Evaluation of Casimir Energies Through Spectral Functions

We consider applications of elliptic differential operators and their associated spectral functions in quantum field theory problems. The role of zeta functions and traces of heat kernels in the regularization of Casimir energies is emphasized, and the renormalization procedure is discussed with simple examples.     

Resolution of an iridoid synthon, gastrolactol, by means of dynamic acetylation and lipase-catalyzed alcoholysis

A short synthetic route to asymmetric iridoids was developed. The three key steps were an intramolecular [4 + 2] cycloaddition reaction of an enamine derivative of 8-oxocitral (2), a dynamic acetylation, and an enzymatic resolution of the gastrolactyl acetates 5a and 5b, iridoids with three stereocenters. Some regio- and stereoselective heterogeneous catalytic hydrogenations of double bonds in iridoid aglucones were discussed.     

Pore formation in fluctuating membranes

We study the nucleation of a single pore in a fluctuating lipid membrane, specifically taking into account the membrane fluctuations, as well as the shape fluctuations of the pore. For large enough pores, the nucleation free energy is well-described by shifts in the effective membrane surface tension and the pore line tension. Using our framework, we derive the stability criteria for the various pore formation regimes. In addition to the well-known large-tension regime from the classical nucleation theory of pores, we also find a low-tension regime in which the effective line and surface tensions can change sign from their bare values. The latter scenario takes place at sufficiently high temperatures, where the opening of a stable pore of finite size is entropically favorable.     

Synthesis and Reactivity of Mevinolin-Like Lactone Precursors

The synthesis of mevinolin-like lactone precursors and the evaluation of their ability in the N-alkylation of N-potassium-phthalimide are reported.     

Ruthenium-Catalyzed Hydrogenative Degradation of End-of-Life Poly(lactide) to Produce 1,2-Propanediol as Platform Chemical

The chemical recycling of end-of-life polymers can add some value to a future circular economy. In this regard, the hydrogenative degradation of end-of-life PLA was investigated to produce 1,2-propanediol as product, which is a useful building block in polymer chemistry. In more detail, the commercially available Ru-MACHO-BH complex was applied as catalyst to degrade end-of-life PLA efficiently to 1,2-propanediol under mild conditions. After investigations of the reaction conditions a set of end-of-life PLA goods were subjected to degradation.     

Approximating functions in hydrology of unsaturated soils—II

Summary Analytical expressions of conductivity and diffusivity have been obtained for an unsaturated sandy soil in the whole range of admissible values of volumetric water content. Besides fitting experimental values they satisfy a set of relations which guarantee that unphysical situations cannot be reached. The matric potential has been obtained by the numerical integration of a known relation which connects conductivity, diffusivity and matric potential.

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Riassunto Per un suolo sabbioso non saturo sono state ottenute delle espressioni analitiche della conducibilità idraulica e della diffusività per tutto l'intervallo di valori che il contenuto di acqua può assumere. Oltre ad approssimare i valori sperimentali, queste espressioni soddisfano alle condizioni imposte per garantire che non vengano raggiunte situazioni non fisiche. Il potenziale di matrice è stato ottenuto dalla integrazione numerica di una nota espressione analitica che lega tra loro conducibilità, diffusività e potenziale di matrice.

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Резюме Получаются аналитические выражения для проводимости и температуропроводности для ненасьщенных песчаных почв во всей области допустимых значений обьемных концентраций воды. Эти выражения аппроксимируют экспериментальные данные, а также удовлетворяют системе соотношений, которые гарантируют, что нефизические ситуации не могут возникать. Получается матричный потенциал с помощью численного интегрирования известного соотношения, которое связывает проводимость, температуропроводность и матричный потенциал.