Die Kristall- und MolekülStruktur von N,N′-Bis-(trimethylsilyl)-oximidsäure-bis(trimethylsilyl)-ester

The Crystal and Molecular Structure of N,N′-Bis(trimethylsilyl) Oximidic Acid Bis (trimethylsilyl) Ester The X-ray structure analysis of the reaction product of oxalyl chloride with sodium bis(trimethylsilyl) amide formulated by PUMP and ROCHOW as N,N′-bis(trimethylsilyl) oximidic Acid bis (trimethylsilyl) ester shows that the suggested structure is correct for the solid state. The compound crystallizes in the space group P1 with a = 9.948(4), b = 6.612(3), c = 10.370(4) Å, α = 88.87(6), β = 116.95(4), γ = 98.23(6)°, and Z = 1. The molecule manifests symmetry 1 .     

Synthesis and PET oxidative cyclization of silyl enol ethers: build-up of quasi-steroidal carbocycles

PET oxidative cyclization of silyl enol ethers carrying suitable side chains with olefinic double bonds results in the stereoselective formation of carbocycles. Two model compounds for investigating the influence of silyl enol ether ring size are synthesized. Furthermore the synthesis of a quasi-steroidal carbocycle with an unnatural configuration is presented.     

Spektroskopische Untersuchungen an Schwefelverbindungen. VII. 1H- und 13C-NMR-spektroskopische Untersuchungen an Alkansulfinsäurechloriden und Chloroschwefligsäurealkylestern

Spectroscopic Studies on Sulphur Compounds. VII. ¹H- and ¹³C-NMR Spectroscopic Investigations of Sulphinic Acid Chlorides and Chloro-sulphurous Acid Alkylesters The temperature dependent ¹H- and ¹³C-n.m.r. spectra of the sulphinic acid chlorides R—S(O)Cl and of the chloro-sulphurous acid alkylesters RO—S(O)Cl with R = CH₃CH₂- and (CH₃)₂CH- have been measured. The differing behaviour of both nuclei is discussed in terms of inversion at the chiral sulphur atom.     

Untersuchungen über optionale Präventivstrategien in der Instandhaltung

Zusammenfassung Optionale Präventivstrategien sind solche, die vorbeugende Erneuerungen nur gelegentlich eines nicht ausfallbedingten Anlagenstillstands (etwa Unterbrechungen in der Energieoder Materialversorgung, Serienumstellung, Schichtende) zulassen, ohne daß jedoch bei jeder dieser Gelegenheiten erneuert werden muß. Ein zweckmäßiges Entscheidungskriterium dafür, ob beim Eintritt einer Erneuerungsgelegenheit vorbeugend erneuert werden soll oder nicht, ist das momentane Alter der Anlage. Im einzelnen enthält der Aufsatz: 1. den Nachweis, daß es eine optionale Präventivstrategie gibt, die kostengünstiger ist als die streng periodische Präventivstrategie, 2. den Existenz-beweis einer optimalen Altersgrenze, nach deren Erreichen beim Eintritt einer Erneuerungsgelegenheit die Anlage vorbeugend zu erneuern ist, sofern die Anlage eine monoton wachsende Ausfallrate aufweist, 3. die Herleitung der Bestimmungsgleichung für die Altersgrenze bei exponentiell-verteilten Abständen zwischen den Erneuerungsgelegenheiten, 4. einen Weg zur Bestimmung der optimalen Ahersgrenze, wenn die Erneuerungsgelegenheiten äquidistant sind und 5. ein Verfahren zur approximativen Bestimmung der optimalen Altersgrenze.

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Summary This paper examines a variant of the most commonly used preventative replacement policies. The improvement of these policies is brought about by the simple expedient of replacing plant after a failure, but not always replacing it when a replacement opportunity such as a breakdown in the supply of energy occurs. Such policies, where replacement is not obligatory at every opportunity, are called optional preventative policies. The best policy in this class is to replace plant at occurence of an opportunity if its age has reached a control limit, otherwise to defer replacement.The author shows that there is an optional preventative policy which is cheaper than the strictly periodic preventative policy. For plant having an increasing failure rate he proves the existence of an optimal control limit. The equation determining that control limit is given for the case where the opportunities occur at random (exponentially distributed) or are entirely regular. Finally there is given a rule of thumb for determining a good replacement rule.

     

A novel methodological approach for δ18O analysis of sugars using gas chromatography-pyrolysis-isotope ratio mass spectrometry

Although the instrumental coupling of gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Py-IRMS) for compound-specific δ¹⁸O analysis has been commercially available for more than a decade, this method has been hardly applied so far. Here we present the first GC-Py-IRMS δ¹⁸O results for trimethylsilyl-derivatives of plant sap-relevant sugars and a polyalcohol (glucose, fructose, sucrose, raffinose and pinitol). Particularly, we focus on sucrose, which is assimilated in leaves and which is the most important transport sugar in plants and hence of utmost relevance in plant physiology and paleoclimate studies. Replication measurements of sucrose standards and concentration series indicate that the GC-Py-IRMS δ¹⁸O measurements are not stable over time and that they are amount (area) dependent. We, therefore, suggest running sample batch replication measurements in alternation with standard concentration series of reference material. This allows for carrying out (i) a drift correction, (ii) a calibration against reference material and (iii) an amount (area) correction. Tests with ¹⁸O-enriched water do not provide any evidence for oxygen isotope exchange reactions affecting sucrose and raffinose. We present the first application of GC-Py-IRMS δ¹⁸O analysis for sucrose from needle extract (soluble carbohydrate) samples. The obtained δ¹⁸O_{sucrose/ Vienna Standard Mean Ocean Water (VSMOW)} values are more positive and vary in a wider range (32.1–40.1 ‰) than the δ¹⁸O_{bulk/ VSMOW} values (24.6–27.2 ‰). Furthermore, they are shown to depend on the climate parameters maximum day temperature, relative air humidity and cloud cover. These findings suggest that δ¹⁸O_sucrose of the investigated needles very sensitively reflects the climatically controlled evaporative ¹⁸O enrichment of leaf water and thus highlights the great potential of GC-Py-IRMS δ¹⁸O_sucrose analysis for plant physiology and paleoclimate studies.     

Peano path derivatives

In this paper we introduce Peano path derivatives as a natural extension of the notion of path derivatives. We give a sufficient condition on a system of paths to ensure the corresponding Peano path derivative is Baire 1. As consequences, we obtain that unilateral approximate and unilateral -approximate Peano derivatives are Baire one.