Ultra-short Distance Research Articles

Relay electrocatalysis with bimetallic sites for highly efficient oxidation in multiple cascade reaction

The majority of electrocatalytic conversions of biomass-based molecules involve multiple steps utilizing the cascade reactions. As a result, maintaining the consecutive rate of each independent step is vital to improving the efficiency of the reaction. Whereas the single active species cannot entirely satisfy the demand of synchronous rates. Even with the use of bimetallic catalysts, the focus is still on facilitating the rate of the controlling step in the whole reaction. In this study, the NiCo-metal–organic framework (MOF) with diatomic sites was designed for the relay electrocatalytic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-furandicarboxylic acid (FDCA). The prepared Ni2Co1-MOF catalyst exhibited 97.3 % FDCA yield, and 90 % faradaic efficiency, and an excellent stability. Incorporating favorable catalytic activities of Ni and Co facilitates the alcohol-to-aldehyde and aldehyde-to-carboxylic acid conversions, respectively, verifying the relay effect with lower energy demand (1.35 V vs. RHE). Moreover, the ultrashort distance between two sites results in the faster diffusion of intermediates, further accelerating the reaction. The industrial simulation experiment using a pilot reaction equipment demonstrates the satisfied demands for industrial applications. This relay electrocatalysis path provides new insight into the rational design of catalysts for facilitating the electrorefining process with muti-step reactions.

Trajectory plan for an ultra-short distance on-orbit service based on the Gaussian pseudo-spectral method

Considering the ultra-short distance approaching plan of on-orbit service, the trajectory plan strategy based on the Gaussian pseudo-spectral method is researched. Given the target spinning, safety, fuel and maneuver factors, a model which contains a secure area as well as a prohibited area is built. Furthermore, the method to plan a safe on-orbit service trajectory and the solution based on the Gaussian pseudo-spectral method are also presented. Finally, simulations are performed to prove the validity of the plan, and analyze the influence of optimal function and maneuver time. The results demonstrate that the planned trajectory is capable of avoiding the prohibited area and finding the best trajectory in terms of the relative distance, fuel cost and maneuver time respectively.

Design and experiment of high-resolution detection imaging system with ultra-thin and ultra-short object-image distance

Design and experiment of high-resolution detection imaging system with ultra-thin and ultra-short object-image distance

Effect of HVOF–sprayed nanostructured WC–10Co–4Cr coating on sliding wear and tensile–tensile fatigue properties of TC6 titanium alloy

Aerospace equipment has been placing greater demands on the wear resistance and fatigue strength of titanium alloys. In light of this, the research objective was to prepare a WC-10Co-4Cr coating with better performance through the utilization of the ultra-short distance high-speed oxygen fuel (HVOF) spraying process. Then the microstructure, microhardness, sliding wear, and fatigue performance of TC6 alloy reinforced with WC–10Co–4Cr coating were further explored and analyzed. The ultra–short distance HVOF spraying process was employed to suppress decarburization, resulting in a minimal amount of W2C phase in the coating. The WC–10Co–4Cr coating exhibited excellent surface characteristics, displaying minimal microcracks and a low porosity rate of 0.15 ± 0.08%. The interface between the coating and the substrate was sharp and clean, while the TC6 alloy retained its dual structural characteristics without any microstructural changes. The microhardness of the WC–10Co–4Cr coating exhibited a remarkable value of 1172.64 HV0.025, which is 3.2 times greater than that of the substrate. The coating exhibited a noteworthy decrease in wear rate, wear depth, and wear area, indicating superior wear resistance. Additionally, a thorough examination was conducted to uncover the underlying wear mechanism of the coating under different loads. The WC-10Co-4Cr coating, which was developed through this study, shows a minimal influence on the fatigue strength of the original base material. Furthermore, a comprehensive analysis was conducted to elucidate the factors contributing to the significant fatigue life of the WC–10Co–4Cr coating.

Designed 2D/2D/2D Bi2WO6/Ti3C2/SnNb2O6 Z-scheme heterojunction via interfacial chemical bond with enhanced photocatalytic activity

2D/2D/2D materials are widely used in photocatalysis owing to the advantages of high specific surface area, large contact interface, numerous charge transfer channels and ultrashort charge transfer distance. In this work, 2D/2D/2D Bi2WO6/Ti3C2/SnNb2O6 catalysts were successfully constructed via an anaerobic hydrothermal method. Due to ultrathin 2D Ti3C2 MXene served as an electron mediator and combined with 2D SnNb2O6 and 2D Bi2WO6 by Ti−O−Sn interface bond or Ti–O–Bi interface bond to form Z-scheme heterojunction, which could afford charge transfer channels and increase reactive sites. As a result, the Bi2WO6/Ti3C2/SnNb2O6 composites significantly improved the photodegradation efficiency of tetracycline hydrochloride due to the high redox ability, and its degradation rate in 90 min was 10.22 times that of SnNb2O6. This work provides an effective method to construct 2D/2D/2D Z-scheme heterojunction by tight chemical bond.

A protein-targeted photosensitizer for highly efficient cancer therapy

Photodynamic therapy typically employs photo-triggered photosensitizers to generate reactive oxygen species to destroy cancer cells. However, the therapeutic effect of photodynamic therapy is often limited owing to the ultrashort diffusion distance of reactive oxygen species and easy efflux of photosensitizers. Herein, we design and synthesize a protein-targeted molecular photosensitizer for highly efficient photodynamic therapy. The designed photosensitizer can covalently bind with the sulfhydryl groups of intracellular proteins to achieve the protein targeting. Under irradiated with near infrared laser, the photosensitizer was locally activated, and the produced reactive oxygen species directly destroy intracellular bioactive proteins, causing cell dysfunction and ultimately inducing cell apoptosis. Significantly, the leakage of molecular photosensitizer is effectually avoided due to the protein targeting. In vivo experimental results indicated that the effect of treatment was efficiently enhanced with the protein-targeted strategy. This work can offer new insights for designing protein-based therapeutic drugs.

Boronic Acid-Decorated Multivariate Photosensitive Metal-Organic Frameworks for Combating Multi-Drug-Resistant Bacteria.

Metal-organic frameworks (MOFs) are promising photosensitized materials that have displayed great advantages in antibacterial application. However, their bactericidal activity is still limited by the ultrashort diffusion distance of biocidal reactive oxygen species (ROS). Herein, we integrate the bacterial-binding boronic acid ligand and photosensitized porphyrin into one single MOF, synergistically boosting antibiotic capability. The introduction of the boronic acid group with a closed physical gap makes multivariate MOFs more powerful for eradicating multi-drug-resistant (MDR) bacteria. The MOFs that are decorated with boronic acid possess antibacterial efficiencies (10-20 times) higher than those without the targeting ligand. Moreover, the MOFs exhibit excellent biocompatibility. They significantly decrease the inflammatory responses and accelerate the healing of chronic wounds infected with MDR bacteria (nearly 2 times faster). This work provides a strategy to develop multivariate MOFs that target bacteria, which will further inspire specific bacterial-binding therapy in the future.

A Nanohook-Equipped Bionanocatalyst for Localized Near-Infrared-Enhanced Catalytic Bacterial Disinfection.

Novel bionanocatalysts have opened a new era in fighting multidrug‐resistant (MDR) bacteria. They can kill bacteria by elevating the level of reactive oxygen species (ROS) in the presence of chemicals like H2O2. However, ROSs’ ultrashort diffusion distance limit their bactericidal activity. We present a nanohook‐equipped bionanocatalyst (Ni@Co‐NC) with bacterial binding ability that shows robust ROS‐generating capacity under physiological H2O2 levels. The Ni@Co‐NC's pH‐dependent performance confines its effects to the biofilm microenvironment, leaving healthy tissue unaffected. Furthermore, it can generate heat upon NIR laser irradiation, enhancing its catalytic performance while achieving heat ablation against bacteria. With the Ni@Co‐NC's synergistic effects, bacterial populations fall by >99.99 %. More surprisingly, the mature biofilm shows no recurrence after treatment with the Ni@Co‐NC, demonstrating its tremendous potential for treating MDR bacterial related infections.

A Nanohook‐Equipped Bionanocatalyst for Localized Near‐Infrared‐Enhanced Catalytic Bacterial Disinfection

AbstractNovel bionanocatalysts have opened a new era in fighting multidrug‐resistant (MDR) bacteria. They can kill bacteria by elevating the level of reactive oxygen species (ROS) in the presence of chemicals like H2O2. However, ROSs’ ultrashort diffusion distance limit their bactericidal activity. We present a nanohook‐equipped bionanocatalyst (Ni@Co‐NC) with bacterial binding ability that shows robust ROS‐generating capacity under physiological H2O2 levels. The Ni@Co‐NC's pH‐dependent performance confines its effects to the biofilm microenvironment, leaving healthy tissue unaffected. Furthermore, it can generate heat upon NIR laser irradiation, enhancing its catalytic performance while achieving heat ablation against bacteria. With the Ni@Co‐NC's synergistic effects, bacterial populations fall by >99.99 %. More surprisingly, the mature biofilm shows no recurrence after treatment with the Ni@Co‐NC, demonstrating its tremendous potential for treating MDR bacterial related infections.

Polarization and Holography Recording in Real‐ and k‐Space Based on Dielectric Metasurface

AbstractThe diverse design freedom and mechanisms of metasurfaces motivate the manipulation of polarization in an ultrashort distance with subwavelength resolution and make metasurfaces outperform conventional polarization optical elements. However, in order to enhance the information capability and encryption security of metasurface holograms, polarization manipulation together with multiplexing technologies are still highly desired. Here, a birefringent dielectric metasurface with the capability of encoding a grayscale image in real‐space based on Malus's law by utilizing the inhomogeneous polarization distribution and realizing the reconstruction of a vectorial holographic image in k‐space with the help of the phase profiles of different polarization components of output light is demonstrated. This novel functionality is realized by exploiting the manipulation of polarization and phase of output light simultaneously offered by the dielectric metasurface. The proposed method may enhance the information capability and security level of applications such as the anticounterfeiting and encryption.

Method for Measuring Ultra-Short Distances Using RADARs for Burden Profile Measurement at Blast Furnace

The operation of the furnace depends largely on the handling of gas distribution which in-turn is reliant on the burden surface profile. Measurement of burden profile has been a challenge because of the harsh conditions inside the furnace. Phased array radar will suffice this purpose with no moving parts; however, it imposes its own challenges. One of them is measurement of extremely short distances as the stockline in the blast furnace is just few meters away from the topmost part. Unlike conventional radar where the target is kilometre away the short distance measurement involves with time measure din nano seconds with pico-seconds resolution to achieve the desired accuracy. This paper implements a method for ultra-short distance measurement using radars for blast furnace application in steel plant.

A New Bamboo-Shaped Sensor for Curvature Measurement With Microstructured Fiber

In this letter, we propose a novel bamboo-shaped interference sensor based on multistage photonic-band gap microstructured fiber (PBG-MF) and single-mode fiber (SMF) to build the cascaded Fabry-Perot interferometer (FPI). Due to the honeycomb space inside the PBG-MF, a higher extinction ratio (ER) is obtained in the reflection spectrum of the interferometer, which is conducive to improving the detection limit (DL) and resolution of the sensor. The bending direction can be identified by the structure proposed in this letter. Maximum curvature sensitivity is 991 pm/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> in the convex direction. Maximum curvature sensitivity is -1118 pm/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> in the concave direction. The sensor has the advantages of small size, high sensitivity, and high package stability. It is particularly suitable for ultra-short distance curvature sensing, such as the joints of the human body.

General and Efficient Synthesis of Two-Dimensional Monolayer Mesoporous Materials with Diverse Framework Compositions.

Two-dimensional (2D) mesoporous materials have received substantial research interest due to their highly exposed active sites and unusual nanoconfinement effect. However, controllable and efficient synthesis of 2D mesoporous materials and investigation of their intrinsic properties have remained quite rare. Herein, a general and effective surface-limited cooperative assembly (SLCA) method enabled by leveling precursor solutions on KCl crystals via centrifugation is employed to conveniently synthesize two-dimensional (2D) monolayer mesoporous materials with different compositions. This novel strategy is performed in a manner similar to spin coating, not only enabling generation of ultrathin mesostructured composite film on KCl particles and recycling excessive precursor solution but also providing favorable solvent annealing environment for the film to form ordered mesostructures. Taking monolayer mesoporous Ce0.8Zr0.2O2 solid solutions as a sample, they display ultrathin nanosheet morphology with a thickness of ∼20 nm, highly open porous structure, and easily accessible active sites of surface superoxide species. Upon decoration of 2D mesoporous Ce0.8Zr0.2O2 nanosheets with Pt nanoparticles, the obtained catalyst exhibits superior catalytic activity and stability toward CO oxidation with a low onset temperature of 30 °C and a 100% conversion temperature of 95 °C, which are 35-70 °C lower than those for their counterpart materials, namely, three-dimensional (3D) mesoporous Pt/Ce0.8Zr0.2O2. Moreover, their TOFPt value is ∼11.3 times higher than that of 3D mesoporous Pt/Ce0.8Zr0.2O2. Characterizations based on various techniques indicate that such an outstanding catalytic performance is due to the ultrashort distance (20 nm) of mass diffusion, highly exposed active sites, rich surface-chemisorbed oxygen, and the synergistic effect between the Ce0.8Zr0.2O2 matrix and Pt species.

Mechanically Asymmetrical Triboelectric Nanogenerator for Self‐Powered Monitoring of In Vivo Microscale Weak Movement

AbstractAlthough much effort has been put in the studies of weak in vivo microscale movements due to its importance, the real‐time, long‐time, and accurate monitoring is still a great challenge because of the complexity of the in vivo environment. Here, a new type of mechanically asymmetrical triboelectric nanogenerator with ultrashort working distance and high anti‐interference ability is developed to accurately and real‐timely monitor the microscopically weak movement of intestinal motility at low frequencies even around 0.3 Hz. The intestinal status after the glucose absorption, and physiological states in different times also have been monitored successfully in the complex in vivo environment with many kinds of interference and noises. This work gives a new self‐powered, long‐time and in vivo technical way for the real‐timely gastrointestinal motility monitoring, and contributes to the detection of every kind of gentle movements in various complex bio‐systems.

Miniaturized high-performance metallic 1T-Phase MoS2 micro-supercapacitors fabricated by temporally shaped femtosecond pulses

The recent development of wearable and portable microelectronic devices requires energy storage devices to be miniaturized; micro-supercapacitors (MSCs), as one of the most outstanding candidates, have great potential in future electronic devices. However, in the miniaturization of MSCs, the maintenance of electrochemical performance remains a key challenge. Herein, this study proposes a simple, one-step, mask-free and high-resolution fabrication method for high-performance 1T MoS2 MSCs in atmosphere. The method involves the direct writing of restacked 1T MoS2 films by a temporally shaped femtosecond laser. Specifically, femtosecond laser pulses are temporally shaped to control the transient electron temperature and material absorption for achieving high-resolution fabrication. Excellent electrode material properties and ultrashort ion transfer distance enable the MSCs to exhibit optimal performances with an ultrahigh power density (14 kW cm−3), ultrahigh energy density (15.6 mWh cm−3) and large areal capacitance (36 mF cm−2). Notably, such miniaturized MSCs in a 100 × 100 μm2 area own superior frequency responses (1221 Hz) and time constant (0.82 ms), which are suitable for AC line filters and other high-power demanded electronic devices. This method successfully solves the problem of maintaining performance in the miniaturization of MSCs, allowing next-generation microelectronic devices to be developed.

Compact freeform primary lens design based on extended Lambertian sources for liquid crystal display direct-backlight applications

A concept for a freeform primary lens system (FPLS) is proposed for designing freeform optics in the direct-backlight system of liquid crystal displays. This FPLS has a super small ratio of height of the optics system h to LED source with diameter D by avoiding the use of traditional secondary optics for LED illumination applications. The FPLS is first designed based on energy conservation principles and ray mapping techniques, and improved through feedback optimization algorithms. Both simulation data and experimental data are employed successively to improve the illumination uniformity on the target plane. Meanwhile, the divergence angle of the FPLS is further improved to achieve a more uniform irradiance distribution pattern of the LED luminaire array on the target plane with an ultrashort projection distance between source and target. We demonstrate the concept by designing and manufacturing an FPLS; the experimental data show that, with h / D = 0.98 of the optical system, the relative standard deviation of the target area reaches 0.22 within the divergence angle of 120 deg.

The art of the state

Quantum field theory (QFT) on curved spacetimes lacks an obvious distinguished vacuum state. We review a recent no-go theorem that establishes the impossibility of finding a preferred state in each globally hyperbolic spacetime, subject to certain natural conditions. The result applies in particular to the free scalar field, but the proof is model-independent and therefore of wider applicability. In addition, we critically examine the recently proposed “SJ states”, that are determined by the spacetime geometry alone, but which fail to be Hadamard in general. We describe a modified construction that can yield an infinite family of Hadamard states, and also explain recent results that motivate the Hadamard condition without direct reference to ultra-high energies or ultra-short distance structure.

Zoom projection lens design for small throw ratio and large field of view

In order to meet the requirements of large screen projection displays, we propose an ultra-thin zoom projection lens with a small throw ratio (TR), ultra-short throw distance and large field-of-view (FOV) using a digital micromirror device as a spatial modulator. A refractive–reflective system is developed to correct the distortion and shorten the projection distance. The image size (diagonal, 16:9 aspect ratio) of the projector is 80–120 in. (2.032–3.048 m) with a TR of 0.22, TV distortion < 0.6%, root mean square (RMS) spot size < 1.1 mm, relative illumination > 85% and modulation transfer function > 0.4 at 0.55 lp/mm for all fields and zoom conditions. When the tolerance error is considered, the RMS value is less than 1.3 mm for all fields and zoom conditions. Finally, the projection lens is fabricated and tested according to the designed model.

Combining covalent bonding and electrostatic attraction to achieve highly viable species with ultrashort beryllium-beryllium distances: a computational design.

Though ultrashort metal-metal distances (USMMD, dM-M < 1.900 Å) were primarily realized between transition metals, USMMDs between main group metal atoms such as beryllium atoms have also been designed previously using two strategies: (1) formation of multiple bonding orbitals or (2) having favourable electrostatic attraction. We recently turned our attention to the reported species IH → Be2H2 ← IH (where IH denotes imidazol-2-ylidene) because the orbital energy level of its π-type HOMO is noted to be very high, which may result in intrinsic instability. In the present study, we combined the abovementioned strategies to solve the high orbital energy level problem without losing the ultrashort Be-Be distances. It was found that breaking of such π-type HOMO by addition of a -CH2- group onto the bridging position of two beryllium atoms led to the formation of IH → Be2H2CH2 ← IH species, which not only possesses an ultrashort Be-Be distance in the -Be2H2CH2- moiety, but also has a relatively low HOMO energy level. Replacing the IH ligands with NH3 and PH3 resulted in the formation of NH3 → Be2H2CH2 ← NH3 and PH3 → Be2H2CH2 ← PH3 species with similar features. The electronic structure analyses suggest that the ultrashort Be-Be distances in these species are achieved by the combined effects of the formation of two Be-H-Be 3c-2e bonds and having favourable Coulombic attractions between the carbon atom of the -CH2- group and two beryllium atoms. Remarkably, when the IH, NH3, and PH3 ligands were replaced by large ligands with bulky groups, such as 1,3-bis(2,6-diisopropyl phenyl)imidazol-2-ylidene (IDip), triphenylamine (NPh3), and triphenylphoshpine (PPh3), respectively, the resultant species IDip → Be2H2CH2 ← IDip, NPh3 → Be2H2CH2 ← NPh3, and PPh3 → Be2H2CH2 ← PPh3 exhibit good steric protection around the -Be2H2CH2- core. These species are thus examples for the experimental realization of species with ultrashort metal-metal distances between main group metals.

高輝度・超短焦点レーザ光源プロジェクタの開発(映像情報機器および一般)

高輝度・超短焦点レーザ光源プロジェクタの開発(映像情報機器および一般)