Metal telluride nanosheets by scalable solid lithiation and exfoliation.

Transition metal tellurides (TMTs) have been ideal materials for exploring exotic properties in condensed-matter physics, chemistry and materials science1-3. Although TMT nanosheets have been produced by top-down exfoliation, their scale is below the gram level and requires a long processing time, restricting their effective application from laboratory to market4-8. We report the fast and scalable synthesis of a wide variety of MTe2 (M = Nb, Mo, W, Ta, Ti) nanosheets by the solid lithiation of bulk MTe2 within 10 min and their subsequent hydrolysis within seconds. Using NbTe2 as a representative, we produced more than a hundred grams (108 g) of NbTe2 nanosheets with 3.2 nm mean thickness, 6.2 µm mean lateral size and a high yield (>80%). Several interesting quantum phenomena, such as quantum oscillations and giant magnetoresistance, were observed that are generally restricted to highly crystalline MTe2 nanosheets. The TMT nanosheets also perform well as electrocatalysts for lithium-oxygen batteries and electrodes for microsupercapacitors (MSCs). Moreover, this synthesis method is efficient for preparing alloyed telluride, selenide and sulfide nanosheets. Our work opens new opportunities for the universal and scalable synthesis of TMT nanosheets for exploring new quantum phenomena, potential applications and commercialization.

Unveiling aging dynamics in the hematopoietic system insights from single-cell technologies.

As the demographic structure shifts towards an aging society, strategies aimed at slowing down or reversing the aging process become increasingly essential. Aging is a major predisposing factor for many chronic diseases in humans. The hematopoietic system, comprising blood cells and their associated bone marrow microenvironment, intricately participates in hematopoiesis, coagulation, immune regulation and other physiological phenomena. The aging process triggers various alterations within the hematopoietic system, serving as a spectrum of risk factors for hematopoietic disorders, including clonal hematopoiesis, immune senescence, myeloproliferative neoplasms and leukemia. The emerging single-cell technologies provide novel insights into age-related changes in the hematopoietic system. In this review, we summarize recent studies dissecting hematopoietic system aging using single-cell technologies. We discuss cellular changes occurring during aging in the hematopoietic system at the levels of the genomics, transcriptomics, epigenomics, proteomics, metabolomics and spatial multi-omics. Finally, we contemplate the future prospects of single-cell technologies, emphasizing the impact they may bring to the field of hematopoietic system aging research.

Honeycomb-ring hybrid random mesh design with electromagnetic interference (EMI) shielding for low stray light.

A honeycomb-ring hybrid random mesh structure is designed to achieve low stray light performance. The honeycomb-ring hybrid random mesh comprises the random honeycomb and random ring, achieving two random superpositions in the structure distribution. The stray light distribution is very low by the combination design with different random hybrid structures. In order to illustrate the advantages of the hybrid random structure, we design a random honeycomb network by randomly offsetting vertices. At the same time, for the random honeycomb structure, we replace each vertex with the ring structure with the size of the ring randomly controlled. Thus, the corresponding honeycomb-ring hybrid random structure is obtained. Compared with the random honeycomb, the maximal normalized high-order diffraction energy of the honeycomb-ring hybrid random mesh is about a 62.85% drop, and the shielding performance is increased by about 50%. At the same time, the optical transmittance remains nearly unchanged. Due to the enjoyable property of the designed honeycomb-ring hybrid random mesh, a sample was prepared for performance verification. The measurement results show that it achieves eminent diffraction pattern distribution with the maximal normalized high-order diffraction energy of about -31.8 dB. At the same time, the average optical transmittance exceeds 86%, and the electromagnetic shielding effectiveness (SE) in the Ku band is greater than 26 dB. Based on the fine photoelectric performance of the honeycomb-ring hybrid random mesh structure, it has great application potential for high-quality optical windows.

Broadband transparent and high-Q resonant polarization meta-grating enabled by a non-local geometric-phase metasurface.

Spatial wavefront control and high-Q spectral filtering are both of great importance for various optical applications, such as eye-tracking for eyewear, planar optical modulators, and optical sensing. However, it is a great challenge to simultaneously satisfy these two functionalities in a metasurface due to the inevitable conflicts of local and non-local modes, where local modes of a single meta-atom manipulate the wavefront in a broadband range, while non-local collective modes of extended meta-atoms only support high-Q resonances at certain characteristic wavelengths. Here, we demonstrate a low-contrast dielectric non-local meta-grating that provides both spatial and spectral control of light in a broadband range of 700-1600 nm, offering elaborate wavefront shaping only for narrow-band resonances. Such counterintuitive functionality is supported by spatially tailored dark modes (quasi-bound states in the continuum) encoding with spatially varying geometric phases, while low-contrast dielectric provides broadband non-resonant transmission. Moreover, a broadband transparent polarization meta-grating with two resonance wavelengths is presented. Non-local geometric-phase metasurfaces open an exciting avenue for wavefront shaping and spectral manipulation, and may have potential applications in sensing, lasing, and spectral filtering.

Sensitivity enhancement of far-detuned RF field sensing based on Rydberg atoms dressed by a near-resonant RF field.

Rydberg-atom electrometers promise traceable standards for RF electrometry by enabling stable and uniform measurement. In this Letter, we propose an approach to increase the sensitivity of the Rydberg-atom electrometer for far-detuned RF field sensing. The key physical mechanism is the addition of a new ingredient-a local RF field near-resonant with a Rydberg transition-so that the far-detuned field can be detected by the shift of an Autler-Townes (AT) splitting peak, which can be dozens of times larger than the AC Stark shift of the electromagnetic induced transparency (EIT) signal without the near-resonant field. The method enables us to measure far-detuned fields with higher sensitivities, including sub-GHz RF fields (even DC electric fields) which are rarely involved in the existing sensitivity enhancement methods.

A Thermal-Switchable Metamaterial Absorber Based on the Phase-Change Material of Vanadium Dioxide.

This article presents a thermal-switchable metamaterial absorber (TSMA) based on the phase-change material of vanadium dioxide (VO2). VO2 thin film was deposited on sapphire substrate by magnetron sputtering followed by vacuum annealing treatment. Then, the prepared VO2 film was sliced into tiny chips for thermal-switchable elements. The surface structure of TSMA was realized by loading four VO2 chips into a square metallic loop. The absorption frequency of TSMA was located at 7.3 GHz at room temperature and switched to 6.8 GHz when the temperature was heated above the critical phase transition temperature of VO2. A VO2-based TSMA prototype was fabricated and measured to verify this design. The design is expected to be used in metasurface antennas, sensors, detectors, etc.

Constant polarization generation metasurface for arbitrarily polarized light.

State of polarization (SoP) of light is one of the fundamental characteristics of light and has great significance to optical communication, imaging, quantum optics and medical facilities. The generation and maintenance of polarized light have always been research concerns in polarization optics. Polarization-maintaining fibers are frequently used to transmit polarized light without changing its polarization in optical systems, but the high cost and coupling efficiency problems hinder their usage in large-scale light paths. Polarization controllers, which operate arbitrary polarization generation and conversion at the expense of utilizing at least two optical elements such as a half-wave plate and quarter-wave plate, are too bulky for some special applications. Meanwhile, they can only generate desired output polarization of light by transcendentally determining the input polarization, which means that the existing polarization controllers cannot respond in real time. Metasurfaces composed of subwavelength nanoscatterers offer fruitful functionalities to manipulate the amplitude, phase and polarization of light. Here, we propose and experimentally demonstrate a real-time polarization controller realized by combining a depolarizer and polarizer into one monolithic metasurface. Arbitrary polarization states can be transferred to the required polarization with no requirement to determine the incident polarization in advance. Through combining with ordinary optical fibers, the proposed metasurface may also replace polarization-maintaining fibers and optical fiber polarizers in some polarization-dependent applications. This versatile concept may settle the problems of arbitrary polarization conversion once and for all.

MoS2-based broadband and highly efficient solar absorbers.

In order to obtain broadband, highly efficient, wide-angle, and polarization-insensitive solar absorbers, we propose a universal configuration consisting of monolayer molybdenum disulfide (MoS2) and the metal-insulator-metal structure, which gives rise to significant absorption enhancement of the MoS2 layer. Light trapping structures with silver square-, circle-, and crossed-shaped resonators are investigated. The localized surface plasmon resonances among the silver resonators induce prominent interaction between the incident photon and MoS2 layer, contributing to efficient absorption of light energy. Simulation results show that the absorber made of square patches enables the best performance and realizes absorptance higher than 90% from 400 to 666 nm and an average absorptance greater than 91% in the range of 400-700 nm. The average light absorption within the MoS2 layer reaches 74% in the visible spectrum, which is one of the highest levels for the existing MoS2-based absorbers. Meanwhile, the polarization-independent designs exhibit good angle tolerance within 50° incidences. Such a universal structure can also obtain broadband and highly efficient absorption by using other transition metal dichalcogenides such as MoSe2, WS2, and WSe2, which indicates that the configuration has great applicability in solar energy absorption of 2D materials. The proposed solar absorbers with simple configuration and broadband absorption in wide incident angles have potential in applications such as solar cells, photovoltaic devices, and blackbody materials.

Superior Carrier Lifetimes Exceeding 6 µs in Polycrystalline Halide Perovskites.

Lead halide perovskite films have witnessed rapid progress in optoelectronic devices, whereas polycrystalline heterogeneities and serious native defects in films are still responsible for undesired recombination pathways, causing insufficient utilization of photon-generated charge carriers. Here, radiation-enhanced polycrystalline perovskite films with ultralong carrier lifetimes exceeding 6 µs and single-crystal-like electron-hole diffusion lengths of more than 5 µm are achieved. Prolongation of charge-carrier activities is attributed to the electronic structure regulation and the defect elimination at crystal boundaries in the perovskite with the introduction of phenylmethylammonium iodide. The introduced electron-rich anchor molecules around the host crystals prefer to fill the halide/organic vacancies at the boundaries, rather than form low-dimensional phases or be inserted into the original lattice. The weakening of the electron-phonon coupling and the excitonic features of the photogenerated carriers in the optimized films, which together contribute to the enhancement of carrier separation and transportation, are further confirmed. Finally the resultant perovskite films in fully operating solar cells with champion efficiency of 23.32% are validated and a minimum voltage deficit of 0.39 V is realized.

In-situ chemical vapor deposition to fabricate Cuprous oxide/copper sulfide core-shell flowers with boosted and stable wide-spectral region photocatalytic performance.

Cu2O is widely used in the visible-light photocatalytic field, but its photocatalytic activity and stability still need to be further enhanced. Thus, searching for an efficient method to inhibit photocorrosion of Cu2O and boost its photogenerated charge carriers' separation is very important and challenging. Herein, Cu2O@CuS core-shell hexapetalous flowers were synthesized by hydrothermal and in-situ chemical vapor deposition (CVD) strategy. The Cu2O hexapetalous flowers were firstly obtained through hydrothermal procedure, and then CuS in-situ grew on Cu2O to form core-shell structure by CVD, which effectively inhibited the photocorrosion of Cu2O. Meanwhile, Cu2O@CuS core-shell structure could extend their light absorption ranges from 200 to 1500 nm; promote the separation of electrons and holes in photocatalytic system. Thus, under the wide-spectral region, Cu2O@CuS exhibited excellent photocatalytic performance for the degradation of tetracycline at 91% with good cycling ability, resulting from the effective separation of photogenerated charges, more free radicals such as OH and O2-, increases of utilization rate of visible-light. These results indicate that in-situ CVD strategy is a feasible method to improve visible-light photocatalytic activity and stability of Cu2O.

Interfacial engineering by creating Cu-based ternary heterostructures on C3N4 tubes towards enhanced photocatalytic oxidative coupling of benzylamines.

Benzylamine coupling is a very important reaction for the synthesis of imine but still faces many challenges. Herein, we present a highly effective strategy towards the coupling reaction by using environmentally friendly catalysts. These catalysts are composed of Cu/Cu2O/Cu3N heterostructures supported by C3N4 tubes and the composites were synthesized by one-step hydrothermal treatment followed by calcination. Cu2O, Cu3N, and C3N4 all are responsive to visible light and the heterojunction formed can greatly enhance the charge separation. When used as photocatalysts for oxidative self-coupling of benzylamine at a low temperature of 323 K in air, Cu/Cu2O/Cu3N/C3N4 was able to give conversion and selectivity values of up to 99% and 98%, respectively. The high efficiency of the catalysts is attributable to their ability to generate large quantities of free radicals (such as ·OH and ·O2 -) under visible-light irradiation.

Graphene-Based Spatial Light Modulator Using Metal Hot Spots.

Here, we report a graphene-based electric field enhancement structure achieved by several adjacent metal nanoribbons which form the hot spots of the electric field and thus promote the absorption of the single layered graphene below the hot spots. Based on the tunability of the graphene's Fermi level, the absorption rate can be modulated from near 100% to 35% under low electrostatic gating, leading to a 20 dB modulation depth of reflectance. Compared with the existing near infrared spatial light modulators such as optical cavities integrated with graphene and other structures utilizing patterned or highly doped graphene, our design has the advantages of strong optical field enhancement, low power dissipation and high modulation depth. The proposed electro-optic modulator has a promising potential for developing optical communication and exploiting big data interaction systems.

In-situ Platinum Plasmon Resonance Effect Prompt Titanium Dioxide Nanocube Photocatalytic Hydrogen Evolution.

Herein, Pt-decorated TiO2 nanocube hierarchy structure (Pt-TNCB) was fabricated by a facile solvothermal synthesis and in-situ photodeposition strategy. The Pt-TNCB exhibits an excellent solar-driven photocatalytic hydrogen evolution rate (337.84 µmol h-1 ), which is about 37 times higher than that of TNCB (9.19 µmol h-1 ). Interestingly, its photocatalytic property is still superior to TNCB with post modification Pt (1 wt %) (208.11 µmol h-1 ). The introduction of Pt efficiently extends the photoresponse of the composite material from UV to visible light region, simultaneously boosting their solar-driven photocatalytic performance, which attribute to the porous structure, the sub size TNCB, the SPR effect of Pt NPs and strong interaction of two components. In fact, Pt NPs can enhance collective oscillations on delocalized electrons, which is conducive to capture electrons and hinder the recombination of photogenerated electron-hole pairs, leading to the longer lifetime of photogenerated charges. The fabrication of Pt-TNCB photocatalyst with SPR effect may provide a promising method to improve visible-light photocatalytic activities for traditional photocatalysts.

[Clinical observation on deep-oblique acupuncture with long needle at Guanyuan (CV 4) for urinary retention].

OBJECTIVE: To observe differences of clinical therapeutic effects between deep-oblique acupuncture with long needle and regular perpendicular acupuncture at Guanyuan (CV 4) for urinary retention to explore standard acupuncture method in clinic. METHODS: One hundred and thirty-two cases of urinary retention were randomly divided into an observation group (78 cases) and a control group (54 cases). Needles with 75 mm in length were deeply and obliquely inserted into Guanyuan (CV 4) in the observation group while needles with 40 mm in length were perpendicularly inserted. Clinical therapeutic effects in two groups were observed. RESULTS: After treatment the total effective rate was 80.8% (63/78) in the observation group and 57.4% (31/54) in the control group, which had significant difference between two groups (P<0.05). The curative effect of postpartum retention of urine was obviously superior to that of postoperative and prostate-induced urinary retention in the ebservation group, and the effect of urinary retention due to different etiology in the observation was also superior to that in the control group in the ebservation group [in the observation group total effective rate was 88.6% (47/53) in postpartum retention of urine, 50.0% (3/6) in prostate-induced urinary retention and 68.4% (13/19) in orthopedic postoperative retention of urine while in the control group total effective rate was 69.4% (25/36) in postpartum retention of urine, 20.0% (1/5) in prostate-induced urinary retention and 38.5% (5/13) in orthopedic postoperative retention of urine)]. CONCLUSION: The deep-oblique acupuncture with long needle at Guanyuan (CV 4) has significant curative effect on urinary retention in clinic, especially for patients with postpartum urinary retention, which could be taken as standard acupuncture method.

Design and analysis of lumped resistor loaded metamaterial absorber with transmission band.

A new type of multi-layer metamaterial (MM) absorber is represented in this paper, which behave as a dielectric slab in transmission band and act as an absorber in another lower band. The equivalent circuit model of each layer in this MM absorber has been established. The transmission line (TL) model is introduced to analysis the mechanism of electromagnetic wave traveling through this MM absorber. Both theoretical and experimental results indicate this MM absorber has a transmission band at 21GHz and an absorptive band from 5GHz to 13GHz. A good match of TL model results and measurement results verified the validity of TL model in analyzing and optimizing the performances of this kind of absorber.

The Bragg gap vanishing phenomena in one-dimensional photonic crystals.

We theoretically deduce the Bragg gap vanishing conditions in one-dimensional photonic crystals and experimentally demonstrate the m=0 band-gap vanishing phenomena at microwave frequencies. In the case of mismatched impedance, the Bragg gap will vanish as long as the discrete modes appear in photonic crystals containing dispersive materials, while for the matched impedance cases, Bragg gaps will always disappear. The experimental results and the simulations agree extremely well with the theoretical expectation.

Invisible cloak design with controlled constitutive parameters and arbitrary shaped boundaries through Helmholtz's equation.

An approach to design an invisible cloak with controlled constitutive parameters and arbitrary shaped boundaries is presented. Helmholtz's equation is adopted to establish a mapping between original and transformed coordinates inside the cloak. Then the constitutive parameters are obtained by the established mapping. The analytical solution of a regular cloak and the numerical solution of an irregular cloak both verify that that our method will guide electromagnetic wave efficiently and control the constitutive parameters of the cloak conveniently. It has great significance in realizing a cloak practically.