X-ray diffraction and melting-point studies on some long-chain sulfur-containing acids

Summary X-ray diffraction powder data and melting points have been determined on three series of crystalline long-chain sulfur compounds, namely 11-(n-alkylsulfonyl)-undecanoic acids; 11-(n-alkylsulfinyl) undecanoic acids; and 11-(n-alkylthio) undecanoic acids; where R is a selected alkyl group from methyl through undecyl. In the sulfone series the long spacings increase regularly with the increase in the number of carbon atoms in R. In contrast to unsubstituted longchain fatty acids the odd and even members fall on the same line in the plot of long spacings against carbon atoms in R. As expected, a nonalternation in melting point is observed. In both the sulfoxide and sulfide series two nonparallel straight lines are obtained, one for the even-membered and one for the odd-membered compounds, in the plot of long spacings against carbon atoms in R. As expected, the melting points of the sulfoxides and sulfides show an alternation. Polymorphism is more evident and complicates the interpretations most in the sulfide series and least in the sulfone series. all three series of compounds crystallized as tilted dimers. This is paper IV in the series on “Organic Sulfur Derivatives.” Paper III is by H. Susi, N. H. Koenig, W. E. Parker, and Daniel Swern, Anal. Chem.,30, 443 (1958). Eastern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

The Effect of Selection Errors in Cost Estimation1

This article quantifies the error induced by selecting the most desirable alternative from several under consideration. This selection effect was demonstrated under two different definitions of error. Model A error was associated with the difference in actual and estimated outcomes of an alternative. Model B error was associated with regret for not selecting the best alternative. The model A error was shown to be at a maximum when the proposed alternatives were nearly equal. This error also decreased as the coefficient of separation increased, and therefore shows that the effect of selection cannot be used to explain estimation deviations in many situations.     

X-ray diffraction powder data of some thiol esters of long chain fatty acids

Summary X-ray diffraction powder data were obtained for 14 thiol esters of long chain fatty acids including benzyl, β-naphthyl,n-amyl, andn-hexyl thiol myristates; thiol palmitates; thiol stearates; and in some cases thiol laurates. All the individual compounds can be readily distinguished and identified by the diffraction data. Long spacings increase regularly with increase in hydrocarbon chain length. The benzyl and β-naphthyl thiol esters crystallize in tilted bimolecular layers while then-amyl andn-hexyl thiol derivatives crystallize in tilted monomolecular layers. One of the laboratories of the Eastern Utilization Research Branch, Agricultural Research Service, U. S. Department of Agriculture.     

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Fischer-Tropsch-Synthese. Neuere Untersuchungen und Entwicklungen

Fischer-Tropsch synthesis – Recent studies and Developments . This article surveys some results of recent research and new lines of development in Fischer-Tropsch synthesis. Most interest is focussed on variants synthesis showing high selectivity of C₂-C₄ alkenes or C₅-C₂₀ 1-alkenes or Diesel oil. In the last decade catalysts of improved alkene selectivity have been developed. Also the dependence of selectivity on process parameters such as pressure of hydrogen and carbon monoxide and temperature has been investigated in order to find appropriate conditions of operation for a synthesis of high selectivity. Some preliminary process designs are discussed.     

Synthesis and characterization of polyalkylmethacrylate macromonomers

Summary The synthesis of polyalkylmethacrylate macromonomers has been performed anionically by direct deactivation of the carbanionic sites with p-vinyl-or p-isopropenylbenzyl bromide. The characterization of the samples proved that the yields are close to quantitative, and that no side reactions are involved. The method also applies to hydroxyethylmethacrylate and to glycerylmethacrylate, provided the monomers are made aprotic by reversible silylation or acetalization.The authors want to express their deep appreciation to MM. J.Ph. Lamps F. Isel and to Mrs. S. Graff for their technical assistance.     

Metal-chelating amino acids as building blocks for synthetic receptors sensing metal ions and histidine-tagged proteins

Protein structure and function rely on a still not fully understood interplay of energetic and entropic constraints defined by the permutation of the twenty genetically encoded amino acids. Many attempts have been undertaken to design peptide-peptide interaction pairs and synthetic receptors de novo by using this limited number of building blocks. We describe a rational approach to creating a building block based on a tailored metal-chelating amino acid. Nepsilon,Nepsilon-bis(carboxymethyl)-L-lysine can be flexibly introduced into peptides by 9-fluorenylmethoxycarbonyl solid-phase chemistry. The corresponding metal-chelating peptides act as metal sensors and synthetic receptors for histidine-tagged proteins. These biochemical tweezers will open new ways to control protein-protein interactions, to design peptide-based interaction pairs, or to generate switchable protein function.     

Identification of new homoterpene esters from Dufour's gland of the ponerine ant Gnamptogenys striatula

Extracts of Dufour's gland of the ponerine ant, Gnamptogenys striatula, were analyzed by using the combination of gas chromatography and mass spectrometry. Series of esters of the new homoterpenoids (2E,6)-3,4,7-trimethyl-2,6-octadiene-1-ol (4-methylgeraniol) and (2E,6)-3,4,7-trimethyl-2, 6-nonadiene-1-ol (bishomogeraniol) with unbranched medium-chain fatty acids were identified. Transformation of the chiral natural products into 1,4-di(trifluoroacetoxy)-3-methylpentane and comparison of its gas chromatographic retention time on a modified cyclodextrin phase with that of synthetic optically active reference samples proved the stereogenic center to keep (S)-configuration. (2E,4S,6)-3,4,7-Trimethyl-2,6-octadien-1-yl decanoate and the corresponding dodecanoate are the main volatiles in the extracts.     

Strategy Alignment of Mobile Solutions in Customer-Oriented Processes

In this paper we analyze how companies define their strategy, especially how they interact with and appear to the customer. Based on a framework of five goals in customer oriented strategy, we classify seven cases. Analyzing the strategic premises and the processes chosen to be supported by mobile solutions, we show interdependencies between the strategic premises and the selected processes, resulting in typical properties which qualify processes for mobilization.