573 research outputs found
Enrichment and characterization of a bacteria consortium capable of heterotrophic nitrification and aerobic denitrification at low temperature
Nitrogen removal in wastewater treatment plants is usually severely inhibited under cold temperature. The present study proposes bioaugmentation using psychrotolerant heterotrophic nitrification-aerobic denitrification consortium to enhance nitrogen removal at low temperature. A functional consortium has been successfully enriched by stepped increase in DO concentration. Using this consortium, the specific removal rates of ammonia and nitrate at 10 degrees C reached as high as 3.1 mg N/(g SS h) and 9.6 mg N/ (g SS h), respectively. PCR-DGGE and clone library analysis both indicated a significant reduction in bacterial diversity during enrichment. Phylogenetic analysis based on nearly full-length 16S rRNA genes showed that Alphaproteobacteria. Deltaproteobacteria and particularly Bacteroidetes declined while Gammaproteobacteria (all clustered into Pseudomonas sp.) and Betaproteobacteria (mainly Rhodoferax ferrireducens) became dominant in the enriched consortium. It is likely that Pseudomonas spp. played a major role in nitrification and denitrification, while R. ferrireducens and its relatives utilized nitrate as both electron acceptor and nitrogen source. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000312926400021&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701Agricultural EngineeringBiotechnology & Applied MicrobiologyEnergy & FuelsSCI(E)EIPubMed31ARTICLE151-15712
Structure and mechanism of peptide-induced membrane pores
This thesis reports the studies of the structure and mechanism of peptide-induced membrane pores by antimicrobial peptide alamethicin and by a peptide named Baxalpha5, which is derived from Bax protein. Alamethicin is one of best known antimicrobial peptides, which are ubiquitous throughout the biological world. Bax-alpha5 peptide is the pore-forming domain of apoptosis regulator protein Bax, which activates pore formation on outer mitochondrial membrane to release cytochrome c to initiate programmed cell death. Both peptides as well as many other pore-forming peptides, induce pores in membrane, however the structure and mechanism of the pore formation were unknown.
By utilizing grazing angle x-ray diffraction, I was able to reconstruct the electron density profile of the membrane pores induced by both peptides. The fully hydrated multiple bilayers of peptide-lipid mixture on solid substrate were prepared in the condition that pores were present, as established previously by neutron in-plane scattering and oriented circular dichroism.
At dehydrated conditions, the inter bilayer distance of the sample shortened and the interactions between bilayers caused the membrane pores to become long-ranged correlated and formed a periodically ordered lattice of rhombohedral symmetry, so that x-ray diffraction can be applied. To help solving the phase problem of diffraction, a brominated lipid was used and multi-wavelength anomalous diffraction was performed below the bromine K-edge. The reconstructed electron density profiles unambiguously revealed that the alamethicin-induced membrane pore is of barrel-stave type, while the Bax-alpha5 induced pore is of lipidic toroidal (wormhole) type.
The underlying mechanism of pore formation was resolved by observing the time-dependent process of pore formation in vesicles exposed to Bax-alpha5 solutions, as well as the membrane thinning experiment. This demonstrated that Bax-alpha5 exhibited the same sigmoidal concentration dependence as alamethicin: below a threshold concentration, peptide only binds to membrane surface, and thins the membrane; when the concentration exceeds a critical value, pores are formed.
The structure and mechanism of peptide-induced membrane pores provide insight onto how alpha-pore-forming proteins and peptides interact with membrane. The results also suggest that formation of lipidic pores is the major mechanism for alpha-pore-forming proteins
Glueball Masses from Hamiltonian Lattice QCD
We calculate the masses of the , and glueballs from
QCD in 3+1 dimensions using an eigenvalue equation method for Hamiltonian
lattice QCD developed and described elsewhere by the authors. The mass ratios
become approximately constants in the coupling region ,
from which we estimate and
.Comment: 12 pages, Latex, figures to be sent upon reques
Improving the Lattice QCD Hamiltonian
Improvement of the Hamiltonian in lattice gauge theory is considered. We give
explicit expressions for classical improvement and discuss also quantum
corrections.Comment: 3 pages, Latex. Presented at Lattice 97: 15th International Symposium
on Lattice Field Theory, Edinburgh, Scotland, 22-26 Jul 1997, to appear in
Nucl. Phys. B(Proc. Suppl.
Residual Attention Network for Image Classification
In this work, we propose "Residual Attention Network", a convolutional neural
network using attention mechanism which can incorporate with state-of-art feed
forward network architecture in an end-to-end training fashion. Our Residual
Attention Network is built by stacking Attention Modules which generate
attention-aware features. The attention-aware features from different modules
change adaptively as layers going deeper. Inside each Attention Module,
bottom-up top-down feedforward structure is used to unfold the feedforward and
feedback attention process into a single feedforward process. Importantly, we
propose attention residual learning to train very deep Residual Attention
Networks which can be easily scaled up to hundreds of layers. Extensive
analyses are conducted on CIFAR-10 and CIFAR-100 datasets to verify the
effectiveness of every module mentioned above. Our Residual Attention Network
achieves state-of-the-art object recognition performance on three benchmark
datasets including CIFAR-10 (3.90% error), CIFAR-100 (20.45% error) and
ImageNet (4.8% single model and single crop, top-5 error). Note that, our
method achieves 0.6% top-1 accuracy improvement with 46% trunk depth and 69%
forward FLOPs comparing to ResNet-200. The experiment also demonstrates that
our network is robust against noisy labels.Comment: accepted to CVPR201
QCD_3 Vacum Wave Function
We investigate quantum chromodynamics in 2+1 dimensions () using
the Hamiltonian lattice field theory approach. The long wavelength structure of
the ground state, which is closely related to the confinement phenomenon, is
analyzed and its vacuum wave function is evaluated by means of the recently
developed truncated eigenvalue equation method. The third order estimations
show nice scaling for the physical quantities.Comment: 10 pages plus 3 figures, encoded with uufiles
- …