An efficient method for the calculation of chemical equilibrium composition in multicomponent gas mixtures

The determination of the composition of multi-component mixtures is the basis by which a number of technical and physical problems in the field of power and process engineering are modelled. In order to calculate chemical states of equilibrium in the gas phase, a calculation method will be presented which is founded on a minimization of the Gibbs enthalpy. This method is characterized by a high reliability in convergency, considerable independence of starting vectors and by a moderate requirement for programming. These characteristics are achieved by a transformation of variables which results in numerically more favourable solutions to the non-linear equation system. Calculated equilibrium compositions (including dissociation and ionisation) for a stochiometric mixture of hydrogen and oxygen in a temperature range of 300–12000 K and a pressure of 10⁵ Pa as well as the application of the method will be demonstrated.     

Mikrobielle Werkstoffzerstörung – Schadensfälle und Gegenmaßnahmen: Anwendung von Mikrobiziden. para-Chlor-meta-Kresol (PCMK) – Ein klassisches Mikrobizid mit Zukuntt

Microbial deterioration of materials – case histories and countermeasures: Application of microbicides. Para-chloro-meta-cresol (PCMC)

1 Preventol®CMK.

– A classic microbicide with a future     

Consideration of maldistribution in heat exchangers using the hyperbolic dispersion model

Axial temperature profiles in a shell and tube heat exchanger are numerically calculated for given maldistributions on the tube side. For comparison the same maldistributions are handled with the parabolic and hyperbolic dispersion model with fitted values for the axial dispersion coefficient and third sound wave velocity. The analytical results clearly demonstrate that the hyperbolic model is better suited to describe the steady state axial temperature profiles.     

Leaf-Miners Co-opt Microorganisms to Enhance their Nutritional Environment

Organisms make the best of their mother’s oviposition choices and utilize specific feeding options that meet energetic requirements and cope with environmental constraints. This is particularly true for leaf-miner insects that develop enclosed in the two epidermis layers of a single leaf for their entire larval life. Cytokinins (CKs) play a central role in plant physiology – including regulation of senescence and nutrient translocation – and, as such, can be the specific target of plant exploiters that manipulate plant primary metabolism. ‘Green-islands’ are striking examples of a CK-induced phenotype where green areas are induced by plant pathogens/insects in otherwise yellow senescent leaves. Here, we document how the leaf-miner caterpillar Phyllonorycter blancardella, working through an endosymbiotic bacteria, modifies phytohormonal profiles, not only on senescing (photosynthetically inactive) but also on normal (photosynthetically active) leaf tissues of its host plant (Malus domestica). This leaf physiological manipulation allows the insect to maintain sugar-rich green tissues and to create an enhanced nutritional microenvironment in an otherwise degenerating context. It also allows them to maintain a nutritional homeostasis even under distinct leaf environments. Our study also highlights that only larvae harboring bacterial symbionts contain significant amounts of CKs that are most likely not plant-derived. This suggests that insects are able to provide CKs to the plant through their symbiotic association, thus extending further the role of insect bacterial symbionts in plant-insect interactions.     

Upconversion in solar cells

The possibility to tune chemical and physical properties in nanosized materials has a strong impact on a variety of technologies, including photovoltaics. One of the prominent research areas of nanomaterials for photovoltaics involves spectral conversion. Modification of the spectrum requires down- and/or upconversion or downshifting of the spectrum, meaning that the energy of photons is modified to either lower (down) or higher (up) energy. Nanostructures such as quantum dots, luminescent dye molecules, and lanthanide-doped glasses are capable of absorbing photons at a certain wavelength and emitting photons at a different (shorter or longer) wavelength. We will discuss upconversion by lanthanide compounds in various host materials and will further demonstrate upconversion to work for thin-film silicon solar cells.     

Electrokinetic phosphorus recovery from packed beds of sewage sludge ash: yield and energy demand

The static lifetime of primary phosphate stocks is estimated as one century. Thus, the exploitation of secondary phosphorus sources becomes increasingly important. This study focussed on the feasibility of an electrokinetic phosphorus recovery from sewage sludge ash (P-content ~5 wt%). Packed bed experiments were conducted under varied electric conditions with and without acid pre-treatment and employing porous and ion exchange materials as electrode wells. Maximum values of phosphate concentration obtained in all experiments were around 2.5 g L⁻¹. Galvanostatic conditions were superior to potentiostatic conditions and acid pre-treatment is preferable over packed bed saturation with water. Ion-exchange membranes improved the product quality but increased the energy demand. Phosphorus recovery below 1% of the initial contents shows that the recovery setup must be improved in view of a marketable application.