Ultrasound Ranging with Selective Zone

The technology of ultrasonic measurement has been widely applied in many fields in recent years. It has already been researched for almost 40 years and its application in both residential use and military are mature and well-developed. One of the advanced uses is for reversing a car and it is based on sending sound waves through a specific medium and observing the returning echoes to measure the distance from the device to the obstacle. In this report, a simple ultrasonic distance measurement system will be introduced including the design of hardware and software, the simulating results and the final product. This system was built to be cheaper, requires less power and delivers better performance.

Mutual Self‑Regulation of d‑Electrons of Single Atoms and Adjacent Nanoparticles for Bifunctional Oxygen Electrocatalysis and Rechargeable Zinc‑Air Batteries

Rechargeable zinc-air batteries(ZABs)are a promising energy conversion device,which rely critically on electrocatalysts to accelerate their rate-determining reactions such as oxygen reduction(ORR)and oxygen evolution reactions(OER).Herein,we fabricate a range of bifunctional M-N-C(metal-nitrogen-carbon)catalysts containing M-Nx coordination sites and M/MxC nanoparticles(M=Co,Fe,and Cu)using a new class ofγ-cyclodextrin(CD)based metal-organic framework as the precursor.With the two types of active sites interacting with each other in the catalysts,the obtained Fe@C-FeNC and Co@C-CoNC display superior alkaline ORR activity in terms of low half-wave(E1/2)potential(~0.917 and 0.906 V,respectively),which are higher than Cu@C-CuNC(~0.829 V)and the commercial Pt/C(~0.861 V).As a bifunctional electrocatalyst,the Co@C-CoNC exhibits the best performance,showing a bifunctional ORR/OER overpotential(ΔE)of~0.732 V,which is much lower than that of Fe@C-FeNC(~0.831 V)and Cu@C-CuNC(~1.411 V),as well as most of the robust bifunctional electrocatalysts reported to date.Synchrotron X-ray absorption spectroscopy and density functional theory simulations reveal that the strong electronic correlation between metallic Co nanoparticles and the atomic Co-N4 sites in the Co@C-CoNC catalyst can increase the d-electron density near the Fermi level and thus effectively optimize the adsorption/desorption of intermediates in ORR/OER,resulting in an enhanced bifunctional electrocatalytic performance.The Co@C-CoNC-based rechargeable ZAB exhibited a maximum power density of 162.80 mW cm^(−2) at 270.30 mA cm^(−2),higher than the combination of commercial Pt/C+RuO2(~158.90 mW cm^(−2) at 265.80 mA cm^(−2))catalysts.During the galvanostatic discharge at 10 mA cm^(−2),the ZAB delivered an almost stable discharge voltage of 1.2 V for~140 h,signifying the virtue of excellent bifunctional ORR/OER electrocatalytic activity.

Research and Application of Advanced Detection of Water Hazards in Coal Mine Bore-Hole

For many years, the “short excavation and short exploration” excavation mode has been mainly used in the underground tunnel excavation of coal mines, which is difficult to meet the needs of rapid tunnel excavation. For this reason, CCTEG Xi’an Research Institute has innovatively proposed a new working mode of “long excavation and long exploration” using directional long drilling and borehole geophysical exploration. This method utilizes directional long boreholes that have already been constructed, and uses transient electromagnetic technology in the borehole to detect the radial range of 30 meters and the depth exceeding 1000 meters of the borehole, ultimately forming a three-dimensional imaging of the entire spatial geological anomaly body, providing reliable technical support for the safety and long-term excavation of the tunnel. This paper introduces the application which is a long-distance advanced detection of 1026 m. .

Coupling of piezocatalysis and photocatalysis for efficient degradation of methylene blue by Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3) nanotubes

Photocatalytic degradation of organic pollutants is of great significance for wastewater remediation but is still hindered by the poor catalytic efficiency of the catalysts.Herein,we report a strategy to simultaneously introduce piezocatalysis and to enhance the intrinsic photocatalysis in a single catalyst,which improved the performance for catalytic degradation of methylene blue(MB)significantly.Specifically,piezoelectric BiFeO_(3)(BFO)nanotube doped with different contents of Gd and La(Bi_(0.9)(GdxLa_(1−x))0.1FeO_(3))were produced by electrospinning.The doping led to a higher concentration of surface oxygen vacancy(OV)in Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3),which effectively increased the piezoelectric field due to the deformation of BFO,and suppressed the recombination of photon-generated electron–hole pairs.The Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3)nanotube showed excellent catalytic performance under simultaneous light irradiation and ultrasonic excitation,giving an extraordinary 95%degradation of MB within 90 min.These findings suggest that the piezoelectric effect combined with defect engineering can enhance the catalytic performance of Bi_(0.9)Gd_(0.07)La_(0.03)FeO_(3)nanotube.This could potentially be extended to other catalytic systems for high-performance pollutant treatment.

In-situ encapsulation ofα-Fe_(2)O_(3) nanoparticles into ZnFe_(2)O_(4) micro-sized capsules as high-performance lithium-ion battery anodes

Transition metal oxides as anode materials for high-performance lithium-ion batteries suffer from severe capacity decay,originating primarily from particle pulverization upon volume expansion/shrinkage and the intrinsically sluggish electron/ion transport.Herein,in-situ encapsulation ofα-Fe_(2)O_(3) nanoparticles into micro-sized ZnFe_(2)O_(4) capsules is facilely fulfilled through a co-precipitation process and followed by heat-treatment at optimal calcination temperature.The porous ZnFe_(2)O_(4) scaffold affords a synergistic confinement effect to suppress the grain growth ofα-Fe2 O3 nanocrystals during the calcination process and to accommodate the stress generated by volume expansion during the charge/discharge process,leading to an enhanced interfacial conductivity and inhibit electrode pulverization and mechanical failure in the active material.With these merits,the preparedα-Fe_(2)O_(3)/Fe_(2)O_(4) composite delivers prolonged cycling stability and improved rate capability with a higher specific capacity than soleα-Fe_(2)O_(3) and Fe_(2)O_(4).The discharge capacity is retained at 700 mAh g-1 after 500 cycles at 200 mA g^(-1) and 940 mAh g^(-1) after 50 cycles at 100 m A g^(-1).This work provides a new perspective in designing transition metal oxides for advanced lithium-ion batteries with superior electrochemical properties.

Supramolecular-mediated ball-in-ball porous carbon nanospheres for ultrafast energy storage

Hierarchical porous carbons are the most viable electrode material for supercapacitors because of their balanced capacitive performance and chemical stability.Their pore connectivity plays a pivotal role in electrolyte transport,which is quantified by a new parameter,defined in this work as the longest possible pore separation(LPPS).Herein,we report hierarchical porous carbon nanospheres(HPC-NS)with a unique ball-in-ball structure,which is achieved by the pyrolysis of a supramolecular complex ofγ-cyclodextrin(γ-CD)/PEO-PPO-PEO(F127).This approach differs from the conventional softtemplating method in that,apart from the assembly of the monomicelles that leads to the host nanospheres(approximately 300 nm),theγ-CD-containing monomicelles themselves are converted to small porous carbon nanospheres(<10 nm),which results in an ultralow LPPS of 10 nm,representing the bestknown pore connectivity of the HPC family.The HPC-NS delivers a high specific capacitance(405 F g^(-1)at 1 A g^(-1)and 71%capacitance retention at 200 A g^(-1)),wide voltage window(up to 1.6 V),and simultaneously high energy and power densities(24.3 Wh kg^(-1)at a power density of 151 W kg^(-1)and 9 Wh kg^(-1)at 105 W kg^(-1))in aqueous electrolytes.This new strategy boosts the development of porous carbon electrodes for aqueous supercapacitors with simultaneously high power and energy densities.