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[Display omitted] With the proposal of carbon peaking and carbon neutrality goals, clean energy storage is attracting more and more attentions. In view of the lack of lithium resource in our earth, sodium-ion batteries are considered as the emerging and promising next-generation energy storage devices. Appropriate high-performance anode materials play a vital role in the development of sodium-ion batteries. Here, a core-shell hollow Ni-Co-P nanopolyhedron interconnected by oxygen defect TiO 2 (Ni-Co-P@TiO 2- x) is reported, which is synthesized by ion etching-hydrolysis and subsequent phosphatization/hydrogenation treatment using ZIF-67 as template and hybrid carbon source. The achieved Ni-Co-P@TiO 2- x material has several distinct advantages including hollow core-shell structure, flexible conductive carbon matrix, stable electroactive coating layer, and efficient pseudocapacitive behavior, resulting in high reversible capacities, remarkable rate capability and excellent cycle stability. The synergetic battery-capacitor characteristic of Ni-Co-P@TiO 2- x material makes it become a promising anode for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Na 2 MnPO 4 F particles-embedded carbon nanofibers are prepared. • Mechanism of pre-oxidation on architecture of nanofibers is investigated. • Carbon matrix with heat-resistance structure formed after pre-oxidation. • The pre-oxided nanofibers exhibit improved electrochemical performance. The rational design of an excellent architecture for active materials combined with carbon matrix is of particular importance to obtain flexible electrode material with high electrochemical properties. Well-designed nanofibers possess unique 3D network structure, which can significantly improve the electron/ion transportation and supplies sufficient active sites for Li+/Na+ insertion. Electrospinning-carbonization technology is a popular strategy to prepare nanofibers with active material embedded in carbon. It is found that the architecture of nanofibers tended to be wrecked and destroyed during the carbonization process without pre-oxidation treatment. In this study, we prepared Na 2 MnPO 4 F particles embedded in carbon nanofibers (Na 2 MnPO 4 F/C) using PVP as carbon source and investigated the strengthen mechanism of pre-oxidation on their architecture. The experiment and simulation results demonstrate that, without pre-oxidation, the main chain of PVP is severely ruptured during the carbonization procedure, consequently leads to fractured architecture of Na 2 MnPO 4 F/C nanofibers. In contrast, with pre-oxidation treatment, a long-chain and heat-resistance structured carbon matrix formed, and Na 2 MnPO 4 F/C nanofibers with stable architecture and improved electrochemical performance can be achieved. This study demonstrates a promising guide to construct carbon based nanofiber electrodes with stable architecture and high electrochemical performance. [ABSTRACT FROM AUTHOR]

Lithium-sulfur batteries have attracted numerous attentions owing to their high theory discharge specific capacity and energy density. However, sulfur cathode usually suffers from poor cycle stability and slow reaction kinetics, caused by its poor conductivity, excessive volume changes during charge/discharge processes, complex sulfur species conversion reaction and the dissolution of polysulfide intermediates. Here, we present a free-standing framework of Mn 3 O 4 nanoparticles combine with polypyrrole (PPy) nanotubes as host materials for lithium-sulfur batteries to overcome these issues. In this construction, PPy nanotubes serve as the excellent container of sulfur and physical barrier for the excessive volume expansion of sulfur during electrochemical reaction processes, and the nanotubes also provide an efficient conductive network for the rapid transmission of electrons and ions, while Mn 3 O 4 nanoparticles facilitate trapping lithium polysulfides. The coordination of PPy nanotubes and Mn 3 O 4 effectively alleviate the shuttle effect as well as enhance the utilization of sulfur. The obtained PPy@Mn 3 O 4 -S sample shows high capacities of 1419.9 and 925.5 mAh g−1 at 0.1 C and 1 C rate, respectively, and exhibits a low capacity fading rate of 0.062% per cycle for 800 cycles at 1 C rate. This work provides a new and effective way for the design of lithium-sulfur batteries with both high rate performance and long cycle stability. [ABSTRACT FROM AUTHOR]

Code cloning, which reuses a fragment of source code via copy-and-paste with or without modifications, is a common way for code reuse and software prototyping. However, the duplicated code fragments often affect software quality, resulting in high maintenance cost. The existing clone detectors using shallow textual or syntactical features to identify code similarity are still ineffective in accurately finding sophisticated functional code clones in real-world code bases. This article proposes functional code clone detector using attention (FCCA), a deep-learning-based code clone detection approach on top of a hybrid code representation by preserving multiple code features, including unstructured (code in the form of sequential tokens) and structured (code in the form of abstract syntax trees and control-flow graphs) information. Multiple code features are fused into a hybrid representation, which is equipped with an attention mechanism that pays attention to important code parts and features that contribute to the final detection accuracy. We have implemented and evaluated FCCA using 275 777 real-world code clone pairs written in Java. The experimental results show that FCCA outperforms several state-of-the-art approaches for detecting functional code clones in terms of accuracy, recall, and F1 score. [ABSTRACT FROM AUTHOR]

Layered transition metal oxide Na 0·67 Fe 0·5 Mn 0·5 O 2 is considered as a promising cathode material of sodium-ion batteries because of its naturally elemental abundance and high energy density. However, low rate capability and poor structural reversibility of Na 0·67 Fe 0·5 Mn 0·5 O 2 greatly hinder its large scale application. In this study, V-substituted Na 0·67 Fe 0·5 Mn 0·5 O 2 cathode material with improved electrochemical performance is successfully synthesized via a sol-gel method. The effects of V-substitution on chemical composition, crystal structure and morphology of Na 0·67 Fe 0·5 Mn 0·5 O 2 are studied in detail. Furthermore, modification mechanisms on the improved electrochemical performance by V-substitution are investigated. The results demonstrate that the rate capability and cycle stability of Na 0·67 Fe 0·5 Mn 0·5 O 2 cathode material is significantly elevated by V-substitution. And the enhanced electrochemical properties are mainly attributed to the improved Na+ diffusion rate and structural reversibility. This study suggests that introducing V ions into the lattice of Na 0·67 Fe 0·5 Mn 0·5 O 2 crystals is a favorable strategy to improve its electrochemical properties. [ABSTRACT FROM AUTHOR]

Black phosphorus is a potential candidate material for next-generation energy storage devices and has attracted tremendous interest because of its advantageous structural and electrochemical properties, including its large theoretical capacity, high carrier mobility, and low redox potential. However, its practical applicability has remained low owing to its difficult of preparation, large volume expansion during cycling, and poor electronic conductivity. To this end, there have been significant efforts to improve its synthesis methods and electrochemical performance. A number of black-phosphorus-based composite materials have been developed and investigated. Herein, we provide an up-to-date account of the recent progress made in research on black-phosphorus-based materials for use in rechargeable batteries and supercapacitors. We review the available synthesis methods and basic properties of black phosphorus and discuss its applicability in Li-, Na-, K-, Mg-, Al-ion and Li-S batteries as well as supercapacitors. We also summarize the existing challenges and future opportunities and offer our perspective on the possible directions for future research in this area. [ABSTRACT FROM AUTHOR]

P2-Na 2/3 Fe 1/2 Mn 1/2 O 2 is successfully synthesized via a facile spray-drying method followed by calcining at low temperature. The obtained material shows excellent discharge capacity, high rate capability and outstanding cycle ability. • P2-types Na 2/3 Fe 1/2 Mn 1/2 O 2 is synthesized by spray-drying method. • The temperature in the calcining process is decreased significantly. • The sample shows high capacity, excellent rate capability and cycle stability. Owing to its high theoretical capacity, P2-type Na 2/3 Fe 1/2 Mn 1/2 O 2 has been considered as a kind of promising cathode material. However, the practical application is limited due to excessively high calcining temperature during traditional preparation processes. Here, we report the synthesis of P2-Na 2/3 Fe 1/2 Mn 1/2 O 2 by using a facile spray-drying method followed by calcining at low temperature. Under the optimal conditions, the well-crystallized P2-Na 2/3 Fe 1/2 Mn 1/2 O 2 material with excellent rate capability and cycle ability is obtained. And the sample exhibits the initial discharge capacities of 217.9, 171.3 and 117.4 mAh g−1 at 0.1 C, 0.5 C and 2 C rate, respectively. The developed Na 2/3 Fe 1/2 Mn 1/2 O 2 material, synthesized by a new spray drying-calcining procedure, may potentially be used as a suitable cathode in sodium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract Carbon quantum dots/TiO 2 nanosheets with a majority of (001) facet (CQDs/TiO 2 -001) samples are successfully prepared via a facile method. Compared to TiO 2 -001 and CQDs/P25, the synthesized CQDs/TiO 2 -001 presents a remarkably higher photocatalytic activity for H 2 evolution with a considerable stability. XRD, XPS, HRTEM, FESEM, FTIR, Photoluminescence (PL) spectroscopy, Fluorescence spectroscopy and UV–visible reflectance spectroscopy are adopted to investigate the morphology, structure and properties of synthesized CQDs/TiO 2 -001. The mechanism of the improved photocatalytic activity over CQDs/TiO 2 -001 is also investigated. The results show that the improved photocatalytic activity over CQDs/TiO 2 -001 can be attributed to the synergistic effects of TiO 2 -001 and CQDs: the highly exposed (001) facets of TiO 2 -001 promote the transportation of photogenerated electrons and the loading of CQDs restrains the recombination of electrons-holes on (001) facets. Meanwhile, the visible-light absorption is extended because the CQDs serve as a photosensitizer and sensitize TiO 2 -001 through the newly formed Ti O C bond between the CQDs and TiO 2 -001. Graphical abstract Unlabelled Image Highlights • CQDs/TiO 2 with dominated (001) facet are prepared via a facile method. • CQDs/TiO 2 -001 exhibits excellent photocatalytic activity for H 2 evolution. • Synergistic effect of CQDs and (001) facet leads to superior performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Fe-doped TiO 2 with exposed (0 0 1) facets was prepared from Ti-bearing tailings. • F additive promotes tailings decomposition and exposure of (0 0 1) facets of TiO 2. • Synthesized TiO 2 shows high photocatalytic activity under visible light. Abstract Fe-doped TiO 2 nanoparticles with highly exposed (0 0 1) facets are directly synthesized from Ti-bearing tailings by a facile method for the first time. The effects of F-based additive on the decomposition rate of Ti-bearing tailings as well as exposure percentage of (0 0 1) facets are systematically investigated in this work. The results demonstrate that F-based additive agent effectively promotes decomposition of Ti-bearing tailings during the acidolysis process. What's more, F-based additive agent also plays a key role in the exposure of high-energy (0 0 1) facets for the obtained TiO 2 nanoparticles. Synthesized F-drived TiO 2 nanoparticles present outstanding photocatalytic activity on pollution degradation under visible and UV light. This study demonstrates a promising way to achieve advanced materials from secondary resources. [ABSTRACT FROM AUTHOR]

In this work, highly pure nano-TiO 2 photocatalysts with varying Fe doping concentration were successfully synthesized from low-cost Ti-bearing tailings by an acidolysis-hydrothermal route. The effects of H 2 SO 4 concentration, leaching temperature, acid/tailings ratio and leaching time on the recovery of TiO 2 from the tailings were investigated. Synthesized samples were characterized by XRD, TEM, EDS, XPS, and UV–vis spectroscopy. The results showed that the material prepared is characteristic anatase with the average size of 20 nm and the Fe doping concentration in the synthesized nano-TiO 2 is tunable. The photocatalytic activity of synthesized nano-TiO 2 photocatalyst was also evaluated by the photodegradation of Rhodamine B under visible light and UV light irradiation. Our study demonstrates a low-cost approach to synthesize highly efficient and visible light responsive catalysts. [ABSTRACT FROM AUTHOR]

Sunlight-driven hydrogen production from water splitting, assisted with the commonly used Pt/TiO 2 catalyst, is a promising way to store clean and renewable energy. However, the photocatalytic activity of Pt/TiO 2 is limited owing to the agglomeration of Pt atoms. Herein, we successfully synthesized a Pt/TiO 2 catalyst, where Pt is atomically and selectively dispersed on the (1 0 1) facets of nanosized TiO 2 single crystals. A remarkably higher photocatalytic activity for H 2 evolution together with a considerable stability was observed as compared to commonly used Pt/TiO 2 . This study demonstrates a promising way to achieve atomically dispersed highly-active catalyst for water splitting. [ABSTRACT FROM AUTHOR]

Spatial errors (e.g., buffer overflows) continue to be one of the dominant threats to software reliability and security in C/C++ programs. Presently, the software industry typically enforces spatial memory safety by instrumentation. Due to high overheads incurred in bounds checking at runtime, many program inputs cannot be exercised, causing some input-specific spatial errors to go undetected in today's commercial software. This paper introduces a new compile-time approach for reducing bounds checking overheads based on the notion of weakest precondition (WP). The basic idea is to guard a bounds check at a pointer dereference inside a loop, where the WP-based guard is hoisted outside the loop, so that its falsehood implies the absence of out-of-bounds errors at the dereference, thereby avoiding the corresponding bounds check inside the loop. This WP-based approach is applicable to any spatial-error detection approach (in software or hardware or both). To evaluate the effectiveness of our approach, we take SoftBound, a compile-time tool with an open-source implementation in low-level virtual machine (LLVM), as our baseline. SoftBound adopts a pointer-based checking scheme with disjoint metadata, making it a state-of-the-art tool in providing compatible and complete spatial safety for C. Our new tool, called WPBound, is a refined version of SoftBound, also implemented in LLVM, by incorporating our WP-based compiler approach comprising both intra and interprocedural optimizations. For a set of 20 C benchmarks selected from SPEC and MiBench,WPBound reduces the average runtime overhead of SoftB ound from 77% to 47% (by a reduction of 39%), with small code size increases. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface phosphorylated TiO 2 nanofibers with binary-phase are fabricated successfully. • The reactivity of TiO 2 nanofibers is boosted by surface phosphorylation treatment. • The synthesized SP-TiO 2 -A/B shows significantly improved electrochemical performance. TiO 2 -based nanostructure has been reported as one of the most developable anode materials for sodium-ion batteries, but its low capacity and poor rate capability bring an unavoidable challenge and impede the practical application. In this study, surface phosphorylated TiO 2 nanofibers with anatase/bronze binary-phase are fabricated using ion exchange-annealing treatment and subsequent phosphorylation. The resulting nanofibers can serve as an efficient electrode material for sodium storage, affording a reversible capacity of 224.7 mAh g−1 at 200 mA g−1 and a superior high-rate cycling capability of 108.9 mAh g−1 at 2000 mA g−1 after 1000 cycles. XPS and HRTEM reveal that the synthesized SP-TiO 2 -A/B nanofibers present heterojunction-boundary between anatase/bronze binary-phase and well-crystallized internal-structure with disordered/amorphous surface, and a high ratio of active surface was motivated through phosphorylation and Na+ ion storage behavior was efficiently modulated. The surface phosphorylation engineering provides a promising strategy to develop Na-storage electrodes with superior electrochemical performance. [ABSTRACT FROM AUTHOR]

We introduce a static detector, Saber, for detecting memory leaks in C programs. Leveraging recent advances on sparse pointer analysis, Saber is the first to use a full-sparse value-flow analysis for detecting memory leaks statically. Saber tracks the flow of values from allocation to free sites using a sparse value-flow graph (SVFG) that captures def-use chains and value flows via assignments for all memory locations represented by both top-level and address-taken pointers. By exploiting field-, flow- and context-sensitivity during different phases of the analysis, Saber detects memory leaks in a program by solving a graph reachability problem on its SVFG. Saber, which is fully implemented in Open64, is effective at detecting 254 leaks in the 15 SPEC2000 C programs and seven applications, while keeping the false positive rate at 18.3 percent. Saber compares favorably with several static leak detectors in terms of accuracy (leaks and false alarms reported) and scalability (LOC analyzed per second). In particular, compared with Fastcheck (which analyzes allocated objects flowing only into top-level pointers) using the 15 SPEC2000 C programs, Saber detects 44.1 percent more leaks at a slightly higher false positive rate but is only a few times slower. [ABSTRACT FROM PUBLISHER]

[Display omitted] Rechargeable lithium-sulfur (Li-S) batteries with environmental friendliness, low price, high specific capacity and energy density could be promising alternatives to a larger scope of energy storage in the near future. However, the practical application is impeded by the intrinsic insulation of sulfur and the fatal shuttle effect during the (dis)charging process. Herein, we report a strategy to address the drawbacks of Li-S batteries by inserting an interwoven carbon nanotubes/cerium dioxide electrocatalyst interlayer material (CNTs@CeO 2) between the sulfur cathode and the separator. In the CNTs@CeO 2 composite, the conductive network interwoven by CNTs facilitates electron transportation, and the abundant active sites in CeO 2 cavities ensuring the adsorption-catalytic conversion of lithium polysulfides as well as the hollow structure of CeO 2 is conducive to rapid electrolyte penetration and lithium ion migration. Benefiting from such multifunction, the battery with a CNTs@CeO 2 interlayer exhibits superior rate performance, delivering a high discharge specific capacity of 1040.6 mAh g−1 at 0.2C and 652.5 mAh g−1 at 4C, respectively. Moreover, the battery shows excellent cycling stability with a capacity decay rate of 0.064% per cycle at 1C over 1000 cycles. These promising results demonstrate the potential application of CeO 2 -based electrocatalysts for high energy density Li-S batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] Na 4 Fe 3 (PO 4) 2 (P 2 O 7) is regarded as a promising cathode material for sodium-ion batteries due to its affordability, non-toxic nature, and excellent structural stability. However, its electrochemical performance is hampered by its poor electronic conductivity. Meanwhile, most of the previous studies utilized spray-drying and sol–gel methods to synthesize Na 4 Fe 3 (PO 4) 2 (P 2 O 7), and the large-scale synthesis of the cathode material is still challenging. This study presents a composite cathode material, Na 4 Fe 2.94 Al 0.04 (PO 4) 2 (P 2 O 7)/C, prepared via a straightforward ball-milling technique. By substituting Al3+ minimally into the Fe2+ site of NFPP, Fe defects are introduced into the structure, hindering the formation of NaFePO 4 and thereby enhancing Na-ion diffusion kinetics and conductivity. Additionally, the average length of Al O bonds (2.18 Å) is slightly smaller than that of Fe O bonds (2.19 Å), contributing to the superior structural stability. The smaller ionic radii of Al3+ induce lattice contraction, further enhancing the structural stability. Moreover, the surface of material particles is coated with a thin layer of carbon, ensuring excellent electrical conductivity and outstanding structure stability. As a result, the Na 4 Fe 2.94 Al 0.04 (PO 4) 2 (P 2 O 7)/C cathode exhibits excellent electrochemical performance, leading to high discharge capacity (128.1 mAh g−1 at 0.2 C), outstanding rate performance (98.1 mAh g−1 at 10 C), and long cycle stability (83.7 % capacity retention after 3000 cycles at 10 C). This study demonstrates a low-cost, ultra-stable, and high-rate cathode material prepared by simple mechanical activation for sodium-ion batteries which has application prospects for large-scale production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ni, Mn co-doped FePO 4 @C is synthesized by an ion exchange method in aqueous media. • Heating is benefit to increase the delithiation rate of LiFePO 4. • Ni, Mn co-doping can effectively enhance the electronic conductivity of FePO 4. • Ni, Mn co-doping can obviously increase the working voltage of FePO 4 cathode. Olivine FePO 4 is widely regarded as an optimal cathode material for sodium-ion batteries due to its impressive theoretical capacity of 177.7 mAh g−1. Nonetheless, the material's limited application stems from its intrinsic low electronic and ionic conductivities and ion diffusion rate. Previously, most modifications of olivine FePO 4 are conducted through electrochemical or ion exchange processes in organic solvents, which severely restricted its potential for large-scale applications. In this research, a novel water-based ion exchange method is proposed for the synthesis of Ni-doped, Mn-doped, and Ni, Mn co-doped FePO 4 @C, which is non-toxic, cost-effective, and demonstrating promising prospects for various applications. Fe 2.7 Mn 0.2 Ni 0.1 PO 4 @C (0.2Mn0.1Ni-FP@C) is synthesized by a straightforward ion exchange method in aqueous media. The material exhibits a discharge capacity of 154.4 mAh g−1 at 0.1C rate. After 300 cycles at 1C, the capacity retention rate remains at 70.7 %. Numerous tests and calculations conducted in this study demonstrate that 0.2Mn0.1Ni-FP@C, modified through Mn3+ and Ni3+ co-doping, exhibits superior electrochemical performance due to its enhanced electronic conductivity and ion diffusion rate. [ABSTRACT FROM AUTHOR]

• Nanoporous Na 2 Fe 1- x Mn x PO 4 F/C composites are synthesized by spray drying method. • Na 2 Fe 0.6 Mn 0.4 PO 4 F/C cathode shows much enhanced sodium storage performance. • Reaction kinetics of Na 2 Fe 0.6 Mn 0.4 PO 4 F/C is revealed by EIS for the first time. • Strategies to enhance the properties of Na 2 Fe 0.6 Mn 0.4 PO 4 F/C are concluded. It is a challenge to develop a facile and scaleable approach to boost the application of high-energy fluorinated iron/manganese phosphate cathode materials for sodium-ions batteries. In this study, for the first time, the porous Na 2 Fe 1- x Mn x PO 4 F/C (x = 0.2, 0.4, 0.6, 0.8) nanocomposites are successfully designed via spray drying, following in-situ pyrolytic carbonization process. To examine this synergetic design, the rate capability, cycling stability, and reaction kinetics of the cathode materials are investigated in detail. It is found that the solid solution Na 2 Fe 0.6 Mn 0.4 PO 4 F/C cathode delivers the high discharge capacities of 94.8 and 30.0 mAh g−1 at 0.05 C and 1.0 C, respectively, and a reversible capacity of 51.0 mAh g−1 after 100 cycles at 0.2 C with a capacity retention of 89.3%. Particularly, the cycling stability as well as rate capability of Na 2 Fe 0.6 Mn 0.4 PO 4 F/C are superior to those of the other Na 2 Fe 1- x Mn x PO 4 F/C solid solutions and the two-phase mixture of Na 2 MnPO 4 F/C and Na 2 FePO 4 F/C. Furthermore, the potential strategies to further improve the electrochemical performance of Na 2 Fe 0.6 Mn 0.4 PO 4 F/C cathode are proposed based on the kinetics analysis of its electrochemical impedance spectroscopy spectra at various charge/discharge depths. It is expected that our research strategies and findings can be extended to other electrode materials in Li+/Na+ storage and beyond. [ABSTRACT FROM AUTHOR]

Abstract In this paper, a combined-method study has been made on the lateral muscle of the teleost olive flounder Paralichthys olivaceus in just-hatched and adult stages. In just-hatched stage, both slow and fast muscle fibres were detected: (1) in situ hybridization analysis indicated that slow and fast myosin heavy chain genes were specifically expressed in the superficial and deep part of the myotomal muscle, respectively; (2) immunohistochemistry analysis showed that fibres in the deep part reacted with anti-fast myosin antibody F310; (3) western blot analysis detected a weak expression of slow myosin and a strong expression of fast myosin. In adult stage, the slow and fast muscle fibres had their own distribution characteristics: (1) hematoxylin/eosin staining showed the histological characteristics of the muscle fibre composition; (2) histochemical observations showed that the deep muscle fibres, and some fibres near the epidermis, contain alkali-stable myofibrillar ATPase activity; (3) immunohistochemistry analysis indicated that all the deep muscle fibres reacted with F310 antibody and some fibres in the superficial layer of muscle also reacted with F310; (4) western blot analysis showed that fast myosin was expressed both in the blended muscles (the mix of superficial and deep muscles) and deep muscles, while slow myosin was mainly expressed in the blended muscles. These findings suggested that both slow and fast muscle fibres existed in the musculature of the olive flounder in just-hatched and adult stages. Notably, the adult fast fibres also exist in the superficial layer of the muscle. [ABSTRACT FROM AUTHOR]

There are several challenges (e.g., imbalance between supply and demand of hardware resources and software licenses, and usability) under modern High-Performance Computing (HPC) environment. As a means of providing an on-demand service for end users, we propose a Software-as-a-Service (SaaS) approach for managing commercial HPC applications as a Web-based service deployed on top of federated clouds. Some inter-trusted private or public clouds are federated to create a unified service platform with a large amount of hardware resources. In addition, an on-demand, pay-per-use model for Web-service-enabled HPC applications is proposed. Further, we provide an economic analysis of the proposed approach from the perspective of end users, cloud service providers, and Independent Software Vendors (ISVs). We conduct a simulation using two HPC application services on three federated clouds. A combined Quality of Service (QoS) and economic evaluation demonstrates a better effect of the proposed approach comparing with existing HPC platforms. [ABSTRACT FROM AUTHOR]

For the first time, a one-step synthetic strategy has been developed towards the preparation of Ti 3+ self-doped TiO 2 with internal-pores and highly exposed {001} facets using ethylene glycol (EG) and HF as control agents. The obtained samples were characterized by XRD, XPS, SEM, TEM, HAADF-STEM, photoluminescence spectroscopy (PL), and UV–vis reflectance spectroscopy. The synergistic effect of EG and HF plays a vital role in the formation of synthesized TiO 2 with Ti 3+ self-doping, internal-pores and highly exposed {001} facets. As-synthesized TiO 2 exhibit much higher activity than commercial P25 on photocatalytic degradation of phenol and the outstanding performance is attributed to the synergistic effect of Ti 3+ doping, internal-pores, and facets heterojunction. [ABSTRACT FROM AUTHOR]

Na 2 MnPO 4 F has become a promising cathode candidate for next generation sodium ion batteries by virtue of its high working potential and theoretical capacity, but its electrochemical performance is restricted by its low electronic conductivity and sluggish Na+ diffusion. In this study, Na 3 V 2 (PO 4) 2 F 3 is introduced into the Na 2 MnPO 4 F cathode material to improve the electron/ionic conductivity by generating lattice defects and providing active sites for Na+ transportation. The structure, morphology and electrochemical properties of x Na 2 MnPO 4 F· y Na 3 V 2 (PO 4) 2 F 3 /C materials are investigated thoroughly. It is found that the electrochemical performance of Na 2 MnPO 4 F is significantly elevated by the modification of Na 3 V 2 (PO 4) 2 F 3. The optimized lotus root-like porous Na 2 MnPO 4 F·Na 3 V 2 (PO 4) 2 F 3 /C cathode material delivers the first specific discharge capacity of 126.6 mAh·g−1 at 0.05C, which is close to the theoretical specific capacity. Furthermore, the Na 2 MnPO 4 F·Na 3 V 2 (PO 4) 2 F 3 /C cathode material also presents good rate performance (76.9 mAh·g−1 at 1C rate), and remains 93.2% capacity retention after 400 cycles. This paper demonstrates a promising guide to construct Na 2 MnPO 4 F-based cathode materials with superior electrochemical performance for sodium ion batteries. [Display omitted] [ABSTRACT FROM AUTHOR]

In teleost fish, primordial germ cells (PGCs) are specified very early during embryogenesis and migrate to the site that gonads are formed. A previous study indicated that nanos3 is specifically expressed in PGCs, and the 3′ untranslated region (UTR) of nanos3 is responsible for the localization of mRNA in these cells. In this study, we aimed to investigate the functional regions of nanos3 3′UTR in olive flounder using truncated and mutated nanos3 3′UTRs fused to chimeric RNAs and microinjected into fertilized zebrafish eggs. The results indicated that a 68-bp functional element in the nanos3 3′UTR of olive flounder played important roles in the protection and degradation of RNA. Within this element, a U-rich region was identified to be responsible for the protection of RNA in PGCs and two GCAC sites for the degradation of RNA in somatic cells. The first GCAC was located adjacently to the U-rich region and the second GCAC within the U-rich region. Overall, we concluded that the two GCACs were the binding sites of miR-430, a microRNA that suppresses translation, whereas the U-rich region was the binding site of Dnd, a protein that antagonizes the miR-430-mediated silencing of mRNA. [ABSTRACT FROM AUTHOR]

In view of the inferior specific capacity and low rate capability of titanium dioxide with individual-phase, multi-sized anatase/bronze nanoribbons with heterojunction structure are prepared by a hydrothermal ion exchange method in this study. The effects of calcination temperature on the crystallographic structure, architecture morphology and electrochemical properties of anatase/bronze nanoribbons are investigated. The results show that the prepared anatase/bronze nanoribbons present one-dimensional nanostrips structure with a bandwidth of about 100 nm, and nanofibers are attached to the surface. It is found that calcination temperature is critic in the crystallographic structure, architecture morphology and electrochemical performance of anatase/bronze nanoribbons. The multi-sized anatase/bronze nanoribbons prepared at 300 °C show improved electrochemical performance with superior specific capacity, outstanding rate capability and long cycle life. At the current density of 200 mA·g−1, the specific discharge capacity of the first circle reaches 728 mAh·g−1. Moreover, the specific discharge capacity remains 92.5 mAh·g−1 after 2000 charge-discharge cycles 2000 mA·g−1. The design of anatase/bronze heterojunction structure supplies a potential strategy to develop titanium-based anode with advantageous electrochemical performance. [Display omitted] • Multi-sized anatase/bronze nanoribbons with heterojunction was prepared. • Multi-sized architecture and heterojunction promote sodium storage. • As-obtained anatase/bronze nanoribbons showed good electrochemical performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • An organic interlayer is introduced between Li 1.2 Ti 0.4 Mn 0.4 O 2 and carbon layer. • The interlayer can effectively restrain oxygen release of Li 1.2 Ti 0.4 Mn 0.4 O 2. • The structural stability of Li 1.2 Ti 0.4 Mn 0.4 O 2 is significantly improved. • The modified Li 1.2 Ti 0.4 Mn 0.4 O 2 presents superior electrochemical performance. A typical cation-disordered rock-salt oxide, Li 1.2 Ti 0.4 Mn 0.4 O 2 , is considered as one of the most promising cathode candidate materials for the next generation of lithium-ion battery due to its high specific capacity, outstanding energy density, low cost and nature abundant resource. However, rapid capacity fading and voltage attenuation originated from severe oxygen release at the surface of Li 1.2 Ti 0.4 Mn 0.4 O 2 seriously hindered its practical application. To date, carbon coating strategy has been proposed to suppress oxygen release. But the poor actual effect and accompanying capacity loss caused by onefold carbon layer herald carbon is not a suitable coating material for Li 1.2 Ti 0.4 Mn 0.4 O 2. Herein, a specific organic interlayer is constructed via the polymerization of 3,4-ethylenedioxythiophene (EDOT), by which dense and conductive poly EDOT layer is adhered between Li 1.2 Ti 0.4 Mn 0.4 O 2 core and carbon layer. The novel interlayer modification strategy can effectively restrain oxygen release and significantly improve the electrochemical performance of Li 1.2 Ti 0.4 Mn 0.4 O 2. This work demonstrates the practicability and feasibility of carbon layer and EDOT interlayer cooperative coating strategy for optimizing the electrochemical performance of cation-disordered rock-salt oxides. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel pure bimetallic-polyanion Na 4 Fe 2.82 Ni 0.18 (PO 4) 2 P 2 O 7 cathode is produced. • Ni-substituting inhibits the generation of NaFePO 4 impurity during the synthesis. • Ni-substituting and N-doping significantly improve the conductivity of cathode. • The Na 4 Fe 2.82 Ni 0.18 (PO 4) 2 P 2 O 7 @C-N exhibits superior sodium-storage performance. Na 4 Fe 3 (PO 4) 2 P 2 O 7 , with the advantages of strong structural stability, suitable voltage window, low cost and green pollution-free, is considered as a highly researchable cathode material for sodium-ion batteries. However, the low conductivity of Na 4 Fe 3 (PO 4) 2 P 2 O 7 and the inevitable electrochemical inertia from maricite-NaFePO 4 impurity during the preparation process lead to the low reversible capacity and poor cycling stability. In this work, a new bimetallic-polyanion cathode material Na 4 Fe 2.82 Ni 0.18 (PO 4) 2 P 2 O 7 capped with an in-situ nitrogen-doped carbon layer is proposed. Ni-substituting inhibits the generation of electrochemical inert maricite-NaFePO 4 impurity and enhances the Na+ ion conductivity. Meanwhile, a lower volume-change during the charging/discharging process can be achieved in Na 4 Fe 2.82 Ni 0.18 (PO 4) 2 P 2 O 7 electrode compared with conventional Na 4 Fe 3 (PO 4) 2 P 2 O 7 electrode. With the synergistic effect of in-situ N-doping and Ni-substituting, an ultra-high initial discharge capacity (128.4 mAh g−1 at 0.2C), superior rate performance (62.5 mAh g−1 at 50C) and significant long-term cycle life (capacity retention rate of about 83 % after 3000 cycles at 10C) can be achieved in the optimal Na 4 Fe 2.82 Ni 0.18 (PO 4) 2 P 2 O 7 @C-N (Ni6-NFPP@C-N) cathode. This study suggests a practical strategy to produce Na 4 Fe 3 (PO 4) 2 P 2 O 7 -based electrode material with no impurities and superior electrochemical properties for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cassia seed-derived N-P double-doped porous carbon is prepared by a puffing method. • The novel architecture can increase sulfur loading and reduce volume expansion. • The N-P doped C-S composite exhibits excellent electrochemical performance. As biochar exhibits a unique structure and electrical conductivity, application of biochar in batteries arouses huge attention. In the present study, the cassia seed-derived N-P double-doped porous carbon which acts as a carrier of sulfur cathode is prepared based on a fast, powerful puffing of cassia seed with subsequent annealing treatment route. After loading sulfur into the porous carbon, the carbon–sulfur composite is employed as the cathode material of lithium-sulfur batteries. It is found that by puffing process with the popcorn machine, cassia seeds can successfully change into porous carbon with numerous mesopores based on considerable large pores. This special architecture can effectively capture the lithium polysulfide intermediates and inhibit the volume of sulfur from expanding simultaneously. Meanwhile, the N-P double-doped carbon can alter the hybridization orbital of carbon and facilitate the chemical adsorption of lithium polysulfide, thereby expediting the cycle of S cathode. The N-P doped carbon–sulfur composite exhibits a maximum discharge capacity of 1464.4 mAh/g at 0.1C and maintains a high discharge capacity of 825.8 mAh/g after 100 cycles at 5C. This study presents an economical, green and sustainable method to synthesis N-P double-doped porous carbon–sulfur composite which has large-scale application prospects in lithium-sulfur batteries. [ABSTRACT FROM AUTHOR]

A cohesive architecture of 1T-MoS 2 covered by PPy composite (1T-MoS 2 @PPy) is successfully fabricated by a simple hydrothermal reaction followed by an in-situ polymerization route. The composite material consists of 1T-MoS 2 hollow microsphere and conductive PPy coating layer. The cohesive architecture enables the composite to show rapid shuttle of electrons/lithium ions and good ductility to buffer the volume changes during charging and discharging process when it is used as anode material. As expected, 1T-MoS 2 @PPy composite exhibits a favorable discharge capacity up to 970.3 and 407.1 mAh g−1 at 0.2 and 3 A g−1, respectively. In addition, the composite also achieves impressive cycling performance of 717.1 mAh g−1 at 1 A g-1 after 500 cycles. This study provides a meaningful guidance in rational design of anode materials with cohesive architecture as well as high electrochemical performance. [ABSTRACT FROM AUTHOR]

We designed and engineered the construction of conductive PPy-decorated hydrangea-type 1T-MoS 2 as a cathode host material for high-energy-density and long-life Li-S batteries. [Display omitted] • PPy-encapsulated hydrangea-type 1 T-MoS 2 sulfur host was successfully prepared. • 1 T-MoS 2 @PPy shows favorable catalytic activities to LiPSs/Li 2 S redox reactions. • The synergistic effect of 1 T-MoS 2 and PPy promoted the conversion of LiPSs. • Hierarchical architecture of 1 T-MoS 2 @PPy is benefit to electron/ion transfer. • 1 T-MoS 2 -S@PPy cathode exhibits high-rate and ultra-stable cycling performance. Lithium-sulfur batteries are regarded as promising candidates for next-generation energy storage applications owing to their high theoretical specific capacity, low cost, and eco-friendliness. However, the poor conductivity, large volume variation of sulfur species during the charging/discharging process, complicated conversion reactions of sulfur species, shuttle effect of lithium polysulfide, and low sulfur loading greatly hinder the practical application of lithium-sulfur batteries. In this study, we propose an efficient approach to design polypyrrole (PPy)-encapsulated 1T-MoS 2 microspheres with a hydrangea-like structure as catalytic sulfur hosts for lithium-sulfur batteries. The catalytic effect of 1T-MoS 2 and the high conductivity of the PPy layer accelerated the adsorption/conversion of lithium polysulfides. The hydrangea-like structure of the 1T-MoS 2 microspheres provided adequate number of active sites and sufficient space for sulfur loading. Meanwhile, the specific inter-porous/outer-coating layer structure could also restrain the expansion of sulfur electrode during the electrochemical reaction process. The obtained 1T-MoS 2 -S@PPy cathode material exhibited outstanding electrochemical performance with an excellent reversible capacity of 1434 mAh g−1 at 0.1C rate, a considerable capacity of 1023 mAh g−1 at 1C rate, and excellent cycling stability for over 800 cycles with a low cycling decay rate of 0.051% per cycle. [ABSTRACT FROM AUTHOR]

[Display omitted] • Na 4 MnCr(PO 4) 3 /C is firstly prepared by a facile modified solid phase method. • The chelating effect of citric acid is benefit to synthesis pure Na 4 MnCr(PO 4) 3. • 3D porous architecture can improve the conductivity of Na 4 MnCr(PO 4) 3. • Suitable carbon layers can improve the structural stability of Na 4 MnCr(PO 4) 3. Na 4 MnCr(PO 4) 3 is a promising cathode material with high redox potential and high energy density, but the intrinsic poor electronic conductivity and substandard structural stability restrict its practical application. Herein, porous Na 4 MnCr(PO 4) 3 /C with conductive networks and improved electrochemical properties is synthesized by a facile modified solid-state process using citric acid as a multifunctional additive. The results reveal that citric acid can be used as a grinding aid to make the raw materials mix more evenly and speed up the efficiency of ball milling. Besides, 3D conductive network and porous structure originated from polycondensation and carbonization of citric acid can promote the electrochemical properties of Na 4 MnCr(PO 4) 3 /C by enhancing the electronic/ionic conductivity and (de)intercalation reaction kinetics. As expected, the optimal Na 4 MnCr(PO 4) 3 /C delivers a high reversible capacity of 130.5 mAh g−1 at 0.1C rate, and exhibits a capacity retention of 82.62% at 10C rate after 500 cycles. In addition, the reversible biphasic reaction of the cathode is confirmed by the constant galvanostatic intermittent titration technique and ex-situ XRD, which shows great potential of the synthesized Na 4 MnCr(PO 4) 3 /C for practical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • CeO 2 hollow spheres embedded in N-doped carbon fiber are successfully prepared. • CeO 2 @NCF shows favorable structural stability and lithium storage active sites. • The synergistic effect of CeO 2 and NCF promoted the (de)intercalation of Li+. • Fibrous architecture of CeO 2 @NCF is benefit to electron/ion transfer. • CeO 2 @NCF anode delivers high-rate and ultra-stable cycling performance. Over the past two decades, the usage of lithium-ion batteries (LIBs) has increased dramatically in routine life, nevertheless, the current drawbacks of LIBs threaten their dominance. This work proposes a novel structure of nitrogen-doped carbon fiber embedded with cerium oxide hollow spheres (CeO 2 @NCF), which establishes a stable boundary between the electrolyte and anode to prolong the battery lifespan. Besides, NCF with advantages of high conductivity and good elasticity is conducive to mitigate the volume change of CeO 2 as well as sustains the structural integrity during the (dis)charge processes; meanwhile, it can ensure the rapid redox reactions, and inhibit side reactions. The hollow spherical structure of CeO 2 , along with its rich vacancies, affords extra catalytic sites for the accumulation and transportation of Li+. Encouragingly, LIB based on the synergistic effects of CeO 2 and NCF exhibits high capacity and outstanding cyclic stability, which shows a discharge capacity of 450.8 mAh/g after 500 cycles at 1 A/g. This result indicates a promising path with the rational structural design of anode materials based on rare earth metal-oxides for the advanced LIBs. [ABSTRACT FROM AUTHOR]

Identifying security bug reports (SBRs) accurately from a bug repository can reduce a software product’s security risk. However, the class imbalance problem exists for SBR prediction since the number of SBRs is often limited, and this issue has not been thoroughly investigated in previous studies. In our study, we choose six real-world projects of different sizes with over 120 000 bug reports in total as our empirical subjects. We first analyze the impact of the class imbalance issue on SBR prediction and confirm its negative impact on prediction performance. Then we perform a comparative study of six state-of-the-art class rebalancing methods combined with five popular classification algorithms for SBR prediction. By comparing with the baseline method Farsec, using the class rebalancing methods can improve the performance in 78% of cases in the worst case. Moreover, the combination of the Rose and random forest classification algorithm can construct the model with the best performance, which increases the performance by 267% in the best case and 75% on average in terms of F1-score. Finally, we summarize eight main findings based on our empirical studies’ results, which can provide guidelines for choosing appropriate class rebalancing methods and classifiers for SBR prediction in practice. [ABSTRACT FROM AUTHOR]

Regression bugs are a type of bugs that cause a feature of software that worked correctly but stop working after a certain software commit. This paper presents a systematic study of regression bug chains, an important but unexplored phenomenon of regression bugs. Our paper is based on the observation that a commit $c1$ , which fixes a regression bug $b1$ , may accidentally introduce another regression bug $b2$. Likewise, commit $c2$ repairing $b2$ may cause another regression bug $b3$ , resulting in a bug chain, i.e., $b1\rightarrow c1\rightarrow b2\rightarrow c2\rightarrow b3$. We have conducted a large-scale study by collecting 1579 regression bugs and 2630 commits from 57 Linux versions (from 2.6.12 to 4.9). The relationships between regression bugs and commits are modeled as a directed bipartite network. Our major contributions and findings are fourfold: 1) a novel concept of regression bug chains and their formulation; 2) compared to an isolated regression bug, a bug on a regression bug chain is much more difficult to repair, costing 2.4× more fixing time, involving 1.3× more developers and 2.8× more comments; 3) 85.8% of bugs on the chains in Linux reside in Drivers, ACPI, Platform Specific/Hardware, and Power Management; and 4) 83% of the chains affect only a single Linux subsystem, while 68% of the chains propagate across Linux versions. [ABSTRACT FROM AUTHOR]

It is a great challenge to develop the cathode materials with high efficiency, long life and low-cost for lithium-sulfur batteries. In this paper, we design a simple hydrothermal method to synthesize MoS 2 wrapped the MOFs-derived N-doped carbon nanorods as an effective sulfur host to improve the electrochemical performance of lithium-sulfur batteries. In the hydrothermal process, the cubic zeolitic imidazolate framework-67 (ZIF67) particles are connected together to form nanorods, and MoS 2 nanosheets are wrapped on the surface of the nanorods. In this composite, the carbon nanorods derived from ZIF67 is the main host for S-loading, while N-doping can change the hybrid orbital form of carbon and significantly improve the chemical adsorption of polysulfide. The elemental cobalt and cobalt oxide derived from ZIF67 can improve the electronic conductivity and polarity of the composite. And MoS 2 coating layer can provide more active sites, accelerate the sulfur redox reactions and effectively restrain the shuttle effect. The synergetic effects of above-mentioned factors make the MoS 2 @CZIF67/S composite cathode material shows excellent electrochemical performance. The composite shows high reversible specific capacities of 1391.9 and 806.1 mAh g−1 at 0.1C and 1C rate, respectively, and exhibits a capacity retention of 70.5% after 400 cycles at 1C rate. [ABSTRACT FROM AUTHOR]

Searching for affordable and efficient anode materials is of great significance for the development of sodium-ions batteries. Anatase-based electrode material has demonstrated reasonably voltage and outstanding cyclability. However, low specific capacity and poor Na+ transmission efficiency of conventionally prepared anatase material restrain its practical application. To achieve anatase-based electrode material with superior sodium storage, pompon-villus shaped hydrogen titanate/anatase composite with heterostructure is synthesized by a facile method. Thanks to the cooperative effect of unique pompon-villus architecture, open channel of hydrogen titanate, and specific heterostructure, the synthesized composite displays excellent rate performance and long cycle performance: the discharge specific capacity is remains 157.8 mAh·g−1 after 200 cycles at 0.1 A·g−1, and the discharge specific capacity is maintaining 104.1 mAh·g−1 after 1000 cycles at 2 A·g−1. This work supplies new fundamental strategy and paves an encouraging avenue in designing anatase-based electrode with improved electrochemical performance for sodium-ions batteries. [Display omitted] • Pompon-villus shaped hydrogen titanate/anatase was prepared for the first time. • Heterostructure was constructed between hydrogen titanate and anatase. • As-obtained hydrogen titanate/anatase showed good electrochemical performances. [ABSTRACT FROM AUTHOR]

Recurrent Neural Network (RNN) is a typical feedback neural network, which is particularly effective in processing time-series data tasks such as image description, text generation and classification, etc. However, its safety and quality issues have aroused strong concern in academia and industry. One of the most commonly used methods to ensure RNN-driven software quality is testing and optimizing RNN. Its core idea is to introduce human efforts to label test cases so that many labeled test cases can be used to trigger faults in RNNs. But this brings a huge overhead. Therefore, it is of great importance to study the test case selection method for RNN. Current research on test case selection for RNN has achieved some results from the stateful view of RNN, but there are still some problems, such as a low bug detection rate, poor inclusiveness, and lack of diversity. In this paper, according to the structural characteristics of RNN, we propose a method of RNN test case selection, RNNtcs, which combines clustering and uncertainty, in order to select test cases that can touch RNN bugs as much as possible, thus reducing the cost of labeling. In order to evaluate RNNtcs, we conduct experiments on popular image datasets, text datasets and RNN models. The experimental results show that RNNtcs is superior to the state-of-the-art approach DeepState in bug detection effectiveness, bug detection inclusiveness and bug detection diversity. The test cases selected by RNNtcs can effectively improve the robustness of the RNN model. [ABSTRACT FROM AUTHOR]

A novel process to prepare titanium dioxide from Ti-bearing electric furnace slag by NH 4 HF 2 -HF leaching and hydrolyzing process has been developed. In this present study, the effects of [NH 4 + ]/[F] mXolar ratio, leaching temperature, [F] concentration, liquid/solid mass ratio, leaching time on the Ti extraction, and the phase transformations have been investigated to reveal the leaching mechanism of Ti-bearing electric furnace slag in NH 4 HF 2 -HF solution. In the NH 4 HF 2 -HF leaching process, the MgTi 2 O 5 and Al 2 TiO 5 are converted to TiF 6 2− and Mg-Al-bearing precipitate. Ti extraction rate reached 98.84% under the optimal conditions. In addition, 98.25% iron ions can be removed in the presence of NaCl prior to hydrolysis process. The effects of pH and temperature on the selective hydrolysis of TiF 6 2− during hydrolysis process were also studied. In the hydrolysis process, the TiF 6 2− is converted to (NH 4 ) 2 TiOF 4 . By calcination, high grade TiO 2 powder with its purity of 99.88% was obtained, using which the products, well crystallized anatase and rutile, were obtained through roasting at 800 °C and 1000 °C, respectively. [ABSTRACT FROM AUTHOR]

PAX are important regulators of developmental processes. PAX7 plays crucial roles in patterning of the dorsal central nervous system (CNS), neural crest (NC), and skeletal muscle. Here, we identified six spliced isoforms of pax7a and one pax7b and characterized their expression patterns. All of flounder Pax7a-1, Pax7a-2, Pax7a-3, and Pax7b contain a conserved paired domain (PD), an octapeptide motif (OP), and a paired type homeodomain (HD). However, the PD of Pax7a-4 and the HD of Pax7a-5 are not intact, and there is no HD in Pax7a-4 and Pax7a-6. pax7a and pax7b show distinct spatiotemporal expression patterns during embryogenesis. Whole-mount in situ hybridization demonstrates that the expression patterns of pax7a and pax7b are overlapping but distinguishable in the dorsal central nervous system. pax7a is expressed in most part of the brain and the neural tube, while pax7b is expressed exclusively in the diencephalon and the midbrain. In addition, pax7a is also expressed in the cranial NC and the trunk NC. RT-PCR results show that there were different expression patterns between the different isoforms. These results indicate subfunction partitioning of the duplicated pax7 genes. The duplicated pax7 may provide additional flexibility in fine-tuning neurogenesis and somitogenesis. [ABSTRACT FROM AUTHOR]