首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 0 毫秒
1.
研究了CO2,Ar离化团束对不同金属系统及SiO2表面的溅射效应。离化团束的溅射产额比之单体离子束高100倍以上。气体离化团束的高溅射产额可能是由于多体碰撞、侧向溅射及高能量密度的照射引起的。  相似文献   

2.
New data concerning the influence of a probing beam of bismuth ions on the depth resolution in elemental depth profiling by secondary ion mass spectrometry (SIMS) have been obtained on a TOF.SIMS-5 system using the principle of two separate ion beams. It is established that the existing criterion of nondestructive character of the probing beam, on which this principle is based, is insufficient. Additional processes must be taken into account so as to formulate a more adequate criterion. A regime of depth profiling is proposed that allows the depth resolution to be improved at low energies of sputtering ions.  相似文献   

3.
Potassium‐ion batteries (PIBs) configurated by organic electrodes have been identified as a promising alternative to lithium‐ion batteries. Here, a porous organic Polyimide@Ketjenblack is demonstrated in PIBs as a cathode, which exhibits excellent performance with a large reversible capacity (143 mAh g?1 at 100 mA g?1), high rate capability (125 and 105 mAh g?1 at 1000 and 5000 mA g?1), and long cycling stability (76% capacity retention at 2000 mA g?1 over 1000 cycles). The domination of fast capacitive‐like reaction kinetics is verified, which benefits from the porous structure synthesized using in situ polymerization. Moreover, a renewable and low‐cost full cell is demonstrated with superior rate behavior (106 mAh g?1 at 3200 mA g?1). This work proposes a strategy to design polymer electrodes for high‐performance organic PIBs.  相似文献   

4.
An ion exchanger was prepared by sulfonation of cork-waste chars. The exchange properties of the resultant material were characterized using Na+, Ca2+ or Fe3+ aqueous solutions. The content of metal ions in the solutions were determined by atomic absorption spectrometry. On the basis of the results obtained, the chemical equilibrium and its thermodynamic aspects related to the ion exchange process were studied. It was found that equilibrium constant K varies by the order: Na+0 and △5°>0, with -△G° following the sequence: Ca2+>Na+>Fe3+.  相似文献   

5.
6.
The capacity of anode materials plays a critical role in the performance of lithium‐ion batteries. Using the nanocrystals of oxygen‐free metal‐organic framework ZIF‐67 as precursor, a one‐step calcination approach toward the controlled synthesis of CoO nanoparticle cookies with excellent anodic performances is developed in this work. The CoO nanoparticle cookies feature highly porous structure composed of small CoO nanoparticles (≈12 nm in diameter) and nitrogen‐rich graphitic carbon matrix (≈18 at% in nitrogen content). Benefiting from such unique structure, the CoO nanoparticle cookies are capable of delivering superior specific capacity and cycling stability (1383 mA h g?1 after 200 runs at 100 mA g?1) over those of CoO and graphite.  相似文献   

7.
运用模块化的设计构想,将等离子体增强原子层沉积工艺单元、热型原子层沉积工艺单元,直流磁控溅射单元和射频磁控溅射工艺单元进行高度优化集成,研制了集束型多层纳米薄膜沉积设备。设备创新采用真空旋转传输平台,替代了传统集成设备的机械手结构,实现了样品在高真空(5×10-5 Pa)中传输,而且传输速度快(2~3 s),有效地减少污染,保证样品表面物性的稳定。设备可在全真空的环境下,实现多层纳米薄膜的制备,同时可以对薄膜生长实现原子层精度的控制。设备的磁控溅射工艺平台可以安装金属掩膜板,直接制备图形薄膜。另外设备具有非常灵活的扩展性,针对薄膜工艺需求的不同,可以集成其他的薄膜制备工艺单元。  相似文献   

8.
The research and developments of a new type of inorganic ion exchanger,crystalline silicotitanate(CST) are reviewed.This material is stable against radiation,and the CST has high selectivity for Cs over Na, K and Rb.It performs well in acidic,neutral,and basic solutions.The results of ion exchange tests show that CST is an excellent candidate for Cs removal from high-level liquid waste.  相似文献   

9.
10.
光学发射光谱(OES)方法是等离子体诊断的有力工具之一,可以定量地给出等离子体的多种重要参数,如等离子体中的物种成分、粒子能态分布、激发温度、粒子相对密度等.本文介绍了一种用于电子回旋共振(ECR)微波等离子体磁控溅射靶附近的增强放电和直流辉光放电等离子体空间分辨诊断的发射光谱装置.其特点是光学收集系统的位置可以水平精细移动,因而可以对放电区域进行空间分辨发射光谱测量.作者利用这套装置对氩气的ECR微波等离子体和直流辉光放电等离子体进行诊断.在ECR微波等离子体的下游区内氩离子谱线的发射强度很弱,主要是高激发态原子的辐射.在磁共振增强放电区,离子谱线强度有所增加但仍比原子谱线弱,类似于直流辉光放电正柱区的光发射特性.  相似文献   

11.
Gold colloidal nanoparticles (GNPs) were prepared by reducing a complex of Au+. Na3Au(SO3)2 with sodium citrate. The procedure provides control of the dimension of nanoparticles produced, which is a function of reaction time and concentration of reactants. The nanoparticles were separated by centrifugation and their characteristics and dimensions were studied using UV-Vis and IR spectroscopy and transmission electronic microscopy (TEM).  相似文献   

12.
ABSTRACT

Gold colloidal nanoparticles (GNPs) were prepared by reducing a complex of Au+. Na3Au(SO3)2 with sodium citrate. The procedure provides control of the dimension of nanoparticles produced, which is a function of reaction time and concentration of reactants. The nanoparticles were separated by centrifugation and their characteristics and dimensions were studied using UV-Vis and IR spectroscopy and transmission electronic microscopy (TEM).  相似文献   

13.
本文对于溶液均相共沉淀法制备镍铁尖晶石前躯粉体的工艺进行了探索研究。论文以Fe(N02)3和Ni(N02)2的混合溶液为反应物,滴加沉淀剂,进行共沉淀反应。对得到的沉淀产物进行洗涤、过滤、干燥、研磨、压制、烧结制备NiFe2O3尖晶石陶瓷粉体。通过正交试验确定了在共沉淀过程中影响共沉淀颗粒粒度的影响因素的主次顺序依次为:反应温度、搅拌速度、沉淀剂浓度、金属离子浓度;并通过反应温度和沉淀荆浓度对产率的影响试验,最终得到共沉淀反应沉淀的最佳条件。对于所制得的镍铁尖晶石陶瓷粉体检测结果表明:溶液均相共沉淀法得到的镍铁尖晶石前躯体粉末具有纯度高、粒度细的特点,并且制备出的镍铁尖晶石惰性阳极基体材料的强度显著提高。  相似文献   

14.
Nanofluidic diodes are potentially useful in many important applications such as sensing, electronics, and energy conversion. However, the manufacturing of controllable nanopores for nanofluidic diodes is technically challenging. Herein, a nanofluidic diode is designed from a highly programmatic covalent organic framework (COF). Through molecular simulation, remarkable diode behavior is observed in a hybrid-bilayer COF but not in its constituent single-layer COFs. The rectification effect of ion current in the hybrid-bilayer COF is attributed to an asymmetric electrostatic potential across the COF nanopore. Furthermore, a synergistic effect of counterion is unraveled in the hybrid-bilayer COF, and the presence of counterion is found to reduce the entry barrier and facilitate ion transport. The performance of the hybrid-bilayer COF as a nanofluidic diode is comprehensively investigated by varying salt concentration, layer number, interlayer spacing, and slipping. This proof-of-concept simulation study demonstrates the feasibility of the hybrid-bilayer COF as a nanofluidic diode and the finding may stimulate the development of new nanofluidic platforms.  相似文献   

15.

Objective

Reducing the rates of death, trauma and sequelae associated with road accidents is the prime goal of road safety authorities, and success requires having data on victims’ outcomes in the long term. The present study examined the outcome of adult road accident victims one year after their accident.

Design

A follow-up study.

Methods

The cohort comprised 886 injured road-accident victims, aged ≥16 years, and living in the Rhône administrative Département, France (taken from the ESPARR Cohort). Data were collected on victim characteristics at the time of crash, and self-reported outcomes one year later. The population of respondents at the one-year questionnaire follow-up was divided into two categories according to injury severity, as mild-to-moderate (M.AIS < 3) or severe (M.AIS 3+). Qualitative variables were compared between these 2 groups using Chi2 or Fisher exact tests.

Results

At one year post-accident, 45% of the mild-to-moderate injury group versus only 20% of severely injured subjects reported full recovery of health (p < 0.001). 20% of the cohort, as a whole, reported permanent pain. More than half of the severely injured subjects reported that the accident had had an impact on the everyday life of their family; this was twice as many as in the mild-to-moderate injury group (55% vs. 22%). Most of the severely injured reported impact on leisure, projects and emotional life: 20% reported relational difficulties in the couple, 16% reported impaired sexual life, and the rate of separation was significantly higher than in the mild-to-moderate injury group (5% vs. 1%; p < 0.001). Mean time off work was significantly longer in the severe injury group: 245 ± 158 days vs. 75 ± 104 days (p < 0.001); and 32% of the severe injury group (p < 0.001) who had stopped work had not returned at 1 year, compared to 5% of the mild-to-moderate injury group.

Conclusions

One year after a road accident, the consequences for victims remain significant. In terms of physical impact, pain frequently persists, impairing daily life for many. There is an elevated rate of chronic PTSD (post-traumatic stress disorder) and a non-negligible impact on affective and occupational life.  相似文献   

16.
Organic carbon and elemental carbon in Asia: a review from 1996 to 2006   总被引:2,自引:0,他引:2  
The principal sources of organic carbon (OC) and elemental carbon (EC) are anthropogenic or biogenic, whereas secondary sources are atmospheric oxidation processes of specific precursor gases. These compounds are considered atmospheric contaminants and adversely affect human health. Numerous studies have monitored atmospheric particulates and gaseous phases of OC and EC in Asia over the last decade. This work compares and analyzes different sample collection, pretreatment and analytical approaches. The principal carbonaceous sources are traffic exhaust and industrial emissions. The OC and EC concentrations are highest in high traffic areas, followed by urban sites, and lowest in suburban sites. Many characteristics of these sites, such a dense population, are important to research. The major OC to EC ratios in Asia cities were 1.0-3.0. This work elucidates the characteristics, sources, distributions, and characteristics of atmospheric carbonaceous species in Asia.  相似文献   

17.
Consideration is given to the processes of acceleration and heating of metallic particles in the device proposed by the authors for deposition of metallurgical coatings with the use of a short argon arc. The coatings produced are compared to those deposited by the traditional method of plasma spraying. Results of spectroscopic determinations of the temperature fields of the arc are given. The heat-flux density and the temperature of macroparticles are evaluated by the parameters of their destruction in the plasma found experimentally. The high efficiency of the technology proposed for heating of metallic powders, including high-melting ones, is shown.  相似文献   

18.
19.
Radical polymers are aliphatic or nonconjugated polymers bearing organic robust radicals as pendant groups per repeating unit. A large population of the radical redox sites allows the efficient redox gradient‐driven electron transport through the polymer layer by outer‐sphere self‐exchange reactions in electrolyte solutions. The radical polymers are emerging as a new class of electroactive materials useful for various kinds of wet‐type energy storage, transport, and conversion devices. Electric‐field‐driven charge transport by hopping between the densely populated radical sites is also a remarkable aspect of the radical polymers in the solid state, which leads to many dry‐type devices such as organic memories, diodes, and switches.  相似文献   

20.
能量分析器是对荷能粒子进行分析的重要仪器,其在空间粒子探测方面有着越来越广泛的应用。本文基于带电粒子在静电场中的运动理论以及粒子碰撞理论,利用多物理场仿真软件COMSOL,对一种小角度偏转离子能量分析器进行了仿真研究。模拟计算了不同入射离子能量下的离子运动轨迹,分析了不同入射离子能量和微通道板电压对分析器带电粒子通过率和分辨率的影响,同时分析了温度变化对分析器工作性能的影响。计算结果表明,偏转电压与离子能量之间存在线性变化关系;微通道板电压为-300 V时,分析器的能量分辨率效果较好;温度的变化不改变分析器的能量分辨率,但对分析器的离子通过率有影响。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号