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Controlling the magnetic anisotropy of ferromagnetic materials plays a key role in magnetic switching devices and spintronic applications. Examples of spin-orbit torque devices with different magnetic anisotropy geometries (in-plane or out-of-plane directions) have been demonstrated with novel magnetization switching mechanisms for extended device functionalities. Normally, the intrinsic magnetic anisotropy in ferromagnetic materials is unchanged within a fixed direction, and thus, it is difficult to realize multifunctionality devices. Therefore, continuous modulation of magnetic anisotropy in ferromagnetic materials is highly desired but remains challenging. Here, we demonstrate a gate-tunable magnetic anisotropy transition from out-of-plane to canted and finally to in-plane in layered Fe5GeTe2 by combining the measurements of the angle-dependent anomalous Hall effect and magneto-optical Kerr effect with quantitative Stoner-Wohlfarth analysis. The magnetic easy axis continuously rotates in a spin-flop pathway by gating or temperature modulation. Such observations offer a new avenue for exploring magnetization switching mechanisms and realizing new spintronic functionalities.

Prussian blue analogues are used in electrochemical deionization due to their cation sorption capabilities and ion selectivity properties. Elucidating the fundamental mechanisms underlying intercalation/deintercalation is important for the development of ion-selective electrodes. We examined the thermodynamic and kinetic properties of nickel hexacyanoferrate electrodes by studying different temperatures effects on intercalation/deintercalation with monovalent ions (Li

Lithium-ion battery (LIB) is the dominant energy storage device for the application on electric vehicles and portable electronic devices. Up to now, the enhancement of LIBs’ energy density mainly depends on the improvement of anode’s capacity. Due to the obstacle of large volume effect and low rate performance, the use of intrinsic high-capacity anodes, such as silicon, is still in the laboratory stage. Combining battery and capacitor to improve the electrochemical performance of the commercial carbon anode is an alternative and effective strategy in practical application. In this paper, a high nitrogen (N) content (8.2%) carbon is obtained by pyrolyzing the melamine formaldehyde (MF) foam resin at low temperature (600 °C). It delivers a stable specific capacity of around 600 mAh g−1 at 0.1C. No significant capacity degradation appears after 200 cycles, and the coulombic efficiency maintained over 99.5%. Even at 1.2 C, a specific capacity of 350 mAh g−1 is delivered and so a Li-ions diffusion coefficient of 1.8×10–13 cm2s-1. The reason of the superior electrochemical performance of the high N-doped carbon anode is the synergistic effect of battery and capacitor. The calculated pseudocapacitance proportion is from 32 to 61% at scan rate from 0.1 to 1mV s−1.

The core-void@shell architecture shows great advantages in enhancing cycling stability and high-rate performance of Si-based anodes. However, it is usually synthesized by template methods which are complex and environmentally unfriendly and would lead to low-efficiency charge and mass exchange because of the single-point van der Waals contact between the Si core and the shell. Here, a facile and benign one-step method to synthesize multi-Si-void@SiO

In the mixed matrix membrane (MMM), the interface between the filler and the polymer matrix will directly affect the gas separation performance of the membranes. Reasonable interfacial design in MMMs is thus important and necessary. In this work, metal-organic coordination interaction is used to construct the interface in metal-organic framework (MOF) nanosheet-based polyimide MMMs where ultrathin Co-benzenedicarboxylate MOF nanosheets (CBMNs) with a thickness less than 5 nm and a lateral size more than 5 μm are synthesized as fillers and a carboxyl-functionalized polyimide (6FDA-durene-DABA) is used as a polymer matrix. Because of the high aspect ratio (>1000) of CBMNs, abundant metal-organic coordination bonds are formed between Co2+ in CBMNs and the -COOH group in 6FDA-durene-DABA. As a result, the 6FDA-durene-DABA/CBMN MMMs exhibit improved separation performance for the CO2/CH4 and H2/CH4 gas pairs with H2/CH4 and CO2/CH4 selectivities up to 42.0 ± 4.0 and 33.6 ± 3.0, respectively. The enhanced interfacial interaction leads to the comprehensive separation performance of CO2/CH4 and H2/CH4 gas pairs approaching or surpassing the 2008 Robeson upper bound. In addition, the CO2 plasticization pressure of the MMMs is significantly enhanced up to ∼20 bar, which is 2 times that of the pure 6FDA-durene-DABA membrane. When separating a mixed gas of CO2/CH4, the selectivity of CO2/CH4 remains stable at around 23 and the CO2 permeability keeps around 400 barrer during the long-term test.

Interlayer coupling in two-dimensional (2D) layered materials plays an important role in controlling their properties. 2H- and 3R-MoS2 with different stacking orders and the resulting interlayer coupling have been recently discovered to have different band structures and a contrast behavior in valley physics. However, the role of carrier doping in interlayer coupling in 2D materials remains elusive. Here, based on the electric double layer interface, we demonstrated the experimental observation of carrier doping-enhanced interlayer coupling in 3R-MoS2. A remarkable tuning of interlayer Raman modes can be observed by changing the stacking sequence and carrier doping near their monolayer limit. The modulated interlayer vibration modes originated from the interlayer coupling show a doping-induced blue shift and are supposed to be associated with the interlayer coupling enhancement, which is further verified using our first-principles calculations. Such an electrical control of interlayer coupling of layered materials in an electrical gating geometry provides a new degree of freedom to modify the physical properties in 2D materials.

Cerium oxide (CeO2) nanoparticles (NPs) are massively used as abrasives in the chemical and mechanical polishing (CMP), an essential process to manufacture semiconductor wafers. The CMP process for arsenide-based semiconductor materials produces wastewater with co-occurring arsenic (As) ions and CeO2 NPs. We found that CeO2 NPs adsorbed both arsenite (As(III)) and arsenate (As(V)) ions and the adsorption isotherms suggested different adsorption energies and capacities of the two species. Applying the ferric reducing ability for nanoparticle assay, we revealed that the adsorbed As(III) and As(V) each reduced CeO2 NP surface reactivity but followed different mechanisms. The adsorbed As(III) ions below a critical coverage (110 mmol/kg) increased occupation of Ce 4f orbitals and thus reduced electron mobility of the original CeO2 NPs. The adsorbed As(V) ions withdrew electrons from Ce 4f orbitals and likely became oxidizing agents that greatly inhibited the original surface reducing ability. Electron paramagnetic resonance analysis further revealed that adsorbed As(III) and As(V) ions decreased the propensity of CeO2 NPs to produce reactive oxygen species. This work highlights the importance of examining NPs in their post-use phases in which surface reactivity and hazard potential can be greatly altered by chemical exposure history and NP surface transformations.

There is a critical need to use decentralized and/or point-of-use systems to address some challenging water quality issues in society. Sorption-based approaches are uniquely suitable for such applications because of their simplicity in operation; however, the sorbents must possess fast contaminant uptake kinetics to overcome short hydraulic contact times often encountered in small systems. Here we designed a two-sorbent system consisting of Fe

In nanocomposite electrodes, besides the synergistic effect that takes advantage of the merits of each component, phase interfaces between the components would contribute significantly to the overall electrochemical properties. However, the knowledge of such effects is far from being well developed up to now. The present work aims at a mechanistic understanding of the phase interface effect in C@TiO

Cell stimulation by electric signal is an important approach for the advancement of biomedicine. Triboelectric nanogenerators (TENG), capable of converting mechanical energies to electricity, provides an alternative strategy to stimulate cells in a desired fashion. In this work, a TENG driven electric stimulation system has been designed for biosafety evaluation and exploration of the fibroblast cell behaviors. A rotatory disc-shaped TENG (RD-TENG) was fabricated to obtain an adjustable range of alternating current outputs. The peak current generated in a range of 10–50 μA is suitable for promoting cellular proliferation behavior of L929 cells. At the optimum value of 50 μA, the promotion rate reached 53.8 ± 2.66% after two-day of intermittent stimulation. Also, the migration rate was increased by about 67% than that of the cells in the control group. In addition, under stimulation, the proliferation-related gene of L929 cells - proliferating cell nuclear antigen (Pcna) and the two migration-related genes - fibroblast growth factor 2 (Fgf2) and delta like non-canonical notch ligand 1 (Dlk1) were also found up-regulated, suggesting that TENG stimulation regulates cell proliferation and migration at the level of gene expression. The present study demonstrates the effectiveness of TENG and its safe operation conditions in biomedical stimulation, which paves a way for practical application of TENG on tissue formation, reepithelialization and tissue remodeling.

Metallic nanoparticles (NPs) can mediate electron transfer in water solutions. We report a chemical assay named “ferric reducing ability of nanoparticles” (FRAN), which is capable of probing electron fluxes at NP–water interfaces. The assay provides time-resolved colorimetric analysis for evaluating the surface reactivity of metallic NPs in redox processes and in elucidating the electron transfer schemes. FRAN includes the reduction of ferric (FeIII) to ferrous (FeII) ions by electrons transferred from NPs at the NP–water interface. In tests of 20 nm gold (Au) and silver (Ag) NPs, the plateaued FeII concentration after adequate reaction time was linearly correlated to the NP concentration. However, distinct kinetic trends, which are mathematically described by an exponential and logarithmic function, were observed between Ag and Au NPs. We developed two theoretical models, which correspond to two interfacial electron transfer schemes, to explain the difference between the materials. For Ag NPs, the occurring redox is a one-electron transfer from Ag0 to FeIII, leading to formation of Ag+ and FeII. Despite being a heterogeneous reaction including the NP solid and aqueous solution, it involves electron transfer at the interfacial region in which the collision between FeIII and Ag0 occurs in a approximately homogeneous manner, and thus its kinetics behaves as a pseudo first-order reaction. For Au NPs, an electron flux forms when electrons stored in the NP phase are “discharged” to reduce FelII at the interface, and the NPs act as electrodes. The experiments and models for FRAN can aid in the design of NP antioxidant functionality and assessment of environmental impacts of NPs in water or other fluids.

Interlayer coupling in two-dimensional (2D) layered materials plays an important role in controlling their properties. 2H- and 3R-MoS

Low-dimensional superconductor serves as an excellent platform for investigating emergent superconducting quantum oscillation phenomena. The low-dimensional natures of these materials, originating from the finite size which is comparable with the superconducting coherence length, indicate that the corresponding physical properties will be constrained by quantum confinement effects. Importantly, some of the frontiers and hot issues in low-dimensional superconductors, including the anomalous metal state during the superconductor-insulator transition, spin-triplet pairing mechanism in superconductors, thermal-excited and electrical current-excited vortex dynamics in superconductors, and the “charge-vortex duality” in quantum dot materials and superconducting nanowires, are strongly correlated with the superconducting quantum oscillation effects. In recent years, all the above-mentioned topics have achieved breakthroughs based on the studies of superconducting quantum oscillation effects in low-dimensional superconductors. Generally, the periodicity and amplitude of the oscillation can clearly demonstrate the relation between the geometric structure of superconductors and various superconducting mechanisms. In particular, superconducting quantum oscillation phenomena are always correlated with the quantization of magnetic fluxoids and their dynamics, the pairing mechanism of superconducting electrons, and the excitation and fluctuation of superconducting systems.In this review article, three types of typical superconducting quantum oscillation effects observed in low-dimensional superconductors will be discussed from the aspects of research methods, theoretical expectations, and experimental results. a) The Little-Parks effect is the superconducting version of the Aharonov-Bohm effect, whose phase, amplitude and period are all helpful in studying superconductivity: the phase reflects the pairing mechanism in superconductors, the amplitude can be used for investigating the anomalous metal state, and the period provides the information about the sample geometry. b) The vortex motion effect is excited by thermal fluctuation or electrical current, and the corresponding oscillation phenomena show distinct temperature-dependent amplitudes compared with the Little-Parks effect. c) The Weber blockade effect originates from the magnetic flux moving across the superconducting nanowire, and such an effect provides a unique nonmonotonic critical current \begin{document}$ {I}_{\mathrm{C}} $\end{document} under a magnetic field in \begin{document}$I\text{-}V$\end{document} characteristics. The prospects of the above-mentioned quantum oscillation effects of low-dimensional superconductors for applications are also discussed at the end of this review, including quantum computing, device physics and low-temperature physics.

The rapid advancement of implantable electronics makes exploring a novel power source urgent. Self-healable triboelectric nanogenerator (SH-TENG) is an emerging and promising candidate based on the combination of triboelectric effect, electrostatic induction and self-healing action. In this work, we present a novel near-infrared (NIR) irradiation induced SH-TENG as potential implantable power source. With well-defined three-layer structure, the PDMS acts as triboelectric layer, epoxy resin-based polysulfide elastomer as healing-assisting layer, and SH/CNTs as self-healable electrostatic induction electrode layer, respectively. Due to the remotely-induced dynamic disulfide exchange reaction stimulated by NIR irradiation, the quickly generated heat can be transferred from the bottom up, leading to a zipper-like self-healing process in SH-TENG. The electrical performance, Qsc (~16 nC), Voc (~50 V) and Isc (0.6 μA), respectively can be restored even after repairing for 5 times. Devices can be simply scaled up like LEGO blocks by contacting the side faces upon NIR irradiation, while scaling up the electric output performance as well. The healing process of SH-TENG has also been demonstrated through chicken skin, owing to the high penetrating ability of NIR in biological tissues which is beneficial to potential implantable electronics.

We have synthesized and characterized a new family of nematic all-aromatic polyesteramide thermosets based on 6-hydroxy-2-naphthoic acid (HNA), terephthalic acid (TA), and 4-acetamidophenol (AAP). In order to incorporate a high concentration of the amide-based monomer (AAP), the melt transition ( T K-N) and melt viscosity had to be lowered in order to maintain melt processable intermediates. Precursor thermoplastic reactive oligomers, end-capped with phenylethynyl functionalities, were prepared using standard melt condensation techniques with a target M n of 1000–9000 g mol−1. The reactive oligomers with 20–30 mol% AAP could easily be processed into films, and the films exhibit good tensile properties in terms of tensile strength (70–80 MPa) and elongation at break (7–10%). A glass transition of 191°C could be obtained when a 1000 g mol−1 oligomer (HNA/TA/AAP(20)–1 K) was thermally cross-linked. When the AAP concentration reaches 35 mol%, the rigidity of the backbone and the hydrogen bonding interactions are enhanced, which make HNA/TA/AAP(35) polymers difficult to process.

Highland crater Lalande (4.45°S, 8.63°W; D = 23.4 km) is located on the PKT area of the lunar near side, southeast of the Mare Insularum. It is a complex crater in Copernican era and has three distinguishing features: high silicic anomaly, the highest Th abundance and special landforms on its floor. There are some low-relief bulges on the left of Lalande's floor with regular circle or ellipse shapes. They are ∼250–680 m wide and ∼30–91 m high with maximum flank slopes >20°. There are two possible scenarios for the formation of these low-relief bulges which are impact melt products or young silicic volcanic eruptions. We estimated the absolute model ages of the ejecta deposits, several melt ponds and the hummocky floor and determined the ratio of diameter and depth of the crater Lalande. In addition, we found some similar bugle features within other Copernican-aged craters and there were no volcanic source vents on Lalande's floor. Thus, we hypothesized that these low-relief bulges were most consistent with an origin of impact melts during the crater formation instead of small and young volcanic activities occurring on the floor. Based on Kaguya Terrain Camera (TC) ortho-mosaic and Digital Terrain Model (DTM) data produced by TC imagery in stereo, geological units and some linear features on the floor and wall of Lalande have been mapped. Eight geological units are organized by crater floor units: hummocky floor, central peak and low-relief bulges; and crater wall units: terraced walls, channeled and veneered walls, interior walls, mass wasting areas, blocky areas, and melt ponds. These geological units and linear features provided us a chance to understand some details of the cratering process and elevation differences on the floor. We proposed that subsidence due to melt cooling, late-stage wall collapse and rocks uplifted from beneath the surface could be the possible causes of the observed elevation differences on Lalande's floor.

Engineered, natural or incidental colloidal-sized materials in tap water may originate from source water or be generated in distribution systems (e.g., corrosion-related). An optimized single-particle (sp)-ICP-MS technique was applied to tap water samples (n = 50) collected from three buildings to analyze for Pb, Fe, Sn, Cu, Ag and Ti-containing particles. The Pb, Sn and Fe-containing particles were detected at an average concentration (ng L−1) of 1.2 (range: 0.06–4.8), 1.8 (range: 0.11–14), and 88 (range: 26–890), respectively, representing the corresponding total dissolved metal concentrations at a minimum of 0.4%, 10%, and 15%. No particulate Ti and Ag were observed in the samples. The Pb concentrations in the first 125 mL fraction collected were on average three times higher than those in the subsequent samples. Detection of the Cu particles required modification of the sample introduction system (direct self-aspiration into the nebulizer) to reduce matrix interaction with the auto-sampler tubing. The Cu particles were detected in 50% of the analyzed samples at an average concentration of 69 (range: 15–136) ng L−1. While all the metal concentrations were below the health advisory levels, this study showcases the feasibility and first application of spICP-MS to monitor metal-containing particles in tap waters, and the results suggest that the particulate forms of the studied elements may represent a significant fraction of the bulk elemental concentration in tap water.

Metal organic frameworks (MOFs) are ideal fillers for preparing mixed matrix membranes (MMMs) because of their molecular sieving property. However, MOF nanoparticles are not easy to be dispersed, which limits their application in MMMs with high MOFs loading. In this study, highly dispersed ZIF-8 nanoparticles with diameter of around 50 nm were prepared by coating isophthalic dihydrazide (IPD) molecular layer onto their surfaces via coordination interaction (abbre. IPD@ZIF-8). Benefiting from the highly stable and highly dispersed IPD@ZIF-8 solution, MMMs with high nanoparticles loading content and excellent uniformity are achieved. The modification of IPD on the surface of ZIF-8 nanoparticles greatly enhances the interfacial affinity between ZIF-8 as filler and 6FDA-Durene polyimide (PI) as polymer matrix under the interaction of strong hydrogen bond between them. Gas permeation results reveal that the H2 permeability of IPD@ZIF-8 mixed PI (PI/IPD@ZIF-8) MMM with 45 wt% loading content is up to 8000 Barrer and the corresponding ideal selectivities of H2/CH4 and H2/N2 gas pairs are 15.1 and 13.0, which increase by 46.6% and 32.7%, respectively, comparing to those of ZIF-8 mixed PI (PI/ZIF-8) MMMs. The comprehensive separation performance of PI/IPD@ZIF-8 MMMs surpasses the 2008 Robeson’s upper bounds. The surface modification of IPD enhances the CO2 plasticization resistance property of PI/IPD@ZIF-8 MMMs from 21 bar to 30 bar. This study provides a facile and easy-operated strategy for the surface modification of MOF nanoparticles, and opens up a new way for the preparation of MMMs with high filler loading and good quality.

Numerous occurrences of hydrated minerals (e.g., phyllosilicate, sulfate) have been found on the surface of Mars by remote sensing and in-situ exploration missions, providing strong evidence of the aqueous environment in Martian history. However, the detailed origin of these hydrated minerals is often controversial, reducing their usefulness in constraining the aqueous history of Mars. For instance, in Ophir Chasma, the origins of hydrated sulfates are debatable among hypotheses of precipitating from groundwater, paleolake, or meteoric water. In this study, we performed detailed mineralogy, morphology and stratigraphy analyses of the hydrated phases in the mineral bowl, a depression between the southern wall and mensa of Ophir Chasma, using datasets from Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), High Resolution Imaging Science Experiment (HiRISE) and High Resolution Stereo Camera (HRSC). A large number of monohydrate sulfates (MHS), polyhydrated sulfates (PHS) and some jarosite were identified in this region. Elevation of PHS-rich regions (mean elevation of −1130 ​m) is higher than those of MHS (mean value of −1401 ​m). Spectra of poly- and monohydrated sulfates mixtures were investigated in details in laboratory. Spectral features (i.e., band depth of ~1.9 ​μm, 2.1 ​μm, convexity at 2.1 ​μm and 2.4 ​μm) of sulfates mixtures changed regularly with the abundance of endmember. The linear function between the ratio of BD2100_2 to SINDEX2 and kieserite component was set up to estimate hydrated sulfates abundance. We employ the function onto CRISM data and find a coexistence of poly- and monohydrated sulfates for the formerly recognized PHS endmember, which may indicate a local dehydration/rehydration process for the sulfated minerals. Comprehensive mineralogy, topography, and stratigraphy analyses of hydrated sulfates outcrops suggest a complex formation scenario which could include surface runoff, paleolake, even aeolian erosion.

In nanocomposite electrodes, besides the synergistic effect that takes advantage of the merits of each component, phase interfaces between the components would contribute significantly to the overall electrochemical properties. However, the knowledge of such effects is far from being well developed up to now. The present work aims at a mechanistic understanding of the phase interface effect in C@TiO2core-shell nanocomposite anode which is both scientifically and industrially important. Firstly, amorphous C, anatase TiO2and C@anatse-TiO2electrodes are compared. The C@anatase-TiO2shows an obvious higher specific capacity (316.5 mAh g-1at a current density of 37 mA g-1after 100 cycles) and Li-ion diffusion coefficient (4.0 × 10-14cm2s-1) than the amorphous C (178 mAh g-1and 2.9 × 10-15cm2s-1) and anatase TiO2(120 mAh g-1and 1.6 × 10-15cm2s-1) owing to the C/TiO2phase interface effect. Then, C@anatase/rutile-TiO2is obtained by a heat treatment of the C@anatase-TiO2. Due to an anatase-to-rutile phase transformation and diffusion of C along the anatase/rutile phase interface, additional abundant C/TiO2phase interfaces are created. This endows the C@anatase/rutile-TiO2with further boosted specific capacity (409.4 mAh g-1at 37 mA g-1after 100 cycles) and Li-ion diffusion coefficient (3.2 × 10-13cm2s-1), and excellent rate capability (368.6 mAh g-1at 444 mA g-1). These greatly enhanced electrochemical properties explicitly reveal phase interface engineering as a feasible way to boost the electrochemical performance of nanocomposite anodes for Li-ion batteries.

Molecular sieve materials (MSMs) are regarded as ideal fillers for the fabrication of mixed matrix membranes (MMMs). However, the preparation of MSMs-based MMMs usually involves physical mixing of insoluble filler and polymer matrix, which inevitably leads to filler agglomeration and two-phase incompatibility especially for high filler loading. Herein, we report a new strategy to construct MMMs through generating polymer molecular sieve (PMS) fillers in-situ in a thermally stable polymer matrix by post heating treatment. The in-situ generated PMS-based MMMs (i-PMS MMMs) possess greatly improved interfacial compatibility between matrix and filler and the effective loading content of PMS filler can reach as high as 70 wt%. The molecular sieving property of PMS endows the i-PMS MMMs with high gas selectivity of 183.0 for H2/CH4 and 128.9 for H2/N2, approaching or exceeding the state-of-the-art 2015 upper bound.

The electric-double-layer, constituted on the interface between an electronic conductor and an ionic conductor, enables practical applications of electronic devices and electrochemistry. Specifically, the electric-double-layer interfaces have been widely reported to achieve the insulator–metal transition and interfacial superconductivity in field-effect transistors because of the large electric-double-layer capacitance and high carrier density accumulation. Recently, a crystalline LaF3 solid electrolyte has been shown to be an ideal gate medium candidate for realizing stable electric-double-layer transistors. However, the intrinsic electrostatic and electrochemical mechanisms about LaF3 electric-double-layer interfaces remain elusive. Here, by combining electrochemical-impedance-spectroscopy with low-temperature technology, we demonstrate the temperature–frequency mapping “phase diagram” for the capacitance and dielectric loss at the LaF3/metal interfaces. Two well-distinguished regions correspond to the electrostatic and electrochemical nature, providing a promising guideline for practical device applications based on the crystalline LaF3 solid electrolyte.

Polyimide has been widely investigated as a potential material for gas separation. The post-crosslinking of polyimide could increase gas selectivity and membrane stability due to increase of chain-packing density and chain stiffness. However, common crosslinking strategies tend to destroy the chemical structure of polyimide. In this work, a strong hydrogen bond among polymer chains of 6FDA-durene polyimide (Du-PI) membranes is designed by introducing isophthalic dihydrazide (IPD) molecules as cross-linker. The formation of hydrogen bond between Du-PI and IPD strengthens the polymer interchain interaction and regulates interchain spacing but without breaking the chemical structure of Du-PI. The resulting IPD/Du-PI membranes exhibit largely enhanced mechanical strength and anti-plasticization property in comparison with pristine Du-PI membranes. In addition, due to the increased packing density of polymer chains, the membranes show obviously increased gas perm-selectivity by 296%, 505%, 125%, 66%, and 171% for H2/N2, H2/CH4, H2/CO2, O2/N2, and CO2/CH4 gas pair in the case of 20% IPD/Du-PI membrane. The use of IPD as cross-linker has demonstrated herein to be a facile and effective strategy to strengthen the inter-polymer chain interaction and simultaneously improve membrane stability in a mild way.

The semiconductor industry annually uses thousands of tons of nanoparticles (NPs) in chemical mechanical polishing (CMP) processes. When III/V materials are processed with CMP, the NPs and In(III), Ga(III) and As(V) ions (i.e., III/V ions) coincide and end up in wastewater from electronics fabrication lines. CMP NPs (colloidal SiO2 (C-SiO2), fumed SiO2 (F-SiO2), CeO2 and Al2O3) may interact with III/V ions (e.g. In(III), Ga(III) and As(V)) and facilitate their transport in aquatic systems. Across a range of pH levels, we found that appreciable adsorptions of In(III) ions onto CeO2 or Al2O3 NPs, Ga(III) ions onto C-SiO2, F-SiO2, CeO2 or Al2O3 NPs, and As(V) ions onto CeO2 or Al2O3 NPs occur. We determined the intrinsic surface complexation constant (KC,intr) between the ions and NPs by fitting the experimental data with a surface complexation model (SCM). We then extended the SCM to calculate adsorption as a function of NP size. As size increases, surface site density (SSD) increases, whereas specific surface area (SSA) decreases; both eventually reach a plateau where the bulk material stands. Nonetheless, mass site density (MSD), i.e. the site number per mass, increases with size reduction, indicating that smaller particles give higher adsorption capacity based on the same mass. Upon a 1 nm size reduction of C-SiO2 NPs, the model predicts that the MSD increases 100 nm and >10% for sizes

We designed the “catalytic reactivity to nanoparticle” assay (CRNP), which uses a dry powder containing methylene blue (MB) and sodium borohydride (NaBH4) to rapidly (2 min) detect metallic nanoparticles in water. Tested with gold (Au) NPs in water, the CRNP response was linearly and reproducibly correlated to the NP surface-area concentration and has a detection limit of 0.3 m2/m3 as the equivalent surface area of Au NPs. We described the heterogeneous catalytic mechanisms on the NP surface by treating the NPs as electrodes, which store and transfer electrons, and comprehensively simulated the kinetics of borohydride hydrolysis, MB reduction, and leuco methylene blue (LMB) oxidation. CRNP was able to assess the catalytic reactivity of multiple engineered NP species in water, including Au, silver, palladium, platinum, and copper oxide (CuO), and quantify them with pre-established calibration curves. In water samples containing known or unknown NP species, CRNP can be reported as an equivalent surface area...

As the first lunar farside landed mission, China’s Chang’E−4 (CE-4) has safely landed on the volcanically resurfaced floor of Von Karman crater in South Pole-Aitken (SPA) basin. The CE-4 mission will conduct rover exploration by Yutu-2 similar to what Chang’E−3 did in the northern Imbrium basin. Here we present a comprehensive study of the composition, mineralogy, and chronology of the basaltic and nonmare units in this crater, with the intent to provide context for the compositional properties of the landing site. Compositional maps (FeO, TiO2, Mg#, and Th) demonstrate the heterogeneous distribution of mare and nonmare materials. Using a spectral survey of 1899 small impact craters (

This tutorial review focuses on aqueous slurries of dispersed engineered nanoparticles (ENPs) used in chemical mechanical planarization (CMP) for polishing wafers during manufacturing of semiconductors. A research consortium was assembled to procure and conduct physical, chemical, and in vitro toxicity characterization of four ENPs used in CMP. Based on input from experts in semiconductor manufacturing, slurries containing fumed silica (f-SiO2), colloidal silica (c-SiO2), ceria (CeO2), and alumina (Al2O3) were selected and subsequently obtained from a commercial CMP vendor to represent realistic ENPs in simplified CMP fluids absent of proprietary stabilizers, oxidants, or other chemical additives that are known to be toxic. ENPs were stable in suspension for months, had highly positive or negative zeta potentials at their slurry working pH, and had mean diameters measured by dynamic light scattering (DLS) of 46 ± 1 nm for c-SiO2, 148 ± 5 nm for f-SiO2, 132 ± 1 nm for CeO2, and 129 ± 2 nm for Al2O3, all of which were larger than the sub 100 nm diameter primary particle sizes measured by electron microscopy. The concentration of ENPs in all four slurries that caused 50% inhibition (IC-50) was greater than 1 mg mL−1 based on in vitro assays using bioluminescence of the bacterium Aliivibrio fischeri and the proliferation, viability, and integrity of human cells (adenocarcinomic human alveolar basal epithelial cell line A549). The general practice in the CMP industry is to dilute the slurry waste stream so actual abrasive concentrations are typically orders of magnitude smaller than 1 mg mL−1, which is lower than IC-50 levels. In contrast to recent reports, we observed similar toxicological characteristics between c-SiO2 and f-SiO2, and the materials exhibited similar X-ray diffraction (XRD) spectra but different morphology observed using electron microscopy. The ENPs and CMP slurries used in this study have been made available to a number of other research groups, and it is the intention of the consortium for this paper to provide a basis for characterizing and understanding human and environmental exposures for this important class of industrial ENPs.

Single particle inductively coupled plasma mass spectrometry (spICP-MS) was used to detect Ti-containing particles in heavily-used bathing areas of a river (Salt River) and five swimming pools. Ti-containing particle concentrations in swimming pools ranged from 2.8 × 103 to 4.4 × 103 particles/mL and were an order of magnitude lower than those detected in the Salt River. Measurements from the Salt River showed an 80% increase in Ti-containing particle concentration over baseline concentration during peak recreational activity (at 16:00 h) in the river. Cloud point extraction followed by transmission electron microscopy with energy dispersive X-ray analysis confirmed presence of aggregated TiO2 particles in river samples, showing morphological similarity to particles present in an over-the-counter sunscreen product. The maximum particle mass concentration detected in a sample from the Salt River (659 ng/L) is only slightly lower than the predicted no effect concentration for TiO2 to aquatic organisms (

Metal-oxide resistive random access memories with a single memristor device at the crosspoint (1R RRAM) is a promising alternative to next generation storage technology due to their high density, scalability, non-volatility and low power consumption. However, the imperfect fabrication process introduces high defect rates of the nanoscale memristor devices and leads to yield degradation. In addition, sneak-paths occur in 1R RRAM crossbar that can jeaperdize the normal read/write operation. Previous work proposes voltage bias technique to eliminate the sneak-paths. Instead, in the paper, we leverage voltage bias to manipulate various distribution of sneak-paths that can screen one or multiple faults out of a 4 × 4 region of memristors at once, and consequently diagnose the exact location of each faulty memristor within three write-read operations. The SPICE simulation results highlight the effectiveness and efficiency of the proposed test method.

The quantification and characterization of natural, engineered, and incidental nano- to micro-size particles are beneficial to assessing a nanomaterial's performance in manufacturing, their fate and transport in the environment, and their potential risk to human health. Single particle inductively coupled plasma mass spectrometry (spICP-MS) can sensitively quantify the amount and size distribution of metallic nanoparticles suspended in aqueous matrices. To accurately obtain the nanoparticle size distribution, it is critical to have knowledge of the size detection limit (denoted as Dmin) using spICP-MS for a wide range of elements (other than a few available assessed ones) that have been or will be synthesized into engineered nanoparticles. Herein is described a method to estimate the size detection limit using spICP-MS and then apply it to nanoparticles composed of 40 different elements. The calculated Dmin values correspond well for a few of the elements with their detectable sizes that are available in the literature. Assuming each nanoparticle sample is composed of one element, Dmin values vary substantially among the 40 elements: Ta, U, Ir, Rh, Th, Ce, and Hf showed the lowest Dmin values, ≤10 nm; Bi, W, In, Pb, Pt, Ag, Au, Tl, Pd, Y, Ru, Cd, and Sb had Dmin in the range of 11-20 nm; Dmin values of Co, Sr, Sn, Zr, Ba, Te, Mo, Ni, V, Cu, Cr, Mg, Zn, Fe, Al, Li, and Ti were located at 21-80 nm; and Se, Ca, and Si showed high Dmin values, greater than 200 nm. A range of parameters that influence the Dmin, such as instrument sensitivity, nanoparticle density, and background noise, is demonstrated. It is observed that, when the background noise is low, the instrument sensitivity and nanoparticle density dominate the Dmin significantly. Approaches for reducing the Dmin, e.g., collision cell technology (CCT) and analyte isotope selection, are also discussed. To validate the Dmin estimation approach, size distributions for three engineered nanoparticle samples were obtained using spICP-MS. The use of this methodology confirms that the observed minimum detectable sizes are consistent with the calculated Dmin values. Overall, this work identifies the elements and nanoparticles to which current spICP-MS approaches can be applied, in order to enable quantification of very small nanoparticles at low concentrations in aqueous media.