PIXE measurements of Kr-sputtered TiN coatings

Titanium nitride films of 30–300 nm thickness deposited via dc magnetron sputtering were irradiated with 150–700 keV Kr ions at fluences up to 2.1 × 10¹⁷ cm⁻². These films were then scanned with a well-collimated 400 keV proton beam and the X-ray yield of Ti was measured both in and outside the Kr beam spot. This procedure results in a precision determination of the average film thickness (± 1% in the case of tens of nm films). The PIXE results are found to be consistent with RBS data of the same specimens. Sputtering yields were determined from the variation of X-ray yields assuming unchanged Ti/N stoichiometry in the implanted area. For thick TiN films (d₀ > 100 nm) the sputtering yields are in good agreement with predictions of the collisional cascade model by Sigmund. In contrast, sputtering of thin layers (d₀ = 30 nm) depended sensitively on the ion energy, being a factor of 2 higher at 150 keV than at 500 keV.     

Proteindifferenzierung mit elektrophoretischen Methoden bei Fleisch, Fisch und abgeleiteten Produkten

Zusammenfassung Die Untersuchung von wäßrigen Extrakten aus rohen Wurstbräten ergab, daß der Zusatz rezepturüblicher Mengen an Speck, Kochsalz, Natriumdiphosphat, Natriumcitrat und Gewürzmischungen zu zerkleinertem Skelettmuskel die Proteinmuster nicht verändert und auch die Identifizierung der Tierart in binären Mischungen nicht beeinträchtigt. Wäßrige Extrakte aus Innereien liefern organ- und tierartspezifische Proteinmuster. Vor- und Nachteile bei der Verwendung von Fertigplatten und selbstgegossenen Platten werden diskutiert.

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Protein differentiation with electrophoretic methods in meat, fish and derived productsIV. Analysis of Raw Sausage Mixtures and Offals by Mean of Isoelectric Focusing in Polyarylamide Gels, Using Commercial Plates and Plates, Prepared in the Laboratory

Summary The protein patterns obtained by isoelectric focusing of aqueous extracts of minced meat are not changed by addition of bacon, salt, sodiumdiphosphate, sodiumcitrate and spices in amounts usual in sausage manufacturing. An identification of the animal species in binary mixtures is also possible in presence of the additives. With aqueous extracts of offal protein patterns are obtained which are specific for both the animal species and the organ. Advantages and disadvantages of commercial plates and gel plates prepared in the laboratory are discussed.

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III. Mitteilung: Kaiser et al. [l]     

An invariance principle for maintaining the operating point of a neuron

Sensory neurons adapt to changes in the natural statistics of their environments through processes such as gain control and firing threshold adjustment. It has been argued that neurons early in sensory pathways adapt according to information-theoretic criteria, perhaps maximising their coding efficiency or information rate. Here, we draw a distinction between how a neuron's preferred operating point is determined and how its preferred operating point is maintained through adaptation. We propose that a neuron's preferred operating point can be characterised by the probability density function (PDF) of its output spike rate, and that adaptation maintains an invariant output PDF, regardless of how this output PDF is initially set. Considering a sigmoidal transfer function for simplicity, we derive simple adaptation rules for a neuron with one sensory input that permit adaptation to the lower-order statistics of the input, independent of how the preferred operating point of the neuron is set. Thus, if the preferred operating point is, in fact, set according to information-theoretic criteria, then these rules nonetheless maintain a neuron at that point. Our approach generalises from the unimodal case to the multimodal case, for a neuron with inputs from distinct sensory channels, and we briefly consider this case too.     

A Petri net model for integrated process and job shop production planning

In this paper a new Petri net class (Chameleon systems) for modeling and analyzing joined process planning and job shop production planning is proposed based on the multi-level Petri net model introduced by Valk (1995). Chameleon system is a High-level Petri net extended with time that consists of a High-level Petri net modeling the workshop which is called system net and ordinary Petri net modeling the jobs and setups which act as tokens of the system net and therefore are called token nets. Process plans of the jobs are partial orders of operation groups and alternatives. The uncertainty of operation duration is captured by a new time model. The advantages of this new modeling approach are the following: (i) a modular construction of the joined process and job shop planning is allowed, (ii) classical known Petri net analysis methods can be applied and (iii) the analysis can be done at different levels of abstraction.     

Monitoring Cheddar cheese ripening by chemical indices of proteolysis 3. Identification of several high-molecular mass peptides

Summary Two Cheddar cheeses from two different production plants were ripened over 24 weeks at 10° C and then analysed for peptides soluble in citrate buffer at pH 4.6 by reversed-phase (RP)-HPLC. Thirteen peptides with a chain length of between 35 and 65 amino acid residues and molecular masses between 3800 and 7400 were isolated and assigned to the corresponding amino acid sequences of the casein fractions via Edman degradation and amino acid composition. All peptides were fragments of the region K²⁹-S⁹⁶ of-caseine A¹ and A², and eleven of them had M⁹³ as the C-terminal. The amounts and proportions of these peptides varied differently during ripening of the two cheeses, so they may be suitable markers for characterizing the stage of ripening

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Beurteilung des Reifungsverlaufs in Cheddarkäse durch chemische Indikatoren des Eiweißabbaus. 3. Identifizierung einiger größerer Peptide

Zusammenfassung Zwei Cheddarkäse aus zwei verschiedenen Fabriken wurden 24 Wochen bei 10° C gereift und dann durch RP-HPLC auf in Citratpuffer bei pH 4,6 lösliche Peptide analysiert. Dreizehn Peptide mit Kettenlängen zwischen 35 und 65 Aminosäureresten und Molmassen zwischen 3800 und 7400 wurden isoliert und den korrespondierenden Sequenzen der Caseinfraktionen über Edman-Abbau und Aminosäurezusammensetzung zugeordnet. Alle Peptide erwiesen sich als Fragmente der-Caseine A¹ und A² aus der Region K²⁹-S⁹⁶, und elf von ihnen endeten mit M⁹³ als C-Terminus. Da die Mengen und Proportionen dieser Peptide sich im Verlauf der Reifung der zwei Käse unterschiedlich ändern [cf. Z Lebensm Unters Forsch (1992) 195:8], dürften sie als Indikatoren zur Charakterisierung des Reifungszustandes brauchbar Sein.

     

Nachweis von Kuhmilch in Schaf- und Ziegenmilch bzw. -k?se durch isoelektrische Focussierung in harnstoffhaltigen Polyacrylamidgelen

Summary Addition of cow's milk to sheep's and goat's milk or cheese can be detected by isoelectric focusing of acid caseins on thin layers of polyacrylamide gels containing 6 M urea. From densitometric evaluation of protein pherograms, taking a-casein as indicator protein, presence of cow's milk can be determined with confidence down to a level of 2 or 1% in sheep's or goat's milk. Some commercially available cheeses from goat's or sheep's milk were found to contain large amounts of cow's milk. Advantages of the present method as compared to immunological methods are discussed.Zusammenfassung Ein Zusatz von Kuhmilch zu Schaf und Ziegenmilch oder -käse kann durch isoelektrische Focussierung der Säurecaseine auf dünnen, harnstoff haltigen Polyacrylamidgelen (PAGIF) nachgewiesen werden. Bei quantitativer, densitometrischer Auswertung der Pherogramme unter Verwendung eines-Caseins als Indikatorprotein l:aßt sich Kuhmilch in Schaf oder Ziegenmilch bis herab zu 2 bzw. 1% sicher nachweisen. In einigen Ziegen- und Schafkäsen des Handels konnte die Verwendung von Kuhmilch eindeutig festgestellt werden. Vorteile dieser Methode gegenüber den immunologischen Verfahren werden erörtert.     

Anti-inflammatory prodrugs as plasticizers for biodegradable implant materials based on poly(3-hydroxybutyrate)

Salicylic and acetylsalicylic acid esters were tested as plasticizers for biodegradable poly(3-hydroxybutyrate) (PHB). The aim is the combination of plasticizing and anti-inflammatory properties in the fabrication of implant materials. Solution-cast films made of mixtures of PHB and 30% ester showed plasticization accompanied by a decrease of elastic modulus and an increase in elongation at break in comparison with pure PHB films. However, the number of usable plasticizers from the group of the salicylic acid and acetylsalicylic acid esters is limited. Short-chain derivatives are volatile while long-chain compounds tend to crystallize. In both cases PHB films embrittle within short time. Moreover, some derivatives show a fast release in an aqueous environment. As alternative nonsteroidal anti-inflammatory prodrugs arylpropionic acid esters were tested as plasticizers. The addition of ketoprofen ethyl ester led to PHB films with decreased brittleness. In summary, various esters of anti-inflammatory drugs show plasticizing effects on solution-cast PHB films comparable with those of commonly used citric acid esters.     

Retrieval of profile information from airborne multiaxis UV-visible skylight absorption measurements

A recent development in ground-based remote sensing of atmospheric constituents by UV-visible absorption measurements of scattered light is the simultaneous use of several horizon viewing directions in addition to the traditional zenith-sky pointing. The different light paths through the atmosphere enable the vertical distribution of some atmospheric absorbers, such as NO2, BrO, or O3, to be retrieved. This approach has recently been implemented on an airborne platform. This novel instrument, the airborne multiaxis differential optical absorption spectrometer (AMAXDOAS), has been flown for the first time. In this study, the amount of profile information that can be retrieved from such measurements is investigated for the trace gas NO2. Sensitivity studies on synthetic data are performed for a variety of representative measurement conditions including two wavelengths, one in the UV and one in the visible, two different surface spectral reflectances, various lines of sight (LOSs), and for two different flight altitudes. The results demonstrate that the AMAXDOAS measurements contain useful profile information, mainly at flight altitude and below the aircraft. Depending on wavelength and LOS used, the vertical resolution of the retrieved profiles is as good as 2 km near flight altitude. Above 14 km the profile information content of AMAXDOAS measurements is sparse. Airborne multiaxis measurements are thus a promising tool for atmospheric studies in the troposphere and the upper troposphere and lower stratosphere region.