Endocrine regulation of male fertility by the skeleton.

Interactions between bone and the reproductive system have until now been thought to be limited to the regulation of bone remodeling by the gonads. We now show that, in males, bone acts as a regulator of fertility. Using coculture assays, we demonstrate that osteoblasts are able to induce testosterone production by the testes, though they fail to influence estrogen production by the ovaries. Analyses of cell-specific loss- and gain-of-function models reveal that the osteoblast-derived hormone osteocalcin performs this endocrine function. By binding to a G protein-coupled receptor expressed in the Leydig cells of the testes, osteocalcin regulates in a CREB-dependent manner the expression of enzymes that is required for testosterone synthesis, promoting germ cell survival. This study expands the physiological repertoire of osteocalcin and provides the first evidence that the skeleton is an endocrine regulator of reproduction.

Multifunctional Catalytic Hierarchical Interfaces of Ni12 P5 -Ni2 P Porous Nanosheets Enabled Both Sulfides Reaction Promotion and Li-Dendrite Suppression for High-Performance Li-S Full Batteries.

The development of lithium-sulfur (Li-S) batteries is very promising and yet faces the issues of hindered polysulfides conversion and Li dendrite growth. Different from using different materials strategies to overcome these two types of problems, here multifunctional catalytic hierarchical interfaces of Ni12 P5 -Ni2 P porous nanosheets formed by Ni2 P partially in situ converted from Ni12 P5 are proposed. The unique electronic structure in the interface endows Ni12 P5 -Ni2 P effective electrocatalysis effect toward both sulfides' reduction and oxidation through reducing Gibbs free energies, indicating a bidirectional conversion acceleration. Importantly, Ni12 P5 -Ni2 P porous nanosheets with hierarchical interfaces also reduced the Li nucleation energy barrier, and a dendrite-free Li deposition is realized during the overall Li deposition and stripping steps. To this end, Ni12 P5 -Ni2 P decorated carbon nanotube/S cathode showing a high capacity of over 1500 mAh g-1 , and a high rate capability of 8 C. Moreover, the coin full cell delivered a high capacity of 1345 mAh g-1 at 0.2 C and the pouch full cell delivered a high capacity of 1114 mAh g-1 at 0.2 C with high electrochemical stability during 180° bending. This work inspires the exploration of hierarchical structures of 2D materials with catalytically active interfaces to improve the electrochemistry of Li-S full battery.

2D Tellurium Films Based Self-Drive Near Infrared Photodetector.

To reduce the amount of energy consumed in integrated circuits, high efficiency with the lowest energy is always expected. Self-drive device is one of the options in the pursuit of low power nanodevices. It is a typical strategy to form an internal electric field by constructing a heterojunction in self-drive semiconductor system. Here, a two-step method is proposed to prepare high quality centimeter-sized 2D tellurium (Te) thin film with hall mobility as high as 37.3 cm2 V-1 s-1, and the 2D Te film is further assembled with silicon to form a heterojunction for self-drive photodetector, which can realize effective detection from visible to near infrared bands. The photodetectivity of the heterojunctions can reach 1.58×1011 Jones under the illumination of 400 nm@ 1.615 mW/cm2 and 2.08×108 Jones under the illumination of 1550 nm@ 1.511 mW/cm2 without bias. Our experiments demonstrate the potential of 2D tellurium thin films for wide band and near infrared integrated device applications.

Magnetic Field-driven Insulator-Metal Transition and Colossal Magnetoresistance of Metamagnetic Semiconductor Mercury Thiodichromite Crystals.

A facile method is developed to efficiently prepare metamagnetic mercury thiodichromite (HgCr2S4, HCS) polycrystals and single crystals, and their transport properties are studied. The resistivity of the as-prepared HCS polycrystal shows a semiconducting behavior and no magnetic field dependence in the whole temperature range. In contrast, the annealing treatment of the HCS polycrystal induces gigantic changes: an insulator-metal transition is driven by a magnetic field of 5 T, leading to colossal magnetoresistance (CMR) as high as ∼104. The HCS single crystal grown by a newly developed facile method displays similar properties with a larger CMR up to 106-107. First-principles calculation demonstrates a large spin splitting of band structures, providing the possibility of magnetic polaron existence, which is further evidenced by electron spin resonance spectra. Thus, the insulator-metal transition and CMR can be explained in a magnetic polaronic scenario. This work opens a new window for CMR-based spintronics.

Tuning the magnetic properties of van der Waals Fe3GaTe2 crystals by Co doping.

Tuning the magnetic properties of two-dimensional van der Waals ferromagnets has special importance for their practical applications. Using first-principles calculations, we investigate the magnetic properties of Co-doped Fe3GaTe2 with different Co concentrations and different Co atomic sites. Calculation results show that Fe or Co atoms with relatively lower atomic concentrations preferentially occupy Fe1 sites with interlayer coupling, which is more energetically favorable. As the doping concentration of Co atoms increases, the total magnetic moment of the doped system decreases, while the average atomic magnetic moments of Fe1 and Fe2 increase and decrease, respectively, with Fe1 reaching ∼2.08µB. The spin polarization of the doped model 2Co-2 near the Fermi energy level is significantly reduced, while 4Co-3 exhibits an enhanced trend. At some doping level, a phase change from ferromagnetism to antiferromagnetism appears at high Co concentration. These results provide a theoretical basis for experimental studies and valuable information for the development of Fe3GaTe2-based spintronic devices.

ZrTe2 Compound Dirac Semimetal Contacts for High-Performance MoS2 Transistors.

Recent investigations reveal elemental semimetal (Bi and Sb) contacts fabricated with conventional deposition processes exhibit a remarkable capacity of approaching the quantum limit in two-dimensional (2D) semiconductor contacts, implying it might be an optimal option to solve the contact issue of 2D semiconductor electronics. Here, we demonstrate novel compound Dirac semimetal ZrTe2 contacts to MoS2 constructed by a nondestructive van der Waals (vdW) transfer process, exhibiting excellent ohmic contact characteristics with a negligible Schottky barrier. The band hybridization between ZrTe2 and MoS2 was verified. The bilayer MoS2 transistor with a 250 nm channel length on a 20 nm thick hexagonal boron nitride (h-BN) exhibits an ION/IOFF current ratio over 105 and an on-state current of 259 µA µm-1. The current results reveal that 2D compound semimetals with vdW contacts can offer a diverse selection of proper semimetals with adjustable work functions for the next-generation 2D-based beyond-silicon electronics.

Rare Earth Single-Atom Catalysis for High-Performance Li-S Full Battery with Ultrahigh Capacity.

Lithium-sulfur (Li-S) batteries have many advantages but still face problems such as retarded polysulfides redox kinetics and Li dendrite growth. Most reported single atom catalysts (SACs) for Li-S batteries are based on d-band transition metals whose d orbital constitutes active valence band, which is inclined to occur catalyst passivation. SACs based on 4f inner valence orbital of rare earth metals are challenging for their great difficulty to be activated. In this work, we design and synthesize the first rare earth metal Sm SACs which has electron-rich 4f inner orbital to promote catalytic conversion of polysulfides and uniform deposition of Li. Sm SACs enhance the catalysis by the activated 4f orbital through an f-d-p orbital hybridization. Using Sm-N3C3 modified separators, the half cells deliver a high capacity over 600 mAh g-1 and a retention rate of 84.3 % after 2000 cycles. The fabricated Sm-N3C3-Li|Sm-N3C3@PP|S/CNTs full batteries can provide an ultra-stable cycling performance of a retention rate of 80.6 % at 0.2 C after 100 cycles, one of the best full Li-S batteries. This work provides a new perspective for the development of rare earth metal single atom catalysis in electrochemical reactions of Li-S batteries and other electrochemical systems for next-generation energy storage.

Two-Dimensional Van Der Waals Topological Materials: Preparation, Properties, and Device Applications.

Over the past decade, 2D van der Waals (vdW) topological materials (TMs), including topological insulators and topological semimetals, which combine atomically flat 2D layers and topologically nontrivial band structures, have attracted increasing attention in condensed-matter physics and materials science. These easily cleavable and integrated TMs provide the ideal platform for exploring topological physics in the 2D limit, where new physical phenomena may emerge, and represent a potential to control and investigate exotic properties and device applications in nanoscale topological phases. However, multifaced efforts are still necessary, which is the prerequisite for the practical application of 2D vdW TMs. Herein, this review focuses on the preparation, properties, and device applications of 2D vdW TMs. First, three common preparation strategies for 2D vdW TMs are summarized, including single crystal exfoliation, chemical vapor deposition, and molecular beam epitaxy. Second, the origin and regulation of various properties of 2D vdW TMs are introduced, involving electronic properties, transport properties, optoelectronic properties, thermoelectricity, ferroelectricity, and magnetism. Third, some device applications of 2D vdW TMs are presented, including field-effect transistors, memories, spintronic devices, and photodetectors. Finally, some significant challenges and opportunities for the practical application of 2D vdW TMs in 2D topological electronics are briefly addressed.

Highly Tunable Beyond-Room-Temperature Intrinsic Ferromagnetism in Cr-Doped Topological Crystalline Insulator SnTe Crystals.

The combination of topological phase and intrinsic beyond-room-temperature ferromagnetism is expected to realize the quantum anomalous Hall effect at a high temperature. However, no beyond-room-temperature intrinsic ferromagnetism has been reported in either topological insulator or topological crystalline insulator (TCI) so far. Here, we report Cr-doping in TCI-phase SnTe crystals which possess highly tunable beyond-room-temperature intrinsic ferromagnetism including Tc, magnetic moment, and coercivity by varying Cr contents and crystal thickness. With the increase of the Cr content, the Tc increases by 159 K from 221 to 380 K and the saturation magnetic moments increase by ∼23.6 times from 0.018 to 0.421 µB/f.u. This intrinsic beyond-room-temperature ferromagnetism is fully demonstrated by the anomalous Hall effect and magneto-optical Kerr effect in a single CrxSn1-xTe nanosheet. Moreover, the room-temperature tunneling magnetoresistance effect has been realized by using a CrxSn1-xTe flake, a Fe thin film, and a commercially compatible ultrathin AlOx tunneling barrier. This work indicates a great potential of CrxSn1-xTe crystals in room-temperature magnetoelectronic and spintronic devices.

Hierarchical nitrogen-doped porous graphene/reduced fluorographene/sulfur hybrids for high-performance lithium-sulfur batteries.

It is a great challenge to obtain high performance cathodes with a high sulfur loading and good cycle performance due to the dissolution of intermediate lithium polysulfides in lithium-sulfur batteries. Herein, we report a novel hierarchical hybrid composed of nitrogen-doped porous graphene (NG), reduced fluorographene or graphene fluoride (RFG), and sulfur as a composite cathode in the Li-S batteries. In comparison with sulfur composites based on only either nitrogen-doped porous graphene or pure reduced fluorographene, the hierarchical hybrid of RFG, NG, and sulfur (NG-RFG/S) shows a better reversible capacity and rate capability performance due to a better confinement effect of lithium polysulfides and sulfur. The NG-RFG/S cathode with ∼63.2% S content exhibits a high discharge capacity of 1120 mA h g-1 and retains 632 mA h g-1 after 100 cycles at 0.1C. At the higher rate of 0.5C, the cell still maintains a discharge capacity of about 300 mA h g-1 after 800 cycles, which reveals the great potential of this hybrid cathode for long-cycle-life, high energy density storage applications.

Engineered nanomembranes for directing cellular organization toward flexible biodevices.

Controlling the cellular microenvironment can be used to direct the cellular organization, thereby improving the function of synthetic tissues in biosensing, biorobotics, and regenerative medicine. In this study, we were inspired by the microstructure and biological properties of the extracellular matrix to develop freestanding ultrathin polymeric films (referred as "nanomembranes") that were flexible, cell adhesive, and had a morphologically tailorable surface. The resulting nanomembranes were exploited as flexible substrates on which cell-adhesive micropatterns were generated to align C2C12 skeletal myoblasts and embedded fibril carbon nanotubes enhanced the cellular elongation and differentiation. Functional nanomembranes with tunable morphology and mechanical properties hold great promise in studying cell-substrate interactions and in fabricating biomimetic constructs toward flexible biodevices.

Robust Magnetic Proximity Induced Anomalous Hall Effect in a Room Temperature van der Waals Ferromagnetic Semiconductor Based 2D Heterostructure.

Developing novel high-temperature van der Waals ferromagnetic semiconductor materials and investigating their interface coupling effects with 2D topological semimetals are pivotal for advancing next-generation spintronic and quantum devices. However, most van der Waals ferromagnetic semiconductors exhibit ferromagnetism only at low temperatures, limiting the proximity research on their interfaces with topological semimetals. Here, an intrinsic, van der Waals layered room-temperature ferromagnetic semiconductor crystal, FeCr0.5 Ga1.5 Se4 (FCGS), is reported with a Curie temperature (TC ) as high as 370 K, setting a new record for van der Waals ferromagnetic semiconductors. The saturation magnetization at low temperature (2 K) and room temperature (300 K) reaches 8.2 and 2.7 emu g-1 , respectively. Furthermore, FCGS possesses a bandgap of ≈1.2 eV, which is comparable to the widely used commercial silicon. The FCGS/graphene 2D heterostructure exhibits an impeccably smooth and gapless interface, thereby inducing a robust van der Waals magnetic proximity coupling effect between FCGS and graphene. After the proximity coupling, graphene undergoes a charge carrier transition from electrons to holes, accompanied by a transition from non-magnetic to ferromagnetic transport behavior with robust anomalous Hall effect (AHE). Notably, the van der Waals magnetic proximity-induced AHE remains robust even up to 400 K.

Halide solid-state electrolytes for all-solid-state batteries: structural design, synthesis, environmental stability, interface optimization and challenges.

Since the huge breakthrough in 2018, research on halide solid-state electrolytes (SSEs) has set off a new craze. In comparison with oxide and sulfide SSEs, halide SSEs have more balanced properties in various aspects, including ionic conductivity, electrochemical stability window, and moisture resistance. Herein, the overall knowledge and deep understanding of halide SSEs and their practical applications in all-solid-state batteries (ASSBs) are introduced. Firstly, the principle of screening halide SSE components is proposed. Among F, Cl, Br and I anions, the Cl anion is excellent owing to its suitable ionic conductivity and electrochemical stability window. The Sc, Y, and lanthanide elements are also more compatible with Cl anions in terms of electronegativity. Secondly, the structural design theory of halide SSEs with high ionic conductivity and the mechanism of Li ion migration are described. A monoclinic structure is more conducive to Li ion migration, compared with trigonal and orthorhombic structures. Additionally, substitution strategies for halide SSEs are discussed, mainly including dual-halogen, isovalent cation substitution, and aliovalent cation substitution. Furthermore, the mechanism of moisture resistance and synthesis method of halide SSEs are analyzed. Compared with the solid-state reaction and mechanochemistry method, wet chemical synthesis is more likely to achieve scale-up production of halide SSEs. Finally, the application prospects and challenges of halide SSEs in ASSBs are outlined.

Room-Temperature and Tunable Tunneling Magnetoresistance in Fe3GaTe2-Based 2D van der Waals Heterojunctions.

Magnetic tunnel junctions (MTJs) based on van der Waals (vdW) heterostructures with sharp and clean interfaces on the atomic scale are essential for the application of next-generation spintronics. However, the lack of room-temperature intrinsic ferromagnetic crystals with perpendicular magnetic anisotropy has greatly hindered the development of vertical MTJs. The discovery of room-temperature intrinsic ferromagnetic two-dimensional (2D) crystal Fe3GaTe2 has solved the problem and greatly facilitated the realization of practical spintronic devices. Here, we demonstrate a room-temperature MTJ based on a Fe3GaTe2/WS2/Fe3GaTe2 heterostructure for the first time. The tunneling magnetoresistance (TMR) ratio is up to 213% with a high spin polarization of 72% at 10 K, the highest ever reported in Fe3GaTe2-based MTJs up to now. A tunneling spin-valve signal robustly persists at room temperature (300 K) with a bias current down to 10 nA. Moreover, the spin polarization can be modulated by bias current and the TMR shows a sign reversal at a large bias current. Our work sheds light on the potential application of low-energy consumption in all-2D vdW spintronics and offers alternative routes for the electronic control of spintronic devices.

Room-temperature spin-valve devices based on Fe3GaTe2/MoS2/Fe3GaTe2 2D van der Waals heterojunctions.

The spin-valve effect has been the focus of spintronics over the last decades due to its potential for application in many spintronic devices. Two-dimensional (2D) van der Waals (vdW) materials are highly efficient to build spin-valve heterojunctions. However, the Curie temperatures (TC) of the vdW ferromagnetic (FM) 2D crystals are mostly below room temperature (∼30-220 K). It is very challenging to develop room-temperature, FM 2D crystal-based spin-valve devices. Here, we report room-temperature, FM 2D-crystal-based all-2D vdW Fe3GaTe2/MoS2/Fe3GaTe2 spin-valve devices. The magnetoresistance (MR) of the device was up to 15.89% at 2.3 K and 11.97% at 10 K, which are 4-30 times the MR of the spin valves of Fe3GeTe2/MoS2/Fe3GeTe2 and conventional NiFe/MoS2/NiFe. The typical spin valve effect showed strong dependence on the MoS2 spacer thickness in the vdW heterojunction. Importantly, the spin valve effect (0.31%) robustly existed even at 300 K with low working currents down to 10 nA (0.13 A cm-2). This work provides a general vdW platform to develop room-temperature, 2D FM-crystal-based 2D spin-valve devices.

MASCN Surface Treatment to Reduce Phase Transition Temperature and Regulate Strain for Efficient and Stable α-FAPbI3 Perovskite Solar Cells.

The fabrication of α-FAPbI3 perovskite films usually requires high temperature annealing above 150 °C, and the residual tensile strain in the films seriously affects the stability of α-FAPbI3 by converting to δ-phase FAPbI3. Here, we use MASCN surface treatment of FAPbI3 films to induce a rotation of the coplanar octahedron [PbI6]4- to the metric octahedron for the strong interaction of SCN- with Pb2+, converting δ-FAPbI3 into α-FAPbI3 highly crystalline films at room temperature. The optimized FAPbI3 films have high stability due to releasing residual tensile strains after MASCN treatment. The efficiency of the MASCN-treated unannealed FAPbI3 PSC is 19.03%, while the optimized FAPbI3 annealed at 100 °C shows a maximum PCE of 21.95% on a small area. The solar cell stability for humidity, light, and thermal stability are significantly improved. The MASCN treated FAPbI3 achieves a PCE of 15.32% on a PSC module with an effective area of 9.6 cm2 and maintains an initial efficiency of 94.1% after 100 days of ageing at 85 °C and 85% humidity.

Nano-biosensor for SARS-CoV-2/COVID-19 detection: methods, mechanism and interface design.

The epidemic of coronavirus disease 2019 (COVID-19) was a huge disaster to human society. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which led to COVID-19, has resulted in a large number of deaths. Even though the reverse transcription-polymerase chain reaction (RT-PCR) is the most efficient method for the detection of SARS-CoV-2, the disadvantages (such as long detection time, professional operators, expensive instruments, and laboratory equipment) limit its application. In this review, the different kinds of nano-biosensors based on surface-enhanced Raman scattering (SERS), surface plasmon resonance (SPR), field-effect transistor (FET), fluorescence methods, and electrochemical methods are summarized, starting with a concise description of their sensing mechanism. The different bioprobes (such as ACE2, S protein-antibody, IgG antibody, IgM antibody, and SARS-CoV-2 DNA probes) with different bio-principles are introduced. The key structural components of the biosensors are briefly introduced to give readers an understanding of the principles behind the testing methods. In particular, SARS-CoV-2-related RNA mutation detection and its challenges are also briefly described. We hope that this review will encourage readers with different research backgrounds to design SARS-CoV-2 nano-biosensors with high selectivity and sensitivity.

Room-Temperature van der Waals Ferromagnet Switching by Spin-Orbit Torques.

The emerging wide varieties of the van der Waals (vdW) magnets with atomically thin and smooth interfaces hold great promise for next-generation spintronic devices. However, due to the lower Curie temperature of the vdW ferromagnets than room temperature, electrically manipulating its magnetization at room temperature has not been realized. In this work, it is demonstrated that the perpendicular magnetization of the vdW ferromagnet Fe3 GaTe2 can be effectively switched at room temperature in the Fe3 GaTe2 /Pt bilayer by spin-orbit torques (SOTs) with a relatively low current density of 1.3 × 107 A cm-2 . Moreover, the high SOT efficiency of ξDL ≈ 0.28 is quantitatively determined by harmonic measurements, which is higher than those in Pt-based heavy metal/conventional ferromagnet devices. The findings of room-temperature vdW ferromagnet switching by SOTs provide a significant basis for the development of vdW-ferromagnet-based spintronic applications.

Unexpected flagellar movement patterns and epithelial binding behavior of mouse sperm in the oviduct.

In order to better understand how sperm movement is regulated in the oviduct, we mated wild-type female mice with Acr-EGFP males that produce sperm with fluorescent acrosomes. The fluorescence improved our ability to detect sperm within the oviduct. Oviducts were removed shortly before or after ovulation and placed in chambers on a warm microscope stage for video recording. Hyperactivated sperm in the isthmic reservoir detached frequently from the epithelium and then reattached. Unexpectedly, most sperm found in the ampulla remained bound to epithelium throughout the observation period of several minutes. In both regions, most sperm produced deep flagellar bends in the direction opposite the hook of the sperm head. This was unexpected, because mouse sperm incubated under capacitating conditions in vitro primarily hyperactivate by producing deep flagellar bends in the same direction as the hook of the head. In vitro, sperm that are treated with thimerosal to release Ca(2+) from internal stores produce deep anti-hook bends; however, physical factors such as viscous oviduct fluid could also have influenced bending in oviductal sperm. Some sperm detached from epithelium in both the ampulla and isthmus during strong contractions of the oviduct. Blockage of oviduct contractions with nicardipine, however, did not stop sperm from forming a storage reservoir in the isthmus or prevent sperm from reaching the ampulla. These observations indicate that sperm continue to bind to oviductal epithelium after they leave the isthmic reservoir and that sperm motility is crucial in the transport of sperm to the fertilization site.

Vanadium nitride nanoparticle decorated N-doped carbon nanotube/N-doped carbon nanosheet hybrids via a C3N4 self-sacrificing method for electrochemical capacitors.

Owing to the wide negative potential window (∼1.2 V) along with high specific capacitance (1340 F g-1) in alkaline electrolyte, vanadium nitride (VN) has been served as promising negative supercapacitor electrode material. However, VN is easy to dissolve during cycling process and shows low capacitance retainability. Herein, a hybrid electrode (marked as VN/NCNT/NCN), featuring VN nanoparticles and N-doped carbon nanotube inserted in N-doped carbon nanosheets, has been fabricated with a facile C3N4 self-sacrificing method. The porous structure and high conductive carbon skeleton, as well as the uniform distribution of VN nanoparticles give VN/NCNT/NCN a great amount of active site and fulfill excellent electrochemical performance for VN/NCNT/NCN-based electrode. The as-fabricated hybrid electrode exhibits a maximum specific capacitance of 232.9 F g-1 at 1 A g-1. Moreover, the cycling performance has been greatly improved and the specific capacitance remains 91% after 5000 cycles.