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Records from natural archives show that the strength of the East Asian summer monsoon (EASM) strongly depends on the orbital configuration of the Earth. However, the dominant orbital cycles driving EASM have been found to be spatially different. Speleothem stable oxygen isotopic records from southern China, which are believed to reflect large-scale changes in the Asian monsoon system, are dominated by climatic precession cycles. Further north, on the Chinese Loess Plateau (CLP), loess-and-paleosol sequences, which are argued to be controlled by monsoon intensity, are in pace with global ice volume changes dominated by obliquity, and after the mid-Pleistocene transition by 100-kyr cycles. To understand these critical discrepancies, here we apply a novel proxy based on the trace metal compositions of pedogenic carbonate in the eolian deposits on the CLP to reconstruct summer precipitation over the last 1.5 million years. Our reconstructions show that summer precipitation on the CLP is dominantly forced by obliquity not in pace with the ice-volume-imprinted loess-paleosol sequences before and after the mid-Pleistocene transition or with the precession-paced speleothem oxygen isotopic records. Coupled with climate model results, we suggest that the obliquity-driven variations of summer precipitation may originate from the gradient of boreal insolation that modulates the thermal contrast between the Asian continent and surrounding oceans.

Combined thermo-chemotherapy displays outstanding synergically therapeutic efficiency when compared with standalone thermotherapy and chemotherapy. Herein, we developed a smart tri-stimuli-responsive drug delivery system involving X@BB-ZrO2 NPs (X represents loaded IL, DOX, keratin and tetradecanol) based on novel ball-in-ball-structured ZrO2 nanoparticles (BB-ZrO2 NPs). The microwave energy conversion efficiency of BB-ZrO2 NPs was 41.2% higher than that of traditional single-layer NPs due to the cooperative action of self-reflection and spatial confinement effect of the special two-layer hollow nanostructure. The tri-stimuli-responsive controlled release strategy indicate that integrated pH, redox and microwaves in single NPs based on keratin and tetradecanol could effectively enhance the specific controlled release of DOX. The release of DOX was only 8.1% in PBS with pH = 7.2 and GSH = 20 μM. However, the release could reach about 50% at the tumor site (pH = 5.5, GSH = 13 mM) under microwave ablation. The as-made X@BB-ZrO2 NPs exhibited perfect synergic therapy effect of chemotherapy and microwave ablation both in subcutaneous tumors (H22 tumor-bearing mice) and deep tumors (liver transplantation VX2 tumor-bearing rabbit model). There was no recurrence and death in the X@BB-ZrO2 + MW group during the therapy of subcutaneous tumors even on the 42nd day. The growth rates in the deep tumor of the control, MW and X@BB-ZrO2 + MW groups were 290.1%, 14.1% and -42% 6 days after ablation, respectively. Dual-source CT was used to monitor the metabolism behavior of the as-made BB-ZrO2 NPs and traditional CT was utilized to monitor the tumor growth in rabbits. Frozen section examination and ICP results indicated the precise control of drug delivery and enhanced cytotoxicity by the tri-stimuli-responsive controlled release strategy. The ball-in-ball ZrO2 NPs with high microwave energy conversion efficiency were first developed for synergic microwave ablation and tri-stimuli-responsive chemotherapy, which may have potential applications in clinic.

The antiperovskite Mn 3 Ga 1−x Ge x N (x=0, 0.1, 0.2, 0.3, 0.4 and 0.5) compounds were prepared by a method of solid-state sintering at 860 °C under a nitrogen atmosphere for 24 h. The Mn 3 Ga 1−x Ge x N compounds were characterized by X-ray diffraction, thermal dilatometer and physical property measurement system (PPMS), respectively. The experimental results indicate that the starting temperature of negative thermal expansion (NTE) is obviously moved toward a higher temperature region with the increase of Ge content. Meanwhile, the absolute value of coefficient of NTE (|α|) decreases continuously. Accordingly, the near zero thermal expansion (ZTE) behavior is explored at an approximate temperature range of 423–475 K for Mn 3 Ga 0.5 Ge 0.5 N. Furthermore, the mechanism of ZTE is also discussed. The present ZTE behavior serves as a valuable example for demonstrating the promise of exploring other potential ZTE materials in the family of antiperovskite manganese nitrides.

The cytotoxic reactive oxygen species (ROS) generated by photoactivated sensitizers have been well explored in tumor therapy for nearly half a century, which is known as photodynamic therapy (PDT). The poor light penetration depth severely hinders PDT as a primary or adjuvant therapy for clinical indication. Whereas microwaves (MWs) are advantageous for deep penetration depth, the MW energy is considerably lower than that required for the activation of any species to induce ROS generation. Herein we find that liquid metal (LM) supernanoparticles activated by MW irradiation can generate ROS, such as ·OH and ·O2. On this basis, we design dual-functional supernanoparticles by loading LMs and an MW heating sensitizer ionic liquid (IL) into mesoporous ZrO2 nanoparticles, which can be activated by MW as the sole energy source for dynamic and thermal therapy concomitantly. The microwave sensitizer opens the door to an entirely novel dynamic treatment for tumors.

Thermally conductive but electrically insulating materials are highly desirable for thermal management applications in electrical encapsulation and future energy fields, for instance, superconducting magnet insulation in nuclear fusion systems. However, the traditional approaches usually suffer from inefficient and anisotropic enhancement of thermal conductivity or deterioration of electrical insulating property. In this study, using boron nitride sphere (BNS) agglomerated by boron nitride (BN) sheets as fillers, we fabricate a series of epoxy/BNS composites by a new approach, namely gravity-mix, and realize the controllable BNS loading fractions in the wide range of 5&ndash, 40 wt%. The composites exhibited thermal conductivity of about 765% and enhancement at BNS loading of 40 wt%. The thermal conductivity up to 0.84 W&middot, m&minus, 1&middot, K&minus, 1 at 77 K and 1.66 W&middot, 1 at 298 K was observed in preservation of a higher dielectric constant and a lower dielectric loss, as expected, because boron nitride is a naturally dielectric material. It is worth noting that the thermal property was almost isotropous on account of the spherical structure of BNS in epoxy. Meanwhile, the reduction of the coefficient of thermal expansion (CTE) was largely reduced, by up to 42.5% at a temperature range of 77&ndash, 298 K.

With extensive investigations involving liquid metals (LMs), Ga-based LMs have attracted increasing attention from biomedical researchers because of their good biocompatibility, ideal fluidity, and high thermal conductivity. LMs employed in cancer treatment suffer from high surface tension, thereby yielding unstable nanoparticles (NPs). Here, ZrO2 is coated onto LM NPs to form a stable core-shell nanostructure. In particular, LM NPs coated with ZrO2 and modified by PEG (LM@pZrO2 NPs) still maintain favorable flexibility, which is beneficial for cellular uptake. With regard to the photothermal properties of LM, LM@pZrO2 NPs rapidly warm up and emit the requisite amount of heat under NIR laser radiation. It is confirmed that LM@pZrO2 NPs are more effectively internalized by cells and are beneficial for tumor photothermal therapy. This research provides a coating strategy to fabricate a stable and flexible core-shell LM nanostructure, making it a promising vehicle for nanotheranostics.

Fracture of brittle filaments plays a crucial role in significant degradation of critical current density of multifilamentary Nb3Sn strand. Recent researches of distribution of filament factures mostly depend on photographic analysis with SEM or TEM. However, it is hard to obtain spatial distribution of filament fractures in the mulitifilamentary Nb3Sn strand. In addition, almost unavoidable filament fracture is introduced during the sample preparation procedure and it causes deviation of filament fracture distribution. X-ray microtomography is a non-invasive, non-destructive method, which allows determination and the discrimination of internal features without destructing the sample. It is widely used as a non-destructive test technology for its high penetrability and high resolution. This present work investigated filament fracture of two types of Nb3Sn strands under different tensile strains by high energy X-ray. The influence of tensile strain on the filament fracture behavior was investigated and the results will be expected to provide reference for optimization of multifilamentary Nb3Sn strand, conductor and magnet design.

Superconducting magnet is a key component in magnetic resonance imaging (MRI). In general, vacuum pressure impregnation (VPI) technology is used for insulating system of the superconducting magnet. Performance of the superconducting magnets is affected by the adhesion strength between superconducting wires and resins at cryogenic temperature. In this study, experimental superconducting coil was prepared by modified bisphenol-A type epoxy resin and the VPI technology. Tensile, shear, and compressive properties of the samples cut from the superconducting coil were measured at both room temperature (RT) and liquid nitrogen temperature (77 K), and the bonding properties between the superconducting wire and the resin were discussed. The results show that the resin exhibits low viscosity, long pot life and higher mechanical strength, and it is suitable for impregnating superconducting magnets by VPI technology. Moreover, the shear and compressive strength of the impregnated superconducting magnet at 77 K are significantly higher than that at room temperature, with the increase of 132% in radial compressive strength, 170% in axial compressive strength, 63% in radial shear strength and 70% in axial shear strength, respectively. This study provides references for the design of insulation for superconducting magnet system and the manufacture of insulating materials for MRI superconducting magnets.

With the development of electronic devices, high thermal conductivity polymer will become an ideal electronic packaging material. Therefore, Polyvinylidene fluoride (PVDF) nanocomposite was prepared doped with boron nitride nanosheet (BNNS), which has significantly improved thermal conductivity, excellent electrical insulation and outstanding flexibility. These nanocomposite films were prepared by mixing BNNS/PVDF in organic solution, drying, slicing, and then hot-pressing. Compared with the pristine polymers, the nanocomposite films have excellent thermal conduction, which indicates that new high-performance thermal conductivity materials will play an important role in high-power density electronic devices.

Shape memory alloy (SMA) sheets processed via unidirectional rolling (UniR) exhibit macroscopic low thermal expansion (TE) over a wide temperature span but only along a certain direction. Here, we use controlled cross rolling (CroR) to achieve in-plane low coefficients of TE (CTEs) of polycrystalline NiTi sheets. It is shown that the in-plane CTEs of a CroRed NiTi sheet with the three-step rolling path (RD-15%, TD-10% and RD-5%) can be reduced close to zero within a very narrow range (-2.7 × 10−6 K−1 to +3.0 × 10−6 K−1) over a large temperature span of 223 K. The obtained in-plane CTEs are an order of magnitude smaller than those of UniRed NiTi sheets and are comparable to that of commercial FeNi Invar alloy (+2.0 × 10−6 K−1). The physical origin of such in-plane low TE is explored through in situ neutron diffraction from 2.3 K to 300 K and a rule-of-mixture theoretical model. It is found that in the CroRed nanostructured NiTi, the in-plane positive TEs of textured B2 and B19’ aggregates are compensated by the in-plane negative TE caused by the continuous formation (vanishing) of { 102 } 〈 U V W 〉 fiber-textured B19’ variants in cooling (heating), thereby leading to the overall in-plane low TE. Such compensation mechanism in CroR can also be used to achieve in-plane low TE of other SMAs.

Herein, a rapid, straightforward, reliable, and low-cost strategy for targeted capture and detection of bacteria using carbohydrate-conjugated mesoporous silica structure was developed. Fingerprint-like mesoporous silica net (FMSN) with well-defined three-dimensional architecture and ordered morphology was first facilely synthesized by the aid of tetrabutylammonium iodine (TBAI) as cotemplates with cetyltrimethylammonium bromide (CTAB). When conjugated with maltoheptaose as targeting moiety, FMSN showed efficient and selective capturing capability of Staphylococcus epidermidis. This new and unique platform for capturing S. epidermidis is fast (within 18 min), high efficiency (greater than 98.6% from 1 × 103 CFU/mL to 1 × 108 CFU/mL), specific (compared to M. smegmatis mc2 155), and reusable (6 cycles).

The controllable isotropic thermal expansion with a broad coefficient of thermal expansion (CTE) window is intriguing but remains challenge. Herein we report a cubic MZrF6 series (M = Ca, Mn, Fe, Co, Ni and Zn), which exhibit controllable thermal expansion over a wide temperature range and with a broader CTE window (−6.69 to +18.23 × 10–6/K). In particular, an isotropic zero thermal expansion (ZTE) is achieved in ZnZrF6, which is one of the rarely documented high-temperature isotropic ZTE compounds. By utilizing temperature-dependent high-energy synchrotron X-ray total scattering diffraction, it is found that the flexibility of metal···F atomic linkages in MZrF6 plays a critical role in distinct thermal expansions. The flexible metal···F atomic linkages induce negative thermal expansion (NTE) for CaZrF6, whereas the stiff ones bring positive thermal expansion (PTE) for NiZrF6. Thermal expansion could be transformed from striking negative, to zero, and finally to considerable positive though tuning the fle...

A fast and furnace-free method of combustion synthesis is employed for the first time to synthesize iron-based superconductors. Using this method, Fe1.1Se1-xTex (0, 20 pages, 6 figures

Intrinsic isotropic near-zero thermal expansion is discovered in borate crystal Zn4 B6 O13 with high transparency in the ultraviolet region. First-principles calculations demonstrate that the very low thermal expansion originates mainly from the invariability of the solid [B24 O48 ] truncated octahedra that are fixed by the [Zn4 O13 ] clusters in the ZBO structure.

Dense bulk samples of (Ag,In)-co-doped Cu2SnSe3 have been prepared by a fast and one-step method of combustion synthesis, and their thermoelectric properties have been investigated from 323 to 823 K. The experimental results show that Ag-doping at Cu site remarkably enhances the Seebeck coefficient, reduces both electrical and thermal conductivities, and finally increases the figure of merit (ZT) value. The ZT of the Cu1.85Ag0.15SnSe3 sample reaches 0.80 at 773 K, which is improved by about 70% compared with the unadulterated sample (ZT = 0.46 at 773 K). First principle calculation indicates that Ag-doping changes the electronic structure of Cu2SnSe3 and results in larger effective mass of carriers, thus enhancing the Seebeck coefficient and reducing the electrical conductivity. The low electrical conductivity caused by Ag-doping can be repaired by accompanying In-doping at Sn site, and by (Ag,In)-co-doping the thermoelectric properties are further promoted. The (Ag,In)-co-doped sample of Cu1.85Ag0.15Sn0.9In0.1Se3 shows the maximum ZT of 1.42 at 823 K, which is likely the best result for Cu2SnSe3-based materials up to now. This work indicates that co-doping may provide an effective solution to optimize the conflicting material properties for increasing ZT.

Thermoelectric materials are attractive for solar thermal energy conversion and waste heat recovery. The existing methods for fabricating thermoelectric materials involve multi-step processes with considerable time and energy consumption. Here we report a fast and one-step way to prepare thermoelectric materials by gas-pressure or high-gravity assisted combustion synthesis. Dense Cu2SnSe3 samples with a porosity below 2% were prepared from self-sustained combustion reaction of element powders. The electrical conductivity of the Cu2SnSe3 samples was greatly enhanced and the thermal conductivity was reduced by partial substitution of Sn with In. The ZT values of the un-doped and In-doped Cu2SnSe3 samples reached 0.51 and 0.62 at 773 K, respectively, which are comparable to the best results reported for Cu2SnSe3 produced by other methods. Combustion synthesis offers an efficient way to prepare thermoelectric materials with reduced time and energy consumption, which may open up new possibilities for synthesis of thermoelectric materials.

A fast and furnace-free way is reported to synthesize ZnSe from self-sustained combustion reaction between Zn and Se. The synthesized ZnSe shows a zincblende structure and large particle size of >100 μm, which can be reduced by two magnitude to 1.4 μm by using NaCl as diluent. It is proposed that the added NaCl can lower the reaction temperature and diminish the interfacial area of ZnSe grains by a steric hindrance effect. The ZnSe samples show the characteristic band-edge absorption in visible region, and the band gap energy is estimated to be 2.43–2.58 eV. Under an ultraviolet excitation, the ZnSe samples do not show the near-band-edge blue emission but exhibit strong red emission, which is likely related to the intrinsic point defects in ZnSe. Compared with previous studies, the ZnSe samples synthesized in this work show red emission peaks at even larger wavelength up to 730 nm. Keywords: Combustion synthesis, Self-propagating high-temperature synthesis, ZnSe, Optical properties

Posttraumatic tendon adhesion limits the motion of the limbs greatly. Biomimetic tendon sheaths have been developed to promote tendon healing and gliding. However, after introduction of these biomaterials, the associated inflammatory responses can decrease the anti-adhesion effect. Celecoxib is a non-steroidal anti-inflammatory drug (NSAID) that can decrease inflammation responses. We blended hyaluronic acid and poly(l-lactic acid)-polyethylene glycol (PELA) with microgel electrospinning technology to form an inner layer of a bi-layer biomimetic sheath using sequential electrospinning of an outer celecoxib-PELA layer. Electrospun bi-layer fibrous membranes were mechanically tested and characterized by morphology, surface wettability, and drug release. The tensile strength showed a decreased trend and water contact angles were 114.7 ± 3.9°, 103.6 ± 4.4°, 116.3 ± 5.1°, 122.8 ± 4.7°, and 126.5 ± 4.2° for the surface of PELA, hyaluronic acid-PELA, 2, 6, and 10% celecoxib-PELA electrospun fibrous membranes, respectively. In vitro drug release studies confirmed burst release and then sustained release from the fibrous membranes containing celecoxib for 20 days. In a chicken model of flexor digitorum profundus tendon surgery, the outer celecoxib/PELA layer offered advanced anti-adhesion roles compared to the outer PELA layer and the inner hyaluronic acid-loaded PELA layer still offered tendon healing and gliding. Thus, celecoxib-loaded anti-adhesive tendon sheaths can continuously offer bi-layer biomimetic tendon sheath effects with celecoxib release from the outer layer to prevent tendon adhesion.

In this work, metal-matrix composites which possess tunable thermal expansion coefficients in combination with high electrical and thermal conductivities were successfully synthesized by a moderate temperature hot-pressing method. The composites are based on incorporating La(Fe, Si, Co)13, a material with a negative coefficient of thermal expansion, within a continuous Cu matrix. The La(Fe, Si, Co)13 enables us to tune the coefficient of thermal expansion in a predictable manner, while the Cu phase is responsible for the electrical and thermal conductivity properties. The resulting materials exhibit coefficients of thermal expansion which can be tuned between the value of pure Cu and La(Fe, Si, Co)13. Thus, by adjusting the relative amount of the two components, the materials can be designed with high electrical and thermal conductivities and tailoring coefficient of thermal expansion properties. This unique combination of electrical and thermal properties enables these Cu-based metal-matrix composites to be applied in the microelectronic, semiconductor and thermoelectric industries.

Thermoelectric materials are attractive for solar thermal energy conversion and waste heat recovery. The preparation of bulk thermoelectric materials usually involves multi-step processes with considerable time and energy consumption. Here we report an alternative way called combustion synthesis to realize one-step and fast fabrication of bulk Cu2ZnSnSe4 thermoelectric materials. The combustion synthesis was carried out in 2 MPa Ar gas atmosphere or in a high-gravity field in order to reduce the porosity in samples and complete simultaneous densification during synthesis. Nearly full-dense Cu2ZnSnSe4 samples with a porosity of

Lead-free polycrystalline SnSe is a promising thermoelectric compound consisting of earth-abundant elements. However, the poor electrical transport property for low intrinsic defect concentration (3 × 1017 cm−3) limits the usage of the stoichiometric SnSe compound. In this work, Na2Se as an acceptor was doped into SnSe in order to optimize the electrical transport properties, especially to increase the carrier concentration. As a result, the carrier concentrations increased and saturated at about 1.0 × 1019 cm−3 for Na0.01Sn0.99Se at 300 K, and a maximum power factor of 0.48 mW m−1 K−2 was obtained. A maximum zT value of 0.75 was obtained at 823 K for Na0.01Sn0.99Se along the direction perpendicular to the sintering pressure, which is 25% higher than that (0.6) of the undoped SnSe compound.

Thermoelectric materials can be used to directly and reversibly convert waste heat into electrical power and have attracted significant attention. Lead-free tin chalcogenide (SnTe, SnSe, SnS) thermoelectric materials are regarded as promising thermoelectric materials due to the great progress in the thermoelectric research field during the past several years. Analogous to PbTe, SnTe has a simple high symmetry NaCl-type cubic structure and a complex band structure, leading to its capability of achieving high thermoelectric performance by band structure and microstructure engineering. SnSe/SnS are simple compounds but exhibit an intrinsically ultralow thermal conductivity, suggesting that a high thermoelectric performance can be realized also in simple layered, anisotropic and anharmonic systems, without nanostructuring. This short perspective summarizes some current strategies that could enhance the thermoelectric performance of bulk lead-free tin chalcogenides, such as band structure engineering, nanostructuring, and synergistically improved approaches. Future possible strategies for further enhancing the thermoelectric performance of tin chalcogenides are also considered at the end of this perspective.

An experimental investigation was conducted to study the thermal performance of a cryogenic pulsating heat pipe (PHP) filled with helium in terms of thermal resistance, effective thermal conductivity and the maximum transferred power. The stainless steel helium PHP in this paper with an inner diameter of 0.5 mm was bent to 8 parallel channels, and the lengths of the evaporator, condenser, and adiabatic section were 50 mm, 50 mm, and 100 mm, respectively. A mechanical–thermal switch worked as a novel pre-cooling system for the helium PHP was developed, which was on during the pre-cooling process and off during the test process. Tests were performed with different heat power, tilt angle and liquid filling ratio. For the helium PHP at +30° with a liquid filling ratio of 70.8%, the effective thermal conductivity was 4800–13,000 W/m K, which was higher than that of copper. With the increment of heat power, the thermal resistance decreased at first and then increased, while the effective thermal conductivities were the opposite. The effective thermal conductivity and the maximum transferred power increased with the increment of the tilt angle. In addition, the helium PHP possessed the optimal liquid filling ratio which could make the maximum thermal conducting effectivity, and the optimal liquid filling ratio changed with the heat power. The optimal liquid ratio, by its very nature, meant reasonable proportion of sensible and latent heat.

Bulk In-doped Cu2SnSe3 samples have been prepared by a fast, one-step method combining the synthesis and sintering process, named high-pressure combustion synthesis (HPCS), and they were also prepared by conventional spark plasma sintering (SPS) for comparison. The relative densities of the In-doped Cu2SnSe3 samples are above 98%, a little higher than the 96% by SPS. The thermodynamic parameters and reaction kinetics of the HPCS process are investigated, showing the maximum combustion temperature of 708 K and combustion wave propagation velocity of 2 mm s−1. The thermoelectric properties of the Cu2Sn1−xInxSe3 samples (HPCS) with x ranging from 0 to 0.20 have been measured in the temperature range of 323–773 K. The electrical conductivity at 323 K is greatly enhanced by almost 6 times from 2.2 × 104 S m−1 to 12.9 × 104 S m−1 by the substitution of Sn with In (x = 0.15). The maximum ZT reaches 0.56 at 773 K for the sample of x = 0.10, which is about 20% higher than that of the unadulterated sample. Compared with the samples prepared by HPCS-SPS, the maximum ZT reaches 1.28 at 823 K for the In doping content of x = 0.10, which is much higher than that for the HPCS samples, attributing to the much lower thermal conductivity caused by strong boundaries scattering. The combustion synthesis offers a fast and more efficient approach for the fabrication of Cu2SnSe3 materials with reduced time and energy consumption.

In this study, well-ordered microscale MCM-41 mesoporous silica sheets of ca. 80 nm thicknesses were first prepared by using water and petroleum ether as cosolvents in the presence of CTAB as template and TEOS as silica precursor. The as-synthesized materials showed excellent bovine serum albumin proteins loading capacity (598 mg protein per gram silica materials), controllable sustained protein release profile, and effective catalytic reduction performance of 4-nitrophenol after high payload of Ag nanoparticles.

We analyzed the 87Sr/86Sr ratios of basaltic rocks and basin water in Xuyi, China, and found a big difference, which may challenge conventional wisdom on the contribution of basalt weathering in end-member analysis. Results of an in-house weathering experiment suggest that rainwater and dust are not responsible for the difference. By isolating the major minerals in basalt, we found that plagioclase has much higher 87Sr/86Sr ratios than bulk basalt and basin water, which might explain the difference in 87Sr/86Sr ratios of basalt and basin water. We infer that low-temperature hydrothermal alteration increased the 87Sr/86Sr ratios of plagioclase. Future analyses of end-member contribution in a mixed-rock basin should take into account that basin water and plagioclase have higher 87Sr/86Sr ratios than basaltic rocks.

Here we present (234U/238U) data from river sediments collected on the Tibetan Plateau. The (234U/238U) ratios of a specific grain size fraction show good correlation with erosion rates, which were determined by in-situ–produced cosmogenic nuclides. This correlation has previously been observed in a wide range of geomorphic settings, suggesting that (234U/238U) ratios of fluvial sediments have great potential to quantify erosion rates.

NaZn13-type La(Fe, M)13-based (M = Si, Al) intermetallic compounds find wide applications, ranging from microelectronics to space technology, because of their significant abnormal thermal expansion (ATE) associated with their huge magnetovolume effect. In this work, element La was partially substituted in LaFe11.2Al1.8 by element Ce to optimize the ATE characteristics of these alloys. The obtained average thermal expansion coefficient (CTE) of La0.8Ce0.2Fe11.2Al1.8 reaches as large as −21.7 × 10−6 K−1 in the temperature range of 100–200 K, which is nearly 25% larger than that of LaFe11.2Al1.8 (−17.31 × 10−6 K−1). Magnetic measurements confirmed that the improved negative thermal expansion (NTE) property is attributed to the enhanced magnetization originating from the magnetic coupling between Ce and Fe atoms. Additionally, smaller negative thermal expansion was observed in La0.4Ce0.6Fe11.2Al1.8 with an average CTE of −1.6 × 10−6 K−1 in a broad operating temperature window from 10 to 170 K. The enhanced NTE values of La(Fe, Al)13-based alloys with partial substitution of Ce for La demonstrated in this work show the potential of their practical applications.

In the present work, fatigue crack propagation behavior of 316LN tungsten inert gas (TIG) weldment and weldment with post weld heat treatment (PWHT) was investigated at liquid helium temperature. Results indicates that the weldment with PWHT results in the highest fatigue crack propagation resistance, whereas the base material demonstrates the lowest fatigue crack propagation resistance. Microstructure evolution reveals that the fatigue crack propagation is characterized as transgranular fracture for the base material as well as the as-welded weldments and the weldment with PWHT. Moreover, the crack propagation path of the weldments shows a zigzag crack extension, especially for the weldment with PWHT, whereas the crack extension of the base material is relative straight. Electron backscattered diffraction reveals more amount of strain-induced martensite near the crack tip in the base material compared to in the as-welded weldment and in the weldment with PWHT, which is considered to be a crucial factor in the fatigue crack propagation behavior at cryogenic temperature.

In the present work, microstructural and microchemical of Nb3Sn strands with the internal tin process produced by the Western Superconductor Technology co., Ltd (WST) and Oxford Instruments co., Ltd (OST) were analyzed. The internal 3D-view of two Nb3Sn strands were detected with a (sub-)micrometric resolution in a non-invasive, non-destructive way, i.e. high-resolution 3D X-ray micro tomography. The distribution of filaments and voids induced by the functional heat treatment of two strands were investigated. The elements distribution after heat reaction of two strands was investigated through elemental mapping by scanning electron microscope (SEM) and energy dispersive X-ray analysis. The filaments of the WST Nb3Sn strand distributed uniformly, whereas the filaments separated with clear copper boundary among filaments. However, the filaments of the OST Nb3Sn strand have serious overlap phenomenon and the copper isolation interface was not clear among filaments. In order to investigate the distinction of microstructure, the selected area electron diffraction was also performed by transmission electron microscopy (TEM) and the results indicated that obvious impurities were observed in the Nb3Sn phase of the WST strand compared to the OST strand.

Control of negative thermal expansion (NTE) is of great importance for various applications of NTE materials. Here, we report an effective way to control both the coefficient of thermal expansion (CTE) and NTE temperature-window in NaZn13-type La(Fe, Co, Al)13 compounds by Al and Co substitutions. Experiments show that the average CTE decreases with the increase in Al content. Besides, the NTE temperature-window shifts toward higher temperature due to Co doping. Further studies of magnetic characterizations reveal that the CTE is strongly correlated with the square of the spontaneous magnetization Ms2(T). Moreover, the NTE temperature-window is influenced by the density of 3d electrons at the Fermi level and the FeI–FeII magnetic exchange interactions. This effective way demonstrated in this work to achieve controllable NTE indicates the potentials in practical applications for NTE materials.

The resistivity of metal materials usually increases as the temperature rises and the temperature coefficient of resistivity (TCR) could be a few thousand (ppm/K). In fact, this would cause trouble to the accurate measuring instrument used in varying temperature conditions. Thus, it is a great challenge to develop materials with a low-temperature coefficient of resistivity (L-TCR). In this paper, we synthesized LaFe13-xSix compounds showing L-TCR behavior. The X-ray powder diffraction (XRD) patterns revealed that the crystal structure of LaFe13-xSix compounds changes from a cubic structure to a tetragonal structure as the Si component rises, and new phases like LaSi2 and FeSi appear. By testing electrical property, we find that the local extremum of the TCR is obtained in LaFe5Al8 compound, which is −54.4 ppm/K over 5–300 K.

The temperature coefficient of resistivity (TCR) was systematically investigated in La (Fe, Al)13 compounds with an Al atomic content from 3.40 to 3.70. We find that the local extremum of the TCR is obtained in LaFe9.45Al3.55, which is −20.914 ppm/K over 5–300 K. It is rare for TCR to stay at such a low level over such a wide temperature range below 300 K. Our work revealed that all compounds remain the same structure of cubic NaZn13-type (space group: Fm3¯c) based on synchrotron radiation X-ray diffraction (SR-XRD) and X-ray powder diffraction (XRD) tests. The magnetization–temperature curves indicate that all samples are ferromagnet. We analyzed the effect of structure on the performance from the perspective of the Fe–Fe atomic distance. These peculiar behaviors are possibly due to the competitive effect by magnetic scattering and e–p scattering.

Epoxy (EP) resin based nano-composites are widely used in high voltage direct current (HVDC) high temperature superconducting (HTS) power cable. In this paper, the DC surface flashover characteristics of ZnO/EP composites were studied at both room temperature and 77 K. The samples were made by dispersing ZnO nano-particles into EP resin with various weight percentages of 0%, 1%, 3%, 6% and 10%, respectively. The experiments were carried out with a cryogenic system in which DC high voltages ranging from 0 kV to 100 kV were supplied. The results showed that the surface flashover voltages increased with the increase of ZnO content at both room temperature and 77 K, and the surface flashover voltages at 77 K were higher than that at room temperature for composites with the same ZnO content.

In the present work, influences of room temperature tensile pre-strain on cryogenic tensile properties of 316LN austenitic stainless steel (SS) were investigated. The tensile properties of the 316LN SS with various tensile pre-straining amounts of 15%, 25% and 35% were measured at both room temperature (RT) and liquid helium temperature (4.2 K). Results indicated that both 0.2% proof strength (Rp0.2) and ultimate tensile strength (Rm) at both RT and 4.2 K of the pre-strained 316LN SS significantly increased compared to those of the as-received material. The Rp0.2 and Rm at 4.2 K for 35% pre-strained specimens increased around 86% and 18%, respectively, compared to those of the as-received material. However, the elongation at fracture (A) at both RT and 4.2 K decreased for the pre-strained 316LN SS compared to those of the as-received material. The fractured morphologies of the pre-strained 316LN SS were investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Dimples in the surface fractured at both RT and 4.2 K of the as-received and pre-strained 316LN exhibited a ductile fracture mode. Moreover, fractographic results indicated that the pre-strain treatment considerably decreased the ductility at both RT and 4.2 K. TEM analyses revealed that pre-strain treatment at RT led to dislocation accumulation and stress-induced martensite phase occurred at 4.2 K, which interpreted the cryogenic tensile properties of the pre-strained 316LN SS.

The present work investigates the influence of Mo additive and aging temperatures on the microstructure and corrosion behavior in 3.5% NaCl solution. The microstructure of (CoCrFeNi)100-xMox(x = 1, 2, 3) alloys aged at 700 °C and 900 °C comprises single FCC solid solution structure. When the Mo content increases from 1% to 2%, the polarization curves and electrochemical impedance spectroscopy in 3.5% NaCl solution indicate that the corrosion resistance of the alloys gradually increases with increasing aging temperature and Mo content. However, the corrosion resistance of (CoCrFeNi)97Mo3 alloy aged at 900 °C decreased suddenly. XPS analysis reveals that the main components of the passive film are Cr2O3 and MoO3, and the intensity of Cr2O3 and MoO3 in the passive film tends to increase with Mo increases from 1% to 2%, which can improve the stability of the passive film. The first-principles calculation was used to understand the effect of Cl− on the pitting mechanism of the passive film.

Usually the tumor thermal therapy is accompanied with inflammatory reactions, which in turn promote tumor growth and metastasis meanwhile. Herein, we prepared novel trifunctional PEG-IL/ZrO2-Ag@SiO2 nanorattles, which can be used for CT imaging-guided simultaneous tumor microwave thermal therapy and resistance to bacterial infection. Under the microwave irradiation, the nanorattles present excellent microwave thermal properties. Simultaneously, the nanorattles have good antibacterial effect in vitro and in vivo, which can restrain bacterial growth effectively and reduce inflammation response during the microwave thermal therapy. In addition, the nanorattles also have the function of CT imaging, which can monitor the tumor therapy in real time. The strategy of simultaneous microwave thermal therapy and inflammation management effectively inhibits tumor growth in mice with a good anti-tumor effect (96.4%). This proof-of-concept investigation provides a simple and reliable strategy for tumor treatment and inhibiting inflammatory reaction using a multifunctional nanomaterial, indicating the great application prospect in tumor treatment by simultaneous eradicating tumor tissue and managing inflammation.

In this work, a new kind of La(Fe, Si, Co) 13 /Cu composite with near zero thermal expansion property was successfully synthesized. The composite shows almost zero thermal expansion with a coefficient of thermal expansion of 0.8 × 10 −6 K −1 in the temperature range of 301–325 K. In addition, the thermal conductivity and electrical resistivity were investigated. Compared with pure La(Fe, Si, Co) 13 materials, the La(Fe, Si, Co) 13 /Cu composite shows significant improvement in both thermal and electrical conductivities. The thermal conductivity of the LaFe 10.5 Co 1.0 Si 1.5 /Cu composite is 25.1 W m −1 K −1 , which is about five times than that of the pure LaFe 10.5 Co 1.0 Si 1.5 . The electrical resistivity reaches 0.16 × 10 −6 Ω m. This offers a new kind of metal matrix composites with low/near zero thermal expansion, high thermal and electrical conductivity properties.

SnSe is a promising thermoelectric material due to its ultralow thermal conductivity. However, stoichiometric SnSe compounds exhibit very low intrinsic defect concentration (3 × 1017 cm−3) and poor electrical transport properties, limiting the thermoelectric performance. In the present work, we investigated the effect of Ag dopant on the thermoelectric properties of SnSe. The results demonstrate that all the AgxSn1−xSe compounds exhibited anisotropic thermoelectric properties. The carrier concentration in the AgxSn1−xSe compounds greatly increased with increase of the Ag content, saturating at 1.9 × 1019 cm−3 for Ag0.01Sn0.99Se at room temperature. We found that a maximum zT value of 0.74 was obtained for Ag0.01Sn0.99Se perpendicular to the pressing direction at 823 K, being 23% higher than that of undoped SnSe (zT = 0.6).

The cubic NaZn 13 -type LaFe 11.2 Al 1.8−x Si x (x = 0.2, 0.3, 0.4 and 0.5) compounds with different Si content were fabricated by conventional arc-melting method, the structures of which were confirmed by powder X-ray diffraction (XRD) measurement at ambient temperature. Besides, the thermal expansion and magnetic properties of these samples were also researched by means of a strain gage and a physical property measurement system (PPMS). Significantly, it was found that the negative thermal expansion (NTE) behavior have been remarkably enhanced with substituting Al with Si atoms. Furthermore, the NTE operation-temperature window concurrently shifts toward a higher temperature region. The variable temperature XRD results indicate that LaFe 11.2 Al 1.8−x Si x retain cubic NaZn 13 -type structure when temperature varies from 20 K to 270 K, including the temperature region where NTE occurs. The further theoretical analysis combined with magnetic characterization reveal that the improvement of NTE behavior is attributed to the enhancement of Fe–Fe magnetic exchange interactions with doping Si atoms. It is noteworthy that this study displays a new pathway to improve the NTE property of La(Fe,Al) 13 -based compounds at low temperature region, which highlights the potential applications of NTE materials in cryogenic engineering.

The part-through fracture toughness ( K Ie ) and crack-tip opening displacement (CTOD, δ m ) of welded joints of aluminum alloy (AA) 20l4-T6, including the weld metal, the fusion zone (FZ), the heat-affected zone (HAZ), and the base material, were investigated at both liquid nitrogen temperature and liquid helium temperature with surface-crack tension (SCT) specimen and single-edge-notched bend (SENB) specimen respectively. Results indicate a conventional fusion welding process leads to formation of second-phase precipitations and inclusions, which cause significant reduction of fracture resistance at the weld metal and the FZ by fractographic analyses of fractured surface.

Isotropic negative area compressibility, which is very rare, is observed in KBBF and the related mechanism is investigated by combined high-pressure X-ray diffraction (XRD) experiments and first-principles calculations. The strong mechanical anisotropy leads to a large Poisson's ratio and high figure of merit for the acoustic-optics effect, giving KBBF potential applications as smart strain converters and deep-ultraviolet (DUV) acoustic-optic devices.

Small-scale helium liquefiers using regenerative cryocoolers with cooling power up to 1.5 W at 4.2 K could be used to re-liquefy evaporated helium gas of small- and medium-sized cryogenic devices such as MEG and PPMS. A serial–parallel-path helium liquefier with a liquefaction rate of 83 Litres per day (L/d) using five 4 K G-M cryocoolers is developed, and has been applied to the Wuhan National High Magnetic Field Center (WHMFC) in China. Different from parallel-path helium liquefier, the helium gas is effectively, stepwise precooled by heat exchangers on multi-cold flanges, and thus the additional purifier and precooling coil heat exchangers on the thinner part of the cold head cylinder containing the 2nd stage displacer could be removed to simplify the construction. Through theoretical calculation and conclusive analysis, an optimum configuration is proposed and makes a reference to the design of serial–parallel-path helium liquefier with multi-cryocoolers.

Using spark plasma sintering (SPS), Mn3Cu0.6Ge0.4N crystallites have been fabricated with different crystallite sizes, and their magnetic properties and thermal behaviors were systemically investigated. With decreasing crystallite size, the magnetic transition becomes increasingly slow, accompanied by broadening of the negative thermal expansion (NTE) operation-temperature window. The NTE operation-temperature window for the 12-nm crystallite sample reaches at 140 K, which is about 75% larger than that of the 74-nm crystallite sample. The magnetic properties and NTE operation-temperature window can be tuned by varying the crystallite size. This discovery will promote an even wider range of practical applications in precision devices.

The antiperovskite Mn3+xNi1–xN compounds have been synthesized and characterized by a variety of experimental techniques. After Mn doping at the Ni site, both ferromagnetic characteristics and an Invar-like effect were observed in the antiferromagnetic host material. The observed Invar-like behavior was assumed to be related to the characteristic magnetic structure induced by the doping. Neutron diffraction results prove that the Mn doping stabilizes the special Γ5g antiferromagnetic phase with strong spin–lattice coupling that can be tuned to achieve Invar-like behavior. The magnetovolume effect (MVE) and significant correlation between spin and lattice were confirmed for the Γ5g magnetic phase by the first-principles calculations. Moreover, Mn 3d electrons were revealed to be the key factor for the MVE from the calculations. Our study presents a new mechanism for precisely controlling the zero thermal expansion of a single compound by achieving the special Γ5g magnetic phase of Mn atoms.

High performance heat exchangers are critical component in many cryogenic systems and its performance is typically very sensitive to longitudinal heat conduction, parasitic heat loads and property variations. This paper gives an analytical study on 1-D model for multi-stream parallel-plate fin heat exchanger by using the method of decoupling transformations. The results obtained in the present paper are valuable for the reference on optimization for heat exchanger design.

Solid solution is a potential way to optimize thermoelectric performance for its low thermal conductivity compared to those of the constituent compounds because of the phonon scattering from disordered atoms. Tin(II) sulfide (SnS) shows analogous band structure and electrical properties with tin selenide (SnSe), which was the motivation for investigating the thermoelectric performance of SnS and SnS–SnSe solid solution system. SnS compound and SnS1−xSex (0 < x < 1) solid solution were fabricated using the melting method and they exhibited anisotropic thermoelectric performance along the parallel and perpendicular to the pressing directions. For the SnS compound, the maximum zT∥ value is 0.19 at 823 K along the parallel to pressing direction, which is higher than that along the perpendicular to the pressing direction (zT⊥ = 0.16). The zT values of SnS0.5Se0.5 and SnS0.2Se0.8 were higher than those of the SnS compound and a maximum zT value of 0.82 was obtained for SnS0.2Se0.8 at 823 K, which is more than four times higher than that of SnS.

A 150 kJ high temperature superconducting magnetic energy storage (HTS-SMES) system is under manufacturing in China. This paper focuses on the structural design and analysis of the SMES cryogenic system. The cryogenic system is designed and fabricated to maintain the working temperature. The system includes a vacuum vessel, its thermal radiation shield, its supporting devices, conduction plates, and current leads. Two G-M cryocoolers are used for the system cooling, the main one is connected to the HTS coils and the other is connected to the thermal shield and the lower ends of the current leads. In this study, the 3D models of the SMES cryogenic system were created with CATIA, a 3D model design software, and the analysis of the SMES cryogenic system was done by ANSYS. The mechanical analysis results on the vacuum vessel, suspension devices and supporting devices are presented, particularly the analyses on suspenders and shelf supports are of vital importance since the finished SMES system should meet vehicle-mounted requirements in long time transport. The heat load and the temperature distribution of the thermal shield were analyzed. A cooling experiment of the cryogenic system was made and the thermal shield was cooled down to about 50 K.

The negative thermal expansion (NTE) performance and correlated structure and magnetism for Si-doped Mn 3 Cu 1− x Si x N ( x =0.1–0.5) are investigated. It is found that the NTE behavior appears below room temperature, the absolute value of coefficient of NTE (| α |) tends to be zero and the Curie temperature ( T c ) raises rapidly as the increase of Si content. The tendency of T N temperature depending on Si contents implies that the valence electrons of Si atoms can partially be donated into Mn 3d –N 2p bond. Another important finding is that positive thermal expansion (PTE), NTE and zero thermal expansion (ZTE) are alternatively appeared by improving the Si content. The present work proposes a novel route to design the low-temperature devices using adjustable NTE or ZTE performance by making use of antiperovskite Mn 3 AN materials.