Cryo—Cracking方法及其在焊接接头蠕变断裂失效分析中的应用

介绍了Cryo-Cracking方法及其在分析和评定高温下和长期服役的焊管焊接接头蠕变失效中的应用特点,这种方法使用的试样易于截取,制样工艺过程简单,对制样者的技艺无特殊要求,不易产生因试样的制备而引起的误解,通过扫描电镜断口形貌的分析,结合金相定量分析方法,从分析断口的二维图象获得的数据,可以定量地反映在役构件蠕变失效的程度。实践表明,Cryo-Cracking方法是一种简单实用的焊接接头蠕变失效分析方法。     

Low temperature techniques for X-ray microanalysis in pathology: Alternatives to cryoultramicrotomy

Many diseases are associated with a change in the distribution of diffusible ions at the cell or tissue level. These diseases can profitably be studied by X-ray microanalysis. This technique for the study of ion distribution requires the use of cryoprepared specimens. Analysis at low or medium resolution can be carried out on thick or semi-thick cryosections, or on frozenhydrated or freeze-dried embedded bulk samples. Such analyses are particularly useful in the initial stages of an investigation or when data from a large number of samples have to be acquired. Also X-ray microanalysis of cultured or single cells prepared by freeze-drying can be used to rapidly collect information on a large number of cells. Analysis at high resolution has to be carried out on thin sections: Cryosections or sections of freeze-substituted or freeze-dried embedded tissue. For the latter type of specimens, the use of low-temperature embedding methods may have important advantages.     

A technique for improved focused ion beam milling of cryo-prepared life science specimens

The combination of focused ion beam and scanning electron microscopy with a cryo‐preparation/transfer system allows specimens to be milled at low temperatures. However, for biological specimens in particular, the quality of results is strongly dependent on correct preparation of the specimen surface. We demonstrate a method for deposition of a protective, planarizing surface layer onto a cryo‐sample, enabling high‐quality cross‐sectioning using the ion beam and investigation of structures at the nanoscale.     

Soft X-ray microscopy with a cryo scanning transmission X-ray microscope: I. Instrumentation, imaging and spectroscopy

We have developed a cryo scanning transmission X-ray microscope which uses soft X-rays from the National Synchrotron Light Source. The system is capable of imaging frozen hydrated specimens with a thickness of up to 10 μm at temperatures of around 100 K. We show images and spectra from frozen hydrated eukaryotic cells, and a demonstration that biological specimens do not suffer mass loss or morphological changes at radiation doses up to about 10¹⁰ Gray. This makes possible studies where multiple images of the same specimen area are needed, such as tomography ( Wang et al. (2000 ) Soft X-ray microscopy with a cryo scanning transmission X-ray microscope: II. Tomography. J. Microsc . 197, 80–93) or spectroscopic analysis.     

Cryo‐scanning electron microscopy investigation of the Octopus Vulgaris arm structures for the design of an octopus‐like arm artefact

Octopus vulgaris is a cephalopod of the Octopodidae family. It has four pairs of arms and two rows of suckers which perform many functions, including bending and elongation. For this reason the octopus was chosen as model to develop a new generation of soft‐body robots. In order to explain some of the fine structures of the octopus arm in relation to its specific ability, we examined the external and internal structures of O. vulgaris arms in a frozen‐hydrated state using cryo‐scanning electron microscopy. The arms showed skin with a very complex design that is useful to elongation, and a pore pattern distribution on their surface which is functional to cutaneous oxygen uptake. The analysis of freeze‐fractured frozen‐hydrated arm samples allowed us to describe the developmental differences in the relative proportion of the areas of axial nerve cord, intrinsic and extrinsic musculature, in relation to the growth of the arms and of the increase in functional capability. In the suckers, we analyzed the shedding mechanisms in the outer part of the infundibulum and described the outer and inner characteristics of the denticles, showing in detail their pore system, which is fundamental for their ability to explore the environment. These results are discussed by considering their possible application in the design of new octopus‐like artefacts, which will be able to take advantage of some of these ultrastructure characteristics and achieve advanced bioinspired functionalities. Microsc. Res. Tech. 78:1133–1145, 2015. © 2015 Wiley Periodicals, Inc.     

灌瓶厂制冷机余热回收利用实践

针对灌瓶厂低温制冷机组工作时排放大量热量,而低温灌注的饮料又需要通过暖瓶（罐）机进行升温而消耗蒸汽这一现状,为促进节能减排,某灌瓶厂于2006年率先开始尝试应用制冷机余热回收技术。实践证明：应用该项技术,平均投资回收期为5个月,每年可为企业节约能耗总费用近40万元。经过多年运行,此项技术已经得到业内广泛的认可并在诸多灌瓶厂得到广泛应用。     

Self-pressurized rapid freezing (SPRF): a novel cryofixation method for specimen preparation in electron microscopy

A method is described for the cryofixation of biological specimens for ultrastructural analysis and immunocytochemical detection studies. The method employs plunge freezing of specimens in a sealed capillary tube into a cryogen such as liquid propane or liquid nitrogen. Using this method a number of single-cell test specimens were well preserved. Also multicellular organisms, such as Caenorhabditis elegans , could be frozen adequately in low ionic strength media or even in water. The preservation of these unprotected specimens is comparable to that achieved with high-pressure freezing in the presence of cryoprotectant. The results are explained by the fact that cooling of water in a confined space below the melting point gives rise to pressure build-up, which may originate from the conversion of a fraction of the water content into low-density hexagonal ice and/or expansion of water during supercooling. Calculations indicate the pressure may be similar in magnitude to that applied in high-pressure freezing. Because the specimens are plunge cooled, suitable cryogens are not limited to liquid nitrogen. It is shown that a range of cryogens and cryogen temperatures can be used successfully. Because the pressure is generated inside the specimen holders as a result of the cooling rather than applied from an external source as in high-pressure freezing, the technique has been referred to as self-pressurized rapid freezing.     

Cryo-EM--the first thirty years

Thirty years ago, in December 1981, The Journal of Microscopy published a very short paper entitled ‘Vitrification of pure water for electron microscopy’. It turned out to be important for the development of cryo-electron microscopy and it contributed to reverse, from foe to friend, the status of water in electron microscopists’ minds. This change has brought obvious gains. The future will tell how many more are still to come.     

Thinning of large mammalian cells for cryo-TEM characterization by cryo-FIB milling

Focused ion beam milling at cryogenic temperatures (cryo-FIB) is a valuable tool that can be used to thin vitreous biological specimens for subsequent imaging and analysis by cryo-transmission electron microscopy (cryo-TEM) in a frozen-hydrated state. This technique offers the potential benefit of eliminating the mechanical artefacts that are typically found with cryo-ultramicrotomy. However, due to the additional complexity in transferring samples in and out of the FIB, contamination and devitrification of the amorphous ice is commonly encountered. To address these problems, we have designed a sample cryo-shuttle that directly and specifically accepts Polara TEM cartridges to simplify the transfer process between FIB and TEM. We optimized several parameters in the cryo-FIB and cryo-TEM processes using the quality of the samples' ice as an indicator and demonstrated high-quality milling with large mammalian cells. By comparing the results from HeLa cells to those from Escherichia coli cells, we discuss some of the artefacts and challenges we have encountered using this technique.     

Roll-formability of cryo-rolled ultrafine aluminium sheet

Ultrafine-grain aluminium sheet was produced by rolling at cryogenic (CR) and at room temperature (RTR). Commercial purity aluminium plate was reduced in 30 passes from an initial material thickness of 10 mm to a final thickness of 2 mm (80% reduction). Tensile stress and strength were significantly increased while total elongation was drastically reduced. It was found that despite the low tensile elongation both materials are able to accommodate high localised strains in the neck leading to a high reduction in area. The formability of the material was further investigated in bending operations. A minimum bending radius of 6 mm (CR) and 5 mm (RTR) was found and pure bending tests showed homogeneous forming behaviour for both materials. In V-die bending the cryo-rolled material showed strain localisations across the final radius and kinking of the sample. It has been found that even if the total elongation in tension is close to zero leading to early failure in V-die bending, ultra-fine grained and low ductile sheet metals can be roll formed to simple section shapes with small radii using commercial roll forming equipment.