Word绘图功能在物理实验教学活动中的应用

本介绍Wierosoft公司Office组件Word的绘图功能在物理实验方面的应用。在掌握Word绘图基本的方法及技巧后。能胜任物理实验教学实践活动中的作图要求。     

Influence of weakly bound adduct ions on breath trace gas analysis by selected ion flow tube mass spectrometry (SIFT-MS)

This paper describes how weakly bound adduct ions form when the precursor ions used in selected ion flow mass spectrometry, SIFT-MS, analyses, viz. H₃O⁺, NO⁺ and O₂⁺, associate with the major components of air and exhaled breath, N₂, O₂ and CO₂. These adduct ions, which include H₃O⁺N₂, H₃O⁺CO₂, NO⁺CO₂, O₂⁺O₂ and O₂⁺CO₂, are clearly seen when dry air containing 5% CO₂ (typical of that in exhaled breath) is analysed using SIFT-MS. These adduct ions must not be misinterpreted as characteristic product ions of trace gases; if so, serious analytical errors can result. However, when exhaled breath is analysed these adduct ions are partly removed by ligand switching reactions with the abundant water molecules and the problems they represent are alleviated. But the small fractions of the adduct ions that remain in the SIFT-MS spectra, and especially when they are isobaric with genuine characteristic product ion of breath trace gases, can result in erroneous quantifications; such is the case for H₃O⁺N₂ interfering with breath ethanol analysis and H₃O⁺CO₂ with breath acetaldehyde analysis. However, these difficulties can be overcome when the isobaric adduct ions are properly recognised and excluded from the analyses; then these two important compounds can be properly quantified in breath. The presence of O₂⁺CO₂ in the product ion spectra interferes with the analysis of CS₂ present at low levels in exhaled breath. It is likely that similar problems will occur as other trace compounds are detected in exhaled breath when consideration will have to be given to the possibility of overlapping between their characteristic product ions and ions produced by hitherto unknown reactions. Similar problems are evident in other systems; for example, H₃O⁺CH₄ adduct ions are observed in both SIFT-MS analyses of methane rich mixtures like biologically generated waste gases and in model planetary atmospheres.     

Estimating the measurement uncertainty in forensic breath-alcohol analysis

The evidentiary weight attributed to forensic breath alcohol results in drunk-driving prosecutions requires that measurement uncertainty be established and shown to be fit-for-purpose. The principal components contributing to breath alcohol measurement uncertainty include: (1) biological/sampling, (2) instrumental, (3) traceability and (4) the water/air partition coefficient for control standards. Employing duplicate breath results from over 92,000 subjects to estimate the biological/sampling component and assuming reasonable forensic values for the other components, the combined and expanded uncertainty is determined for a practical example. The combined uncertainty for an unbiased single determination breath alcohol measurement was: . Employing the expanded uncertainty (k = 2.58), the 99% confidence interval for a mean breath alcohol concentration of 0.0935 g/210 L was 0.0866 to 0.1004 g/210 L. The proportion of combined uncertainty associated with each component was determined to be: biological/sampling 73%, analytical 10%, traceability 13% and water/air partition coefficient 4%. These are forensically acceptable estimates and demonstrate fitness-for-purpose of breath alcohol measurement when employing appropriate elements of quality control.     

Temperature-modulated differential scanning calorimetry of reversible and irreversible first-order transitions

Temperature-modulated differential scanning calorimetry of first-order transitions has led to many new observations. Some of these involve non-linear processes or deal with transformations of practically instantaneous response. The latter may cause serious lags within the calorimeter due to limited thermal conductivity of the sample and the instrument. In both cases the “reversing heat capacity” or a “complex heat capacity” is not a precise representation of the transition since both are computed from abbreviated Fourier transforms, limited to the evaluation of the first harmonic component. One has in these cases to work in the time-domain with the raw output. But even from these analyses in the time-domain many interesting new insights about the transition and the calorimeter performance can be generated.     

呼气中挥发性硫化物的质子转移反应质谱在线检测

利用自主研制的高灵敏呼气检测质子转移反应质谱(PTR-MS),对一名口臭受试者的口腔吹出气体、鼻子呼出气体和口腔内气体分别进行多组分实时监测,发现了该受试者呼气中3种引起口臭的挥发性硫化物(VSCs)的来源并不相同,其中甲硫醇主要来源于口腔,硫化氢和二甲基硫则主要来源于肺或呼吸道.本研究不仅发现了口腔内气体在PTR-MS呼气监测过程中的特征变化趋势,还分析了呼出气体中3种VSCs的来源,对于呼气的正确采样和检测具有重要的指导意义.     

Investigation of orientation relationships by EBSD and EDS on the example of the Watson iron meteorite

The suitability of the electron back‐scatter diffraction technique (supported by EDS) in order to study the complex microstructures of iron meteorites is demonstrated on the example of the Watson meteorite. The orientation relationships between the main phases kamacite, taenite and schreibersite/rhabdite as well as effects of the real structure have been investigated. In kamacite bands highly deformed blocks appear which show a contineous change of orientation. Plessitic regions are surrounded by deformed taenite lamellae. Also these lamellae show the typical M‐profile of the Ni concentration in cross section. In the center a martensitic microstructure has been proven. The white plessite is characterized by a high number of individual kamacite grains which however are separated mainly by low‐angle boundaries. So an orientation clustering occurs. The determination of orientation relationships was only possible for a single plessite region comparing the intensity distribution in pole figures with simulations. Schreibersite is brittle and shows a high number of microcracks. However, the strong deformation of kamacite does not allow us to decide whether an orientation relationship between the phosphides and the surrounding kamacite exists or not. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Instructions to Authors

正Submission Papers appearing in the Journal comprise Regular Articles,Notes,Rapid Communications,which should contain original information,theoretical or experimental,on any topics in the field of polymer science and polymer material science.Feature Articles are also welcome.Papers already published or scheduled to be published elsewhere will not be accepted.Notes and Rapid Communications     

Ultrasensitive Organic Humidity Sensor with High Specificity for Healthcare Applications

Humidity sensors have gained immense importance as non‐invasive, wearable healthcare devices for personal care as well as disease diagnostics. However, non‐specificity, poor stability at extreme conditions, and low sensitivity of the humidity sensor inhibit its usage as a health monitoring device. In the present study, N?F containing organic molecule, Selectfluor^TM (F‐TEDA) based humidity sensors with ～1–2 mm long needle‐shaped crystals is fabricated on interdigitated electrodes resulting in excellent performance. The unidirectional growth of crystals led to the formation of a conduction pathway for water molecules across the crystal, which otherwise are non‐conducting. The as‐fabricated humidity sensor at an operational voltage of 0.8 V displays a sensitivity of six orders in magnitude, best reported so far. The sensor does not exhibit any response upon exposure to various volatile organic compounds and reactive gases, indicating remarkable specificity. The sensor is tolerant to high moisture of 95 % for prolonged hours followed by monitoring over several days and degrades to 50 % of its original sensitivity only after continuous exposure for several days. Electrochemical impedance spectroscopy (EIS) shows reversal from resistive to capacitive behavior with increasing humidity levels. The fabricated humidity sensor acts as a healthcare device for breath rate monitoring and touch‐free examination of skin moisture.     

A new and consistent parameter for measuring the quality of multivariate analytical methods: Generalized analytical sensitivity

Generalized analytical sensitivity (γ) is proposed as a new figure of merit, which can be estimated from a multivariate calibration data set. It can be confidently applied to compare different calibration methodologies, and helps to solve literature inconsistencies on the relationship between classical sensitivity and prediction error. In contrast to the classical plain sensitivity, γ incorporates the noise properties in its definition, and its inverse is well correlated with root mean square errors of prediction in the presence of general noise structures. The proposal is supported by studying simulated and experimental first-order multivariate calibration systems with various models, namely multiple linear regression, principal component regression (PCR) and maximum likelihood PCR (MLPCR). The simulations included instrumental noise of different types: independently and identically distributed (iid), correlated (pink) and proportional noise, while the experimental data carried noise which is clearly non-iid.     

An Aggregation‐Induced‐Emission Platform for Direct Visualization of Interfacial Dynamic Self‐Assembly

An in‐depth understanding of dynamic interfacial self‐assembly processes is essential for a wide range of topics in theoretical physics, materials design, and biomedical research. However, direct monitoring of such processes is hampered by the poor imaging contrast of a thin interfacial layer. We report in situ imaging technology capable of selectively highlighting self‐assembly at the phase boundary in real time by employing the unique photophysical properties of aggregation‐induced emission. Its application to the study of breath‐figure formation, an immensely useful yet poorly understood phenomenon, provided a mechanistic model supported by direct visualization of all main steps and fully corroborated by simulation and theoretical analysis. This platform is expected to advance the understanding of the dynamic phase‐transition phenomena, offer insights into interfacial biological processes, and guide development of novel self‐assembly technologies.