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111.
Herein, we describe the controlled growth of 1 dimensional germanium nanostructures from high aspect ratio nanowires (>10 microns in length) to shorter aspect nanorods (100 nm in length) via a simple pyrolysis method. The synthetic route involves the thermal decomposition of selected germanium precursors by dropping a solution in a high boiling point solvent directly onto a pre-heated Si wafer in the presence of a copper source under inert conditions. 相似文献
112.
Lawford Hugh G. Rousseau Joyce D. Tolan Jeffrey S. 《Applied biochemistry and biotechnology》2001,91(1-9):133-146
Iogen Corporation of Ottawa, Canada, has recently built a 50 t/d biomass-to-ethanol demonstration plant adjacent to its enzyme
production facility. Iogen has partnered with the University of Toronto to test the C6/C5 cofermentation performance characteristics
of National Renewable Energy Laboratory's metabolically engineered Zymomonas mobilis using its biomass hydrolysates. In this study, the biomass feedstock was an agricultural waste, namely oat hulls, which was
hydrolyzed in a proprietary two-stage process involving pretreatment with dilute sulfuric acid at 200–250°C, followed by cellulase
hydrolysis. The oat hull hydrolysate (OHH) contained glucose, xylose, and arabinose in a mass ratio of about 8:3:0.5. Fermentation
media, prepared from diluted hydrolysate, were nutritionally amended with 2.5 mL/L of corn steep liquor (50% solids) and 1.2
g/L of diammonium phosphate. The estimated cost for large-scale ethanol production using this minimal level of nutrient supplementation
was 4.4c/gal of ethanol. This work examined the growth and fermentation performance of xyloseutilizing, tetracycline-resistant,
plasmid-bearing, patented, recombinant Z. mobilis cultures: CP4:pZB5, ZM4:pZB5, 39676:pZB4L, and a hardwood prehydrolysate-adapted variant of 39676:pZB4L (designated asthe
“adapted” strain). In pH-stat batch fermentations with unconditioned OHH containing 6% (w/v) glucose, 3% xylose, and 0.75%
acetic acid, rec Zm ZM4:pZB5 gave the best performance with a fermentation time of 30h, followed by CP4:pZB5 at 48h, with
corresponding volumetric productivities of 1.4 and 0.89 g/(L·h), respectively. Based on the available glucose and xylose,
the process ethanol yield for both strains was 0.47 g/g (92% conversion efficiency). At 48 h, the process yield for rec Zm
39676:pZB4L and the adapted strain was 0.32 and 0.34 g/g, respectively. None of the test strains was able to fermentarabinose.
Acetic acid tolerance appeared to be a major determining factor in cofermentation performance. 相似文献
113.
Chung‐Der Chen Andrew P. J. Brunskill Stan S. Hall Roger A. Lalancette Hugh W. Thompson 《Acta Crystallographica. Section C, Structural Chemistry》2000,56(9):1148-1151
α‐Oxobenzeneacetic (phenylglyoxylic) acid, C8H6O3, adopts a transoid dicarbonyl conformation in the solid state, with the carboxyl group rotated 44.4 (1)° from the nearly planar benzoyl moiety. The heterochiral acid‐to‐ketone catemers [O?O = 2.686 (3) and H?O = 1.78 (4) Å] have a second, longer, intermolecular O—H?O contact to a carboxyl sp3 O atom [O?O = 3.274 (2) and H?O = 2.72 (4) Å], with each flat ribbon‐like chain lying in the bc plane and extending in the c direction. In α‐oxo‐2,4,6‐trimethylbenzeneacetic (mesitylglyoxylic) acid, C11H12O3, the ketone is rotated 49.1 (7)° from planarity with the aryl ring and the carboxyl group is rotated a further 31.2 (7)° from the ketone plane. The solid consists of chiral conformers of a single handedness, aggregating in hydrogen‐bonding chains whose units are related by a 31 screw axis, producing hydrogen‐bonding helices that extend in the c direction. The hydrogen bonding is of the acid‐to‐acid type [O?O = 2.709 (6) and H?O = 1.87 (5) Å] and does not formally involve the ketone; however, the ketone O atom in the acceptor molecule has a close polar contact with the same donor carboxyl group [O?O = 3.005 (6) and H?O = 2.50 (5) Å]. This secondary hydrogen bond is probably a major factor in stabilizing the observed cisoid dicarbonyl conformation. Several intermolecular C—H?O close contacts were found for the latter compound. 相似文献
114.
Hugh W. Thompson Roger A. Lalancette Andrew P. J. Brunskill 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(5):632-633
The hemihydrate of the title diketo acid, C24H36O4·0.5H2O, forms hydrogen‐bonded carboxyl dimers related by a C2 axis at crystallographic sites on the a and b edges of the chosen cell [O?O = 2.643 (7) and 2.716 (7) Å]. The ketone ends of the molecules approach each other at sites near (½,½,½), (½,0,½), (0,0,½) and (0,½,½) in an interleaved arrangement incorporating partial‐occupancy water hydrogen bonded to the B‐ring ketone. 相似文献
115.
Shulin Zhao Chandan Prasad Hugh J. F. Robertson Y.-M. Liu 《Analytical and bioanalytical chemistry》2001,369(3-4):220-224
A capillary electrophoresis (CE) method with laser induced fluorescence (LIF) detection is described for quantification of enterostatin (Val-Pro-Asp-Pro-Arg), a pentapeptide involved in appetite regulation and insulin secretion. Enterostatin and two other pentapeptides belonging to the enterostatin family (i.e. Ala-Pro-Gly-Pro-Arg and Val-Pro-Gly-Pro-Arg) were well separated from each other. The peptides were fluorescently tagged with naphthalene-2,3- dicarboxaldehyde (NDA) and separated by micellar electrokinetic chromatography (MEKC) in the presence of methanol as an organic modifier. Coupled with LIF detection, the method had a detection limit of 4.8 × 10–6 M for enterostatin. The relative standard deviation was to be 4.0% from five determinations of enterostatin at 37.2 μM in a human cerebrospinal fluid (CSF) sample. Twenty-three human CSF samples were analyzed. The level of enterostatin ranged from 24 μM to 51 μM with a mean (± SEM) value of 41.7 ± 2.0 μM. 相似文献
116.
Alan Barcon Andrew P. J. Brunskill Roger A. Lalancette Hugh W. Thompson Allan J. Miller 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(3):325-328
The crystal structure of (±)-4-oxo-1,2,3,4-tetrahydronaphthalene-2-carboxylic acid (C11H10O3) involves projection of the carboxyl group nearly orthogonal to the aromatic plane and hydrogen bonding of the acid groups by centrosymmetric pairing across the a edge and the center of the chosen cell [O⃛O = 2.705 (2) Å]. Intermolecular C—H⃛O=C close contacts to translationally related molecules are found for both the ketone (2.55 Å) and the acid (2.67 Å). In (±)-1-oxo-1,2,3,4-tetrahydronaphthalene-2-acetic acid (C12H12O3), the aggregation involves centrosymmetric carboxyl dimers mutually hydrogen bonded across the bc face and the a edge of the chosen cell [O⃛O = 2.674 (2) Å]. A 2.60 Å close C—H⃛O=C contact is found to the carboxyl group of centrosymmetrically related molecule. 相似文献
117.
Lithuanian Mathematical Journal - In this paper, we propose a new method of upper bounds for the number of integer polynomials of the fourth degree with a given discriminant. By direct calculation... 相似文献
118.
119.
R. Alan Aitken Ian Gosney Hugh Farries Michael H. Palmer Isobel Simpson John I.G. Cadogan Edward J. Tinley 《Tetrahedron》1984,40(13):2487-2503
The ease of formation of aziridine and/or epoxides from a series of bicyclic olefins, where distant sulphonyl groups are present, is very variable. There is some correlation between reactivity of the vinyl group and its π-ionisation potential which is high in the present molecules relative to comparison olefins. This increase is thought to be due to the presence of orbital interactions through bonds and/or through space between the sulphone group and the double bond, making the latter electron deficient. The ionisation potentials were determined by UV-photoelectron spectroscopy and the assignments made by recourse to ab initio configuration interaction methods. 相似文献
120.
David Hands Hugh Marley Stephen J. Skittrall Stanley H. B. Wright Thomas R. Verhoeven 《Journal of heterocyclic chemistry》1986,23(5):1333-1337
An economic synthesis of 3-hydroxymethyldibenzo[b,f]thiepin 5,5-dioxide, a novel prostaglandin antagonist, is described. The key step in the synthesis is the formation of a carboxyphenylacetic acid by carboxylation of a toluic acid dianion, followed by cyclisation to the tricyclic ketone. Readily available starting materials are used in the synthesis and conditions have been found at each stage to give pure intermediates, requiring little purification, in high yield. 相似文献