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71.
A. Sulfrian M. Kapp Margaret D. Foster und E. V. Mills 《Fresenius' Journal of Analytical Chemistry》1933,95(1-3):105-107
Ohne Zusammenfassung 相似文献
72.
In situ ion beam sputter deposition and X‐ray photoelectron spectroscopy (XPS) of multiple thin layers under computer control for combinatorial materials synthesis 下载免费PDF全文
Thomas A. Wilson Anders J. Barlow Michael L. Foster Mariela Bravo Sanchez Jose F. Portoles Naoko Sano Peter J. Cumpson Ian W. Fletcher 《Surface and interface analysis : SIA》2017,49(1):18-24
Deposition of ultra‐thin layers under computer control is a frequent requirement in studies of novel sensors, materials screening, heterogeneous catalysis, the probing of band offsets near semiconductor junctions and many other applications. Often large‐area samples are produced by magnetron sputtering from multiple targets or by atomic layer deposition (ALD). Samples can then be transferred to an analytical chamber for checking by X‐ray photoelectron spectroscopy (XPS) or other surface‐sensitive spectroscopies. The ‘wafer‐scale’ nature of these tools is often greater than is required in combinatorial studies, where a few square centimetres or even millimetres of sample is sufficient for each composition to be tested. The large size leads to increased capital cost, problems of registration as samples are transferred between deposition and analysis, and often makes the use of precious metals as sputter targets prohibitively expensive. Instead we have modified a commercial sample block designed to perform angle‐resolved XPS in a commercial XPS instrument. This now allows ion‐beam sputter deposition from up to six different targets under complete computer control. Ion beam deposition is an attractive technology for depositing ultra‐thin layers of great purity under ultra‐high vacuum conditions, but is generally a very expensive technology. Our new sample block allows ion beam sputtering using the ion gun normally used for sputter depth‐profiling of samples, greatly reducing the cost and allowing deposition to be done (and checked by XPS) in situ in a single instrument. Precious metals are deposited cheaply and efficiently by ion‐beam sputtering from thin metal foils. Samples can then be removed, studied and exposed to reactants or surface treatments before being returned to the XPS to examine and quantify the effects. Copyright © 2016 The Authors Surface and Interface Analysis Published by John Wiley & Sons Ltd. 相似文献
73.
Lau RK Ménard M Okawachi Y Foster MA Turner-Foster AC Salem R Lipson M Gaeta AL 《Optics letters》2011,36(7):1263-1265
We report the first demonstration of cw wavelength conversion from the telecommunications band to the mid-IR (MIR) region via four-wave mixing in silicon nanowaveguides. We measure a parametric bandwidth of 748 nm by converting a 1636 nm signal to produce a 2384 nm idler and show continuously tunable wavelength conversion from 1792 to 2116 nm. This report indicates that the advantages of silicon photonics may be leveraged to create devices for a large range of MIR applications that require cw operation. 相似文献
74.
Enzymatic hydrolysis of ammonia-treated sugar beet pulp 总被引:2,自引:0,他引:2
Foster Brian L. Dale Bruce E. Doran-Peterson Joy B. 《Applied biochemistry and biotechnology》2001,91(1-9):269-282
Sugar beet pulp is a carbohydrate-rich coproduct generated by the table sugar industry. Beet pulp has shown promise as a feedstock
for ethanol production using enzymesto hydroly zepolymeric carbohydrates and engineered bacteria to ferment sugars to ethanol.
In this study, sugar beet pulp underwent an ammonia pressurization depressurization (APD) pretreatment in which the pulp was
exploded by the sudden evaporation of ammonia in a reactor vessel. APD was found to substantially increase hydrolysis efficiency
of the cellulose component, but when hemicellulose- and pectindegrading enzymes wereadded, treated pulp hydrolysis was no
better than the untreated control. 相似文献
75.
76.
Foster K.R. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》2000,28(1):15-23
This paper reviews thermal and nonthermal mechanisms of interaction between radiofrequency (RF) fields and biological systems, focusing on pulsed fields with high peak power but low duty cycle. Models with simplified geometry are used to illustrate the coupling between external electromagnetic fields and the body, and with cellular and subcellular structures. Mechanisms of interaction may be linear or nonlinear with field strength, and thermal or nonthermal. Each mechanism is characterized by a threshold field strength (below which no observable response is produced) and time constant of response. Several classes of nonthermal mechanisms of interaction are well established; however, the anticipated thresholds for producing observable effects are expected to be very high. The bioeffects literature contains many open questions, including many reports of effects that are not clearly interpretable in terms of the mechanisms discussed in this paper 相似文献
77.
Nigel L. Pickett Douglas F. Foster David J. Cole-Hamilton 《Journal of Crystal Growth》1997,170(1-4):476-479
The effect of pyridine addition upon the gas-phase reactions of hydrogen sulphide (H2S) with dimethylzinc (Me2Zn) in the presence of pyridine has been investigated and compared with results from reactions of H2S with Me2Cd. The deposits of ZnS which form have been analysed and consist of particles in the nanocrystalline size range of mainly the hexagonal phase. The average particle size within the deposits depends on both the concentration of pyridine in the gas phase and the temperature at which the reactants are mixed. Pyridine may bind through the lone pair of the nitrogen to surface metal atoms of growing particles, inhibiting further growth of the particle. 相似文献
78.
Sustainable Synthesis of Chiral Tetrahydrofurans through the Selective Dehydration of Pentoses 下载免费PDF全文
Robert W. Foster Dr. Christopher J. Tame Dr. Dejan‐Krešimir Bučar Prof. Helen C. Hailes Dr. Tom D. Sheppard 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(45):15947-15950
L ‐Arabinose is an abundant resource available as a waste product of the sugar beet industry. Through use of a hydrazone‐based strategy, L ‐arabinose was selectively dehydrated to form a chiral tetrahydrofuran on a multi‐gram scale without the need for protecting groups. This approach was extended to other biomass‐derived reducing sugars and the mechanism of the key cyclization investigated. This methodology was applied to the synthesis of a range of functionalized chiral tetrahydrofurans, as well as a formal synthesis of 3R‐3‐hydroxymuscarine. 相似文献
79.
Scott C. Radzinski Jeffrey C. Foster John B. Matson 《Macromolecular rapid communications》2016,37(7):616-621
Bottlebrush polymers are synthesized using a tandem ring‐opening polymerization (ROP) and ring‐opening metathesis polymerization (ROMP) strategy. For the first time, ROP and ROMP are conducted sequentially in the same pot to yield well‐defined bottlebrush polymers with molecular weights in excess of 106 Da. The first step of this process involves the synthesis of a polylactide macromonomer (MM) via ROP of d ,l ‐lactide initiated by an alcohol‐functionalized norbornene. ROMP grafting‐through is then carried out in the same pot to produce the bottlebrush polymer. The applicability of this methodology is evaluated for different MM molecular weights and bottlebrush backbone degrees of polymerization. Size‐exclusion chromatographic and 1H NMR spectroscopic analyses confirm excellent control over both polymerization steps. In addition, bottlebrush polymers are imaged using atomic force microscopy and stain‐free transmission electron microscopy on graphene oxide.
80.
Colin G. Foster 《Experimental Mechanics》1987,27(3):255-261
Experiments on the axial compression buckling of high-quality epoxy cylindrical shells with imposed dimpletype defects are
described. Additionally, a technique for the manufacture of high-quality epoxy conical shells which buckle at loads approaching
the classical critical load is presented. For both types of shells, prebuckling deformations have been monitored optically.
The sizes of defects determined from the optical examination when applied in the space-frame approach to shell buckling have
led to predicted knock-down factors which are remarkably consistent with measured knock-down factors (i.e., the ratio of actual
collapse to classical critical load). 相似文献