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81.
In this study, activated sludge bacteria from a conventional wastewater treatment process were induced to accumulate polyhydroxyalkanoates
(PHAs) under different carbon-nitrogen (C:N) ratios. As the C:N ratio increased from 20 to 140, specific polymer yield increased
to a maximum of 0.38 g of polymer/g of dry cell mass while specific growth yield decreased. The highest overall polymer production
yield of 0.11 g of polymer/g of carbonaceous substrate consumed was achieved using a C:N ratio of 100. Moreover, the composition
of polymer accumulated was dependent on the valeric acid content in the feed. Copolymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate)
[P(3HB-co-3HV)] was produced in the presence of valeric acid. The 3-hydroxyvalerate (3HV) mole fraction in the copolymer was
linearly related tovaleric content in the feed, which reached a maximum of 54% when valeric acid was used as sole carbon source.
When the 3HV U in the polymer increased from 0–54 mol%, the melting temperature decreased from 178° to 99°C. Thus, the composition,
and hence the mechanical properties, of the copolymer produced from activated sludge can be controlled by adjusting the mole
fraction of valeric acid in the feed medium. 相似文献
82.
Mannan Zubaer Ibna Adhikari Shyam Prasad Kim Hyongsuk Chua Leon 《Nonlinear dynamics》2020,99(4):3169-3196
Nonlinear Dynamics - This paper presents an in-depth and rigorous mathematical analysis of a family of nonlinear dynamical circuits whose only nonlinear component is a Chua Corsage Memristor (CCM)... 相似文献
83.
We consider two notions for the representations of convex cones G-representation and lifted-G-representation. The former represents a convex cone as a slice of another; the latter allows in addition, the usage of auxiliary
variables in the representation. We first study the basic properties of these representations. We show that some basic properties
of convex cones are invariant under one notion of representation but not the other. In particular, we prove that lifted-G-representation is closed under duality when the representing cone is self-dual. We also prove that strict complementarity
of a convex optimization problem in conic form is preserved under G-representations. Then we move to study efficiency measures for representations. We evaluate the representations of homogeneous
convex cones based on the “smoothness” of the transformations mapping the central path of the representation to the central
path of the represented optimization problem.
Research of the first author was supported in part by a grant from the Faculty of Mathematics, University of Waterloo and
by a Discovery Grant from NSERC. Research of the second author was supported in part by a Discovery Grant from NSERC and a
PREA from Ontario, Canada. 相似文献
84.
Kok Seng Chua. 《Mathematics of Computation》2005,74(251):1457-1470
Let be a primitive, real and even Dirichlet character with conductor , and let be a positive real number. An old result of H. Davenport is that the cycle sums are all positive at and this has the immediate important consequence of the positivity of . We extend Davenport's idea to show that in fact for , 0$"> for all with so that one can deduce the positivity of by the nonnegativity of a finite sum for any . A simple algorithm then allows us to prove numerically that has no positive real zero for a conductor up to 200,000, extending the previous record of 986 due to Rosser more than 50 years ago. We also derive various estimates explicit in of the as well as the shifted cycle sums considered previously by Leu and Li for . These explicit estimates are all rather tight and may have independent interests.
85.
The technique of ferromagnetic resonance at 23 GHz has been used to determine the first three anisotropy constants of pure Ni down to 4.2K. A temperature and orientation dependent linewidth has also been observed. 相似文献
86.
Marianne Gilbert Siavash Haghighat Soo Keow Chua Soo Yeng Ng 《Macromolecular Symposia》2006,233(1):198-202
A novel method for producing a plasticised PVC with increased porosity has been developed, by the use of an organic-inorganic hybrid. Silica was produced in situ from tetraethoxysilane via a hydrolytic sol-gel processing route. Tetrahydrofuran was used as co-solvent, and γ-glycidyloxypropyl-trimethoxysilane as coupling agent. The films produced were transparent, with moderate mechanical properties. A film containing 20% silica showed a 45% increase in water vapour permeability. 相似文献
87.
88.
Dr. Chun Kiang Chua Prof. Martin Pumera 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(36):12550-12562
The rise in global demand for crucial chemical compounds has driven immense research in the fundamental science of catalysis. Graphene and its derivatives (chemically modified graphene, CMGs) have recently emerged as a new class of heterogeneous catalyst that promises economically viable and greener routes to these compounds. Although CMGs possess unique catalytic properties, the actual active sites are often points of discussion. Current minimal understanding on the possible effects of metallic impurities on the electrocatalytic performances of these CMGs calls forth the need to raise awareness on possible metallic impurities misrepresenting the actual chemical catalytic performances of the CMGs. This Minireview highlights the latest advances in the application of CMGs as catalysts, with an emphasis on the possible effects of metallic impurities on CMG catalysis. 相似文献
89.
First-principles calculations show that [NH(3)] molecules play crucial roles as both activator for the break-up of B-H bond and supplier of protic H for the establishment of dihydrogen bonding, which could facilitate the dehydrogenation of Ca(NH(2)BH(3))(2)·2NH(3) or Mg(NH(2)BH(3))(2)·NH(3) occurring at lower temperatures compared to those of Ca(NH(2)BH(3))(2) and Mg(NH(2)BH(3))(2). Moreover, the calculations of Helmholtz Free energy and [NH(3)] molecule removal energy evidence that coordination between [NH(3)] and Mg cation is stronger than that between [NH(3)] and Ca cation; therefore, Mg(NH(2)BH(3))(2)·NH(3) will undergo directly dehydrogenation rather than deammoniation at lower temperatures. 相似文献
90.
Paul B. Huleatt Jacelyn LauSheena Chua Yun Lei TanHung Anh Duong Christina L.L. Chai 《Tetrahedron letters》2011,52(12):1339-1342
A concise, efficient and simple route to a series of bromoindole building blocks is described. The synthetic routes are highlighted by purification-free preparation of o-nitrocinnamate intermediates and clean, modified Cadogan indole syntheses. The scope of this indole synthesis has been explored and expanded through the use of a range of solvents and easily removable phosphine reagents. 相似文献