Imaging with neutral atoms—a new matter-wave microscope

Matter‐wave microscopy can be dated back to 1932 when Max Knoll and Ernst Ruska published the first image obtained with a beam of focussed electrons. In this paper a new step in the development of matter‐wave microscopy is presented. We have created an instrument where a focussed beam of neutral, ground‐state atoms (helium) is used to image a sample. We present the first 2D images obtained using this new technique. The imaged sample is a free‐standing hexagonal copper grating (with a period of about 36 μm and rod thickness of about 8 μm). The images were obtained in transmission mode by scanning the focussed beam, which had a minimum spot size of about 2.0 μm in diameter (full width at half maximum) across the sample. The smallest focus achieved was 1.9 ± 0.1 μm. The resolution for this experiment was limited by the speed ratio of the atomic beam through the chromatic aberrations of the zone plate that was used to focus. Ultimately the theoretical resolution limit is set by the wavelength of the probing particle. In praxis, the resolution is limited by the source and the focussing optics.     

1H-NMR study of bovine myoglobin autoxidation. Influence of muscle type and time post mortem

¹H NMR spectroscopy was used to determine first order rate constants at four temperatures (300, 304, 308, 312 K) and activation energies of the autoxidation reaction for oxymyoglobin. the haeminic pigment was purified from two bovine muscles with different colour stabilities ( psoas major (PM) and longissimus lumborum (LL)) at 2h (day 0) and 192 h (day 8) post mortem. to characterize this autoxidation reaction, we have focused attention on the time-temperature dependent disappearance of the Val-E11 methyl group signal. This study showed that, whatever the time post mortem , although the myoglobin autoxidation rate was greater for PM than for LL muscle, the activation energies were similar. It was also worth noting that, in the range 300–312 K, the average ratio of autoxidation rate constants between day 8 and day 0 was near 1.6 for the two muscles studied. It is reasonable to think that oxidative processes developed during 8 days meat storage have led to a structural change within the cavity of the heme pocket of the myoglobins. Moreover, only one orientation of the porphyrin within the heme pocket was noted for the two muscles studied.     

Preparation of TEM samples of metal–oxide interface by the focused ion beam technique

This paper describes a procedure to prepare metal–oxide interfaces for transmission electron microscopy by the focused ion beam technique. The advantage of this procedure is to allow the observation of metal–oxide interfaces of irradiated samples with a homogeneous thickness without the need to have an instrument inside laboratories that are specialized for the manipulation of irradiated materials. A transmission electron microscopy sample is prepared by this method and analysed.     

MOMS-02/D2: First results and future applications

The Modular Opto-electronic Multi-spectral Stereo Scanner MOMS-02 experimental data acquired during the German Spacelab D2 mission will be used for a broad range of geoscientific objectives. The simultaneous acquisition of high spatial resolution, multi-spectral and stereo scenic data enables a real combination of thematic and topographic information, thus considerably improving the verification and interpretation of dynamic changes of the Earth's surface by means of remote sensing.

This paper gives a first assessment of the MOMS-02/D2 mission, the data quality and an overview on the planned methodological and application-oriented investigations for various test sites. On the basis of a few examples the possibilities of this system for future thematic applications is shown.     

硅钨酸掺杂聚苯胺催化合成2-异丙基-1,3-二氧环戊烷

采用回流法自制了硅钨酸(H4SiW12O40)掺杂聚苯胺(PAn)催化剂H4SiW12O40/PAn。通过异丁醛和乙二醇为原料合成标题化合物,探讨了硅钨酸掺杂聚苯胺催化剂对缩醛反应的催化活性,较系统地研究了原料物质的量比、催化剂用量、反应时间诸因素对产率的影响。实验表明,硅钨酸掺杂聚苯胺催化剂是合成标题化合物的良好催化剂,在n(乙二醇)∶n(异丁醛)=1.5∶1,催化剂用量为反应物料总质量的1.2%,环己烷为带水剂,反应时间1.0h的优化条件下,标题化合物的收率可达88.8%。     

Spatial and radiometric resolution of the Landsat-3 RBV system

Abstract

Major constraints on the RBV system spatial and radiometric resolution are the optical limitations of the camera lens, the sensitivity of the vidicon, the system noise and the video sampling rate. The Landsat-3 RBV lens resolution limit is 21.45 m ground equivalent half-cycle. The Earthnet video sampling rate at 7.5 megasamples, gives an across track ground pixel size of 18 m. The along track pixel size is controlled by the number of scan lines in one frame (i.e. 4125), which gives a ground equivalent pixel size of 24 m. The MTF curve calculated from the RCA manual shows an EIFOV of 45.5 m. At 21.45 m ground equivalent half-cycle, the modulation transfer factor is 5.4 per cent which with a dynamic range of 64 quantizing levels gives a two or three level contrast between black and white linear ground targets (i.e. at the extremes of the dynamic range). In the panchromatic waveband with a white level saturation at 2.013 mW/cm²-sr, most ground cover types will occur within the first 50 per cent of the dynamic range. Given the Earthnet quantization step size to r.m.s. noise ratio of 0.51, there is a 56 per cent probability of assigning a level to within ± 1 value of its correct level. This is assuming a Gaussian distribution for the system noise. The noise is equivalent to the MTF sensitivity of the system at the lens resolution limit. In this study no attempt has been made to quantify the additional noise introduced by the radiometric defects observed in the RBV data or atmospheric attenuation.