Regulations currently in force enable to claim that the lead content in perovskite solar cells is low enough to be safe, or no more dangerous, than other electronics also containing lead. However, ...the actual environmental impact of lead from perovskite is unknown. Here we show that the lead from perovskite leaking into the ground can enter plants, and consequently the food cycle, ten times more effectively than other lead contaminants already present as the result of the human activities. We further demonstrate that replacing lead with tin represents an environmentally-safer option. Our data suggest that we need to treat the lead from perovskite with exceptional care. In particular, we point out that the safety level for lead content in perovskite-based needs to be lower than other lead-containing electronics. We encourage replacing lead completely with more inert metals to deliver safe perovskite technologies.
Hydrogel-based devices are widely used as flexible electronics, biosensors, soft robots, and intelligent human-machine interfaces. In these applications, high stretchability, low hysteresis, and ...anti-fatigue fracture are essential but can be rarely met in the same hydrogels simultaneously. Here, we demonstrate a hydrogel design using tandem-repeat proteins as the cross-linkers and random coiled polymers as the percolating network. Such a design allows the polyprotein cross-linkers only to experience considerable forces at the fracture zone and unfold to prevent crack propagation. Thus, we are able to decouple the hysteresis-toughness correlation and create hydrogels of high stretchability (~1100%), low hysteresis (< 5%), and high fracture toughness (~900 J m
). Moreover, the hydrogels show a high fatigue threshold of ~126 J m
and can undergo 5000 load-unload cycles up to 500% strain without noticeable mechanical changes. Our study provides a general route to decouple network elasticity and local mechanical response in synthetic hydrogels.
The diagnosis of biliary atresia (BA) remains a clinical challenge because affected infants have signs, symptoms, and serum liver biochemistry that are also seen in those with other causes of ...neonatal cholestasis (non‐BA). However, an early diagnosis and prompt surgical treatment are required to improve clinical outcome. Recently, the relative abundance of serum matrix metalloproteinase‐7 (MMP‐7) was suggested to have discriminatory features for infants with BA. To test the hypothesis that elevated serum concentration of MMP‐7 is highly diagnostic for BA, we determined the normal serum concentration of MMP‐7 in healthy control infants, and then in 135 consecutive infants being evaluated for cholestasis. The median concentration for MMP‐7 was 2.86 ng/mL (interquartile range, IQR: 1.32‐5.32) in normal controls, 11.47 ng/mL (IQR: 8.54‐24.55) for non‐BA, and 121.1 ng/mL (IQR: 85.42‐224.4) for BA (P < 0.0001). The area under the curve of MMP‐7 for the diagnosis of BA was 0.9900 with a cutoff value of 52.85 ng/mL; the diagnostic sensitivity and specificity were 98.67% and 95.00%, respectively, with a negative predictive value of 98.28%. Conclusion: Serum MMP‐7 assay has high sensitivity and specificity to differentiate BA from other neonatal cholestasis, and may be a reliable biomarker for BA.
Nanoscale schwertmannites were fabricated and studied for their efficient degradation of 4–nitrophenol in Fenton–like processes.
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•Uniform nanoscale schwertmannites (nano-SCH) were ...prepared via PVP assisted pathway.•Nano-SCH was applied as efficient Fenton–like catalysts at various conditions.•Hydroxyl radicals were dominant active species for nitrophenol degradation.
The Fenton process has been considered as one of the most promising advanced oxidation processes (AOPs) for the treatment of persistent organic pollutants (POPs). Herein, engineered nanoscale schwertmannite (nano–SCH) were fabricated from a PVP (polyvinylpyrrolidone) assisted room–temperature synthesis. The as–prepared well–dispersed nano–SCH materials were further studied as Fenton–like catalysts for 4–nitrophenol (4–NP) degradation in the presence of H2O2. Results showed that the optimized nano–SCH–0.125 was able to degrade 91.0% of 4–NP in 60 min at 298 K, thanks to the nanoscale and hierarchical surface structures that provided abundant reactive sites at solid/solution interfaces. Moreover, mechanism study indicated that •OH radicals were the main reactive species responsible for the excellent 4–NP degradation performances during the Fenton–like processes. This work thus provides a viable pathway to engineer nanoscale materials with enhanced catalytic properties in oxidative degradation of environmental pollutants.
A conjugated microporous polymer (CMP) material was designed with pore function of cyano and pyridyl groups that act as potential binding sites for Ag+ ion capture. Ultrafine silver nanoparticles ...(less than 5 nm) were successfully supported on the predesigned CMP material to afford Ag0@CMP composite materials by means of a simple liquid impregnation and light-induced reduction method. Spherical Ag0 nanoparticles with a statistical mean diameter of ca. 3.9 nm were observed and characterized by scanning electron microscopy and transmission electron microscopy. The Ag0@CMP composite materials were consequently exploited as high-performance nanocatalysts for the reduction of nitrophenols, a family of priority pollutants, at various temperatures and ambient pressure. Moreover, the composite nanocatalysts feature convenient recovery and excellent reusability. This work presents an efficient platform to achieve ultrafine metal nanoparticles immobilized on porous supports with predominant catalytic properties by virtue of the structural design and spatial confinement effect available for conjugated microporous polymers.
In view of the increasing concerns for environmental problems caused by the widespread use of antibiotics, there is an urgent demand to develop effective technologies for antibiotics removal from ...pharmaceutical wastewater. For this purpose, photocatalysis has been developed as an important advanced oxidation technology possessing remarkable prospective, and thus, the semiconductor photocatalysts are currently attracting unprecedented research attention. Herein, we report the fabrication of composite materials based on nitrogen-doped carbons and cadmium sulfide semiconductors (CdS/NC–T ) derived solely from cadmium metal–organic frameworks (Cd–MOF) through a facile in situ carbonization method, as well as their application as viable photocatalysts toward tetracycline degradation under visible irradiation. It was revealed that cadmium and sulfur species in Cd–MOF precursors assembled to form CdS nanoparticles (NPs), which were deposited simultaneously on nitrogen-doped carbon scaffolds to afford CdS/NC–T composites during carbonization processes. PXRD and TEM studies on as-prepared CdS/NC–T materials indicated the formation of crystalline hexagonal (Wurtzite) CdS NPs on carbonaceous supports. These CdS/NC–T composites were further studied for photocatalytic tetracycline degradation in aqueous solutions under visible irradiation, among which CdS/NC–500 exhibited the highest TC degradation efficiency of ca. 83% within 1 h. It was found that the photocatalytic performance of CdS/NC–T depended largely on carbonization temperature, which suggested great potentials of the proposed synthetic pathway in engineering of new visible-light-driven photocatalysts.
Novel magnetic Ag@RF@Fe3O4 core-satellite (MCS) nanocomposites were prepared through in situ photoreduction upon bridging Fe(III) and Ag+ via hydroxyl groups in resorcinol formaldehyde (RF) resin by ...virtue of the coordination effect. The catalytic activity of MCS nanocomposites was evaluated based on catalytic 4-nitrophenol (4-NP) reduction with NaBH4 as the reducing agent. It was noteworthy that the MCS-3 was beneficial to obtain a superior reaction rate constant of 2.27 min−1 and a TOF up to 72.7 h−1. Moreover, the MCS could be easily recovered by applying an external magnetic field and was reused for five times without significantly decrease in catalytic activity. Kinetic and thermodynamic study revealed that catalytic 4-NP reduction using MCS nanocatalysts obeyed the Langmuir-Hinshelwood mechanism and was controlled by the diffusion rate of substrates. Overall, the immobilization of ultra-fine Ag nanoparticles and the extremely negative potentials around MCS nanocomposites, which were effective for the diffusion of reactants, synergistically accelerated the catalytic reduction reactions.
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•Ag NPs immobilized onto magnetic core-satellite nanocomposites were prepared.•The nanocatalyst showed a superior rate constant of 2.27 min−1 in 4-NP reduction.•The nanocatalyst exhibited considerable activity towards nitrophenol derivatives.
Maleimide-thiol reactions are widely used to produce protein-polymer conjugates for therapeutics. However, maleimide-thiol adducts are unstable in vivo or in the presence of thiol-containing ...compounds because of the elimination of the thiosuccinimide linkage through a retro-Michael reaction or thiol exchange. Here, using single-molecule force spectroscopy, we show that applying an appropriate stretching force to the thiosuccinimide linkage can considerably stabilize the maleimide-thiol adducts, in effect using conventional mechanochemistry of force-accelerated bond dissociation to unconventionally stabilize an adjacent bond. Single-molecule kinetic analysis and bulk structural characterizations suggest that hydrolysis of the succinimide ring is dominant over the retro-Michael reaction through a force-dependent kinetic control mechanism, and this leads to a product that is resistant to elimination. This unconventional mechanochemical approach enabled us to produce stable polymer-protein conjugates by simply applying a mechanical force to the maleimide-thiol adducts through mild ultrasonication. Our results demonstrate the great potential of mechanical force for stimulating important productive chemical transformations.
The dorsal raphe nucleus (DRN) is an important nucleus in pain regulation. However, the underlying neural pathway and the function of specific cell types remain unclear. Here, we report a previously ...unrecognized ascending facilitation pathway, the DRN to the mesoaccumbal dopamine (DA) circuit, for regulating pain. Chronic pain increased the activity of DRN glutamatergic, but not serotonergic, neurons projecting to the ventral tegmental area (VTA) (DRN
-VTA) in male mice. The optogenetic activation of DRN
-VTA circuit induced a pain-like response in naive male mice, and its inhibition produced an analgesic effect in male mice with neuropathic pain. Furthermore, we discovered that DRN ascending pathway regulated pain through strengthened excitatory transmission onto the VTA DA neurons projecting to the ventral part of nucleus accumbens medial shell (vNAcMed), thereby activated the mesoaccumbal DA neurons. Correspondingly, optogenetic manipulation of this three-node pathway bilaterally regulated pain behaviors. These findings identified a DRN ascending excitatory pathway that is crucial for pain sensory processing, which can potentially be exploited toward targeting pain disorders.
Abstract
Gram-positive bacteria can resist large mechanical perturbations during their invasion and colonization by secreting various surface proteins with intramolecular isopeptide or ester bonds. ...Compared to isopeptide bonds, ester bonds are prone to hydrolysis. It remains elusive whether ester bonds can completely block mechanical extension similarly to isopeptide bonds, or whether ester bonds dissipate mechanical energy by bond rupture. Here, we show that an ester-bond containing stalk domain of Cpe0147 is inextensible even at forces > 2 nN. The ester bond locks the structure to a partially unfolded conformation, in which the ester bond remains largely water inaccessible. This allows the ester bond to withstand considerable mechanical forces and in turn prevent complete protein unfolding. However, the protecting effect might be reduced at non-physiological basic pHs or low calcium concentrations due to destabilizing the protein structures. Inspired by this design principle, we engineer a disulfide mutant resistant to mechanical unfolding under reducing conditions.
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