The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show ...that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase space for three-phonon scattering processes, combined with the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optic ferroelectric mode.
Valorization of lignin to valuable chemicals and biofuels increases the economic viability of sustainable biorefineries. This work aimed at elucidating how the lignin structures recovered from ...various agricultural and industrial residues governed the downstream catalytic conversion. Three types of lignins, namely bio-enzymatic lignin (BL), organosolv lignin (OL), and Kraft lignin (KL), were fully characterized by HSQC-NMR, TGA, FTIR, and SEM to obtain a detailed description of their structures. In consideration of redox-active CuO and highly active carbon-modified boron nitride (BCN) in oxidative dehydrogenation, a two-dimensional CuO/BCN catalyst was prepared and explored in microwave-assisted lignin conversion to improve the yields of aromatic monomers. BL achieved the highest yield of monomers (10 wt% ) over the CuO/BCN catalyst after the 3
rd
cycle in 30 min under mild conditions (200 °C). The yields of bio-oils reached 70 wt% in 10 min when BL and OL were used as the substrate. High efficiency of the microwave-assisted reaction was illustrated by comparing with that of the hydrothermal reaction. This work demonstrated strong dependence of the conversion efficiency on the interunit linkages and functional groups of lignin structures. The strong metal-support interaction between CuO and BCN not only facilitated lignin depolymerization
via
the promoted electron transfer, but also enhanced the stability of Cu catalysts under hydrothermal conditions. In addition, elucidation of the catalyst redox evolution shed light on the role of the CuO/BCN catalyst in lignin depolymerization in recycle runs.
Valorization of lignin to valuable chemicals and biofuels increases the economic viability of sustainable biorefineries.
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•Lignin structures vary with different extraction process and affect product yields.•Native lignin enables effective valorization towards chemicals and biofuels.•Valorization ...strategies in relation to initial lignin structures are evaluated.•Advances in analytical technologies hold promise for lignin valorization.
Lignin is one of the most promising renewable sources for aromatic hydrocarbons, while effective depolymerization towards its constituent monomers is a particular challenge because of the structural complexity and stability. Intensive research efforts have been directed towards exploiting effective valorization of lignin for the production of bio-based platform chemicals and fuels. The present contribution aims to provide a critical review of key advances in the identification of exact lignin structure subjected to various fractionation technologies and demonstrate the key roles of lignin structures in depolymerization for unique functionalized products. Various technologies (e.g., thermocatalytic approaches, photocatalytic conversion, and mechanochemical depolymerization) are reviewed and evaluated in terms of feasibility and potential for further upgrading. Overall, advances in pristine lignin structure analysis and conversion technologies can facilitate recovery and subsequent utilization of lignin towards tailored commodity chemicals and fungible fuels.
Salamanders serve as important tetrapod models for developmental, regeneration and evolutionary studies. An extensive molecular toolkit makes the Mexican axolotl (Ambystoma mexicanum) a key ...representative salamander for molecular investigations. Here we report the sequencing and assembly of the 32-gigabase-pair axolotl genome using an approach that combined long-read sequencing, optical mapping and development of a new genome assembler (MARVEL). We observed a size expansion of introns and intergenic regions, largely attributable to multiplication of long terminal repeat retroelements. We provide evidence that intron size in developmental genes is under constraint and that species-restricted genes may contribute to limb regeneration. The axolotl genome assembly does not contain the essential developmental gene Pax3. However, mutation of the axolotl Pax3 paralogue Pax7 resulted in an axolotl phenotype that was similar to those seen in Pax3
and Pax7
mutant mice. The axolotl genome provides a rich biological resource for developmental and evolutionary studies.
Silver cluster-assembled materials (SCAMs), by virtue of their tunable structure, accessible surface area and excellent stability, hold great promise as highly efficient catalysts. Herein, we report ...a new SCAM Ag12(S t Bu)6(CF3COO)3(TPyP) n (denoted as Ag12TPyP) composed of a Ag12 chalcogenolate cluster core stabilized by porphyrinic ligands. Ag12TPyP showed superior sulfur mustard simulant (2-chloroethyl ethyl sulfide, CEES) degradation efficiency and achieved a half lifetime (t 1/2) of 1.5 min with 100% selectivity. The experimental results demonstrated that synergistic effects between the silver cluster and photosensitizer ligand promote the efficiency of the generation of singlet oxygen (1O2), which accelerates the decontamination rate. Additionally, benefiting from strong affinity between the silver cluster and CEES, Ag12TPyP exhibits a CEES uptake of 74.2 mg g–1. This work demonstrates that SCAMs offer a new route to the rational design of novel materials for the detoxification of mustard gas.
Despite significant clinical progress in cell and gene therapies, maximizing protein expression in order to enhance potency remains a major technical challenge. Here, we develop a high-throughput ...strategy to design, screen, and optimize 5' UTRs that enhance protein expression from a strong human cytomegalovirus (CMV) promoter. We first identify naturally occurring 5' UTRs with high translation efficiencies and use this information with in silico genetic algorithms to generate synthetic 5' UTRs. A total of ~12,000 5' UTRs are then screened using a recombinase-mediated integration strategy that greatly enhances the sensitivity of high-throughput screens by eliminating copy number and position effects that limit lentiviral approaches. Using this approach, we identify three synthetic 5' UTRs that outperform commonly used non-viral gene therapy plasmids in expressing protein payloads. In summary, we demonstrate that high-throughput screening of 5' UTR libraries with recombinase-mediated integration can identify genetic elements that enhance protein expression, which should have numerous applications for engineered cell and gene therapies.
Summary
Background
Tinea capitis is still common in developing countries, such as China. Its pathogen spectrum varies across regions and changes over time.
Objectives
This study aimed to clarify the ...current epidemiological characteristics and pathogen spectrum of tinea capitis in China.
Methods
A multicentre, prospective descriptive study involving 29 tertiary hospitals in China was conducted. From August 2019 to July 2020, 611 patients with tinea capitis were enrolled. Data concerning demography, risk factors and fungal tests were collected. When necessary, the pathogens were further identified by morphology or molecular sequencing in the central laboratory.
Results
Among all enrolled patients, 74·1% of the cases were in patients aged 2–8 years. The children with tinea capitis were mainly boys (56·2%) and were more likely than adults to have a history of animal contact (57·4% vs. 35·3%, P = 0·012) and zoophilic dermatophyte infection (73·5% vs. 47%). The adults were mainly female (83%) and were more likely than children to have anthropophilic agent infection (53% vs. 23·9%). The most common pathogen was zoophilic Microsporum canis (354, 65·2%), followed by anthropophilic Trichophyton violaceum (74, 13·6%). In contrast to the eastern, western and northeastern regions, where zoophilic M. canis predominated, anthropophilic T. violaceum predominated in central China (69%, P < 0·001), where the patients had the most tinea at other sites (20%) and dermatophytosis contact (26%) but the least animal contact (39%). Microsporum ferrugineum was the most common anthropophilic agent in the western area, especially in Xinjiang province.
Conclusions
Boys aged approximately 5 years were the most commonly affected group. Dermatologists are advised to pay more attention to the different transmission routes and pathogen spectra in different age groups from different regions.
What is already known about this topic?
Tinea capitis is an infection of the scalp and hair caused by dermatophytes and is still common in developing countries. Prepubertal children are mainly affected.
The pathogen spectrum of tinea capitis varies across different geographical areas and changes over time.
Nationwide prospective epidemiological surveys of tinea capitis in China are rare and out of date.
What does this study add?
This study provides data concerning the epidemiological characteristics and pathogen spectrum of tinea capitis in contemporary China.
Boys aged approximately 5 years were most commonly affected and were more likely than adults to have zoophilic dermatophyte infection.
The main pathogens of tinea capitis in China are zoophilic dermatophytes, mainly Microsporum canis. In contrast to the other regions, the predominant pathogens in central China are anthropophilic dermatophytes.
Plain language summary available online
Topological materials may exhibit Hall-like currents flowing transversely to the applied electric field even in the absence of a magnetic field. In graphene superlattices, which have broken inversion ...symmetry, topological currents originating from graphene’s two valleys are predicted to flow in opposite directions and combine to produce long-range charge neutral flow. We observed this effect as a nonlocal voltage at zero magnetic field in a narrow energy range near Dirac points at distances as large as several micrometers away from the nominal current path. Locally, topological currents are comparable in strength with the applied current, indicating large valley-Hall angles. The long-range character of topological currents and their transistor-like control by means of gate voltage can be exploited for information processing based on valley degrees of freedom.
This paper focuses on the problem of globally exponential synchronization of impulsive dynamical networks. Two types of impulses are considered: synchronizing impulses and desynchronizing impulses. ...In previous literature, all of the results are devoted to investigating these two kinds of impulses separately. Thus a natural question arises: Is there any
unified synchronization criterion which is simultaneously effective for synchronizing impulses and desynchronizing impulses? In this paper, a
unified synchronization criterion is derived for directed impulsive dynamical networks by proposing a concept named “average impulsive interval”. The derived criterion is theoretically and numerically proved to be less conservative than existing results. Numerical examples including scale-free and small-world structures are given to show that our results are applicable to large-scale networks.
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