New Beta-lactamases in Candidate Phyla Radiation: Owning Pleiotropic Enzymes Is a Smart Paradigm for Microorganisms with a Reduced Genome

The increased exploitation of microbial sequencing methods has shed light on the high diversity of new microorganisms named Candidate Phyla Radiation (CPR). CPR are mainly detected via 16S rRNA/metabarcoding analyses or metagenomics and are found to be abundant in all environments and present in different human microbiomes. These microbes, characterized by their symbiotic/epiparasitic lifestyle with bacteria, are directly exposed to competition with other microorganisms sharing the same ecological niche. Recently, a rich repertoire of enzymes with antibiotic resistance activity has been found in CPR genomes by using an in silico adapted screening strategy. This reservoir has shown a high prevalence of putative beta-lactamase-encoding genes. We expressed and purified five putative beta-lactamase sequences having the essential domains and functional motifs from class A and class B beta-lactamase. Their enzymatic activities were tested against various beta-lactam substrates using liquid chromatography-mass spectrometry (LC-MS) and showed some beta-lactamase activity even in the presence of a beta-lactamase inhibitor. In addition, ribonuclease activity was demonstrated against RNA that was not inhibited by sulbactam and EDTA. None of these proteins could degrade single- and double-stranded-DNA. This study is the first to express and test putative CPR beta-lactamase protein sequences in vitro. Our findings highlight that the reduced genomes of CPR members harbor sequences encoding for beta-lactamases known to be multifunction hydrolase enzymes.     

Scene-based nonuniformity correction with video sequences and registration

We describe a new, to our knowledge, scene-based nonuniformity correction algorithm for array detectors. The algorithm relies on the ability to register a sequence of observed frames in the presence of the fixed-pattern noise caused by pixel-to-pixel nonuniformity. In low-to-moderate levels of nonuniformity, sufficiently accurate registration may be possible with standard scene-based registration techniques. If the registration is accurate, and motion exists between the frames, then groups of independent detectors can be identified that observe the same irradiance (or true scene value). These detector outputs are averaged to generate estimates of the true scene values. With these scene estimates, and the corresponding observed values through a given detector, a curve-fitting procedure is used to estimate the individual detector response parameters. These can then be used to correct for detector nonuniformity. The strength of the algorithm lies in its simplicity and low computational complexity. Experimental results, to illustrate the performance of the algorithm, include the use of visible-range imagery with simulated nonuniformity and infrared imagery with real nonuniformity.     

Symbol synchronization using signal samples and interpolation

A method for symbol synchronization using two unsynchronized signal samples per symbol is presented. Signal values between the sample points are calculated by interpolation and then processed digitally to find a suitable strobe point. The interpolated value at the strobe point is used for data detection or input to an equalizer. Simulations show that low variance timing estimates can be made for pulses with raised-cosine spectra degraded by quadratic delay distortion     

On the Cooling Rate-Microstructure Relationship in Molten Metal Gas Atomization

Metallurgical and Materials Transactions A - Gas atomization is the most used powder production technique since it provides good control on particles shape, surface oxidation and dimension. It is a...     

电缆与连接器(六)

3．2．7关于绕线器件（电容、变压器、扼流圈等）的问题 对于绕线（感性）器件,需要从三个方面进行考虑：杂散磁场的控制、特性参数随电流和温度的变化以及电阻特性。     

Core–shell adsorbents by electrospun MOF-polymer composites with improved adsorption properties: Theory and experiments

A new class of core–shell adsorbents has been created by electrospun metal–organic framework (MOF) particles embedded in polymer nanofibers, which have provided many unique properties compared to the existing MOF coating technologies. For the first time, we demonstrate the improved adsorption selectivity of CO₂ over N₂ using electrospun polymer/ZIF-8 adsorbents in experiments. Furthermore, an analytical model based on the assumption that the diffusivity in core is 10 times higher than that in shell is developed to describe the theory of improved selectivity for core–shell adsorbents that is validated against a more accurate finite element model developed in COMSOL. Our model shows three regimes including exclusive shell uptake, linear core uptake, and asymptotic core uptake. These regimes are related to material properties and uptake times, which could be used as design criteria to balance core stability, maximum selectivity, and maximum uptake. An advanced HAADF STEM tomography (Movie S1 ) shows that the shell thickness in the case of polymer/ZIF-8 is on the order of 10 nm, allowing the regime of maximum selectivity to be realized. Kinetically limited adsorption tests at 45°C demonstrate that these composite fibers can perform in a regime of selectivity and uptake for the separation of CO₂ and N₂ that is unobtainable by either the MOF or fiber independently, showing a great potential for postcombustion CO₂ capture.     

Association of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) with age of puberty among children living near a chemical plant

Animal studies suggest that perfluorocarbons (PFCs) may alter sexual maturation. Relationships of human PFC exposure with puberty are not clear. We conducted a cross-sectional study to investigate whether perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) were associated with indicators of sexual maturation in a 2005-2006 survey of residents with PFOA water contamination from the Mid-Ohio Valley. Participants were 3076 boys and 2931 girls aged 8-18 years. They were classified as having reached puberty based on either hormone levels (total >50 ng/dL and free >5 pg/mL testosterone in boys and estradiol >20 pg/mL in girls) or onset of menarche. We estimated the odds of having reached puberty classified by these criteria and the fitted median age of reaching puberty in relation to serum PFOA and PFOS concentrations measured when puberty status was assigned. For boys, there was a relationship of reduced odds of reached puberty (raised testosterone) with increasing PFOS (delay of 190 days between the highest and lowest quartile). For girls, higher concentrations of PFOA or PFOS were associated with reduced odds of postmenarche (130 and 138 days of delay, respectively). In conclusion, our study showed a later age of puberty in this population correlated with PFC concentrations.     

Crystallization-Directed Anisotropic Electroactuation in Selectively Solvated Olefinic Thermoplastic Elastomers: A Thermal and (Electro)Mechanical Property Study

Dielectric elastomers (DEs), a class of soft electroactive polymers that change size upon exposure to an external electric field, constitute an increasingly important class of stimuli-responsive polymers due primarily to their large actuation strains, facile and low-cost fabrication, scalability, and mechanical robustness. Unless purposefully constrained, most DEs exhibit isotropic actuation wherein size changes are the same in all actuation directions. Previous studies of DEs containing oriented, stiff fibers have demonstrated, however, that anisotropic actuation along a designated direction is more electromechanically efficient since this design eliminates energy expended in nonessential directions. To identify an alternative, supramolecular-level route to anisotropic electroactuation, we investigate the thermal and mechanical properties of novel thermoplastic elastomer gels composed of a selectively solvated olefinic block copolymer that not only microphase-separates but also crystallizes upon cooling from the solution state. While these materials possess remarkable mechanical attributes (e.g., giant strains in excess of 4000%), their ability to be strain-conditioned enables huge anisotropic actuation levels, measured to be greater than 30 from the ratio of orthogonal actuation strains. This work establishes that crystallization-induced anisotropic actuation can be achieved with these DEs.