Food demand and soil sustainability have become urgent issues recently because of the global climate changes. This study aims to evaluate the application of a biochar produced by rice hull, on changes of physiochemical characteristics and erosion potential of a degraded slopeland soil. Rice hull biochar pyrolized at 400°C was incorporated into the soil at rates of 2.5%, 5%, and 10% (w/w) and was incubated for 168 d in this study. The results indicated that biochar application reduced the Bd by 12% to 25% and the PR by 57% to 92% after incubation, compared with the control. Besides, porosity and aggregate size increased by 16% to 22% and by 0.59 to 0.94 mm, respectively. The results presented that available water contents significantly increased in the amended soils by 18% to 89% because of the obvious increase of micropores. The water conductivity of the biochar-amended soils was only found in 10% biochar treatment, which might result from significant increase of macropores and reduction of soil strength (Bd and PR). During a simulated rainfall event, soil loss contents significantly decreased by 35% to 90% in the biochar-amended soils. In conclusion, biochar application could availably raise soil quality and physical properties for tilth increasing in the degraded mudstone soil.

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The ultra-low spacing of patterned sliders flying above a rotating disk with smooth surface in a hard disk drive is analyzed for high areal density recording. Three types of pattern (slender, square, and broad) with the same bump area are discussed. The molecular gas film lubrication (MGL) equation and the equations of motion of the patterned slider are solved numerically to obtain the steady flying attitude. The results show that the flying height of the broad patterned slider is the greater than either that of the square patterned slider or the slender patterned slider. In addition, we analyzed the effects of bump height and the bump pitch on the slider attitude, including flying heights, pitch angles, and roll angles, are discussed. Keywords patterned slider, molecular gas lubrication, flying attitude IntroductionThe trend of reducing the flying spacing of a magnetic head slider to increase the areal recording density of a hard disk drive encounters a strict challenge in tribology. Besides the load/unload technology, the disk surfaces are always textured to reduce the bearing area, and thus the torque required to start the hard disk drive Some designs try to transfer part of the texture from the disk to the slider [6][7][8]. The birth of the padded slider [7,8] has the benefit of reducing the head/disk interaction and controlling friction during contact start and stop. In addition to the mechanical and laser texture, some artificial bumps, which are much larger than the laser bumps and much smaller than the pads, are fabricated on the sliders. Tagawa and Bogy [9] analyzed the air film dynamics for micro-textured flying head slider bearings in magnetic HDD. The two dimensional textures were modeled as deterministic rectangles in the transverse and longitudinal directions. The effects of 'transverse microtextures' spacing and depth on the air film dynamics were investigated in detail numerically.Artificial bump is achievable for the present improvement of microelectromechanical system (MEMS) fabrications. From the MEMS process for magnetic head slider, the slider surfaces can be patterned simultaneously. The texturing processes on disks can be reduced. Although they still have to meet the meniscus problems as the spindle motor starts to rotate. Our objective in this study was to analyze the pattern slider with three kinds of bump patterns (broad, square, and slender), to analyze numerically the flying attitudes by solving the molecular gas film lubrication equation and the equations of motion of the slider simultaneously, and to analyze the effects of bump heights and bump pitches on the flying attitudes. Numerical simulationThe simulation models for micro-textured flying head sliders are shown in Fig. 1(a-c). Three kinds of pattern are considered, including slender (20 lm · 5 lm), square (10 lm · 10 lm), and broad (5 lm · 20 lm). Three columns of bumps are generated in each rail. The bump height is d and the bump pitch in the longitudinal direction is r. For further comparison, the bump area for the ...

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