An Interactive Stock Control System with a Strategic Management Role

This note describes the design, implementation and consequences of a stock control system employing interactive mini computers for a number of builders and plumbers merchants.The system enables the quantification of the strategic decisions of the company, for example the consequences of changing the total investment in stock, or the overall service level. The selected strategy determines the calculations used for the interactive buying routines, which consider items in groups. Other aspects and the results of the implementation are described together with the necessary theory and routines employed.     

A Comparison of Two Stock Control Models

Two methods of computing re-order levels are compared under an assumed state of nature. The results indicate that the difference, measured in terms of the expected lost sales is significant.     

Lanthanide-induced shifts in proton NMR spectra of cyclohexanones

The lanthanide-induced shifts (LIS) of the lanthanide shift reagent (LSR) Eu(FOD)₃ are reported for a large number of cyclohexanones, especially those which are highly substituted. The following compounds were synthesized and characterized: 3-(aryl)-3,5,5-trimethylcyclohexanones, in which aryl = 1-naphthyl, phenyl, o-anisyl, m-anisyl, p-anisyl and p-chlorophenyl. Some analogous compounds were also studied: 3,5,5-trimethylcyclohexanone, 4-tert-butyl-cyclohexanone, 3,3,5,5-tetramethylcyclohexanone 3-(1-naphthyl)5,5-dimethylcyclohexanone and para-tert-butyl-anisole. A method for the regression analysis of the concentration dependence of the LIS of these substrates is developed and reported, and used to derive the limiting incremental LIS (Δ₂) for the LS₂ complex and to evaluate the proton chemical shifts (δ₀) in the absence of LSR. An ‘incremental dilution’ technique was found to be most appropriate to insure constant substrate concentrations, needed to extract both Δ₂ and δ₀. The conformations of the 3-(aryl)-type systems and analogous compounds were studied via LIS and found to conform to:—(i) an axially disposed aryl substituent in the 3,3,5,5-tetra-substituted cyclohexanones and (ii) a flattened chair form of the cyclohexanone ring with distortions in this chair form being an increase in the syn-diaxial (C-3, C-5) substituent distance (C-3 and C-5 substituents still eclipsed). The LIS were fully compatible with these structural assumptions.     

Relationships between Service Level Measures for Inventory Systems

The service level provided by an inventory system can be measured in various ways. If different measures are used at a number of stock-holding depots, difficulties may arise in comparing performance or assessing the impact of depot centralization or decentralization. If the same measures are used at all depots but the inventory system changes from being based on one measure to another, similar problems arise. In this paper, relationships between six of the most frequently used service measures are presented, enabling each to be converted to a common measure. Data requirements for using the relationships are considered and, where appropriate, alternative relationships are presented which depend on data which may be more readily available in practice.     

Autoradiography using storage phosphor technology

We describe the application of photostimulable storage phosphor imaging plates to autoradiography of samples labeled with 32P, 14C and 35S. Imaging plates can detect a 32P-labeled sample at an exposure level of 1 disintegration/mm2, and 14C and 35S at 25 disintegrations/mm2. Compared to X-ray film, imaging plates offer increased sensitivity of 15- to 250-fold for 32P and 20- to 100-fold for 14C and 35S. Resolution is in the 0.3 mm range and is therefore suitable for any gel or blot application.     

An upwind scheme for the three-dimensional boundary layer equations

The development of a calculation method to solve the compressible, three-dimensional, turbulent boundary layer equations is described. An implicit finite difference solution procedure is adopted involving local upwinding of convective transport terms. A consistent approach to discretization and linearization is taken by casting all equations in a similar form. The implementation of algebraic, one-equation and two-equation turbulence models is described. An initial validation of the method is made by comparing prediction with measurements in two quasi-three-dimensional boundary layer flows. Some of the more obvious deficiencies in current turbulence-modelling standards for three-dimensional flows are discussed.     

The Brønsted acid-catalyzed direct aza-Darzens synthesis of N-alkyl cis-aziridines

A mild protocol for the synthesis of cis-aziridines is described that employs a catalytic amount of Br?nsted acid. Despite the potential for diazo compound decomposition via alkylation or homocoupling upon exposure to a proton source, these pathways are slow relative to [2 + 1] annulation in the presence of a Schiff base, leading to aziridine product. The process uses no metals or reagents that must be removed chromatographically, exhibits rapid turnover rates, and produces only atomic nitrogen as a coproduct. High levels of relative stereocontrol are also possible when forming the Schiff base from a chiral nonracemic aldehyde.     

Dynamics of magnetic defects in heavy fermion LiV2O4 from stretched exponential 7Li NMR relaxation

7Li NMR measurements on LiV2O4 from 0.5 to 4.2 K are reported. A small concentration of magnetic defects within the structure drastically changes the nuclear magnetization relaxation versus time from a pure exponential as in pure LiV2O4 to a stretched exponential, indicating glassy behavior of the magnetic defects. The stretched exponential function is described as arising from a distribution of 7Li nuclear spin-lattice relaxation rates and we present a model for the distribution in terms of the dynamics of the magnetic defects. Our results explain the origin of recent puzzling 7Li NMR literature data on LiV2O4 and our model is likely applicable to other glassy systems.     

The first synthetic studies on pestalotiopsin A. A stereocontrolled approach to the functionalised bicyclic core

Pestalotiopsin A is a structurally unique, caryophyllene-type sesquiterpene which has shown immunosuppressive activity and cytotoxicity in preliminary assays. A stereocontrolled approach to the functionalised 2-oxabicyclo[3.2.0]-heptane core of pestalotiopsin A is described. This constitutes the first synthetic studies on pestalotiopsin A. Our approach includes a samarium(II)-mediated 4-exo-trig cyclisation and a trans-lactonisation process triggered by the addition of alkylytterbium reagents to a cyclobutanone intermediate. Further manipulation provides access to advanced intermediates which are excellent precursors for the future construction of the final ring of the target.