Antimicrobial activity of transition metal acid MoO3 prevents microbial growth on material surfaces

Serious infectious complications of patients in healthcare settings are often transmitted by materials and devices colonised by microorganisms (nosocomial infections). Current strategies to generate material surfaces with an antimicrobial activity suffer from the consumption of the antimicrobial agent and emerging multidrug-resistant pathogens amongst others. Consequently, materials surfaces exhibiting a permanent antimicrobial activity without the risk of generating resistant microorganisms are desirable. This publication reports on the extraordinary efficient antimicrobial properties of transition metal acids such as molybdic acid (H₂MoO₄), which is based on molybdenum trioxide (MoO₃). The modification of various materials (e.g. polymers, metals) with MoO₃ particles or sol-gel derived coatings showed that the modified materials surfaces were practically free of microorganisms six hours after contamination with infectious agents. The antimicrobial activity is based on the formation of an acidic surface deteriorating cell growth and proliferation. The application of transition metal acids as antimicrobial surface agents is an innovative approach to prevent the dissemination of microorganisms in healthcare units and public environments.     

Carbon nanotube/graphene nanocomposite as efficient counter electrodes in dye-sensitized solar cells

We demonstrated the replacement of the Pt catalyst normally used in the counter electrode of a dye-sensitized solar cell (DSSC) by a nanocomposite of dry spun carbon multi-walled nanotube (MWNT) sheets with graphene flakes (Gr-F). The effectiveness of this counter electrode on the reduction of the triiodide in the iodide/triiodide redox (I(-)/I(3)(-)) redox reaction was studied in parallel with the use of the dry spun carbon MWNT sheets alone and graphene flakes used independent of each other. This nanocomposite deposited onto fluorinated tin-oxide-coated glass showed improved catalytic behavior and power conversion efficiency (7.55%) beyond the use of the MWNTs alone (6.62%) or graphene alone (4.65%) for the triiodide reduction reaction in DSSC. We also compare the use of the carbon MWNT/Gr-F composite counter electrode with a DSSC using the standard Pt counter electrode (8.8%). The details of increased performance of graphene/MWNT composite electrodes as studied are discussed in terms of increased catalytic activity permitted by sharp atomic edges that arise from the structure of graphene flakes or the defect sites in the carbon MWNT and increased electrical conductivity between the carbon MWNT bundles by the graphene flakes.     

Empfehlungen des Arbeitskreises 6.1 “Geotechnik der Deponiebauwerke” der Deutschen Gesellschaft für Geotechnik e.V. (DGGT)

Der Arbeitskreis Geotechnik der Deponiebauwerke hat in fünf Themengruppen bisher 76 Empfehlungen zur Planung, zum Bau und zur Qualitätsüberwachung von Abfalldeponien veröffentlicht. In diesem Bericht werden zwei überarbeitungen vorgestellt, eine grundsätzliche Neubarbeitung der E 2‐4, Oberflächenabdichtungssysteme und die an neuere Erfahrungen angepasste E 2‐33, Kapillarsperren in Oberflächenabdichtungen. Recommendations of the DGGT Committee “Geotechnics of Landfill Structures”. The Technical Committee ”Geotechnics of Landfill Structures” of the German Geotechnical Society published up to now 76 recommendations (GDA‐Geotechnical Landfill Recommendations) structured in 5 main issues. This paper introduces two new editions of currently important recommendations, the fundamentally reviewed E 2‐4, Capping Systems, and a new edition of E 2‐33, Capillary Barriers in Landfill Capping Systems.     

Standsicherheitsnachweis für Oberflächenabdichtungssysteme von Deponien

Verification of slope stability of surface sealing systems of landfill structures. According to national and european standards slope stability of capping systems should be verified with the concept of partial safety factors. The revised german recommendation E 2‐7 “Analysis of planar surface failure in lining systems” of the TC “Geotechnics of Landfill Structures” requires design approach 3, where actions are treated as geotechnical actions and partial safety factors are applied to the shear resistance of the soil in the potential slip surfaces. The tension force of a geogrid in case of reinforcement should be designed according to this approach. The paper describes the different failure modes of rupture and excessive deformations, the fundamentals of the verification procedure with partial safety factors, the limit state conditions in infinite slope analysis of stratified final capping systems as well as the design of reinforced structures. Hence, central point of the analysis is less the method of calculation as rather the determination of the effective shear parameters, which can be mobilised for a long period of time considering changing conditions and material ageing effects in the contact plane of the system.     

A comparative study of quality and safety of Atlantic cod (Gadus morhua) fillets during cold storage,as affected by different thawing methods of pre‐rigor frozen headed and gutted fish

BACKGROUND

The catch of marine whitefish is typically seasonal, whereas the land‐based processing industry has a need for all‐year stable supply of raw materials. This challenge can be met by applying fish frozen at sea. When using frozen fish, the methods employed for thawing may influence the safety and quality of the final product. This study aimed to investigate the applicability of novel thawing strategies in order to provide an all‐year supply of high‐quality and safe cod products.

RESULTS

Comparative investigations of quality and safety factors after thawing in water, with and without air circulation, and contact thawing were performed. The parameters included water‐holding capacity, thawing loss, drip loss, cooking yield, sensory evaluation and microbiological analyses (including total volatile bases nitrogen). Water thawing with air circulation provided faster thawing than water thawing without air circulation and contact thawing. For all three methods, the quality of the thawed fish was acceptable and the shelf life of the fillets during chilled storage was between 10 and 14 days post‐filleting.

CONCLUSION

The results show that controlled freezing of cod, followed by appropriate thawing, may provide the processing industry with an all‐year delivery of raw materials, without compromising quality and safety of the final product. © 2017 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.     

Synthesis of Cholesterol‐Substituted Glycopeptides for Tailor‐Made Glycocalyxification of Artificial Membrane Systems

Synthetic minimal membrane systems are extremely useful for better understanding of complex cellular structures and cell surface processes. We have developed a facile method for synthesis of cholesterylated peptides, each bearing a carbohydrate moiety and a fluorescent tag. The position of the cholesterol moiety on the peptide can be controlled by using a new Fmoc‐protected cholesterol‐triazole‐lysine group, which we constructed by means of solid‐phase peptide synthesis. We succeeded in integrating the glyco modules into giant unilamellar vesicles by electroformation or infusion in buffer solution. The glyco‐decorated liposomes were recognized by a lectin and had unique topological membrane features. In conclusion, this work is a proof of principle for the functionalization of artificial membranes with a primitive synthetic glycocalyx useful for studying carbohydrate–protein interactions on a simplified cell‐like membrane surface.     

Corrigenda

Supersaturated designs and associated analysis methods have been proposed by several authors to identify active factors in situations in which only a very limited number of experimental runs is available. We use simulation to evaluate the abilities of the existing methods to achieve model identification–related objectives. The results motivate a new class of supersaturated designs, derived from simulation optimization, that maximize the probability that stepwise regression will identify the important main effects. Because the proposed designs depend on specific assumptions, we also investigate the sensitivity of the performances of the alternative supersaturated designs to these assumptions.     

Models for Rod and Bar Rolling Mills with 2‑roll, 3‑roll,and 4‑roll Stands

For the quality of rolled products, a perfect surface quality and tight, close tolerances apart from defined mechanical properties are essential. One key condition is a perfect pass design in the rolling mill. The paper deals with the models for a pass design calculation as well as a calculation of roll force and power demands for the rolling mill. On modern bar and rod mill, different types of mill stands are used, with 2?roll, 3?roll, and 4?roll stands. For each of these stand types, a special model system is used for the calculation. Heat balance and temperature control by water cooling are the basis for thermomechanical rolling to achieve the desired mechanical properties of the material. Free size rolling and the compensation of the numerous influencing parameters on the product dimensions must be incorporated in a pass design.