Artificial neural network analysis of thermally stimulated depolarisation currents in Sb2O3-WO3-Li2O-Na2O glasses

AbstractThe mixed alkaline effect (MAE) is a well-known anomaly in glasses. It results in a nonlinear response of various physical properties on mixing of lkali ions in the glass. In this work, the thermal depolarization currents (TSDC) were studied in antimony oxides based glasses 60Sb2O3-20WO3-(20-x)Li2O-xNa2O (in mol%) for x= 0, 5,10, 15 a 20. TSDC methods are standardly used for characterization of different types of polarization in solids

Single fluorescent protein-based Ca2+ sensors with increased dynamic range

<p>Abstract</p> <p>Background</p> <p>Genetically encoded sensors developed on the basis of green fluorescent protein (GFP)-like proteins are becoming more and more popular instruments for monitoring cellular analytes and enzyme activities in living cells and transgenic organisms. In particular, a number of Ca²⁺sensors have been developed, either based on FRET (Fluorescence Resonance Energy Transfer) changes between two GFP-mutants or on the change in fluorescence intensity of a single circularly permuted fluorescent protein (cpFP).</p> <p>Results</p> <p>Here we report significant progress on the development of the latter type of Ca²⁺sensors. Derived from the knowledge of previously reported cpFP-based sensors, we generated a set of cpFP-based indicators with different spectral properties and fluorescent responses to changes in Ca²⁺concentration. Two variants, named Case12 and Case16, were characterized by particular high brightness and superior dynamic range, up to 12-fold and 16.5-fold increase in green fluorescence between Ca²⁺-free and Ca²⁺-saturated forms. We demonstrated the high potential of these sensors on various examples, including monitoring of Ca²⁺response to a prolonged glutamate treatment in cortical neurons.</p> <p>Conclusion</p> <p>We believe that expanded dynamic range, high brightness and relatively high pH-stability should make Case12 and Case16 popular research tools both in scientific studies and high throughput screening assays.</p

Structure and mechanism of the reversible photoswitch of a fluorescent protein

Proteins that can be reversibly photoswitched between a fluorescent and a nonfluorescent state bear enormous potential in diverse fields, such as data storage, in vivo protein tracking, and subdiffraction resolution light microscopy. However, these proteins could hitherto not live up to their full potential because the molecular switching mechanism is not resolved. Here, we clarify the molecular photoswitching mechanism of asFP595, a green fluorescent protein (GFP)-like protein that can be transferred from a nonfluorescent "off" to a fluorescent "on" state and back again, by green and blue light, respectively. To this end, we establish reversible photoswitching of fluorescence in whole protein crystals and show that the switching kinetics in the crystal is identical with that in solution. Subsequent x-ray analysis demonstrated that upon the absorption of a green photon, the chromophore isomerizes from a trans (off) to a cis (on) state. Molecular dynamics calculations suggest that isomerization occurs through a bottom hula twist mechanism with concomitant rotation of both bonds of the chromophoric methine ring bridge. This insight into the switching mechanism should facilitate the targeted design of photoswitchable proteins. Reversible photoswitching of the protein chromophore system within intact crystals also constitutes a step toward the use of fluorescent proteins in three-dimensional data recording

Monitoring of Gene Expression in Bacteria during Infections Using an Adaptable Set of Bioluminescent, Fluorescent and Colorigenic Fusion Vectors

A family of versatile promoter-probe plasmids for gene expression analysis was developed based on a modular expression plasmid system (pZ). The vectors contain different replicons with exchangeable antibiotic cassettes to allow compatibility and expression analysis on a low-, midi- and high-copy number basis. Suicide vector variants also permit chromosomal integration of the reporter fusion and stable vector derivatives can be used for in vivo or in situ expression studies under non-selective conditions. Transcriptional and translational fusions to the reporter genes gfpmut3.1, amCyan, dsRed2, luxCDABE, phoA or lacZ can be constructed, and presence of identical multiple cloning sites in the vector system facilitates the interchange of promoters or reporter genes between the plasmids of the series. The promoter of the constitutively expressed gapA gene of Escherichia coli was included to obtain fluorescent and bioluminescent expression constructs. A combination of the plasmids allows simultaneous detection and gene expression analysis in individual bacteria, e.g. in bacterial communities or during mouse infections. To test our vector system, we analyzed and quantified expression of Yersinia pseudotuberculosis virulence genes under laboratory conditions, in association with cells and during the infection process

Using conjoint analysis to understand preference for online survey layout

This study seeks to determine what participants prefer when taking online surveys with regard to conjoint design (number of concepts per screen) and format for grid questions. Respondents were mixed on their preference for two versus three concepts per screen. However, importance scores for incentive amount and type reversed when taking a conjoint exercise with two concepts per screen versus three concepts per screen. Participants seemed to focus more on incentives when presented with three concepts per screen than when presented with two concepts per screen. This finding was not expected and implications are discussed. In addition, the use of radio buttons versus drop-down menus in grid style questions was also explored. Respondents preferred radio buttons, and the means (repeated measures) were higher for responses for radio buttons than drop-down menus. </jats:p

Temperature microsensor/microactuator based on magnetic microwire for MEMS applications

The aim of this paper has been the development of a new type of temperature microsensor/microactuator working on the principle of the thermo-elastic (TE) deformation of multilayer magnetic microwire consisting of a glass-coated CoSiB metallic core and an electroplated CoNi external shell. The application of an electrical current along the microwire in the range 20-35 mA results in the TE mechanical bending of fixed sample, which is recorded. That mechanical deformation is interpreted to be a consequence of the resulting Joule heating, and its amplitude is directly proportional to the applied dc current in the mentioned range. Moreover, the direct proportionality between TE deformation and the resulting increase of temperature was experimentally confirmed. In this way, the new type of temperature microsensor/microactuator working on the principle of TE deformation has been developed. This opens new technological application of microwires as temperature microsensors and temperature-driven microactuators for micro-electro-mechanical system devices