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1.
Danny E. Akin W. Herbert Morrison III Luanne L. Rigsby Franklin E. Barton II David S. Himmelsbach Kevin B. Hicks 《Applied biochemistry and biotechnology》2006,129(1-3):104-116
Information is presented on structure, composition, and response to enzymes of corn stover related to barriers for bioconversion
to ethanol. Aromatic compounds occurred in most tissue cell walls. Ferulic acid esterase treatment before cellulase treatment
significantly improved dry weight loss and release of phenolic acids and sugars in most fractions over cellulase alone. Leaf
fractions were considerably higher in dry weight loss and released sugars with esterase treatment, but stem pith cells gave
up the most phenolic acids. Results help identify plant fractions more appropriate for coproducts and bioconversion and those
more suitable as residues for soil erosion control. 相似文献
2.
Ethan D. Bloch 《Discrete and Computational Geometry》2006,35(2):311-328
In a 1967 paper, Banchoff stated that a certain type of polyhedral curvature,
that applies to all finite polyhedra, was zero at all vertices of an odd-dimensional polyhedral manifold; one then obtains
an elementary proof that odd-dimensional manifolds have zero Euler characteristic. In a previous paper, the author defined
a different approach to curvature for arbitrary simplicial complexes, based upon a direct generalization of the angle defect.
The generalized angle defect is not zero at the simplices of every odd-dimensional manifold. In this paper we use a sequence
based upon the Bernoulli numbers to define a variant of the angle defect for finite simplicial complexes that still satisfies
a Gauss-Bonnet-type theorem, but is also zero at any simplex of an odd-dimensional simplicial complex K (of dimension at least
3), such that χ(link(ηi, K)) = 2 for all i-simplices ηi of K, where i is an even integer such that 0 ≤ i ≤ n – 1. As a corollary, an elementary proof is given that any such simplicial
complex has Euler characteristic zero. 相似文献
3.
S. Akin S. Isikli F. Korkusuz M. Ungan A. Senkoylu 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(2):361-364
The aim of this study was to investigate the relationship between BMD and age at lumbar spine and proximal femur in Turkish
males. Two hundred ninety healthy males (aged 20-59 years) were investigated. BMD of the lumbar spine had its peak at ages
30-39, however, the peak for the proximal femur was between the ages of 20 and 29. There was a significant decrease in BMD
at proximal femur after these peak values with increasing age. In conclusion, there was a significant correlation between
age and the proximal femoral BMD in males and age has a strong predictive power on proximal femur BMD score.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
4.
We show that a theorem of Shchepin and Repovš concerning the smoothness of compacta follows from the theory of semicontinuous relations. 相似文献
5.
Covalent and noncovalent chemistries that are selective to single-walled carbon nanotubes of a particular electronic type have become increasingly important for electronic structure separation and on-chip modification of nanoelectronic devices. By monitoring transient Raman spectroscopy and photoluminescence (PL) during a reaction with 4-chlorobenzene diazonium in aqueous solution, evidence for a characteristic two-step mechanism with two distinct time constants is uncovered. A long-lived intermediate selectively and noncovalently binds and partially dopes the nanotube surface (tau = 2.4 min). A slower, covalent reaction is tracked using the time-dependent increase in the disorder mode in Raman (tau = 73 min). The transient Raman and PL data are well described using a series of two first-order reactions. The covalent bonding step can be deactivated by changing the structure of the surfactant adsorbed phase, further supporting the mechanism. 相似文献
6.
Desjardins A Flemming J Sternberg ED Dolphin D 《Chemical communications (Cambridge, England)》2002,(22):2622-2623
Protoporphyrin reacts with diazomethane to give pyrazolines which at long wavelength (approximately 630 nm) extrude nitrogen to give the corresponding cyclopropyl derivatives. 相似文献
7.
Badman ER Myung S Clemmer DE 《Journal of the American Society for Mass Spectrometry》2005,16(9):1493-1497
The folding pathways of gas-phase cytochrome c ions produced by electrospray ionization have been studied by an ion trapping/ion mobility technique that allows conformations to be examined over extended timescales (10 ms to 10 s). The results show that the +9 charge state emerges from solution as a compact structure and then rapidly unfolds into several substantially more open structures, a transition that requires 30-60 ms; over substantially longer timescales (250 ms to 10 s) elongated states appear to refold into an array of folded structures. The new folded states are less compact than those that are apparent during the initial unfolding. Apparently, unfolding to highly open conformations is a key step that must occur before +9 ions can sample more compact states that are stable at longer times. 相似文献
8.
The elasticity of the polyacrylamide (PAAm)-kappa carrageenan (κC) composite was determined as a function of (w/v-%) κC content at 40 °C. The gel composites studied contained various percentages (w/v-%) of κC. The elasticity of the swollen PAAm-κC composite was characterized by using the tensile testing technique. This study investigated the elasticity and the percolation threshold of PAAm-κC composite as a function of κC content. It is understood that the compressive elastic modulus decreases up to 1 (w/v-%) of κC and then increases at contents above 1(w/v-%) of κC. The critical exponent of elasticity y was determined between 1 and 1.6 (w/v-%) of κC and found to be 0.68. The observed elastic percolation threshold is consistent with the suggested values of the superelastic percolation network. 相似文献
9.
10.