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With the rapid development of cloud computing technology, how to achieve secure access to cloud data has become a current research hotspot. Attribute-based encryption technology provides the feasibility to achieve the above goal. However, most of the existing solutions have high computational and trust costs. Furthermore, the fairness of access authorization and the security of data search can be difficult to guarantee. To address these issues, we propose a novel access control scheme based on blockchain and attribute-based searchable encryption in cloud environment. The proposed scheme achieves fine-grained access control with low computation consumption by implementing proxy encryption and decryption, while supporting policy hiding and attribute revocation. The encrypted file is stored in the IPFS and the metadata ciphertext is stored on the blockchain, which ensures data integrity and confidentiality. Simultaneously, the scheme enables the secure search of ciphertext keyword in an open and transparent blockchain environment. Additionally, an audit contract is designed to constrain user access behavior to dynamically manage access authorization. Security analysis proves that our scheme is resistant to chosen-plaintext attacks and keyword-guessing attacks. Theoretical analysis and experimental results show that our scheme has high computational and storage efficiency, which is more advantageous than other schemes.

Background The prognosis of B-cell acute lymphoblastic leukemia (B-ALL) has improved significantly with current first-line therapy, although the recurrence of B-ALL is still a problem. Toll-like receptor 9 (TLR9) agonists have shown good safety and efficiency as immune adjuvants. Apart from their immune regulatory effect, the direct effect of TLR9 agonists on cancer cells with TLR9 expression cannot be ignored. However, the direct effect of TLR9 agonists on B-ALL remains unknown. Methods We discussed the relationship between TLR9 expression and the clinical characteristics of B-ALL and explored whether CpG 685 exerts direct apoptotic effect on B-ALL without inhibiting normal B-cell function. By using western blot, co-immunoprecipitation, immunofluorescence co-localization, and chromatin immunoprecipitation, we explored the mechanism of the apoptosis-inducing effect of CpG 685 in treating B-ALL cells. By exploring the mechanism of CpG 685 on B-ALL, the predictive biomarkers of the efficacy of CpG 685 in treating B-ALL were explored. These efficiencies were also confirmed in mouse model as well as clinical samples. Results High expression of TLR9 in B-ALL patients showed good prognosis. C-MYC-induced BAX activation was the key to the effect of CpG oligodeoxynucleotides against B-ALL. C-MYC overexpression promoted P53 stabilization, enhanced Bcl-2 associated X-protein (BAX) activation, and mediated transcription of the BAX gene. Moreover, combination therapy using CpG 685 and imatinib, a BCR-ABL kinase inhibitor, could reverse resistance to CpG 685 or imatinib alone by promoting BAX activation and overcoming BCR-ABL1-independent PI3K/AKT activation. Conclusion TLR9 is not only a prognostic biomarker but also a potential target for B-ALL therapy. CpG 685 monotherapy might be applicable to Ph− B-ALL patients with C-MYC overexpression and without BAX deletion. CpG 685 may also serve as an effective combinational therapy against Ph+ B-ALL.

Given the critical role of SCF E3 ligases in autophagy by modulating the protein stability of various autophagic components, the activity of SCF should be tightly controlled to maintain the autophagic flux. We here showed that Numb, a multifunctional adaptor protein, increased the protein abundance of DEPTOR, which is an inhibitor of mTORC1, leading to increased autophagy flux. In vitro ubiquitination assay demonstrated that Numb inhibited SCF(β-TrCP2) mediated ubiquitination of DEPTOR. Mechanistically, Numb interrupted the interaction between β-TrCP2 and SKP1 by directly binding with SKP1. In the presence of wild type β-TrCP2, Numb overexpression inhibited DEPTOR degradation. Whereas, in the presence of the mutant β-TrCP2 which lacks the F-box domain, Numb overexpression did not affect the protein abundance of DEPTOR. In mouse model of renal fibrosis induced by unilateral ureteral obstruction, the expression of Numb was significantly increased. Consistently, the upregulation of Numb was observed in renal fibrotic lesions of chronic kidney disease patients. Specifically depleting Numb in proximal renal tubules decreased the protein abundance of DEPTOR, attenuated autophagy in fibrotic lesions and protected the kidney from development of renal fibrosis in vivo. Taken together, both in vitro and in vivo data indicated that Numb functions as a novel regulator to fine tuning the activity of SCF(β-TrCP2) in modulating autophagy.

Sirt6 has been implicated as a key regulator in aging-related diseases, including osteoarthritis. However, its functional role and molecular mechanism in chondrocyte senescence and osteoarthritis pathophysiology remain largely undefined. Here we show that Sirt6 deficiency exaggerates chondrocyte senescence and osteoarthritis progression, whereas intra-articular injection of adenovirus-Sirt6 markedly attenuates surgical destabilization of medial meniscus-induced osteoarthritis. Mechanistically, Sirt6 can directly interact with STAT5 and deacetylate STAT5, thus inhibiting the IL-15/JAK3-induced STAT5 translocation from cytoplasm to nucleus, which inactivates IL-15/JAK3/STAT5 signaling. Mass spectrometry revealed that Sirt6 deacetylated conserved lysine 163 on STAT5. Mutation of lysine 163 to arginine in STAT5 abolished the regulatory effect of Sirt6. In vivo, specific ablation of Sirt6 in chondrocytes exacerbated osteoarthritis. Pharmacological activation of Sirt6 substantially alleviated chondrocyte senescence. Taken together, Sirt6 attenuates chondrocyte senescence by inhibiting IL-15/JAK3/STAT5 signaling. Targeting Sirt6 represents a promising new approach for osteoarthritis.

To investigate the influence of epileptogenic cortex (Rolandic areas) with executive functions in Rolandic epilepsy using structural covariance analysis of structural magnetic resonance imaging (MRI). Structural MRI data of drug-naive patients with Rolandic epilepsy (n = 70) and typically developing children as healthy controls (n = 83) were analyzed using voxel-based morphometry. Gray matter volumes in the patients were compared with those of healthy controls, and were further correlated with epilepsy duration and cognitive score of executive function, respectively. By applying Granger causal analysis to the sequenced morphometric data according to disease progression information, causal network of structural covariance was constructed to assess the causal influence of structural changes from Rolandic cortices to the regions engaging executive function in the patients. Compared with healthy controls, epilepsy patients showed increased gray matter volume in the Rolandic regions, and also the regions engaging in executive function. Covariance network analyses showed that along with disease progression, the Rolandic regions imposed positive causal influence on the regions engaging in executive function. In the patients with Rolandic epilepsy, epileptogenic regions have causal influence on the structural changes in the regions of executive function, implicating damaging effects of Rolandic epilepsy on human brain.

Metal catalysts play an important role in the catalytic electrochemical processes and optimization of their performance is usually achieved through alloying with other metal atoms. Doping with interstitial hydrogen atoms is a special but effective way to regulate the electronic structure of host catalysts. Herein we demonstrate the intermixing of Pd and Rh atoms during the hydrogen-doping process of Pd@Rh core-shell nanocubes, forming an alloyed surface in Pd@Rh-H. The catalysts show enhanced performance in electrocatalytic methanol oxidation, as compared to commercial Pt/C and are even better than PdH@Rh core-shell nanocubes. The small structural differences between the two hydride catalysts are revealed by X-ray electron spectroscopy and pair distribution function analysis of electron diffraction. The theoretical calculation results show that Rh in Pd@Rh-H contains more negative charges than Rh in PdH@Rh, indicating more effective charge transfer in Pd@Rh-H. The d-band center (ed) of the Rh site in Pd@Rh-H shifts up, and the synergy between Rh and Pd optimizes the binding energy of CO and OH, inducing preferential catalytic activity. Our work provides guidance for the synthesis of high-performance catalysts by doping with interstitial atoms, which may provide a new strategy to fine-tune the electronic structure of other bimetallic nanoparticles.

The mechanisms underlying fibrogenic responses after injury are not well understood. Epithelial cell cycle arrest in G2/M after injury is a key checkpoint for determining wound-healing leading to either normal cell proliferation or fibrosis. Here, we identify a kidney- and liver-enriched circular RNA, circBNC2, which is abundantly expressed in normal renal tubular cells and hepatocytes but significantly downregulated after acute ischemic or toxic insult. Loss of circBNC2 is at least partially mediated by upregulation of DHX9. Gain- and loss-of-function studies, both in vitro and in vivo, demonstrate that circBNC2 acts as a negative regulator of cell G2/M arrest by encoding a protein that promotes formation of CDK1/cyclin B1 complexes. Restoring circBNC2 in experimentally-induced male mouse models of fibrotic kidney and liver, decreases G2/M arrested cell numbers with secretion of fibrotic factors, thereby mitigating extracellular matrix deposition and fibrosis. Decreased expression of circBNC2 and increased G2/M arrest of epithelial cells are recapitulated in human ischemic reperfusion injury (IRI)-induced chronic kidney disease and inflammation-induced liver fibrosis, highlighting the clinical relevance. These findings suggest that restoring circBNC2 might represent a potential strategy for therapeutic intervention in epithelial organ fibrosis.

Clusters of regularly interspaced short palindromic repeats (CRISPR)/Cas systems have a powerful ability to edit DNA and RNA targets. However, the need for a specific recognition site, protospacer adjacent motif (PAM), of the CRISPR/Cas system limits its application in gene editing. Some Argonaute (Ago) proteins have endonuclease functions under the guidance of 5′ phosphorylated or hydroxylated guide DNA (gDNA). The NgAgo protein might perform RNA gene editing at 37 °C, suggesting its application in mammalian cells; however, its mechanisms are unclear. In the present study, the target of NgAgo in RNA was confirmed in vitro and in vivo. Then, an in vitro RNA cleavage system was designed and the cleavage site was verified by sequencing. Furthermore, NgAgo and gDNA were transfected into cells to cleave an intracellular target sequence. We demonstrated targeted degradation of GFP, HCV, and AKR1B10 RNAs in a gDNA-dependent manner by NgAgo both in vitro and in vivo, but no effect on DNA was observed. Sequencing demonstrated that the cleavage sites are located at the 3′ of the target RNA which is recognized by 5′ sequence of the gDNA. These results confirmed that NgAgo–gDNA cleaves RNA not DNA. We observed that the cleavage site is located at the 3′ of the target RNA, which is a new finding that has not been reported in the past.

The investigation of earth-abundant electrocatalysts for efficient water electrolysis is of central importance in renewable energy system, which is currently impeded by the large overpotential of oxygen evolution reaction (OER). NiFe sulfides show promising OER activity but are troubled by their low intrinsic conductivities. Herein, we demonstrate the construction of the porous core-shell heterojunctions of FeNi3@(Fe,Ni)S2 with tunable shell thickness via the reduction of hierarchical NiFe(OH)x nanosheets followed by a partial sulfidization. The conductive FeNi3 core provides the highway for electron transport, and the (Fe,Ni)S2 shell offers the exposed surface for in situ generation of S-doped NiFe-oxyhydroxides with high intrinsic OER activity, which is supported by the combined experimental and theoretical studies. In addition, the porous hierarchical morphology favors the electrolyte access and O2 liberation. Consequently, the optimized catalyst achieves an excellent OER performance with a low overpotential of 288 mV at 100 mA·cm−2, a small Tafel slope of 48 mV·dec−1, and a high OER durability for at least 1,200 h at 200 mA·cm−2. This study provides an effective way to explore the advanced earth-abundant OER electrocatalysts by constructing the heterojunctions between metal and corresponding metal-compounds via the convenient post treatment, such as nitridation and sulfidization.

Although Rolandic epilepsy (RE) has been regarded as a brain developmental disorder, neuroimaging studies have not yet ascertained whether RE has brain developmental delay. This study employed deep learning–based neuroanatomic biomarker to measure the changed feature of “brain age” in RE. The study constructed a 3D-CNN brain age prediction model through 1155 cases of typically developing children’s morphometric brain MRI from open-source datasets and further applied to a local dataset of 167 RE patients and 107 typically developing children. The brain-predicted age difference was measured to quantitatively estimate brain age changes in RE and further investigated the relevancies with cognitive and clinical variables. The brain age estimation network model presented a good performance for brain age prediction in typically developing children. The children with RE showed a 0.45-year delay of brain age by contrast with typically developing children. Delayed brain age was associated with neuroanatomic changes in the Rolandic regions and also associated with cognitive dysfunction of attention. This study provided neuroimaging evidence to support the notion that RE has delayed brain development. • The children with Rolandic epilepsy showed imaging phenotypes of delayed brain development with increased GM volume and decreased WM volume in the Rolandic regions. • The children with Rolandic epilepsy had a 0.45-year delay of brain-predicted age by comparing with typically developing children, using 3D-CNN-based brain age prediction model. • The delayed brain age was associated with morphometric changes in the Rolandic regions and attentional deficit in Rolandic epilepsy.

Two-dimensional (2D) oxide can be continuously produced by bubbling oxygen into liquid metals and the harvesting of these oxide relies on the proper choice of dispersion solvents. The mass-production of ligand-free 2D materials from high melting-point metals will not be possible if the limited stability of the traditional dispersion solvents is not circumvented. Herein, liquid tin was used for the first time in the bubbling protocol and 2D tin oxide was obtained in molten salts. The nanosheets were studied with combined microscopic and spectroscopic techniques, and high-density grain boundaries was identified between the sub-5-nm nano-crystallites in the nanosheets. It gives rise to the high performance in electrocatalytic CO2 reduction reaction. Density-functional-theory based calculation was applied to achieve a deeper understanding of the relationship between the activity, selectivity, and the grain-boundary features. The molten-salt based protocol could be explored for the synthesis of a library of functional 2D oxides.

Increasing the energy density of supercapacitor without sacrificing its high power is an everlasting pursuit in energy storage. Using ionic liquid electrolyte with high operating voltage can increase the energy density but usually at the expense of power density due to the large ion size, low ionic conductivity and high viscosity. Herein we demonstrate a simultaneous increase of the energy and power densities with ionic liquid electrolyte (EMIMBF4) mainly by enlarging the ion-transfer micropore channels of the electrode material, i.e., the unique hierarchical carbon nanocages (hCNC). Boudouard reaction is adopted to tune the micropore size while remaining the hierarchical framework of hCNC. Meanwhile, the specific surface area, pore volume and conductivity are also increased under optimal activation temperature. Such a unique modification boosts the large-sized ion transfer, leading to the obvious decrease of equivalent series resistance and the dramatic increase of supercapacitive performance thereof. The optimized product exhibits an energy density up to 153.8 W h kg−1 at the power density of 1.8 kW kg−1, and maintains 54.0 W h kg−1 even at an ultrahigh power density of 480.1 kW kg−1. This study demonstrates an effective way to explore advanced electrode materials by the fine regulation of micropores and related properties.

The propagation of epigenetic information across cell divisions is crucial to the maintenance of cell identity. During DNA replication, both parental and newly synthesized histones are deposited onto the replicating DNA, where they assemble into nucleosomes. Parental histones bear a variety of post-translational modifications, which constitute crucial epigenetic information, and the pattern of parental and newly synthesized histone allocation is crucial for the determination and maintenance of cell fate in multicellular organisms. The DNA replication-coupled nucleosome assembly process is regulated by multitude of histone chaperones, and recent breakthroughs in next-generation sequencing and super-resolution imaging methods have provided novel insights into the underlying mechanisms. Here, we review recent findings concerning parental histone deposition onto replicating DNA strands and the segregation of these to symmetrically or asymmetrically dividing daughter cells. Furthermore, we discuss the role of the allocation patterns of parental and newly synthesized histones in the determination of cell fate.

A two-step hydrothermal method was used to synthesize Ag3PO4/MFe2O4 (M = Zn, Ni, Co) composites, which were characterized in detail and employed as the visible light-response catalysts in the removal of different organic pollutants such as methyl orange (MO), methylene blue (MB), tetracycline (TC), and levofloxacin (LVF). Compared with Ag3PO4/ZnFe2O4 and Ag3PO4/NiFe2O4, Ag3PO4/CoFe2O4 showed a higher photocatalytic performance because of its larger BET surface area and higher separation rate of charge carriers. After exposure to visible light for 40 min, the efficiency of MO degradation by optimized Ag3PO4/CoFe2O4 reached 94.8%, and the degradation efficiency of MB, TC, and LVF was 99.0%, 80.5%, and 75.5% after 60 min, respectively. Only MO was selected as the target contaminant, the visible light-driven catalytic activity of Ag3PO4/CoFe2O4 was slightly higher than that of pure Ag3PO4. The magnetic Ag3PO4/CoFe2O4 can be easily recovered and its recyclability was superior to bare Ag3PO4. Due to the narrow bandgap of MFe2O4 (M = Zn, Ni, Co), the photoexcited holes and electrons cannot transfer to the surface of MFe2O4 and participate in photocatalytic reaction, thus the reactive species generated in Ag3PO4/MFe2O4 suspension were derived only from irradiated Ag3PO4. This study provided a new insight into the photocatalytic mechanism of Ag3PO4/MFe2O4 (M = Zn, Ni, Co).

Development of efficient non-precious catalysts for seawater electrolysis is of great significance but challenging due to the sluggish kinetics of oxygen evolution reaction (OER) and the impairment of chlorine electrochemistry at anode. Herein, we report a heterostructure of Ni3S2 nanoarray with secondary Fe-Ni(OH)2 lamellar edges that exposes abundant active sites towards seawater oxidation. The resultant Fe-Ni(OH)2/Ni3S2 nanoarray works directly as a free-standing anodic electrode in alkaline artificial seawater. It only requires an overpotential of 269 mV to afford a current density of 10 mA·cm−2 and the Tafel slope is as low as 46 mV·dec−1. The 27-hour chronopotentiometry operated at high current density of 100 mA·cm−2 shows negligible deterioration, suggesting good stability of the Fe·Ni(OH)2/Ni3S2@NF electrode. Faraday efficiency for oxygen evolution is up to ∼ 95%, revealing decent selectivity of the catalyst in saline water. Such desirable catalytic performance could be benefitted from the introduction of Fe activator and the heterostructure that offers massive active and selective sites. The density functional theory (DFT) calculations indicate that the OER has lower theoretical overpotential than Cl2 evolution reaction in Fe sites, which is contrary to that of Ni sites. The experimental and theoretical study provides a strong support for the rational design of high-performance Fe-based electrodes for industrial seawater electrolysis.

Background Mice with humanized livers are important models to study drug toxicology testing, development of hepatitis virus treatments, and hepatocyte transplantation therapy. However, the huge difference between mouse and human in size and anatomy limited the application of humanized mice in investigating human diseases. Therefore, it is urgent to construct humanized livers in pigs to precisely investigate hepatocyte regeneration and human hepatocyte therapy. CRISPR/Cas9 system and somatic cell cloning technology were used to generate two pig models with FAH deficiency and exhibiting severe immunodeficiency (FAH/RAG1 and FAH/RAG1/IL2RG deficiency). Human primary hepatocytes were then successfully transplanted into the FG pig model and constructed two pigs with human liver. Results The constructed FAH/RAG1/IL2RG triple-knockout pig models were characterized by chronic liver injury and severe immunodeficiency. Importantly, the FG pigs transplanted with primary human hepatocytes produced human albumin in a time dependent manner as early as 1 week after transplantation. Furthermore, the colonization of human hepatocytes was confirmed by immunochemistry staining. Conclusions We successfully generated pig models with severe immunodeficiency that could construct human liver tissues.

In the original publication, there are errors in Fig. 3D and Fig. 5C and are corrected as follows.

A prediction model for machining deformation considering machining-induced residual stress (MIRS) and initial residual stress (IRS) of the blank is proposed in the present study based on the equivalent stiffness numerical calculation and elastic mechanics. The deflections of six thin-walled parts (includes two thin-walled specimens designed in the present study and four cases in the literature [1]) are predicted using the proposed model, and the corresponding finite element analysis (FEA) and experiments are implemented to verify the model. The machining deformation can be ultimately expressed by MIRS and IRS with the influence coefficients on the basis of the proposed model, and the effects of MIRS and IRS on the machining deformation are analyzed. It is shown that the predicted deformation by the proposed model has a good consistency with the FEA and experiment results. By comparison with the model only considering IRS in literature [1], the prediction accuracy visibly increases when both MIRS and IRS are considered. The contribution ratio of MIRS and IRS on the machining deformation is affected by the stress magnitude and depth, equivalent bending stiffness, and material removal rate. Also it can be easily gotten based on the proposed model.

A series of carbon-based binary single-atom catalysts of Fe and Ni coordinated by nitrogen are fabricated using a glucose-chelating method. Depending on the Ni/Fe content, they exhibit a wide-range of controllable CO/H2 ratio from 0.14 to 10.86, which is meaningful to specific chemical processes. The durability of the catalyst is evaluated over an 8-hour period with no significant degradation of activity. The variation of the faradaic efficiency with Ni/Fe content is justified by density-functional-theory based calculation of the reaction barrier in both hydrogen evolution and CO2 reduction reactions.

Metal-nitrogen-carbon materials are promising catalysts for CO2 electroreduction to CO. Herein, by taking the unique hierarchical carbon nanocages as the support, an advanced nickel-nitrogen-carbon single-site catalyst is conveniently prepared by pyrolyzing the mixture of NiCl2 and phenanthroline, which exhibits a Faradaic efficiency plateau of > 87% in a wide potential window of −0.6–−1.0 V. Further S-doping by adding KSCN into the precursor much enhances the CO specific current density by 68%, up to 37.5 A·g−1 at −0.8 V, along with an improved CO Faradaic efficiency plateau of > 90%. Such an enhancement can be ascribed to the facilitated CO pathway and suppressed hydrogen evolution from thermodynamic viewpoint as well as the increased electroactive surface area and improved charge transfer fromkinetic viewpoint due to the S-doping. This study demonstrates a simple and effective approach to advanced electrocatalysts by synergetic modification of the porous carbon-based support and electronic structure of the active sites.

To investigate the genetic features and biological costs of the plasmid pTW4 harboring tet(M) in an isolate of Escherichia coli ST162 from a duck. The complete nucleotide sequence of plasmid pTW4 was determined. The characteristics of plasmid pTW4 in E. coli were investigated by stability and direct competition assays. pTW4 is an IncHI2-type plasmid that contained the resistant genes tet(M), floR, strAB, sul2, rmtB, and blaCMY-2. Tet(M) is located in the composite transposon Tn6539 within the multidrug resistant (MDR) region on this plasmid. Furthermore, the resistance gene rmtB and blaCMY-2 were found outside the MDR region. The plasmid pTW4 remained stable in the host strain E. coli J53 after passage under an antibiotic-free environment for 7 days. However, the strain E. coli J53/pTW4 showed a fitness disadvantage of 6% per ten generations in the process of growth competition with E. coli J53. In conclusion, the plasmid pTW4, a mobile MDR vehicle, may promote the dissemination of tet(M), floR, rmtB, strAB, sul2, and blaCMY-2 among bacteria and then, but it appears to confer growth disadvantage to the host.

Flow prediction at a citywide level is of great significance to traffic management and public safety. Since deep learning has achieved success to deal with complex nonlinear problems, it has drawn increasing attention on making crowd flows prediction through neural networks. Generally, convolutional neural network (CNN) and recurrent neural network (RNN) have been applied to model the spatial-temporal dependency of the city. However, there are still two major challenges in predicting flows. First, it is difficult to train the model with the ability to capture both the nearby and distant spatial dependency by deep local convolutions. Second, daily and weekly patterns in temporal dependency are not strictly periodic for their dynamic temporal shifting in each region. To address these issues, we propose a novel deep learning model which called Local-Dilated Region-Shifting Network (LDRSN). LDRSN combines local convolutions with dilated convolutions to learn the nearby and distant spatial dependency. Furthermore, a new region-level attention mechanism is proposed to model the temporal shifting which varies by region. In the experiments, we compare the proposed method with other state-of-the-art methods in two real-world crowd flows datasets. The Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), Root Mean Square Error (RMSE) were used as the evaluation indexes. The experiment results show the effectiveness of the proposed model.

The electrochemistry in energy conversion and storage (ECS) not only relies on the active species in catalysts or energy-storage materials, but also involves mass/ion transport around the active species and electron transfer to the external circuit. To realize high-rate ECS process, new architectures for catalysts or energy-storage electrodes are required to ensure more efficient mass/charge transport. 3D porous mesostructured materials constructed by nanoscale functional units can form a continuous conductive network for electron transfer and an interconnected multiscale pores for mass/ion transport while maintaining the high surface area, showing great promise in boosting the ECS process. In this review, we summarize the recent progress on the design, construction and applications of 3D mesostructured carbon-based nanocages for ECS. The role of the hierarchical architectures to the high rate performance is discussed to highlight the merits of the mesostructured materials. The perspective on future opportunities and challenges is also outlined for deepening and extending the related studies and applications.

As a choke point in water electrolysis, the oxygen evolution reaction (OER) suffers from the severe electrode polarization and large overpotential. Herein, the porous hierarchical hetero-(Ni3-xFex)FeN/Ni catalysts are in situ constructed for the efficient electrocatalytic OER. X-ray absorption fine structure characterizations reveal the strong Ni-Fe bimetallic interaction in (Ni3-xFex)FeN/Ni. Theoretical study indicates the heterojunction and bimetallic interaction decrease the free-energy change for the rate-limiting step of the OER and the overpotential thereof. In addition, the high conductivity and porous hierarchical morphology favor the electron transfer, electrolyte access and O2 release. Consequently, the optimized catalyst achieves a low overpotential of 223 mV at 10 mA·cm-2, a small Tafel slope of 68 mV·dec-1, and a high stability. The excellent performance of the optimized catalyst is also demonstrated by the overall water electrolysis with a low working voltage and high Faradaic efficiency. Moreover, the correlation between the structure and performance is well established by the experimental characterizations and theoretical calculations, which confirms the origin of the OER activity from the surface metal oxyhydroxide in situ generated upon applying the current. This study suggests a promising approach to the advanced OER electrocatalysts for practical applications by constructing the porous hierarchical metal-compound/metal heterojunctions.

Fe3O4 magnetic nanoparticles (MNPs) can control and remove heavy metal pollution from wastewater. This approach has gained broad attention due to its excellent surface properties. However, there have been limited studies for Cu2+ retention and transfer regulation in saturated porous media in the presence of MNPs. The objectives of this study were to analyze the migration and deposition mechanism of Cu2+ under different conditions through static adsorption and numerical models. The results indicated that the MNPs-quartz sand had better adsorption capacity for Cu2+ (59.1 mg/kg) than quartz sand only (26.84 mg/kg), and thus it inhibited the migration of Cu2+; the effect improved with increasing MNP content. Furthermore, high ion strength (IS) and flow velocity were beneficial to the migration of Cu2+, and a high pH inhibited the migration of Cu2+. The numerical simulation results showed that the two-site model (TSM) nicely fitted the migration of Cu2+ in quartz sand and MNPs-sand. The migration of Cu2+ in both media was affected by chemical nonequilibrium. We also found that the presence of MNPs had little impact on the dispersion of porous media by observing the fitting parameters D (dispersion coefficient) 0.202 for both media. Our results can evaluate the risk of heavy metal migration and retention in saturated porous media in the presence of nanoparticles; this can prevent aquifer pollution.

The probabilistic control volume method has great prospects in correlating the effects of specimen size, notch and loading type on fatigue life or fatigue strength. In this work, the effects of notch size and loading type on fatigue life are investigated by using the probabilistic control volume method. Rotating bending and axial loading fatigue tests are at first performed on the hourglass specimen, circumferential V-notch specimen and V-notch plate specimen of 30CrMnSiA steel. Experimental results indicate that the notch reduces the fatigue strength of specimens in terms of nominal stress amplitude while in terms of local stress amplitude, the notch specimen could endure higher fatigue strength. Then, the probabilistic control volume method is used to evaluate the effects of notch size and loading type on fatigue life. It is shown that the probabilistic control volume method correlates well the effects of notch size and loading type on fatigue life, even for the local stress of the notch root exceeding the yield stress of the material.