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Berlin Brandenburg

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  • 1
    Language: English
    In: Proceedings of the National Academy of Sciences of the United States of America, 19 May 2015, Vol.112(20), pp.6325-30
    Description: High-volume hydraulic fracturing (HVHF) has revolutionized the oil and gas industry worldwide but has been accompanied by highly controversial incidents of reported water contamination. For example, groundwater contamination by stray natural gas and spillage of brine and other gas drilling-related fluids is known to occur. However, contamination of shallow potable aquifers by HVHF at depth has never been fully documented. We investigated a case where Marcellus Shale gas wells in Pennsylvania caused inundation of natural gas and foam in initially potable groundwater used by several households. With comprehensive 2D gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS), an unresolved complex mixture of organic compounds was identified in the aquifer. Similar signatures were also observed in flowback from Marcellus Shale gas wells. A compound identified in flowback, 2-n-Butoxyethanol, was also positively identified in one of the foaming drinking water wells at nanogram-per-liter concentrations. The most likely explanation of the incident is that stray natural gas and drilling or HF compounds were driven ∼ 1-3 km along shallow to intermediate depth fractures to the aquifer used as a potable water source. Part of the problem may have been wastewaters from a pit leak reported at the nearest gas well pad-the only nearby pad where wells were hydraulically fractured before the contamination incident. If samples of drilling, pit, and HVHF fluids had been available, GCxGC-TOFMS might have fingerprinted the contamination source. Such evaluations would contribute significantly to better management practices as the shale gas industry expands worldwide.
    Keywords: Marcellus Shale ; High-Volume Hydraulic Fracturing ; Natural Gas ; Shale Gas ; Water Quality ; Water Movements ; Extraction and Processing Industry -- Methods ; Groundwater -- Chemistry ; Natural Gas -- Adverse Effects ; Water Pollutants, Chemical -- Analysis ; Water Supply -- Analysis
    ISSN: 00278424
    E-ISSN: 1091-6490
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  • 2
    In: Journal of the Chemical Society (Resumed), 1956, pp.4481-4487
    ISSN: 0368-1769
    Source: Royal Society of Chemistry
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  • 3
    In: Journal of the Chemical Society (Resumed), 1954, pp.4269-4275
    ISSN: 0368-1769
    Source: Royal Society of Chemistry
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  • 4
    In: Journal of the Chemical Society (Resumed), 1958, pp.611-613
    ISSN: 0368-1769
    Source: Royal Society of Chemistry
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  • 5
    Language: English
    In: Journal of Pharmaceutical Analysis, 01 December 2013, Vol.3(6), pp.509-517
    Description: Two common analytical chemical problems often encountered when using chromatographic techniques in drug analysis are matrix interferences and ion suppression. Common sample preparation often involves the dilution of the sample prior to injection...
    Keywords: Pharmacy, Therapeutics, & Pharmacology
    ISSN: 2095-1779
    E-ISSN: 2214-0883
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  • 6
    Language: English
    In: American journal of public health, January 1990, Vol.80(1), pp.50-3
    Description: After the Food and Drug Administration approved a topical antibiotic for the treatment of acne, we began a postmarketing surveillance study to measure the frequency of antibiotic-associated colitis and diarrhea in acne patients treated with topical antibiotics and low doses of oral antibiotics. Pharmacists recruited 13,465 patients who presented a prescription for an acne medication, and we obtained detailed information on the use of the medications, perceived acceptability, and the occurrence of new health events from 6,453 with computer-assisted telephone interviews. Three cases (less than 0.1%) of antibiotic-associated diarrhea and one case (less than 0.1%) of antibiotic-associated colitis were confirmed. We conclude that this methodology can provide further information about the safety of a drug once it is in customary use, at a fraction of the cost of Phase III clinical trials.
    Keywords: Acne Vulgaris -- Drug Therapy ; Anti-Bacterial Agents -- Adverse Effects ; Colitis -- Chemically Induced ; Diarrhea -- Chemically Induced ; Product Surveillance, Postmarketing -- Methods
    ISSN: 0090-0036
    E-ISSN: 15410048
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  • 7
    Language: English
    In: Clinical Microbiology and Infection, February 2005, Vol.11(2), pp.122-130
    Description: The rapid technique of pyrosequencing was used to examine 123 samples (in the form of DNA extracts and inactivated sputum) of spp. Of 99 samples investigated for single-nucleotide polymorphisms (SNPs), 68% of isoniazid-resistant isolates analysed had an AGC → ACC mutation in at codon 315, resulting in the Ser → Thr substitution associated previously with isoniazid resistance. Of the rifampicin-resistant isolates, 92% showed SNPs in at codons 516, 531 or 526. Inactivated sputum samples and DNA extracts could both be analysed by pyrosequencing, and the method was able to differentiate rapidly between the closely related species of the complex ( and ), except between and one of two strains. This low-cost, high-throughput technique could be used as a rapid screen for drug resistance and as a replacement for some of the time-consuming tests used currently for species identification.
    Keywords: Antibiotic Susceptibility Testing ; Identification ; Mycobacterium Tuberculosis Complex ; Pyrosequencing ; Resistance ; Medicine ; Biology
    ISSN: 1198-743X
    E-ISSN: 1469-0691
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  • 8
    Language: English
    In: Journal of the American Chemical Society, 05/1957, Vol.79(10), pp.2385-2390
    ISSN: 0002-7863
    E-ISSN: 1520-5126
    Source: American Chemical Society (via CrossRef)
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  • 9
    In: Canadian Journal of Chemistry (Revue canadienne de chimie), 1961, Vol.39(2), pp.324-330
    Description: Measurement of the transmission of electronic effects through square-planar complexes of platinum has provided evidence of double bonding to halogen and nitro ligands. The nuclear magnetic resonance chemical shift of the -protons in pyridine ligands serves as an indicator of electron drift in the complexes. Justification is thus provided for the assumed mechanism of the trans effect involving -bonding. The observations are in accord with the assumption that the increase in trans-directing powers with atomic number of the halogen is due to an increasing tendency to accept d -electrons from the central atom.
    Description: non disponible
    Keywords: Chemistry;
    ISSN: 0008-4042
    E-ISSN: 1480-3291
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  • 10
    Language: English
    In: Talanta, 1960, Vol.3(4), pp.364-369
    Description: A study of the recorded method for the determination of platinum with dimethylphenyl-benzylammonium chloride revealed defects which become serious for larger amounts. A revised procedure which yields accurate results for micro and semi-micro amounts is described. Samples which have been fumed in sulphuric acid solution may be handled with a slight modification of the recommended procedure. Die von Ryan veröffentlichte Methode zur gewichtsanalytischen Bestimmung von Platin mit Dimethylphenylbenzylammoniumchlorid wurde eingehender untersucht und die für grössere Platinmengen Fehlerquellen festgestellt. Eine modifizierte Methode, welche für den Mikrosowie Halbmikro-bereich genaue Resultate erziehlt, wird beschrieben. Platinlösungen welche mit Schwefelsäure abgeraucht wurden, können mit kleinen Änderungen untersucht werden. La méthode de Ryan utilisant le chlorure de dimethyl phénylbenzylammonium pour le micro dosage du platine s'est révélée défectueuse et d'autant plus si les quantités sont grandes. Une modification de cette méthode fourni des résultats aussi précis à l'échelle micro que semi-micro. Même, si l'échantillon est digéré dans une solution sulfurique on peut le traiter en modifiant legérèment le processus opératoire.
    Keywords: Chemistry
    ISSN: 0039-9140
    E-ISSN: 1873-3573
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