The effect of Er3+ concentration on the kinetics of multiband upconversion in NaYF4:Yb/Er microcrystals

In Yb-Er co-doped upconversion (UC) nanomaterials, upconversion luminescence (UCL) can be modulated to generate multiband UCL emissions by changing the concentration of activator Er3+. Nonetheless, the effect of the Er3+ concentrations on the kinetics of these emissions is still unknown. We here study the single β-NaYF4:Yb3+/Er3+ microcrystal (MC) doped with different Er3+ concentrations by nanosecond time-resolved spectroscopy. Interestingly, different Er3+ doping concentrations exhibit different UCL emission bands and UCL response rates. At low Er3+ doping concentrations (1 mol%), multiband emission in β-NaYF4:Yb3+/Er3+ (20/1 mol%) MCs could not be observed and the response rate of UCL was slow (5–10 μs) in β-NaYF4:Yb3+/Er3+. Increasing the Er3+ doping concentration to 10 mol% can shorten the distance between Yb3+ ions and Er3+ ions, which promotes the energy transfer between them. β-NaYF4:Yb3+/Er3+ (20/10 mol%) can achieve obvious multiband UCL and a quick response rate (0.3 µs). However, a further increase in the Er doping concentration (80 mol%) makes MCs limited by the CR process and cannot achieve the four-photon UC process (4F5/2 → 2K13/2 and 2H9/2 → 2D5/2). Therefore, the result shows that changing the Er3+ doping concentration could control the energy flow between the different energy levels in Er3+, which could affect the response time and UCL emission of the Yb/Er doped rare earth materials. Our work can facilitate the development of fast-response optoelectronics, optical-sensing, and display industries

Progress and application of intelligent fluid supply technology in working face

Intelligent fluid supply technology in working face is one of the core technologies of intelligent mining. In order to solve the requirements of high data transmission rate, high transmission stability and high data processing ability in the intelligent work face, a centralized-distributed emulsion station control system based on the 100 megabit industrial Ethernet was developed, fault prediction and health management technology and intelligent on-demand liquid supply control technology were studied, which improves intelligent control function, and the development demand of the working media quality assurance technology of the work face hydraulic system was analyzed, and key technologies such as underground integrated reverse osmosis (RO) water treatment technology, high-efficiency multi-stage filtration technology, fully automated emulsion automatic ratio and concentration correction technology and other key technologies were innovated. In order to overcome the key technical problems such as high-strength corrosion-resistant materials, reliability technology of the suction and discharge valves under pure water medium and pure water resistivity assurance technology, the development of intelligent fluid supply system under pure water condition has promoted the development of green mining technology. The core technical problems such as unattended intelligent safety control technology, timely and rapid liquid supply and return relay technology, integrated multi-parameter safety monitoring of long-distance supply pipeline technology with integrated multi parameter monitoring have been overcome, and the problems of remote safe and efficient liquid supply in mines with complex geological conditions have been solved.. This achievement has been popularized and applied in the fully mechanized mining and fully mechanized caving working faces of thin and medium thick coal seams in Shendong Mining Area of National Energy Group, Shanxi Mining Area of China Coal Energy Group, and Yankuang Mining Area of Shandong Energy Group, meeting the demand for liquid supply technology and equipment in the development of intelligent mining at this stage

Studies of Electroless Copper Plating on Poplar Veneer

Copper coating was deposited on poplar veneer using different relative concentrations of plating solution. The coating structure, thickness, crystal structure, surface resistivity, contact angle, surface free energy, and electromagnetic shielding effectiveness were investigated. The surface morphology and thickness were observed using scanning electron microscopy, and the crystal structure was analyzed using X-ray diffraction. Increasing the relative concentration of plating solution resulted in a uniform and dense coating structure, and the thickness notably increased. In addition, the lateral direction resistivity was two times greater than the longitudinal direction resistivity, and the surface wettability changed from hydrophilic to hydrophobic, which led to a decline in surface free energy. Electromagnetic shielding effectiveness reached 62 dB in the frequency range of 10 kHz to 1.5 GHz. The electroless plating copper veneer was optimal when the solution contained 80 g/L of CuSO4·5H2O, 20 g/L of C4O6H4KNa, 40 g/L of EDTA-2Na, and 40 mL/L of HCHO 40 mL/L

Ballistic impact behavior of thin nickel-base alloy plates at different temperatures

To study the aeroengine containment capability in high temperature, experiments and numerical simulations of the spherical nosed projectile impacting thin plate under 25 ℃ and 600 ℃ were performed. Experiments were conducted by using a gas gun. Target plates were impacted by bullets with different initial velocities. The effect of temperature and initial velocity on the deformation, failure pattern and energy absorption of the plate were analyzed. The results show that at higher temperature, the deformation of the target plates is greater, the energy absorbed by the target plates is smaller and the critical ballistic velocities are smaller . The petal deformation of the target plate caused by bending is more obvious under 600 ℃. Numerical simulations of the impact were conducted by using an explicit dynamics FE code (LS-DYNA). The Johnson-Cook material model was used to carry out the analysis. The Johnson-Cook material model parameters were obtained by the separated Hopkinson pressure bar (SHPB) experiment at high temperature. The results obtained from the numerical simulations were compared with those from the experiments. Good correlation is found between experiments and numerical simulations

Triacylglycerol, fatty acid, and phytochemical profiles in a new red sorghum variety (Ji Liang No. 1) and its antioxidant and anti‐inflammatory properties

In this study, a new red sorghum variety (Ji Liang No. 1) was investigated for its triacylglycerol (TAG) and fatty acid profiles, carotenoid and tocopherol compositions, total phenolic, total flavonoid and phenolic acid contents, and antioxidant and anti‐inflammatory properties. A total of 17 TAGs were identified in the red sorghum oil. Linoleic and oleic acids were the primary fatty acids, contributing more than 80% of the total fatty acids. β‐Carotene was the primary carotenoid at a level of 26.14 μg/g. α‐, γ‐, and δ‐tocopherols were at levels of 0.19, 4.08, and 0.10 μg/g, respectively. Moreover, acetone–water (60:40, v/v) extract of the red sorghum exhibited the greatest total phenolic content of 2.77 mg GAE/g and total flavonoid content of 5.44 mg RE/g. The extract had scavenging capacities against DPPH, ABTS+, and peroxyl radicals and suppressed LPS stimulated IL‐1β, IL‐6, and COX‐2 mRNA expressions in a dose‐dependent manner. Ferulic, p‐coumaric, isoferulic, and p‐hydroxybenzoic acids were found in the red sorghum, with ferulic acid as the predominant phenolic acid and mostly in an insoluble bound form. These data indicated a potential utilization of the red sorghum in health‐promoting functional food or supplemental products

Triacylglycerol, fatty acid, and phytochemical profiles in a new red sorghum variety (Ji Liang No. 1) and its antioxidant and anti‐inflammatory properties

In this study, a new red sorghum variety (Ji Liang No. 1) was investigated for its triacylglycerol (TAG) and fatty acid profiles, carotenoid and tocopherol compositions, total phenolic, total flavonoid and phenolic acid contents, and antioxidant and anti‐inflammatory properties. A total of 17 TAGs were identified in the red sorghum oil. Linoleic and oleic acids were the primary fatty acids, contributing more than 80% of the total fatty acids. β‐Carotene was the primary carotenoid at a level of 26.14 μg/g. α‐, γ‐, and δ‐tocopherols were at levels of 0.19, 4.08, and 0.10 μg/g, respectively. Moreover, acetone–water (60:40, v/v) extract of the red sorghum exhibited the greatest total phenolic content of 2.77 mg GAE/g and total flavonoid content of 5.44 mg RE/g. The extract had scavenging capacities against DPPH, ABTS+, and peroxyl radicals and suppressed LPS stimulated IL‐1β, IL‐6, and COX‐2 mRNA expressions in a dose‐dependent manner. Ferulic, p‐coumaric, isoferulic, and p‐hydroxybenzoic acids were found in the red sorghum, with ferulic acid as the predominant phenolic acid and mostly in an insoluble bound form. These data indicated a potential utilization of the red sorghum in health‐promoting functional food or supplemental products