Superelastic conducting fibers with improved properties and functionalities are needed for diverse applications. Here we report the fabrication of highly stretchable (up to 1320%) sheath-core ...conducting fibers created by wrapping carbon nanotube sheets oriented in the fiber direction on stretched rubber fiber cores. The resulting structure exhibited distinct short- and long-period sheath buckling that occurred reversibly out of phase in the axial and belt directions, enabling a resistance change of less than 5% for a 1000% stretch. By including other rubber and carbon nanotube sheath layers, we demonstrated strain sensors generating an 860% capacitance change and electrically powered torsional muscles operating reversibly by a coupled tension-to-torsion actuation mechanism. Using theory, we quantitatively explain the complementary effects of an increase in muscle length and a large positive Poisson's ratio on torsional actuation and electronic properties.
Substrate channeling is a process of transferring the product of one enzyme to an adjacent cascade enzyme or cell without complete mixing with the bulk phase. Such phenomena can occur in vivo, in ...vitro, or ex vivo. Enzyme–enzyme or enzyme–cell complexes may be static or transient. In addition to enhanced reaction rates through substrate channeling in complexes, numerous potential benefits of such complexes are protection of unstable substrates, circumvention of unfavorable equilibrium and kinetics imposed, forestallment of substrate competition among different pathways, regulation of metabolic fluxes, mitigation of toxic metabolite inhibition, and so on. Here we review numerous examples of natural and synthetic complexes featuring substrate channeling. Constructing synthetic in vivo, in vitro or ex vivo complexes for substrate channeling would have great biotechnological potentials in metabolic engineering, multi-enzyme-mediated biocatalysis, and cell-free synthetic pathway biotransformation (SyPaB).
We present an empirical stellar spectra library created using spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) DR5. This library represents a uniform data set ...ranging from 3750 through 8500 K in effective temperature (Teff), from −2.5 through +1.0 dex in metallicity (Fe/H), and from 0 to 5.0 dex in gravity (log g). The spectra in the library have resolutions R ∼ 1800, with well-calibrated fluxes and rest-framed wavelengths. Using a large number of red stars observed by LAMOST, we generated denser K-type templates to fill in data missing from current empirical spectral libraries, particularly the late K type. For K giants, we calibrated the spectroscopic surface gravities against the asteroseismic surface gravities. To verify the reliability of the parameters labeled for this library, we performed an internal cross-validation using a χ2 minimization method to interpolate the parameters of each individual spectrum using the remaining spectra in the library. We obtained precisions of 41 K, 0.11 dex, and 0.05 dex for Teff, log g, and Fe/H, respectively, which means the templates are labeled with correct stellar parameters. Through external comparisons, we confirmed that measurements of the stellar parameters through this library can achieve accuracies of approximately 125 K in Teff, 0.1 dex in Fe/H and 0.20 dex in log g without systematic offset. This empirical library is useful for stellar parameter measurements because it has large parameter coverage and full wavelength coverage from 3800 to 8900 .
We report observations of gamma-ray emissions with energies in the 100-TeV energy region from the Cygnus region in our Galaxy. Two sources are significantly detected in the directions of the Cygnus ...OB1 and OB2 associations. Based on their positional coincidences, we associate one with a pulsar PSR J2032 + 4127 and the other mainly with a pulsar wind nebula PWN G75.2 + 0.1, with the pulsar moving away from its original birthplace situated around the centroid of the observed gamma-ray emission. This work would stimulate further studies of particle acceleration mechanisms at these gamma-ray sources.
• The lignin content of feedstock has been proposed as one key agronomic trait impacting biofuel production from lignocellulosic biomass. 4‐Coumarate:coenzyme A ligase (4CL) is one of the key enzymes ...involved in the monolignol biosynthethic pathway. • Two homologous 4CL genes, Pv4CL1 and Pv4CL2, were identified in switchgrass (Panicum virgatum) through phylogenetic analysis. Gene expression patterns and enzymatic activity assays suggested that Pv4CL1 is involved in monolignol biosynthesis. Stable transgenic plants were obtained with Pv4CL1 down‐regulated. • RNA interference of Pv4CL1 reduced extractable 4CL activity by 80%, leading to a reduction in lignin content with decreased guaiacyl unit composition. Altered lignification patterns in the stems of RNAi transgenic plants were observed with phloroglucinol‐HCl staining. The transgenic plants also had uncompromised biomass yields. After dilute acid pretreatment, the low lignin transgenic biomass had significantly increased cellulose hydrolysis (saccharification) efficiency. • The results demonstrate that Pv4CL1, but not Pv4CL2, is the key 4CL isozyme involved in lignin biosynthesis, and reducing lignin content in switchgrass biomass by silencing Pv4CL1 can remarkably increase the efficiency of fermentable sugar release for biofuel production.
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