苯乙烯本体聚合反应的动态光散射研究

首次用动态光散射方法跟踪了苯乙烯本体聚合全过程的光子丁关光谱，研究了散射哟度、聚合物平移扩散和、分子量分布随聚合反应的，获得了有关聚合系和活性分子链物理状态的信息，如玻璃态的微观非均一性及活性分子链比较刚硬等。     

ELECTRO-OPTICAL DETERMINATION OF α-FeOOH PARTICLE SIZES

Electric light scattering method is used for revealing the presence of aggregates in very diluted aqueous α-FeOOH suspensions. Three theoretical models are used for the geometrical form of aggregates. The comparison between the electro-optical results -theoretical and experimental - shows that even in the most diluted suspensions exist aggregates with irregular form. Using the comparison between electron microscopy and electro-optical results the geometric shape of the aggregates is determined.     

基于过程分析技术和设计空间的金银花醇沉加醇过程终点检测

建立了一种新的基于过程分析技术(PAT)和质量源于设计(QbD)设计空间的中药制药过程终点分析与控制方法.以近红外(NIR)光谱技术为PAT工具, 采集正常操作条件下制药过程的多批次NIR光谱; 采用主成分分析结合移动块相对标准偏差(PCA-MBRSD)法, 确定每一批次过程的理想终点样本(DEPs), 由多批DEPs的光谱信息构成过程终点设计空间; 在过程终点设计空间确定的范围内, 建立多变量统计过程控制(MSPC)模型, 利用多变量Hotelling T²和SPE控制图对过程终点进行判断.应用上述方法, 进行了金银花醇沉加醇过程终点检测研究, 结果表明该方法灵敏、准确, 适宜于中药制药过程终点检测.     

Calibration transfer strategy to compensate for instrumental drift in portable quadrupole mass spectrometers

We report the use of a calibration transfer strategy to correct for drift in the quantitative sensitivity of a portable quadrupole mass spectrometer (QMS) aimed at process monitoring applications. Gas mixtures of CH₄/Ar/C₂H₆/CO₂ were studied with calibration phase measurements made of the pure gases for a univariate analysis and of 40 multi-component mixtures for a multivariate approach. To evaluate calibrations, test set spectra of a CH₄/Ar/C₂H₆/CO₂ gas mixture were recorded bi-weekly over a period of 12 months. As part of the strategy a standard of pure argon was measured during both calibration and test phases so that correction factors could be calculated for each measurement day. It was shown that in the absence of a calibration transfer strategy quantifications of test set spectra could be inaccurate by more than an order of magnitude over 12 months. Furthermore, due to the effects of drift in the sensitivity over the 6 days required to record the training set in the calibration phase it was found that the multivariate analysis quantified test spectra less accurately than the univariate analysis. However, by applying the calibration transfer strategy across all measurements (both calibration and test phases) it was shown that the errors in prediction using the multivariate analysis previously seen after 2 weeks were not observed until approximately 12 months later.     

Optimising reaction performance in the pharmaceutical industry by monitoring with NMR

Quality assurance and process understanding are assuming increasing importance in the production of Active Pharmaceutical Ingredients (APIs). NMR has the potential to report on physical processes, quantities, structures, and speciation as chemical reactions progress. Following the progression of chemical reactions by placing the sample in an NMR tube, one can perform a large number of useful studies that provide chemical and mechanistic insight. But this simple approach can have limitations, and we have therefore constructed an apparatus comprising a laboratory reactor coupled with an NMR flow cell. The reactor duplicates the exact reaction conditions that will apply with large-scale production. This reaction mixture is sampled and pumped to a high-resolution NMR flow cell where the spectrum is recorded through the course of the reaction. We demonstrate the utility of reaction monitoring using NMR both for simple cases where tubes can be used, and describe the design of the on-flow apparatus and highlight its utility with an example.     

Real-time assessment of carbon nanotube alignment in a polymer matrix under an applied electric field via polarized Raman spectroscopy

A technique has been developed utilizing polarized Raman spectroscopy to measure alignment of carbon nanotubes in situ in a polymer matrix under an applied electric field. Previous studies of alignment have been restricted to optically transparent solvents or polymerized specimens that prevent accurate analyses of alignment dynamics in polymers. The effects of electric field strength on the degree of alignment and the time to achieve an aligned state are discussed. The use of in situ, real-time polarized Raman spectroscopy provides a non-invasive technique for assessing carbon nanotube alignment, which can assist in determining processing conditions to improve the mechanical and electrical properties of aligned nanocomposites.     

Monitoring the manufacturing process of glass fiber reinforced composites with carbon nanotube buckypaper sensor

Buckypapers are free-standing porous mats of entangled CNT ropes cohesively bounded by van der waals interactions, and can be used to monitor the manufacturing process of glass fiber reinforced composite. In this paper, the buckypaper (BP) was fabricated with monodispersion of multi-wall carbon nanotubes via spray-vacuum filtration, and its morphology and pore size distribution were characterized by scanning electron microscope and nitrogen adsorption/desorption. The resistance of the BP sensor was obtained using a four-point probe method, and the resistance changes could be related to phase changes of the resin matrix,. Experimental results show that the BP sensor embedded in the glass/epoxy composite laminates has indicated a relative resistance change from −2.9% to 226.5% during the manufacturing process. In addition, the temperature sensitivity of a pristine BP sensor and a BP sensor embedded in composite were also characterized. The results demonstrate that the effect of resin phase changes on the resistance changes of a BP sensor is greater than that of the temperature during composite manufacturing.     

GaAs(100)解理面的能带弯曲

在真空中解理后,用XPS测得了GaAs样品（110）断面能带弯曲的动态过程．两组重掺杂n型和p型GaAs样品的费米能级分别向禁带中间的方向移动了0.4eV和0．3eV.实验测得重掺杂n型和p型GaAs样品费米能级之差为1．3eV,它们的禁带宽度理论值为1．42eV,这说明结果是合理的．根据实验结果,对引起GaAs表面能带弯曲的可能原因进行了分析讨论．排除了本征表面态、真空中残留气体和X射线辐射等原因,认为解理过程在表面产生的缺陷和解理后表面晶格弛豫过程中产生的缺陷可能是导致能带弯曲的主要原因．