Geometric effects on mixing performance in a novel passive micromixer with trapezoidal-zigzag channels

A novel passive micromixer, called a trapezoidal-zigzag micromixer (TZM), is reported. A TZM is composed of trapezoidal channels in a zigzag and split–recombine arrangement that enables multiple mixing mechanisms, including splitting–recombining, twisting, transversal flows, vortices, and chaotic advection. The effects of geometric parameters of the TZM on mixing performance are systematically investigated by the Taguchi method and numerical simulations in COMSOL Multiphysics. The number of mixing units, the slope angle of the trapezoidal channel, the height of the constriction element, and the width ratio between the middle-trapezoidal channel and the side-trapezoidal channel are the four parameters under study. The mixing performance of the TZM is investigated at three different Reynolds number (Re) values of 0.5, 5, and 50. The results showed that a TZM with six mixing units, a trapezoidal slope angle of 75°, a constricting height of 100 µm, and a width ratio of 0.5 has the highest mixing efficiency. This optimal TZM has a mixing efficiency greater than 85% for Re values from 0.1 to 80. In particular, for Re  ≤  0.9 and Re  ≥  20, the mixing efficiency of the optimal TZM is greater than 90%. The proposed TZM has a higher mixing efficiency and a smaller footprint than previously reported micromixers

Fabrication of 3D Air-core MEMS Inductors for High Frequency Power Electronic Applications

AbstractWe report a fabrication technology for 3D air-core inductors for small footprint and very-high-frequency power conversions. Our process is scalable and highly generic for fabricating inductors with a wide range of geometries and core shapes. We demonstrate spiral, solenoid, and toroidal inductors, a toroidal transformer and inductor with advanced geometries that cannot be produced by wire winding technology. The inductors are embedded in a silicon substrate and consist of through-silicon vias and suspended windings. The inductors fabricated with 20 and 25 turns and 280-350 μm heights on 4-16 mm2 footprints have an inductance from 34.2 to 44.6 nH and a quality factor from 10 to 13 at frequencies ranging from 30 to 72 MHz. The air-core inductors show threefold lower parasitic capacitance and up to a 140% higher-quality factor and a 230% higher-operation frequency than silicon-core inductors. A 33 MHz boost converter mounted with an air-core toroidal inductor achieves an efficiency of 68.2%, which is better than converters mounted with a Si-core inductor (64.1%). Our inductors show good thermal cycling stability, and they are mechanically stable after vibration and 2-m-drop tests.</jats:p

ẢNH HƯỞNG CỦA LIỀU LƯỢNG LƯU HUỲNH ĐẾN HAI GIỐNG LẠC L14 VÀ SVL1 TẠI TỈNH QUẢNG BÌNH

Tóm tắt: Thí nghiệm gồm có 4 liều lượng lưu huỳnh trên hai giống lạc L14 và SVL1, bố trí theo kiểu ô lớn – ô nhỏ với 3 lần nhắc lại, được thực hiện trong vụ Xuân 2018 trên đất phù sa chuyên trồng lạc của huyện Lệ Thủy, tỉnh Quảng Bình nhằm đánh giá ảnh hưởng của liều lượng lưu huỳnh đến năng suất lạc và hiệu quả kinh tế. Kết quả cho thấy liều lượng lưu huỳnh có ảnh hưởng đến các chỉ tiêu như năng suất và hiệu quả kinh tế của hai giống lạc và một số tính chất hóa học đất. Nhìn chung, liều lượng 30 kg S/ha trên nền 40 kg N + 90 kg P2O5 + 60 kg K2O + 500 kg vôi + 8 tấn phân chuồng/ha cho năng suất và hiệu quả kinh tế đạt cao nhất trên cả hai giống lạc, đồng thời cải thiện được một số tính chất hóa học đất.Từ khóa: giống lạc, hiệu quả kinh tế, năng suất, lưu huỳn

PHÂN LẬP PHOMOPSIS SP. N 7.2 SINH TỔNG HỢP LACCASE

SUMMARYAmong 56 strains collected from degraded rice straw, paper and dye effluent samples, 38 strains were positively screened as potentially laccase producers on the solid medium added with enzyme indicators (tannic acid and RBBR) but only two were positive with Syringaldazine. The strains N 7.2 identified as Phomopsis sp. via analysis of its ITS sequence can achieve an laccase activity towards Syringaldazine up to 213,2 UI/ml after 6 days of cultivation. To date, this is the first report on the laccase from Phomopsis sp. SUMMARYAmong 56 strains collected from degraded rice straw, paper and dye effluent samples, 38 strains were positively screened as potentially laccase producers on the solid medium added with enzyme indicators (tannic acid and RBBR) but only two were positive with Syringaldazine. The strains N 7.2 identified as Phomopsis sp. via analysis of its ITS sequence can achieve an laccase activity towards Syringaldazine up to 213,2 UI/ml after 6 days of cultivation. To date, this is the first report on the laccase from Phomopsis sp