the healthiest among others. Therefore, traditional rye ginger cakes can be considered as an example of a healthy food that is also relatively stable during long term storage as noted by the small chemical changes observed in its composition. PMID:22980898

Zieli?ski, Henryk; del Castillo, Maria Dolores; Przygodzka, Ma?gorzata; Ciesarova, Zuzana; Kukurova, Kristina; Zieli?ska, Danuta

2012-12-15

430

Seasonal Variation, Chemical Composition and Antioxidant activity of Brazilian Propolis Samples  

PubMed Central

Total phenolic contents, antioxidant activity and chemical composition of propolis samples from three localities of Minas Gerais state (southeast Brazil) were determined. Total phenolic contents were determined by the Folin–Ciocalteau method, antioxidant activity was evaluated by DPPH, using BHT as reference, and chemical composition was analyzed by GC/MS. Propolis from Itapecerica and Paula Cândido municipalities were found to have high phenolic contents and pronounced antioxidant activity. From these extracts, 40 substances were identified, among them were simple phenylpropanoids, prenylated phenylpropanoids, sesqui- and diterpenoids. Quantitatively, the main constituent of both samples was allyl-3-prenylcinnamic acid. A sample from Virginópolis municipality had no detectable phenolic substances and contained mainly triterpenoids, the main constituents being ?- and ?-amyrins. Methanolic extracts from Itapecerica and Paula Cândido exhibited pronounced scavenging activity towards DPPH, indistinguishable from BHT activity. However, extracts from Virginópolis sample exhibited no antioxidant activity. Total phenolic substances, GC/MS analyses and antioxidant activity of samples from Itapecerica collected monthly over a period of 1 year revealed considerable variation. No correlation was observed between antioxidant activity and either total phenolic contents or contents of artepillin C and other phenolic substances, as assayed by CG/MS analysis.

Teixeira, Erica Weinstein; Message, Dejair; Negri, Giuseppina; Stringheta, Paulo Cesar

2010-01-01

431

Larvicidal efficacies and chemical composition of essential oils of Pinus sylvestris and Syzygium aromaticum against mosquitoes  

PubMed Central

Objective To assess the chemical composition and mosquito larvicidal potentials of essential oils of locally sourced Pinus sylvestris (P. sylvestris) and Syzygium aromaticum (S. aromaticum) against Aedes aegypti (A. aegypti) and Culex quinquefasciatus (C. quinquefasciatus). Method The chemical composition of the essential oils of both plants was determined using GC-MS while the larvicidal bioassay was carried out using different concentrations of the oils against the larvae of A. aegypti and C. quinquefasciatus in accordance with the standard protocol. Results The results as determined by GC-MS showed that oil of S. aromaticum has eugenol (80.5%) as its principal constituent while P. sylvestris has 3-Cyclohexene-1-methanol, .alpha., .alpha.4-trimethyl (27.1%) as its dominant constituent. Both oils achieved over 85% larval mortality within 24 h. The larvae of A. aegypti were more susceptible to the oils [LC50 (S. aromaticum)=92.56 mg/L, LC50(P. sylvestris)=100.39 mg/L] than C. quinquefasciatus [LC50(S. aromaticum)=124.42 mg/L; LC50(P. sylvestris)=128.00 mg/L]. S. aromaticum oil was more toxic to the mosquito larvae than oil of P. sylvestris but the difference in lethal concentrations was insignificant (P>0.05). Conclusion The results justify the larvicidal potentials of both essential oils and the need to incorporate them in vector management and control.

Fayemiwo, Kehinde Adenike; Adeleke, Monsuru Adebayo; Okoro, Ovie Princewill; Awojide, Shola Hezekiah; Awoniyi, Ilias Olufemi

2014-01-01

432

Effect of chemical composition and density of the pelvic structure in intracavitary brachytherapy dosimetry  

NASA Astrophysics Data System (ADS)

High dose rate (HDR) and low dose rate (LDR) intracavitary brachytherapies dosimetry in clinical practice are typically performed by commercial treatment planning systems. However, these systems do not fully consider the heterogeneities present in the real structure of the patient. The aim of this work is to obtain isodose curves and surfaces around the usual array of sources used in LDR ( 137Cs) and HDR ( 192Ir) intracavitary brachytherapy by Monte Carlo simulation, considering the real anatomic structure, density and chemical composition of media and tissues from the female pelvic region. The structural information was obtained from computed tomography images in the DICOM format. A voxel phantom (VP) was developed to perform ionizing radiation transport, considering the gamma spectrum of 137Cs and 192Ir. The absorbed dose was computed within each voxel of 2×2×3 mm 3. Four materials were considered in the VP—air, fat, muscle tissue and bone; however, one material per voxel was defined. Results show and quantify the effect of density and chemical composition of the medium on the absorbed dose distribution. According to them, the treatment planning systems underestimate the absorbed dose by 8% approximately for both ra