Search

Electronic correlation is of fundamental importance to high temperature superconductivity. While the low energy electronic states in cuprates are dominantly affected by correlation effects across the phase diagram, observation of correlation-driven changes in fermiology amongst the iron-based superconductors remains rare. Here we present experimental evidence for a correlation-driven reconstruction of the Fermi surface tuned independently by two orthogonal axes of temperature and Se/Te ratio in the iron chalcogenide family FeTe$_{1-x}$Se$_x$. We demonstrate that this reconstruction is driven by the de-hybridization of a strongly renormalized $d_{xy}$ orbital with the remaining itinerant iron 3$d$ orbitals in the emergence of an orbital-selective Mott phase. Our observations are further supported by our theoretical calculations to be salient spectroscopic signatures of such a non-thermal evolution from a strongly correlated metallic phase into an orbital-selective Mott phase in $d_{xy}$ as Se concentration is reduced., Comment: 25 pages, 5 figures, accepted version to appear in Communications Physics. arXiv admin note: text overlap with arXiv:2010.13913

Coacervate-based membraneless organelles with diverse functionality as well as the capability of mimicking intracellular physiological environments are attracting researchers' great interest. However, the further studies focusing on functionalized membranization of coacervate as a step toward an advanced membrane-bound protocell are still rare. In this study, we develop a way to compartmentalize coacervate based on reconstitution with a natural cellular wall, which could then serve as a promising chassis for the development of protocells with selective sequestration of various biomacromolecules. Significantly, the compartmentalized protocell could behave like a phagocyte and selectively capture, engulf, and then kill Escherichia coli efficiently. Taken together, our studies present a strategy for advancing coacervate-based protocell design as well as the development of smart materials with on-demand functionalization.

The idea of employing non-Abelian statistics for error-free quantum computing ignited interest in reports of topological surface superconductivity and Majorana zero modes (MZMs) in FeTe0.55Se0.45. However, the topological features and superconducting properties are not observed uniformly across the sample surface. The understanding and practical control of these electronic inhomogeneities present a prominent challenge for potential applications. Here, we combine neutron scattering, scanning angle-resolved photoemission spectroscopy, and microprobe composition and resistivity measurements to characterize the electronic state of Fe1+yTe1-xSex. We establish a phase diagram in which the superconductivity is observed only at sufficiently low Fe concentration, in association with distinct antiferromagnetic correlations, whereas the coexisting topological surface state occurs only at sufficiently high Te concentration. We find that FeTe0.55Se0.45 is located very close to both phase boundaries, which explains the inhomogeneity of superconducting and topological states. Our results demonstrate the compositional control required for use of topological MZMs in practical applications.

This paper will employ the transparent soil experiment technology to explore the influences of shallow necking on the vertical bearing capacity of single pile with cap. Model experiment is carried out on one intact pile and nine shallow necking piles. The load-settlement curves of all piles are obtained, which are used to study bearing characteristics of piles. The displacement fields of soil around piles are employed to investigate the reasons for the loss of vertical bearing capacity of piles with shallow necking. The vertical bearing capacity is greatly reduced which is caused by shallow necking. When the axial dimension of necking is the same, the larger the radial size is, the greater the loss of vertical bearing capacity is. When the radial dimension of necking is the same, the greater the axial size is, the greater the loss of vertical bearing capacity is. The soil near the pile shaft and under the pile cap produces a large area of vertical downward deformation, which causes the relative displacement between the pile shaft and the soil to greatly reduce. Therefore, it is easy that the necking piles with caps develop negative friction, which causes the vertical bearing capacity of piles to reduce. When the radial dimension of the shallow necking is 80% of pile diameter, the pile is easy to be damaged.

Lead halide perovskites exhibit structural instabilities and large atomic fluctuations thought to impact their optical and thermal properties, yet detailed structural and temporal correlations of their atomic motions remain poorly understood. Here, these correlations are resolved in CsPbBr3 crystals using momentum-resolved neutron and X-ray scattering measurements as a function of temperature, complemented with first-principles simulations. We uncover a striking network of diffuse scattering rods, arising from the liquid-like damping of low-energy Br-dominated phonons, reproduced in our simulations of the anharmonic phonon self-energy. These overdamped modes cover a continuum of wave vectors along the edges of the cubic Brillouin zone, corresponding to two-dimensional sheets of correlated rotations in real space, and could represent precursors to proposed two-dimensional polarons. Further, these motions directly impact the electronic gap edge states, linking soft anharmonic lattice dynamics and optoelectronic properties. These results provide insights into the highly unusual atomic dynamics of halide perovskites, relevant to further optimization of their optical and thermal properties. Neutron and X-ray scattering measurements provide further insight into the anharmonic behaviour of lead halide perovskites, revealing that rotations of PbBr6 octahedra in CsPbBr3 crystals occur in a correlated fashion along two-dimensional planes.

In this study, a novel pre-synthesized Bi–Sb–O phase was produced and doped into the ZnO– Bi2O3– Co2O3– MnO2 (ZBCM)- based varistor to make an improvement in nonlinear coefficient (α) and a decrease in breakdown voltage (E1mA). Results showed that the ZBCM- Bi–Sb–O ceramics can be well sintered with high sintering density above 0.98 of the ZnO theoretical density at a low sintering temperature of 900 °C. A large average grain size (d) of 6.89 μm was obtained in the ZBCM – 3 wt% Bi–Sb–O varistor, which leads to a low E1mA of 235.0 V/mm. At the same time, the α increases to 53.0 due to the improved barrier height (ϕb) of 1.85 eV. Furthermore, the lowest dielectric loss (tanδ) at low frequency as well as the increased grain resistance (Rg) made the smallest leakage current density (IL) of 0.005 μA mm−2 in the same Bi–Sb–O doping content. Besides, a considerable low E1mA of 168.91 V/mm with a mildly α of 37.4 was obtained in the ZBCM– 1 wt% Bi–Sb–O varistor. Hopefully, this novel research provided a new strategy to prepare low-voltage ZnO– Bi2O3- based varistors at low sintering temperature.

Understanding the interaction of ionized two-dimensional (2D) graphene oxide (GO) nanosheets at the air–water interface can improve the self-assembly framework of GO sheets. Herein, the potential o...

The spontaneous self-assembly of multicellular ensembles into living materials with synergistic structure and function remains a considerable challenge in biotechnology and synthetic biology. Here, we exploit the aqueous two-phase separation of dextran-in-PEG emulsion micro-droplets for the capture, spatial organization and immobilization of algal cells or algal/bacterial cell communities to produce discrete multicellular spheroids capable of both aerobic (oxygen producing) and hypoxic (hydrogen producing) photosynthesis in daylight under air. We show that localized oxygen depletion results in hydrogen production from the core of the algal microscale reactor, and demonstrate that enhanced levels of hydrogen evolution can be achieved synergistically by spontaneously enclosing the photosynthetic cells within a shell of bacterial cells undergoing aerobic respiration. Our results highlight a promising droplet-based environmentally benign approach to dispersible photosynthetic microbial micro-reactors comprising segregated cellular micro-niches with dual functionality, and provide a step towards photobiological hydrogen production under aerobic conditions., The development of techniques capable of orchestrating the assembly of living cells into multicellular ensembles with synergistic and function is challenge. Here, the authors construct algal or algal/bacterial cells-based core shell-like structure based on aqueous two-phase system for synergic photosynthetic H2 production.

The quality of in situ data is key to calculating resistance factor of bored piles. However, it is difficult to summarize accuracy data due to various uncertainties in engineering. This paper employs the Bayesian method and mathematical statistics theory to put forward an estimation method for updating in situ data. A testing database (33 tests in noncohesive soils and 53 tests in cohesive soils) of bored piles is summarized. The model factor of bored piles is quantified as the ratio of the measured capacity to the calculated capacity. The proposed method is used to classify summarized data into three categories, which are “good data,” “general data,” and “bad data.” The “bad data” are discarded because of bad contribution to calculation, and Bayesian theory is incorporated into updating the model factor statistics. Three methods are used to calculate the reliability index and resistance factor of bored piles, and the results show that the reliability index and resistance factor are sensitive to the quality of data. Finally, the available values of resistance factors are proposed based on resistance factor design for bridge design specification, which can offer references to revision relevant specifications. The proposed method can be used to update other geotechnical data.

Many compute-intensive network applications such as application-layer traffic generator, Deep Packet Inspection(DPI) and web servers are widely deployed on commodity PC for the reason of flexibility and cheap price. However, how to improve their performance on general purpose OS is challenging due to the high packet I/O related overheads. This paper presents PacketUsher, a high-performance packets processing framework to remove these performance bottlenecks. In building PacketUsher, we constructed a DPDK wrapper as the underlying packet I/O engine to accelerate packet transmission, and utilized the strategies of zero copy, batch processing and parallelism to improve packet processing. Through RFC2544 benchmark, we demonstrate that DPDK wrapper has excellent packets transmission capability. As a case study of PacketUsher, we design and implement a commercial application-layer traffic generator. The experiment results show that the FPS (Flow Per Second) value of our traffic generator over PacketUsher is more than 4 times of that over standard Linux platform. By comparison, the FPS value over PacketUsher is about 3 times of that over existing methods (Netmap and PF_RING).

The manipulation of physicochemical and biological properties of the encapsulated cells by cell surface engineering technique is now attracting more and more researchers’ interest. In this study, we showed a mild and highly efficient way to build a type of polymer-living cell conjugates based on photoinduced electron transfer-reversible addition-fragmentation chain-transfer polymerization (PET-RAFT). The polymerization could proceed at room temperature under the blue light initiating and showed very less influence on the activity of the living cells. Significantly, the constructed positively charged polymer-living cell conjugates could aggregate with the negatively charged native Chlorella pyrenoidosa (CP) cell to form a microscale aggregate which then allowed a functionality switching of the encapsulated CP cells from the normal photosynthetic O2 towards H2 production with an average rate of 0.26 μmol H2h−1 (mg chlorophyll)−1 for 42 h. It is then anticipated that the method we show could contribute an effective way for generating different functionalized living cell-polymer hybrid structures on demand, and the demonstrated aggregation-induced functionality switching of the CP cells is also anticipated to inspire more applications of the cell-based materials towards biology green energy.

We show by counterexample that the binary integer quadratic programming model proposed by Kaabi and Harrath [2019. “Scheduling on Uniform Parallel Machines with Periodic Unavailability Constraints....

Nanofluidics in two-dimensional (2-D) heterogeneous layered materials with hybrid overlapping structures exhibit promising potential in filtration and separation applications. However, molecular transport across the heterogeneous interlayer galleries remains largely unexplored, in particular, there exists disputation in the function and performance of hybrid graphene oxide (GO)-based laminate membrane for the water transport. Herein, heterogeneous 2-D GO-based nanochannels were employed as a typical platform to investigate the water flow by nonequilibrium molecular dynamics (MD) simulation. It is demonstrated that both heterogeneous and homogeneous GO nanochannels exhibit similar reduced water flow behavior, even if one surface of the 2-D channel is the pristine graphene. In particular, the flow rate in the hybrid GO/pristine graphene nanochannels does not lie between those of the oxidized and the pristine regions, and the high-friction GO surface suppresses the water transport and controls the entire flow performance. This result is qualitatively consistent with the recent experimental observation. By comparing with the MD simulation, a hydrodynamic model was developed to describe the flow rate for 2-D heterogeneous nanochannels. The reduced water transport has been revealed as the distinct vertical dragging effect, arising from the synergistic effect between the interfacial affinity from GO surfaces and the interlayer molecular interaction. Our results provide novel physical pictures for the molecular transport inside heterogeneous 2-D nanochannels.

Controllable protein adsorption on solids is of great importance in many modern technological applications. The role of the water phase in mediating the protein-surface interactions, however, still remains poorly understood. Herein, we employ free energy calculations to systematically explore the mechanisms of the surface adsorption/bioresistance correlating with the interfacial water layers. The studied peptide shows strong binding affinity with the hydrophobic surface, as illustrated by a monotonic decrease in the free energy profile with no energy barriers. However, the surface bioresistance could be triggered in two distinct ways, by not only an enhancement of the surface-water interactions, but also increased interactions between the water and adsorbates. The enhanced surface-water interactions decrease the tendency of the surface dehydration and the subsequent adsorbate penetration into the surface-bound water layers, thus leading to the surface bioresistance. On the other hand, the enhanced water-adsorbate interactions could promote water stabilization of the adsorbate in the bulk solution, effectively preventing the peptide adsorption. Our results further elucidate that the increase in the peptide size favors its adsorption on the hydrophobic surface, but go against the adsorption on the hydrophilic surface. The mechanisms revealed here may facilitate the design of novel proteins/peptides, materials, and solvents for a controllable adsorption at a solid-water interface.

In this paper, (1-x)K0.5Na0.5NbO3-x mol% In2O3 (abbreviated as KNN-xIn) lead-free piezoelectric ceramics were prepared using conventional solid sintering method. The effects of In2O3 on the phase structure, microstructure, domain evolution, electrical properties, fatigue behavior and thermal stability of KNN ceramic matrix were systematically studied. XRD results show that all the ceramics possess the orthorhombic phase with domain architectures presented in the PFM. The addition of In2O3 improved the fatigue resistance owing to the enhanced density. The temperature stability of the 1.0 mol% In2O3 doped sample was significantly improved. It was found that the KNN ceramics with 1.0 mol% In2O3 addition exhibited good electrical properties (d33* = 179 pm/V, d33 = 103 pC/N, TC = 388 °C, Pr = 31.52 μC/cm2, er = 327, tanδ = 3.28%). The results suggested that this material should be an attractive lead-free material for piezoelectric applications.

New chiral bisboronic receptors based on pyrene-excimer were synthesized and applied for the determination of absolute configuration and enantiomeric composition of tartaric acid. The distinction was visualized by portable UV lamp in certain concentration range. There were three ways for the sensors to enantioselectively recognize tartaric acid, including the fluorescence spectrum, UV–vis spectrum, and CD spectrum. The enantiomeric excess of tartaric acid was measured quantitatively by using fluorescence analytical technique. Compared with the previous chiral boronic acid sensors, sensor 1 showed weaker background fluorescence and excellent chiral recognition ability of D/ l -tartaric acid throughout the whole pH range.

The water contamination by 2,4-dichlorophenol (2,4-DCP) is a tough environmental problem, so its removal has aroused much attention recently. In this study, the synthesis of a β-cyclodextrin-based submicron polymeric particles (CSPs) is described along with its utilization as adsorbent for the remediation of 2,4-dichlorophenol (2,4-DCP) from aqueous solution. Morphology and structural characterization illustrated the microstructure evolution of the aggregated CSPs with different catalytic doses. Using CSPs obtained under optimum conditions as sorbent, the adsorption performance for 2,4-DCP was systematically studied. The adsorption process fitted well the pseudo-second-order model and the Freundlich model, and thermodynamic studies manifested that the adsorption was a spontaneous and exothermic process. The slightly acidic and neutral pH as well as inorganic ions co-existence were found to be favorable for adsorption of 2,4-DCP onto CSPs. Further, CSPs had superior affinity for 2,4-DCP from aqueous media containing other analogues (2-chlorophenol and phenol). The comprehensive analysis of experimental and theoretical results suggested that the π–π, hydrophobic, and hydrogen bonding interactions may jointly drive the uptake process of 2,4-DCP. Thus, CSPs even with low surface-area showed high adsorption capacity for 2,4-DCP compared with activated carbon and other adsorbents. Also, CSPs displayed excellent structural stability and reversibility after 5 cycles of adsorption experiments. Considering the simple fabrication method employed, excellent 2,4-DCP adsorption capacity, remarkable structural stability, and reusability, CSPs provided an alternative platform for the remediation of 2,4-DCP from aqueous solution.

Graphyne is expected to be a new-class of highly-efficient sieving membranes due to its controllable uniform pore structure and ultrathin single-atom thickness. Herein, we computationally investigate the permeation performance of liquid ethanol–water mixtures across polyporous two-dimensional γ-graphyne sheets. It was found that, in the mixture, ethanol with larger molecular diameter permeates faster through the graphyne pores than water. The simulations demonstrate that pristine graphynes could act as highly-efficient ethanol-permselective membranes for separation of ethanol–water mixtures, with ethanol permeability remarkably higher than conventional membranes. This separation mechanism is distinctly different from the molecular-size dependent sieving process. The stronger hydrophobic interfacial affinity between graphyne and ethanol makes ethanol molecules preferentially adsorb on graphyne surface and selectively penetrate through graphyne pores. This penetration mechanism provides new understanding of molecular transport through atomically thick two-dimensional nanoporous membranes and this work is expected to be valuable in the potential development of highly-efficient membranes for liquid-phase mixture separation.

The involvement of prenucleation clusters (PNCs) in crystallization from a supersaturated solution has been recently admitted within the framework of nonclassical nucleation theory; however, little is known about PNCs, at the quantitative level, for their formation mechanism and stability, the new phase formed by them, as well as their impact on nucleation barriers. Herein, using the sophisticated free energy calculations with a cumulative simulation time of over 5 μs, we identify a thermodynamically favored pathway of the PNC-mediated nucleation for calcium phosphate, starting with the ion pair association in solution. We demonstrate that such an ion association occurs not only between cations and anions, but also for the polyatomic species with charges of the same sign, which, in fact, leads to PNC formation via the consecutive coordination of the phosphate ions to calcium. The free energy decomposition calculations illustrate that the water phase is capable to either hinder or promote ion association for the abovementioned processes, and its specific role is intricately related to the characteristics of the hydration shell around calcium ions. The favorable interactions between the highly charged species play a crucial role in stabilizing the PNC complexes and the aggregates formed by PNCs. Furthermore, our present work reveals that the uptake of an extra calcium ion is the first and mandatory step to trigger PNC aggregation into amorphous calcium phosphate (ACP) by eliminating the related free energy barriers. Our theoretical study successfully provides quantitative explanations to a large set of experimental data in the field, which is currently under intense discussions associated with the nonclassical nucleation mechanism. The combination of computational methods developed in our present work offers a feasible and general solution to quantitatively and systematically study ion associations and crystal nucleation/growth in an aqueous solution at the atomic level, which are normally inaccessible to most of the existing experimental acquisitions.

Hybrid layered double hydroxides (LDHs)/graphene oxide (GO) nanocomposites are novel two-dimensional (2-D) materials applied in extensive fields, which take advantages of the synergistic effect of ...

The design of improved materials for orthopedic implants and bone tissue engineering scaffolds relies on materials mimicking the properties of bone. Calcium phosphate (Ca-PO4)-mineralized collagen fibrils arranged in a characteristic hierarchical structure constitute the building blocks of mineralized vertebrate tissues and control their biomechanical and biochemical properties. Large, flexible, acidic noncollagenous proteins (ANCPs) have been shown to influence collagen mineralization but little is known about mineralization mechanisms with the aid of small proteins. Osteocalcin (OCN) is a small, highly structured biomolecule known as a multifunctional hormone in its undercarboxylated form. Here, we examined the potential mechanism of collagen intrafibrillar mineralization in vitro mediated by OCN as a model protein. Rapid and random extrafibrillar mineralization of flakey Ca-PO4 particles was observed by transmission electron microscopy mainly on the outer surfaces of collagen fibrils of a preformed collagen scaffold in the absence of the protein. In contrast, the protein stabilized hydrated, spherical nanoclusters of Ca-PO4 on the outer surface of the fibrils, thereby retarding extrafibrillar mineralization. The nanoclusters then infiltrated the fibrils resulting in intrafibrillar mineralization with HAP crystals aligned with the fibrils. This mechanism is similar to that observed for unstructured ANCPs. Results of fibrillogenesis and immunogold labeling studies showed that OCN was associated primarily with the fibrils, consistent with ex vivo studies on mineralizing turkey tendon. The present findings contribute to expanding our understanding of collagen intrafibrillar mineralization and provide insight into design synthetic macromolecular matrices for orthopedic implants and bone regeneration.

Supply chain management as an indispensable component in intelligent city construction has faced great opportunities with the fast development of AI, Internet of Things, big data and mobile communication. Blockchain, as a heated and promising area, features some key characteristics that make it an optimal solution to problems in traditional supply chain management and can also act as a great platform to these cutting-edge technologies. In this paper, a design scheme of integrated platform for information service provided by participants in supply chain and based on Ethereum blockchain is proposed. System architecture and smart contracts are designed to guarantee the security enhancement from blockchain can be fully exploited. Some common and vital problems in the blockchain-based scheme are also discussed and solved, among which a data-driven credit evaluation scheme workable on chain is put forward and a cross-chain architecture is designed to make the system more secure, intelligent and scalable.

We present a neutron-scattering study of phonons in single crystals of (Pb0.5Sn0.5)(1-x)InxTe with x = 0 (metallic, but nonsuperconducting) and x = 0.2 (nonmetallic normal state, but superconducting). We map the phonon dispersions (more completely for x = 0) and find general consistency with theoretical calculations, except for the transverse and longitudinal optical (LO) modes at the Brillouin-zone center. At low temperature, both modes are strongly damped but sit at a finite energy (approximate to 4meV in both samples), shifting to higher energy at room temperature. These modes are soft due to a proximate structural instability driven by the sensitivity of Pb-Te and Sn-Te p-orbital hybridization to off-center displacements of the metal atoms. The impact of the soft optical modes on the low-energy acoustic modes is inferred from the low thermal conductivity, especially at low temperature. Given that the strongest electron-phonon coupling is predicted for the LO mode, which should be similar for both studied compositions, it is intriguing that only the In-doped crystal is superconducting. In addition, we observe elastic diffuse (Huang) scattering that is qualitatively explained by the difference in Pb-Te and Sn-Te bond lengths within the lattice of randomly distributed Pb and Sn sites. We also confirm the presence of anomalous diffuse low-energy atomic vibrations that we speculatively attribute to local fluctuations of individual Pb atoms between off-center sites.

Inspired by the compartmentalized structure of cells, self-regulating responsive hollow microcapsules are highly desirable for the modulation of enzymatic reactions. Here, we report a strategy to fabricate gold nanorod embedded proteinosomes by covalently grafting gold nanorods onto the surface of proteinosomes. The excellent photothermal conversion efficiency of the embedded gold nanorod and the thermal phase transition of the grafted PNIPAAm allow the constructed hybrid proteinosomes to show reversible contraction behaviors triggered by near-infrared light with the molecular weight cutoff of the membrane decreased to ca. 50 kDa, and importantly, the contraction frequency of the constructed proteinosomes could be as fast as 1 min and last for at least 15 cycles. Subsequently, the effective encapsulation of three cascade enzymes into the proteinosomes realizes the construction of a near-infrared responsive microreactor that allows control of the cascade reaction by near-infrared illumination, thereby enabling reversible on and off of the enzymatic reaction. Such microcapsule-based reactors demonstrate the potential to alter the membrane molecular weight cutoff, and it is believed that the development of such responsive microcapsules will have great potential for studying cellular responses and provide a platform for future applications in biosensing and drug delivery.

Although protein adsorption at the solid-water interface is of immense importance, understanding the crucial role of the water phase in mediating protein-surface interactions is lacking, particularly due to the lack of fundamental thermodynamic data. Herein, we have performed complicated free energy calculations and successfully extracted the entropy and enthalpy changes of molecular adsorption on solids. Using the gold and graphene as the surface models with distinct affinities to the water phase, we successfully unravel the sharply opposite manners of entropy-enthalpy compensation in driving water and tripeptide adsorptions on two surfaces. Though the thermodynamic features of water adsorption on surface are enthalpically dominated based on the positions of free energy barriers and minima, the favorable entropy term significantly decreases the free energy barrier and further stabilizes the adsorbate at the adsorption site on the graphene surface. For the peptide, the shape of the adsorption free energy profile is jointly determined by the enthalpy and entropy changes, which, however, alternatively act the driving force to promote the peptide adsorption on the Au surface and graphene surface. The distinct structural and dynamic properties of solid-liquid interfaces account for the special role of the interfacial water phase in regulating the competitive relationship between the entropy and enthalpy variations.

Potato is a major food crop with enormous biomass straw, but lignocellulose recalcitrance causes a costly bioethanol conversion. Here, we selected the cytochimera (Cyt) potato samples showing significantly-modified lignocellulose and much increased soluble sugars and starch by 2–4 folds in mature straws. Under two pretreatments (8 min liquid hot water; 5% CaO) at minimized conditions, the potato Cyt straw showed complete enzymatic saccharification. Further performing yeast fermentation with all hexoses released from soluble sugars, starch and lignocellulose in the Cyt straw, this study achieved a maximum bioethanol yield of 24 % (% dry matter), being higher than those of other bioenergy crops as previously reported. Hence, this study has proposed a novel mechanism model on the reduction of major lignocellulose recalcitrance and regulation of carbon assimilation to achieve cost-effective bioethanol production under optimal pretreatments. This work also provides a sustainable strategy for utilization of potato straws with minimum waste release.

We report experimental studies of a series of BaFe2S3-x Se x (0 ⩽ x ⩽ 3) single crystals and powder specimens using x-ray diffraction, neutron-diffraction, muon-spin-relaxation, and electrical transport measurements. A structural transformation from Cmcm (BaFe2S3) to Pnma (BaFe2Se3) was identified around x = 0.7 - 1. Neutron-diffraction measurements on the samples with x = 0.2, 0.4, and 0.7 reveal that the Neel temperature of the stripe antiferromagnetic order is gradually suppressed from ~120 to 85 K, while the magnitude of the ordered Fe2+ moments shows very little variation. Similarly, the block antiferromagnetic order in BaFe2Se3 remains robust for 1.5 ⩽ x ⩽ 3 with negligible variation in the ordered moment and a slight decrease of the Neel temperature from 250 K (x = 3) to 225 K (x = 1.5). The sample with x = 1 near the Cmcm and Pnma border shows coexisting, two-dimensional, short-range stripe- and block-type antiferromagnetic correlations. The system remains insulating for all x, but the thermal activation gap shows an abrupt increase when traversing the boundary from the Cmcm stripe phase to the Pnma block phase. The results demonstrate that the crystal structure, magnetic order, and electronic properties are strongly coupled in the BaFe2S3-x Se x system.

The pollution of antibiotics in aquaculture environment is increasingly serious, and excessive antibiotics will kill the probiotics in aquaculture feed. How to improve the viability of probiotics in the antibiotics-contaminated environment is of significance. In this study, a new strategy for protecting Saccharomyces cerevisiae cells in situ against antibiotics is constructed based on cell surface engineering technology by putting on wearable protective layers for cells. The protective layer is constructed around cellular surface via the self-assembly of coacervate microdroplets that consist of carboxymethyl chitosan and carboxyl dextran. Without affecting the cell viability, the protective layer can grasp ciprofloxacin and decrease the contact of ciprofloxacin to cells and consequently improve the survival rate of cells when exposing to ciprofloxacin. This work highlights a facile strategy to establish removable artificial cell wall by biodegradable polysaccharides for improving the productivity of probiotics in antibiotic environments.

We report on the evolution of the average and depth-dependent magnetic order in thin-film samples of biaxially stressed and electron-doped EuTiO3 for samples across a doping range < 0.1 to 7.8 × 1020 cm-3. Under an applied in-plane magnetic field, the G-type antiferromagnetic ground state undergoes a continuous spin-flop phase transition into in-plane, field-polarized ferromagnetism. The critical field for ferromagnetism slightly decreases with an increasing number of free carriers, yet the field evolution of the spin-flop transition is qualitatively similar across the doping range. Unexpectedly, we observe interfacial ferromagnetism with saturated Eu2+ moments at the substrate interface at low fields preceding ferromagnetic saturation throughout the bulk of the degenerate semiconductor film. We discuss the implications of these findings for the unusual magnetotransport properties of this compound.

This work presents $$\hbox {Bi}_{{2}}\hbox {O}_{\mathrm {3}}\hbox {-doped SnO}_{{2}}$$ ceramic varistors prepared through conventional ceramic processing in the sintering temperature range of 1290–1320°C. The sample sintered at 1300°C exhibits a breakdown electric field as low as 11.6 V $$\hbox {mm}^{\mathrm {-1}}$$ . Scanning electron microscopy images reveal that all the samples have a compact structure, and energy dispersive spectroscopy results for the sample sintered at 1300°C indicate that Bi distributes homogeneously along the grain boundaries and aggregates inhomogeneously on the grain surfaces. With increasing sintering temperature, the grain boundary barrier height remains nearly constant at 0.80 eV. In both the dielectric loss and electric modulus spectra of the sample sintered at 1300°C, obvious relaxations were observed and the activation energies obtained from the respective spectra were 0.33 and 0.15 eV, which are expected to be related to oxygen vacancies and interstitial ions, respectively. Complex impedance spectra are employed to develop a non-typical equivalent circuit model for the $$\hbox {Bi}_{{2}}\hbox {O}_{\mathrm {3}}\hbox {-doped SnO}_{{2}}$$ ceramic varistors at low voltage that yields an excellent fit to the data.

We report neutron diffraction studies of FeS single crystals obtained from Rb(x)Fe(2−y)S(2) single crystals via a hydrothermal method. While no [Formula: see text] iron vacancy order or block antiferromagnetic order typical of Rb(x)Fe(2−y)S(2) is found in our samples, we observe C-type short-range antiferromagnetic order with moments pointed along the c axis hosted by a different phase of FeS with an expanded interlayer spacing. The Néel temperature for this magnetic order is determined to be 170 ± 4 K. Our finding of a variant FeS structure hosting this C-type antiferromagnetic order demonstrates that the known FeS phase synthesized in this method is in the vicinity of a magnetically ordered ground state, providing insights into understanding a variety of phenomena observed in FeS and the related FeSe(1−x)S(x) iron chalcogenide system.

The physical properties and mechanical characteristics of storage materials are significantly different from those of ordinary solids and liquids. The distribution of dynamic wall pressure during silo discharge is quite complicated. Considering the nonlinear relationship between the factors which affect the dynamic lateral pressure of silos, a prediction method of dynamic wall pressure for silos based on support vector machine (SVM) is proposed here, and furthermore, the modified grid search method (GSM) is incorporated in obtaining the optimal support vector machine parameters to improve the accuracy of the prediction. Comparing the results of the proposed prediction model with the results of experiment methods and simulation methods, it can be found that the SVM prediction model shows high accuracy and high generalization ability, and the prediction results of the model fit well with the results of experiment and simulation methods. The proposed method can provide reference for the prediction of the dynamic wall pressure of silos.

Highly epitaxial 0.755(Bi0.5Na0.5)TiO3-0.065BaTiO3-0.18SrTiO3 (BNT-BT-ST) ferroelectric films with (100), (110) and (111) orientations were fabricated on Nb doped SrTiO3 (N-ST) substrates. Three patterns of microstructure morphologies are observed in the epitaxial thin films. The superior ferroelectric with remanent polarization Pr of 18 µC/cm2 is obtained in (100) oriented thin film. The excellent dielectric properties with highest dielectric constant (1170) and tunability (68%) exhibit in the (111) oriented thin films. Both of the ferroelectric and dielectric properties in the epitaxial BNT-BT-ST films are more remarkable than those of the polycrystalline BNT-BT-ST film. The results should be ascribed to the orientated microstructure and ferroelectric-to-relaxor transition observed in the epitaxial BNT-BT-ST thin films. Strong orientation dependences of microstructure and electric properties are due to the relative alignment of crystallites and anisotropic polarization rotation. This study provides an insight into how to utilize orientation to regulate the structure and properties of epitaxial thin films.

This paper proposes a new second-order cone programming (SOCP) relaxation for convex quadratic programs with linear complementarity constraints. The new SOCP relaxation is derived by exploiting the technique that two positive semidefinite matrices can be simultaneously diagonalizable, and is proved to be at least as tight as the classical SOCP relaxation and virtually it can be tighter. We also prove that the proposed SOCP relaxation is equivalent to the semidefinite programming (SDP) relaxation when the objective function is strictly convex. Then an effective branch-and-bound algorithm is designed to find a global optimal solution. Numerical experiments indicate that the proposed SOCP relaxation based branch-and-bound algorithm spends less computing time than the SDP relaxation based branch-and-bound algorithm on condition that the rank of the quadratic objective function is large. The superiority is highlighted when solving the strictly convex quadratic program with linear complementarity constraints.

Ferroelectric Bi3.25La0.75Ti3O12 (BLT) thin films were deposited on Pt(111)/Ti/SiO2/Si substrates at 400 °C using rf-magnetron sputtering method. The microstructures were studied by X-ray diffraction, scanning electron microscopy and energy dispersive spectrometer. The as-deposited thin film is amorphous, while transformed to microcrystalline and well crystalline states after annealing at 650 °C and 750 °C, respectively. After annealing at 750 °C, the polycrystalline BLT thin film showed plated-like grains all with (117)-preferred orientation. Analyses of ferroelectric properties indicated that, comparing with the as-deposited thin film, the highly (117)-oriented crystalline thin film exhibited well-saturated hysteresis loops with a superior remnant polarization (2Pr) of 30.7 μC/cm2.

The adsorption of ions on a graphene surface is very important to control relevant graphene-based processes. In this work, a multiscale simulation was carried out to study the adsorption of Na+ /Cl- ions on graphene by combining quantum mechanics calculations and molecular dynamics (MD) simulations. The interaction energies of the ions with graphene were computed using density functional theory (DFT). It was found that the ions show strong interaction with a graphene cluster and the overwhelming portion of the interaction energy is the ion-π orbital interaction. The large orbital interaction can be ascribed to the two contributions arising from the ion-induced polarization of graphene and the charge transfer between ion and graphene. Their different contribution degrees reveal that the polarization effect plays a main role on the orbital interaction for ion adsorption. Comparatively, for Na/Cl atom adsorption, the charge transfer shows large part to the orbital interaction with weak atom-induced polarization. The obtained interaction energies were applied to develop new interaction potentials between ion and graphene, and then MD simulations were used to study the interfacial adsorption behavior of Na+ /Cl- aqueous solution onto the graphene surface. Due to enhanced ion-π interactions, Na+ /Cl- cooperatively demonstrates a strong ion adsorption layer through direct contact with the hydrophobic graphene surface. Our simulation result presents a new understanding of ion-graphene interactions.

Lead-free perovskite (Bi0.5Na0.5)0.935−xPrxBa0.065Ti1−xSbxO3 (BNBT6.5–xPS) ceramics are prepared by ordinary sintering technique. The compositional dependence of phase structure, electrical and photoluminescence properties of the ceramics was systematically investigated. Results showed that all samples exhibit pure perovskite structure with dense microstructures. With the addition of PS, a strong red emission located at 610 nm and a weak red emission at 660 nm under a light 450 nm excitation was observed. The strong red emission band is ascribed to the inter-4f transition from the excited 1D2 to the ground state 3H4 and the weak red emission located at 660 nm is due to the 3P0 → 3F2 transition. And then the BNBT6.5–0.004PS ceramic exhibited the strongest photoluminescence property. Besides the excellent photoluminescence properties, PS modifications induced an enhanced filed-induced strain. At x = 0.001, a large strain of 0.31% was obtained at a driving field of 70 kV/cm. As a multifunctional material, it has potential application as a multifunctional device such as optical-electro integration and coupling device applications.

Understanding the molecular mechanism of protein adsorption on solids is critical to their applications in materials synthesis and tissue engineering. Although the water phase at the surface/water interface has been recognized as three types: bulk water, intermediate water phase and surface-bound water layers, the roles of the water and surface in determining the protein adsorption are not clearly identified, particularly at the quantitative level. Herein, we provide a methodology involving the combination of microsecond strengthen sampling simulation and force integration to quantitatively characterize the water-induced contribution and the peptide-surface interactions into the adsorption free energy. Using hydroxyapatite and graphene surfaces as examples, we demonstrate how the distinct interfacial features dominate the delicate force balance between these two thermodynamics parameters, leading to surface preference/resistance to peptide adsorption. Specifically, the water layer provides sustained repelling force against peptide adsorption, as indicated by a monotonic increase in the water-induced free energy profile, whereas the contribution from the surface-peptide interactions is thermodynamically favorable to peptide adsorptions. More importantly, the revealed adsorption mechanism is critically dictated by the distribution of water phase, which plays a crucial role in establishing the force balance between the interactions of the peptide with the water layer and the surface. For the HAP surface, the charged peptide exhibits strong binding affinity to the surface, due to the controlling contribution of peptide-surface interaction in the intermediate water phase. The surface-bound water layers are observed as the origin of bioresistance of solid surfaces toward the adsorption of charge-neutral peptides. The preferred peptide adsorption on the graphene, however, is dominated by the surface-induced component at the water layers adjacent to the surface. Our results further elucidate that the intermediate water phase significantly shortens the effective range of the surface dispersion force, in contrast to the observation on the hydrophilic surface.

This paper proposes an experimental approach for monitoring and inspection of the formation accuracy in ultra-precision grinding (UPG) with respect to the chatter vibration. Two factors related to the grinding progress, the grinding speed of grinding wheel and spindle, and the oil pressure of the hydrostatic bearing are taken into account to determining the accuracy. In the meantime, a mathematical model of the radius deviation caused by the micro vibration is also established and applied in the experiments. The results show that the accuracy is sensitive to the vibration and the forming accuracy is much improved with proper processing parameters. It is found that the accuracy of aspheric surface can be less than 4 μm when the grinding speed is 1400 r/min and the wheel speed is 100 r/min with the oil pressure being 1.1 MPa.

In this work, molecular dynamics simulations were employed to study the permeation of ethanol-water mixtures through single-layer graphene oxide (GO) nanopores functionalized with COOH (carboxyl) and COO- (ionized carboxyl) groups. GO-COOH nanopore shows regular behavior with competitive permeation between the two species in the mixture. However, GO-COO- pore exhibits selective permeation of water, suggesting COO- functionalized GO sheets could provide the initial barrier to block ethanol permeation and enhance dehydration separation in GO-based membranes. Our simulation presents the underlying mechanism of the selective water transport is not determined by the pore-size sieving, but has been ascribed as the strong molecular affinity between water and GO-COO- surface. This interfacial interaction can induce the preferential interfacial adsorption and pore occupation for water, simultaneously impede the transport path of ethanol into the nanopore, and consequently give rise to the selective penetration of water in the mixture. The simulation results provide the direct theoretical evidence that ionization of carboxyl groups on GO sheets can be applied to improve the dehydration permeation of alcohol-water mixtures across GO-based separation membranes.

Much effort has been exerted to unravel the bone biomineralization mechanism by which the growth of plate-shaped crystals of hydroxyapatite (HAP) is regulated within a fibrillar collagen matrix. Acidic noncollagenous acidic proteins (NCPs) bearing a large number of carboxylate and phosphorylate amino acid residues are effective regulators of HAP crystal morphology. To reveal the energetic and structural essence of the growth-regulation mechanism, we performed here advanced molecular dynamics simulations to obtain adsorption free energies of side chain analogues (SCAs) of acidic and uncharged polar amino acids as well as the corresponding zwitterionic backbone (BB) fragment and compared the results to those for the entire amino acid molecule. We observed that negatively charged SCAs (phosphoserine in two protonation states, aspartate and glutamate) and the zwitterionic BB preferentially bind to the HAP (100) surface compared to the (001) face, consistent with [100] being the preferred growth direction for ...

The interaction between graphene oxide (GO) in solvent is a fundamental basis in its colloidal suspensible stabilization, which is important in the solution processing technique for the preparation of processable graphene sheets. In this work, the potential of mean force (PMF) between two GO nanosheets in solvents was simulated to quantify the interaction mechanism. It was observed that GO sheets in water with various oxidization levels demonstrate diverse interacting performances. The neutral GO sheets generally show weak attractive interaction with kinetic reversible aggregating/dispersing stability. However, the deprotonated GO sheets with negative charges have strong colloidal stability, which is due to the long-range electrostatic repulsion arising from the charged functional groups. The interaction of GO sheets is a delicate balance of the interacting force between GOs themselves and the corresponding solvation force. The detailed PMF analysis identifies the distinct roles of water in the contributi...

The variations of XRD full width at half maximum (FWHM), residual stress and hardness for the surface of GCr15 steel after triple shot peening (TSP) as a function of annealing time and temperature are studied. The results show that with the increase of annealing temperature and time, hardness and FWHM increase gradually while compressive residual stress (CRS) decreases gradually. CRS and micro- structure work together on the hardness values, and the micro-structure is the most important factor for hardness. According to establishing the quantitive relationship of hardness with FWHM and CRS, the value of hardness can be calculated; a new type of noncontact and nondestructive hardness testing can be realized by XRD method.

A ditopic zwitterionic Schiff base modified silica gel adsorbent SG-H 2 L 2 was prepared and it was characterized by Fourier transform infrared spectroscopy, elemental analysis, solid state NMR, thermogravimetry and porous structure analysis. SG-H 2 L 2 could simultaneously adsorb metal ions and attendant anions from the aqueous solution of metal salts . SG-H 2 L 2 exhibited a cooperative effect between the adsorption of metal cations and the attendant anions, and the adsorption efficiency decreased in the order MSO 4 > M(NO 3 ) 2 > MCl 2 (M = Cu, Co, Ni, Mn, Cd). SG-H 2 L 2 displayed good adsorption selectivity for Cu(II) and SO 4 2− from the aqueous solutions containing mixed metal ions of Cu(II), Co(II), Ni(II), Mn(II) and Cd(II) or mixed anions of SO 4 2− , NO 3 − , and Cl − . The preliminary mechanism for simultaneous and selective adsorption of the metal ions and attendant anions were discussed. The effect of different parameters including pH, contact time and initial concentrations of Cu(II) and SO 4 2− on the simultaneous adsorption of Cu(II) and SO 4 2− ions were investigated. The efficient adsorption of Cu(II) and SO 4 2− could be achieved in neutral pH region and the maximum adsorption capacities for Cu(II) and SO 4 2− , respectively, were the same of 0.42 mmol g −1 at 25 °C. The adsorption isotherms for Cu(II) and SO 4 2− fitted well with Langmuir model, while their adsorption kinetics followed the pseudo-second order model. Regeneration of SG-H 2 L 2 was realized by adjusting the solution pH with diluted H 2 SO 4 and ammonia solution, respectively. SG-H 2 L 2 exhibited good recyclability and reusability for four cycles use without deterioration in its functionality. SG-H 2 L 2 was also applied in different water samples and good recoveries and the selective adsorption of Cu(II) and SO 4 2− were achieved. This study provides a new bifunctional adsorbent which may be used for the effective removal of Cu(II) and SO 4 2− from water effluents containing mixed metal ions and anions.

Piezoelectrics have shown great potential for controlling the piezoelectro-optical process in multifunctional materials. Electric field poling is an effective way of modulating the structure of rare earth doped piezoelectric materials, thus affecting their piezoelectro–optical interplays. Here, the (Ba0.96Ca0.04)(Ti0.90Sn0.10)O3-0.2%Sm (BCST-Sm) lead-free ceramics exhibit high piezoelectric properties (d33 = 450 pC N−1, kp = 52%) as well as strong reddish-orange photoluminescence emission (PLE). The highest piezoelectric coefficient and PLE quenching of the BCST-Sm ceramics are obtained simultaneously at a poling electric field of 20 kV cm−1, which are related to the phase transition and the changes in lattice symmetry and domain structure. The BCST-Sm ceramics transform from the coexisting R–T phases to a single T phase by applying an electric field, where the long-range ordered large domain structure is induced. The decreased asymmetry and relaxor and the increased domain size contributed to the quenching of photoluminescence (PL) performance, while the instability of the polarization state and domain reorientation benefitted the piezoelectric response. This work demonstrates the inherent piezoelectro–optical interplays in association with various structures stimulated by the electric field and provides a physical mechanism for better understanding and designing multifunctional materials.

The nanoscopic structural and thermodynamic basis of biomolecule-regulated assembly and crystallization of inorganic solids have a tremendous impact on the rational design of novel functional nanomaterials, but are concealed by many difficulties in molecular-level characterization. Here we demonstrate that the free energy calculation approach, enabled by combining advanced molecular simulation techniques, can unravel the structural and energetic mechanisms of protein-mediated inorganic solid nucleation. It is observed that osteocalcin (OCN), an important non-collagenous protein involved in regulating bone formation, promotes the growth of nanosized calcium phosphate (CaP) ion clusters from a supersaturated solution. Free energy calculation by umbrella sampling indicates that this effect by OCN is prominent at the scale of 1 to 3 nm ion-association complexes (IACs). The binding interactions between gamma-carboxyl glutamate and the C-terminal and, interestingly, the arginine side chains of OCN and IACs stabilize under-coordinated IACs, thus promoting their growth. The promoter effect of OCN on the enlargement and further aggregation of IACs into cluster assemblies of tens of nm are confirmed by conventional molecular dynamics simulation and dynamic light scattering experiments. To the best of our knowledge, this is the first time that the free energy landscape of the early stages of CaP nucleation is shown. The free energy change as a function of IAC size shares the feature of decreasing monotonically as shown previously for the calcium carbonate system. Therefore, the nucleation of both these major biominerals apparently involves an initial phase of liquid-like ionic aggregates. The structural and thermodynamic information regarding OCN-CaP interactions amplifies the current understanding of biomineralization mechanisms at the nanoscale, with general relevance to biomolecule-tuned fabrication of inorganic materials.

The introduction of various organic acids during gypsum (CaSO4·2H2O) crystallization could change the crystallization behavior of gypsum leading to different macroscopic properties. Understanding the origin of organic acids in gypsum crystallization at an atomic level is the key step for us to rationalize the design of gypsum-related products. Here, citric acid (CA) and L-(+)-tartaric acid (LTA) were selected as two model compounds to investigate such organic–inorganic interactions. CA has the stronger retarding effect of gypsum precipitation as compared with LTA. The introduction of CA in aqueous solution results in the formation of a final plate-like gypsum crystal with a smaller specific surface area. However, the presence of LTA does not change the gypsum crystal morphology and the specific surface area remains almost the same as that of pure gypsum. AFM was firstly used to characterize the surface roughness of the gypsum (010) plane, and it was found that only a monolayer organic–inorganic structure is formed on top of the gypsum (010) plane for both LTA and CA. Afterwards, synchrotron μ-FTIR was utilized to obtain the atomic structure information, and the results further confirm that a mono-tartrate structure is formed. Finally, advanced metadynamics simulation (MD) was employed to obtain detailed organic–inorganic structure information and the free energy landscape. The simulation results show that CA has a stronger affinity as compared with LTA. CA and LTA were found to prefer a stand up conformation on top of the gypsum (010) plane. The combination of numerous characterization techniques with MD simulations, for the first time, clarifies the organic–inorganic interfacial structure in the gypsum system.

Lead-free ceramics, SrBi2Nb2O9–xBi2O3 (SBN–xBi), with different Bi contents of which the molar ratio, n(Sr) : n(Bi) : n(Nb), is 1 : 2(1 + x/2) : 2 (x = −0.05, 0.0, 0.05, 0.10), were prepared by conventional solid-state reaction method. The effect of excess bismuth on the crystal structure, microstructure and electrical properties of the ceramics were investigated. A layered perovskite structure without any detectable secondary phase and plate-like morphologies of the grains were clearly observed in all samples. The value of the activation energy suggested that the defects in samples could be related to oxygen vacancies. Excellent electrical properties (e.g., d33 = 18 pC N−1, 2Pr = 17.8 μC cm−2, ρrd = 96.4% and Tc = 420 °C) were simultaneously obtained in the ceramic where x = 0.05. Thermal annealing studies indicated the SBN–xBi ceramics system possessed stable piezoelectric properties, demonstrating that the samples could be promising candidates for high-temperature applications.

Lead-free (Ba1−xCax)(Ti0.95Hf0.05)O3 (x = 0.04–0.14) (BCHT) ceramics with good piezoelectric properties were successfully prepared using solid state reaction method. The structural and electrical properties of the BCHT ceramics were systematically studied. The polymorphic phase transitions (PPT) from orthorhombic phase to tetragonal phase shifts towards low temperature with increasing Ca contents, and the PPT can be obtained at room temperature (RT) in the composition range of 0.08–0.10 for the BCHT ceramics. The tetragonality of the BCHT ceramics at PPT is increased after poling treatment as depicted in the XRD patterns and Raman spectroscopy. The BCHT ceramics at x = 0.08 exhibit good piezoelectric properties (d33 = 380 pC/N, kp = 50% and Smax = 0.19% under the applied electric field of 50 kV/cm) and ferroelectric property (Pr = 13.4 μC/cm2), due to the coexistence of tetragonal phase and orthorhombic phase. The aging rate of d33 values from 20 °C to 90 °C is lower than 20% in this work, indicating that the BCHT ceramics have good temperature stability. The high piezoelectric properties with good temperature stability indicate that the BCHT ceramics are promising candidates as lead-free piezoelectric ceramics.

Ho 3+ -modified SrBi 4 Ti 4 O 15 ceramics with bright green light emission and enhanced electrical properties were fabricated by a conventional solid-state reaction method. Upon visible light irradiation, samples exhibit a strong green emission located at 546 nm and a weak red emission at 653 nm. These two emissions corresponding to the intra f - f transition from the excited state 5 S 2 to the ground state 5 I 8 and the 5 F 5 → 5 I 8 transition of Ho 3+ , respectively. The relative intensity of green and red emissions is related to the Ho 3+ contents closely, due to the concentration quenching effect. Moreover, it is also found that Ho 3+ doping significantly enhanced the electrical properties. At x = 0.008, samples exhibit optimal electrical properties and excellent piezoelectric temperature stability for the SBT- x Ho system. These results reveal that these materials have good application prospect in future optical temperature sensors by integrating its luminescent and piezoelectric properties.