Synthesis of poly(styrene-b-isobutylene-b-styrene) triblock copolymer by ATRP

Summary A poly(styrene-b-isobutylene-b-styrene) triblock copolymer has been prepared by a two-step process. Polyisobutylene with M_n= 6600 and M_w/M_n= 1.12 functionalized with phenol at both ends was reacted with 2-bromopropionyl chloride to form a macroinitioator for atom transfer radical polymerization (ATRP). The synthesized difunctional PIB macroinitiator was subsequently heated with styrene xylene solution in the second step to 110°C under conditions for ATRP using the copper coordination complex CuBr/bipyridine. Both the macroinitiator and the triblock copolymer were characterized by ¹H NMR and SEC. The triblock copolymer with around 25% polystyrene was found to have a narrow molecular weight distribution of 1.20. Received: 4 October 1998/Revised version: 29 October 1998/Accepted: 3 November 1998     

The Jacalin-Related Lectin HvHorcH Is Involved in the Physiological Response of Barley Roots to Salt Stress

Salt stress tolerance of crop plants is a trait with increasing value for future food production. In an attempt to identify proteins that participate in the salt stress response of barley, we have used a cDNA library from salt-stressed seedling roots of the relatively salt-stress-tolerant cv. Morex for the transfection of a salt-stress-sensitive yeast strain (Saccharomyces cerevisiae YSH818 Δhog1 mutant). From the retrieved cDNA sequences conferring salt tolerance to the yeast mutant, eleven contained the coding sequence of a jacalin-related lectin (JRL) that shows homology to the previously identified JRL horcolin from barley coleoptiles that we therefore named the gene HvHorcH. The detection of HvHorcH protein in root extracellular fluid suggests a secretion under stress conditions. Furthermore, HvHorcH exhibited specificity towards mannose. Protein abundance of HvHorcH in roots of salt-sensitive or salt-tolerant barley cultivars were not trait-specific to salinity treatment, but protein levels increased in response to the treatment, particularly in the root tip. Expression of HvHorcH in Arabidopsis thaliana root tips increased salt tolerance. Hence, we conclude that this protein is involved in the adaptation of plants to salinity.     

Mouse Liver Compensates Loss of Sgpl1 by Secretion of Sphingolipids into Blood and Bile

Sphingosine 1 phosphate (S1P) lyase (Sgpl1) catalyses the irreversible cleavage of S1P and thereby the last step of sphingolipid degradation. Loss of Sgpl1 in humans and mice leads to accumulation of sphingolipids and multiple organ injuries. Here, we addressed the role of hepatocyte Sgpl1 for regulation of sphingolipid homoeostasis by generating mice with hepatocyte-specific deletion of Sgpl1 (Sgpl1^HepKO mice). Sgpl1^HepKO mice had normal body weight, liver weight, liver structure and liver enzymes both at the age of 8 weeks and 8 months. S1P, sphingosine and ceramides, but not glucosylceramides or sphingomyelin, were elevated by ~1.5–2-fold in liver, and this phenotype did not progress with age. Several ceramides were elevated in plasma, while plasma S1P was normal. Interestingly, S1P and glucosylceramides, but not ceramides, were elevated in bile of Sgpl1^HepKO mice. Furthermore, liver cholesterol was elevated, while LDL cholesterol decreased in 8-month-old mice. In agreement, the LDL receptor was upregulated, suggesting enhanced uptake of LDL cholesterol. Expression of peroxisome proliferator-activated receptor-γ, liver X receptor and fatty acid synthase was unaltered. These data show that mouse hepatocytes largely compensate the loss of Sgpl1 by secretion of accumulating sphingolipids in a specific manner into blood and bile, so that they can be excreted or degraded elsewhere.     

It's fun to do things together: Two cases of explorative user studies

This paper describes two explorative user studies conducted in a research project called Maypole. The purpose of the first user study was to understand how children thought communication with personal technologies could be fun. The second study focused on what children thought was fun in taking and editing digital images. In both studies, children aged 7–12 were given existing personal technologies to use in their own environment for one week. After that, a focus group was held with the children in order to discuss what they thought was fun in using the technologies.The results of the two user studies illustrate how fun in using personal technologies could relate to a user's social behaviour, and not only to human-computer interaction. Therefore, designers are encouraged to explore further the social aspects of fun in their creations. Moreover, the two studies illustrate some methodological problems in studying a user's experience of fun, which refer to a need for more public research on methods.     

Semi-Automated High-Throughput Substrate Screening Assay for Nucleoside Kinases

Nucleoside kinases (NKs) are key enzymes involved in the in vivo phosphorylation of nucleoside analogues used as drugs to treat cancer or viral infections. Having different specificities, the characterization of NKs is essential for drug design and nucleotide analogue production in an in vitro enzymatic process. Therefore, a fast and reliable substrate screening method for NKs is of great importance. Here, we report on the validation of a well-known luciferase-based assay for the detection of NK activity in a 96-well plate format. The assay was semi-automated using a liquid handling robot. Good linearity was demonstrated (r² > 0.98) in the range of 0–500 µM ATP, and it was shown that alternative phosphate donors like dATP or CTP were also accepted by the luciferase. The developed high-throughput assay revealed comparable results to HPLC analysis. The assay was exemplarily used for the comparison of the substrate spectra of four NKs using 20 (8 natural, 12 modified) substrates. The screening results correlated well with literature data, and additionally, previously unknown substrates were identified for three of the NKs studied. Our results demonstrate that the developed semi-automated high-throughput assay is suitable to identify best performing NKs for a wide range of substrates.     

ACHEMA 2022: Membranes and Membrane Processes

Numerous companies working in the field of membrane development, membrane production, and membrane separation engineering were present at ACHEMA 2022. Compared to the last ACHEMA in 2018, there were fewer attending companies and only few new topics since development has been blocked partially by the pandemic situation and the subsequent restrictions of this years. Nevertheless, some new developments have been identified concerning process design as well as ceramic and polymeric systems.     

Construction and evaluation of gRNA arrays for multiplex CRISPR-Cas9

Endonuclease system CRISPR-Cas9 represents a powerful toolbox for the budding yeast's Saccharomyces cerevisiae genome perturbation. The resulting double-strand breaks are preferentially repaired via highly efficient homologous recombination, which subsequently leads to marker-free genome editing. The goal of this study was to evaluate precise targeting of multiple loci simultaneously. To construct an array of independently expressing guide RNAs (gRNAs), the genes encoding them were assembled through a BioBrick construction procedure. We designed a multiplex CRISPR-Cas9 system for targeting 6 marker genes, whereby the gRNA array was expressed from a single plasmid. To evaluate the performance of the gRNA array, the activity of the designed system was assessed by the success rate of the introduction of perturbations within the target loci: successful gRNA expression, followed by target DNA double-strand breaks formation and their repair by homologous recombination led to premature termination of the coding sequence of the marker genes, resulting in the prevention of growth of the transformants on the corresponding selection media. In conclusion, we successfully introduced up to five simultaneous perturbations within single cells of yeast S. cerevisiae using the multiplex CRISPR-Cas9 system. While this has been done before, we here present an alternative sequential BioBrick assembly with the capability to accommodate many highly similar gRNA-expression cassettes, and an exhaustive evaluation of their performance.     

The hydromorphology index IHM based on fish requirements

Stream ecosystems are diverse and dynamic habitats that are strongly influenced by the direct and indirect consequences of human interventions. Several initiatives have been started all over Europe to satisfy the European guidelines for the protection of local water bodies, but a standardised procedure across national borders fulfilling all relevant aspects and parameters of the Water Framework Directive (WFD) does not exist. In this context, we propose a new methodical approach based on salmonid fish populations to assess stream quality to increase the comparability of individual assessments due to standardized survey and evaluation methods for hydromorphology. Our approach is based on the Austrian and Italian methods, which account for the European standards, and it has been tested in 81 stream sections representative of different site and anthropogenic use conditions in the European Alps. The assessment procedure is composed of a set of 11 indicators, which were selected to evaluate longitudinal and lateral morphological and temporal dynamics of morphological and hydrological conditions. The indicators were combined into three indices, the morphology (I_M), hydrology (I_H), and hydromorphology indices (I_HM), to obtain a holistic picture with as few parameters as possible. The definition of indicators and indices, their methodical implementation and practical testing in the field, were carried out by an interdisciplinary team of international experts. The resulting and tested field manual is included with this publication as Supplementary material. The applicability, strengths, and weaknesses of the approach are discussed in the present paper.     

Improved Thermal and Mechanical Properties of [Ca24Al28O64]4+(4e−) Electride Ceramic by Adding Mo Metal

The low-work function material [Ca₂₄Al₂₈O₆₄]⁴⁺(4e⁻)—named as C12A7:e- or electride—is a promising candidate to replace established materials such as BaO–W or LaB₆ electron emitters because of its good reported electron emission in plasma environments and decent chemical inertness. However, it has poor thermal conductivity and low mechanical behavior. Therefore, cracks due to thermal shock occur in applications under thermal load, when used as a thermionic emitter. The addition of a metal with high thermal conductivity to create a ceramic–metal composite (CerMet) is evident. Molybdenum has a very high thermal conductivity and a coefficient of thermal expansion comparable to C12A7:e-. This allows the crack-free sintering of a composite ceramic made of C12A7:e- and Mo with improved thermal and mechanical properties as well as still low work function of the C12A7:e-. Herein, the C12A7:e-/Mo CerMets are characterized in terms of their thermal conductivity, thermal expansion coefficient (CTE), hardness, toughness K_1C, and strength as a function of Mo content. The CerMets have been tested in a plasma-based cathode with disk-shaped emitters for electron emission characteristics. An optimal range of the Mo content for the stability of the plasma discharge and the required discharge potential has been evaluated.