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1
Barkan, Shaul. « Si(Li) detector for microanalysis cooled by thermoelectric device ». Proceedings, annual meeting, Electron Microscopy Society of America 50, no 2 (août 1992) : 1736–37. http://dx.doi.org/10.1017/s042482010013331x.
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Cooling down solid state detecors, with other different way then liquid Nitrogen, is a goal of many vendors and customers since the invention of these detectors. THe disadvantage of the common way of liquid Nitrogen is first the inavailibility of the LN in many uses (like space military and any other applications that are not done inside a well organize Laboratory). The use of LN also considers as a Labor consumer in addition to the big dewar that has to be added to any detector for storing the LN, the boiling of the LN, may cause microphonics problesm and the refiling of the dewar in many Labs is a complicated process due to inconvenience location of the microscope.In this paper I will show a spectra result of 10mm2 SiLi detector for microanalysis use, cooled by peltier cooler. The peltier cooler has the advantage of non-microphonics and non-labor needed (like adding LN to the dewar).
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Anugu, Narsireddy, António Amorim, Paulo Garcia, Paulo Gordo, Tiago Frederico et Jorge Abreu. « A Low Cost Auto-filling and Refrigeration Rate Regulated Liquid Nitrogen Controller for Near Infrared Instruments ». U.Porto Journal of Engineering 1, no 2 (19 mars 2018) : 45–51. http://dx.doi.org/10.24840/2183-6493_001.002_0006.
Texte intégralRésumé :
Liquid Nitrogen is one of the key refrigerating elements in cooling near infrared science instruments to reduce the dark, readout noises and thermal emissions in the near infrared originated from the instrument structure. Usually, a small liquid nitrogen tank connected to the near infrared instrument is auto filled from a large Dewar in order to maintain required low temperatures during the experiment for several hours. The detectors used in these instruments are quite expensive and they need to be cooled down steadily (< 2K/min) to avoid mechanical damage. The steady state cooling of the detector is the key requirement to be considered while cooling down the detector. In this paper, a controller is developed to auto-fill the liquid nitrogen tank and also to keep the refrigeration rate of the detector below 2K/min. A systematic survey of auto-filling controllers is studied. The auto-filling of liquid nitrogen from Dewar to tank is implemented with a standard on-off controller. To address the critical refrigeration rate of the detector, two approaches are studied: a) by fixed time pumping; b) by feedback the detector cooling rate. In this work we have used inexpensive equipment to develop this controller. It is very successfully used for GRAVITY acquisition camera, a near infrared instrument for European Southern Observatory. This controller has been stable and efficient for our experiment. This low cost controller can be used for any student laboratory and research.
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Yakovlevs, O., V. Malgin et V. Gostilo. « Development of Unified Spectrometric Module Based on HPGE Detectors with Electric Machine Cooling ». Nuclear and Radiation Safety, no 3(79) (28 août 2018) : 48–55. http://dx.doi.org/10.32918/nrs.2018.3(79).08.
Texte intégralRésumé :
The development results of unified spectrometric module based on HPGe detectors with electric machine cooling for application in nuclear physical equipment of various application are presented. Unified module has cryostat with HPGe detector of the required size, electric machine cooler and electronic unit. The analysis of the cooling processes dynamics and HPGe detectors heating in cryostats, cooled by liquid nitrogen and EMC is made on the sample of the typical cooling circuits. Much attention is paid to design technological aspects of the cryostat development, cooled with electric coolers. With Solidworks software package the modal analysis of the cryostat cover and HPGe detector with various registration efficiency and weight was carried out. Based on the modal analysis of HPGe detector assembly the design of the holders where axial vibration mode was removed to the area of higher harmonics with smaller amplitudes was selected. The design of the developed unified module is reviewed. To increase EMC efficiency the additional radiators with heat tubes are installed and active method of blow off was applied. It secured the temperature decrease of EMC extender and accordingly provided the heat mode comfort for EMC operation what increases the safety of the developed module. The spectra of radioisotopes Co-57 and Co-60 are presented, registered by unified spectrometric module with HPGe detector with gamma radiation registration efficiency of 40%. The energy resolution by energies 122 and 1332 keV is 0,98 and 1,85 accordingly. The overall sizes of the unified module is 280×315×265 mm, its weight with the detector is about 20 kg. The module provides the radiation registration in any spatial position. It allows easy installation of the developed module on various equipment. The samples of the manufactured devices with unified spectrometric module are presented.
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Covi, M., B. Pressl, T. Günthner, K. Laiho, S. Krapick, C. Silberhorn et G. Weihs. « Liquid-nitrogen cooled, free-running single-photon sensitive detector at telecommunication wavelengths ». Applied Physics B 118, no 3 (4 février 2015) : 489–95. http://dx.doi.org/10.1007/s00340-015-6019-y.
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Di Mascio, Paolo, Etelvino J. H. Bechara et Joel C. Rubim. « Dioxygen NIR FT-Emission (1Δg → 3Σ−g) and Raman Spectra of 1,4-Dimethylnaphthalene Endoperoxide : A Source of Singlet Molecular Oxygen ». Applied Spectroscopy 46, no 2 (février 1992) : 236–39. http://dx.doi.org/10.1366/0003702924125528.
Texte intégralRésumé :
Singlet molecular oxygen (1O2) monomol light emission (O2, 1Δ g → 3Σ− g) generated during the thermodissociation of 1,4-dimethylnaphthalene endoperoxide (1,4-DMNO2) has been directly detected with the use of an FT spectrophotometer equipped with a liquid nitrogen-cooled InGaAs detector. The 1O2 quenching by β-carotene has been observed. The bimol emission has also been detected by the use of an intensified diode array detector and characterized by enhancement with 1,4-diazabicyclo[2.2.2]octane (DABCO). With a multichannel detector it was possible to obtain the Raman spectrum of 1,4-DMNO2 and to follow its conversion into the parent hydrocarbon 1,4-dimethylnaphthalene (1,4-DMN) by the decrease of the Raman 715-cm−1 peak intensity attributed to the O-O stretching mode.
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Barkan, S., K. F. Ihrig et M. B. Abott. « Unprecedented Performance Improvement For Thermoelectrically Cooled Si(Li) Detector for EDS ». Microscopy and Microanalysis 4, S2 (juillet 1998) : 198–99. http://dx.doi.org/10.1017/s1431927600021115.
Texte intégralRésumé :
High performance Si(Li) detectors for EDS applications must be cooled in order to eliminate excess leakage current and to reduce noise as a result of thermal excitation. The most common cooling method is the use of liquid nitrogen (LN), which has been commonly used during the last four decades. The LN method is relatively simple, however, it has some disadvantages such as: requiring a large dewar for storing the LN, the necessity of refilling it with LN, as well as some hazardous handling issues.Several years ago, Kevex introduced a new no-LN x-ray detector, the SuperDry, offering the customer a solution to the previously mentioned cooling problems. The SuperDry uses a thermoelectric device, a Peltier solid-state refrigerator, without any moving parts. The SuperDry covers all the disadvantages of the LN method, however, the temperature achieved has not reached the same low level as the LN products.
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Wu Hao, 吴昊, 朱一帆 Zhu Yifan, 丁青峰 Ding Qingfeng, 张金峰 Zhang Jinfeng, 上官阳 Shangguan Yang, 孙建东 Sun Jiandong et 秦华 Qin Hua. « 液氮制冷的AlGaN/GaN HEMT太赫兹探测器阵列特性研究 ». Infrared and Laser Engineering 51, no 12 (2022) : 20220225. http://dx.doi.org/10.3788/irla20220225.
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Nicholls, A. W., et P. E. Bovey. « A Cryo-transfer facility for the VG HB501 STEM ». Proceedings, annual meeting, Electron Microscopy Society of America 47 (6 août 1989) : 746–47. http://dx.doi.org/10.1017/s0424820100155700.
Texte intégralRésumé :
A recently developed cryotransfer facility has been successfully used to transfer both hydrated and dehydrated sections from a cryo-microtome to the column of the HB501 STEM with no significant warming or ice formation during transfer. This new accessory enables X-ray and energy loss analytical work to be carried out on frozen biological sections at much higher spatial resolution than is possible with conventional TEM systems.The construction and operation of the cryotransfer stage are summarized schematically in Figs. 1 and 2. Fig. 1 shows the central region of the HB501 optical column containing the objective lens (1), the post-specimen dc ana ac scan coil assembly (2), the annular dark field detector (3), the diffraction screen (4) and the airlock (5) through which room temperature specimens are normally loaded into the top-entry stage. A special stage base (6) is used which incorporates a liquid nitrogen-cooled block into which specimens are loaded by means of a side-entry manipulator (10). This manipulator is mounted on a support bracket (7) and enters the column through an isolation valve (8). Movement is achieved by a mechanism (not shown) mounted on the outer end of the bracket (7) and vacuum sealed by a bellows (11). The manipulator is liquid nitrogen-cooled by cooling pipes passing axially through the bellows. Loading and unloading of specimens is via an entry lock (9) which can be vented to dry nitrogen. A liquid nitrogen cooled, shrouded transfer rod (not shown) is used to transport specimens from the cryo-microtome to the entry lock.
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Keltner, Zachary, Katherine Kayima, Adam Lanzarotta, Luis Lavalle, Marina Canepa, Anthony E. Dowrey, Gloria M. Story, Curtis Marcott et André J. Sommer. « Prism-Based Infrared Spectrographs Using Modern-Day Detectors ». Applied Spectroscopy 61, no 9 (septembre 2007) : 909–15. http://dx.doi.org/10.1366/000370207781745982.
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A comparison of prism-based spectrographs to grating-based spectrographs is made when each of the systems is coupled to a modern-day liquid-nitrogen-cooled photovoltaic array detector. A comparison of the systems is also made using a room-temperature microbolometer array detector. Finally, infrared microspectroscopy of samples whose size is ∼10 micrometers will be demonstrated using a prism spectrograph outfitted with both types of detectors. The results of the study show that prism-based spectrographs offer an economical alternative to grating-based systems when spectral coverage is more critical than spectral resolution. The results also demonstrate that spectra with good signal-to-noise ratios can be collected on any of the systems with a total integration time of 10 seconds or less.
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Ren, Hao, Qun Zeng et Xi Hui Liang. « Characterization of Nd:Y3Al5O12 Thin Films Prepared by Electron Beam Evaporation Deposition ». Applied Mechanics and Materials 320 (mai 2013) : 150–54. http://dx.doi.org/10.4028/www.scientific.net/amm.320.150.
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Nd:YAG thin films have been prepared on Si (100) substrates by electron beam evaporation deposition. The surface morphologies, crystalline phases and optical properties of the Nd:YAG thin films were characterized by x-ray diffraction, scanning electron microscopy, photoluminescence spectroscopy, and spectrophotometer. The crystallization of Nd:YAG thin films was improved after annealing at 1100 °C for 1 hour in vacuum. Excited by a Ti:sapphire laser at 808 nm, photoluminescence spectra of Nd:YAG thin films were measured at room temperature, and the transition of4F3/24I11/2of Nd3+in YAG in the region of 1064 nm were detected by a liquid nitrogen cooled InGaAs detector array.
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Zhou, Jiangfeng, Zebang Ouyang, Junhui Liao, Zhuo Liang, Zhaohua Peng, Lei Zhang, Lifeng Zhang et Jian Zheng. « Coating μm TPB on a cylindrical detector and studying the sample films being cooled to LN and LHe temperatures ». Journal of Instrumentation 17, no 12 (1 décembre 2022) : P12001. http://dx.doi.org/10.1088/1748-0221/17/12/p12001.
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Abstract ALETHEIA is a newly established dark matter direct detection project that aims at hunting for low-mass WIMPs. TPB is widely implemented in liquid helium and argon experiments to shift VUV photons to visible light. We first report that we have successfully coated ∼ 3 μm TPB on the inner walls of a 10-cm cylindrical PTFE detector; we split the coating process into two steps to have all of the surfaces being coated with the same thickness; three independent methods were applied to figure out the thickness of the TPB coating layers, and consistent results were obtained. Second, with an SEM machine, we scanned the surface of TPB coating sample films exposed to different cryogenic temperatures. The first group of sample layers were immersed into a liquid nitrogen dewar for forty hours, the second group samples were cooled to 4.5 K for three hours, and the third group stayed at room temperature after coating. The SEM-scanned images of the sample films barely show any noticeable difference.
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Gérard, Pascal, Jean Louis Balladore, Jean Paul Martinez et Abdelghafour Ouabbou. « Energy-analyzing setup for backscattered electrons ». Proceedings, annual meeting, Electron Microscopy Society of America 50, no 2 (août 1992) : 1268–69. http://dx.doi.org/10.1017/s0424820100130973.
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We present in this paper an experimental device for determining for an electron beam incident normal to a target, the angular and energetic backscattered electron distribution as a function of the emission angle. The originality of our setup lies in the fact that under a normal incidence the particules reach the target which remains stationary. The detection system, placed on a rotating arm around the point of impact of the incident beam consists of a semiconductor detector (PIN diode). To enable its use as a detector of electron whose energy is comprised between 10 and 40 keV, a specially tailored electronic device was required. In order to enhance the energy resolution the PIN diode is cooled down at liquid nitrogen temperature.Figure 1 gives an example of the type of spectrum obtained. At a low energy, the electronic noise due the measurement setup appears in the form of the peak at 2 keV, irrespective of the nature of the target, the detection angle θ or the incident energy Eo chosen.
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Kail, Artjoms, Matthias Kaiser, Sergey Kim, Edward Loshevich et Alexander Sokolov. « Development of portable HPGe spectrometer for in situ measurements ». Nuclear Technology and Radiation Protection 30, no 2 (2015) : 154–57. http://dx.doi.org/10.2298/ntrp1502154k.
Texte intégralRésumé :
In situ applications require a very high level of portability of high-resolution spectrometric equipment. Usage of HPGe detectors for radioactivity measurements in the environment or for nuclear safeguard applications, to combat illicit trafficking of nuclear materials or uranium and plutonium monitoring in nuclear wastes, has become a norm in the recent years. Portable HPGe-based radionuclide spectrometer with electrical cooling has lately appeared on the market for in situ applications. At the same time deterioration of energy resolution associated with vibrations produced by cryocooler or high weight of the instrument, short time of autonomous operation and high price of these spectrometers are limiting their usage in many cases. In this paper we present development results of ultra compact hand held all-in-one spectrometer for in situ measurements based on HPGe detector cooled by liquid nitrogen without listing the above disadvantages.
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Angel, S. M., Thomas J. Kulp et Thomas M. Vess. « Remote-Raman Spectroscopy at Intermediate Ranges Using Low-Power cw Lasers ». Applied Spectroscopy 46, no 7 (juillet 1992) : 1085–91. http://dx.doi.org/10.1366/0003702924124132.
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A portable Raman system is described that has been developed for line-of-site spectral measurements of remotely located samples at intermediate ranges. Raman spectra were measured at distances up to 20 m with the use of a 40-mm-diameter collection optic ( f/500) and at 16.7 m with a 22-mm-diameter collection optic ( f/750). In all cases, low-power cw lasers were used with powers ranging from 23 to 100 mW. The system consists of a small f/4 image-corrected spectrograph with a liquid-nitrogen-cooled CCD detector and has been demonstrated with both an argon-ion laser, emitting at 488 nm, and an 809-nm diode laser. Applications of the system include monitoring of organic and inorganic compounds at toxic waste sites during remediation, process monitoring, and remote detection of highly toxic materials.
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Pfeil-Gardiner, Olivia, Deryck J. Mills, Janet Vonck et Werner Kuehlbrandt. « A comparative study of single-particle cryo-EM with liquid-nitrogen and liquid-helium cooling ». IUCrJ 6, no 6 (22 octobre 2019) : 1099–105. http://dx.doi.org/10.1107/s2052252519011503.
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Radiation damage is the most fundamental limitation for achieving high resolution in electron cryo-microscopy (cryo-EM) of biological samples. The effects of radiation damage are reduced by liquid-helium cooling, although the use of liquid helium is more challenging than that of liquid nitrogen. To date, the benefits of liquid-nitrogen and liquid-helium cooling for single-particle cryo-EM have not been compared quantitatively. With recent technical and computational advances in cryo-EM image recording and processing, such a comparison now seems timely. This study aims to evaluate the relative merits of liquid-helium cooling in present-day single-particle analysis, taking advantage of direct electron detectors. Two data sets for recombinant mouse heavy-chain apoferritin cooled with liquid-nitrogen or liquid-helium to 85 or 17 K were collected, processed and compared. No improvement in terms of resolution or Coulomb potential map quality was found for liquid-helium cooling. Interestingly, beam-induced motion was found to be significantly higher with liquid-helium cooling, especially within the most valuable first few frames of an exposure, thus counteracting any potential benefit of better cryoprotection that liquid-helium cooling may offer for single-particle cryo-EM.
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Wong, Brian J. F., Jon Lee, George T. Hashisaki, Michael W. Berns et Joseph Neev. « Thermal Imaging of the Temporal Bone in CO2 Laser Surgery : An Experimental Model ». Otolaryngology–Head and Neck Surgery 117, no 6 (décembre 1997) : 610–15. http://dx.doi.org/10.1016/s0194-59989770041-x.
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The unique properties of lasers create an enormous potential for specific treatment of chronic ear disease. Despite the widespread acceptance and use of the laser, however, a complete understanding of the time- and space-dependent temperature distribution in otic capsule bone immediately after pulsed laser exposure has not been elucidated. Using a liquid nitrogen-cooled mercury-cadmium telluride infrared detector, the temperature distribution in human cadaveric otic capsule bone was determined immediately after pulsed (100 msec) carbon dioxide laser exposure (0.3 to 4.0 W; 200 urn spot diameter). The time- and space-dependent temperature increases and thermal diffusion were determined as a function of the laser power density and were found to vary linearly.
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Charaf, U. K. « Visualizing emulsion polymer particles with an Scanning Electron Microscope equipped with transmission detector ». Proceedings, annual meeting, Electron Microscopy Society of America 52 (1994) : 890–91. http://dx.doi.org/10.1017/s0424820100172188.
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It is difficult to obtain good images of small emulsion polymer particles with an older model SEM which necessitates sputter coating and high accelerating voltage. For the purpose of screening a large number of samples before selecting some for TEM imaging off site, a transmission detector was fitted below the sample holder of an Amray 1600 (Turbo) SEM.Emulsion polymers with particle sizes from 10 to 100 μm were diluted in 1 % phosphotungstic acid (or other negative stain) and applied to Formvar and carbon coated grids. Lacking sophisticated freeze drying equipment, the grids with the sample films were cooled by immersing the stem of the grid holder in liquid nitrogen. They were then freeze dried in vacuo in an old sputter coaterInspite of some inherent difficulties, (such as high beam sensitivity), reasonably good resolution was obtained at 30 KV to magnifications of 150,000x.. Image processing was used, where applicable, to sharpen the images.
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Hawkins, E., et R. Cumming. « Enhanced chemiluminescence for tissue antigen and cellular viral DNA detection. » Journal of Histochemistry & ; Cytochemistry 38, no 3 (mars 1990) : 415–19. http://dx.doi.org/10.1177/38.3.1689340.
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The ability to use enhanced chemiluminescence (ECL) to detect horseradish peroxidase as a label for tissue antigens and cellular viral DNA was demonstrated. A liquid nitrogen-cooled charged-coupled device (CCD) was used to detect light output, which was visualized on a monitor or was quantitated using an attached microcomputer. In a tissue antigen model, equivalent sensitivity was observed between ECL and colorimetric detection.
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Zani, A., F. Alessandria, A. Andreani, A. Castoldi, S. Coelli, D. Cortis, D. D’Angelo et al. « The ASTAROTH Project : enhanced low-energy sensitivity to Dark Matter annual modulation ». Journal of Physics : Conference Series 2156, no 1 (1 décembre 2021) : 012060. http://dx.doi.org/10.1088/1742-6596/2156/1/012060.
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Abstract ASTAROTH is a novel R&D project which aims at improving the physics reach of future direct dark matter detection experiments based on NaI(Tl) scintillating crystals. There is a strong need to test the long standing DAMA positive observation of an annual modulation that could be due to Dark Matter (DM), with the same target material and in a model independent way. ASTAROTH aim is the enhancement of the sensitivity to the annual modulation signal, compared with present technology, by lowering the detection energy threshold in order to observe sub-keV recoils for the first time. This can be achieved by reading the scintillation light from the NaI(Tl) crystals with arrays of Silicon PhotoMultipliers (SiPM), and placing the detectors in a cryogenic environment. SiPMs feature lower dark noise than Photomultiplier Tubes (PMTs) at T < 150 K and allow for higher light collection. The cooling medium is liquid Argon, as it is an excellent scintillator that can be instrumented to act as a veto against several backgrounds. Here we present the status of the ASTAROTH project, introducing the innovative design of the detector chamber that will be used for the demonstration of the technology. Then, we will show the preliminary results of our first ever measurements performed on a single NaI(Tl) crystal read out by one SiPM array in a cryogenic set-up cooled with liquid nitrogen.
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Chandrasekhar, T., N. M. Ashok et Sam Ragland. « Near Infrared High Angular Resolution Observations of Stars and Circumstellar Regions by the Technique of Lunar Occultations ». Symposium - International Astronomical Union 158 (1994) : 376–78. http://dx.doi.org/10.1017/s0074180900107971.
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A program of High Angular Resolution observations of stars and their circumstellar regions using the technique of lunar occultations has been initiated at the 1.2 m telescope at Gurushikhar (24°39′ N, 72°47′ E), India. A liquid nitrogen cooled InSb detector based high speed Infrared photometer with millisecond data acquisition capabilities has been developed for the near Infrared region (1–5 μm) and eight occultations have been successfully observed in the K band (2.2 μm). The sources are (IRC No. -10578, +10013, +20034, +30094, +20190, +20200, +20073 and +00198. The diffraction pattern is clearly seen in all the observations. A convolution analysis involving the system frequency response, filter bandwidth and one dimensional source structure has been carried out to fit the data. System capability has been determined to be ~ 6 milliarcseconds.
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Story, Gloria M., Curtis Marcott et Rina K. Dukor. « A Method For Analysis Of Clinical Tissue Samples Using Ft-Ir Microspectroscopic Imaging ». Microscopy and Microanalysis 5, S2 (août 1999) : 68–69. http://dx.doi.org/10.1017/s1431927600013660.
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During the past decade, Fourier transform infrared (FT-IR) microspectroscopy has been used successfully in many studies to differentiate normal and diseased tissue samples obtained from a variety of organs, including colon, cervix, prostate, and breast. IR images were constructed by collecting spectra point-by-point using a mapping stage on a FT-IR microscope equipped with a single-element detector. Five years ago, in collaboration with NIH scientists Dr. Neil Lewis and Dr. Ira Levin, Procter and Gamble researchers developed a technique for performing vibrational spectroscopic imaging microscopy using a liquid-nitrogen-cooled focal-plane array (FPA) detector and a step-scanning FT-IR spectrometer coupled to a refractive microscope. With this configuration, equipped with a new 64-pixel x 64-pixel Mercury-Cadmium-Telluride (MCT) FPA detector, we are able to image an 800-μm x 800-μm area of a specimen without moving the sample.For all of these IR imaging studies, the tissue samples were prepared in a manner that was special and different from that commonly used in a pathology laboratory, i.e.,the histopathology sample was not identical to the spectroscopic sample.
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Ackerley, C. A., et L. E. Becker. « X-ray microanalysis of mineralized deposits in a variety of pathological conditions in the brain ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 866–67. http://dx.doi.org/10.1017/s0424820100140701.
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Although a small degree of mineralization can be a common occurrence without associated pathological symptoms, certain diseases of the brain do however exhibit distinct increases in mineralization with characteristic distributions l>2. In this study, tissues from a number of these disorders were prepared for x-ray microanalysis in several ways. Where possible, material was slam frozen on a liquid nitrogen cooled polished copper block, cryosections prepared and freeze dried in the scanning transmission electron microscope (STEM) using a cold stage prior to analysis by energy dispersive x-ray spectrometry (EDS). In addition, samples were freeze substituted for several days, embedded in LR white and cut on dry knives before analysis. Where only formalin fixed paraffin embedded materials were available, .5μ.m sections were cut and mounted on carbon planchets. The specimens were then deparaffinized with xylene and viewed with the backscatter electron detector (BEI) in the scanning electron microscope (SEM) and analyzed by EDS.
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Jones, Jay Pendell, Ronald E. Wambles, Charles K. Mann et Thomas J. Vickers. « Effect on Noise of Intensity-Axis Correction of Spectra Recorded with Charge-Coupled Device Detectors ». Applied Spectroscopy 56, no 5 (mai 2002) : 564–69. http://dx.doi.org/10.1366/0003702021955321.
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We have examined the effect of intensity-axis correction on noise in white light spectra recorded with charge-coupled device (CCD) detectors. Measurements were made with five detectors in Raman spectrometers. Detectors were both liquid-nitrogen and thermoelectrically cooled devices and one room temperature device. Both random and pattern noise have been considered. We used cross-correlation of noise sets to provide an indicator of a fixed pattern in the spectra and an assessment of the efficacy of the correction procedure in removing this pattern. For four of the five detectors intensity-axis correction provided a significant improvement in signal-to-noise ratio. Correction was particularly important for measurements made with lower-cost CCD detectors of the kind proposed for process control instruments.
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Huallpa, Edgar A., Paula F. S. Farina, Julio Capo, Linilson R. Padovese et Hélio Goldenstein. « The Use of Barkhausen Noise to Study the Martensitic Phase Transformation ». Solid State Phenomena 172-174 (juin 2011) : 184–89. http://dx.doi.org/10.4028/www.scientific.net/ssp.172-174.184.
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The use of magnetic Barkhausen (MBN) noise methods to detect the austenite to martensite phase transformation during cooling of steel specimens was explored, using three different configurations: conventional Barkhausen noise emission stimulated by an alternating magnetic field, the Okamura method, that measures magnetic noise emission under a fixed DC field and a novel experimental technique that measures spontaneous magnetic emission during transformation, in the absence of any external field. The phenomena associated with the phase transformation were also followed by electrical resistivity measurements and the resulting samples were characterized using optical and scanning electron microscopy. MBN measurements on a AISI D2 tool steel austenitized at 1473K and cooled to liquid nitrogen temperature exhibited a clear change near 225 K during cooling, corresponding to the Ms (martensite start ) temperature, as confirmed by resistivity measurements. Spontaneous magnetic noise emission measurements made in situ during cooling of a sample immerged in liquid nitrogen showed that individual “burst” phenomena could be detected, in a manner similar to acoustic emission (AE) measurements. This magnetic emission (ME) can thus be considered a new experimental tool for the study of martensite transformations in ferrous alloys.
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Zuo, J. M., J. C. H. Spence, R. Hoier et J. Wheatley. « A CCD parallel detection system for electron diffraction and imaging with large dynamic range ». Proceedings, annual meeting, Electron Microscopy Society of America 46 (1988) : 656–57. http://dx.doi.org/10.1017/s0424820100105345.
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The quantitative recording of convergent-beam electron diffraction patterns (CBED), spot patterns. RHEED patterns and high resolution images requires a parallel detection system with large dynamic range. Systems based on YAG detectors and television tubes are ideal for recording rapidly changing events, however the integration of many such images provides a limited improvement in dynamic range since the read-out process itself introduces noise. Charge-coupled devices (CCDs) have been shown to provide a promising alternative for recording diffraction patterns. Our system is intended for recording the weak reflections from reconstructed surfaces in transmission on the U.H.V. Philips-Gatan EM430. and for structure-factor refinement by quantitative CBED (see these proceedings). Our CCD system, fitted to a Philips EM400, is based on the Photometries CC210 camera (see figure 1). A YAG single-crystal screen is bonded to fibre-optics, which transfers the image out of the vacuum and onto a Thomson-CSF TH7882CDA 576x384x14 bit CCD cooled by liquid nitrogen.
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Timokhin, Viktor M., Vladimir M. Garmash et Valentin A. Tedzhetov. « Technology of thermally stimulated diagnostics of anisotropy and optical axes in crystals ». Modern Electronic Materials 6, no 4 (30 décembre 2020) : 125–32. http://dx.doi.org/10.3897/j.moem.6.4.65351.
Texte intégralRésumé :
For implementing the technology of thermally stimulated diagnostics of anisotropy and optical axes in crystals, the sample is thermostated at a temperature not exceeding the melting point, an electric field not exceeding the breakdown field is applied to the sample and polarization is produced for a time greater than the relaxation time at this temperature. After that, without switching off the electric field, the sample is cooled to the liquid nitrogen temperature, following which the field is switched off, the sample is linearly heated to a temperature above the polarization temperature and the resultant thermally stimulated depolarization (TSD) spectra taken along and perpendicular to the optical axis of the crystal are examined. When comparing the spectra the presence of anisotropy is detected and the direction of the optical axes is determined from the magnitude and presence of the TSD maxima.
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Gruet, S., A. Morvan, O. Pirali, T. Chamaillé, E. Bouisset et M. Vervloet. « Fourier transform far-infrared spectroscopy of HN2+ on the AILES beamline of synchrotron SOLEIL ». Canadian Journal of Physics 91, no 11 (novembre 2013) : 937–40. http://dx.doi.org/10.1139/cjp-2012-0530.
Texte intégralRésumé :
We report the pure rotation spectrum of HN2+ as measured by Fourier transform (FT) absorption spectroscopy in the 20–40 cm−1 spectral range. The cations are produced in a liquid nitrogen cooled hollow cathode discharge cell developed on the AILES beamline of synchrotron SOLEIL. The setup was optimized by recording rotation–vibration spectra of H3+ (with the ν2 band centered at about 2521 cm−1), HN2+ (with the ν1 band centered at about 3234 cm−1), and HCO+ (with the ν1 band centered at about 3089 cm−1). Many rotation–vibration lines have been assigned for each ion and five pure rotational transitions have been detected for HN2+. These results demonstrate the feasibility of recording far-infrared spectra of cationic species using FT broad band spectroscopy associated with the bright synchrotron radiation continuum as an alternative to laser-based frequency tunable techniques.
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Jaakkola, P., J. D. Tate, M. Paakkunainen, J. Kauppinen et P. Saarinen. « Instrumental Resolution Considerations for Fourier Transform Infrared Gas-Phase Spectroscopy ». Applied Spectroscopy 51, no 8 (août 1997) : 1159–69. http://dx.doi.org/10.1366/0003702971941683.
Texte intégralRésumé :
Instrumental resolution has a significant effect on the performance of Fourier transform infrared (FT-IR) spectrometers used for gasphase analysis. Low-resolution FT-IR spectroscopy offers some valuable advantages compared with the traditional high-resolution FT-IR gas-phase spectroscopy, especially in nonlaboratory environments. First, high signal-to-noise ratio (SNR) spectra can be acquired in field conditions without the use of traditional liquid nitrogen-cooled detectors. Second, the dynamic range for quantitative analysis is larger for low-resolution spectroscopy than for high-resolution due to the lower absorbance values and lower noise levels. Third, spectral analysis speed is increased and data storage requirements are substantially reduced. The purpose of this study was to investigate the effect of instrumental resolution on FT-IR gas-phase analysis. The effects of spectral resolution on sensitivity, selectivity, accuracy, precision, spectral overlap, dynamic range, and nonlinearity are separately discussed.
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Bow, J. S., Y. C. Hung, M. J. Kim, R. W. Carpenter, W. M. Kim, S. K. Lee et S. G. Kim. « High-resolution TEM and AEM study in (Au, Tin) thin film on (100) silicon ». Proceedings, annual meeting, Electron Microscopy Society of America 53 (13 août 1995) : 554–55. http://dx.doi.org/10.1017/s0424820100139147.
Texte intégralRésumé :
The cross-sectional microstructure of a (Au, TiN) thin film deposited on a (100) Si substrate without further heat treatment was studied by CTEM, HRTEM, and AEM. HTREM was performed in a Topcon 002B microscope with interpretable resolution limit of 0.18 nm, and high spatial AEM was done in a Philips 400ST field emission gun microscope at 100 kV using a Gatan 666 parallel-detection electron energy loss spectrometer. Cross-section specimens of the interface were prepared by traditional polishing and ion milling. Temperatures used in the whole process of TEM specimen preparation were below 100°C and a liquid-nitrogen-cooled cold stage was used in ion milling to prevent interaction between Au and Si.Ti was co-deposited with Au by sputtering in a nitrogen atmosphere to increase the hardness of the thin Au contact film. Fig. 1a shows the microstructure of the (Au, Ti, N)/Si contact. The features of this microstructure are very similar to the those of pure gold thin films on Si substrates annealed below the Au-Si eutectic temperature (363°C). The thin, white layer was considered to be the original Au/Si interface by Chang et al.
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Zarling, E. J., et M. Clapper. « Technique for gas-chromatographic measurement of volatile alkanes from single-breath samples. » Clinical Chemistry 33, no 1 (1 janvier 1987) : 140–41. http://dx.doi.org/10.1093/clinchem/33.1.140.
Texte intégralRésumé :
Abstract For detection of small quantities of alkanes that are present in expired breath, these gases have hitherto been concentrated, either by passing large volumes of breath through a liquid-nitrogen-cooled precolumn or by use of a closed collection system. Here, we describe a technique for analyzing small volumes of gas from single-breath samples from humans, in which no precolumn is required. Results are linearly related to sample concentrations of ethane, propane, butane, and pentane in the range 0 to 13 nmol per liter of air (r = 0.999). Within-run coefficients of variation were less than 15%. Breath samples could be stored for as long as 10 h without loss of the alkanes. We also report alkane concentrations in samples of alveolar gas and total breath collected from normal subjects. This technique appears to be well suited for measuring alkane concentrations in single-breath samples.
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Lavoir, MC, N. Rumph, KJ Betteridge et SP Leibo. « Cryopreservation of germ cells from bovine fetal ovaries ». Reproduction, Fertility and Development 8, no 2 (1996) : 267. http://dx.doi.org/10.1071/rd9960267.
Texte intégralRésumé :
Bovine fetuses at stages required for studies of female germ cells (primordial germ cells and oogonia) become available from the abattoir at unpredictable times. To alleviate this logistical problem, a procedure to cryopreserve these ovarian germ cells has been devised. Fetal ovarian cells were dispersed and suspended in 1.5 M dimethyl sulfoxide (DMSO) prepared in modified TCM 199 medium. The suspensions were aspirated into plastic semen straws, cooled, seeded to induce ice formation at -7 degrees C, and then cooled at 1 degree C min-1 to -70 degrees C before being plunged into liquid nitrogen at -196 degrees C for storage. The straws were thawed at a moderate rate of approximately 250 degrees C min-1, the DMSO was diluted 28-fold with culture medium, and then the cells were cultured for > 2 h before their viability was tested or they were used for nuclear transfer. No statistically significant difference in viability before and after cryopreservation was detected by vital staining with fluorescein diacetate (P > 0.05). When frozen-thawed germ cells were fused to cytoplasts, the cleavage rate of the resultant reconstructed embryos 44 h after fusion was 31%, although none developed into blastocysts. It is concluded that cryopreservation of bovine fetal ovarian germ cells is feasible and can play a major role in facilitating future experimentation.
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Yamashita, Eiki, Akifumi Higashiura, Masato Yoshimura, Kazuya Hasegawa, Yukito Furukawa, Toru Ohata, Takashi Kumasaka, Go Ueno, Masaki Yamamoto et Atsushi Nakagawa. « IPR Beamline for Macromolecular Assemblies at SPring-8 (BL44XU) ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C1684. http://dx.doi.org/10.1107/s2053273314083156.
Texte intégralRésumé :
Biological macromolecular assemblies play significant roles in many biological reaction systems, including energy transfer, protein synthesis, protein degradation and signal transduction. A detailed understanding of the functions of the macromolecular assemblies requires information derived from three-dimensional atomic structures. X-ray crystal structure analysis is one of the most powerful methods to determine the three-dimensional structures of macromolecular assemblies at atomic level. Since features of crystals of biological macromolecular assemblies are extremely weak diffraction power and narrow space between the diffraction spots, it is essential to use high brilliance and high paralleled synchrotron radiation for diffraction data collection from crystals of biological macromolecular assemblies. The Institute for Protein Research (IPR) of Osaka University is operating a beamline for crystal structure analysis of biological macromolecular assemblies at SPring-8 (BL44XU). This beamline is designed to collect high quality diffraction data from biological macromolecular assembly crystals with large unit cells. The light source of this beamline is a SPring-8 standard type in-vacuum undulator. Liquid nitrogen cooled double crystal monochromator and horizontal focusing mirror are used as the optical components. BSS (Beamline Scheduling Software), which is SPring-8 protein crystallography beamline standard GUI, is installed to unify user operation throughout protein crystallography beamlines in the SPring-8. We have recently upgraded to a high speed air-bearing goniostat and installed a high performance CCD detector, MX-300HE. Present status and future plan of the beamline will be presented.
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Genuzio, Francesca, Tomasz Giela, Matteo Lucian, Tevfik Onur Menteş, Carlo Alberto Brondin, Giuseppe Cautero, Piotr Mazalski, Stefano Bonetti, Jozef Korecki et Andrea Locatelli. « A UHV MOKE magnetometer complementing XMCD-PEEM at the Elettra Synchrotron ». Journal of Synchrotron Radiation 28, no 3 (30 mars 2021) : 995–1005. http://dx.doi.org/10.1107/s1600577521002885.
Texte intégralRésumé :
We report on a custom-built UHV-compatible Magneto-Optical Kerr Effect (MOKE) magnetometer for applications in surface and materials sciences, operating in tandem with the PhotoEmission Electron Microscope (PEEM) endstation at the Nanospectroscopy beamline of the Elettra synchrotron. The magnetometer features a liquid-nitrogen-cooled electromagnet that is fully compatible with UHV operation and produces magnetic fields up to about 140 mT at the sample. Longitudinal and polar MOKE measurement geometries are realized. The magneto-optical detection is based on polarization analysis using a photoelastic modulator. The sample manipulation system is fully compatible with that of the PEEM, making it possible to exchange samples with the beamline endstation, where complementary X-ray imaging and spectroscopy techniques are available. The magnetometer performance is illustrated by experiments on cobalt ultra-thin films, demonstrating close to monolayer sensitivity. The advantages of combining in situ growth, X-ray Magnetic Circular Dichroism imaging (XMCD-PEEM) and MOKE magnetometry into a versatile multitechnique facility are highlighted.
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Glosík, Juraj, P. Hlavenka, R. Plašil, F. Windisch, D. Gerlich, A. Wolf et H. Kreckel. « Action spectroscopy of and D 2 H + using overtone excitation ». Philosophical Transactions of the Royal Society A : Mathematical, Physical and Engineering Sciences 364, no 1848 (20 septembre 2006) : 2931–42. http://dx.doi.org/10.1098/rsta.2006.1866.
Texte intégralRésumé :
The ion and its deuterated isotopologues H 2 D + , D 2 H + and play an important role in astrophysical and laboratory plasmas. The main challenge for understanding these ions and their interaction at low temperatures are state-specific experiments. This requires manipulation and a simple but efficient in situ characterization of their low-lying rotational states. In this contribution we report measurements of near infrared (NIR) absorption spectra. Required high sensitivity is achieved by combining liquid nitrogen cooled plasma with the technique of NIR cavity ringdown absorption spectroscopy. The measured transition frequencies are then used for exciting cold ions stored in a low-temperature 22-pole radiofrequency ion trap. Absorption of a photon by the stored ion is detected by using the laser-induced reactions technique. As a monitor reaction, the endothermic proton (or deuteron) transfer to Ar is used in our studies. Since the formed ArH + (or ArD + ) ions are detected with near unit efficiency, the stored ions can be characterized very efficiently, even if there are just a few of them.
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Baca Castex, C., G. Dalvit, M. Miragaya, A. Alonso, M. Pinto, V. Etcharren, C. Castaneira et L. Losinno. « 77 PREGNANCY RATES AFTER VITRIFICATION OF FRESH AND COOLED EQUINE EMBRYOS USING THE CRYOTOP METHOD ». Reproduction, Fertility and Development 23, no 1 (2011) : 144. http://dx.doi.org/10.1071/rdv23n1ab77.
Texte intégralRésumé :
Cryopreservation of equine embryos is still not a routine procedure. Pregnancies have been obtained after transfer of vitrified embryos of less than 300 μm (Eldridge-Panuska et al. 2005). The aim of this study was to use the cryotop method (Kuwayama, 2007) to obtain pregnancies after transfer of vitrified thawed cooled and fresh embryos collected in our clinical embryo transfer programme. Embryos were assigned either to be vitrified within 3 h of collection or to be cooled for 18–24 h before vitrification. All embryos were vitrified and thawed by Cryotop Vitrification Kit® (Cryo Tech Laboratory®). Briefly, they were equilibrated in a solution containing ethylene glycol (EG), dimethylsulphoxide (DMSO) in TCM-199 for 10 to 25 min. Then they were moved to vitrification solution containing EG, DMSO, and sucrose in TCM-199 and loaded with a glass capillary onto the top of the film strip. After loading, almost all the solution was removed to leave only a thin layer covering the embryo, and the sample was quickly immersed into liquid nitrogen and covered with a protective cap. The time between entry to vitrification solution and nitrogen was from 1 to 3 min. At warming, the strip was immersed directly for 1 min into a 37°C medium containing sucrose in TCM-199. The embryo was incubated 3 min in a diluent solution, washed twice 5 min each in washing solution, and further cultured in DMEM F-12 with 10% FBS at 38.5°C 5% CO2 between 2 to 5 h. For transfer, the embryo was loaded in 0.5-mL straws. All recipient mares had ovulated 4 to 7 days before nonsurgical transfer. Pregnancies were detected 6 to 8 days later. A total of 15 embryos, grades 1 to 2, were obtained. Fresh embryos (n = 7) ranged between 250 and 800 μm, and refrigerated embryo (n = 8) diameter was between 130 and 550 μm. Pregnancy rates were 37.5% (3/8) for embryos cooled before vitrification and 28.6% (2/7) for embryos vitrified within 3 h. The overall pregnancy rate was 33.3% (5/15). Shipping cooled embryos allows maintaining a large number of recipients far away from donors, without decreasing pregnancy rate. It also makes it possible to send embryos to a specialised laboratory in order to be vitrified and preserved until recipients are available. Equine embryos collected 6 days after ovulation are generally smaller than 300 μm and have shown the highest survival rate after cryopreservation. However, the embryo recovery rate is higher when flushing is performed at Day 7 or 8. This cryopreservation protocol could provide a way to vitrify fresh and cooled embryos up to 550 μm, which would prevent the loss of valuable embryos collected in more advanced stages of development. In summary, pregnancies can be obtained after cooling for 18 to 24 h and vitrification of embryos collected 7 or 7.5 days after.
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Kenik, Edward A. « Application of analytical electron microscopy to studies of equilibrium and non-equilibrium segregation in materials ». Proceedings, annual meeting, Electron Microscopy Society of America 50, no 2 (août 1992) : 1214–15. http://dx.doi.org/10.1017/s0424820100130705.
Texte intégralRésumé :
Segregation of solute atoms to grain boundaries, dislocations, and other extended defects can occur under thermal equilibrium or non-equilibrium conditions, such as quenching, irradiation, or precipitation. Generally, equilibrium segregation is narrow (near monolayer coverage at planar defects), whereas non-equilibrium segregation exhibits profiles of larger spatial extent, associated with diffusion of point defects or solute atoms. Analytical electron microscopy provides tools both to measure the segregation and to characterize the defect at which the segregation occurs. This is especially true of instruments that can achieve fine (<2 nm width), high current probes and as such, provide high spatial resolution analysis and characterization capability. Analysis was performed in a Philips EM400T/FEG operated in the scanning transmission mode with a probe diameter of <2 nm (FWTM). The instrument is equipped with EDAX 9100/70 energy dispersive X-ray spectrometry (EDXS) and Gatan 666 parallel detection electron energy loss spectrometry (PEELS) systems. A double-tilt, liquid-nitrogen-cooled specimen holder was employed for microanalysis in order to minimize contamination under the focussed spot.
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Yamada, Yusuke, Naohiro Matsugaki, Masahiko Hiraki, Ryuichi Kato et Toshiya Senda. « In-situ diffraction experiments at the Photon Factory MX beamlines ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C500. http://dx.doi.org/10.1107/s2053273314094996.
Texte intégralRésumé :
Crystallization trial is one of the most important but time-consuming steps in macromolecular crystallography. Once a crystal appears in a certain crystallization condition, the crystal is typically harvested from the crystallization drop, soaked into a cryoprotection buffer, flash-cooled with a liquid nitrogen or cold gas flow and finally evaluated its diffraction quality by an X-ray beam. During these long process, crystal may be damaged and the result from the diffraction experiment does not necessarily reflect a nature of the crystal. On in-situ diffraction experiment, where a crystal in a crystallization drop is directly irradiated to an X-ray beam, a diffraction image from a crystal without any external factors such as harvesting and cryoprotection and, as a result, a nature of crystal can be evaluated quickly. In the Photon Factory, a new table-top diffractometer for in-situ diffraction experiments has been developed. It consists of XYZ translation stages with a plate handler, on-axis viewing system with a large numeric aperture and a plate rack where ten crystallization plates can be placed. These components sit on a common plate and it is placed on the existing diffractometer table in the beamline endstation. The CCD detector with a large active area and a pixel array detector with a small active area are used for acquiring diffraction images from crystals. Dedicated control software and user interface were also developed. Since 2014, user operation of the new diffractometer was started and in-situ diffraction experiments were mainly performed for evaluations of crystallization plates from a large crystallization screening project in our facility. BL-17A [1], one of micro-focus beamlines at the Photon Factory, is planned to be upgraded in March 2015. With this upgrade, a new diffractometer, which has a capability to handle a crystallization plate, will be installed so that diffraction data sets from crystals in crystallization drop can be collected.
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Zani, Veronica, Danilo Pedron, Roberto Pilot et Raffaella Signorini. « Biocompatible Temperature Nanosensors Based on Titanium Dioxide ». Proceedings 60, no 1 (2 novembre 2020) : 16. http://dx.doi.org/10.3390/iecb2020-07086.
Texte intégralRésumé :
The measurement of temperature is of fundamental importance in a huge scale of applications, from nanomedicine, where the early detection of tumorous cells is an essential requirement, to microelectronics and microcircuits. Optical sensors with a micro/nano-spatial resolution can be used for temperature determination within a biological frame. Within this context, Raman spectroscopy is particularly interesting: the inelastic scattering of light has the advantage of a contactless measurement and exploits the temperature-dependence of intensities in the spectrum by observing the intensity ratio of anti-Stokes and Stokes signals. Titanium dioxide can be regarded as a potential optical material for temperature detection in biological samples, thanks to its high biocompatibility, already demonstrated in literature, and to its strong Raman scattering signal. The aim of the present work is the realization of biocompatible optical thermometers, with a sub-micrometric spatial resolution, made of titanium dioxide. Raman measurements have been performed on anatase powder using 514.5, 568.2 and 647.1 nm excitation lines of the CW Ar/Kr ion laser. The laser beam was focalized through a microscope on the sample, kept at defined temperature using a temperature controller. The Stokes and anti-Stokes scattered light was analyzed through a triple monochromator and detected by a liquid nitrogen-cooled CCD camera. Raw data were analyzed with Matlab and Raman spectrum parameters—such as area, intensity, frequency position and width of the peak—were calculated using a Lorentz fitting curve. Preliminary results showed that good reliable temperatures can be obtained.
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Barfield, J. P., R. Sanchez, E. L. Squires et G. E. Seidel. « 60 VITRIFICATION AND CONVENTIONAL CRYOPRESERVATION OF EQUINE EMBRYOS ». Reproduction, Fertility and Development 21, no 1 (2009) : 130. http://dx.doi.org/10.1071/rdv21n1ab60.
Texte intégralRésumé :
Vitrification and conventional cryopreservation are effective methods of preserving equine embryos smaller than 300 μm in diameter. This study was designed to compare pregnancy rates using these methods to cryopreserve embryos of similar size. Sport horse mares approximately 2–20 years old were flushed nonsurgically between Days 6.5 and 7 post-ovulation with 2 L of lactated-Ringers solution (Braun, Melsungen, Germany). Thirty-one embryos were collected, washed 4 times with 1 mL of ViGro® holding medium (Bioniche Animal Health, Bogart, GA), graded for quality, measured for diameter, and blocked into 2 groups (<200 μm, 200 to 300 μm). Embryos were either vitrified with a commercial equine vitrification kit (Bioniche Animal Health) according to the manufacturer’s instructions in 0.25-mL straws or subjected to a slow cooling method. For vitrification, embryos were sequentially transferred to 2 wells containing 0.5 mL of 2 Syngro®-based vitrification solutions (VS1 and VS2) and held for 5 min each. Embryos were incubated in a third vitrification solution (VS3) for 45 s during which time they were loaded into straws. Straws were held in liquid nitrogen-cooled air for 1 min before submersion in liquid nitrogen. For slow freezing, embryos were consecutively placed into 0.5 mL of the following Syngro®-based solutions for 5 min each: 1.8 m glycerol, 1.8 m glycerol + 1.8 m ethylene glycol (EG), and 0.9 m glycerol + 0.9 m EG + 0.5 m galactose. Embryos were loaded into 0.25-mL straws, placed in a chamber pre-cooled to –6°C, and held for 10 min. Straws were seeded after 2 min. The temperature was lowered to –32°C at a rate of 0.5°C min–1. Embryos were then plunged into liquid nitrogen within 3 min of reaching –32°C. For warming vitrified embryos, straws were held in air for 10 s followed by submersion into a 35°C water bath for 20 s. Straws were flicked 5 times to mix the diluent solution with the VS3-containing embryos, which were transferred within 7 min of being thawed. For thawing conventionally frozen embryos, straws were held in air for 10 s followed by submersion into a 35°C water bath for 30 s. Contents of the straw were immediately expelled into a Petri dish, and the embryos were transferred immediately to 0.5 mL of 1.2 m glycerol +1.2 m EG + 0.5 m galactose and held for 5 min. This was followed by a 5-min incubation in 0.5 mL of each of the following solutions: 0.6 m glycerol + 0.6 m EG + 0.5 m galactose, 0.25 m glycerol + 0.25 m EG + 0.5 m galactose, and 0.5 m galactose. After exposure to the last solution, embryos were transferred to Syngro®, loaded into a straw, and immediately transferred into 2-year-old virgin recipients 6 days after ovulation as detected by rectal palpation and ultrasonography. Of the 21 embryos <200 μm collected, 11 were vitrified and 10 frozen slowly. Three of these 11 vitrified embryos and 7 of 10 slow-frozen embryos resulted in Day 16 pregnancies (27 and 70%, respectively). None of the embryos >200 μm resulted in pregnancies in either the vitrification (n = 5) or slow-freeze treatments (n = 4).
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Kim, M. J., R. W. Carpenter, D. K. Schroder et J. H. Wohlgemuth. « Nanoanalysis of impurity precipitation on grain boundaries in polysilicon ». Proceedings, annual meeting, Electron Microscopy Society of America 49 (août 1991) : 810–11. http://dx.doi.org/10.1017/s0424820100088361.
Texte intégralRésumé :
Polycrystalline silicon (polysilicon) has been the subject of extensive studies in recent years due to its wide applications in microelectronics and solar cells, see for example references. In most cases of interest impurities segregated to the grain boundaries strongly modify the electronic properties of this material. Understanding the behavior of impurities in polysilicon requires a detailed knowledge of their distribution, phase and thermodynamical stability. In the present study, the structure and chemistry of grain boundaries in polysilicon were characterized by HREM and very high spatial resolution FEG/AEM.The specimen materials are Solarex cast polysilicon used for solar cells, which are manufactured under a proprietary method called the ubiquitous crystallization process. The samples for TEM observations were cut from the ingot perpendicular to its growth direction and then thinned to electron transparency by mechanical polishing and ion milling. HREM was performed at 200kV in an ISI-002B. Microanalysis was done using a Philips 400ST/FEG microscope coupled to a Gatan parallel-detection electron energy loss spectrometer, at 100kV. A liquid nitrogen cooled specimen holder was used for nanoprobe experiments to minimize specimen contamination and local specimen heating.
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Terada, Nobuo, Nobuhiko Ohno, Hiroshi Ohguro, Zilong Li et Shinichi Ohno. « Immunohistochemical Detection of Phosphorylated Rhodopsin in Light-exposed Retina of Living Mouse with In Vivo Cryotechnique ». Journal of Histochemistry & ; Cytochemistry 54, no 4 (6 janvier 2006) : 479–86. http://dx.doi.org/10.1369/jhc.5a6844.2006.
Texte intégralRésumé :
The purpose of this study is to analyze the time-dependent molecular states of rhodopsin (Rho) phosphorylation in the specimens originating from eyeballs cryoimmobilized in situ in living animals. Whole eyeballs of living mice under various dark- and light-exposure conditions were quickly frozen using the in vivo cryotechnique with isopentane-propane cryogen cooled down in liquid nitrogen (−196C). The frozen whole-mount eyeballs were freeze substituted in acetone containing paraformaldehyde and embedded in paraffin wax. Deparaffinized sections were immunostained with anti-phosphorylated 334Ser Rho (P-Rho334) antibody. Immunoreactivity of P-Rho334 was specifically recognized in the outer segments of mouse retinas exposed to daylight. In the 12-h dark-adapted retinas, P-Rho334 immunoreactivity was completely eliminated. Moreover, in other retinas dark adapted for 12 or 36 hr and then exposed under the safety red light for 2 min, it was still barely recognized. Even in the eyeballs exposed to strong visible light for 10 sec, it was not detected. However, after 30, 60, and 180 sec of visible light exposure, P-Rho334 immunoreactivity was definitely recovered, similar to that under daylight condition. This is a new immunohistochemical approach to visualize the time-dependent Rho phosphorylation of living mice using the in vivo cryotechnique, in which changes could be detected within seconds following exposure to light.
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Mucci, N., F. Hozbor, G. G. Kaiser, E. Sanchez et R. H. Alberio. « 106 PREGNANCY RATE AFTER EMBRYO TRANSFER OF IN VIVO-PRODUCED OVINE EMBRYOS CRYOPRESERVED BY SLOW FREEZING OR VITRIFICATION ». Reproduction, Fertility and Development 22, no 1 (2010) : 212. http://dx.doi.org/10.1071/rdv22n1ab106.
Texte intégralRésumé :
Although slow freezing is the method of choice to cryopreserve in vivo-produced ovine embryos, vitrification has became an alternative procedure mostly developed for in vitro-produced bovine embryos. The aim of this work was to compare pregnancy rates after cryopreservation of in vivo-produced ovine embryos with slow freezing or open pulled straw (OPS) vitrification method. Ewes were synchronized using intravaginal sponges containing 60 mg of medroxyprogesterone acetate for 14 d. Superovulation was performed using a total dose of 176 IU of ovine FSH (Ovagen), in 6 decreasing doses (i.m.) from Day 12 to 14 of treatment (Day 0 = sponge placing). Ewes were hand mated with 2 rams of proven fertility. Embryos were recovered 6 days after estrous detection by surgical procedure, evaluated under stereomicroscope, and randomly assigned to the cryopreservation treatments. Slow freezing was performed in D-PBS supplemented with 1.78 M ethylene glycol, 0.1 M sucrose, 4 mg mL-1 of BSA, and 20% serum. Embryos were loaded into 0.25-mL plastic straws and placed into a -7°C methanol bath chamber. After seeding embryos were cooled to -35°C at a rate of 0.5°C/min and then stored in liquid nitrogen. Thawing was performed by placing the straws in a 30°C water bath for 30 sec. Vitrification was performed by using the OPS method (Vajta et al. 1998) with minor modifications. Embryos were incubated in D-PBS supplemented with 1.78 M ethylene glycol, 1.3 M DMSO for 3 min and then transferred for 25 s in vitrification solution of D-PBS with 3.56 M ethylene glycol, 2.6 M DMSO, and 0.5 M sucrose, loaded in a 1 mL drop in the OPS, and immediately submerged into and stored in liquid nitrogen. Warming was performed in D-PBS plus 0.25 M sucrose for 5 min and then into D-PBS plus 0.15 M sucrose for another 5 min. Before embryo transfer, the presence of corpus luteum (CL) was detected by laparoscopic examination. One embryo per recipient was surgically transferred in the apical extreme of the uterine horn ipsilateral to the CL. Pregnancies were determined by ultrasonography 41 days after embryo transfer. Data were analyzed using the chi-square test. We found 47.8% pregnancy rate using slow freezing (11/23) and 43.5% pregnancy rate using OPS vitrification (10/23). Statistical differences were not detected (P = 0.09). We conclude that vitrification by OPS system, with minor modifications, is a suitable procedure for in vivo-produced ovine embryo cryopreservation.
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HALSTIAN, ANDRII, JURII VASHKURAK et OLGA KOSENKO. « STUDY OF THE OZONE REACTION OF BENZYL ACETATE AND ITS DERIVATIVES IN THE LIQUID PHASE ». Technologies and Engineering, no 3 (6 octobre 2022) : 17–25. http://dx.doi.org/10.30857/2786-5371.2022.3.2.
Texte intégralRésumé :
Purpose. Investigation of the kinetic regularities of the oxidation reaction of benzyl acetate and its derivatives by ozone in the liquid phase to determine the effect of alcohol on the ozonation of methylbenzenes by the methyl group.
Methodоlogy. A 20 ml glass vessel equipped with a magnetic stirrer was loaded sequentially with a calculated amount of toluene or benzyl acetate of sulfuric acid and 10 ml of acetic anhydride. After dissolution, the reaction components were loaded into a thermostatic glass column. The column was connected to a reflux condenser, the resulting solution was cooled to the required temperature and ozone-containing gas was passed through it. Oxidation was carried out to a given degree of substrate conversion. The process was controlled by gas-liquid chromatography. The ozone concentration in the gas phase was determined spectrophotometrically on an SF-46 spectrophotometer. The concentration of toluene and its derivatives in the solution was determined by gas-liquid chromatography on the chromatograph with a flame-ionization detector on the column with a length of 1 m and a diameter of 3.5 mm, filled with a carrier – INERTON-Super (0.16–0.2 mm), with a fixed phase “FFAP” applied to it in the amount of 5% of the mass of the carrier under the following conditions: evaporator temperature is between 503–533 K; carrier gas velocity (nitrogen) – 2.0 L•h-1; hydrogen velocity – 1.8 L•h-1; air velocity – 18 L•h-1. Thermostating was carried out in the temperature range of 363–448 K, the temperature rise was carried out by the program - 8оC/min.
Findings. The kinetic parameters of the ozonation reaction of benzylacetate and its derivatives in the liquid phase were studied. The rate constants of ozone reaction with benzyl acetate at different temperatures and the influence of the structure of substituents on its reactivity were determined. It is shown that the presence of electron-acceptor substituents increases the selectivity of oxidation along the side chain to 54%, and electron-donor – to a decrease of up to 8%. The kinetics of the reaction of ozone with benzyl acetate at a temperature of 293 K is described by a second-order equation that assumes a non-chain oxidation mechanism. At elevated temperatures, the chain consumption of ozone becomes noticeable due to its reaction with the products of destruction of the aromatic ring.
Originality. For the first time, the kinetics of the oxidation reaction of benzyl acetate and its substituted ozone in the liquid phase, which significantly affects the equilibrium concentration of alcohols in the oxidation of the corresponding methylbenzene. It was found that depending on the structure of acylated benzyl alcohol, the oxidation selectivity along the side chain is from 8 to 54%. The reaction rate constants are determined and the mechanism of ozonation of benzyl acetate is proposed, which will allow optimizing the parameters for the development of technological bases for the production of benzyl alcohol and its derivatives by ozonation of methylbenzenes in the liquid phase.
Practical value. The results are the basis for the development of low-temperature method for the synthesis of benzyl alcohols used in the production of active pharmaceutical ingredients.
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Hayes, A. R. « Liquid nitrogen-cooled devices ». Cryobiology 25, no 6 (décembre 1988) : 548. http://dx.doi.org/10.1016/0011-2240(88)90411-7.
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Chacón, L., M. C. Gómez, J. Jenkins, S. P. Leibo, G. Wirtu, B. L. Dresser et C. E. Pope. « 112 VIABILITY AND APOPTOSIS OF BOVINE FIBROBLASTS FROZEN IN A CONVENTIONAL ( - 20°C) OR LOW-TEMPERATURE ( - 80°C) FREEZER ». Reproduction, Fertility and Development 19, no 1 (2007) : 173. http://dx.doi.org/10.1071/rdv19n1ab112.
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Fibroblasts are commonly frozen in dimethyl sulfoxide (DMSO, 10% v/v) at a cooling rate of 1°C min−1 in cryo-containers placed in a low-temperature (−80°C) freezer (LTF) overnight before storage in liquid nitrogen (LN2). LTFs are not always available and cell viability may be altered by freezing at different cooling rates. Therefore, the purpose of the present study was to evaluate apoptosis and viability of bovine fibroblasts frozen at different cooling rates in a −80°C freezer or conventional −20°C freezer. Fibroblasts were generated from skin tissue collected from an adult female cow. Tissue was cut and cultured in DMEM for 7 to 10 days and passaged 2 or 3 times before being cryopreserved. Cells were frozen by one of 6 procedures; cells that were not frozen served as a control. To be frozen, cells were resuspended in DMEM + 10% FBS and 10% DMSO in 2-mL cryo-vials before being placed into freezing containers (Mr. Frosty, Nalgene). For groups 1 and 2, the container was placed in a −20°C freezer and cooled at ≈0.6°C min−1 to −7°C; ice formation was induced by seeding, after which cooling was continued at ≈0.6°C min−1 to −20°C. Vials in groups 1 and 2 were placed in LN2 after 1 h and 16 to 18 h, respectively. Group 3 and 4 vials were also cooled to −20°C at 0.6°C min, except that these samples were not seeded. After being held at −20°C for 16 to 18 h, group 3 vials were thawed; group 4 vials were stored in LN2. Vials in groups 5 and 6 were placed into a Mr. Frosty container and cooled at ≈1°C min−1 in a −80°C freezer. After being held at −80°C for 16 to 18 h, group 5 vials were thawed, and group 6 vials were placed into LN2. Group 1, 2, 3, and 4 vials were thawed in a 37°C water bath; group 5 and 6 vials were thawed in a 40°C water bath. Cell viabilities were quantified by using TB exclusion (TB) with microscopy. At least 20 000 cells from each group were thawed, and caspase 3, a key enzyme involved in apoptotic processes, was detected using a Caspase 3-FLICA apoptosis detection kit; propidium iodide-stained nuclei were assessed with cytometry (FCM) to determine viability (Table 1). Data were analyzed by ANOVA (P < 0.05). Although there were viability differences among groups, freezer type, seeding, holding time, and LN2 had no significant impact, as assessed by TB or FCM; however, no LN2 significantly increased the percentage of viable cells displaying apoptosis. In summary, bovine fibroblasts were successfully frozen in a conventional (−20°C) freezer before storage in LN2. Table 1. Viability and apoptosis of bovine fibroblasts frozen at −20°C or −80°C
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Coutinho, A. R. S., A. B. Nascimeto, C. M. Mendes, R. Simoes, C. F. Lucio, M. L. Z. Dagli et M. E. O. A. Assumpcao. « 82 EVALUATION OF CELL DEATH IN CRYOPRESERVED MOUSE EMBRYOS ». Reproduction, Fertility and Development 17, no 2 (2005) : 191. http://dx.doi.org/10.1071/rdv17n2ab82.
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Cryopreservation of mammalian embryos is an important tool for the application of reproductive biotechnology. Recent evidence indicates that apoptosis may be important in determining the viability of cryopreserved embryos. Our goal was to detect apoptosis and characterize and quantify the embryonic cell death caused by cryopreservation. Mouse morulae were collected, selected, and separated into three groups: fresh, slow-freezing, and vitrification. In the slow-freezing procedure, embryos were exposed to 10% ethylene glycol (EG) for 10 min. After loading, the straws were placed into methanol at −7°C for 5 min, seeded and after 5 min cooled at 0.5°C/minute. After 10 minutes at −31°C, straws were plunged into and stored in liquid nitrogen. Slow-frozen straws were thawed in air for 10 s, and then immersed in a 25°C water bath for 20 s. Embryos were vitrified by exposing them to 10% and 20% EG for 5 min followed by 40% EG + 18% Ficoll + 10% sucrose (EFS) for 30 s and the 0.25-mL straws then plunged into and stored in liquid nitrogen. The vitrified straws were warmed by immersing them in 25°C water for 20 s. Cell membrane integrity was assessed by Hoechst and propidium iodide double staining (H/PI). Fresh and thawed embryos were scored (following IETS recommendations) and then fixed after 30 min in PBS + 10% FCS. Morphology and apoptosis were assessed with Haematoxylin-Eosin staining (HE) and by electron microscopy (MET). The number of Grade I embryos recovered after thawing was higher for slow-frozen embryos (61.5%) than vitrified embryos (29.5%). H/PI detected more membrane permeability in the vitrified embryos (69.7%), than in the slow-frozen (48.4%) or non-frozen (13.8%) groups (P < 0,05, Wilcoxon's test). Nuclear evaluation by HE revealed that vitrification and slow-freezing induced pyknosis and chromatin condensation. Mitotic pattern was observed in the fresh and slow-frozen group, but not in vitrification group suggesting that the embryos were either not randomly allocated to the groups or not-treated and fixed at the same age, or that vitrification changed the nuclear status of the embryos. HE staining revealed weakly staining cytoplasm and degenerated cells in the vitrification group (indicating oncosis), while in the slow-frozen group the presence of cytoplasmic condensation and eosinophilic structures indicated apoptosis. The ultrastructure examination confirmed the HE observations. In conclusion, the results demonstrated that staining with HE allows detection of oncosis and apoptosis in cryopreserved embryos. According to these data, vitrification caused more cellular injuries than slow-freezing, and oncosis was the predominant injury. It is important to point that specific molecular apoptosis tests must be performed to confirm these results. This work was supported by FAPESP 04/01252-4.
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Longsworth, R. C., et W. A. Steyert. « Technology for liquid-nitrogen-cooled computers ». IEEE Transactions on Electron Devices 34, no 1 (janvier 1987) : 4–7. http://dx.doi.org/10.1109/t-ed.1987.22879.
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Zani, Veronica, Danilo Pedron, Roberto Pilot et Raffaella Signorini. « Contactless Temperature Sensing at the Microscale Based on Titanium Dioxide Raman Thermometry ». Biosensors 11, no 4 (2 avril 2021) : 102. http://dx.doi.org/10.3390/bios11040102.
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The determination of local temperature at the nanoscale is a key point to govern physical, chemical and biological processes, strongly influenced by temperature. Since a wide range of applications, from nanomedicine to nano- or micro-electronics, requires a precise determination of the local temperature, significant efforts have to be devoted to nanothermometry. The identification of efficient materials and the implementation of detection techniques are still a hot topic in nanothermometry. Many strategies have been already investigated and applied to real cases, but there is an urgent need to develop new protocols allowing for accurate and sensitive temperature determination. The focus of this work is the investigation of efficient optical thermometers, with potential applications in the biological field. Among the different optical techniques, Raman spectroscopy is currently emerging as a very interesting tool. Its main advantages rely on the possibility of carrying out non-destructive and non-contact measurements with high spatial resolution, reaching even the nanoscale. Temperature variations can be determined by following the changes in intensity, frequency position and width of one or more bands. Concerning the materials, Titanium dioxide has been chosen as Raman active material because of its intense cross-section and its biocompatibility, as already demonstrated in literature. Raman measurements have been performed on commercial anatase powder, with a crystallite dimension of hundreds of nm, using 488.0, 514.5, 568.2 and 647.1 nm excitation lines of the CW Ar+/Kr+ ion laser. The laser beam was focalized through a microscope on the sample, kept at defined temperature using a temperature controller, and the temperature was varied in the range of 283–323 K. The Stokes and anti-Stokes scattered light was analyzed through a triple monochromator and detected by a liquid nitrogen-cooled CCD camera. Raw data have been analyzed with Matlab, and Raman spectrum parameters—such as area, intensity, frequency position and width of the peak—have been calculated using a Lorentz fitting curve. Results obtained, calculating the anti-Stokes/Stokes area ratio, demonstrate that the Raman modes of anatase, in particular the Eg one at 143 cm−1, are excellent candidates for the local temperature detection in the visible range.
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Leclerc, Julien, Benedict Isichei et Aaron T. Becker. « A Magnetic Manipulator Cooled With Liquid Nitrogen ». IEEE Robotics and Automation Letters 3, no 4 (octobre 2018) : 4367–74. http://dx.doi.org/10.1109/lra.2018.2863358.
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Josephs, Richard M., Ronald A. Flowers et Peter L. Young. « 4459823 Rotating liquid nitrogen cooled substrate holder ». Vacuum 35, no 1 (janvier 1985) : 56. http://dx.doi.org/10.1016/0042-207x(85)90081-8.
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