一种门式起重机安全监测传感器布设方法

近年来,起重机事故频发,对起重机进行长期、实时安全监测已是大势所趋,设计合理的传感器布设点是保证整个监测系统可靠性的关键所在。提出了基于虚拟仿真技术的传感器布设点选取方法,并以1台L型门式起重机为例系统的阐述了其实现过程。建立虚拟样机,利用有限元分析考察其在典型工况下应力分布,确定应力较大点为传感器的布点位置。通过应变测试进行验证,仿真结果与实际测试结果吻合,证明了此方法是可行的。     

Pressure‐Induced Structural Transition in WO3 Nanowires

Raman spectroscopic analysis is performed on WO₃ nanowires at room temperature at pressures from ambient conditions to 45 GPa. Linear dependence of the first‐order Raman signal on various high‐pressure (HP) sections is observed. Upon increasing the applied pressure, the WO₃ nanowires undergo four phase transitions at pressures around 1.7, 4.6, 21.5, and 26.2 GPa, which are all less than that reported for bulk WO₃. When the pressure is up to 42.5 GPa, a new high‐pressure phase (HP5) appears. This phase has never been reported and is not reversible while unloading the pressure.     

Inline pneumatically assisted atmospheric pressure matrix‐assisted laser desorption/ionization ion trap mass spectrometry

Atmospheric pressure (AP) matrix‐assisted laser desorption/ionization (MALDI) is known to suffer from poor ion transfer efficiencies as compared to conventional vacuum MALDI (vMALDI). To mitigate these issues, a new AP‐MALDI ion source utilizing a coaxial gas flow was developed. Nitrogen, helium, and sulfur hexafluoride were tested for their abilities as ion carriers for a standard peptide and small drug molecules. Nitrogen showed the best ion transport efficiency, with sensitivity gains of up to 1900% and 20% for a peptide standard when the target plate voltage was either continuous or pulsed, respectively. The addition of carrier gas not only entrained the ions efficiently but also deflected background species and declustered analyte–matrix adducts, resulting in higher absolute analyte signal intensities and greater signal‐to‐noise (S/N) ratios. With the increased sensitivity of pneumatically assisted (PA) AP‐MALDI, the limits of detection of angiotensin I were 20 or 3 fmols for continuous or pulsed target plate voltage, respectively. For analyzing low‐mass analytes, it was found that very low gas flow rates (0.3–0.6 l min^?1) were preferable owing to increased fragmentation at higher gas flows. The analyte lability, type of gas, and nature of the extraction field between the target plate and mass spectrometer inlet were observed to be the most important factors affecting the performance of the in‐line PA‐AP‐MALDI ion source. Copyright © 2010 John Wiley & Sons, Ltd.     

Micro-bore titanium housed polymer monoliths for reversed-phase liquid chromatography of small molecules

A new method for the fixation of polymethacrylate monoliths within titanium tubing of up to 0.8 mm I.D. for use as a chromatographic column under elevated temperatures and pressures is described. The preparation of butyl methacrylate–ethylene dimethacrylate-based monolithic stationary phases with desired porous structures was achieved within titanium tubing with pre-oxidised internal walls. The oxidised titanium surface was subsequently silanised with 3-trimethoxysilylpropyl methacrylate resulting in tight bonding of butyl methacrylate porous monolith to the internal walls, providing stationary phase stability at column temperatures up to 110 °C and at operating column pressure drops of >28 MPa. The titanium housed monoliths exhibited a uniform and dense porous structure, which provided peak efficiencies of up to 59,000 theoretical plates per meter when evaluated for the separation of small molecules in reversed-phase mode, under optimal conditions (achieved at 15 μL/min and temperature of 110 °C for naphthalene with a retention factor, k = 0.58). The developed column was applied to the reversed-phase isocratic separation of a text mixture of pesticides.     

Chemometric quality control of chromatographic purity

It is common practice in chromatographic purity analysis of pharmaceutical manufacturing processes to assess the quality of peak integration combined by visual investigation of the chromatogram. This traditional method of visual chromatographic comparison is simple, but is very subjective, laborious and seldom very quantitative. For high-purity drugs it would be particularly difficult to detect the occurrence of an unknown impurity co-eluting with the target compound, which is present in excess compared to any impurity. We hypothesize that this can be achieved through Multivariate Statistical Process Control (MSPC) based on principal component analysis (PCA) modeling. In order to obtain the lowest detection limit, different chromatographic data preprocessing methods such as time alignment, baseline correction and scaling are applied. Historical high performance liquid chromatography (HPLC) chromatograms from a biopharmaceutical in-process analysis are used to build a normal operation condition (NOC) PCA model. Chromatograms added simulated 0.1% impurities with varied resolutions are exposed to the NOC model and monitored with MSPC charts. This study demonstrates that MSPC based on PCA applied on chromatographic purity analysis is a powerful tool for monitoring subtle changes in the chromatographic pattern, providing clear diagnostics of subtly deviating chromatograms. The procedure described in this study can be implemented and operated as the HPLC analysis runs according to the process analytical technology (PAT) concept aiming for real-time release.     

复合光路光学镀膜宽光谱膜厚监控系统

介绍一种复合光路宽光谱膜厚监控系统及其软硬件开发,对系统结构组成和工作原理进行说明。通过增加中间通光孔式的分光镜的复合光路,基于LabVIEW平台开发宽光谱膜厚监控软件,实现了基于宽光谱扫描法的宽光谱膜厚监控和基于极值法的光学膜厚监控的兼容并用,提高了光学镀膜膜厚监控的精确性和自动化,为传统光学镀膜设备的升级改造提出了一种可行性技术。     

反应溅射法制备氮化铝薄膜及工作气压对其场发射性能的影响

采用反应磁控溅射法在不同工作气压(0.5～2.0Pa)下沉积了一系列氮化铝(AlN)薄膜。研究发现,在保持其他工艺参数不变的条件下,工作气压对薄膜厚度的影响很小。场发射性能测试表明,在较低的工作气压(0.5Pa和0.7Pa)下制备的AlN薄膜具有一定的场发射性能。扫描电子显微镜(SEM)图像显示,在较高的工作气压(2.0Pa)下制备的薄膜易产生空位及微空洞等缺陷,使薄膜致密性下降。电子在薄膜中的输运因受到缺陷的散射而不能隧穿表面势垒进行发射。研究表明,为获得具有良好场发射性能的AlN薄膜,若采用反应磁控溅射法,应选取较低的工作气压;同时,对于薄膜型阴极,具有紧密晶粒结构及较小缺陷的薄膜可能具有更优异的场发射性能。