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The magnetic properties, magnetocaloric effect and magnetoresistance in ErNi single crystal have been investigated in detail. With decreasing temperature, ErNi single crystal undergoes two successive magnetic transitions: a paramagnetic to ferromagnetic transition at TC =11 K and a spin-reorientation transition at TSR = 5 K. Meanwhile, a sharp field-induced metamagnetic transition is observed below the TC along the a axis. ErNi single crystal possesses a giant magnetocaloric effect around TC. The maximum magnetic entropy change is -36.1 J (kg K)−1 along the a axis under the field change of 0−50 kOe. In particular, the rotating magnetocaloric effect in ErNi single crystal reaches its maximum under a relatively low field, and the maximum rotating entropy change with a value of 9.3 J (kg K)−1 is obtained by rotating the applied field from the [011] to [100] directions under 13 kOe. These results suggest that ErNi could be a promising candidate for magnetic refrigeration working at liquid-helium temperature region. Moreover, a complicated transport behavior is uncovered in ErNi single crystal, which is attributed to the complex magnetic states and magnetic polaronic effect. Both positive and negative magnetoresistance are observed. A considerable large magnetoresistance with the value of -34.5 % is acquired at 8 K under 50 kOe when the field is along the [100] direction.

Solid-state refrigeration based on the magneto- or mechano-caloric effect, including elasto- and baro-caloric in ferroic phase transition materials is promising to replace the current vapor compression refrigeration in consideration of environmental-friendliness and energy-saving. However, both high driven field and small thermal changes in all of these caloric materials hinder the development of solid-state refrigeration. Here we report a giant baro-caloric effect near room temperature induced by a low hydrostatic pressure in Co-based Co51Fe1V33Ga15 Heusler alloy. The maximum adiabatic temperature change under the applied pressure change of Δp = 0.1–100 MPa can be as high as Δ T ad M a x = 7.7 K ( Δ T ad M a x / Δ p reaches up to ∼7.7 K kbar−1), surpassing the Δ T ad M a x / Δ p value reported hitherto in baro-caloric alloys. In addition, the microstructure is also studied by using the electron microscopes. Along with the austenite and martensite, the submicron V-rich particles are precipitated in this alloy, which are believed to account for enhancing mechanical properties.

Room-temperature catalytic decomposition of low-concentration volatile organic compounds (VOCs) in indoor air is an exciting dream to solve their pollution. Herein, two kinds of rare-earth elements (Y and La) were separately doped into birnessite-type MnO2 nanosheets in the form of single atoms by the hydrothermal method. As-synthesized La/MnO2 achieved 100% removal of 10 ppm toluene at 40 °C under the gas hourly space velocity of 60 L g-1 h-1, which was even somewhat better than the single Pt atom-doped MnO2. In addition, La/MnO2 showed the good durability at room temperature for 0.5 ppm toluene removal under the GHSV of 300 L g-1 h-1 and could be effectively regenerated at 105 °C. GC/FID, online-MS and TD-GC/MS analysis demonstrated that only ignorable trace benzene (∼3.4 ppb, < one thousandth of inlet toluene) was generated in the gas phase during catalytic decomposition of 10 ppm toluene at room temperature. This research sheds light on the development of low cost and high activity catalysts for low-concentration VOC oxidation at room temperature.

In the present work, we reveal a novel finding, that is, self-assembled grain boundary precipitates for realizing the magnetic-field-induced metamagnetic transition by employing low melting point metal in materials. This strategy has been experimentally verified in a well-established ferrimagnetic compound Mn2Sb by doping the bismuth (Bi) element with a low melting point of just 271.3°C. Bi solidifies later than the Mn2(Sb,Bi) main phase in (Mn2Sb)1-xBix system (the melting point of ~948°C for Mn2Sb), and aggregates spontaneously along the grain boundaries, forming Bi-rich grain boundary precipitates to coat main phase grains. This is very similar to the Nd-rich grain boundary phase in Nd-Fe-B permanent magnets. The fraction of Bi-rich grain boundary phase can be controlled by Bi-content. As a result, the magnetic field induced steep magnetoelastic transition from antiferromagnetic to ferrimagnetic is achieved in (Mn2Sb)0.89Bi0.11 alloy with giant multiple functional properties in Bi-doped Mn2Sb. Especially, the magnetic entropy change maximum nearly quadruples when Bi-doping increases from 0.03 to 0.11. Giant negative magnetoresistance of more than 65% under μ0∆H = 0–5 T, and magnetostrain of ~1802 ppm under μ0H = 8.5 T are obtained in (Mn2Sb)0.89Bi0.11. It should pave a way to achieve the magnetic transition and enhance the magnetoresponsive effects in designing similar coherent materials by employing low melting point metal doping to form the dual-phase heterogeneous structure.

The removal and recovery of volatile organic compounds (VOCs) are widely used in many industrials. Unfortunately, most conventional porous materials not only have low VOCs uptake, but also need to be regenerated at relatively high temperature. Metal-organic frameworks (MOFs) have great potential for the removal and recovery of VOCs as their record-breaking gas adsorption capacity, easy regeneration, tunable pore structure and functional groups. Whereas, powdered MOFs are hardly implemented in industrial fields owing to their low bulk density and high pressure drop. Exploring a green method to prepare granular MOFs for the removal and recovery of VOCs is still a challenge. Herein, we report the room temperature green synthesis of a stable Fe-based MOF monolith by using water as the solvent without applying high pressure and chemical binders. The static and dynamic experiments show that the optimized centimeter-scale monolith has high porosity and mechanical strength, and exhibits much better adsorption performance for representative aromatic VOCs (benzene, toluene and p-xylene), than commercial activated carbon and activated carbon fiber under the same conditions. Remarkably, as-synthesized monolith can be rapidly regenerated at lower temperature. These results clearly demonstrate the advantages of MOF monoliths in removing and recovering VOCs, and also provide new insight into the effects of drying temperature, washing and centrifugation procedures on MOF shaping.

We report the first statistical survey of the oxygen ion cyclotron harmonic waves observed by Van Allen Probes throughout the mission. An example event observed on 19 February 2014 after a strong magnetic storm and a substorm was first presented to demonstrate the general properties of OCH waves. The observed waves have multiple spectral peaks around harmonics of the oxygen ion gyrofrequency. During the event, oxygen ionsof 10s keV had a ring-like partial shell velocity distribution which might have driven the wave excitation through the oxygen ion Bernstein instability. On the other hand, the phase space densities of He+ and O+ less than a few hundred eV were larger around 90° pitch angle, indicating transverse heating of these ions. Our statistical study shows that the waves occurred over 2 < L < 6 and across all magnetic local time. More than 50% of the events were observed just outside the plasmapause, and the typical wave amplitude is between ~0.1 and several nT. The frequency spacing between two consecutive wave harmonics decreases with increasing L but stabilizes when L > 5. The frequency spacing is larger than the local oxygen ion gyrofrequency for many events, especially those observed at larger L, suggesting that these waves propagated there from lower L shell regions. The waves are mainly on the dayside at L > 4 under quiet geomagnetic conditions, but can occur at lower L shells with a more uniform MLT distribution under more active geomagnetic conditions.

The development of superhydrophobic adsorbents for the capture of trace volatile organic compounds (VOCs) from humid indoor air is still a challenge. Herein, we reported the formation of a granular zinc-based metal-organic gel, i.e., ZIF-412(gel) by optimizing the synthesis conditions. The thermally stable xerogel exhibited high surface area (1008 m

Porous carbon materials with chemical and thermal stability and high porosity have been widely used for volatile organic compound (VOC) purification. Designing granular carbon with remarkable adsorption capacity and rapid regeneration is of great significance for the capture of VOCs from high humidity air. Herein, a series of N-doped granular carbons were synthesized by direct carbonization of metal-organic gel (MOG). The N-doped granular carbons (C700 and C700K) feature high surface area, hierarchical pore, and abundant N,O multifunctional groups. The toluene adsorption capacity of C700K is highly improved (9.0 mmol/g toluene at P/P0 = 0.1) in comparison with MOG (4.81 mmol/g toluene at P/P0 = 0.1). The toluene breakthrough time of C700K is over 4 times longer than that of MOG at wet conditions (60% RH, 298 K), also much longer than that of widely used carbon materials, zeolites, and representative MOFs, including BPL activated carbon, coconut shell activated carbon, carbosieve, ZSM-5, and MIL-101(Cr). Furthermore, the N-doped granular carbons also exhibit excellent hydrophobicity and can be regenerated rapidly. The internal pore channel and desorption kinetics reveal that the effective diffusion length plays a critical role in the regeneration rate.

Room-temperature catalytic decomposition of low-concentration volatile organic compounds (VOCs) in indoor air is an exciting dream to solve their pollution. Herein, two kinds of rare-earth elements (Y and La) were separately doped into birnessite-type MnO

Carbon frameworks (CFs) derived from metal-organic frameworks (MOFs) have been produced as adsorbents of toluene. To further obtain optimum hierarchical porous carbon structure of CFs, different treatment temperatures were applied to a typical kind of MOFs (ZIF-8). The adsorption capacity of the toluene of hierarchical porous CFs obtained from ZIF-8 under 1100 °C (CF-1100, adsorption capacity of 208.5 mg/g) was higher than that of other carbonization temperature and MOFs. Impressively, the adsorbent CF-1100 also exhibited strong hydrophobicity, low desorption temperature, and good selectivity to toluene. The adsorption capacity decreased by only 10.4% under wet condition compared with the dry condition, standing on the top of the recently reported adsorbents. The impressive adsorption performance of CF-1100 is attributed to the larger specific surface area (1024 m2/g) and pore volume (0.497 cm3/g), newly generated micropores (pore width is 0.6–0.8 nm) and mesopores (pore width above 10 nm), and carbonaceous structure with higher degree of graphitization. Based on the adequate adsorption performance, CF-1100 coated quartz crystal microbalances as sensor also showed a high sensitivity of 0.4004 Hz/ppm and small relative standard deviations of 1.0745% for toluene sensing. This contribution provides a foundation for optimizing potential adsorbents and sensing materials for air pollution abatement.

Exploring a synthesis method for preparing hydrophobic metal-organic gels (MOGs) is highly desirable for air purification. Here, we present a rapid heating-up synthetic route to hydrophobic MOG denoted CAU-3(gel) with hierarchical micro/mesoporosity. CAU-3(gel), which features water and thermal stability, high surface area, and hydrophobicity, exhibits excellent performance for the capture of three representative volatile organic compounds (hexanal, toluene, and p-xylene), higher than BPL activated carbon, zeolite 13X, and some representative metal-organic frameworks including ZIF-8, HKUST-1, MIL-101(Cr), and UiO-66 under wet conditions. Furthermore, CAU-3(gel) could be easily coated on a nonwoven fabric by a simple dip-coating method without using any binder, which exhibits outstanding hexanal removal performance and regenerability at low temperature. Grand canonical Monte Carlo simulations show that hexanal preferentially enters relatively small tetrahedral cages and occupies two adsorption sites at low pressure and then a new site appears in octahedral cages with increasing pressure.

Loading catalyst nanoparticles onto polymer fibers for the removal of indoor pollutants such as HCHO encounters many problems such as uneven distribution, active site coverage, high cost and environmental pollution. Here we efficiently loaded MnO2 on the surface of polyethylene terephthalate (PET) fibers (MnO2@PET) within 10 s by utilizing the friction heat and mechanical action generated between MnO2 and PET fibers during rapid stirring. The thickness of the MnO2 coating ranged from ∼0.14 µm to 2.19 µm. After initial weight loss of 10.2 ∼ 10.4% in the first 30 min, the composite fibers remained stable weight in the later 150 min during ultrasonic oscillation, indicating the durability and fastness of the MnO2 coating. As-synthesized MnO2@PET composites enabled superior HCHO removal rate (95.5%) and conversion to CO2 (75.5%) within 120 min at room temperature, and it can be easily regenerated at low temperature (60 °C).

We report anisotropic magnetocaloric effect and magnetoresistance in antiferromagnetic HoNiGe3 single crystal grown by Ge flux method. HoNiGe3 single crystal exhibits antiferromagnetic order and large magnetocrystalline anisotropy below the Neel temperature TN = 10.5 K. Meanwhile, with increasing the magnetic field, HoNiGe3 undergoes the spin-flip transition induced by the magnetic field along the a axis, while the spin-flop transition occurs for the field along the other orientations, which gives rise to anisotropic magnetoresistance behavior along three axes. With the magnetic field change of 0–50 kOe, the maximum magnetic entropy changes obtained along the a, b, and c axes are −13.9, 2.5 and −7.7 J kg−1K−1, respectively. The maximum rotating magnetic entropy change is −12.3 J kg−1K−1 under 50 kOe by rotating the magnetic field from the b axis to the a axis, and the corresponding refrigeration capacity is 193 J/kg, which demonstrates HoNiGe3 to be an attractive candidate for novel rotating magnetic refrigeration at low temperature region.

The topological Hall effect (THE) in general arises from the Berry phase acquired by conduction electrons moving in a noncoplanar spin textures such as skyrmions. In this paper, low-field induced THE is realized in a chiral-lattice B20-ordered Cr0.82Mn0.18Ge alloy. The maximum topological Hall resistivity of ρ xy T ≈ −0.048 μΩ cm at T = 10 K is achieved under a low magnetic field of about μ0H = 0.04 T, which reaches up to ~20% of the anomalous Hall effect. Dip/peak anomalies are observed in the field dependence of AC-susceptibility, which indicates the field evolution of the topologically protected nontrivial spin textures. The results manifest that the Cr0.82Mn0.18Ge alloy should host skyrmions and pave the way for searching new skyrmions materials.

The effects of Cu substitution and annealing on the martensitic transformation behavior and magnetocaloric properties in all- d -metal Mn50Ni32– x Cu x Co8Ti10 ( x =1, 2) alloy ribbons have been mainly investigated. After the substitution, it is observed that the martensitic transformation temperature of the alloys, which was extremely sensitive to the Cu content, was reduced. Moreover, the ferromagnetism of austenite increased, increasing the magnetization difference across the martensitic transformation. The magnetic-field-induced metamagnetic martensitic transformation also occurred. The magnetic entropy change gradually increased, and the effective refrigeration capacity increased by more than twice than that of the Cu-free substitution. Moreover, the sample with x =1 was utilized as the research object to study the effect of annealing on the martensitic transformation. After annealing, the martensitic transformation became slow and the austenite ferromagnetism decreased. The change in the magnetization across the phase transition was also reduced. The magnetic-field-induced metamagnetic martensitic transformation was also weakened. Consequently, the magnetic entropy change was greatly reduced. However, the effective refrigeration capacity did not reduce significantly because the refrigeration temperature interval increased largely. In this paper, the physical mechanisms of the effects of Cu substitution and annealing on the martensitic transformation were discussed from the change in the d - d interaction and the precipitation in the γ -phase, respectively.

Heavy metals are seriously hazardous contaminants and drinking water has been identified as an important route of human exposure to them. Herein, to efficiently and selectively remove trace heavy metal ions, a facile method was reported to achieve the slow polymerization of dopamine in the cages of MIL-100 (Fe) via ultrasonic treatment followed by the hydrolysis of the urea. X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), Brunner-Emmet-Teller (BET) and pore size distribution determination confirmed the formation of the polydopamine (PDA) and binding with the unsaturated Fe3+ site in MIL-100 (Fe) pores. The composite not only retained pore structure of MOFs but also contained abundant reactive functional groups. When initial lead concentration was 150 ppb and 20 ppm calcium coexisted at pH of 6.5 ± 0.25, the effluent lead concentration met the safe drinking water standard in several tens of seconds, and decreased to 1.13 ppb in 10 min. The adsorption rate reached 99.35%. The synthetic strategy effectively overcomes mass transfer resistance of trace heavy metal ions and provides a facile approach to prepare adsorption materials for efficient and selective removal of trace heavy metal ions from drinking water.

We report the observation of the giant topological Hall effect near room temperature in a complex noncollinear ferromagnet NdMn2Ge2 single crystal. Three successive magnetic transitions are observed below 400 K, including a spin reorientation transition at TSR = 215 K. The complex noncollinear magnetic structures give rise to anomalous transport behaviors. When the current flows along the a axis and the magnetic field is applied along the c axis, the anomalous Hall effect is observed, which is found to be dominated by the skew scattering mechanism. Strikingly, a giant topological Hall effect appears in a wide temperature range, which stems from the noncollinear spin configuration with finite scalar spin chirality. The topological Hall resistivity reaches the maximum of −1.35 μΩ cm at 300 K and drops slightly with temperature until below TSR. These results suggest that the NdMn2Ge2 single crystal would be a promising topological material for spintronic applications at room temperature.

Carbonation of Ca/Mg minerals in industrial alkaline residues is a technology to sequester CO2 and reduce its emissions to the atmosphere. In this work, BSE-EDS were used to determine the mineral phase in steel slag; compositions of RO phase were identified and simulated. The carbon sequestration of steel slag was studied, and RO phase was activated by carbonation. Result shows that the amount of CO2 sequestered in steel slag and RO phase increases as carbonation time increases. Under autoclaving condition, the hydration ratio of MgO in RO phase was 20.10%. Through carbonation, up to 58.83% of MgO in RO phase can be converted into MgCO3, and the activation of RO phase by carbonation was manifested. The mechanical properties and volume stability of carbonated steel slag were improved, proving that the positive effect of carbonation on steel slag when applied in cement and cementitious materials.

We report on giant rotating magnetocaloric effect in antiferromagnetic ErNi3Al9 single crystal with the trigonal structure. It is found that the signs of the magnetic entropy change for the field along the c axis and ab plane above the Neel temperature are opposite due to the crystal electric field. Therefore, the giant rotating magnetocaloric effect is obtained in ErNi3Al9 single crystal, and even larger than the conventional one. The maximum rotating magnetic entropy change and refrigerant capacity are 14.7 J/kg K and 180.3 J/kg under 50 kOe. In particularly, the value of rotating adiabatic temperature change reaches 9 K under 50 kOe at 10 K. Our results indicate that ErNi3Al9 single crystal could be an attractive candidate for novel rotating magnetic refrigeration at low temperature region. Most importantly, it is further revealed that giant rotating magnetocaloric effect in ErNi3Al9 single crystal should be attributed to the crystal electric field anisotropy, which may pave a new way to search for novel materials possessing giant rotating magnetocaloric effect.

The magnetic glass state has been proposed and studied in the ferromagnetic (FM) compounds undergoing the first-order FM-antiferromagnetic (AFM) transition. In this work, we have unequivocally demonstrated the occurrence of magnetic-glass-like transition during the field cooling process in the ferrimagnetic (FIM) Mn1.975Cr0.025Sb alloy showing a first-order FIM-AFM transition. The magnetic, resistance and relaxation studies characterize the formation of a nonergodic magnetic glass-like state at low temperature arising from the coexistence of AFM and kinetically arrested FIM phases above a critical applied field. The magnetic field-temperature (μ0H-T) phase diagram based on magnetic and resistance measurements further evidences the generality of onset of glassy behavior in the first-order magnetic transition materials, in which the transition temperature shifts strongly with increasing applied field.

Trace volatile organic compounds (VOCs) such as aldehydes and aromatics significantly deteriorate the indoor air quality especially in newly-decorated buildings. The universal water vapor would greatly decrease the adsorption capacity of adsorbents for trace VOCs via competitive adsorption and capillary condensation. Herein, we developed a strategy to subsequently modify the internal and external surface of CAU-1, an aluminum-based metal-organic framework (MOF), to significantly improve its humidity resistance. First, anhydrides were used to transfer amino groups of CAU-1 into hydrophobic groups via amide reaction. Second, polydimethylsiloxane was used to form a hydorphobic coating on its external surface. The adsorption capacity of as-modified CAU-1 for 1 ppm toluene increased about 6 times under 50% relative humidity (RH) at 298 K, even much higher than those of common adsorbents including hydrophobic ZSM-5. In addition, it could be completely regenerated below 373 K, about 65 K lower than that required for regenerating ZSM-5 under the same condition, which not only greatly reduces the energy consumption but also improves the safety and feasibility of in-situ regeneration of adsorbents in indoor environment.

Cloud occurrences, vertical structures, and along-track horizontal scales over East Asia are studied using four years (2007–2010) of CloudSat 2B-CLDCLASS-LIDAR data. The CloudSat 2B-CLDCLASS-LIDAR data employs combined CloudSat radar and Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) measurements to provide by far the most accurate detections of cloud boundaries and their vertical structures. The mean cloud occurrence frequency over East Asia is 66.3%, which is 13.8% and 21.6% higher than that from the Cloud–Aerosol LIdar with Orthogonal Polarization (CALIOP) level 2 5-km cloud layer product and the CloudSat 2B-GEOPROF product, respectively. Cloud-top heights over East Asia show three local peaks at approximately 1.5 km, 10 km, and 15 km above ground level (AGL), indicating different mid-altitude cloud formation mechanisms from those over the tropics. Significant fractions of low-level cloud, mid-level cloud, and high-level cloud have thicknesses smaller than 0.5 km, indicating that models with vertical resolutions lower than 0.5 km have difficulties resolving those clouds. The average cloud along-track horizontal scale over East Asia is 82.0 km. Probability distribution functions (PDFs) of cloud along-track horizontal scales suggest that approximately 81.2% of the clouds over East Asia cannot be resolved by climate models with a grid resolution of 1°. The results from this study can be used to improve cloud parameterizations in climate models and validate model simulations of clouds over East Asia.

The increasing nuclear energy consumption has posed serious environmental concerns (e.g. nuclear leakage), and the removal of radionuclides such as cesium becomes an urgent issue to be solved currently. In this research, a novel non-toxic adsorbent lithium-modified montmorillonite clay encapsulated in calcium alginate microbeads (MCA/Li) was fabricated by using ion-exchange method and then used successfully in the remediation of cesium-contaminated wastewater. Analyses of scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy were used to characterize the physicochemical properties of adsorbent MCA/Li, such as internal crystal structure, constituent elements, and functional groups. The effects of concentration ratios (sodium alginate/montmorillonite), solution pH, contacting time and initial Cs

Nowadays atmospheric ozone pollution increasingly occurs in summer in China developed areas. To improve catalytic stability of MnO2 for decomposing ozone in real humid environment, we developed a simple method to obtain the ammonium (NH4+) treated birnessite-type MnO2 (N-MnO2). NH4+ ions not only replaced K+ ions in the interlayer of MnO2 but also existed on the surface of MnO2, separating the original aggregated MnO2 nanoparticles into smaller ones. The N-MnO2 had much larger specific surface area than the original MnO2 (221 m2/g vs. 59 m2/g), leading to more oxygen vacancies and enhanced surface acidity. As a result, N-MnO2 exhibited excellent and stable activity for ozone decomposition in humid condition (relative humidity 50%) at room temperature, achieving 80% conversion of 115 ppm ozone under the space velocity as high as 600 L/gcat·h. In addition, N-MnO2 powder was successfully coated on the non-woven fabric. This composite material not only showed stable 60–80% conversion of 15 ppm ozone in a 7-day test, but also its air pressure-drop was only 3 Pa under the commonly used air filtration face velocity of 5.3 cm/s. Thus, as-synthesized N-MnO2 showed great potential in real building ventilation system to prevent ozone pollution from outdoor air.

The catalytic degradation of volatile organic compounds (VOCs) at low temperature is still a great challenge for indoor air purification. In this paper, the doping of single-atom Pt into MnO2 with a one-pot hydrothermal process greatly improved the catalytic activity for toluene degradation at room temperature, achieving 100% conversion of 0.42 ppm toluene at 28 °C under the high gas-hourly-space-velocity of 300 L g−1 h−1. Furthermore, it achieved 100% conversion of 10 ppm toluene at 80 °C and complete oxidation into CO2 at 220 °C. The manganese and oxygen defects in MnO2 nanosheets effectively stabilized the single-atom platinum, and strong oxidative hydroxyl radicals ( OH) is thought to contribute to its excellent performance.

To remove cesium ions from water and soil, a novel adsorbent was synthesized by following a one-step co-precipitation method and using non-toxic raw materials. By combining ammonium-pillared montmorillonite (MMT) and magnetic nanoparticles (Fe

This paper proposed the role and composition of an e-business ecosystem, and analyzed some problems likely to occur among members of an e-business ecosystem such as trust, interest scrambling, information asymmetry, and coordination. Finally, it proposed four coordinating mechanisms-relation coordinating, interest coordinating, information coordinating, and operation coordinating.