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Tetsuo Irifune Chiaki Ueda Shohei Ohshita Hiroaki Ohfuji Takehiro Kunimoto Toru Shinmei 《高压研究》2020,40(1):96-106
ABSTRACTNano-polycrystalline diamond (NPD) with various grain sizes has been synthesized from glassy carbon at pressures 15–25?GPa and temperatures 1700–2300°C using multianvil apparatus. The minimum temperature for the synthesis of pure NPD, below which a small amount of compressed graphite was formed, significantly increased with pressure from ~1700°C at 15?GPa to ~1900°C at 25?GPa. The NPD having grain sizes less than ~50?nm was synthesized at temperatures below ~2000°C at 15?GPa and ~2300°C at 25?GPa, above which significant grain growth was observed. The grain size of NPD decreases with increasing pressure and decreasing temperature, and the pure NPD with grain sizes less than 10?nm is obtained in a limited temperature range around 1800–2000°C, depending on pressure. The pure NPD from glassy carbon is highly transparent and exhibits a granular nano-texture, whose grain size is tunable by selecting adequate pressure and temperature conditions. 相似文献
3.
Development of bioanalytical methods for selective and accurate detection of H2S in living samples is essential for understanding the pathological and physiological functions of this gasotransmitter in biological systems. Here we report a Golgi apparatus-targetable lanthanide complex-based luminescent probe, Golgi-ABTTA-Eu3+/Tb3+, that can be used for accurately determining H2S in aqueous solution and living cells via the ratiometric time-gated luminescence (RM-TGL) technique. This probe is composed of 2,2′:6′,2′′-terpyridine-Eu3+/Tb3+ mixed complexes as the luminophore, 4-azidobenzyl-ether as the responsive moiety, and sulfanilamide as the Golgi apparatus-targeting moiety. Upon reaction with H2S, accompanied by the cleavage of 4-azidobenzyl group from the probe molecule, the long-lived emission of Tb3+ complex at 540 nm is significantly enhanced, while that of Eu3+ complex at 610 nm is obviously reduced. It was noted that the I540/I610 ratio increased by 8.8 times after the probe was exposed to H2S, which enabled H2S to be detected with RM-TGL method. After being incubated with living cells, the probe molecules were selectively accumulated in the Golgi apparatus, which allowed H2S in the Golgi apparatus to be successfully imaged in RM-TGL mode. 相似文献
4.
Karoll Ferrer Katy Díaz Miroslav Kvasnica Andrs F. Olea Mauricio Cuellar Luis Espinoza 《Molecules (Basel, Switzerland)》2021,26(4)
The metabolism of brassinosteroid leads to structural modifications in the ring skeleton or the side alkyl chain. The esterification and glycosylation at C-3 are the most common metabolic pathways, and it has been suggested that conjugate brassinosteroids are less active or inactive. In this way, plants regulate the content of active brassinosteroids. In this work, the synthesis of brassinosteroid 24-norcholane type analogs conjugated at C-3 with benzoate groups, carrying electron donor and electron attractant substituents on the aromatic ring, is described. Additionally, their growth-promoting activities were evaluated using the Rice Lamina Inclination Test (RLIT) and compared with that exhibited by brassinolide (used as positive control) and non-conjugated analogs. The results indicate that at the lowest tested concentrations (10−8–10−7 M), all analogs conjugated at C-3 exhibit similar or higher activities than brassinolide, and the diasteroisomers with S configuration at C-22 are the more active ones. Increasing concentration (10−6 M) reduces the biological activities of analogs as compared to brassinolide. 相似文献
5.
The mechanical behaviour of the upper layers of a sandy loam soil was studied under standard triaxial compression and direct shear box tests. Variations of soil material properties were investigated at four different initial dry bulk densities of 1410, 1520, 1610 and 1670 kg/m3. Soil deformation and volume change under the triaxial compression loading were also studied at these bulk densities. Results from the two tests showed increases in the soil mechanical properties with the initial dry bulk density. The internal friction angle values measured with the triaxial compression apparatus exceeded those measured with the direct shear box. In contrast, the soil cohesion values measured with the direct shear box exceeded those measured with the triaxial compression apparatus. Under the triaxial compression test, the loose soil samples underwent contraction and volume reduction, whereas the dense samples swelled and failure cracks appeared clearly at various planes. The soil contraction for the former case characterizes the occurrence of soil compaction, whereas the cracks propagation and volume increase in the latter case characterizes the breaking up and loosening of soil during tillage operations. For the loose and moderately compacted states, the engineering Poisson's ratio increased with the axial strain until loading was completed. It also increased at the compacted and very compacted states until reaching given loading stages, after which its value started to decrease. This shifting in the engineering Poisson's ratio during loading may provide another identification of the moment of soil failure occurrence, in addition to that of the maximum shear stress. 相似文献
6.
在上部为花岗岩块石填土、下部为相对软弱的粘性土 ,地下水与海水相通的地区进行大型工程建设 ,主要建 (构 )筑物采用桩基础是安全可靠的措施 ,但采用何种桩型、沉桩时怎样才能顺利穿过花岗岩块石填土是一个值得研究的课题。采用潜孔锤引孔穿过花岗岩块石填土 ,往孔内回填碎石 ,然后打H型钢桩 ,在深圳某电厂地基处理中获得了较好的效果 相似文献
7.
Optimum step-stress
accelerated
degradation
test
for Wiener degradation
process
under
constraints 总被引:1,自引:0,他引:1
To assess a product's reliability for subsequent managerial decisions such as designing an extended warranty policy and developing a maintenance schedule, Accelerated Degradation Test (ADT) has been used to obtain reliability information in a timely manner. In particular, Step-Stress ADT (SSADT) is one of the most commonly used stress loadings for shortening test duration and reducing the required sample size. Although it was demonstrated in many previous studies that the optimum SSADT plan is actually a simple SSADT plan using only two stress levels, most of these results were obtained numerically on a case-by-case basis. In this paper, we formally prove that, under the Wiener degradation model with a drift parameter being a linear function of the (transformed) stress level, a multi-level SSADT plan will degenerate to a simple SSADT plan under many commonly used optimization criteria and some practical constraints. We also show that, under our model assumptions, any SSADT plan with more than two distinct stress levels cannot be optimal. These results are useful for searching for an optimum SSADT plan, since one needs to focus only on simple SSADTs. A numerical example is presented to compare the efficiency of the proposed optimum simple SSADT plans and a SSADT plan proposed by a previous study. In addition, a simulation study is conducted for investigating the efficiency of the proposed SSADT plans when the sample size is small. 相似文献
8.
随着科学技术的发展,对粒子的大小、浓度及其他特性的探测已经发展成为一个专门的研究领域和现代测量学中的一个重要分支,而光散射法已经成为一种常用的粒子测量方法。为了满足应用需求,文中提出了一种基于C8051F500单片机的光静态散射测试系统方案,详细介绍了该测试系统的设计理论原理、硬件电路的设计依据、固件程序的设计思想和测试系统的具体实现。选取一定浓度的样品溶液,运用该系统进行光散射的角度依赖性测试,实际测量值与理论依据基本相符;在不同激光功率下,对同一角度的散射光强进行测试,将测量得到的数据分析,线性度良好,满足设计要求。 相似文献
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