bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape Optimization of an Organic Rankine Cycle Radial Turbine Nozzle
Authors: Pasquale David , Ghidoni Antonio , Rebay Stefano
Published: March 2013

During the last decade, organic Rankine cycle (ORC) turbogenerators have become very attractive for the exploitation of low-temperature heat sources in the small to medium power range. Organic Rankine cycles usually operate in thermodynamic regions characterized by high pressure ratios and strong real-gas effects in the flow expansion, therefore requiring a nonstandard turbomachinery design. In this context, due to the lack of experience, a promising approach for the design can be based on the intensive use of computational fluid dynamics (CFD) and optimization procedures to investigate a wide range of possible configurations. In this work, an advanced global optimization strategy is coupled with a state-of-the-art CFD solver in order to assist in the design of ORC turbines. In particular, a metamodel assisted genetic algorithm, based on the so-called `off-line trained’ metamodel technique, has been employed. The numerical solutions of the two-dimensional (2D) Euler equations are computed with the in-house built code zFlow. The working fluid is toluene, whose thermodynamic properties are evaluated by an accurate equation of state, available in FluidProp. The computational grids created during the optimization process have been generated through a fully automated 2D unstructured mesh algorithm based on the advancing-Delaunnay strategy. The capability of this procedure is demonstrated by improving the design of an existing one-stage impulse radial turbine, where a strong shock appears in the stator channel due to the high expansion ratio. The goal of the optimization is to minimize the total pressure losses and to obtain a uniform axisymmetric stream at the stator discharge section, in terms of both the velocity magnitude and direction of the flow.
Enhancement of the Electrical Efficiency of Commercial Fuel Cell Units by Means of an Organic Rankine Cycle: A Case Study
Authors: De Servi Carlo , Campanari Stefano , Tizzanini Alessio , Pietra Claudio
Published: March 2013

Among the various fuel cell (FC) systems, molten carbonate fuel cells (MCFC) are nowadays one of the most promising technologies, thanks to the lower specific costs and a very high electrical efficiency (net low heating value (LHV) electric efficiency in the range 45%–50% at MWel scale using natural gas as fuel). Despite this high performance, MCFC rejects to the ambient almost half of the fuel energy at about 350–400 °C. Waste heat can be exploited in a recovery Rankine cycle unit, thereby enhancing the electric efficiency of the overall system. Due to the temperature of the heat source and the relatively small power capacity of MCFC plants (from few hundred kWel to 10 MWel), steam Rankine cycle technology is uneconomical and less efficient compared to that of the organic Rankine cycle (ORC). The objective of this work is to verify the practical feasibility of the integration between a MCFC system (topping unit) and an ORC turbogenerator (bottoming unit). The potential benefits of the combined plant are assessed in relation to a commercial MCFC stack. In order to identify the most suitable working fluids for the ORC system, organic substances are considered and compared. The figure of merit is the maximum net power of the overall system. Finally, the economical benefits of the integration are determined by evaluating the levelized cost of electricity (LCOE) of the combined plant, with respect to the standalone MCFC system. In order to assess the economic viability of the bottoming power unit, two cases are considered. In the first one, the ORC power output is approximately 500 kWel; in the latter, about 1 MWel. Results show that the proposed solution can increase the electrical power output and efficiency of the plant by more than 10%, well exceeding 50% overall electrical efficiency. In addition, the LCOE of the combined power plant is 8% lower than the standalone MCFC system.
A Multipoint Flux Approximation of the Steady-State Heat Conduction Equation in Anisotropic Media
Authors: Salama Amgad , Sun Shuyu , El Amin M. F.
Published: March 2013

In this work, we introduce multipoint flux (MF) approximation method to the problem of conduction heat transfer in anisotropic media. In such media, the heat flux vector is no longer coincident with the temperature gradient vector. In this case, thermal conductivity is described as a second order tensor that usually requires, at least, six quantities to be fully defined in general three-dimensional problems. The two-point flux finite differences approximation may not handle such anisotropy and essentially more points need to be involved to describe the heat flux vector. In the framework of mixed finite element method (MFE), the MFMFE methods are locally conservative with continuous normal fluxes. We consider the lowest order Brezzi–Douglas–Marini (BDM) mixed finite element method with a special quadrature rule that allows for nodal velocity elimination resulting in a cell-centered system for the temperature. We show comparisons with some analytical solution of the problem of conduction heat transfer in anisotropic long strip. We also consider the problem of heat conduction in a bounded, rectangular domain with different anisotropy scenarios. It is noticed that the temperature field is significantly affected by such anisotropy scenarios. Also, the technique used in this work has shown that it is possible to use the finite difference settings to handle heat transfer in anisotropic media. In this case, heat flux vectors, for the case of rectangular mesh, generally require six points to be described.
Effect of Nanostructured Roughness on Evaporating Thin Films in Microchannels for Wenzel and Cassie–Baxter States
Authors: Zhao Jun-Jie , Duan Yuan-Yuan , Wang Xiao-Dong , Wang Bu-Xuan
Published: March 2013

A model based on the augmented Young–Laplace equation and kinetic theory was developed to describe the nanostructured roughness effects on an extended evaporating meniscus in a microchannel for Wenzel and Cassie–Baxter states. The roughness geometries were analytically related to the disjoining pressure, slip length and thermal resistance across the roughness layer. The results show that the equivalent Hamaker constant and adsorbed film thickness increase with nanopillar height for Wenzel state. Thus, the spreading and wetting properties of the evaporating thin film increase with roughness for Wenzel state, leading to an elongated thin film and enhanced heat transfer rate compared to a flat hydrophilic surface. The equivalent Hamaker constant and disjoining pressure effect decrease with increasing nanopillar height for Cassie–Baxter state. The system wettability, thin film length and heat transfer rate increase with increasing slip length and with decreasing roughness for Cassie–Baxter state. A smaller roughness coexisting with a larger slip length on rough surfaces for Cassie–Baxter state results in a much higher heat transfer rate relative to a flat surface.
Resolved Order of Scattering for the Solution of Radiative Transfer Equation
Authors: Wang Liangyu , Hall Robert J. , Colket Meredith B.
Published: March 2013

The solution of the radiative transfer equation (RTE) becomes complicated when the participating medium is scattering and/or the boundary walls are reflecting. To reduce the complexity, the resolved order of scattering (ROS) formulation described in this paper separates the radiative intensities being solved by RTE into a series of intensities corresponding to different orders of the scattering and reflection events. The resulting equation of transfer for each order of radiative intensity is not only much simpler to solve but also represents the physical scattering/reflection processes that are hidden in the original full RTE. The ROS formulation provides a mathematically rigorous and elegant means of solving RTE for strong scattering media with or without reflecting boundaries. Sample calculations are presented for a droplet-laden, 3D enclosure with strong anisotropic scattering.
Proposal of a Solar-Coal Power Plant on Off-Design Operation
Authors: Zhao Yawen , Hong Hui , Jin Hongguang
Published: March 2013

In a solar hybrid system, the intermittent solar radiation seriously effects the solar-to-electricity conversion. In this paper, the energy-level mechanism between the concentrated solar heat and the thermal cycle was discussed. The system analysis was taken on a 200 MW coal-fired power plant hybridized with solar heat at approximately 300 °C, where the middle-temperature solar thermal energy was used to preheat the feed water before entering the boiler. With changing solar radiation in typical days, the solar share, the work output and the net solar-to-electricity efficiency of this solar hybrid system were evaluated. The net solar-to-electricity efficiency would be increased by 3–7% points compared to that in a solar-only power plant. An off-design parallel configuration of this hybrid system was proposed, achieving the net annual solar-to-electricity efficiency of 18%. It would expected to be an attractive approach to develop the scale-up mid-temperature solar thermal power technology in the short and midterm.
Reconstruction of Three-Dimensional Gas Metal Arc Weld Pool Surface From Reflected Laser Pattern
Authors: Ma XiaoJi , Zhang YuMing
Published: March 2013

A system has been developed to measure the three-dimensional weld pool surface geometry in the gas metal arc welding (GMAW) process. It utilizes the specular nature of the weld pool surface by projecting a five-line laser pattern onto the surface and imaging its reflection. Specifically, the laser reflection is intercepted by an imaging plane and captured using a high speed camera. The reflected pattern is used to reconstruct the weld pool surface based on the law of reflection. Two reconstruction algorithms, referred to as center-points reconstruction and piece-wise weld pool surface reconstruction algorithm, are applied to sequentially reconstruct the weld pool height and three-dimensional surface geometry. Reconstructions has been conducted using simulated weld pool surface to provide a method to compare the reconstruction result with a known surface and evaluate the reconstruction accuracy. It is found that the proposed method is capable of reconstructing weld pool surface with acceptable accuracy. The height error of reconstructed center-points is less than 0.1 mm and the error of estimated weld pool boundary is less than 10%. Reconstruction results from images captured in welding experiments are also demonstrated.
Feasibility of Supercritical Carbon Dioxide Based Metalworking Fluids in Micromilling
Authors: Supekar S. D. , Gozen B. A. , Bediz B. , Ozdoganlar O. B. , Skerlos S. J.
Published: March 2013

This article investigates the feasibility of using supercritical carbon dioxide based metalworking fluids (scCO2 metalworking fluids (MWFs)) to improve micromachinability of metals. Specifically, sets of channels were fabricated using micromilling on 304 stainless steel and 101 copper under varying machining conditions with and without scCO2 MWF. Burr formation, average specific cutting energy, surface roughness, and tool wear were analyzed and compared. Compared to dry machining, use of scCO2 MWF reduced burr formation in both materials, reduced surface roughness by up to 69% in 304 stainless steel and up to 33% in 101 copper, tool wear by up to 20% in 101 copper, and specific cutting energy by up to 87% in 304 stainless steel and up to 40% in 101 copper. The results demonstrate an improvement in micromachinability of the materials under consideration and motivate future investigations of scCO2 MWF-assisted micromachining to reveal underlying mechanisms of functionality, as well as to directly compare the performance of scCO2 MWF with alternative MWFs appropriate for micromachining.
A Study on Stress Corrosion Crack of Thick-Walled Elbow in Manifold for Acid Fracturing
Authors: Xie Yong-Jin , Zhang Hong , Liu Shuai , Yang Peng , Luo Xi
Published: March 2013

Acid fracturing, with a pumping pressure up to 140 MPa for fractural liquid injection, is commonly used in enhanced oil recovery. Subjected to severely high hoop stress, stress corrosion cracking (SCC) often occurs at cracks inside manifold elbows which are due to acid corrosion and fracturing propping agent erosion. To avoid the occurrence of SCC, it is necessary to establish a substantial understanding of the fracture strength of thick-walled elbow, including the stress state distribution in elbow and SCC properties of elbow material. Base on the hoop stress calculation for thin wall straight pipe, a formula for hoop stress of thick-walled elbow is derived and also verified with finite element method (FEM). This is accomplished by introduce curvature factor and wall thickness factor into the formula. Furthermore, the critical stress intensity factor, KISCC, is determined subsequently in simulated acid fracturing corrosion condition. However, part of the considerable contribution of this work is to scale the critical crack depth. A simplified hoop stress formula proposed in this paper can be used in design of elbow wall thickness and strength evaluation. The established critical crack depth calculation formula can be applied to safety assessment of elbows with initial erosion cracks. The proposed method has been proved to be a simple and useful method to calculate the stress and fractural strength of thick-walled elbow.
Advanced Dual-Axis Backtracking Improves Output While Reducing Project Costs—Technology That Produces the Best Project Internal Rate of Return in the Solar Industry
Authors: Oosting Kenneth W. , Green James E. , Rutherford Reid , Snook Amy J. , Keele Dustin
Published: March 2013

This paper reviews the results of 3 years of research and development in optimizing solar project internal rate of return (IRR) through various solar mounting strategies, including fixed-mount, single-axis, and dual-axis tracking. Various tracking algorithms are explored. The results of the research show that shadowing from adjacent photovoltaic (PV) arrays, as well as horizon clouds, significantly impact power output in traditional mounting architectures, but that innovative tracking algorithms and array shape can reduce the negative impact of shadowing. These innovations produce greater power output while reducing project costs and substantially increasing project IRR.
Characteristics of Transient Electroosmotic Flow in Microchannels With Complex-Wavy Surface and Periodic Time-Varying Electric Field
Authors: Cho Ching-Chang , Chen Chieh-Li , Chen Cha'o-Kuang
Published: March 2013

A numerical investigation is performed into the flow characteristics of the electroosmotic flow induced within a microchannel with a complex-wavy surface by a time-varying periodic electric field. The simulations focus specifically on the effects of the Strouhal number of the periodic electric potential, the amplitude of the periodic electric potential, the amplitude of the complex-wavy surface, and the waveform geometry. The results show that under steady-time periodic conditions, the flow pattern induced within the microchannel varies over the course of the oscillation period. In particular, it is shown that a flow recirculation structure is generated in the trough region of the wavy surface as the applied electric field falls to zero if the amplitude of the wavy surface exceeds a certain threshold value. In addition, it is shown that the phases of the electric field and electroosmotic velocity near the wall surface are almost identical. However, a phase shift exists between the electric field and the bulk flow velocity in the central region of the channel; particularly at larger values of the Strouhal number. Finally, it is shown that the velocity profile near the wavy surface is more sensitive to changes in the waveform geometry than that in the center of the channel. Overall, the simulation results presented in the study provide a useful source of reference for the development of new microfluidic systems incorporating microchannels with complex-wavy surfaces.
Position-Dependent Multibody Dynamic Modeling of Machine Tools Based on Improved Reduced Order Models
Authors: Law Mohit , Phani A. Srikantha , Altintas Yusuf
Published: March 2013

Dynamic response of a machine tool structure varies along the tool path depending on the changes in its structural configurations. The productivity of the machine tool varies as a function of its frequency response function (FRF) which determines its chatter stability and productivity. This paper presents a computationally efficient reduced order model to obtain the FRF at the tool center point of a machine tool at any desired position within its work volume. The machine tool is represented by its position invariant substructures. These substructures are assembled at the contacting interfaces by using novel adaptations of constraint formulations. As the tool moves to a new position, these constraint equations are updated to predict the FRFs efficiently without having to use computationally costly full order finite element or modal models. To facilitate dynamic substructuring, an improved variant of standard component mode synthesis method is developed which automates reduced order determination by retaining only the important modes of the subsystems. Position-dependent dynamic behavior and chatter stability charts are successfully simulated for a virtual three axis milling machine, using the substructurally synthesized reduced order model. Stability lobes obtained using the reduced order model agree well with the corresponding full-order system.
Numerical Simulation of Fluid Flow Past an Oscillating Triangular Cylinder in a Channel
Authors: Alawadhi Esam M.
Published: March 2013

The structure of laminar incompressible flow in a two-dimensional horizontal channel past a triangular cylinder undergoing vertical oscillating motion is simulated using the finite element method. The oscillating motion is carried out for a fixed Reynolds number equal to 100 and dimensionless oscillating amplitudes of 0.125, 0.25, 0.5, and 1, while the dimensionless forced oscillation frequencies are chosen from St/4 to 4 St, where St is the natural Strouhal number of a stationary triangular cylinder. The arbitrary Lagrangian–Eulerian kinematics is utilized to simulate the oscillating motion. The present problem is first solved for a stationary triangular cylinder to obtain the natural Strouhal number. Then, the fluid dynamics for an oscillating triangular cylinder are solved in terms of instantaneous drag and lift, mean of drag, and root mean square (RMS) of lift coefficients. Detailed illustrations of flow streamlines and vortices contours are presented. The results indicate that when the oscillating frequency is equal to the natural Strouhal number of the stationary cylinder, the RMS of lift coefficient reaches its maximum and the oscillating amplitude has no effect at high oscillating frequency.
Stability of Dean Flow Between Two Porous Concentric Cylinders With Radial Flow and a Constant Heat Flux at the Inner Cylinder
Authors: Deka R. K. , Paul A.
Published: March 2013

A linear analysis for the instability of viscous flow between two porous concentric circular cylinders driven by a constant azimuthal pressure gradient is presented when a radial flow through the permeable walls of the cylinders is present. In addition, a constant heat flux at the inner cylinder is applied. The linearized stability equations form an eigenvalue problem, which is solved by using the classical Runge–Kutta–Fehlberg scheme combined with a shooting method, which is termed the unit disturbance method. It is found that for a given value of the constant heat flux parameter N, even for a radially weak outward flow, there is a strong stabilizing effect and the stabilization is greater as the gap between the cylinders increases. However, in the presence of a weak inward flow for a wider gap, the constant heat flux has no role on the onset.
Identification and Modeling of Process Damping in Milling
Authors: Tunc L. T. , Budak E.
Published: March 2013

In this study, a practical identification method for process damping is presented for milling, and the information obtained from identification is used for modeling purposes. In the proposed approach, the process-damping coefficients in x and y directions are identified directly from the experimental stability limits. Then, they are used in identification of the indentation constant through energy balance formulation. The identified indentation constant is further used in modeling of process damping and estimation of stability limit for different cutting conditions and tool geometries. Milling tools with two different types of flank geometries, namely, planar and cylindrical, are considered in this study. The predictions are verified by time-domain simulations and experimental results. It is shown that the presented method can be used for identification and modeling of process damping in milling to determine chatter-free cutting depths at relatively low cutting speeds.
Uncertainty Analysis of Solid-Liquid-Vapor Phase Change of a Metal Particle Subject to Nanosecond Laser Heating
Authors: Peng Hao , Zhang Yuwen , Pai P. Frank
Published: March 2013

The effects of the uncertainties of various parameters, including the laser fluence, diameter of metal powder particles, laser pulse width, and the initial temperature of metal particles on solid-liquid-vapor phase change processes of metal particles under nanosecond laser heating are investigated in this paper. A systematic approach of simulating the phase change with uncertain parameters is presented and a sample-based stochastic model is established in order to investigate the influence of different uncertain parameters on the maximum surface temperature of metal particles, the maximum solid-liquid interface location, maximum liquid-vapor interface location, maximum saturation temperature, and maximum recoil pressure and the time needed to reach the maximum solid-liquid interface location. The results show that the mean value and standard deviation of the laser fluence have dominant effects on all output parameters.
Real-time control of electron density in a capacitively coupled plasma
Authors: Keville Bernard , Zhang Yang , Gaman Cezar , Holohan Anthony M. , Daniels Stephen , Turner Miles M.
Published: March 2013

Reactive ion etching (RIE) is sensitive to changes in chamber conditions, such as wall seasoning, which have a deleterious effect on process reproducibility. The application of real time, closed loop control to RIE may reduce this sensitivity and facilitate production with tighter tolerances. The real-time, closed loop control of plasma density with RF power in a capacitively coupled argon plasma using a hairpin resonance probe as a sensor is described. Elementary control analysis shows that an integral controller provides stable and effective set point tracking and disturbance attenuation. The trade off between performance and robustness may be quantified in terms of one parameter, namely the position of the closed loop pole. Experimental results are presented, which are consistent with the theoretical analysis.
Structural Basis for Kinesin-1:Cargo Recognition
Authors: Pernigo Stefano , Lamprecht Anneri , Steiner Roberto A. , Dodding Mark P.
Published: March 2013

Cargo-Motor Interaction

Kinesin-1 directs a diverse array of functions within axons by interacting with many proteins. To understand the mechanisms underpinning kinesin-cargo recognition,

Pernigo
et al.

(p.
356
, published online 21 March) solved the crystal structure of the tetratricopeptide repeat of kinesin light chain 2 bound to a W-acidic cargo peptide from SKIP—a critical host determinant in
Salmonella
pathogenesis that controls lysosome positioning.
Assessing the Relative Effects of Geographic Location and Soil Type on Microbial Communities Associated with Straw Decomposition
Authors: Sun Bo , Wang Xiaoyue , Wang Feng , Jiang Yuji , Zhang Xue-Xian
Published: March 2013

Decomposition of plant residues is largely mediated by soil-dwelling microorganisms whose activities are influenced by both climate conditions and properties of the soil. However, a comprehensive understanding of their relative importance remains elusive, mainly because traditional methods, such as soil incubation and environmental surveys, have a limited ability to differentiate between the combined effects of climate and soil. Here, we performed a large-scale reciprocal soil transplantation experiment, whereby microbial communities associated with straw decomposition were examined in three initially identical soils placed in parallel in three climate regions of China (red soil, Chao soil, and black soil, located in midsubtropical, warm-temperate, and cold-temperate zones). Maize straws buried in mesh bags were sampled at 0.5, 1, and 2 years after the burial and subjected to chemical, physical, and microbiological analyses, e.g., phospholipid fatty acid analysis for microbial abundance, community-level physiological profiling, and 16S rRNA gene denaturing gradient gel electrophoresis, respectively, for functional and phylogenic diversity. Results of aggregated boosted tree analysis show that location rather soil is the primary determining factor for the rate of straw decomposition and structures of the associated microbial communities. Principal component analysis indicates that the straw communities are primarily grouped by location at any of the three time points. In contrast, microbial communities in bulk soil remained closely related to one another for each soil. Together, our data suggest that climate (specifically, geographic location) has stronger effects than soil on straw decomposition; moreover, the successive process of microbial communities in soils is slower than those in straw residues in response to climate changes.
Use of Microfluidic Technology To Analyze Gene Expression during Staphylococcus aureus Biofilm Formation Reveals Distinct Physiological Niches
Authors: Moormeier Derek E. , Endres Jennifer L. , Mann Ethan E. , Sadykov Marat R. , Horswill Alexander R. , Rice Kelly C. , Fey Paul D. , Bayles Kenneth W.
Published: March 2013

The
Staphylococcus aureus cid
and
lrg
operons play significant roles in the control of autolysis and accumulation of extracellular genomic DNA (eDNA) during biofilm development. Although the molecular mechanisms mediating this control are only beginning to be revealed, it is clear that cell death must be limited to a subfraction of the biofilm population. In the present study, we tested the hypothesis that
cid
and
lrg
expression varies during biofilm development as a function of changes in the availability of oxygen. To examine
cid
and
lrg
promoter activity during biofilm development, fluorescent reporter fusion strains were constructed and grown in a BioFlux microfluidic system, generating time-lapse epifluorescence images of biofilm formation, which allows the spatial and temporal localization of gene expression. Consistent with
cid
induction under hypoxic conditions, the
cid
::
gfp
fusion strain expressed green fluorescent protein predominantly within the interior of the tower structures, similar to the pattern of expression observed with a strain carrying a
gfp
fusion to the hypoxia-induced promoter controlling the expression of the lactose dehydrogenase gene. The
lrg
promoter was also expressed within towers but appeared more diffuse throughout the tower structures, indicating that it was oxygen independent. Unexpectedly, the results also demonstrated the existence of tower structures with different expression phenotypes and physical characteristics, suggesting that these towers exhibit different metabolic activities. Overall, the findings presented here support a model in which oxygen is important in the spatial and temporal control of
cid
expression within a biofilm and that tower structures formed during biofilm development exhibit metabolically distinct niches.
Characterization of Pseudomonas aeruginosa Growth on
O
-Acylcarnitines and Identification of a Short-Chain Acylcarnitine Hydrolase
Authors: Meadows Jamie A. , Wargo Matthew J.
Published: March 2013

To survive in various environments, from host tissue to soil, opportunistic bacterial pathogens must be metabolically flexible and able to use a variety of nutrient sources. We are interested in
Pseudomonas aeruginosa
's catabolism of quaternary amine compounds that are prevalent in association with eukaryotes. Carnitine and acylcarnitines are abundant in animal tissues, particularly skeletal muscle, and are used to shuttle fatty acids in and out of the mitochondria, where they undergo β-oxidation. We previously identified the genes required for carnitine catabolism as the first four genes in the carnitine operon (
caiX-cdhCAB
;
PA5388
to
PA5385
). However, the last gene in the operon,
PA5384
, was not required for carnitine catabolism. We were interested in determining the function of PA5384. Bioinformatic analyses along with the genomic location of
PA5384
led us to hypothesize a role for PA5384 in acylcarnitine catabolism. Here, we have characterized PA5384 as an
l
-enantiomer-specific short-chain acylcarnitine hydrolase that is required for growth and hydrolysis of acetyl- and butyrylcarnitine to carnitine and the respective short-chain fatty acid. The liberated carnitine and its downstream catabolic product, glycine betaine, are subsequently available to function as osmoprotectants in hyperosmotic environments and induce transcription of the virulence factor phospholipase C,
plcH
. Furthermore, we confirmed that acylcarnitines with 2- to 16-carbon chain lengths, except for octanoylcarnitine (8 carbons), can be utilized by
P. aeruginosa
as sole carbon and nitrogen sources. These findings expand our knowledge of short-chain acylcarnitine catabolism and also point to remaining questions related to acylcarnitine transport and hydrolysis of medium- and long-chain acylcarnitines.
Draft Genome Sequences of Bordetella holmesii Strains from Blood (F627) and Nasopharynx (H558)
Authors: Tatti Kathleen M. , Loparev Vladimir N. , RanganathanGanakammal Satishkumar , Changayil Shankar , Frace Michael , Weil Michael Ryan , Sammons Scott , MacCannell Duncan , Mayer Leonard W. , Tondella M. Lucia
Published: March 2013

Bordetella holmesii
, a human pathogen, can confound the diagnosis of respiratory illness caused by
Bordetella pertussis
. We present the draft genome sequences of two
B. holmesii
isolates, one from blood, F627, and one from the nasopharynx, H558. Interestingly, important virulence genes that are present in
B. pertussis
are not found in
B. holmesii
.
Genome Sequence of Cronobacter sakazakiiSP291, a Persistent Thermotolerant Isolate Derived from a Factory Producing Powdered Infant Formula
Authors: Power Karen A. , Yan Qiongqiong , Fox Edward M. , Cooney Shane , Fanning Séamus
Published: March 2013

Cronobacter
is an opportunistic pathogen associated with meningitis in neonates. Based on long-term surveillance of a powdered infant formula production facility, a persistent and thermotolerant isolate, denoted
Cronobacter sakazakii
SP291, was detected. Here we report the complete genome along with the sequences of three plasmids identified in this organism.
Genome Sequence of a Plant-Associated Bacterium, Bacillus amyloliquefaciens Strain UCMB5036
Authors: Manzoor Shahid , Niazi Adnan , Bejai Sarosh , Meijer Johan , Bongcam-Rudloff Erik
Published: March 2013

We announce here the genome sequence of
Bacillus amyloliquefaciens
strain UCMB5036, a plant growth-promoting bacterium isolated from a cotton plant. Its genome contains gene clusters involved in nonribosomal synthesis of secondary metabolites known for their antimicrobial activities. The availability of this genome will provide novel insights into plant-bacterium–associated activities.
Draft Genome Sequence of
Microbacterium
sp. Strain UCD-TDU (Phylum
Actinobacteria
)
Authors: Bendiks Zachary A. , Lang Jenna M. , Darling Aaron E. , Eisen Jonathan A. , Coil David A.
Published: March 2013

Here, we present the draft genome sequence of
Microbacterium
sp. strain UCD-TDU, a member of the phylum
Actinobacteria
. The assembly contains 3,746,321 bp (in 8 scaffolds). This strain was isolated from a residential toilet as part of an undergraduate student research project to sequence reference genomes of microbes from the built environment.
Effects of Electro-Acupuncture on Oestrogen Levels, Body Weight, Articular Cartilage Histology and Mmp-13 Expression in Ovariectomised Rabbits
Authors: Qin Yuxi , He Jing , Xia Lu , Guo Hua , He Chengqi
Published: March 2013

Background

Electro-acupuncture (EA) treatment has been shown to decrease pain and improve the function of ovariectomised (OVX) rats with osteoarthritis (OA); however, the underlying mechanisms remain unclear.

Object

We used OVX rabbits to replicate natural human menopausal processes and to evaluate whether EA could be used to prevent and treat postmenopausal OA.

Methods

The rabbits were randomly divided into four groups of eight: a normal control group (NC), an OVX group, an ERT group (oestrogen replacement therapy after OVX) and an EA group (EA therapy after OVX). After the interventions, all of the animals were killed. Serum oestrogen levels and body weight were measured. The transcription of matrix metalloproteinase-13 (MMP-13) mRNA was detected using reverse transcriptase-PCR. Modified Mankin scores were used for histological assessment. Expression of MMP-13 in cartilage was determined by immunohistochemistry.

Results

Both the EA group and the ERT group had increased serum oestrogen levels (p=0.028, p=0.037 respectively), as well as decreased expression of MMP-13 (p=0.000, p=0.000, respectively), relative to the OVX group. The body weight of the EA group was lower than that of the OVX group and the NC group (p=0.007), as well as the ERT group (p=0.010).

Conclusions

EA could be a new method for preventing and treating postmenopausal OA by producing endogenous sex hormones that inhibit the expression of MMP-13 and cause weight loss with no side effects and a relatively low cost.
Is the work ability index useful to evaluate absence days in ankylosing spondylitis patients? A cross-sectional study
Authors: Meyer Katharina , Niedermann Karin , Tschopp Alois , Klipstein Andreas
Published: March 2013

Background

The work incapacity of ankylosing spondylitis (AS) ranges between 3% and 50% in Europe. In many countries, work incapacity is difficult to quantify. The work ability index (WAI) is applied to measure the work ability in workers, but it is not well investigated in patients.

Aims

To investigate the work incapacity in terms of absence days in patients with AS and to evaluate whether the WAI reflects the absence from work.

Hypothesis

Absence days can be estimated based on the WAI and other variables.

Design

Cross-sectional design.

Setting

In a secondary care centre in Switzerland, the WAI and a questionnaire about work absence were administered in AS patients prior to cardiovascular training. The number of absence days was collected retrospectively. The absence days were estimated using a two-part regression model.

Participants

92 AS patients (58 men (63%)). Inclusion criteria: AS diagnosis, ability to cycle, age between 18 and 65 years. Exclusion criteria: severe heart disease.

Primary and secondary outcome measures

Absence days.

Results

Of the 92 patients, 14 received a disability pension and 78 were in the working process. The median absence days per year of the 78 patients due to AS alone and including other reasons was 0 days (IQR 0–12.3) and 2.5 days (IQR 0–19), respectively. The WAI score (regression coefficient=−4.66 (p<0.001, CI −6.1 to −3.2), ‘getting a disability pension’ (regression coefficient=−106.8 (p<0.001, 95% CI −141.6 to −72.0) and other not significant variables explained 70% of the variance in absence days (p<0.001), and therefore may estimate the number of absence days.

Conclusions

Absences in our sample of AS patients were equal to pan-European countries. In groups of AS patients, the WAI and other variables are valid to estimate absence days with the help of a two-part regression model.
OPTIMAL PRICING AND REPLENISHMENT POLICY FOR NONINSTANTANEOUS DETERIORATING ITEMS AND TWO LEVELS OF STORAGE
Authors: KROMMYDA IRIS-PANDORA , SKOURI KONSTANTINA , KONSTANTARAS IOANNIS , GANAS IOANNIS
Published: March 2013

In this paper an inventory control system for deteriorating items with price and time-dependent demand is studied. The majority of the existing literature in inventory systems for deteriorating items, deals with items that are subject to deterioration as soon as they enter the warehouse. However, there are items that have a shelf-life and start deteriorating after a time lag (noninstantaneous deteriorating items). Under some special circumstances, i.e., attractive price discount, low storage cost, high demand, etc; the procurement of a large amount of such items at a time is decided. Because of the fixed capacity of the own warehouse (OW), a rented warehouse (RW) is used to store the excess quantity. In the present paper, a two-warehouse inventory model for noninstantaneous deteriorating items is developed. Shortages at OW are also allowed and partially backlogged at a rate, which is any nonincreasing function of the waiting time up to the next replenishment. For this model, we propose a simple solution procedure to determine the optimal pricing and replenishment schedule.
SOLENOIDAL LIPSCHITZ TRUNCATION FOR PARABOLIC PDEs
Authors: BREIT D. , DIENING L. , SCHWARZACHER S.
Published: March 2013

We consider functions u ∈ L∞(L2)∩Lp(W1, p) with 1 < p < ∞ on a time–space domain. Solutions to nonlinear evolutionary PDEs typically belong to these spaces. Many applications require a Lipschitz approximation uλ of u which coincides with u on a large set. For problems arising in fluid mechanics one needs to work with solenoidal (divergence-free) functions. Thus, we construct a Lipschitz approximation, which is also solenoidal. As an application we revise the existence proof for non-stationary generalized Newtonian fluids of Diening, Ruzicka and Wolf, Existence of weak solutions for unsteady motions of generalized Newtonian fluids, Ann. Sc. Norm. Super. Pisa Cl. Sci. (5) 9 (2010) 1–46. Since div uλ = 0, we are able to work in the pressure free formulation, which heavily simplifies the proof. We also provide a simplified approach to the stationary solenoidal Lipschitz truncation of Breit, Diening and Fuchs, Solenoidal Lipschitz truncation and applications in fluid mechanics, J. Differential Equations253 (2012) 1910–1942.
Late Palaeozoic–Early Cenozoic tectonic development of Southern Turkey and the easternmost Mediterranean region: evidence from the inter-relations of continental and oceanic units
Authors: Robertson Alastair H. F. , Parlak Osman , Ustaömer Timur
Published: March 2013

Reconstructions of the Anatolian continent and adjacent areas assume the existence of one or more continental fragments during Mesozoic–Early Cenozoic time. These rifted from North Africa (Gondwana) during the Triassic, drifted across the Mesozoic Tethys and collided with Eurasia during latest Cretaceous–Paleocene time. Current reconstructions range from a regional-scale Tauride–Anatolide continent with oceanic basins to the north and south, to numerous rifted continental fragments separated by small oceanic basins. Field-based evidence for the inter-relations of the continental blocks and associated carbonate platforms is discussed and evaluated here, especially to distinguish between sutured oceans and intra-continental convergence zones. Several crustal units are restored as different parts of one large Tauride–Anatolide continent, whereas several smaller crustal units (e.g. Kırşehir massif; Bitlis/Pütürge and Alanya/Kyrenia units) are interpreted as continental fragments bordered by oceanic crust. We infer a relatively wide İzmir–Ankara–Erzincan ocean in the north and also a wide South Neotethyan ocean in the south. Several smaller oceanic strands (e.g. Inner Tauride ocean, Berit ocean and Alanya ocean) were separated by continental fragments. Our proposed reconstructions are shown on palaeotectonic maps for Late Permian to Mid-Miocene. The reconstructions have interesting implications for crustal processes, including ophiolite genesis and emplacement.
The Immune Response in Tuberculosis
Authors: O'Garra Anne , Redford Paul S. , McNab Finlay W. , Bloom Chloe I. , Wilkinson Robert J. , Berry Matthew P.R.
Published: March 2013

There are 9 million cases of active tuberculosis reported annually; however, an estimated one-third of the world's population is infected with Mycobacterium tuberculosis and remains asymptomatic. Of these latent individuals, only 5–10% will develop active tuberculosis disease in their lifetime. CD4+T cells, as well as the cytokines IL-12, IFN-γ, and TNF, are critical in the control of Mycobacterium tuberculosis infection, but the host factors that determine why some individuals are protected from infection while others go on to develop disease are unclear. Genetic factors of the host and of the pathogen itself may be associated with an increased risk of patients developing active tuberculosis. This review aims to summarize what we know about the immune response in tuberculosis, in human disease, and in a range of experimental models, all of which are essential to advancing our mechanistic knowledge base of the host-pathogen interactions that influence disease outcome.
Hydrogen sulfide modulates sinusoidal constriction and contributes to hepatic micorcirculatory dysfunction during endotoxemia
Authors: Norris Eric J. , Feilen Nicole , Nguyen Nhat H. , Culberson Cathy R. , Shin Min C. , Fish Madeleine , Clemens Mark G.
Published: March 2013

Hydrogen sulfide (H2S) affects vascular resistance; however, its effect on the hepatic microcirculation has not been investigated. Hepatic sinusoidal perfusion is dysregulated during sepsis, contributing to liver injury. Therefore, the present study determined the effect of H2S on the hepatic microcirculation and the contribution of endogenous H2S to hepatic microcirculatory dysfunction in an endotoxin model of sepsis. Portal infusion of H2S increased portal pressure in vivo (6.8 ± 0.2 mmHg before H2S vs. 8.6 ± 0.8 mmHg peak during H2S infusion, P < 0.05). Using intravital microscopy, we observed decreased sinusoidal diameter (6.2 ± 0.27 μm before H2S vs. 5.7 ± 0.3 μm after H2S, P < 0.05) and increased sinusoidal heterogeneity during H2S infusion ( P < 0.05) and net constriction. Since hepatic H2S levels are elevated during sepsis, we used the cystathionine γ lyase inhibitor dl-propargylglycine (PAG) to determine the contribution of H2S to the hypersensitization of the sinusoid to the vasoconstrictor effect of endothelin-1 (ET-1). PAG treatment significantly attenuated the sinusoidal sensitization to ET-1 in endotoxin-treated animals. ET-1 infusion increased portal pressure to 175% of baseline in endotoxemic animals, which was reduced to 143% following PAG treatment ( P < 0.05). PAG abrogated the increase in sinusoidal constriction after ET-1 infusion in LPS-treated rats (30.9% reduction in LPS rats vs. 11.6% in PAG/LPS rats, P < 0.05). Moreover, PAG treatment significantly attenuated the increase in NADH fluorescence following ET-1 exposure during endotoxemia (61 grayscale units LPS vs. 21 units in PAG/LPS, P < 0.05), suggesting an improvement in hepatic oxygen availability. This study is the first to demonstrate a vasoconstrictor action of H2S on the hepatic sinusoid and provides a possible mechanism for the protective effect of PAG treatment during sepsis.
Skeletal muscle fat metabolism after exercise in humans: influence of fat availability
Authors: Kimber Nicholas E. , Cameron-Smith David , McGee Sean L. , Hargreaves Mark
Published: March 2013

The mechanisms facilitating increased skeletal muscle fat oxidation following prolonged, strenuous exercise remain poorly defined. The aim of this study was to examine the influence of plasma free fatty acid (FFA) availability on intramuscular malonyl-CoA concentration and the regulation of whole-body fat metabolism during a 6-h postexercise recovery period. Eight endurance-trained men performed three trials, consisting of 1.5 h high-intensity and exhaustive exercise, followed by infusion of saline, saline + nicotinic acid (NA; low FFA), or Intralipid and heparin [high FFA (HFA)]. Muscle biopsies were obtained at the end of exercise (0 h) and at 3 and 6 h in recovery. Ingestion of NA suppressed the postexercise plasma FFA concentration throughout recovery ( P < 0.01), except at 4 h. The alteration of the availability of plasma FFA during recovery induced a significant increase in whole-body fat oxidation during the 6-h period for HFA (52.2 ± 4.8 g) relative to NA (38.4 ± 3.1 g; P < 0.05); however, this response was unrelated to changes in skeletal muscle malonyl-CoA and acetyl-CoA carboxylase (ACC)β phosphorylation, suggesting mechanisms other than phosphorylation-mediated changes in ACC activity may have a role in regulating fat metabolism in human skeletal muscle during postexercise recovery. Despite marked changes in plasma FFA availability, no significant changes in intramuscular triglyceride concentrations were detected. These data suggest that the regulation of postexercise skeletal muscle fat oxidation in humans involves factors other than the 5′AMP-activated protein kinase-ACCβ-malonyl-CoA signaling pathway, although malonyl-CoA-mediated regulation cannot be excluded completely in the acute recovery period.
Synchronization between Fractional-Order and Integer-Order Hyperchaotic Systems via Sliding Mode Controller
Authors: Wu Yan-Ping , Wang Guo-Dong
Published: March 2013

The synchronization between fractional-order hyperchaotic systems and integer-order hyperchaotic systems via sliding mode controller is investigated. By designing an active sliding mode controller and choosing proper control parameters, the drive and response systems are synchronized. Synchronization between the fractional-order Chen chaotic system and the integer-order Chen chaotic system and between integer-order hyperchaotic Chen system and fractional-order hyperchaotic Rössler system is used to illustrate the effectiveness of the proposed synchronization approach. Numerical simulations coincide with the theoretical analysis.
Information Fields Navigation with Piece-Wise Polynomial Approximation for High-Performance OFDM in WSNs
Authors: Wei Wei , Shen Peiyi , Zhang Ying , Zhang Liang
Published: March 2013

Since Wireless sensor networks (WSNs) are dramatically being arranged in mission-critical applications,it changes into necessary that we consider application requirements in Internet of Things. We try to use WSNs to assist information query and navigation within a practical parking spaces environment. Integrated with high-performance OFDM by piece-wise polynomial approximation, we present a new method that is based on a diffusion equation and a position equation to accomplish the navigation process conveniently and efficiently. From the point of view of theoretical analysis, our jobs hold the lower constraint condition and several inappropriate navigation can be amended. Information diffusion and potential field are introduced to reach the goal of accurate navigation and gradient descent method is applied in the algorithm. Formula derivations and simulations manifest that the method facilitates the solution of typical sensor network configuration information navigation. Concurrently, we also treat channel estimation and ICI mitigation for very high mobility OFDM systems, and the communication is between a BS and mobile target at a terrible scenario. The scheme proposed here combines the piece-wise polynomial expansion to approximate timevariations of multipath channels. Two near symbols are applied to estimate the first-and second-order parameters. So as to improve the estimation accuracy and mitigate the ICI caused by pilot-aided estimation, the multipath channel parameters were reestimated in timedomain employing the decided OFDM symbol. Simulation results show that this method would improve system performance in a complex environment.