阳极键合应力的原位拉曼光谱研究

介绍了一种基于原位激光拉曼光谱的阳极键合应力研究方法。通过自制的小型阳极键合装置,结合激光拉曼光谱仪,原位研究了在阳极键合升温、通电和降温过程中硅界面应力的演变过程。升温过程中单晶硅的拉曼峰位会向低波数移动,通电恒温键合过程中氧化硅的生长会在单晶硅界面引入拉应力,降温过程中单晶硅界面的应力状态发生从拉应力到压应力的转变。界面的氧化过程对阳极键合结构界面的应力状态有重要影响。     

生物医学拉曼光谱质控方法研究

目的评价生物医学拉曼光谱设备的关键性能参数,为开展不同厂家产品的一致性比对和建立拉曼光谱类医疗器械的检测规范做准备。方法开发通用的拉曼光谱实验平台,测量化学参考物质,开发光谱分析方法,对实验系统的分辨率、波长校正、信噪比、系统响应等进行分析,并使用几种常见的生物分子进行测试验证。结果根据化学参考物质的拉曼光谱提取了实验系统的光谱分辨率、波长校正、信噪比、系统响应等信息,在测试中可有效地将生物分子的原始拉曼谱还原为可比对的标准拉曼谱。结论本文方法可有效提取和评价拉曼系统的性能参数,这对于拉曼光谱和其他相关光谱医疗器械的质控具有积极意义。     

Spectroscopic probe to contribution of physicochemical transformations in the toxicity of aged ZnO NPs to Chlorella vulgaris: new insight into the variation of toxicity of ZnO NPs under aging process

Zinc oxide nanoparticles (ZnO NPs) are one of the most abundantly applied nanomaterials in nanotechnology-based industries and they may cause unexpected environmental and health risks with their physicochemical transformations in the environment. Currently, there is still a lack of the in-depth understanding of the toxicity of aged ZnO NPs to aquatic organisms, particularly demanding quantitative analysis of the physicochemical transformations to distinguish their contributions in the toxicity assessment. For this purpose, therefore, we initiated the study of the toxicity of aged ZnO NPs to the model aquatic microalga, i.e. Chlorella vulgaris, and with the aid of spectroscopic tools for characterization and quantification of the physicochemical transformations, we scrutinized the toxicity variations for ZnO NPs with different aging times. As a result, we found that the toxicity altered in an abnormal manner with the aging time, i.e. the toxicity of aged ZnO NPs for 30 days showed the higher toxicity to the green alga than the fresh ZnO NPs or the ZnO NPs aged for longer time (e.g. 120 and 210 days). Through spectroscopic tools such as XRD, FTIR and Raman spectroscopy, we made both the qualitative and quantitative assessments of the physicochemical changes of the ZnO NPs, and confirmed that in the early stage, the toxicity mainly stemmed from the release of zinc ions, but with longer aging time, the neoformation of the nanoparticles played the critical role, leading to the overall reduced toxicity due to the less toxic hydrozincite and zinc hydroxide in the transformed compounds.     

Optical diagnosis of gastric cancer using near-infrared multichannel Raman spectroscopy with a 1064-nm excitation wavelength

Background Gastric cancer is one of the most common cancers in Japan. The use of endoscopy is increasing, along with the number of histological examinations of specimens obtained by endoscopy. However, it takes several days to reach a diagnosis, which increases the medical expense. Raman spectroscopy is one of the available optical techniques, and the Raman spectrum for each molecule and tissue is characteristic and specific. The present study investigated whether Raman spectroscopy can be used to diagnose gastric cancer. Methods A total of 251 fresh biopsy specimens of gastric carcinoma and non-neoplastic mucosa were obtained from 49 gastric cancer patients at endoscopy. Without any pretreatment, the fresh specimens were measured with a near-infrared multichannel Raman spectroscopic system with an excitation wavelength of 1064 nm, and Raman spectra specific for the specimens were obtained. A principal component analysis (PCA) was performed to distinguish gastric cancer and non-neoplastic tissue, and a discriminant analysis was used to evaluate the accuracy of the gastric cancer diagnosis. Results The Raman spectra for cancer specimens differed from those for non-neoplastic specimens, especially at around 1644 cm⁻¹. Sensitivity was 66%, specificity was 73%, and accuracy was 70%. The accuracy of diagnosis using the single Raman scattering intensity at 1644 cm⁻¹ was 70%, consistent with the PCA result. Conclusions The present results indicate that near-infrared multichannel Raman spectroscopy with a 1064-nm excitation wavelength is useful for gastric cancer diagnosis. Establishment of a Raman diagnostic system for gastric cancer may improve the clinical diagnosis of gastric cancer and be beneficial for patients.     

Inelastic x-ray scattering of dense solid oxygen: evidence for intermolecular bonding

The detailing of the intermolecular interactions in dense solid oxygen is essential for an understanding of the rich polymorphism and remarkable properties of this element at high pressure. Synchrotron inelastic x-ray scattering measurements of oxygen K-edge excitations to 38 GPa reveal changes in electronic structure and bonding on compression of the molecular solid. The measurements show that O₂ molecules interact predominantly through the half-filled 1π_g* orbital <10 GPa. Enhanced intermolecular interactions develop because of increasing overlap of the 1π_g* orbital in the low-pressure phases, leading to electron delocalization and ultimately intermolecular bonding between O₂ molecules at the transition to the ε-phase. The ε-phase, which consists of (O₂)₄ clusters, displays the bonding characteristics of a closed-shell system. Increasing interactions between (O₂)₄ clusters develop upon compression of the ε-phase, and provide a potential mechanism for intercluster bonding in still higher-pressure phases.     

Resonance Raman and temperature-dependent electronic absorption spectra of cavity and noncavity models of the hydrated electron

Most of what is known about the structure of the hydrated electron comes from mixed quantum/classical simulations, which depend on the pseudopotential that couples the quantum electron to the classical water molecules. These potentials usually are highly repulsive, producing cavity-bound hydrated electrons that break the local water H-bonding structure. However, we recently developed a more attractive potential, which produces a hydrated electron that encompasses a region of enhanced water density. Both our noncavity and the various cavity models predict similar experimental observables. In this paper, we work to distinguish between these models by studying both the temperature dependence of the optical absorption spectrum, which provides insight into the balance of the attractive and repulsive terms in the potential, and the resonance Raman spectrum, which provides a direct measure of the local H-bonding environment near the electron. We find that only our noncavity model can capture the experimental red shift of the hydrated electron’s absorption spectrum with increasing temperature at constant density. Cavity models of the hydrated electron predict a solvation structure similar to that of the larger aqueous halides, leading to a Raman O–H stretching band that is blue-shifted and narrower than that of bulk water. In contrast, experiments show the hydrated electron has a broader and red-shifted O–H stretching band compared with bulk water, a feature recovered by our noncavity model. We conclude that although our noncavity model does not provide perfect quantitative agreement with experiment, the hydrated electron must have a significant degree of noncavity character.