Design and use of a collector for the in situ isolation of particulate trace organic species in precipitation     

M. A. Mazurek  B. R. T. Simoneit  L. J. Standley  D. Friedman  C. Beeman 《Water, air, and soil pollution》1987,36(1-2):171-192

Extracts of particulate organic matter were examined for discrete rainfall events from metropolitan Los Angeles, California, using an in situ filtration technique. Filtration efficiency was 98 % for the collection of extractable organic C associated with particles having nominal diameters greater than 0m22 μm Organic background levels of less than 260 ng per sample were determined. Rainwater particle samples were extracted with repeated hexane and benzene: isopropanol (2: 1) solvent additions using ultrasonic agitation. Extract mixtures were quantified by high-resolution gas chromatography (HRGC) and were adjusted for component losses with perdeuterated recovery standards. Yields for the neutral fractions ranged from 130 to 669 μg with flux rates corresponding to 371 to 1097μg m^?2 day^?1. Aliquots of the neutral solvent extracts were derivatized with diazomethane to convert acidic hydroxy and carboxylic acid groups to the respective methyl ether and methyl ester analogs. This step produced increased yields of 8 to 188 %, and resulted in yields for the acid +neutral extracts that ranged from 374 to 8681μg with flux rates of 591 to 2343 μg m^?2 day^?1. Source identification was conducted by high-resolution gas chromatography/mass spectrometry (HRGC/MS) analyses. Molecular analyses indicated major anthropogenic contributions from petroleum and combustion sources, and for some samples, the significant input of microbial lipid components as well. Minor amounts of vascular plant waxes were also present in most cases. These mixed inputs of both anthropogenic and biogenic materials compared closely with previous source determinations for carbonaceous aerosol particles in the Los Angeles air basin.  相似文献   

Measures for interoperability of phenotypic data: minimum information requirements and formatting     

Hanna??wiek-Kupczyńska  Thomas?Altmann  Daniel?Arend  Elizabeth?Arnaud  Dijun?Chen  Guillaume?Cornut  Fabio?Fiorani  Wojciech?Frohmberg  Astrid?Junker  Christian?Klukas  Matthias?Lange  Cezary?Mazurek  Anahita?Nafissi  Pascal?Neveu  Jan?van?Oeveren  Cyril?Pommier  Hendrik?Poorter  Philippe?Rocca-Serra  Susanna-Assunta?Sansone  Uwe?Scholz  Marco?van?Schriek  ümit?Seren  Bj?rn?Usadel  Stephan?Weise  Paul?Kersey  Pawe??KrajewskiEmail author 《Plant methods》2016,12(1):44

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Reduced numbers of somatostatin receptors in the cerebral cortex in Alzheimer's disease   总被引：9，自引：0，他引：9  

M F Beal  M F Mazurek  V T Tran  G Chattha  E D Bird  J B Martin 《Science (New York, N.Y.)》1985,229(4710):289-291

Somatostatin receptor concentrations were measured in patients with Alzheimer's disease and controls. In the frontal cortex (Brodmann areas 6, 9, and 10) and temporal cortex (Brodmann area 21), the concentrations of somatostatin in receptors in the patients were reduced to approximately 50 percent of control values. A 40 percent reduction was seen in the hippocampus, while no significant changes were found in the cingulate cortex, postcentral gyrus, temporal pole, and superior temporal gyrus. Scatchard analysis showed a reduction in receptor number rather than a change in affinity. Somatostatin-like immunoreactivity was significantly reduced in both the frontal and temporal cortex. Somatostatin-like immunoreactivity was linearly related to somatostatin-receptor binding in the cortices of Alzheimer's patients. These findings may reflect degeneration of postsynaptic neurons or cortical afferents in the patients' cerebral cortices. Alternatively, decreased somatostatin-like immunoreactivity in Alzheimer's disease might indicate increased release of somatostatin and down regulation of postsynaptic receptors.  相似文献   

Organic Tracers from Wild Fire Residues in Soils and Rain/River Wash-Out     

Oros  Daniel R.  Mazurek  Monica A.  Baham  John E.  Simoneit  Bernd R. T. 《Water, air, and soil pollution》2002,137(1-4):203-233

The molecular compositions and alteration products of the major organic components in soils and litter subjected to controlled or wildfire burning, and subsequent erosion by rain and river transport have been determined by GC-MS. The major compound groups imparted to soils include n-alkanoic acids, n-alkanes, n-alkanols, phytosterols, and terpenoids. Biomarker tracer analysis indicates that organic compounds remain as internal lipid components of char and heavy particles and are deposited onto soil during wildfire and prescribed burning. The process of rain erosion and river transport releases some of these internal components into the surroundings where they are further subjected to biological alteration. The distributions and abundances ofhomologous compound series coupled with biomarker tracer analysis provides a chemical fingerprint which is useful for identifying the single or multiple plant species contributing organic matter by both thermal (burning) and biological processes. Such fingerprints are useful for tracking soils which are transported in the atmosphere by wind as suspended particles in dust storms and on land by rain erosion to rivers.  相似文献