A novel Mg-Gd-Y-Zn-Cu-Ni alloy with excellent combination of strength and dissolution via peak-aging treatment

Inferior absolute strength and dissolution properties are the main bottlenecks for the widespread application of dissolvable magnesium alloys in complex working environments for unconventional oil and gas resources.Here,a novel functional peak-aged Mg-9.5Gd-2.7Y-0.9Zn-0.8Cu-0.4Ni(wt.%) alloy for fracturing tools is reported,and it possesses an ultimate tensile strength of 457.6 MPa,ultimate compressive strength of 620.7 MPa and dissolution rate of ~43.7 mg·cm^(-2)·h^(-1) in 3 wt.% KCl solutions at 93℃.The excellent strength of the agedalloy is primarily attributed to the combination of grain refinement,long-period stacking ordered(LPSO) strengthening,and precipitation strengthening induced by stacking fault and β’ phase,among which the precipitation strengthening is dominant.Further investigations confirm that the corrosion is triggered from the micro-galvanic coupling between the Mg matrix and the cathodic lamellar and block LPSO phases.Strip-shaped corrosion pits along with LPSO phases are subsequently formed,significantly accelerating corrosion.The β’ precipitates can effectively improve the strength without compromising the dissolution rate because of their nanoscale size.This study provides an excellent material selection for dissolvable fracturing tools and presents a strategy by which a synergistic combination of strength and dissolution rate is achieved via peak-aging treatment.

Effects of Organic and Chemical Fertilizations and Microbe Inoculation on Physiology and Growth of Sweet Corn Plants

A pot culture experiment was carried out in a glasshouse to compare the physiology and growth of sweet corn plants (Zea mays L. cv. Honey Bantam) grown under organic and chemical fertilizations with or without microbial inoculation (MI). The organic fertilizer used was fermented mainly using rice bran and oil mill sludge, and the MI was a liquid product containing many beneficial microbes such as lactic acid bacteria, yeast, photosynthetic bacteria and actinomycetes. The application amounts of the organic fertilizer and chemical fertilizers were based on the same rate of nitrogen, phosphorus and potassium. Sweet corn plants fertilized with organic materials inoculated with beneficial microbes grew better than those without inoculation. There were no significant differences in physiology and growth of the sweet corn plants between treatments of chemical fertilizers with and without MI. Among the organic fertilization treatments, only the sweet corn plants with organic fertilizer and MI applied 4 weeks before sowing had similar photosynthetic capacityj total dry matter yield and ear yield to those with chemical fertilizers. Sweet corn plants in other organic fertilization treatments were weaker in physiology and growth than those in chemical fertilization treatments. There was no significant variance among chemical fertilization treatments at different time. It is concluded from this research that this organic fertilizer would be more effective if it was inoculated with the beneficial microbes. Early application of the organic fertilizer with beneficial microbes before sowing was recommended to make the nutrients available before the rapid growth at the early stage and obtain a yield similar to or higher than that with chemical fertilizations.

受到漏汽激振的转子—轴承系统门槛性能的优化

涡轮机械叶片顶部的流体泄漏可诱发不稳定性并限制出力。本文应用优化技术找得轴远直么和轴承支撑，使优化的转子－轴承系统可承受较大的流体漏汽激振力。结果表明，略加改变轴径即可显著改善转子－轴承系统的门槛性能。结果还表明，优化轴承支撑和优化轴径相组合可更显著改善门槛性能。

STCF conceptual design report (Volume 1): Physics & detector

The superτ-charm facility(STCF)is an electron–positron collider proposed by the Chinese particle physics community.It is designed to operate in a center-of-mass energy range from 2 to 7 GeV with a peak luminosity of 0.5×10^(35) cm^(–2)·s^(–1) or higher.The STCF will produce a data sample about a factor of 100 larger than that of the presentτ-charm factory—the BEPCII,providing a unique platform for exploring the asymmetry of matter-antimatter(charge-parity violation),in-depth studies of the internal structure of hadrons and the nature of non-perturbative strong interactions,as well as searching for exotic hadrons and physics beyond the Standard Model.The STCF project in China is under development with an extensive R&D program.This document presents the physics opportunities at the STCF,describes conceptual designs of the STCF detector system,and discusses future plans for detector R&D and physics case studies.

Two-stage Hall-Petch relationship in Cu with recrystallized structure

Although Cu was studied extensively,the Hall-Petch relationship was mainly reported in the coarsegrained regime.In this work,fully recrystallized Cu specimens with a wide grain size regime of 0.51–14.93μm manifest a two-stage Hall-Petch relationship.There is a critical grain size of 3μm that divides stagesⅠandⅡwhere the Hall-Petch slope k value are quite different.The stageⅡis supposed to be validified down to 100 nm at least by comparing with a Cu-Ag alloy.The critical grain size varies in different materials systems,and the underline mechanisms are discussed based on the dislocation glide modes.