Design Principle of Molybdenum-Based Metal Nitrides for Lattice Nitrogen-Mediated Ammonia Production.

Chemical looping ammonia synthesis (CLAS) is a promising technology for reducing the high energy consumption of the conventional ammonia synthesis process. However, the comprehensive understanding of reaction mechanisms and rational design of novel nitrogen carriers has not been achieved due to the high complexity of catalyst structures and the unrevealed relationship between electronic structure and intrinsic activity. Herein, we propose a multistage strategy to establish the connection between catalyst intrinsic activity and microscopic electronic structure fingerprints using density functional theory computational energetics as bridges and apply it to the rational design of metal nitride catalysts for lattice nitrogen-mediated ammonia production. Molybdenum-based nitride catalysts with well-defined structures are employed as prototypes to elucidate the decoupled effects of electronic and geometrical features. The electron-transfer and spin polarization characteristics of the magnetic metals are constructed as descriptors to disclose the atomic-scale causes of intrinsic activity. Based on this design strategy, it is demonstrated that Ni3Mo3N catalysts possess the highest lattice nitrogen-mediated ammonia synthesis activity. This work reveals the structure-activity relationship of metal nitrides for CLAS and provides a multistage perspective on catalyst rational design.

High-sensitivity piezoresistive sensors based on cellulose handsheets using origami-inspired corrugated structures.

Cellulose-based composites have attracted significant attention in the fabrication and advancement of wearable devices due to their sustainable, degradable, and cost-effective properties. However, achieving a cellulosic sensor with reliable sensory feedback remains challenging owing to the deficiency in reversible microstructures during response processes. In this study, we developed a piezoresistive sensor consisting of nearly pure cellulose handsheets using origami-inspired corrugated structures to achieve durable and sensitive piezoresistive responses. Multi-walled carbon nanotubes (MWCNTs) were used as conducting agents. With the addition of 7 wt% MWCNTs, 36.27 % of the cellulose fiber surface was covered and the conductivity of cellulose handsheets was increased to 8.7 S/m. The obtained conductive cellulose handsheets were transformed into corrugated structures and integrated orthogonally to construct the piezoresistive sensors with reversible electrical paths for electrons. The restorable corrugated structure endowed the sensors with a wide workable pressure range (0-10 kPa), high sensitivity (6.09 kPa-1 in a range of 0-0.92 kPa), fast response time (<280 ms), and good durability (>1000 cycles). Furthermore, the practical applications of the proposed sensors as wearable devices were demonstrated through phonation, real-time sports monitoring, and step pressure tests.

Observing Discrete Blocking Events at a Polarized Micro- or Submicro-Liquid/Liquid Interface.

Single-entity collisional electrochemistry (SECE), a subfield of single-entity electrochemistry, enables directly characterizing entities and particles in the electrolyte solution at the single-entity resolution. Blockade SECE at the traditional solid ultramicroelectrode (UME)/electrolyte interface suffers from a limitation: only redox-inactive particles can be studied. The wide application of the classical Coulter counter is restricted by the rapid translocation of entities through the orifice, which results in a remarkable proportion of undetected signals. In response, the blocking effect of single charged conductive or insulating nanoparticles (NPs) at low concentrations for ion transfer (IT) at a miniaturized polarized liquid/liquid interface was successfully observed. Since the particles are adsorbed at the liquid/liquid interface, our method also solves the problem of the Coulter counter having a too-fast orifice translocation rate. The decreasing quantal staircase/step current transients are from landings (controlled by electromigration) of either conductive or insulating NPs onto the interface. This interfacial NP assembly shields the IT flux. The size of each NP can be calculated by the step height. The particle size measured by dynamic light scattering (DLS) is used for comparison with that calculated from electrochemical blocking events, which is in fairly good agreement. In short, the blocking effect of IT by single entities at micro- or submicro-liquid/liquid interface has been proven experimentally and is of great reference in single-entity detection.

Synergistic interplay between ABA-generating bacteria and biochar in the reduction of heavy metal accumulation in radish, pakchoi, and tomato.

Heavy metal (HM) contamination is an environmental concern that threatens the agricultural product safety and human health. To address this concern, we developed a novel strategy involving the synergistic application of Azospirillum brasilense, a growth-promoting rhizobacterium which produces abscisic acid (ABA), and biochar to minimize HM accumulation in the edible parts of vegetable crops. Compared to A. brasilense or biochar alone, the concentrations of Cd, Ni, Pb, and Zn in radish (Raphanus sativus L.), pakchoi (Brassica chinensis L.), and tomato (Lycopersicon esculentum L.) decreased by 18-63% and 14-56%, respectively. Additionally, the synergistic treatment led to a 14-63% decrease in the bioconcentration factor. The biomass of the edible parts of the three crops increased by 65-278% after synergistic treatment, surpassing the effects of single treatments. Furthermore, the synergistic application enhanced the SPAD values by 1-45% compared to single treatments. The MDA concentrations in stressed plants decreased by 16-39% with the bacteria-biochar co-treatment compared to single treatments. Co-treatment also resulted in increased soluble protein and sugar concentrations by 8-174%, and improvements in flavonoids, total phenols, ascorbic acid, and DPPH levels by 2-50%. Pearson correlation analysis and structural equation modeling revealed that the synergistic effect was attributed to the enhanced growth of A. brasilense facilitated by biochar and the improved availability of HMs in soils. Notably, although ABA concentrations were not as high as those achieved with A. brasilense alone, they were maintained at relatively high levels. Overall, the synergistic application of A. brasilense-biochar might have remarkable potential for reducing the accumulation of HMs while promoting growth and improving nutritional and antioxidant qualities in tuberous, leafy, and fruit crops.

Different pathways for exogenous ABA-mediated down-regulation of cadmium accumulation in plants under different iron supplies.

Exogenous abscisic acid (ABA) could inhibit cadmium (Cd) accumulation in plants; however, its performance in an uneven iron (Fe) background remains unknown. Here, we found that the inhibitory effects of ABA on Cd accumulation in plants were optimal under nonlimiting Fe availability (25 and 50 µM), causing a reduction of 25-50 %, whereas only a 0-29 % decrease was observed in a Fe-free or -deficient (5 µM) medium. Although ABA significantly inhibited the expression of IRT1 under different Fe supplies, the inhibitory effects of ABA on Cd accumulation were lower (or absent) in irt1-mutants than in wild-type plants growing under nonlimiting Fe availability, whereas no significant difference was found under Fe deficiency. The mechanisms by which ABA reduces Cd accumulation under different Fe environments may differ. Furthermore, under Fe sufficiency, ABA increased Fe levels of root apoplasts by 91 % without changing the activity level of root ferric reductase (FCR). In contrast, ABA resulted in a 17 % decrease in Fe concentration in apoplasts and a 37 % decrease in FCR activity under Fe-deficient conditions. Thus, under Fe sufficiency, plants may show a reduced accumulation of Cd by accumulating more Fe in the apoplasts, which in turn inhibits the expression of IRT1. However, plants are more prone to redirect apoplastic Fe to prevent Cd accumulation under Fe deficiency. The different mechanisms of inhibition of Cd accumulation by ABA under different Fe supplies revealed in this study may provide guidelines for the precise regulation of Cd accumulation in crops via ABA-based strategies.

Abscisic acid-catabolizing bacteria: A useful tool for enhancing phytoremediation.

Bacteria-facilitated phytoextraction has been gaining recognition for the phytoremediation of heavy metal (HM)-contaminated soils. Nevertheless, it remains unclear whether catabolizing abscisic acid (ABA) in hyperaccumulating plants via rhizobacteria could facilitate HM phytoextraction. In this study, inoculation with the ABA-catabolizing bacterium, Rhodococcus qingshengii, increased HM (Cd, Zn, Pb, and Cu) concentrations in the shoots of hyperaccumulators Vetiveria zizanioides, Brassica juncea, Lolium perenne L., Solanum nigrum L., and Sedum alfredii Hance grown in mildly and severely contaminated soils by 28.8%-331.3%, 8.5%-393.4%, 21.2%-222.5%, 14.7%-115.5%, and 28.3%-174.2%, respectively, compared with non-inoculated plants. The fresh biomass of these hyperaccumulators was elevated by 16.5%-94.4%, compared to that of the bacteria-free control. Phytoremediation potential indices, including bioconcentration and translocation factors, also revealed that the bacteria markedly boosted the phytoextraction efficacy from soil. Furthermore, principal component analysis (PCA) suggested that the effects of bacteria on the concentrations of Cd and Zn in hyperaccumulators were significantly correlated with ABA metabolism, but not with Pb and Cu. Combined with the synergistic effects on plant biomass, the bacteria also improved the phytoextraction of Pb and Cu in hyperaccumulators. Overall, the application of microorganism-assisted remediation based on ABA-catabolizing bacteria might be an alternative strategy for enhancing phytoremediation efficiency in HM-contaminated soils.

Polymeric Iron Chelators Enhancing Pro-Oxidant Antitumor Efficacy of Vitamin C by Inhibiting the Extracellular Fenton Reaction.

Intravenously injected high-dose vitamin C (VC) induces extracellular H2O2, which can penetrate into the tumor cells and suppress tumor growth. However, extracellular labile iron ions in the tumor decompose H2O2 via the Fenton reaction, limiting the therapeutic effect. In this regard, we recently developed a polymeric iron chelator that can inactivate the intratumoral labile iron ions. Here, we examined the effect of our polymeric iron chelator on the high-dose VC therapy in in vitro and in vivo. In the in vitro study, the polymeric iron chelator could inactivate the extracellular labile iron ions and prevent the unfavorable decomposition of VC-induced H2O2, augmenting pro-oxidative damage to DNA and inducing apoptosis in cultured cancer cells. Even in the in vivo study, the polymeric iron chelator significantly improved the antitumor effect of VC in subcutaneous DLD-1 and CT26 tumors in mice, while conventional iron chelators could not. This work indicates the importance of modulating tumor-associated iron ions in the high-dose VC therapy and should contribute to a better understanding of its mechanism.

Ultrahigh-Resolution, Label-Free Hyperlens Imaging in the Mid-IR.

The hyperbolic phonon polaritons supported in hexagonal boron nitride (hBN) with long scattering lifetimes are advantageous for applications such as super-resolution imaging via hyperlensing. Yet, hyperlens imaging is challenging for distinguishing individual and closely spaced objects and for correlating the complicated hyperlens fields with the structure of an unknown object underneath. Here, we make significant strides to overcome each of these challenges. First, we demonstrate that monoisotopic h11BN provides significant improvements in spatial resolution, experimentally resolving structures as small as 44 nm and those with sub 25 nm spacings at 6.76 µm free-space wavelength. We also present an image reconstruction algorithm that provides a structurally accurate, visual representation of the embedded objects from the complex hyperlens field. Further, we offer additional insights into optimizing hyperlens performance on the basis of material properties, with an eye toward realizing far-field imaging modalities. Thus, our results significantly advance label-free, high-resolution, spectrally selective hyperlens imaging and image reconstruction methodologies.

A Multi-Objective Multi-Label Feature Selection Algorithm Based on Shapley Value.

Multi-label learning is dedicated to learning functions so that each sample is labeled with a true label set. With the increase of data knowledge, the feature dimensionality is increasing. However, high-dimensional information may contain noisy data, making the process of multi-label learning difficult. Feature selection is a technical approach that can effectively reduce the data dimension. In the study of feature selection, the multi-objective optimization algorithm has shown an excellent global optimization performance. The Pareto relationship can handle contradictory objectives in the multi-objective problem well. Therefore, a Shapley value-fused feature selection algorithm for multi-label learning (SHAPFS-ML) is proposed. The method takes multi-label criteria as the optimization objectives and the proposed crossover and mutation operators based on Shapley value are conducive to identifying relevant, redundant and irrelevant features. The comparison of experimental results on real-world datasets reveals that SHAPFS-ML is an effective feature selection method for multi-label classification, which can reduce the classification algorithm's computational complexity and improve the classification accuracy.

Potential urinary monitoring of the enhanced permeability and retention effect using MMP-2-responsive poly(ethylene glycol) derivatives.

The enhanced permeability and retention (EPR) effect is fundamental to tumor-targeted drug delivery using nanoparticles. However, recent studies reported heterogeneity of the EPR effect, and companion diagnostics are considered to be key to predicting and optimizing the benefits of the EPR effect. Here, as a new material to simply endow the function of companion diagnostics to nanoparticles, we designed a poly(ethylene glycol) (PEG) derivative conjugated with low molecular fluorescent dye through synthetic substrate linker that can be cleaved in response to MMP-2, which is overexpressed in tumor extracellular matrix. Upon tumor accumulation, the low molecular fluorescent dye is released from the PEG and quickly excreted to urine, thereby reporting its tumor accumulation level as a fluorescent signal in the urine. In this study, this urinary reporter was conjugated with albumin, and the functionalized albumin exhibited efficient accumulation in various tumors. Importantly, the functionalized albumin exhibited significantly higher excretion of the fluorescent dye in the urine in mice with tumors compared with those without tumors. The PEG derivatives proposed in this study may be a promising tool to predict the EPR effect in individual cancer patients.

Hydrogel-Based Sensor Networks: Compositions, Properties, and Applications-A Review.

Hydrogels are three-dimensional porous polymeric networks prepared by physical or chemical cross-linking of hydrophilic molecules, which can be made into smart materials through judicious chemical modifications to recognize external stimuli; more specifically, this can be accomplished by the integration with stimuli-responsive polymers or sensing molecules that has drawn considerable attention in their possible roles as sensors and diagnostic tools. They can be tailored in different structures and integrated into systems, depending on their chemical and physical structure, sensitivity to the external stimuli and biocompatibility. A panoramic overview of the sensing advances in the field of hydrogels over the past several decades focusing on a variety protocols of hydrogel preparations is provided, with a major focus on natural polymers. The modifications of hydrogel composites by incorporating inorganic nanoparticles and organic polymeric compounds for sensor applications and their mechanisms are also discussed.

Highly tunable bioadhesion and optics of 3D printable PNIPAm/cellulose nanofibrils hydrogels.

A hybrid poly(N-isopropylacrylamide) (PNIPAm)/cellulose nanofibrils (CNFs) hydrogel composite was fabricated by inverted stereolithography 3D printing to provide a new platform for regulating lower critical solution temperature (LCST) properties and thus tuning optical and bioadhesive properties. The phenomena of interest in the as-printed PNIPAm/CNF hydrogels may be attributed to the fiber-reinforced composite system between crosslinked PNIPAm and CNFs. The optical tunability was found to be correlated to the micro/nano structures of the PNIPAm/CNF hydrogel films. It was found that PNIPAm/CNF hydrogels exhibit switchable bioadhesivity to bacteria in response to CNF distribution in the hydrogels. After 2.0 wt% CNF was incorporated, it was found that a remarkable 8°C reduction of the LCST was achieved relative to PNIPAm hydrogel crosslinked by TEGDMA without CNF. The prepared PNIPAm/CNF hydrogels possessed highly reversible optical, bioadhesion, and thermal performance, making them suitable to be used as durable temperature-sensitive sensors and functional biomedical devices.

Highly conductive carbon nanotubes and flexible cellulose nanofibers composite membranes with semi-interpenetrating networks structure.

Highly conductive multi-walled carbon nanotubes (MWCNTs) and flexible cellulose nanofibers (CNF) membranes with semi-interpenetrating networks structure were fabricated using the typical paper-making method, which was simple and cost-effective. The Scanning electron microscope (SEM), Fourier-transform infrared (FT-IR), and thermal gravimetric analysis (TGA) were used to estimate the morphology, chemical structure, and thermal stability of the membranes. The mechanical, optical, and electrical properties of the membranes were characterized with a uniaxial tensile testing machine, ultraviolet visible spectroscope, and digital multimeter, respectively. The results indicated that the membranes containing 10 wt% of MWCNTs showed a high conductivity value of 37.6 S/m, and the sheet resistances of the membranes were stable at different bending states. Furthermore, we demonstrated the electrical features of membrane-based capacitive pressure sensors based on CNF/MWCNTs. The proposed method for fabricating CNF/MWCNTs membranes can simplify the production process and have great practical potential in various electronics applications such as touch screens.

Unique thermo-responsivity and tunable optical performance of poly(N-isopropylacrylamide)-cellulose nanocrystal hydrogel films.

A hybrid materials system to modulate lower critical solution temperature (LCST) and moisture content for thermo-responsivity and optical tunability was strategically developed by incorporating cellulose nanocrystals (CNCs) into a poly(N-isopropylacrylamide) (PNIPAm) hydrogel matrix. The PNIPAm/CNC hydrogel films exhibit tunable optical properties and wavelength bandpass selectivity as characterized by PROBE Spectroscopy and Dynamic Light Scattering (DLS). Importantly, the micro/nano structures of the PNIPAm/CNC hydrogel films were completely different when dried below and above the LCST. Below the LCST, PNIPAm/CNC hydrogel films exhibit transparency or semi-transparency due to the uniform bonding of hydrophilic PNIPAm and CNC through hydrogen bonds. Above the LCST, the hydrogel films engage in both hydrophobic PNIPAm and hydrophilic CNC interactions due to changes in PNIPAm conformation which lead to light scattering effects and hence opacity. Furthermore, the incorporation of CNC induces a ∼ 15 °C reduction of the LCST relative to pure PNIPAm hydrogel films.

Removal of Pb(II) from aqueous solutions by adsorption on magnetic bentonite.

Bentonite is a porous clay material that shows good performance for adsorbing heavy metals and other pollutants for wastewater remediation. In our previous study, magnetic bentonite (M-B) was prepared to solve the separation problem and improve the operability. In this study, we investigated the influence of various parameters on the Pb(II) adsorption of M-B, and it showed effective performance. About 98.9% adsorption removal rate was achieved within 90 min at adsorbent dose of 10 g/L for initial Pb(II) concentration of 200 mg/L at 40 °C and pH 5. The adsorption kinetic fit well by the pseudo-second-order model, and also followed the intra-particle diffusion model up to 90 min. Moreover, adsorption data were successfully reproduced by the Langmuir isotherm; the maximum adsorption capacity was calculated as 80.40 mg/g. The mechanism of interaction between Pb(II) ions and M-B was ionic exchange, surface complexation, and electro-static interactions. Thermodynamics study indicated that the reaction of Pb(II) adsorption on M-B was endothermic and spontaneous; increasing the temperature promoted adsorption. This study was expected to provide a reference and theoretical basis for the treatment of Pb-containing wastewater using bentonite materials.

Resourceful treatment of alcohol distillery wastewater by pulsed discharge.

Resourceful treatment of alcohol distillery wastewater by pulsed discharge in liquid (PDL) was first studied in this work. The biodegradability of alcohol wastewater can be effectively improved and chemical oxygen demand (COD) removal attained over 40% within 15min PDL treatment. Hydrogen produced from the treating processes was emphatically analyzed. The flow rate, and yield of hydrogen achieved were 80mL/min, 146mL/g COD removed within 30min respectively, which were much better than existing technologies. Meanwhile, the mechanism of hydrogen production from alcohol distillery wastewater by PDL was presented in this work indicating that different region in reactor has different mechanism. In discharge channel, high-energy electrons and resultant free radicals played a leading role. Far away from discharge channel, the neutral particles with strong oxidizing were more important. This work can be a good guidance for both treatment of refractory wastewater and mechanism of hydrogen production by plasma reforming.

[Temporary ectopic implantation of amputated fingers and dorsalis pedis flaps for thumb reconstruction and skin defect repair of hands].

OBJECTIVE: To investigate the feasibility of temporary ectopic implantation of amputated fingers and dorsalis pedis flaps for thumb reconstruction and skin defect repair of the hand. METHODS: Between February 2006 and February 2012, 9 patients with thumb amputation having no replanted condition were treated. There were 7 males and 2 females with an average age of 35 years (range, 20-45 years). The injury causes included explosive injury in 1 case, puncher injury in 1 case, stiring machine injury in 1 case, gear injury in 3 cases, and heavy pound injury in 3 cases. At 2-5 hours after injury, one-stage temporary ectopic implantation of amputated finger to foot was performed. After debridement, thumb defect was rated as degree III in 1 case, as degree IV in 3 cases, and as degree V in 5 cases. When amputated fingers survived completely after 1-4 months, the amputated finger was replanted to its anatomic position, skin defect was repaired with dorsalis pedis flap. The area of skin defect ranged from 5 cm x 4 cm to 7 cm x 6 cm. The area of flaps ranged from 6 cm x 5 cm to 8 cm x 7 cm. The donor site was repaired by the skin grafting. RESULTS: Arterial crisis occurred in 1 case after 1 day of one-stage operation, and was cured after vascular exploration, and the amputated fingers survived in the others. The reconstructed thumbs and flaps survived after two-stage operation, and the skin graft at donor site survived. The patients were followed up 1-4 years (mean, 2.8 years). The reconstructed thumbs had good appearance and satisfactory opposition and finger-to-finger functions. According to the standard functional evaluation issued by Hand Surgery Association of Chinese Medical Association, the scores of survival fingers were 73-91 (mean, 84); the results were excellent in 7 cases and good in 2 cases with an excellent and good rate of 100%. CONCLUSION: Temporary ectopic implantation of amputated finger to foot combined with dorsalis pedis flap can be used to reconstruct thumb and repair skin defect of the hand.