Contribution of reutericyclin production to the stable persistence of Lactobacillus reuteri in an industrial sourdough fermentation

Reutericyclin is a small molecular weight antibiotic produced by the sourdough isolate Lactobacillus reuteri LTH2584. This strain was isolated from an industrial sourdough, SER, in 1988. To determine whether reutericyclin formation contributes to the stable persistence of L. reuteri in sourdough, evaluations were made on whether reutericyclin-producing strains were among L. reuteri isolates from the SER sourdough obtained in 1994 and 1998. These strains were characterised on species and strain level by physiological tests and randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) patterns. Reutericyclin production in dough was evaluated by two methods, a bioassay and HPLC. Throughout 10 years of continuous propagation, reutericyclin-producing L. reuteri strains were present in SER sourdough. All isolates exhibited similar physiological properties and molecular typing revealed closely related patterns. Two isolates obtained in 1994 and 1998 were identical. Reutericyclin produced in situ by L. reuteri was active in dough against reutericyclin-sensitive L. sanfranciscensis. The reutericyclin concentration in dough fermented with L. reuteri was 5 mg kg(-1). The results indicate that reutericyclin production contributed to the stable persistence of L. reuteri in sourdough. Because reutericyclin is produced in active concentrations during sourdough fermentations, it is a suitable candidate for use as natural preservative.     

Brief Introduction to Neutron Scattering and Global Neutron User Facilities

Neutrons play a vital role as a powerful tool in basic science and applied research. In this article, the basic properties of neutrons, their generation and detection, as well as some fundamental aspects of neutron instrumentation are introduced. Neutron user facilities, at which the user may obtain more specific information and apply for beam time, are also discussed.     

Effect of aromatic substitution on the kinetics and properties of epoxy cured tri-phenylether amines

The reaction kinetics and structure property relationships of isomeric tri-aromatic ether-linked amines based on the structure bis (aminophenoxy) benzene, cured with diglycidyl ether of bisphenol F (BisF) are investigated in this study. Reaction kinetics are explored using rheological and calorimetric measurements, whereas structure property relationships are determined from their flexural properties, dynamic mechanical properties (DMTA), and thermogravimetric analysis (TGA). A BisF network cured with 4,4 diamino diphenyl sulphone (44 DDS) is used as a benchmark to represent a commercially available high-performance resin system. Varying the substitution of the ether linkages on the aromatic groups from ortho, meta to para was found to have a significant impact on reactivity and network properties after cure. The variations are explained in terms of inductive and resonance effects primarily acting on the outer aromatic rings. Interestingly, however, these same effects acting on the central aromatic ring also impact upon reactivity despite their proximity from the amines. Mechanical and thermal properties are explained by changes in the short-range molecular mobility within the network architecture such as phenylene rotations or π flips and are experimentally validated from the breadth and position of the subambient γ relaxations. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47383.     

Metal–Organic Hybrid Interface States of A Ferromagnet/Organic Semiconductor Hybrid Junction as Basis For Engineering Spin Injection in Organic Spintronics

Electrons in organic semiconductors (OSC) possess remarkably long spin relaxation times. Hybrid spintronic devices that combine OSC with ferromagnetic (FM) substrates are therefore expected to provide a route to devices with improved and new functionalities. A crucial role is played by the FM‐OSC interface which governs the spin injection into the OSC. Using spin‐resolved photoelectron spectroscopy and ab initio calculations we study here such possible injection channels in metal phthalocyanines (MPc). We report the first direct observation of the successful engineering of different spin‐selective hybrid interface states at the Fermi level of a FM‐OSC hybrid junction only by changing the central metal atom of a MPc. Our results demonstrate that tailoring the chemical interaction at the FM‐OSC interface is a promising way to modify the spin injection channels and thus the spin injection capability.     

Detecting Bacterial Cell Viability in Few µL Solutions from Impedance Measurements on Silicon-Based Biochips

Using two different types of impedance biochips (PS5 and BS5) with ring top electrodes, a distinct change of measured impedance has been detected after adding 1–5 µL (with dead or live Gram-positive Lysinibacillus sphaericus JG-A12 cells to 20 µL DI water inside the ring top electrode. We relate observed change of measured impedance to change of membrane potential of L. sphaericus JG-A12 cells. In contrast to impedance measurements, optical density (OD) measurements cannot be used to distinguish between dead and live cells. Dead L. sphaericus JG-A12 cells have been obtained by adding 0.02 mg/mL of the antibiotics tetracycline and 0.1 mg/mL chloramphenicol to a batch with OD0.5 and by incubation for 24 h, 30 °C, 120 rpm in the dark. For impedance measurements, we have used batches with a cell density of 25.5 × 10⁸ cells/mL (OD8.5) and 270.0 × 10⁸ cells/mL (OD90.0). The impedance biochip PS5 can be used to detect the more resistive and less capacitive live L. sphaericus JG-A12 cells. Also, the impedance biochip BS5 can be used to detect the less resistive and more capacitive dead L. sphaericus JG-A12 cells. An outlook on the application of the impedance biochips for high-throughput drug screening, e.g., against multi-drug-resistant Gram-positive bacteria, is given.     

Particulate Coatings with Optimized Haze Properties

The haze factor, which describes the fraction of light that is scattered when passing through a transparent material, is of general importance for any optical device, from milk glass shielding visibility while providing ambient lighting to solar cells that are optimized by sophisticated light management layers. Often, such active layers are fabricated from particulate materials that are deposited as thin films on a substrate. Here, the effect of structural arrangement, position, and orientation of particles on the resulting haze factor is investigated. A mathematical optimization model that iteratively alters the particle layer structure to maximize or minimize the haze factor for a range of optimization scenarios is designed. Colloidal self‐assembly techniques are then used to replicate typical particle structures found in the optimized designs and correlate the macroscopically measured haze values to the predictions of the optimization. The results indicate general design rules that control the haze value in particle layers. Non close‐packed structures with distributed scatterers and high degrees of order provide minimal haze values while chain‐like arrangements and small clusters maximize the haze of a particle layer. Finally, the findings are transferred to metal nanohole films as model transparent electrodes with controlled haze values.     

Antecedents of Coordination Effectiveness of Software Developer Dyads From Interacting Teams: An Empirical Investigation

Among the numerous reasons for software project failure, coordination problems are especially salient. Prior studies on coordination in software development are confined to team internal coordination and do not explicitly differentiate team internal and external coordination processes. This study presents a research model to explain the antecedents of coordination effectiveness of software developer dyads from interacting teams. Dyads in this study refer to software developer pairs where each member comes from a different team. We explore the antecedents by integrating interpersonal and technology-based coordination. We test this model using data collected from 59 software developer Dyads from interacting teams as well as from software developer leaders. The results reveal that the implicit knowledge sharing has a significant positive impact on coordination effectiveness. The use of explicit knowledge sharing and coordination technology have no statistically significant impact on coordination effectiveness although the teams studied were working predominantly in a collocated mode. Mutual trust and project commitment have a significant impact on knowledge sharing with mutual trust directly affecting both implicit and explicit knowledge sharing. Project commitment also has a direct impact on explicit knowledge sharing and mutual trust, but it does not directly affect implicit knowledge sharing. Theoretical and practical contributions are discussed. Limitations of this study are identified. Future research directions are also presented.     

Deposition of HfO2 on InAs by atomic-layer deposition

Metal–oxide–semiconductor (MOS) capacitors are formed on bulk InAs substrates by atomic-layer deposition (ALD) of HfO₂. Prior to film growth, InAs substrates receive a wet-chemical treatment of HCl, buffered HF (BHF), or (NH₄)₂S. Hafnium dioxide films are grown using 75 ALD cycles with substrate temperatures of 100, 200, and 300 °C. Substrate temperature is found to have a significant influence on the current–voltage (I–V) and capacitance–voltage (C–V) characteristics of the capacitors, while the influence of substrate pretreatment manifests itself in interface trap density, D_it, as measured by the Terman method.     

Rheology Pathway to Macroscale Ordered Nanostructures of Polymeric Nanotemplates: Nanopores,Nanosheets and Nanofibers

Summary: The creation of nanotemplates under dynamic shear flow conditions is described. The structures used are based on the self‐organization of comb‐coil‐like diblock copolymer systems with two intrinsic length scales, resulting from combining diblock copolymers with hydrogen‐bonding amphiphiles. Rheological data of polymeric supramolecular order formation are studied under oscillating shear flow conditions and it was observed that the order of the polymeric nanodomains can be extended to macroscopic distances. It is proposed that the key success factor to obtain highly ordered samples is to perform the orientation process using appropriate rheological conditions (temperature, frequency and strain) selected such that the ratio of the elastic component G′ to the viscous component G″ is larger than 1. This observation was used to select the rheological parameters for the three different samples investigated, where three different types of nanotemplates are observed after extracting the hydrogen‐bonding amphiphile; nanosheets, hollow cylinders and nanofibres. SAXS is primarily used to inspect the resulting structures. Additionally, AFM and TEM were utilized to image the morphologies and to further act as visual proof for the efficiency of the rheological orientation process.

AFM phase image of PS‐b‐P4VP nanosheets on Si wafer substrate after extracting the PDP.