Schnelle fluorimetrische Bestimmung von Chlortetracyclin in Fleisch und Knochen

Zusammenfassung Antibiotica, einschließlich der Tetracycline, werden in biologischem Material üblicherweise mit mikrobiologischen Methoden bestimmt. Die Unspezifität und der große Zeitaufwand der mikrobiologischen Tests veranlaßten uns, einen fluorimetrischen Test auszuarbeiten, der spezifisch Tetracyclin-Antibiotica erfaßt und innerhalb von 4 Std ein Ergebnis liefert. Grundlage des Tests ist die von Kohn (1961) beschriebene Methode, die in modifizierter Form auf Chlortetracyclin in Fleisch und Knochen angewendet wurde. Tetracycline sind fluorescierende Substanzen, deren Quantenausbeute in vielen Fällen durch komplex gebundene Ca²⁺Ionen und Überführung des Komplexes in organische Lösungsmittel stark erhöht wird. Durch die Extraktion in die organische Phase werden störende Substanzen abgetrennt. Die Ausbeute an Chlortetracyclin mit der beschriebenen Methode liegt bei 80%, die Empfindlichkeit bei 0,5 ppm.

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Fast fluorimetric assay of chlortetracycline in meat and bone

Summary Antibiotics in biological materials, including tetracyclines, are determined usually be means of microbiological methods. Because of the low specificity and the time consuming procedure of the microbiological assays, we developed a fluorimetric method, which enables us to determine specifically the tetracyclines and to reduce the time for the assay down to 4 hours. Our method is based on the determination of tetracyclines published by Kohn (1961), which we modified for the determination of chlortetracycline in meat and bone. Tetracyclines are fluorescent compounds, whose quantum yields are very much enhanced in most cases by forming a complex with Ca²⁺ ions and by extracting it into an organic solvent. This transfer into acetic acid ethylester separates the chlortetracycline from interfering substances. The yield of chlortetracycline with the described method was about 80%, the sensitivity of the detection was about 0.5 ppm.

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H. Hambloch führte die Untersuchungen über Chlortetracyclin in Knochen als Abschlußarbeit zur Erlangung des Grades Ingenieur (grad) der Fachhochschule Lippe, Lemgo, an der Bundesanstalt für Fleischforschung, Kulmbach, durch

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Frau H. Sauer danken wir an dieser Stelle für ihre zuverlässige technische Mitarbeit     

Steam volatile aroma constituents of roasted coffee: Neutral fraction

The volatile components of roasted coffee, isolated by normal-pressure steam distillation, were separated into basic and neutral fractions. The neutral fraction was analysed on a UCON HB 5100 glass capillary column (200 m x 0.31 mm W.) coupled to a low-resolution mass spectrometer. One hundred and twenty compounds were identified, of which twenty-six had not been previously reported in coffee aroma. Identification of the structures of the newly identified compounds was accomplished by comparison of their mass spectra with reference spectra. GLC retention times were used to confirm identifications. The new compounds identified for the first time in roasted coffee include 15 furans, 6 pyrroles, 3 thiophenes, and 2 ketones. Of the 15 furans eight methylvinylfurans, dimethyl-vinylfurans and alkenylfurans, which had not been previously found in roasted foodstuffs, should be specially mentioned.Mass-spectral data of the newly identified substances are tabulated. Fragmentation patterns of N-acetyl-2-methylpyrrole, N-furfuryl-2-methylpyrrole, 2-vinyl-3-methylfuran and 2-vinyl-3,5-dimethylfuran are discussed. Comments are made with respect to possible formation patterns and precursors in green coffee beans.     

Non-invasive blood perfusion measurements using a combined temperature and heat flux surface probe

Non-invasive blood perfusion measurement systems have been developed and tested in a phantom tissue and an animal model. The probes use a small sensor with a laminated flat thermocouple to measure the heat transfer and temperature response to an arbitrary thermal event (convective or conductive) imposed on the tissue surface. Blood perfusion and thermal contact resistance are estimated by comparing heat flux data with a mathematical model of the tissue. The perfusion probes were evaluated for repeatability and sensitivity using both a phantom tissue test stand and exposed rat liver tests. Perfusion in the phantom tissue tests was varied by controlling the flow of water into the phantom tissue test section, and the perfusion in the exposed liver tests was varied by temporarily occluding blood flow through the portal vein. The phantom tissue tests indicated that the probes can be used to detect small changes in perfusion (0.005 ml/ml/s). The probes qualitatively tracked the changes in the perfusion of the liver model due to occlusion of the portal vein.     

Cochlear and Brainstem Auditory Prostheses “Neural Interface for Hearing Restoration: Cochlear and Brain Stem Implants”

This paper discusses the development and implementation of three novel implantable technologies that have advanced the communication abilities of hearing-impaired individuals who cannot benefit from conventional hearing aids. This paper will discuss clinical indications and outcomes and include current technological limitations and future research efforts.     

The measurement and prediction of the solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution

The solubility of mixtures of carbon dioxide and hydrogen sulphide in a 2.5 N monoethanolamine solution has been determined at temperatures of 40°C and 100°C. Partial pressures of CO₂ ranged from 0.7 to 5630 kPa, while partial pressures of H₂S ranged from 0.7 to 3780 kPa. The present results extend the published data on this system which were limited to partial pressures below 200 kPa. The results have been compared with two methods of prediction based upon a thermodynamic model.     

Schlagregensicherheit von Steildachkonstruktionen – europäische und nationale Bewertungsverfahren für den Regeneintrag in gedeckte Dächer und die Schlagregensicherheit von Unterdeck‐ und Unterspannbahnen

Resistance to driving rain of pitched roof structures ‐ German and European assessment methods for rain penetration into tiled roofs and the resistance to driving rain of covering underlays and self supporting underlays. Resistance to driving rain describes the ability of an external component to offer protection against ingress of water into the component or the building under specified wind force, rainfall and rain duration. Standardised tests already exist for assessing and classifying the resistance to driving rain of components such as windows, external doors and gates, while for covered pitched roof structures no such tests have been established as yet. This applies to the actual roof covering consisting of small‐sized roofing elements such as tiles as well as covering underlays and self supporting underlays, which are exposed to the weather during the construction phase and during alterations or refurbishment. Over recent years great efforts have been made to try and compare the resistance to driving rain of covered pitched roof structures and exposed covering underlays and self supporting underlays used as temporary roof covering.     

Computer Simulation of the Microstructure Developed in Reaction-Sintered Silicon Nitride Ceramics

A simulation model of the microstructure developed during the reaction sintering of ultrafine silicon powders is presented. The model employs interactive subroutines that describe particle compaction, sintering, and nitridation. The particle compaction model is based on a random particle packing model, whereas the sintering and reaction sintering models are based on the modified grain model and the sharp interface model (SIM). Microstructural changes due to the competition between chemical reaction and sintering are taken into account in the model. The results predicated by this model show good agreement with experimental data from previous studies.     

Negro-white differences in intelligence test performance: A new look at an old problem.

Negro-white differences on mental tests are evaluated in this paper, which was prepared at the suggestion of the Society for the Psychological Study of Social Issues (Division 9 of the American Psychological Association). "The evidence against the assumption of native differences in intelligence test performance between Negroes and whites still seems to me to be very convincing." There is "no scientifically acceptable evidence for the view that ethnic groups differ in innate abilities. This is not the same as saying that there are no ethnic differences in such abilities… . The science of psychology can offer no support to those who see in the accident of inherited skin color or other physical characteristics any excuse for denying to individuals the right to full participation in American democracy." (PsycINFO Database Record (c) 2010 APA, all rights reserved)