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A theoretical model to predict the water permeability of nano-reinforced cement pastes from the pore structure (including the pore size distribution, pore interconnection, porosity and microcracks) is presented. The model is based on the general effective media (GEM) theory and multifractals, considering both the bridging of microcracks and capillary pores and the filling of nano gel pores of cement pastes reinforced with nano-admixtures. To validate the model, water permeability experiments were conducted using a cementitious composite reinforced with graphene oxide and multi-walled carbon nanotubes. The calculated results showed good agreement with the experimental measurements, with a decrease in the maximum error from 67.8% to 9.7% compared with the previously proposed GEM theory. Moreover, the theoretical calculations suggest that the reinforcing roles of nano-admixtures in cement paste to improve permeability-related properties may be mainly due to bridging effects in microcracks and capillary pores, rather than the filling of nano gel pores. The findings of this study enrich understanding of the mechanism of reinforcing cement-based materials with nano-admixtures. In addition, the permeability of cementitious composites can be measured directly, rather than the use if other using time-consuming methods.

Designer biosurfactants can be used to stabilise and functionalise interfaces. One particularly promising use is the stabilisation of oil-in-water emulsions, enabling fine tuning physical, chemical and biological surface properties. The ability of emulsion systems to carry high payloads makes them attractive for applications in medicine, food and fragrances, and cosmetics. However, they have limited long-term stability. Here we sought to use the metal ion-chelating ability of the biosurfactant peptide, AM1, to precipitate the formation of a gold metal shell on AM1-stabilised emulsions by electroless plating. We found that replacing the commonly used zinc(II) with palladium(II) for coordination by histidine residues of adjacent AM1 peptides produced interfacial films that maintained elasticity at acidic pH. Proton NMR suggested a coordination mechanism independent of the imidazole ring of the histidines. Nevertheless. stabilisation of emulsions at low pH enabled the deposition of a gold shell, albeit by an unexpected mechanism. We propose that gold nanoparticles forming in bulk are adsorbed onto the peptide-stabilised interface, accumulating into a particulate coating. The resulting one-step method for nanoparticle precipitation and shell formation will be useful for the creation of biocompatible core-shell particles for applications where large payloads of hydrophobic active compounds require stability over long time periods.

Portable and sensitive mixed-potential type solid-state electrolyte (MPSE) gas sensors can detect exhaled biomarkers in a noninvasive and inexpensive way, which is significant for convenient disease diagnosis and saving medical resources. However, high working temperature is still one of the main bottlenecks for hindering MPSE gas sensors' applications in disease diagnosis. Here, we, for the first time, developed and fabricated new room-temperature MPSE gas sensors utilizing K2Fe4O7 electrolyte and Ni/Fe-MOF (Ni/Fe clusters are coordinated with 1,4-H2BDC) sensing electrodes (SEs) for the detection of ppb-level NO. Among different MOF SEs, the sensor attached with the Ni-MOF SE presents the highest NO sensitivities. This is attributed to a reducing oxygen reduction reaction activity and enhancing NO electrochemical catalytic reaction activity, verified by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests. In addition, the presented sensor also shows a low detection limit (20 ppb), fast response/recovery characteristic (17 s/6 s to 50 ppb NO), excellent selectivity, acceptable repeatability, and long-term stability of 34 days to NO at 25 °C and 60%RH. Simultaneously, the mechanism of humidity effect on the sensing performance was investigated by EIS and CV tests. Our work provides new insight into the development of room-temperature solid-state electrolyte gas sensors based on the mixed-potential mechanism and enlarges the potential application domain.

The yielding segment of the core plate is surrounded by the restraining member, making it difficult to directly inspect the buckling-restrained brace (BRB) after earthquakes. A new BRB, of which the core plate can be directly inspected without disassembling the BRB, is proposed. Only the edge of the core plate is restrained. The simulation models are verified based on previous tests, and the influence of the key parameters on the performance of the partially restrained buckling-restrained brace (PBRB) is compared based on 22 models. The design recommendation for PBRB is summarized. The main conclusions are as follows: The increase of the weak-axis gap d between the core plate and the restraining member can decrease the hysteretic energy-dissipation capacity and increase the weak-axis deformation of the core plate. The weak-axis deformation f of the core plate is selected as the performance evaluation criteria of PBRB, and it is recommended to be controlled within the core plate thickness t. When the unrestrained width-to-thickness ratio bu/t is constant, the change of the maximum weak-axis bulging deformation fmax with the core plate thickness t is not obvious. To ensure that the new PBRB shows satisfied ductility after one strong earthquake and no damage after three strong earthquakes, the two performance levels and corresponding evaluation criteria are proposed, and the design recommendation for key parameters unrestrained width-to-thickness ratio (bu/t) and restrained width-to-thickness (b-bu)/t are given.

The low thermal conductivity and poor shape stability of phase change materials (PCMs) have seriously restricted their applications in energy storage and energy saving. In this paper, poly(ethylene glycol)–calcium chloride/carbon/carbon fiber felt (PEG-CaCl2/CCF) PCMs were fabricated by a liquid-phase impregnation–vacuum drying–hot compression molding method with carbon/carbon fiber felt as the three-dimensional (3D) thermal skeleton and PEG-CaCl2 as the polymer PCM matrix. PCMs were heated and compressed by the compression confinement method to improve the contact area between 3D skeleton carbon fibers. The carbon fibers in PCMs presented a 3D (X–Y–Z) network structure and the fiber arrangement was anisotropic, which were beneficial to improve the thermal conductivity of PCMs in the fiber direction. The compression confinement can improve the contact area between the fibers in the 3D skeleton. As a result, the thermal conductivity of PEG-CaCl2/CCF PCMs can reach 3.35 W/(m K) (in-plane) and 1.94 W/(m K) (through-plane), about 985 and 571% of that of PEG-CaCl2, respectively. Due to the complexation of PEG and CaCl2 and the 3D skeleton support of carbon fiber felt, PCMs have excellent shape stability. The paper may provide some suggestions for the preparation of high thermal conductivity and excellent shape stability PCMs.

Improving the electrical conductivity is an important role in realizing high thermoelectric performance of solution-processable polymers. Herein, a simple and robust approach to boost the mobility and doping efficiency of a diketopyrrolopyrrole-based copolymer with the introduction of thermocleavable side chains (PDPPS-X, where X is the molar ratio of the thermocleavable side chains and alkyl chains) is first provided. Notably, the incorporated thermocleavable groups can be effectively removed after thermal treatment and therefore contribute to the crystalline domain formation via hydrogen-bonded networks, which is critical for conductivity enhancements. Grazing incidence wide-angle X-ray scattering (GIWAXS) patterns give a clear indication that the thermal treatment of PDPPS-5 can greatly improve the structural arrangement, resulting in a significantly enhanced hole mobility (5.4 times that of PDPPS-0 without thermocleavable chains). Compared to PDPPS-0, a larger Fermi level shift is observed after doping PDPPS-5 with FeCl3, reflecting a better doping efficiency. Consequently, remarkably improved conductivity and power factor are achieved by PDPPS-5 after doping with 0.03 M FeCl3 at room temperature, which are about 2.2 and 3.5 times higher than that of PDPPS-0 at the same testing condition, respectively. Moreover, PDPPS-5 achieved a maximum power factor of 57.5 μW m-1 K-2 at 404 K.

Viscosity is one of the important thermophysical properties of liquid aluminum alloys, which influences the characteristics of mold filling and solidification and thus the quality of castings. In this study, 315 sets of experimental viscosity data collected from the literatures were used to develop the viscosity prediction model. Back-propagation (BP) neural network method was adopted, with the melt temperature and mass contents of Al, Si, Fe, Cu, Mn, Mg and Zn solutes as the model input, and the viscosity value as the model output. To improve the model accuracy, the influence of different training algorithms and the number of hidden neurons was studied. The initial weight and bias values were also optimized using genetic algorithm, which considerably improve the model accuracy. The average relative error between the predicted and experimental data is less than 5%, confirming that the optimal model has high prediction accuracy and reliability. The predictions by our model for temperature- and solute content-dependent viscosity of pure Al and binary Al alloys are in very good agreement with the experimental results in the literature, indicating that the developed model has a good prediction accuracy.

Fatigue crack growth (FCG) behavior of 9Cr/CrMoV dissimilar welded joint at elevated temperature and different stress ratios was investigated. Attention was paid to the region near the fusion line of 9Cr where carbon-enriched zone (CEZ) and carbon-depleted zone (CDZ) formed due to carbon migration during the welding process. Hard and brittle tempered martensite dominated the stress ratio-insensitive FCG behavior in the coarse grain zone (CGZ) of 9Cr-HAZ. For crack near the CGZ–CEZ interface, crack deflection through the CEZ and into the CDZ was observed, accompanied by an accelerating FCG rate. Compared with the severe plastic deformation near the secondary crack in 9Cr-CGZ, the electron back-scattered diffraction analysis showed less deformation and lower resistance in the direction toward the brittle CEZ, which resulted in the transverse deflection. In spite of the plastic feature in CDZ revealed by fracture morphology, the less carbides due to carbon migration led to lower strength and weaker FCG resistance property in this region. In conclusion, the plasticity deterioration in CEZ and strength loss in CDZ accounted for the FCG path deflection and FCG rate acceleration, respectively, which aggravated the worst FCG resistance property of 9Cr-HAZ in the dissimilar welded joint.

This paper primarily investigated the effect of fiber breakage defects on tensile properties of the unidirectional composite (UD) using the numerical simulation method. Different kinds of fiber breakage defects were firstly proved to exist in the UD according to the sub-micro computed tomography images at the microscale level. A strict random uniform distribution hypothesis was then proposed to introduce fiber breakage defects into the composite. Numerous microstructural models within random fiber breakage defects were created with the Monte Carlo method to analyze the fiber breakage defect effect on the UD. The results show that the tensile modulus of the UD was reduced by 17% when the fiber breakage defect volume fraction was only 1%, which indicates the effect of this kind of defect was very significant. The fiber volume fraction, defect volume fraction and property all have influences on the decrease of the UD caused by the fiber breakage defect. Finally, we derived a mathematical model to calculate the tensile modulus of the UD based on the numerical results. The proposed mathematical model has an application on the prediction of the axial modulus of the UD or the fiber tow containing large numbers of fiber breakage defects in the composites with complicated structure.

Two series of symmetric LC dimers with the same rigid group and different fluorine terminal group (F and F3C) have been synthesised by varying the length of flexible spacers, termed 1 F series (1 F...

As one of the most effective energy storage compounds, phase change materials (PCMS) play an important role in energy conservation and storage. However, the inherent poor thermal conductivity and l...

In this paper, scanning electron microscope (SEM) tests and 3D scanning technologies were adopted to investigate the creep failure mechanism of sandy mudstone from a micromesoscopic view. The SEM test results showed that the fracture surface micromorphology of the specimens that suffered creep loading was more fractured and rougher. It was also found by the fractal analysis of the SEM microscopic images that the fractal dimensions of the creep failure specimens were larger than those of the uniaxial compression failure, indicating that the creep damage increased the irregularity and a larger degree of roughness fluctuation. The 3D scanning technologies combining with the 3D reconstruction methods proved that the crack expansion path of crept specimens was more complicated, showing a more prominent asperity height and slope angle. Finally, a mesostrain dilating microelement model of the sandy mudstone specimen’s fracture surface was proposed to prove that the dilatancy effect would be more pronounced in the creep process.

CeO2 decorated CoOx rod-like hybrid, supported onto holey reduced graphene (CoOx/CeO2/RGO) composite, was fabricated via a surfactant-assisted route. Its corresponding electrocatalytic performance towards oxygen reduction/evolution reactions (ORR and OER) was systematically investigated in alkaline electrolyte. Structural, morphological and compositional studies revealed changes in electronic and surface properties when CeO2 was introduced as an oxygen buffer material. The oxygen vacancies effectively enhanced the electrocatalytic activity, while the synergistic effect of co-catalyst CeO2, CoOx active-centers, and defective graphene with many voids facilitate the charge/mass transfer, making CoOx/CeO2/RGO an efficient and stable bifunctional electrocatalyst for OER/ORR with ΔE = 0.76 V (ΔE = E10 mA cm-2, OER – E1/2, ORR). This parameter is 70 mV and 270 mV lower than CoOx/RGO and the benchmark Pt/C, respectively. In addition, the OER/ORR bifunctionality of CoOx/CeO2/RGO composite outperforms that of Pt/C catalyst in a H2-O2 micro fuel cell platform.

Membrane plays a central role in molecule separation and selection. However, most artificial membranes utilise a fixed passage size and only effective for limited molecule types. Here, via a large series of molecular and first-principles calculations, we reveal the potential of graphene kirigami (GK), a novel structure with nanoscale incisions on one-atom-thick graphene, which can transform into a three-dimensional structure under deformation, as an ultra-membrane for highly adjustable molecule selection and the practical fabrication feasibility of GK-like membranes using a novel selective tearing process on initially defected graphene. Facilitated by the high stretchability of GK-based membranes, we demonstrate a wide range of gas selection capability on a single membrane. The interaction energy of adsorbed gas molecule also shows that the unique geometry of the pores on GK enables a new adsorption channelling mechanism that enhances molecular separation. Compared with nanoporous graphene, the dynamic gas penetration test shows that various GK membranes are capable of 30 times higher pore-size adjustability and up to 1.5–3.4 times higher gas separation rate. The GK ultra-membrane opens new venues for numerous applications in CO2 capture and storage, water desalination, wastewater treatment, hazardous waste containment system, chemical processing, bionics, and pharmaceutical and medical devices.

It remains a conundrum to reconcile the contradiction between effective tumor retention and deep intratumor infiltration for nanotherapeutics due to the sophisticated drug delivery journey. Herein, we reported an acid-sensitive supramolecular nanoassemblies (DCD SNs) based on the multivalent host-gest inclusions of two polymer conjugates for conquering diverse physiological blockages and amplifying therapeutic efficacy. The multiple inclusions of repetitive units on the hydrophilic polymer backbone reinforced the binding affinity and induced robust self-assembly, ameliorating instability of the self-assemblies and facilitating to prolong the drug retention time. By virtue of the acid-sensitive Schiff base linkages, the supramolecular nanoassembly could respond to the unique tumor microenvironment (TME), dissociate, and transform into smaller particles (∼30 nm), thereby efficiently traversing the complicated extracellular matrix and irregular blood vessels to achieve deep intratumor infiltration. The acid-sensitive DCD SNs can absorb a large number of protons in the acidic lysosomal environment, causing the proton sponge effect, which was conducive to their escape from endolysosomes and accelerated lysosomal disruption, so that the active chemotherapeutic doxorubicin (DOX) could enter the nucleus well and exert severe DNA damage to induce apoptosis. This versatile supramolecular nanoplatform is anticipated to be a promising candidate to overcome the limitations of insufficient stability within the circulation and weak intratumor penetration.

The molecular arrangement in the lubricating film will affect the friction coefficient. When using liquid crystal as a lubricant, various methods can be tried to adjust the arrangement of the liqui...

Recently presented as a rapid and eco-friendly manufacturing method for thermoset polymers and composites, frontal polymerization (FP) experiences thermo-chemical instabilities under certain conditions, leading to visible patterns and spatially dependent material properties. Through numerical analyses and experiments, we demonstrate how the front velocity, temperature, and instability in the frontal polymerization of cyclooctadiene are affected by the presence of poly(caprolactone) microparticles homogeneously mixed with the resin. The phase transformation associated with the melting of the microparticles absorbs some of the exothermic reaction energy generated by the FP, reduces the amplitude and order of the thermal instabilities, and suppresses the front velocity and temperatures. Experimental measurements validate predictions of the dependence of the front velocity and temperature on the microparticle volume fraction provided by the proposed homogenized reaction-diffusion model.

The rapid and accurate detection of hydrogen peroxide (H2O2) has recently been a fascinating research topic in electrochemical sensing. Herein, spinel CuMn2O4 nanoflakes were synthesized through coprecipitation and pyrolysis methods and then drop-coated onto the surface of a bare glassy carbon electrode (GCE), successfully generating an enzymatic-free electrochemical sensor (CuMn2O4/GCE) for good amperometric detection ability of H2O2. In comparison with the reported spinel AB2O4-based electrocatalysts in a phosphate buffer solution, the CuMn2O4/GCE sensor exhibits a high sensitivity of 3.420 A M–1 cm–2 and a low detection limit of 12 nM. This excellent sensing performance is mainly derived from the inherent porous structure and the large electrochemical active area of spinel CuMn2O4 nanoflakes, as well as the synergistic effect between Cu and Mn that facilitates electron transfer and increases active sites. Especially, the high contents of Cu+ and Mn3+ ions in the nanocatalyst are useful for promoting the capture and reduction of trace H2O2. In addition, the CuMn2O4/GCE sensor presents a satisfactory recovery in monitoring H2O2 derived from rat serum, commercial milk, and disinfectors, indicating its potential applications in related environmental, food, and biological fields.

Critical heat flux (CHF) is an important heat transfer deterioration phenomenon during boiling heat transfer. It has been extensively studied, especially in the field of nuclear energy. Previous re...

Silica refractory has excellent high-temperature performance, but its apparent porosity is relatively high. In this work, samples obtained before and after creep testing of silica brick (1550 °C, 50 h), from used silica checker brick (existing only tridymite and amorphous) and from used dome brick (existing only cristobalite and amorphous) were investigated using a three-dimensional structure model based on X-ray computed tomography (CT). The results show that the porosity of silica brick was high but consisted mainly of interconnected pores, with a very small proportion of closed pores (smaller after long-term use). During the use of silica brick, the morphology and phase transformation caused large particles to rupture, and the mineralizer became liquid at high temperature. The broken particles and interconnected pores provided channels for the migration of the liquid in the brick at high temperature. The silica brick presented a homogeneous ceramic structure during long-term operation. Tridymite or cristobalite presented a solid frame leading to an excellent creep performance of the silica brick (the creep rate of the checker brick was −0.16% at 1550 °C for 50 h). Results were discussed, compared with literature and a model for the transformation of the silica brick from a refractory structure to a homogeneous ceramic structure was established in this paper.

Sorption-enhanced-steam-reforming (SESR) is a thermochemical conversion technology that produces a high-purity hydrogen stream by utilizing in-situ removal of CO2 with a sorbent. In this paper, the advantages and disadvantages of CaO based sorbents, alkali-metal based sorbents (Na2ZrO3, Li2ZrO3 and Li4SiO4), hydrotalcite based sorbents, bifunctional materials and sorbents prepared from wastes are briefly discussed, and the techniques to improve the sorption properties of these CO2 sorbents are summarized. In the process of hydrogen production by sorption-enhanced-steam-reforming, the selection of suitable high-temperature CO2 sorbent is the key to produce high purity hydrogen. Furthermore, the hydrogen-production performance of the above-mentioned sorbents in the SESR process is investigated and summarized. Finally, a future perspective and some suggestions regarding these five types of sorbents are put forward.

The rational design of electrode architecture coupling with high specific capacity nanomaterials is highly desirable to build superior energy storage system. Herein, molybdenum-based compounds embedded in flexible 3D interconnected porous carbon nanofibers with protective porous carbon shell are constructed via a facile electro-blowing spinning technique using as free-standing lithium-ion battery (LIB) anodes. Such a well-designed architecture possesses large surface area, protective porous carbon shell and 3D interconnected porous structure. Moreover, various high specific capacity molybdenum-based compounds, including MoS2, MoO2 and MoN, can homogenously disperse within the fibers under different carbonization condition, especially, some of them are bridged to the fiber skeleton through a thin graphite carbon layer. The synergetic coupling effects benefited from the structural and material advantages are effective to provide more lithium-ion storage active sites, fast electrons/ions transfer pathways and good structural integrity. Using as free-standing anodes of LIB, the three fibrous anodes deliver an excellent electrochemical performance in terms of high specific capacity, superior rate capability and satisfied cycling stability. Extraordinarily, the well-designed architecture of fibrous anodes might open a new paradigm to boost the creation of high-performance electrodes for various energy storage devices.

Heat dissipation problem is the primary factor restricting the service life of an electronic component. The thermal conductivity of materials has become a bottleneck that hinders the development of the electronic information industry (such as light-emitting diodes, 5G mobile phones). Therefore, the research on improving the thermal conductivity of materials has a very important theoretical value and a practical application value. Whether the thermally conductive filler in polymer composites can form a highly thermal conductive pathway is a key issue at this stage. The carbon fiber/carbon felt (CF/C felt) prepared in the study has a three-dimensional continuous network structure. The nickel-coated carbon fiber/carbon felt (CF/C/Ni felt) was fabricated by an electroplating deposition method. Three-dimensional CF/C/Ni/epoxy composites were manufactured by vacuum-assisted liquid-phase impregnation. By forming connection points between the adjacent carbon fibers, the thermal conduction path inside the felt can be improved so as to improve the thermal conductivity of the CF/C/Ni/epoxy composite. The thermal conductivity of the CF/C/Ni/epoxy composite (in-plane K∥) is up to 2.13 W/(m K) with 14.0 wt % CF/C and 3.70 wt % Ni particles (60 min electroplating deposition). This paper provides a theoretical basis for the development of high thermal conductivity and high-performance composite materials urgently needed in industrial production and high-tech fields.

The AlSi10Mg alloy samples were prepared by laser selective melting technology, and the effects of laser power, scanning distance and powder thickness on the microstructure, density and mechanical properties of the formed AlSi10Mg alloy samples were studied. The results showed that the phases of the AlSi10Mg alloy formed by laser melting in the selected area are mainly α-Al matrix and eutectic Si; the forming parallel to the direction of the component forms a typical fish scale structure, which is formed after the laser scanning molten pool solidifies , Its growth direction is parallel to the direction of heat dissipation; as the laser energy density decreases, the height of the fish scale tissue decreases and the width increases; when the laser power is higher, the density of the formed sample is also higher; the laser power is 900W, The sample with a scanning distance of 0.09mm and a spreading thickness of 0.05mm has better performance. The tensile strength and elongation of the sample parallel to the component direction are 288MPa and 2.1%, respectively.

The all-inorganic nature of CsPbI3 perovskites allows to enhance stability in perovskite devices. Research efforts have led to improved stability of the black phase in CsPbI3 films; however, these strategies-including strain and doping-are based on organic-ligand-capped perovskites, which prevent perovskites from forming the close-packed quantum dot (QD) solids necessary to achieve high charge and thermal transport. We developed an inorganic ligand exchange that leads to CsPbI3 QD films with superior phase stability and increased thermal transport. The atomic-ligand-exchanged QD films, once mechanically coupled, exhibit improved phase stability, and we link this to distributing strain across the film. Operando measurements of the temperature of the LEDs indicate that KI-exchanged QD films exhibit increased thermal transport compared to controls that rely on organic ligands. The LEDs exhibit a maximum EQE of 23 % with an electroluminescence emission centered at 640 nm (FWHM: ≈31 nm). These red LEDs provide an operating half-lifetime of 10 h (luminance of 200 cd m-2 ) and an operating stability that is 6× higher than that of control devices.

Metal alloy nanosheets play a very important role as catalysts, which also show obvious advantages in the field of biosensor. Compared with traditional methods, such as enzyme method, gas chromatography or optical absorbance, the detection of ascorbic acid is simpler and more stable by spectroscopy. Ag–Cu alloy nanosheets with a thickness of about 1–3 nm and an average lateral size of 3–5 nm were synthesized in this study by the soft template method. These nanosheets were used to construct a sensor for measuring the concentration of ascorbic acid. The initial UV-Vis absorption peaks for the Ag–Cu alloy nanosheets in aqueous solution were effectively quenched upon addition of ascorbic acid. As the ascorbic acid concentration was in the range of 5–250 mmol/L changes, the UV absorbance intensity for the sensor also changed. Because of its wide detection range, high sensitivity, and excellent stability, the Ag–Cu alloy sensor method may be an excellent alternative to the traditional ascorbic acid measure method.

Organic matter (OM) and minerals are major particle components in lacustrine organic-rich shales. Their association and distribution control the development of the primary pore space. The response of OM-driven conduction by modifying the pore-space volume and structure in organic-rich shales of the virgin zone is still unclear. Based on a detailed study of geochemical, mineralogical, and geophysical properties from immature lacustrine oil-prone shales of the Songliao Basin (Northeast China), we have observed a novel continuous variation of electrical resistivity driven by large ranges of total-organic-carbon (TOC) content (0.64–24.51 wt%). The reduced resistivity at low TOC content ([Formula: see text]) and then enhanced resistivity at high TOC content ([Formula: see text]) are present in our immature shales. These variations in electrical resistivity are confirmed by fluid (S1) and solid organic compounds (S2). Furthermore, clay and detrital minerals in shales contribute to the variation of electrical resistivity as well as OMs at low and high TOC content. The electrical resistivity of shales is closely related to the pore-space volume and structure for the electrical flow pathway. Two resistivity trends are highlighted by pore parameters such as the pore volume, throat/pore ratio, pore diameter, and bulk density. Although reduced amounts and the arrangement of large pores for low TOC content cannot decrease the conduction, the enhanced additional clay conduction and low OM concentration reduce the resistivity of shales. Moreover, increased amounts of nonconductive fluid and solid organic compounds and the effect of OM filling on pore space during high TOC content enhance the resistivity of shales. Thus, modified minerals and pore space driven by various OMs affect the electrical resistivity of immature shales. These results improve the understanding of OM-driven conduction in shales and contribute to the evaluation of source rocks using a well-log method.

Three-dimensional characterization of defects in continuous casting blooms of a heavy rail steel with different electromagnetic stirring intensities at the solidification end, also named final electromagnetic stirring, was performed employing a laboratory-based X-ray computed tomography to evaluate the effect of final electromagnetic stirring on the internal quality of blooms. The three-dimensional distribution and morphology of defects including porosities and oxide inclusions in blooms were characterized. The amount, size and shape complexity of defects increased gradually from the loose-side surface to the center of blooms. The total volume fraction of defects was 5265 and 3942 ppm when the current of final electromagnetic stirring was 200 and 300 A, respectively. The sphericity of defects varied from 0.1 to 0.75, and the equivalent spherical diameter varied between 20 and 450 μm. Most defects with a sphericity > 0.6 were nearly spherical and were assumed to be oxide inclusions. The volume fraction of both porosities and inclusions was small in the chilled layer and the columnar crystal zone and then increased rapidly toward the equiaxed zone. Increasing the current of F-EMS from 200 to 300 A significantly decreased the volume fraction of porosities in the center of the bloom from 2906 to 1873 ppm. It could also decrease the volume fraction and average diameter of oxide inclusions in the bloom by reducing the number of large inclusions.

A large-capacity hydrogen storage system, which is also able to purify the hydrogen during storage, is appealing and bears significance for the mobile hydrogen use systems which require highly pure...

Doping of metals is highly effective in improving electrochemical performance of lithium iron phosphate. Here, based on a first-principles calculation result that Ru doping at the Fe sites has positive effects on promoting the ability of electron and Li+ transmission by reducing the lattice parameter and band gap, as well as the increase in Fermi energy, we constructed Ru-doped LiFe1-x Ru x PO4/C through the sol-gel preparation technology as cathode materials for Li-ion batteries. As a result, LFP-1 (x = 0.01) delivers excellent specific capacities of 162.6 and 110.6 mA h g-1 under 0.1 and 10 C, respectively. At the same time, LFP-1 emerges with excellent cycling performance, with a capacity retention of up to 95.6% after 300 cycles at 5 C. Ru doping is beneficial for improving the lithium diffusion coefficient and electrical conductivity, therefore strongly increasing electrochemical performance. This work represents a significant addition to exploring a new class of lithium iron phosphates with excellent performance in new energy storage and transition systems.

This brief presents a customized ac hybrid LED driver for high nominal range (220–240 VAC) applications using average current control. A fixed offset hysteretic window approach is proposed to reduce the switching frequency variation. In order to enable low-side current sensing, a special substrate connection is presented. The designed LED driver is fabricated with a 0.18- $\mu \text{m}$ , 700-V ultra-high voltage CMOS process. Measurement results show that under 230-VAC, 50 Hz input, the peak efficiency of the customized design is over 94% and the power factor is greater than 0.92 while suppressing the photometric flicker and delivering 17-watt power to the LEDs.

The grain surfaces (film surface and grain boundary) of polycrystalline perovskite films are vulnerable sites in solar cells since they pose a high defect density and initiate the degradation of perovskite absorber. Achieving simultaneously defect passivation and grain protection from moisture is crucial for the viability of perovskite solar cells. Here, an in situ cross-linked grain encapsulation (CLGE) strategy that improves both device stability and defect passivation is reported. Cross-linkable semiconducting small molecules are mixed into the antisolvent to uniformly form a compact and conducting cross-linked layer over the grain surfaces. This cross-linked coating layer not only passivates trap states and facilitates hole extraction, but also enhances the device stability by preventing moisture diffusion. Using the CLGE strategy, a high power conversion efficiency (PCE) of 22.7% is obtained in 1.55-eV bandgap planar perovskite solar cells. The unencapsulated devices with CLGE exhibit significantly enhanced device stability again moisture and maintain >90% of their initial PCE after shelf storage under ambient condition for over 10,000 h.

Materials research for advances in fusion technologies will depend an analytical sensitivity to Li, but appropriate nuclear reaction cross-sections are very poorly known. Here we determined the differential cross-sections for 7 Li ( 3 He , p 0 ~ 4 ) 9 Be , 7 Li ( 3 He , d 0 ) 8 Be and 6 Li ( 3 He , p 0 ) 8 Be from 1.2 to 3 MeV at a lab angle of 146 ° . All sources to the total combined standard uncertainty in the measurement were discussed in detail.

The inherent safety issues of commercial organic liquid electrolytes make it hard to deploy them in lithium metal batteries. By contrast, nanocomposite polymer electrolytes (NCPEs) can not only sup...

In view of the disadvantages of concentration polarization and trade-off effects in the application of membrane in desalination field, oxide-nano graphene oxide/polyamide (O-NGO/PA) loose intermediate layer and PA ultra-thin dense layer were introduced to fabricate PA/O-NGO/polyphenylene sulfide composite membrane with sandwich structure via multi-step interfacial polymerization (MS-IP) method. The selective permeation mechanism of ultrathin layer produced by different aqueous monomers (PIP and MPD) was studied, the effect of its physicochemical structure on the relief of concentration polarization phenomenon and the breakthrough of trade-off effect was analyzed. The ultra-thin and dense PA layer mainly played the role of interception and shortened the water molecular penetration path. In the retention test of metal salt solution, compared with the rough surface, it was found that the smooth surface was more conducive to the diffusion of intercepted metal ions into the feed solution, thus alleviating the concentration polarization phenomenon.

Heavy metal Cadmium (Cd) will continuously pollute the atmosphere, soil and various water environments through material circulation, and even pose a threat to human safety. It has been designated as a first-class pollutant in sewage by China, therefore there is an urgent need to find new, more effective, and low-cost method to accurately detect Cadmium ion (Cd2+) concentration. We experimentally prepared a new Cd2+ sensor based on NiS2 nanomaterials capable of measuring Cd2+ concentration. The corresponding relationship between over potential of NiS2 nanomaterials in H2SO4 electrolyte solutions with different Cd2+ concentration and reduction peak with change of Cd2+ concentration was obtained by electrochemical method.

An experimental study has been conducted to examine the effect of different concentrations of α-Al2O3 nanofluids on boiling heat transfer for downward facing heating. The experimental results indicated that the surface heat transfer was enhanced with the rise of the nanofluids concentration, due to the bubble generation rate and disturbance increased. For downward facing heating, bubbles were not able to escape since the bouncy force influenced, and the vapor film appeared earlier as the increase of bubble generation rate. However, the heat transfer coefficient remains at a relatively high value in the early stage of film boiling, which suppresses the deterioration of heat transfer, due to the influences of nanofluids. As the various concentrations of nanofluids increased from 0 g/L to 0.012 g/L, it was found that the enhancement of the CHF (critical heat flux) up to 20.5%. After the nanofluids boiling, the surface roughness decreased and the wettability became worse. From the experimental phenomena, under the influence of these two factors, the bubble activity was enhanced.

Rare-earth-doped up-converters with Yb3+ as a sensitizer show a high internal conversion efficiency under the excitation at wavelength λ = 980 nm. For the solar cell applications of up-converters, ...

Evaporation-based thin-film coating processes are ubiquitous in fields such as organic electronics, dye coatings, and the pharmaceutical industry. Based on experimental observations of enhanced thi...

Janus membrane with opposite wettability on its two sides has witnessed an explosion of interest in the field of liquid spontaneous and directional transport for their promising prospect. The advances in fabrication technology and natural bionics have brought remarkable progress for the development of Janus materials. Among the exciting progress, the micro/nanofabrication technique of electrospinning shows advantages in constructing thin porous fibrous membrane materials with controllable surface wettability and hierarchical structures. Here, a brief review of bioinspired Janus membrane for unidirectional liquid penetration fabricated by electrospinning is presented, and the underlying scientific mechanism is discussed with an emphasis on the materials design involving asymmetric surface wettability and micro-topology structure. An overview of recent emerging applications is also reviewed, with special attentions to liquid separation, water collection, distillation, and smart textile, etc. As researchers keep to develop more efficient strategies on designing new Janus membrane with higher performances, it has become increasingly important to understand the mechanism of liquid moving dynamics at the asymmetric interface in order to better recognize the scientific limitations currently hindering the field development. At last, the challenges currently faced and possible strategies on developing new Janus membranes for optimization and engineering in the future are proposed.

In this article, the nanoparticles of CoFe2O4 and FeS2/FeCoS2 have been generated by direct oxidation and sulfurization of Fe–Co precursor and used as counter electrode (CE) material for dye-sensitized solar cells (DSSCs). Compared with CoFe2O4, FeS2/FeCoS2 nanoparticles have superior electrical conductivity and catalytic activity. Furthermore, the introduction of reduced graphene oxide (RGO) improved the performance of FeS2/FeCoS2. By attaching FeS2/FeCoS2 nanoparticles to the surface of RGO, it alleviated the agglomeration of nanoparticles effectively. Meanwhile, the catalytic activity and electrical conductivity of FeS2/FeCoS2@RGO in DSSC are greatly improved. With increasing contact area, the penetration rate of the electrolyte is accelerated, which results in a faster reaction rate of tri-iodide that can be significantly accelerated. We explain the modification of FeS2/FeCoS2 nanoparticles by RGO through the morphology characterization and electrochemical performance test. The DSSCs assembled by FeS2/FeCoS2@RGO achieved a choiceness power conversion efficiency (PCE) of 7.84%, which is higher than those of CoFe2O4 nanoparticles (3.71%), FeS2/FeCoS2 nanoparticles (7.05%), and platinum (Pt) (7.54%).

Creep age forming technology (CAF) has been widely used to manufacture large integral panels in aerospace industry. However, due to the bending of the sheet metal, the stress states usually changes along the thickness direction during the CAF process, resulting in a complex distribution of stress. In addition, deformation texture is introduced when the sheet has a large pre-deformation, which also greatly affects the shape and performance of the component after aging. In this paper, the anisotropy in compression creep-ageing behavior of 2219-T3 aluminum alloy was studied. It was found that there is obvious anisotropy of compressive creep strains, the creep strain is the largest when the applied stress is along the rolling direction (RD) and the smallest when the applied stress is along the transverse direction (TD). The results of room temperature (25 ° C) and high temperature (165 ° C) tensile property test shows that the as-received material properties has obvious in-planar anisotropy, and the yield strength in the RD is the largest, but the 45° and TD are basically the same. Interestingly, the anisotropy of yield strength after SFA and compressive stress creep aging has basically disappeared, that is,the material properties tended to be isotropic after ageing.

In this work, a diffusion-theory-based model has been devised to simulate dissolution kinetics of a poorly water-soluble drug, ibuprofen. The model was developed from the Noyes-Whitney equation in which the dissolution rate term is a function of the remaining particulate surface area and the concentration gradient across the boundary layer. Other dissolution parameters include initial particle size, diffusion coefficient, material density, and diffusion boundary layer thickness. It is useful for predicting nonsink circumstances under which pure API polydisperse powders are suspended in a well-mixing tank. The model was used to compare the accuracy of simulations using spherical (single dimensional characteristic length) and cylindrical particle (multidimensional characteristic lengths) geometries, with and without size-dependent diffusion layer thickness. Experimental data was fitted to the model to obtain the diffusion layer thickness as well as used for model validation and prediction. The CSDs of postdissolution were also predicted with this model, demonstrating good agreement between theory and experiment.

The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.

Complex patterns integral to the structure and function of biological materials arise spontaneously during morphogenesis. In contrast, functional patterns in synthetic materials are typically created through multistep manufacturing processes, limiting accessibility to spatially varying materials systems. Here, we harness rapid reaction-thermal transport during frontal polymerization to drive the emergence of spatially varying patterns during the synthesis of engineering polymers. Tuning of the reaction kinetics and thermal transport enables internal feedback control over thermal gradients to spontaneously pattern morphological, chemical, optical, and mechanical properties of structural materials. We achieve patterned regions with two orders of magnitude change in modulus in poly(cyclooctadiene) and 20 °C change in glass transition temperature in poly(dicyclopentadiene). Our results suggest a facile route to patterned structural materials with complex microstructures without the need for masks, molds, or printers utilized in conventional manufacturing. Moreover, we envision that more sophisticated control of reaction-transport driven fronts may enable spontaneous growth of structures and patterns in synthetic materials, inaccessible by traditional manufacturing approaches., Competition between reaction and thermal transport during frontal polymerization drives the emergence of complex thermal profiles that are harnessed to spontaneously pattern material properties.

2195 Al-Li alloy is famous for high strength, excellent fatigue strength and good stress corrosion resistance, which is widely used in the manufacture of high-performance aerospace components. The aim of this study is to validate how the stress relaxation aging behavior effect on the mechanical properties of 2195 Al-Li alloy. Through mechanical property test, the research was found that the performance after stress relaxation aging is higher than artificial aging (AA). In addition, the analysis of scanning electron microscopy SEM and TEM revealed that dislocations should be introduced by the stress relaxation aging process, which is more conducive to the precipitation of the T1 phase and strengthened the material with prolong ageing time. The results show that stress relaxation aging can significantly promote the precipitation of the T1. Therefore, this paper sheds new light on how SRA can improve mechanical properties and that SRA make better improve the distribution of precipitates in the grain boundary.

This study focuses on evaluating the leachability of chromium in Electric-Arc-Furnace stainless-steel slag (EAFS) from the perspective of mineralogical control. Mineral-phase identification results showed that EAFS mainly comprised merwinite, magnetite, dicalcium silicate, calcium aluminosilicate, eskolaite, spinel, and perovskite. The chromium in the EAFS was mainly present in the Mg-Cr spinel, Fe-Cr alloy, or distributed in the form of oxide in the matrix phase, merwinite. When undergoing leaching, the leachate of the EAFS was alkaline and reducing, and a portion of the chromium in the slag was released into the leachate and existed mainly in a trivalent state. In the early stage of leaching, the rapid dissolution of chromium-bearing silicate minerals led to a rapid increase in the concentration of trivalent chromium. However, in the middle and late stages (> 15 days) of leaching, the chromium concentration reached stable values. The geochemical model of chromium leaching from the EAFS demonstrated that the simulated values of the chromium concentration were consistent with the batch-leaching test values. The primary phase Cr2O3 in the EAFS controlled the chromium concentration in the leachate. After entering the leachate, trivalent chromium could be presented as Cr(OH)4– because Cr(III)-hydroxide was unstable in the alkaline leachate.