Volume 33(1) - Winter 2017

TG-DTA is a thermal analysis technique that measures the weight change of a sample (thermogravimetry, TG), and endothermic and exothermic reactions based on the difference in temperature between the sample and a reference (differential thermal analysis, DTA) during a programmed temperature change. It can measure the weight changes associated with dehydration or decomposition, and the temperatures of endo/exothermic reactions such as melting and transition. TG 8121 with sample observation attachment, a new entry in the Thermo plus EVO2 series, allows visual observation of the sample by a CCD camera mounted directly above the specimen while performing conventional TG-DTA measurements.

Riding on the success of the XtaLAB mini as a compact, low-maintenance, benchtop system providing high-quality crystal structures, the new XtaLAB mini II has been developed. The XtaLAB mini II differs to its predecessor by the inclusion of a Hybrid Photon Counting (HPC) detector, called the HyPix-Bantam. HPC detectors are at the cutting edge of diffraction technology, and are widely used at synchrotron beamlines due to their high sensitivity and fast read-out speeds. The whole system is controlled by the popular CrysAlis^Pro software, which offers users the ability to complete their structure determination with one software package.

We have discussed about the feature of X-ray fluorescence analysis (XRF) which is quick and nondestructive analysis of liquid, solid and powder sample in the previous issues. In this paper, analysis examples of liquid samples are shown. Careful attention is required for handling of liquid sample, because there are many kinds of liquids such as water solution, organic solvent, oil, etc., and each one has various kinds of properties such as acid, alkaline, etc. In this issue, analysis method for liquid samples by wavelength dispersive X-ray fluorescence analysis spectrometer (WDX) is discussed.

The principle problem in single crystal X-ray analysis is the so-called “phase problem”; however, in the current situation in which various measurement devices, synchrotron radiation facilities and sophisticated software have become available, the largest bottleneck in practice is the acquisition of single crystals, that is, crystallization of the substance to be analyzed. Crystallization is particularly difficult for biomacromolecules. For ribosome, the largest asymmetric single molecule analyzed to date, acquisition of crystals yielding low-resolution diffraction was first reported in 1980, but crystals diffracting to a practical resolution could not be obtained for more than two decades. One of the reasons that it took so long was that only a limited number of researchers had addressed this challenge, as ribosome crystallization had been initially considered an unfeasible task. This was because ribosome was believed to have multiple subtypes and was thus low in homogeneity. If the homogeneity could be evaluated before crystallization, more researchers might have attempted ribosome crystallization to achieve successful ribosome crystallization a few years earlier. This article describes small-angle X-ray scattering from solution-state protein samples and its relevance to evaluation of protein crystallizability.

A parabolic multilayer mirror as an X-ray optical device has been applied to general-purpose X-ray diffractometers since the 1990s. X-rays formed by such a device are of high brightness, of small divergence and adequately monochromated. This device enables us to use high-quality parallel X-rays even in laboratories. Also, this device makes channel-cut 2-bounce beam-conditioner optics more effective, and various measurement techniques for a variety of samples, either powder materials or thin films, are more easily performed with general-purpose X-ray diffractometers. On the other hand, the most popular optic for powder X-ray diffraction is a conventional Bragg–Brentano para-focusing optic (BB optic), due to ease of setup, high intensity, and high angular resolution. Therefore, general-purpose X-ray diffractometers can be more effectively used if both of these optics, parallel beam (PB) optic and BB optic, can be switched easily.

Rigaku has developed and patented a CBO (Cross Beam Optics) unit that can switch a BB optic and a PB optic using a parabolic multilayer mirror by simply changing the selection slit. Subsequently, the “CBO-E” unit, which has a multilayer mirror forming a convergent beam, was marketed to accommodate diverse measurement needs. In recent years, the “CBO-α” unit, which creates a divergent beam, has been also developed.

In this report, we introduce the features and applications of each member of the CBO unit series to help SmartLab users achieve effective X-ray diffraction measurements and high-quality data acquisitions for precise analyses.

Epitaxial thin films are widely studied in the interest of fundamental scientific research into the physical properties of materials, but also due to the emerging demands of high efficiency in a wide range of industrial applications.

Among the most famous epitaxial thin films are GaN films for LED applications, the development of which led to the awarding of the Nobel Prize in Physics in 2014. The GaN heteroepitaxial films for these LEDs were grown on sapphire substrates after overcoming the large lattice mismatch between them. Though a symmetric similarity for c-axis growth of GaN (hexagonal) on the c-plane of sapphire (trigonal) exists, these two materials are totally different in the crystallographical sense. Complex domain structures and large mosaic spread (tilt/twist) of GaN epitaxial films were caused mainly by the large lattice mismatches.

In the pursuit of new characteristics comparable to GaN-LEDs, recent studies have concentrated on growing functional thin films epitaxially crystallographically different substrates. In this process, XRD analysis will be very helpful to characterize their orientation relationships, crystalline quality, etc.

It is well known that X-rays can penetrate opaque objects and show the internal structure without destroying the object. Thus, X-rays are widely used for medical imaging, security and industrial inspection to name a few examples. In addition, X-ray computed tomography (CT) is a powerful technique for visualizing internal structure of various specimens including the human body, in three dimensions (3D). Recently, a high spatial resolution X-ray microscope has been developed as a result of improvements in microfocus X-ray sources and high resolution X-ray detectors, making it possible to determine the precise internal 3D structure at micrometer resolution. Rigaku has developed a unique 3D X-ray microscope, the nano3DX, by the application of the quasi-parallel beam technique with a rotating anode high-power X-ray source and submicron-resolution X-ray detector. An additional feature of the nano3DX is that it provides the ability to obtain high-contrast CT images for low-Z materials utilizing relatively low energy X-rays, e.g., Cu or Mo characteristic radiation. This feature of the nano3DX makes it very well suited for structural studies and/or inspection of various low-Z materials, e.g., polymer composite, pharmaceutical tablets, biomaterials and foods. Conventional X-ray microscopes use high energy tungsten white radiation to probe the specimen. The high energy X-rays make it difficult to distinguish constituent low-Z components from each other due to their low absorption. In addition, there is also demand for precise investigation of structural changes induced by changes in environmental conditions, for example, temperature variations or application of compression or tensile stress. In order to investigate structural changes under real environmental conditions, it was necessary to build in situ attachments, which can be combined with CT measurements.

The Nobel Prize in Physiology or Medicine was awarded to a Japanese scientist for the second year in a row for 2016. The laureate is Professor Yoshinori Osumi of the Tokyo Institute of Technology who received the award for the discovery of autophagy. Generally speaking, knowledge of autophagy is limited to researchers in biology related fields, therefore the achievement of Professor Osumi may not be understood immediately as compared to the work by Professor Satoshi Omura discovering ivermectin which prevents blindness in over 300,000 people every year.

The first observation of autophagy by Dr. Osumi occurred when budding yeast lacking a degradation enzyme contained in the vacuole were cultured in a nitrogen-free starvation medium. The key was successful observation of cytoplasmic components which are normally decomposed by vacuolar enzymes with a visible light microscope. In this genetically defected yeast, autophagy was activated in the starvation state, but recycling was suppressed because there was no enzymes for decomposing cellular waste proteins.“Auto” in autophagy means “self” in Greek