高效液相色谱-电感耦合等离子质谱法分析海洋沉积物中有机锡的形态

建立了高效液相色谱-电感耦合等离子质谱(HPLC-ICP-MS)测定海洋沉积物中二丁基锡(DBT)、三丁基锡(TBT)、二苯基锡(DPhT)及三苯基锡(TPhT)的形态分析方法。通过改变流动相组分比例,使4种有机锡达到基线分离。比较不同提取方法对标准参考物质PACA-2中有机锡的提取效率。以V(乙腈)∶V(H2O)∶V(乙酸)=55∶33∶12(含5%三乙胺,pH 3.0)为提取剂时,超声提取效率最高(>91.5%),其加标回收率均大于96%。本方法对DBT,TBT,DPhT和TPhT的检出限分别达到0.7,0.75,0.45和0.4μg/kg。对浓度范围为0.5～100μg/kg有机锡混合标准溶液进行测定,4种有机锡回归系数均大于0.998。利用本方法对几种海洋沉积物样品和海产品中的有机锡进行测定,在部分沉积物样品中检测到了DBT和TBT,部分海产品中测到了少量TBT和TPhT。     

超声搅拌化学浴沉积法制备大颗粒和致密的CdS薄膜

采用超声搅拌化学浴法(UCBD)在SnO2:F透明导电玻璃衬底上制备了CdS薄膜.研究了退火和CdCl2处理对UCBD-CdS薄膜的表面形貌、晶体结构和直接带隙的影响,比较了沉积时间对UCBD-CdS薄膜中CdS聚集体颗粒大小和堆积致密性的影响.结果表明,CdCl2处理可使CdS聚集体中的小颗粒重新熔合在一起,但CdS聚集体的大小并没有改变.在UCBD-CdS薄膜的沉积过程中,CdS薄膜的横向和纵向生长速率之比会随着沉积时间的不同而改变,且沉积时间是获得大颗粒的CdS聚集体和致密的UCBD-CdS薄膜的重要影响因素.当沉积时间为40min时,获得的UCBD-CdS薄膜较致密,CdS聚集体的大小为180nm,膜厚为80.8nm,适合作为薄膜太阳电池的窗口层.     

Fast Electrochemical Characterization of Historical Glasses Using Carbon Screen‐Printed Electrodes and Ultrasonic Assisted Sampling

A new method for lead oxide (PbO) analysis in glasses, using a carbon screen printed electrode (SPE) is proposed. A suspension of the powdered glass sample in nitric acid is prepared using an ultrasonic probe, 100 µL of slurry are deposited on the SPE and the voltammetric measurement is carried out. Structural information of PbO in the glass matrix is obtained by CV. Lead quantification is performed by DPV. In the best conditions a LOD of 2.30 wt% of PbO was obtained. The method has been applied with good results in the analysis of historical glasses samples.     

Sulfur removal from bauxite water slurry (BWS) electrolysis intensified by ultrasonic

Effects of ultrasonic on desulfurization ratio from bauxite water slurry (BWS) electrolysis in NaOH solution were examined under constant current. The results indicated that ultrasonic improved the desulfurization ratio at high temperatures because of the diffusion and transfer of oxygen gas in electrolyte. However, due to the increase in oxygen gas emission, ultrasonic could not improve the desulfurization ratio obviously at low temperatures. Additionally, the particle size of bauxite became fine in the presence of ultrasonic, indicating that the mass transfer of FeS₂ phase was improved. According to the polarization curves, the current density increased in the presence of ultrasonic, indicating that the mass transfer of liquid phase was improved. The apparent activation energy (AAE) of electrode reaction revealed that ultrasonic did not change the pathway of water electrolysis. However, ultrasonic changed the pathway of BWS electrolysis, converting indirect oxidation into direct oxidation. The AAE of BWS electrolysis in the presence of ultrasonic was higher than that in the absence of ultrasonic. And the low AAEs (less than 20 kJ/mol) clearly indicated the diffusion control during BWS electrolysis reaction.     

基于ABAQUS的微细电火花超声振动主轴 仿真研究*

微细电火花技术凭借自身的特点和优势,在航空航天、医疗器械等领域发挥着重要的作用。超声振动辅助电火花加工在传统电火花加工中引入超声振动,加工精度和加工效率明显提高。作为核心部件,超声振动主轴的设计尤为重要。但传统设计过程,大大延长了研发周期和增加了成本,,因此,采用仿真方式进行研究具有重要的意义。本文对设计的微细电火花超声振动主轴的进行了仿真研究,通过ABAQUS进行了模态分析和谐响应分析,得到了超声振动主轴的谐振频率和输出振幅等参数。超声振动主轴的测试实验验证了仿真结果的正确性。     

Effect of Ultrasonic‐assisted Preparation Methods on Structure,Morphology and Optical Properties of Nanosized Cupric Oxide

Cupric oxide is a p‐type semiconductor with a narrow band‐gap which is suitable for catalysis, electrochemical cells, field emission devices and gas sensor applications. Despite considerable efforts devoted to the preparation of the nanosized CuO, there is a lack of information about ultrasonic‐assisted (US) preparation methods. Nanosized cupric oxide was successfully prepared through different ultrasonic‐assisted (US) preparation methods. Furthermore, the influence of preparation method on the structure, morphology and optical properties of nanosized CuO has been reported. XRD patterns were identical to the single‐phase pure CuO with a monoclinic structure. The enhancement of the crystallinity and crystallite size was observed for the sample prepared through the US thermal decomposition. The absorption band of CuO nanocrystals prepared through the US liquid hydrolysis shows a clear red shift of about 40 nm compared to those obtained with other preparation methods. Our results indicated that almost spherical CuO nanoparticles with an average size of 65 nm were prepared during the US thermal decomposition, while CuO rod‐like nanostructures with an average diameter of about 16 nm were obtained via the US liquid hydrolysis method. The band gap values of nanosized CuO samples were larger than the reported value for the bulk CuO. Synthesized CuO samples by US methods with adjustable and controllable properties make the applicability of cupric oxide even more versatile.     

Analysis of benzophenone and 4-methylbenzophenone in breakfast cereals using ultrasonic extraction in combination with gas chromatography-tandem mass spectrometry (GC-MS)

Benzophenone (BP) and 4-methylbenzophenone (4MBP) are photo-initiators that are generally used to cure ink on carton boards.In this contribution, a fast and reliable method for the determination of BP and 4MBP in breakfast cereals is described. The sample was extracted ultrasonically using a mixture of dichloromethane and acetonitrile (1:1), followed by a clean-up of the extract using solid phase extraction with a silica cartridge. Finally, the extract was analysed by GC-MSⁿ. Benzophenone-d₁₀ was used as internal standard. The presented method is validated in terms of linearity, recovery, repeatability and intra-laboratory reproducibility, specificity, limit of detection and limit of quantification. In conclusion, this method is able to detect both BP and 4MBP at very low concentrations (LOD = 2 μg kg⁻¹) in breakfast cereals.     

Ultrasonic velocity of binary systems at elevated pressures

Various empirical theories of ultrasonic velocity have been applied to three binary liquid mixtures, under pressures up to 200 MPa and their validity have been tested. A pressure dependent study of ultrasonic velocities has been made at 303.15 K. The agreement between theory and experiment is found to be quite satisfactory.     

The influence of magnetic field swept rate on the ultrasonic propagation velocity of magnetorheological fluids

Structure of magnetorheological (MR) fluids depends on the strength of the magnetic field applied and on the mode of its application. The ultrasonic wave propagation velocity changes under the effect of an external magnetic field as a result of formation of clusters arranged along the direction of the field in the MR fluids. Therefore, we propose a qualitative analysis of these clustering structures by measuring properties of ultrasonic propagation. Since the MR fluids are opaque, the non-contact inspection using this ultrasonic technique can be very useful. In this study, we measured ultrasonic propagation velocity in MR fluid influenced by an external magnetic field for different swept rate precisely. With increasing magnetic field intensity, the changes of the ultrasonic wave velocity are more pronounced. Sedimentation effect takes place in certain time for different swept rate due to magnetic particle size and it follows linear relationship in log scale. Significant differences of the ultrasonic wave velocity are established between the case when the field is swept at a constant rate and the case when it is stepped up.     

Ultrasonic‐Assistance and Aging Time Effects on the Zeolitation Process of BZSM‐5 Zeolite

The isomorphic substitution of boron into ZSM‐5 zeolite under static hydrothermal condition was investigated. Evaluation of hydrothermal synthesis of BZSM‐5 was performed by treating the synthesis mixture by different aging processes, namely, ultrasonic, static, stirring, and microwave‐assisted aging prior to the conventional hydrothermal treatment. The synthetic processes with different techniques of aging prior to the onset of conventional hydrothermal crystallization were compared with a process without any prior aging. The obtained results showed that the ultrasonic and microwave assisted aging shortened the crystallization time and altered the crystal size and the morphology of the obtained products. The characteristics of the synthesized products were obtained by FT‐IR spectroscopic, XRD and SEM techniques.