The optimal diamond wheels for grinding diamond tools

Grinding is the most suitable process for manufacturing good quality diamond tools. In this paper, diamond wheels have been studied. From the grinding of polycrystalline diamond (PCD) insets, the effects of certain factors such as the bonding material, the grit size and structure of a diamond wheel have been investigated. It is concluded that vitrified bond diamond wheels are the most suitable for grinding PCDs and the recommended grit size is mesh number 1000, which can get a good surface quality within an appropriate time. The wheel structure is another important factor. Rougher wheels (mesh #800, #1000) with the softer grade scale P yield a higher material removal rate (MRR) than scale Q. However, a finer wheel (mesh #1200) needs a tougher structure to promote its grinding ability and to have a higher MRR.     

基于RFID技术的仓库综合管理系统

为保证大型物流企业仓库的安全,提高仓储效率,提出了一种基于RFID技术构建综合仓库管理系统的思路与方法.系统具有报警功能,可对货物自动进行存储统计.介绍了系统的结构、模块的功能、硬件设计以及软件设计的系统流程,阐述了基于动态二进制的系统防碰撞算法.     

不同压力温度条件下聚合的Si-Ni-B中介聚晶金刚石(PCD)抗压强度及组织特征研究

在一系列高温超高压条件下,制备了Si-Ni-B中介结合的聚晶金刚石(PCD),用压缩试验、X射线衍射分析、SEM、金相分析研究了PCD聚合的温度、压力条件对其抗压强度及组织特征的影响。     

精密、超精密加工时 PCD 刀具后刀面错位熨压的理论模型及实验研究

对精密、超精密加工时ＰＣＤ刀具后刀面的熨压作用进行了分析,建立了后刀面错位熨压的理论模型,并通过实验研究了后刀面的错位熨压作用,对提高加工表面质量有指导意义。     

The Calcium-Dependent Protein Kinase TaCDPK27 Positively Regulates Salt Tolerance in Wheat

As essential calcium ion (Ca²⁺) sensors in plants, calcium-dependent protein kinases (CDPKs) function in regulating the environmental adaptation of plants. However, the response mechanism of CDPKs to salt stress is not well understood. In the current study, the wheat salt-responsive gene TaCDPK27 was identified. The open reading frame (ORF) of TaCDPK27 was 1875 bp, coding 624 amino acids. The predicted molecular weight and isoelectric point were 68.905 kDa and 5.6, respectively. TaCDPK27 has the closest relationship with subgroup III members of the CDPK family of rice. Increased expression of TaCDPK27 in wheat seedling roots and leaves was triggered by 150 mM NaCl treatment. TaCDPK27 was mainly located in the cytoplasm. After NaCl treatment, some of this protein was transferred to the membrane. The inhibitory effect of TaCDPK27 silencing on the growth of wheat seedlings was slight. After exposure to 150 mM NaCl for 6 days, the NaCl stress tolerance of TaCDPK27-silenced wheat seedlings was reduced, with shorter lengths of both roots and leaves compared with those of the control seedlings. Moreover, silencing of TaCDPK27 further promoted the generation of reactive oxygen species (ROS); reduced the activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT); aggravated the injury to photosystem II (PS II); and increased programmed cell death (PCD) in wheat leaves under NaCl treatment, confirming that the TaCDPK27-silenced seedlings exhibited more NaCl injury than control seedlings. Taken together, the decrease in NaCl tolerance in TaCDPK27-silenced seedlings was due to excessive ROS accumulation and subsequent aggravation of the NaCl-induced PCD. TaCDPK27 may be essential for positively regulating salt tolerance in wheat seedlings.     

针对EMVLevel1 Analog Test认证的金融支付PCD设计与调试

文章针对最新版EMV Level 1标准,对PCD的EMV Level 1 Analog test认证的检测环境及检测项目进行总结,对实际测试中可能遇到的问题进行分析,总结出其技术难点。针对这些难点提出PCD设计中需要重点关注的方面以及设计技巧,进一步给出调试中使用怎样的方法达到系统的最优配置,成功通过EMV Level1 Analog test的检测。     

等离子体室内空气净化技术研究成果与探讨

讨论了绝缘屏障放电和脉冲电晕放电应用于空气净化的实验,并比较了实验结果;研究了用交流屏障型等离子体反应器进行香烟烟雾气味控制的实验,并对结果进行了分析;阐述了等离子体杀菌消毒的原理,研究了不同菌种的平面试样实验。     

Dynamic Changes in Reactive Oxygen Species in the Shoot Apex Contribute to Stem Cell Death in Arabidopsis thaliana

In monocarpic plants, stem cells are fated to die. However, the potential mechanism of stem cell death has remained elusive. Here, we reveal that the levels of two forms of reactive oxygen species (ROS), superoxide anion free radical (O2·−) and hydrogen peroxide (H₂O₂), show dynamic changes in the shoot apex during the plant life cycle of Arabidopsis thaliana. We found that the level of O2·− decreased and disappeared at four weeks after bolting (WAB), while H₂O₂ appeared at 3 WAB and showed a burst at 5 WAB. The timing of dynamic changes in O2·− and H₂O₂ was delayed for approximately three weeks in clv3-2, which has a longer lifespan. Moreover, exogenous application of H₂O₂ inhibited the expression of the stem cell determinant WUSCHEL (WUS) and promoted the expression of the developmentally programmed cell death (dPCD) marker gene ORESARA 1 (ORE1). These results indicate that H₂O₂ triggers an important signal inducing dPCD in stem cells. Given that O2·− plays roles in maintaining WUS expression and stem cell activity, we speculate that the dynamic shift from O2·− to H₂O₂ in the shoot apex results in stem cell death. Our findings provide novel insights for understanding ROS-mediated regulation during plant stem cell death.     

三角形PCD的质量状况及应用前景

三角形PCD的剪切破岩方式使其在塑性、塑脆性地层钻进效果较好.国产三角形PCD石油钻头难以见到应有的效果,碎断齿现象严重.通过检测国内外三角形PCD产品性能发现:国产三角形PCD的抗冲击韧性大大低于行业标准规定值;同一批产品的磨耗比数值差异较大;由于自锐性差,在测定磨耗比过程中,当其尖角磨损面较大时易出现发红现象;与国外同类产品相比有较大差距.采用以1/3的圆柱形(80°～85°锥角)PCD替代三角形PCD制作的混合齿钻头,使用效果有明显改善,但仍难以取代三角形PCD钻头在钻进某些地层的特殊作用.国产高质量三角形PCD钻头将会为提高日益增多的超深井复杂地质条件下的钻进效果发挥其应有的作用.     

用铁基烧结助剂制备金刚石聚晶的研究

通过高温高压下金刚石再生长烧结方法，采用细粒度金刚石微粉作原料，铁基金属微粉作烧结助剂，在六面顶超高压设备上进行了金刚石聚晶的制备。研究了铁基金属和金刚石微粉体系再生长烧结的温度压力条件，并通过高倍光学显微镜、扫描电镜(SEM)、X—ray衍射、Raman光谱等测试手段对金刚石聚晶样品进行了内部成分和微观形貌分析。研究结果表明，在5．8GPa，1550℃条件下制备的PCD材料内部比较均匀致密。X—ray衍射和Raman光谱测试结果表明，在更高的温度条件下制备的样品内部有少量的石墨化。另外，样品内部还有部分碳化铁的存在。因此，我们认为，用Fe基烧结助剂制备的PCD材料内部除存在金刚石的自成键外，还有金刚石与金刚石之间通过铁碳键把金刚石烧结在一起的一种机制。