Ueber die Einwirkung einiger Agentien auf in der Natur vorkommende Carbonate

Ohne Zusammenfassung     

A comparative study of modeling and solution approaches for the coordinated lot-size problem with dynamic demand

In the coordinated lot-size problem, a major setup cost is incurred when at least one member of a product family is produced and a minor setup cost for each different item produced. This research consolidates the various modeling and algorithmic approaches reported in the literature for the coordinated replenishment problem with deterministic dynamic demand. For the two most effective approaches, we conducted extensive computational experiments investigating the quality of the lower bound associated with the model’s linear programming relaxation and the computational efficiency of the algorithmic approaches when used to find heuristic and optimal solutions. Our findings indicate the superiority of the plant location type problem formulation over the traditional approach that views the problem as multiple single-item Wagner and Whitin problems that are coupled by major setup costs. Broader implications of the research suggest that other classes of deterministic dynamic demand lot-size problems may also be more effectively modeled and solved by adapting plant location type models and algorithms.     

Solving 0-1 Minimax Problems

It has been shown that it is possible to solve a minimax 0-1 programming problem by transforming the objective function coefficients and solving a minisum problem. This result is very useful for solving a ‘hard’ minimax problem when there exists a ‘relatively easy’ algorithm to solve the minisum problem. We discuss such problems and present a new transformation.     

Novel mixed-valent Co(II)₂Co(III)₄Ln(III)₄ aggregates with ligands derived from tris-(hydroxymethyl)aminomethane (Tris)

Isostructural Co(II)?Co(III)?Ln(III)? (Ln = Y (1), Gd (2) and Dy (3)) coordination clusters formed using the ligand Tris are the first examples of 3d-4f complexes involving this ligand and show weak ferromagnetic coupling between the Co(II) ions and slow relaxation (SMM) behaviour for 3.     

The equivalence of bar recursion and open recursion

Several extensions of Gödel's system T$\mathsf{T}$ with new forms of recursion have been designed for the purpose of giving a computational interpretation to classical analysis. One can organise many of these extensions into two groups: those based on bar recursion, which include Spector's original bar recursion, modified bar recursion and the more recent products of selections functions, or those based on open recursion   which in particular include the symmetric Berardi–Bezem–Coquand (BBC) functional. We relate these two groups by showing that both open recursion and the BBC functional are primitive recursively equivalent to a variant of modified bar recursion. Our results, in combination with existing research, essentially complete the classification up to primitive recursive equivalence of those extensions of system T$\mathsf{T}$ used to give a direct computational interpretation to choice principles.     

Rapid quantification of TBP and TBP degradation product ratios by FTIR-ATR

Tri-n-butyl phosphate (TBP) is the key complexant within the plutonium and uranium reduction extraction process used to extract uranium and plutonium from used nuclear fuel. During reprocessing TBP degrades to dibutyl phosphate (DBP), butyl acid phosphate (MBP), butanol, and phosphoric acid over time. A method for rapidly monitoring TBP degradation is needed for the support of nuclear forensics. Therefore, a Fourier transform infrared spectrometry-attenuated total reflectance (FTIR-ATR) technique was developed to determine approximate peak intensity ratios of TBP and its degradation products. The technique was developed by combining variable concentrations of TBP, DBP, and MBP to simulate TBP degradation. This method is achieved by analyzing selected peak positions and peak intensity ratios of TBP and DBP at different stages of degradation. The developed technique was tested on TBP samples degraded with nitric acid. In mock degradation samples, the 1,235 cm^?1 peak position shifts to 1,220 cm^?1 as the concentration of TBP decreases and DBP increases. Peak intensity ratios of TBP positions at 1,279 and 1,020 cm^?1 relative to DBP positions at 909 and 1,003 cm^?1 demonstrate an increasing trend as the concentration of DBP increases. The same peak intensity ratios were used to analyze DBP relative to MBP whereas a decreasing trend is seen with increasing DBP concentrations. The technique developed from this study may be used as a tool to determine TBP degradation in nuclear reprocessing via a rapid FTIR-ATR measurement without gas chromatography analysis.     

Evaluating the accuracy of theoretical one‐bond 13C─13C scalar couplings and their ability to predict structure in a natural product

This study explores the feasibility of using a combination of experimental and theoretical 1‐bond ¹³C─¹³C scalar couplings (¹J_CC) to establish structure in organic compounds, including unknowns. Historically, ⁿJ_CC and ⁿJ_CH studies have emphasized 2 and 3‐bond couplings, yet ¹J_CC couplings exhibit significantly larger variations. Moreover, recent improvements in experimental measurement and data processing methods have made ¹J_CC data more available. Herein, an approach is evaluated in which a collection of theoretical structures is created from a partial nuclear magnetic resonance structural characterization. Computed ¹J_CC values are compared to experimental data to identify candidates giving the best agreement. This process requires knowledge of the error in theoretical methods, thus the B3LYP, B3PW91, and PBE0 functionals are evaluated by comparing to 27 experimental values from INADEQUATE. Respective errors of ±1.2, ±3.8, and ±2.3 Hz are observed. An initial test of this methodology involves the natural product 5‐methylmellein. In this case, only a single candidate matches experimental data with high statistical confidence. This analysis establishes the intramolecular hydrogen‐bonding arrangement, ring heteroatom identity, and conformation at one position. This approach is then extended to hydroheptelidic acid, a natural product not fully characterized in prior studies. The experimental/theoretical approach proposed herein identifies a single best‐fit structure from among 26 candidates and establishes, for the first time, 1 configuration and 3 conformations to complete the characterization. These results suggest that accurate and complete structural characterizations of many moderately sized organic structures (<800 Da) may be possible using only ¹J_CC data.     

Powergraph — a network-based approach to modelling and managing corporate strategic conflict and co-operation

Strategic relationships between companies are characterised by a combination of conflict and co-operation. Often the behaviour of partner/rival companies will appear arbitrary, almost irrational because of the necessary limitations on communication between the parties. Understanding, predicting and managing situations such as major project teamings or acquisition struggles is essential for the satisfactory governance of companies but existing conflict modelling has proven less than attractive to practitioners and their advisors. A network-based approach known as Powergraph is described in this study. It represents the corporate situation as a directed graph in which the nodes are the possible states of play. Connections between nodes are represented by logical expressions deriving from the capacities of the players individually or in coalition to bring about the transitions. By consideration of the ordinal preferences of the participants, trajectories of the situation can be described and these trajectories form the basis for management action and intelligence gathering. The method is illustrated by means of a real case study of three defence companies competing for two major contracts.