Easy and Rapid Purification of Highly Active Nisin

Nisin is an antimicrobial peptide produced and secreted by several L. lactis strains and is specifically active against Gram-positive bacteria. In previous studies, nisin was purified via cation exchange chromatography at low pH employing a single-step elution using 1 M NaCl. Here, we describe an optimized purification protocol using a five-step NaCl elution to remove contaminants. The obtained nisin is devoid of impurities and shows high bactericidal activity against the nisin-sensitive L. lactis strain NZ9000. Purified nisin exhibits an IC50 of ~3 nM, which is a tenfold improvement as compared to nisin obtained via the one-step elution procedure

Phenylimino Indolinone:A Green-Light-Responsive T-Type Photoswitch Exhibiting Negative Photochromism

Imines are photoaddressable motifs useful in the development of new generations of molecular switches, but their operation with low-energy photons and control over isomer stability remain challenging. Based on a computational design, we developed phenylimino indolinone (PIO), a green-light-addressable T-type photoswitch showing negative photochromism. The isomerization behavior of this photoactuator of the iminothioindoxyl (ITI) class was studied using time-resolved spectroscopies on time scales from femtoseconds to the steady state and by quantum-chemical analyses. The understanding of the isomerization properties and substituent effects governing these photoswitches opens new avenues for the development of novel T-type visible-light-addressable photoactuators based on C=N bonds

Modularisation Strategies for Individualised Precast Construction—Conceptual Fundamentals and Research Directions

Modular precast construction is a methodological approach to reduce environmental impacts and increase productivity when building with concrete. Constructions are segmented into similar precast concrete elements, prefabricated with integrated quality control, and assembled just-in-sequence on site. Due to the automatised prefabrication, inaccuracies are minimised and the use of high-performance materials is enabled. As a result, the construction process is accelerated, and the modules can be designed to be lightweight and resource-efficient. This contribution presents the fundamentals of modular constructions made from precast concrete components. Then, to elaborate the requirements of a contemporary modular precast construction, the historic developments are described. Further, concepts and technical processes–comprehensible to non-expert readers–are introduced to formalise the discussion about the current state-of-the-art methods. Three case studies treating ongoing research are introduced and related to the conceptual fundamentals. The research is evaluated with regard to current barriers and future directions. In conclusion, modular precast construction is able to reduce emissions and increase productivity in the sector if researchers and firms coordinate the development of suitable technologies that bring value to critical stakeholders

Heterologous Overexpression and Mutagenesis of the Human Bile Salt Export Pump (ABCB11) Using DREAM (Directed REcombination-Assisted Mutagenesis)

Homologous recombination in Saccharomyces cerevisiae is a well-studied process. Here, we describe a yeast-recombination-based approach to construct and mutate plasmids containing the cDNA of the human bile salt export pump (BSEP) that has been shown to be unstable in E. coli. Using this approach, we constructed the necessary plasmids for a heterologous overexpression of BSEP in the yeast Pichia pastoris. We then applied a new site-directed mutagenesis method, DREAM (Directed REcombination-Assisted Mutagenesis) that completely bypasses E. coli by using S. cerevisiae as the plasmid host with high mutagenesis efficiency. Finally, we show how to apply this strategy to unstable non-yeast plasmids by rapidly turning an existing mammalian BSEP expression construct into a S. cerevisiae-compatible plasmid and analyzing the impact of a BSEP mutation in several mammalian cell lines

Optimierte Assemblierung seriengefertigter Betonfertigteile

Betonfertigteile werden für die Serienproduktion entwickelt und ihr Zusammenbau optimiert. Ersteres gelingt durch eine schnelle Wärmebehandlung sowie durch die Auflösung der Wände in modulare Wabenstrukturen. Der Einfluss der schnellen Wärmebehandlung auf die Materialeigenschaften des hochfesten Betons wurde empirisch untersucht. Eine schädigende sekundäre Ettringitbildung wurde nicht festgestellt und die Reduzierung der Normfestigkeit durch übliche Mikrofasermengen begrenzt. Die optimierte Modulanordnung erfolgt tragfähigkeitsbasiert und toleranzausgleichend mit Hilfe von Metaheuristiken. Zunächst werden die Module entsprechend ihrer Tragfähigkeit gezielt den entsprechend belasteten Bereichen der Wabenstrukturen zugeordnet, bis sich überall Module mit minimal zulässigen Querschnittsabmessungen und Wärmebehandlungsdauern befinden. Maßabweichungen der Module werden durch gezielte Permutation der Modulanordnung ausgeglichen, so dass Nacharbeiten nahezu vollständig vermieden werden

Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

Resource-efficient precast concrete elements can be produced using high-performance concrete (HPC). A heat treatment accelerates hardening and thus enables early stripping. To minimise damages to the concrete structure, treatment time and temperature are regulated. This leads to temperature treatment times of more than 24 h, what seems too long for quick serial production (flow production) of HPC. To overcome this shortcoming and to accelerate production speed, the heat treatment is started here immediately after concreting. This in turn influences the shrinkage behaviour and the concrete strength. Therefore, shrinkage is investigated on prisms made from HPC with and without steel fibres, as well as on short beams with reinforcement ratios of 1.8% and 3.1%. Furthermore, the flexural and compressive strengths of the prisms are measured directly after heating and later on after 28 d. The specimens are heat-treated between 1 and 24 h at 80 °C and a relative humidity of 60%. Specimens without heating serve for reference. The results show that the shrinkage strain is pronouncedly reduced with increasing temperature duration and rebar ratio. Moreover, the compressive and flexural strength decrease with decreasing temperature duration, whereby the loss of strength can be compensated by adding steel fibres

DEF of high-performance concrete with rapid, non-standard heat-treatment

High-performance concrete is often heat-treated to increase early strength. Standardized temperature conditions for at least 24 h and sulphate-resistant cement thereby preventing delayed ettringite formation (DEF). In contrast, this paper investigates the risk of DEF for rapidly heat-treated HPC with a minimum temperature duration of 1 h to achieve a rapid early strength for stripping. In addition, a binder is used that does not exhibit increased sulphate resistance. For this purpose, standard prisms (L x W x H = 16 × 4× 4 [cm]) are heat-treated at 80 °C between 1 and 6 h without a pre-storage time. Samples with a temperature duration of 24 h serve as reference. First, the pore structure is analyzed using Mercury porosimetry to identify damage to the concrete matrix due to the rapid heat treatment. The investigation of DEF is achieved by two common approaches. The sulphate resistance is determined by means of wet-dry cycles on specimens for 90 days, whereby the changes in mass and strain as well as the cracking pattern on the concrete surface serves as a qualitative evaluation criterion. In addition, the SVA method on specimens directly after heat treatment, which determines the change in mechanical properties and the swelling behaviour of the concrete, leads to a quantitative evaluation of sulfate resistance. The measured pore distribution of the samples shows a significant increase of the capillary pores of up to 109% for decreasing temperature durations. However, the porosity does not affect the sulphate resistance of the concrete. The wet-dry cycles cause no damage due to DEF, since the change in mass and strains decreases with increasing cycles from up to 62.7% to − 2.5%. Furthermore, no visual differences were detected on the concrete surface between specimens with and without sulphate attack. As a result of the SVA test, maximum absolute strains of about 0.1 mm/m occur that are below the limit value of 0.152 mm/m. Also, the mechanical properties do not show a reduction in strength, but even an increase in tensile strength. In conclusion, the high-performance concrete formulation used in combination with rapid heat treatment investigated here did not result in detectable damage due to DEF