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411.
Patrik Blumenthal Marc C. Steger Daniel Einfalt Jrg Rieke-Zapp Andrs Quintanilla Bellucci Katharina Sommerfeld Steffen Schwarz Dirk W. Lachenmeier 《Molecules (Basel, Switzerland)》2021,26(9)
Methanol is a natural ingredient with major occurrence in fruit spirits, such as apple, pear, plum or cherry spirits, but also in spirits made from coffee pulp. The compound is formed during fermentation and the following mash storage by enzymatic hydrolysis of naturally present pectins. Methanol is toxic above certain threshold levels and legal limits have been set in most jurisdictions. Therefore, the methanol content needs to be mitigated and its level must be controlled. This article will review the several factors that influence the methanol content including the pH value of the mash, the addition of various yeast and enzyme preparations, fermentation temperature, mash storage, and most importantly the raw material quality and hygiene. From all these mitigation possibilities, lowering the pH value and the use of cultured yeasts when mashing fruit substances is already common as best practice today. Also a controlled yeast fermentation at acidic pH facilitates not only reduced methanol formation, but ultimately also leads to quality benefits of the distillate. Special care has to be observed in the case of spirits made from coffee by-products which are prone to spoilage with very high methanol contents reported in past studies. 相似文献
412.
We study limits of convergent sequences of string graphs, that is graphs with an intersection representation consisting of curves in the plane. We use these results to study the limiting behavior of a sequence of random string graphs. We also prove similar results for several related graph classes. 相似文献
413.
Quantitative analysis of trace levels of surface contamination by X‐ray photoelectron spectroscopy. Part II: Systematic uncertainties and absolute quantification
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Nadir S. Faradzhev Shannon B. Hill Cedric J. Powell 《Surface and interface analysis : SIA》2017,49(12):1214-1224
We discuss analyses of trace levels of surface contamination using X‐ray photoelectron spectroscopy (XPS). The problem of quantifying common sources of statistical and systematic uncertainties for these measurements is formulated in terms of the needs of extreme ultraviolet lithography, but the results and conclusions are applicable to a broad range of XPS applications. We quantify the systematic uncertainties introduced by particular cases of overlapping peaks on different substrate structures by simulating measured spectra with the National Institute of Standards and Technology Database for the Simulation of Electron Spectra for Surface Analysis (SESSA). One example demonstrates that the relative atomic concentrations of trace elements such as S, P, and halogens on a Ru surface could be dramatically overestimated if the fitting of the overlapping Ru 3d and C 1s peaks excludes the contribution from carbon. We also show how spectra generated by SESSA can be compared with measured spectra to determine absolute amounts of surface impurities on layered samples of the type used for extreme ultraviolet lithography. We provide estimates of the total uncertainty for such measurements by considering the systematic limitations of SESSA and the statistical uncertainties of the measurements. The same procedure can be employed for other multilayered materials. Finally, we describe two approaches for converting XPS detection limits for an elemental impurity in an elemental matrix to the corresponding detection limits for the impurity as a thin film on the surface of the matrix material. 相似文献
414.
This paper examines all the possible types of thermomechanical constraints in finite-deformational elasticity. By a thermomechanical constraint we mean a functional relationship between a mechanical variable, either the deformation gradient or the stress, and a thermal variable, temperature, entropy or one of the energy potentials; internal energy, Helmholtz free energy, Gibbs free energy or enthalpy. It is shown that for the temperature-deformation, entropy-stress, enthalpy-deformation, and Helmholtz free energy-stress constraints equilibrium states are unstable, in the sense that certain perturbations of the equilibrium state grow exponentially. By considering the constrained materials as constitutive limits of unconstrained materials, it is shown that the instability is associated with the violation of the Legendre–Hadamard condition on the internal energy. The entropy-deformation, temperature-stress, internal energy-stress, and Gibbs free energy-deformation constraints do not exhibit this instability. It is proposed that stability of the rest state (or equivalently convexity of internal energy) is a necessary requirement for a model to be physically valid, and hence entropy-deformation, temperature-stress, internal energy-stress, and Gibbs free energy-deformation constraints are physical, whereas temperature-deformation constraints (including the customary notion of thermal expansion that density is a function of temperature only), entropy-stress constraints, enthalpy-deformation constraints, and Helmholtz free energy-stress constraints are not. 相似文献
415.
416.
A method of localization is proposed to lower the high order of equations in FEM calculation for the stability of a complex
thin-walled structure. The localized analysis enables us to obtain both the upper and lower limits for the bifurcating point
in a whole linear-elastic structural system, as well as an approximate solution to asymptotic post-buckling problem. Some
numerical examples are included.
Project supported by National Natural Science Foundation of China 相似文献
417.
A ring of I cells rotates past I queues, carrying customers from their origins to their destinations. The system is modelled as a Markov chain, and the exact ergodicity conditions are given. They are shown to depend on the precise travel lengths distributions, that is, not only on their means. Ergodicity is proven through the stability analysis of the associated fluid limits. The arrivals distributions, which in the ergodicity conditions appear only through their means, are more subtly involved in the fluid limits behaviour, in that they determine the probabilities of random bifurcations that occur infinitely often in a simple system of I=2 queues. 相似文献
418.
Yao Weixing 《Acta Mechanica Solida Sinica》1996,9(4):337-349
419.
420.
Existence of a phase separation is proved for a classical lattice gas with finite-range pair potential under the action of a weak gravitational field. 相似文献