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31.
32.
Refurbishment of a used in‐vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source‐II ring 下载免费PDF全文
Toshiya Tanabe Harmanpreet Bassan Andrew Broadbent Peter Cappadoro John Escallier David Harder Charles Hetzel Dean Hidas Charles Kitegi Bernard Kosciuk Marco Musardo Johnny Kirkland 《Journal of synchrotron radiation》2017,24(5):919-924
The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS‐II. There were four in‐vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini‐gap undulator (MGU‐X25, to be renamed IVU18 for NSLS‐II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS‐II. At the time of construction, IVU18 was a state‐of‐the‐art undulator designed to be operated as a cryogenic permanent‐magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS‐II ring, the transition region was redesigned. The control system was also updated to NSLS‐II specifications. This paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning. 相似文献
33.
为改善壳聚糖对细胞的特异性吸附,采用水溶性碳二亚胺将生物活性短肽精氨酸-甘氨酸-天冬氨酸-丝氨酸(RGDS)固定到壳聚糖膜的表面,采用X射线光电子能谱检测固定多肽前后的壳聚糖膜表面,发现反应后壳聚糖膜表面氮元素含量增大,Nls和Cls曲线拟合谱中酰胺键增多,表明RGDS短肽已固定到壳聚糖膜的表面;人角膜缘上皮细胞体外培养实验表明,固定RGDS后壳聚糖膜的细胞黏附率有了明显提高,固定RGDS后的壳聚糖膜在角膜组织工程支架等方面有更好的应用潜力。 相似文献
34.
RE Tribble A Azhari HL Clark CA Gagliardi Y-W Lui AM Mukhamedzhanov A Sattaroy X Tang L Trache V Burjan J Cejpek V Kroha S Piskor J Vincour F Carstoiu 《Pramana》1999,53(3):585-594
S-factors for direct capture reactions can be found at astrophysical energies from asymptotic normalization coefficients which
provide the normalization of the tail of the overlap function. For example the overlap for 8B → 7Be+p defines the S-factor for 7Be (p, γ)8B. Peripheral transfer reactions offer a technique to determine these asymptotic normalization coefficients. As a test of
the technique, the 16O(3He, d)17F reaction has been used to determine asymptotic normalization coefficients for transitions to the ground and first excited
states of 17F. The S-factors for 16O(p, γ)17F calculated from these 17F → 16O+p asymptotic normalization coefficients are found to be in very good agreement with recent measurements. Following the same
technique, the 10B(7Be, 8B)9Be and 14N(7Be, 8B)13C reactions have been used to measure the asymptotic normalization coefficient for 7Be(p, γ)8B. This result provides an indirect determination of S
17(0). 相似文献
35.
Andrew J. Hetzel 《International Journal of Mathematical Education in Science & Technology》2013,44(4):488-491
This note could find classroom use in an introductory course on complex analysis. Using some of the most significant theorems from complex analysis, the main result provides a simple method for transforming many elementary functions (defined on the complex plane) into everywhere continuous functions that are differentiable only on a nowhere dense set. Accordingly, such continuous functions are termed ‘practically nowhere differentiable’. The twofold pedagogical value of this method is that (1) students can readily generate examples of everywhere continuous, practically nowhere differentiable functions that do not require any direct appeal to infinite series, and (2) the often dynamical difference between the behaviour of functions of a complex variable and functions of a real variable is showcased. 相似文献
36.
Characterization of the efficiency of microbore liquid chromatography columns by van Deemter and kinetic plot analysis 下载免费PDF全文
Terence Hetzel Denise Loeker Thorsten Teutenberg Torsten C. Schmidt 《Journal of separation science》2016,39(20):3889-3897
The efficiency of miniaturized liquid chromatography columns with inner diameters between 200 and 300 μm has been investigated using a dedicated micro‐liquid chromatography system. Fully porous, core–shell and monolithic commercially available stationary phases were compared applying van Deemter and kinetic plot analysis. The sub‐2 μm fully porous as well as the 2.7 μm core–shell particle packed columns showed superior efficiency and similar values for the minimum reduced plate heights (2.56–2.69) before correction for extra‐column contribution compared to normal‐bore columns. Moreover, the influence of extra‐column contribution was investigated to demonstrate the difference between apparent and intrinsic efficiency by replacing the column by a zero dead volume union to determine the band spreading caused by the system. It was demonstrated that 72% of the intrinsic efficiency could be reached. The results of the kinetic plot analysis indicate the superior performance of the sub‐2 μm fully porous particle packed column for ultra‐fast liquid chromatography. 相似文献
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Chen Q Huang Z Chen H Shapiro H Beckers J Hetzel FW 《Photochemistry and photobiology》2002,76(2):197-203
Photodynamic therapy (PDT) requires molecular oxygen during light irradiation to generate reactive oxygen species. Tumor hypoxia, either preexisting or induced by PDT, can severely hamper the effectiveness of PDT. Lowering the light irradiation dose rate or fractionating a light dose may improve cell kill of PDT-induced hypoxic cells but will have no effect on preexisting hypoxic cells. In this study hyperoxygenation technique was used during PDT to overcome hypoxia. C3H mice with transplanted mammary carcinoma tumors were injected with 12.5 mg/kg Photofrin and irradiated with 630 nm laser light 24 h later. Tumor oxygenation was manipulated by subjecting the animals to 3 atp (atmospheric pressure) hyperbaric oxygen or normobaric oxygen during PDT light irradiation. The results show a significant improvement in tumor response when PDT was delivered during hyperoxygenation. With hyperoxygenation up to 80% of treated tumors showed no regrowth after 60 days. In comparison, when animals breathed room air, only 20% of treated tumors did not regrow. To explore the effect of hyperoxygenation on tumor oxygenation, tumor partial oxygen pressure was measured with microelectrodes positioned in preexisting hypoxic regions before and during the PDT. The results show that hyperoxygenation may oxygenate preexisting hypoxic cells and compensate for oxygen depletion induced by PDT light irradiation. In conclusion, hyperoxygenation may provide effective ways to improve PDT efficiency by oxygenating both preexisting and treatment-induced cell hypoxia. 相似文献
39.
40.
Helmut F. Hetzel 《Mikrochimica acta》1971,59(1):54-56
Zusammenfassung Strontium bildet ein schwerlösliches Tripelsalz der Zusammensetzung K2SrNi(NO2)6, das zum Nachweis in der qualitativen Analyse herangezogen werden kann. Beim Mischen der Strontiumlösung mit einem Nickelsalz und Kaliumnitrit in Gegenwart eines Acetatpuffers entstehen alsbald hellbraune stark lichtbrechende Würfel. Barium gibt die gleiche Reaktion, Calcium nicht. In größerem Überschuß stört Calcium.
The analytical utilizability of nitrite-triple salts
Summary Strontium forms a difficultly soluble triple salt of the composition K2SrNi(NO2)6, which can be used for detection purposes in qualitative analysis. When the strontium solution is mixed with a nickel salt and potassium nitrite in the presence of an acetate buffer, light brown strongly refractive cubes appear at once. Barium gives an analogous reaction, but not calcium. Calcium interferes if present in large excess.相似文献