Hydroisomerization of Renewable and Fossil n-Alkanes over Bifunctional Dealuminated ZSM-5 Catalysts

The hydroisomerization of two long-chain n-alkane mixtures was investigated over bifunctional Pt/H-ZSM-5 catalysts before and after dealumination of preshaped zeolite/binder pellets. The hydroisomerization over the dealuminated catalysts leads to more isomers and less cracking products. Consequently, higher ratios of multi- to mono-branched isomerization products are formed as expected for large- rather than medium-pore zeolites. This indicates a higher availability of space in the vicinity of the active sites and provides an attractive route to make medium-pore zeolites suitable for upgrading higher boiling hydrocarbon feeds.     

Charakterisierung und Störstoffanalyse von rückgewonnenen Stoffströmen aus Wärmedämmverbundsystemen

Due to the growing energy requirements, the proportion of external thermal insulation composite systems (ETICS) installed has increased significantly during the past 50 years. Due to the longevity of these systems, ETICS waste is currently accumulating. Owing to the complex construction as well as a multitude of differently installed materials and substances of the past generations, there are many uncertainties and problems with the clean and low-pollutant processing of such systems. In the frame of this work, the ETICS were processed and sorted before being screened for ingredients or pollutants as well as for the purity of the recovered material fractions.     

A High-Throughput Screening System Based on Fluorescence-Activated Cell Sorting for the Directed Evolution of Chitinase A

Chitinases catalyze the degradation of chitin, a polymer of N-acetylglucosamine found in crustacean shells, insect cuticles, and fungal cell walls. There is great interest in the development of improved chitinases to address the environmental burden of chitin waste from the food processing industry as well as the potential medical, agricultural, and industrial uses of partially deacetylated chitin (chitosan) and its products (chito-oligosaccharides). The depolymerization of chitin can be achieved using chemical and physical treatments, but an enzymatic process would be more environmentally friendly and more sustainable. However, chitinases are slow-acting enzymes, limiting their biotechnological exploitation, although this can be overcome by molecular evolution approaches to enhance the features required for specific applications. The two main goals of this study were the development of a high-throughput screening system for chitinase activity (which could be extrapolated to other hydrolytic enzymes), and the deployment of this new method to select improved chitinase variants. We therefore cloned and expressed the Bacillus licheniformis DSM8785 chitinase A (chiA) gene in Escherichia coli BL21 (DE3) cells and generated a mutant library by error-prone PCR. We then developed a screening method based on fluorescence-activated cell sorting (FACS) using the model substrate 4-methylumbelliferyl β-d-N,N′,N″-triacetyl chitotrioside to identify improved enzymes. We prevented cross-talk between emulsion compartments caused by the hydrophobicity of 4-methylumbelliferone, the fluorescent product of the enzymatic reaction, by incorporating cyclodextrins into the aqueous phases. We also addressed the toxicity of long-term chiA expression in E. coli by limiting the reaction time. We identified 12 mutants containing 2–8 mutations per gene resulting in up to twofold higher activity than wild-type ChiA.     

Prediction of Glass Forming Ability Through High Throughput Calculation

In this work, high throughput calculation (HTC) is used to identify composition regions with good glass forming ability (GFA) in the Al-Cu-Zr, Cu-Ni-Zr, Cu-Ti-Zr, Cu-Ni-Ti-Zr, Al-Cu-Ni-Ti-Zr, Mg-Ca-Cu, and Mg-Ca-Ni systems. The predicted composition regions agree well with those observed by experiments in the ternary systems, while less satisfactory agreement is found in the Cu-Ni-Ti-Zr quaternary and the Al-Cu-Ni-Ti-Zr quinary systems. The possible causes that lead to the deviation in the higher order systems are discussed. The major advantage of the HTC method used in this study is that it is simple and can be easily applied to multicomponent systems. The color maps of liquidus temperature and solidification range obtained by HTC provide a valuable guidance to the experimentalists, thus they can focus on the composition regions with high potential of forming bulk metallic glasses, avoid unnecessary trial-and-error test and save time and cost. This approach can also be combined with other criteria to filter compositions with better GFA.     

Dimensional Effects on Densities of States and Interactions in Nanostructures

We consider electrons in the presence of interfaces with different effective electron mass, and electromagnetic fields in the presence of a high-permittivity interface in bulk material. The equations of motion for these dimensionally hybrid systems yield analytic expressions for Green’s functions and electromagnetic potentials that interpolate between the two-dimensional logarithmic potential at short distance, and the three-dimensional r ⁻¹ potential at large distance. This also yields results for electron densities of states which interpolate between the well-known two-dimensional and three-dimensional formulas. The transition length scales for interfaces of thickness L are found to be of order Lm/2m _* for an interface in which electrons move with effective mass m _*, and Le_*/2eLepsilon_ast/2epsilon for a dielectric thin film with permittivity e_*epsilon_ast in a bulk of permittivity eepsilon. We can easily test the merits of the formalism by comparing the calculated electromagnetic potential with the infinite series solutions from image charges. This confirms that the dimensionally hybrid models are excellent approximations for distances r ≳ L/2.     

Ultrafine comminution of dental glass in a stirred media mill

A systematic study on the comminution of amorphous glass particles with complex composition (seven constituents) to produce nanoparticles has been performed in a high-energy stirred media mill. The influence of solids loading, dispersion stabilisation via pH and addition of dispersants on particle size was investigated in aqueous suspensions. Further, the effect of using 2-propanol and benzyl alcohol as dispersion media on the particle size and morphology is presented and compared to the aqueous system. The specific surface area of the product powder was analysed by the BET method, the secondary particle size was determined by static light scattering and the morphology was investigated by SEM and TEM. Dispersion viscosity and stability was measured using rotational viscosimetry and zeta-potential measurements, respectively. The results show that the solids loading plays a central role in the comminution efficiency, where lower loadings lead to finer particles after a given milling time. Stabilisation of the aqueous powder dispersion by adjusting the pH or by adding a dispersant did not result in an enhanced milling efficiency in terms of fast reduction of the particle size. The smallest glass nanoparticles with a primary particle size were achieved by a two-step comminution process. The particles were irregularly shaped when milled in water, however, when processed in 2-propanol and benzyl alcohol, they had a plate-like geometry.     

Molecular Network Approach Reveals Rictor as a Central Target of Cardiac ProtectomiRs

Cardioprotective medications are still unmet clinical needs. We have previously identified several cardioprotective microRNAs (termed ProtectomiRs), the mRNA targets of which may reveal new drug targets for cardioprotection. Here we aimed to identify key molecular targets of ProtectomiRs and confirm their association with cardioprotection in a translational pig model of acute myocardial infarction (AMI). By using a network theoretical approach, we identified 882 potential target genes of 18 previously identified protectomiRs. The Rictor gene was the most central and it was ranked first in the protectomiR-target mRNA molecular network with the highest node degree of 5. Therefore, Rictor and its targeting microRNAs were further validated in heart samples obtained from a translational pig model of AMI and cardioprotection induced by pre- or postconditioning. Three out of five Rictor-targeting pig homologue of rat ProtectomiRs showed significant upregulation in postconditioned but not in preconditioned pig hearts. Rictor was downregulated at the mRNA and protein level in ischemic postconditioning but not in ischemic preconditioning. This is the first demonstration that Rictor is the central molecular target of ProtectomiRs and that decreased Rictor expression may regulate ischemic postconditioning-, but not preconditioning-induced acute cardioprotection. We conclude that Rictor is a potential novel drug target for acute cardioprotection.     

Sustainability of biofuels in Latin America: Risks and opportunities

Several Latin American countries are setting up biofuel programmes to establish alternative markets for agricultural commodities. This is mainly triggered by the current success of Brazilian bioethanol production for the domestic market and for export. Furthermore, the global biofuel market is expected to increase due to ambitious biofuel programmes in the EU and in the USA. Colombia, Venezuela, Costa Rica and Guatemala are focusing on bioethanol production from sugarcane whereas biofuel production in Argentina is based on soy biodiesel. Recent developments of the biofuel sector take place extremely rapid especially in Argentina, which became one of the five largest biodiesel producers in the world in 2008. Till date no specific biofuel sustainability certification systems have been implemented in Latin American, as well as on global level. This fact and the predominant use of food crops for biofuel production raise concerns about the sustainability of biofuel production related to environmental and social aspects. This paper provides an overview of the hotspots of conflicts in biofuel production in Latin America. It investigates presently available sustainability tools and initiatives to ensure sustainable biofuel production in Latin America. Finally, it provides an outlook on how to integrate sustainability in the Latin American biofuel sector.