2,978 research outputs found
Janis-Newman-Winicour and Wyman solutions are the same
We show that the well-known most general static and spherically symmetric
exact solution to the Einstein-massless scalar equations given by Wyman is the
same as one found by Janis, Newman and Winicour several years ago. We obtain
the energy associated with this spacetime and find that the total energy for
the case of the purely scalar field is zero.Comment: 9 pages, LaTex, no figures, misprints corrected, to appear in Int. J.
Mod. Phys.
Alien Registration- Wyman, Gerald Keedwell S. (Canton, Oxford County)
https://digitalmaine.com/alien_docs/15687/thumbnail.jp
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CELF significantly reduces milling requirements and improves soaking effectiveness for maximum sugar recovery of Alamo switchgrass over dilute sulfuric acid pretreatment
BackgroundPretreatment is effective in reducing the natural recalcitrance of plant biomass so polysaccharides in cell walls can be accessed for conversion to sugars. Furthermore, lignocellulosic biomass must typically be reduced in size to increase the pretreatment effectiveness and realize high sugar yields. However, biomass size reduction is a very energy-intensive operation and contributes significantly to the overall capital cost.ResultsIn this study, the effect of particle size reduction and biomass presoaking on the deconstruction of Alamo switchgrass was examined prior to pretreatment by dilute sulfuric acid (DSA) and Co-solvent Enhanced Lignocellulosic Fractionation (CELF) at pretreatment conditions optimized for maximum sugar release by each pretreatment coupled with subsequent enzymatic hydrolysis. Sugar yields by enzymatic hydrolysis were measured over a range of enzyme loadings. In general, DSA successfully solubilized hemicellulose, while CELF removed nearly 80% of Klason lignin from switchgrass in addition to the majority of hemicellulose. Presoaking and particle size reduction did not have a significant impact on biomass compositions after pretreatment for both DSA and CELF. However, presoaking for 4 h slightly increased sugar yields by enzymatic hydrolysis of DSA-pretreated switchgrass compared to unsoaked samples, whereas sugar yields from enzymatic hydrolysis of CELF solids continued to increase substantially for up to 18 h of presoaking time. Of particular importance, DSA required particle size reduction by knife milling to <â2 mm in order to achieve adequate sugar yields by subsequent enzymatic hydrolysis. CELF solids, on the other hand, realized nearly identical sugar yields from unmilled and milled switchgrass even at very low enzyme loadings.ConclusionsCELF was capable of achieving nearly theoretical sugar yields from enzymatic hydrolysis of pretreated switchgrass solids without size reduction, unlike DSA. These results indicate that CELF may be able to eliminate particle size reduction prior to pretreatment and thereby reduce overall costs of biological processing of biomass to fuels. In addition, presoaking proved much more effective for CELF than for DSA, particularly at low enzyme loadings
Interior perfect fluid scalar-tensor solution
We present a new exact perfect fluid interior solution for a particular
scalar-tensor theory. The solution is regular everywhere and has a well defined
boundary where the fluid pressure vanishes. The metric and the dilaton field
match continuously the external solution.Comment: 8 pages, 3 figures, LaTe
Effects of jamming on non-equilibrium transport times in nano-channels
Many biological channels perform highly selective transport without direct
input of metabolic energy and without transitions from a 'closed' to an 'open'
state during transport. Mechanisms of selectivity of such channels serve as an
inspiration for creation of artificial nano-molecular sorting devices and
bio-sensors. To elucidate the transport mechanisms, it is important to
understand the transport on the single molecule level in the experimentally
relevant regime when multiple particles are crowded in the channel. In this
paper we analyze the effects of inter-particle crowding on the non-equilibrium
transport times through a finite-length channel by means of analytical theory
and computer simulations
Algorithmic construction of static perfect fluid spheres
Perfect fluid spheres, both Newtonian and relativistic, have attracted
considerable attention as the first step in developing realistic stellar models
(or models for fluid planets). Whereas there have been some early hints on how
one might find general solutions to the perfect fluid constraint in the absence
of a specific equation of state, explicit and fully general solutions of the
perfect fluid constraint have only very recently been developed. In this
article we present a version of Lake's algorithm [Phys. Rev. D 67 (2003)
104015; gr-qc/0209104] wherein: (1) we re-cast the algorithm in terms of
variables with a clear physical meaning -- the average density and the locally
measured acceleration due to gravity, (2) we present explicit and fully general
formulae for the mass profile and pressure profile, and (3) we present an
explicit closed-form expression for the central pressure. Furthermore we can
then use the formalism to easily understand the pattern of inter-relationships
among many of the previously known exact solutions, and generate several new
exact solutions.Comment: Uses revtex4. V2: Minor clarifications, plus an additional section on
how to turn the algorithm into a solution generalization technique. This
version accepted for publication in Physical Review D. Now 7 page
Nuclear Magnetic Resonance Spectrum of the Triphenylcarbonium Ion
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71188/2/JCPSA6-34-4-1460-1.pd
Paramagnetic Resonance Absorption in Some Organic Biradicals
Four compounds of the form 4,4âČâpolymethylenebistriphenylmethyl, one compound of the form (1,4âphenylene)bisdiarylmethyl, three compounds of the form (4,4âČâbiphenylene)bisdiarylmethyl, and one compound, 4,4âČâoxybistriphenylmethyl have been shown to possess unpaired electrons by paramagnetic resonance absorption. The resonance spectra of 0.01 M solutions of these compounds in benzene exhibit a hyperfine structure arising from a spherically symmetrical contribution of the magnetic dipole interaction between the unpaired electron and the nuclear magnetic moments of the hydrogen atoms. The gâfactors for the compounds investigated in the first three classes were found to be 2.0025±0.0004 and 2.0031±0.0004 for the last compound. Such a close approach of the gâfactor to the free electron value plus the sharpness of the hyperfine structure lines indicates that the anisotropic contributions of the spinâorbit interaction, which would normally lift the degeneracy of the triplet state, are averaged out by the tumbling of the molecules.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70965/2/JCPSA6-25-4-697-1.pd
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