bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Simulation of Radiant Floor Heating System Using Hele-Shaw Analogy
Authors: Ngo C. C. , Peinder C. G.
Published: August 2016

Radiant floor heating systems are becoming increasingly popular in green building designs. Typically, solar or geothermal energy is employed as a source for such hydronic heating systems. Buried heating pipe system can be used for heating both residential and industrial spaces as well as defrosting snow on walkways, driveways and sport fields. Most of the heating pipes considered in such applications are buried in a porous medium (i.e., insulation layer or soils). Hele-Shaw cells with different pipe spacing were constructed to simulate different floor heating configurations. The objective of the present experimental study is to examine the flow field within porous medium using the Hele-Shaw analogy. The flow visualization experiment was set up to investigate how a change in pipe spacing and pipe temperature would affect the flow patterns from the heated pipes. Using time-elapsed photographs, one observes that the flow fields for different pipe spacings with different buoyancy strengths display distinct characteristics.
Foam Insulation Behavior in Void Space Under Fire Conditions
Authors: Kurzawski Andrew , Ezekoye Ofodike A.
Published: August 2016

A fire contained within a room can spread into void spaces in the walls and ceiling through penetrations in the material that lines the compartment. Few studies have looked at how a room and contents fire transitions to a structural fire. One of the active areas of fire research is the coupling of the fire to the structure. Lightweight wood frame construction represents the majority of residential construction in the U.S. The construction details and choice of materials will affect the overall fire resistance of the structure. Because of the relative lack of knowledge on the fire penetration into wall spaces, this research examined how fire might penetrate into the void spaces of wood framed structures.

In the U.S.A., a critical barrier to the penetration of hot gas products into void spaces is provided by the gypsum-board skin of the compartment. For most compartments, there are many penetrations within the compartment’s gypsum-board skin. Common potential access points include security system wiring (e.q. smoke detectors and cameras), ventilation fixtures, light switches, and electrical outlets among others. A hole in the gypsum may create opportunities for void space ignition. One of the purposes of this work is to develop a small scale testing system to characterize fire driven flow and heat transfer into a void space. With such an apparatus, one can rapidly identify materials that are prone to igniting for a given leakage geometry and fire size. Common materials found in void spaces include wooden structural members, plywood/oriented strand board, a variety of insulation types, and vapor barriers. This study discusses the characteristics of the small scale experimental system and preliminary tests on a range of void space construction materials.
Mode-Decay Molecular Dynamics for Frequency-Dependent Phonon Scattering Rates
Authors: Gerboth M. D. , Walker D. G.
Published: August 2016

The thermal conductivity of crystalline materials can be determined in a statistical mechanical framework as long as phonon relaxation rates are known. Unfortunately, these quantities are difficult if not impossible to measure directly, and attempts to deduce these quantities yield gross averages not energy dependent relationships. Consequently, researchers often rely on heuristic models such as Holland’s suite of scattering rates for various phonon modes. A new molecular dynamics method was developed to estimate mode-dependent scattering rates by tracking the decay of an initially imposed standing wave. The wave vector is systematically changed and the corresponding decay is collected. Ultimately, the the thermal conductivity can be reconstructed using a Landauer formalism. The phonon scattering rates of a LJ crystal are calculated using this method. The standing wave decay approach allows scattering rates to be probed more directly than wave packet simulations, which are often used to obtain transmission coefficients.
Numerical Analysis on Cooling Performance for FET Heat Sink
Authors: Jang Kyung Min , Kim Jun Young , Eum Cholongi , Kim KwangSun
Published: August 2016

With the improved performance of IT devices like car microprocessors, the heat generated in the electric devices are being increased in amount. The increased heating value degrades the performance of devices and circuits, which will affect the durability and reliability of products eventually by causing their failure. Therefore, a study on the cooling performance improvement of heat sinks is essential to decrease the temperatures of the field effect transistors (FETs) in cars. In this study, numerical analysis and experimental tests were carried out to develop a new heat sink design for a different FET material, heat conductive resin. Without the heat sink, the new FET had a temperature distribution of 70–90 Celsius, which was measured in the laboratory environment similar to the real chamber within a car. Based on the numerical and experimental test and analysis of the FET new heat sink system, the improved shape and array of the fins are developed that meet the target temperature of the FET. For heat sinks, efficient cooling design and reduced manufacturing costs are derived from the comparison with those of old heat sink material, Aluminum.
Dual Fuel Concept for an Innovative Co-Axial Burner, Thermal Characteristics and Combustion Performance
Authors: Soliman Joseph , Emara Ahmed , Hussien Adel
Published: August 2016

The demand for industrial burners and gas turbine engines with reduced emission levels, stable combustion conditions and low specific fuel consumption is the goal at the past two decades. A significant challenge is to develop a practical dual fuel corresponded with these requirements in the way to produce an efficient combustion and to comply with environmental concerns and government regulations.

The investigated burner consists of eight gaseous jets arranged in two consecutively interacted equal lotus bundles in the axial direction downstream of the flow. These eight jets can be easily moved and directed to penetrate the combustion reaction zone at different axial positions with four inclination angles at the burner axis (θ= 0°, 30°, 45°, and 60°). This axial motion is easily performed by adjusting few screws mounted on the burner end in the way to facilitate the jet interaction inside the surrounded combustion air.

The present work aims to demonstrate the flame structure, inflame temperature, and stack emissions at different liquid fuel ratio, gaseous fuel injection locations and jet inclination angles. It is noticed that, the two different fuels at different interaction locations have an influence on the pollutant emissions and temperature as well as the combustion efficiency. In addition, increasing the gaseous fuel reduces the flame size and increases the flame temperature.
Numerical Modeling of the Moisture Transfer Through Wooden Desk and Hygro-Mechanical Coupling by Linking ANSYS and MATLAB Software
Authors: Simeunovic Goran , Vyhlidal Tomas
Published: August 2016

Presented research is a continuation of the our previous work [1], where numerical modelling tools are applied to study relation between the moisture distribution and related stress and strain in painted wooden desks. In this paper, the very simply linear model for modelling of the stress in the wood is substituted by more complex model. Used stress model is based on St. Venant – Kirchhoff-material and stress/strain relation in the form of Hooke’s law for small strains presented in [2]. Furthermore, the previous 3D CFD model of the Chapel of the Holy Cross at Karlstejn Castle is completed by added the influence of the visitors on the indoor climate. Same as in the previous above cited work, the temperature and relative humidity distribution in the chapel is obtained by FLUENT 3D CFD model of the chapel and these results are post-processed and used as boundary condition for the calculation part, which is performed in the MATLAB. This problem is being investigated as one of the tasks of the European project Climate for Culture (http://www.climateforculture.eu/).
Heat Transfer Enhancement of Reactor Utilizing Taylor-Poiseuille Flow
Authors: Ye Li , Peng Huajun , Zhou Bo , Yang Mo , Li Zheng , Zhang Yuwen
Published: August 2016

Numerical studies have been conducted to determine the heat transfer performances in a Taylor-Poiseuille flow regime. The flow is confined between two different heated, concentric cylinders. The inner cylinder is allowed to rotate while the outer one remains fixed, an axial flow is added. The influences of rotation Taylor number and axial Reynolds number on heat transfer coefficients are investigated. Results show that temperature in the flow regime presents a remarkable sinusoidal periodicity as the result of the axial arrangement of Taylor vortices, so does the local heat transfer coefficients. Heat transfer efficiency gets strengthened with increasing Taylor number, while damped with increasing Reynolds number. The accuracy of the simulation is validated by compared to the existing linear stability analysis.
Metal-Hydride Adsorption Systems for Space Conditioning in Commercial and Residential Buildings
Authors: Zhong Yongfang , Glanville Paul
Published: August 2016

A review on thermally-driven metal-hydride adsorption systems is conducted to identify its current development for cooling and heating applications. The state-of-the-art status of these systems is summarized, and the advantages and disadvantages are discussed as comparing to other sorption systems. Moreover, the potential of a heat pump system with metal hydride and hydrogen is evaluated for building space conditioning application. Two methods are used for the evaluation: one is the performance evaluation with system modeling for the operating conditions specified by ASHRAE Standard 116; and the other is a thermo-economic analysis as comparing to electric space conditioning systems. The results of the evaluation are presented in addition to metal hydride selection and the property characterization of selected working media from in-house tests. The conclusion from the thermo-economic analysis is applicable to all thermally-driven systems for space conditioning in commercial and residential buildings.
Enhanced Convective Heat Transfer in High Porosity Metal Foams
Authors: Jin L. W. , Ma C. F. , Zhao M. , Meng X. Z. , Kang W. B. , Lu Z. , Wei L. C.
Published: August 2016

Due to the characteristics of large surface area-to-volume ratio and inter-connected ligament structure, open-cell metal foams are promising materials for enhancing heat transfer in forced convection and have been researched for thermal applications in thermal management systems, air-cooled condensers and compact heat sinks for power electronics. However, the tortuous complex flow path inside metal foams leads to relatively higher pressure drop, which requires larger system pumping power. Hence, it is important to study the heat transfer performance of metal foam compared to its flow resistance characteristics.

Detailed experimental study of forced convection subjected to constant heat flux in metal foams is conducted in the present paper. The objective of the investigation is to compare the heat transfer performance and hydraulic characteristics of aluminum foams with different pore densities. The tested aluminium foam samples are of 50.0mm (L) × 25.0mm (W) × 12.0mm (H) in geometric dimensions and pore densities are of 5ppi, 10ppi and 40ppi, respectively. Experiments are performed in forced convective heat transfer using deionized water as the cooling fluid. To minimize the heat loss, the test section is built adiabatically with Teflon and polycarbonate materials. The inlet flow velocity, the temperature distribution on the heating surface and the pressure drop across the metal form are measured. Based on the analysis of experimental data, it is found that convective heat transfer performance in high ppi foam is higher than that in low ppi foam, while the pressure drop shows the opposite trend for a given flow rate.
The Effect of Noncondensables on the Buoyancy-Thermocapillary Convection in Confined and Volatile Fluids
Authors: Qin Tongran , Yoda Minami , Grigoriev Roman O.
Published: August 2016

Convection in confined layers of volatile liquids has been studied extensively under atmospheric conditions. Recent experimental results [1] have shown that removing most of the air from a sealed cavity significantly alters the flow structure and, in particular, suppresses transitions between the different convection patterns found at atmospheric conditions. Yet, at the same time, this has almost no effect on the flow speeds in the liquid layer. To understand these results, we have formulated and numerically implemented a detailed transport model that accounts for mass and heat transport in both phases as well as the phase change at the interface. Surprisingly, the numerical simulations show that noncondensables have a large effect on buoyancy-thermocapillary flow at concentrations even as low as 1%, i.e., much lower than those achieved in experiment.
Prediction of Viscosity of Nanofluids Using Artificial Neural Networks
Authors: Zhao Ningbo , Li Shuying , Wang Zhitao , Cao Yunpeng
Published: August 2016

The viscosity of nanofluids can be affected by many factors. In pursuit of such improved accuracy, model-based viscosity prediction methods have become more complicated. Therefore, there is a need to find an alternative approach that is able to provide a quick solution to viscosity prediction for nanofluids. In this paper, a novel viscosity prediction approach using artificial neural networks (ANN) is introduced as an alternative to the model-based viscosity prediction approach to provide a quick and accurate estimation of nanofluids viscosity. Radial basis function (RBF) neural networks has been utilized to form viscosity prediction architectures. Alumina (Al2O3)-water nanofluids from existing literatures were used to test the effectiveness of the proposed method. The results showed that RBF neural network model had a reasonable agreement in predicting experimental data. The findings of this paper indicated that the ANN model was an effective method for prediction of the viscosity of nanofluids and had better prediction accuracy and simplicity compared with the other existing theoretical methods.
Fabrication of high aspect ratio AFM probes with different materials inspired by TEM “lift-out” method
Authors: Tan Swee Ching , Zhao Hangbo , Thompson Carl V.
Published: August 2016

The most commonly used materials in all commercially available high-aspect-ratio (HAR) nanowire's (NW) tips are made of silicon and carbon nanotube which limit their applications in other types of atomic force microscopy (AFM), such as conducting AFM and magnetic force microscope. Therefore, a simple process inspired by cross-sectional transmission electron microscopy sample preparation method was used to demonstrate the feasibility of fabricating HAR AFM probes, which can easily define the tilt angle of the NW tip with respect to the direction that is normal to the axis of the cantilever to which it is attached by simply tilting the sample stage where the cantilever is placed. This is very important as it enables precise control of the inclination angle of the NW tip and allows the tip to be made perpendicular to the probed surface for scanning with different AFM mounts. Two different tips were fabricated, one attached parallel and the other attached at an angle of 13° with respect to the normal of the cantilever axis. These tips were used to profile the topography of a silicon nanopillar array. Only the probe attached at an angle of 13° allowed mapping of the topography between nanopillars. This is the first successful demonstration of an HAR AFM tip being used to map the topography of a nanopillar array. In addition, the authors also demonstrated that this method can be extended to fabricate HAR AFM tips of different materials such as copper with a slightly modified approach.
Plasma enhanced atomic layer deposition of ZnO with diethyl zinc and oxygen plasma: Effect of precursor decomposition
Authors: Muneshwar Triratna , Shoute Gem , Barlage Doug , Cadien Ken
Published: August 2016

Although atomic layer deposition (ALD) of ZnO using diethyl zinc (DEZ) precursor has been extensively reported, variation in growth-per-cycle (GPC) values and the range of substrate temperature (Tsub) for ALD growth between related studies remain unexplained. For identical processes, GPC for the characteristic self-limiting ALD growth is expected to be comparable. Hence, a significant variation in GPC among published ZnO ALD studies strongly suggests a concealed non-ALD growth component. To investigate this, the authors report plasma-enhanced ALD growth of ZnO using DEZ precursor and O2 inductively coupled plasma. The effect of Tsub on ZnO GPC was studied with deposition cycles (1) 0.02 s–15 s–6 s–15 s, (2) 0.10 s–15 s–15 s–15 s, and (3) 0.20 s–15 s–30 s–15 s, where the cycle parameters t1–t2–t3–t4 denote duration of DEZ pulse, post-DEZ purge, plasma exposure, and postplasma purge, respectively. The non-ALD growth characteristics observed at Tsub ≥ 60 °C are discussed and attributed to DEZ precursor decomposition. The authors demonstrate ZnO growth at Tsub = 50 °C to be self-limiting with respect to both t1 and t3 giving GPC of 0.101 ± 0.001 nm/cycle. The effect of precursor decomposition related (non-ALD) growth at Tsub ≥ 60 °C is illustrated from comparison of optical dielectric function, electrical resistivity, and surface roughness of ZnO films deposited at Tsub = 50, 125, and 200 °C.
Molecular simulations of C60 self-assembly on metal-adsorbed Si(111) surfaces
Authors: Utas Oleg A. , Olyanich Dmitry A. , Mararov Vsevolod V. , Utas Tatiana V. , Zotov Andrey V. , Saranin Alexander A.
Published: August 2016

The authors have proposed a simulation procedure for the evaluation of energetics of C60 islands on crystalline surfaces that allows questions relating to shape, size, and orientation of the islands to be addressed. Simulation consists of placing a patch of close-packed C60 array of a given shape and size on a surface potential relief and finding energy minima by variation of island position and orientation. Upon appropriate adjustment of the surface potential relief, simulations reproduce well all the main results of the scanning tunneling microscopy observations. For C60 islands forming on In-adsorbed Si(111)3×3-Au and pristine Si(111)3×3-Ag surfaces, the optimal surface relief shows up as a periodic array of cosine-shaped peaks. The proposed approach provides a hint for understanding the driving mechanisms of C60 self-assembly, and, in principle, it can be applied to other adsorbate-substrate systems.
Proteome-wide analysis of arginine monomethylation reveals widespread occurrence in human cells
Authors: Larsen Sara C. , Sylvestersen Kathrine B. , Mund Andreas , Lyon David , Mullari Meeli , Madsen Maria V. , Daniel Jeremy A. , Jensen Lars J. , Nielsen Michael L.
Published: August 2016

Arginine methylation is prevalent throughout the proteome and regulates the localization and function of splicing and RNA transport factors.
WNK1 inhibits T cell adhesion
Authors: Foley John F.
Published: August 2016

The kinase WNK1 inhibits the integrin-mediated adhesion of T cells and promotes their migration.
Genome and Plasmid Analysis of
bla
IMP-4
-Carrying Citrobacter freundii B38
Authors: Xiong Jianhui , Déraspe Maxime , Iqbal Naeem , Ma Jennifer , Jamieson Frances B. , Wasserscheid Jessica , Dewar Ken , Hawkey Peter M. , Roy Paul H.
Published: August 2016

Sequencing of the
bla
IMP-4
-carrying
C. freundii
B38 using the PacBio SMRT technique revealed that the genome contained a chromosome of 5,134,500 bp and three plasmids, pOZ172 (127,005 bp), pOZ181 (277,592 bp), and pOZ182 (18,467 bp). Plasmid pOZ172 was identified as IncFIIY, like pP10164-NDM and pNDM-EcGN174. It carries a class 1 integron with four cassettes (
bla
IMP-4
-
qacG2
-
aacA4
-
aphA15
) and a complete hybrid
tni
module (
tniR
-
tniQ
-
tniB
-
tniA
). The recombination of
tniR
from Tn
402
(identical) with
tniQBA
from Tn
5053
(99%) occurred within the
res
site of Tn
402
/
5053
. The Tn
402/5053
-like integron, named Tn
6017
, was inserted into Tn
1722
at the
res
II site. The replication, partitioning, and transfer systems of pOZ181 were similar to those of IncHI2 plasmids (e.g., R478) and contained a
sul1
-type class 1 integron with the cassette array
orf-dfrA1-orf-gcu37-aadA5
linked to an upstream Tn
1696 tnpA-tnpR
and to a downstream 3′ conserved sequence (3′-CS) and IS
CR1
. A Tn
2
transposon encoding a
bla
TEM-1
β-lactamase was identified on pOZ182. Other interesting resistance determinants encoded on the B38 chromosome included multidrug resistance (MDR) efflux pumps, an AmpC β-lactamase, and resistances to Cu, Ag, As, and Zn. This is the first report of a complete
tni
module linked to a
bla
IMP-4
-carrying class 1 integron, which, together with other recently reported non-
sul1
integrons, represents the emergence of a distinct evolutionary lineage of class 1 integrons lacking a 3′-CS (
qacEΔ1
-
sul1
). The unique cassette array, complete
tni
module of Tn
6017
, and incompatibility group of pOZ172 suggest a
bla
IMP-4
evolutionary pathway in
C. freundii
B38 different from that for other
bla
IMP-4
genes found in Gram-negative bacteria in the Western Pacific region.
Population Pharmacokinetics and Dosing Regimen Optimization of Meropenem in Cerebrospinal Fluid and Plasma in Patients with Meningitis after Neurosurgery
Authors: Lu Cheng , Zhang Yuyi , Chen Mingyu , Zhong Ping , Chen Yuancheng , Yu Jicheng , Wu Xiaojie , Wu Jufang , Zhang Jing
Published: August 2016

Meropenem is used to manage postneurosurgical meningitis, but its population pharmacokinetics (PPK) in plasma and cerebrospinal fluid (CSF) in this patient group are not well-known. Our aims were to (i) characterize meropenem PPK in plasma and CSF and (ii) recommend favorable dosing regimens in postneurosurgical meningitis patients. Eighty-two patients were enrolled to receive meropenem infusions of 2 g every 8 h (q8h), 1 g q8h, or 1 g q6h for at least 3 days. Serial blood and CSF samples were collected, and concentrations were determined and analyzed via population modeling. Probabilities of target attainment (PTA) were predicted via Monte Carlo simulations, using the target of unbound meropenem concentrations above the MICs for at least 40% of dosing intervals in plasma and at least of 50% or 100% of dosing intervals in CSF. A two-compartment model plus another CSF compartment best described the data. The central, intercentral/peripheral, and intercentral/CSF compartment clearances were 22.2 liters/h, 1.79 liters/h, and 0.01 liter/h, respectively. Distribution volumes of the central and peripheral compartments were 17.9 liters and 3.84 liters, respectively. The CSF compartment volume was fixed at 0.13 liter, with its clearance calculated by the observed drainage amount. The multiplier for the transfer from the central to the CSF compartment was 0.172. Simulation results show that the PTAs increase as infusion is prolonged and as the daily CSF drainage volume decreases. A 4-hour infusion of 2 g q8h with CSF drainage of less than 150 ml/day, which provides a PTA of >90% for MICs of ≤8 mg/liter in blood and of ≤0.5 mg/liter or 0.25 mg/liter in CSF, is recommended. (This study has been registered at ClinicalTrials.gov under identifier NCT02506686.)
Emtricitabine-Triphosphate in Dried Blood Spots as a Marker of Recent Dosing
Authors: Castillo-Mancilla Jose , Seifert Sharon , Campbell Kayla , Coleman Stacey , McAllister Kevin , Zheng Jia-Hua , Gardner Edward M. , Liu Albert , Glidden David V. , Grant Robert , Hosek Sybil , Wilson Craig M. , Bushman Lane R. , MaWhinney Samantha , Anderson Peter L.
Published: August 2016

New objective measures of antiretroviral adherence are needed. We determined if emtricitabine triphosphate (FTC-TP) in dried blood spots (DBS) can be used as a marker of recent dosing with tenofovir disoproxil fumarate-emtricitabine (TDF-FTC). The half-life of FTC-TP was estimated in DBS samples obtained from an intensive pharmacokinetic (PK) study of coformulated TDF-FTC in HIV-negative and HIV-infected participants. The concordance of quantifiable FTC-TP in DBS with tenofovir (TFV)/FTC in plasma was evaluated by utilizing paired plasma-DBS samples from participants enrolled in 2 large preexposure prophylaxis (PrEP) open-label trials. The time to FTC-TP nondetectability after TDF-FTC dosing was evaluated utilizing DBS from HIV-negative participants enrolled in a directly observed therapy study of variable adherence to TDF-FTC. The mean (95% confidence interval [CI]) terminal half-life of FTC-TP in the PK study was 35 (23 to 47) h. A total of 143/163 (88%) samples obtained 0 to 48 h post-TDF-FTC dose had quantifiable FTC-TP in DBS, compared with 2/93 (2%) and 0/87 (0%) obtained >48 and >96 h postdose. In 746 paired plasma-DBS samples from 445 participants enrolled in PrEP trials, when both TFV/FTC in plasma were below the limit of quantification, FTC-TP was as well in 98.9% of the samples, and when either TFV or FTC in plasma was quantifiable, FTC-TP was as well in 90.5% of the samples. The half-life of FTC-TP in DBS is short relative to that of TFV-diphosphate (TFV-DP), making it a surrogate for TFV-FTC detection in plasma. FTC-TP can be quantified in DBS simultaneously with TFV-DP, which quantifies cumulative adherence to TDF-FTC. (The clinical trials discussed in this article have been registered at ClinicalTrials.gov under identifiers NCT01040091, NCT02022657, NCT00458393, NCT01772823, and NCT02012621.)
A Population and Developmental Pharmacokinetic Analysis To Evaluate and Optimize Cefotaxime Dosing Regimen in Neonates and Young Infants
Authors: Leroux Stéphanie , Roué Jean-Michel , Gouyon Jean-Bernard , Biran Valérie , Zheng Hao , Zhao Wei , Jacqz-Aigrain Evelyne
Published: August 2016

Cefotaxime is one of the most frequently prescribed antibiotics for the treatment of Gram-negative bacterial sepsis in neonates. However, the dosing regimens routinely used in clinical practice vary considerably. The objective of the present study was to conduct a population pharmacokinetic study of cefotaxime in neonates and young infants in order to evaluate and optimize the dosing regimen. An opportunistic sampling strategy combined with population pharmacokinetic analysis using NONMEM software was performed. Cefotaxime concentrations were measured by high-performance liquid chromatography-tandem mass spectrometry. Developmental pharmacokinetics-pharmacodynamics, the microbiological pathogens, and safety aspects were taken into account to optimize the dose. The pharmacokinetic data from 100 neonates (gestational age [GA] range, 23 to 42 weeks) were modeled with an allometric two-compartment model with first-order elimination. The median values for clearance and the volume of distribution at steady state were 0.12 liter/h/kg of body weight and 0.64 liter/kg, respectively. The covariate analysis showed that current weight, GA, and postnatal age (PNA) had significant impacts on cefotaxime pharmacokinetics. Monte Carlo simulations demonstrated that the current dose recommendations underdosed older newborns. A model-based dosing regimen of 50 mg/kg twice a day to four times a day, according to GA and PNA, was established. The associated risk of overdose for the proposed dosing regimen was 0.01%. We determined the population pharmacokinetics of cefotaxime and established a model-based dosing regimen to optimize treatment for neonates and young infants.
Potent Activities of Novel Imidazoles Lanoconazole and Luliconazole against a Collection of Azole-Resistant and -Susceptible Aspergillus fumigatus Strains
Authors: Abastabar Mahdi , Rahimi Nooshin , Meis Jacques F. , Aslani Narges , Khodavaisy Sadegh , Nabili Mojtaba , Rezaei-Matehkolaei Ali , Makimura Koichi , Badali Hamid
Published: August 2016

A collection of azole-susceptible (
n
= 141) and azole-resistant (
n
= 27)
Aspergillus fumigatus
isolates was tested against seven antifungal drugs, including the new imidazoles lanoconazole and luliconazole. The luliconazole and lanoconazole MIC
90
values for the azole-susceptible strains were 0.001 μg/ml and 0.008 μg/ml, and those for the azole-resistant strains were 0.016 μg/ml and 0.032 μg/ml.
Clinical Characteristics, Treatment Outcomes, and Resistance Mutations Associated with Macrolide-Resistant Mycobacterium avium Complex Lung Disease
Authors: Moon Seong Mi , Park Hye Yun , Kim Su-Young , Jhun Byung Woo , Lee Hyun , Jeon Kyeongman , Kim Dae Hun , Huh Hee Jae , Ki Chang-Seok , Lee Nam Yong , Kim Hong Kwan , Choi Yong Soo , Kim Jhingook , Lee Seung-Heon , Kim Chang Ki , Shin Sung Jae , Daley Charles L. , Koh Won-Jung
Published: August 2016

Macrolide antibiotics are key components of the multidrug treatment regimen for treating lung disease (LD) due to
Mycobacterium avium
complex (MAC). Despite the emergence of macrolide resistance, limited data are available on macrolide-resistant MAC-LD. This study evaluated the clinical features and treatment outcomes of patients with macrolide-resistant MAC-LD and the molecular characteristics of the macrolide-resistant isolates. A retrospective review of the medical records of 34 patients with macrolide-resistant MAC-LD who were diagnosed between January 2002 and December 2014 was performed, along with genetic analysis of 28 clinical isolates. Nineteen (56%) patients had the fibrocavitary form of MAC-LD, and 15 (44%) had the nodular bronchiectatic form.
M. intracellulare
was the etiologic organism in 21 (62%) patients. Approximately two-thirds (22/34 [65%]) of the patients had been treated with currently recommended multidrug regimens that included macrolide, ethambutol, and rifamycin prior to the emergence of macrolide resistance, and none had been treated with macrolide monotherapy. The median duration of treatment after the detection of macrolide resistance was 23.0 months (interquartile range, 16.8 to 45.3 months). Treatment outcomes were poor after the development of macrolide resistance, with favorable treatment outcomes achieved in only five (15%) patients, including two patients who underwent surgical resection. One-, 3-, and 5-year mortality rates were 9, 24, and 47%, respectively. Molecular analysis of 28 clinical isolates revealed that 96% (27/28) had point mutations at position 2058 or 2059 of the 23S rRNA gene. Our analyses indicate that more effective therapy is needed to treat macrolide-resistant MAC-LD and prevent its development.
IncHI2 Plasmids Are the Key Vectors Responsible for
oqxAB
Transmission among Salmonella Species
Authors: Wong Marcus Ho-yin , Chan Edward Wai-chi , Xie Liqi , Li Ruichao , Chen Sheng
Published: August 2016

This study reported and analyzed the complete sequences of two
oqxAB
-bearing IncHI2 plasmids harbored by a clinical
Salmonella enterica
serovar Typhimurium strain and an
S
. Indiana strain of animal origin, respectively. In particular, pA3T recovered from
S
. Indiana comprised the resistance determinants
oqxAB
,
aac(6′)Ib
-cr,
fosA3
, and
bla
CTX-M-14
. Further genetic screening of 63
oqxAB
-positive
Salmonella
isolates revealed that the majority carried IncHI2 plasmids, confirming that such plasmids play a pivotal role in dissemination of
oqxAB
in
Salmonella
spp.
Fur Represses Adhesion to, Invasion of, and Intracellular Bacterial Community Formation within Bladder Epithelial Cells and Motility in Uropathogenic Escherichia coli
Authors: Kurabayashi Kumiko , Agata Tomohiro , Asano Hirofumi , Tomita Haruyoshi , Hirakawa Hidetada
Published: August 2016

Uropathogenic
Escherichia coli
(UPEC) is a major pathogen that causes urinary tract infections (UTIs). This bacterium adheres to and invades the host cells in the bladder, where it forms biofilm-like polymicrobial structures termed intracellular bacterial communities (IBCs) that protect UPEC from antimicrobial agents and the host immune systems. Using genetic screening, we found that deletion of the
fur
gene, which encodes an iron-binding transcriptional repressor for iron uptake systems, elevated the expression of type I fimbriae and motility when UPEC was grown under iron-rich conditions, and it led to an increased number of UPEC cells adhering to and internalized in bladder epithelial cells. Consequently, the IBC colonies that the
fur
mutant formed in host cells were denser and larger than those formed by the wild-type parent strain. Fur is inactivated under iron-restricted conditions. When iron was depleted from the bacterial cultures, wild-type UPEC adhesion, invasion, and motility increased, similar to the case with the
fur
mutant. The purified Fur protein bound to regions upstream of
fimA
and
flhD
, which encode type I fimbriae and an activator of flagellar expression that contributes to motility, respectively. These results suggest that Fur is a repressor of
fimA
and
flhD
and that its repression is abolished under iron-depleted conditions. Based on our
in vitro
experiments, we conclude that UPEC adhesion, invasion, IBC formation, and motility are suppressed by Fur under iron-rich conditions but derepressed under iron-restricted conditions, such as in patients with UTIs.
Pediatric Hospitalizations for Inflammatory Bowel Disease Based on Annual Case Volume: Results from the Kids’ Inpatient Database 2012
Authors: Pant Chaitanya , Deshpande Abhishek , Sferra Thomas J , Almadhoun Osama , Batista Daisy , Pervez Asad , Nutalapati Venkat , Olyaee Mojtaba
Published: August 2016

To study differences related to pediatric inflammatory bowel disease (IBD) care among hospitals that were stratified based on annual case volume. This is a cross-sectional study using data from the United States Healthcare Cost and Utilization Project Kids’ Inpatient Database (KID). IBD-related hospitalizations were identified using International Classification of Diseases-9-Clinical Modification codes. Hospital volume was divided into low or high by assigning cut-off values of 1–20 and >20 annual IBD hospitalizations. We assessed a total of 8647 pediatric IBD discharges during 2012 from 660 hospitals in the USA. 107 of these hospitals were classified as high-volume centers (HVCs) for pediatric IBD care and 553 low-volume centers (LVCs). HVCs were more likely to be associated with an academic teaching status compared to LVCs (97.1% vs 67.6%, p<0.001). The incidence of transfer of medical care from LVCs to other hospitals was 5.5% but only 0.7% for HVCs (p<0.001). The median number of procedures (medical and surgical) performed on children admitted with IBD was higher at HVCs (2 vs 1, p<0.001). IBD admissions at HVCs were more likely to undergo surgical procedures compared to LVCs (17% vs 10%, p<0.001). The incidence of postoperative complications was not significantly different. There were significantly greater hospital costs (median US$11,000 vs US$6,000, p<0.001) and lengths of stay (median 5 days vs 4 days, p<0.001) associated with HVCs compared to LVCs. Pediatric admissions to HVCs for IBD undergo a greater number of medical and surgical procedures and are associated with higher costs and lengthier hospital stays.
Association of Statins with Diabetes Mellitus and Diabetic Complications: Role of Confounders During Follow-Up
Authors: Mansi Ishak A , Frei Christopher R , Halm Ethan A , Mortensen Eric M
Published: August 2016

Studies have associated statin use with increased risk of diabetes and diabetic complications. These studies often ensure comparability of statin users and non-users at baseline; however, most studies neglect to consider confounders that occur during follow-up. Failure to consider these confounders, such as new medications or procedures, may result in identification of a spurious association between statins and outcomes. The objective of this study was to examine the association of statins with diabetes mellitus and diabetic complications; and to examine potential confounders during the follow-up period that might affect this relationship. We conducted a retrospective cohort study using Tricare data (from October 1, 2003 to March 31, 2012). We propensity score-matched statin users and non-users on 115 baseline characteristics before starting statins; these characteristics would be potentially associated with the use of statins or the outcomes of interest. Outcomes included the risk of diabetes mellitus and diabetic complications. Out of 60,455 patients (10,910 statin users and 49,545 non-users), we propensity score-matched 6728 statin users to 6728 non-users. Statin users had higher ORs for diabetes (OR 1.34, 95% CI 1.24 to 1.44) and diabetes with complications (OR 1.28, 95% CI 1.16 to 1.42). Adjustment for potential confounders that occurred during the follow-up period did not explain or diminish the association between statins and adverse outcomes. Statin users in comparison to similar non-users were more commonly diagnosed with diabetes and diabetic complications, even after adjustment for potential confounders that occurred during the follow-up period.
The Ebola clinical trials: a precedent for research ethics in disasters
Authors: Calain Philippe
Published: August 2016

The West African Ebola epidemic has set in motion a collective endeavour to conduct accelerated clinical trials, testing unproven but potentially lifesaving interventions in the course of a major public health crisis. This unprecedented effort was supported by the recommendations of an ad hoc ethics panel convened in August 2014 by the WHO. By considering why and on what conditions the exceptional circumstances of the Ebola epidemic justified the use of unproven interventions, the panel's recommendations have challenged conventional thinking about therapeutic development and clinical research ethics. At the same time, unanswered ethical questions have emerged, in particular: (i) the specification of exceptional circumstances, (ii) the specification of unproven interventions, (iii) the goals of interventional research in terms of individual versus collective interests, (iv) the place of adaptive trial designs and (v) the exact meaning of compassionate use with unapproved interventions. Examination of these questions, in parallel with empirical data from research sites, will help build pragmatic foundations for disaster research ethics. Furthermore, the Ebola clinical trials signal an evolution in the current paradigms of therapeutic research, beyond the case of epidemic emergencies.
Improving herpetological surveys in eastern North America using the environmental DNA method
Authors: Lacoursière-Roussel Anaïs , Dubois Yohann , Normandeau Eric , Bernatchez Louis
Published: August 2016

Among vertebrates, herpetofauna has the highest proportion of declining species. Detection of environmental DNA (eDNA) is a promising method towards significantly increasing large-scale herpetological conservation efforts. However, the integration of eDNA results within a management framework requires an evaluation of the efficiency of the method in large natural environments and the calibration of eDNA surveys with the quantitative monitoring tools currently used by conservation biologists. Towards this end, we first developed species-specific primers to detect the wood turtle (Glyptemys insculpta) a species at risk in Canada, by quantitative PCR (qPCR). The rate of eDNA detection obtained by qPCR was also compared to the relative abundance of this species in nine rivers obtained by standardized visual surveys in the Province of Québec (Canada). Second, we developed multi-species primers to detect North American amphibian and reptile species using eDNA metabarcoding analysis. An occurrence index based on the distribution range and habitat type was compared with the eDNA metabarcoding dataset from samples collected in seven lakes and five rivers. Our results empirically support the effectiveness of eDNA metabarcoding to characterize herpetological species distributions. Moreover, detection rates provided similar results to standardized visual surveys currently used to develop conservation strategies for the wood turtle. We conclude that eDNA detection rates may provide an effective semiquantitative survey tool, provided that assay calibration and standardization is performed.
The Influence of Road Bumps Characteristics on the Chaotic Vibration of a Nonlinear Full-Vehicle Model with Driver
Authors: Fakhraei J. , Khanlo H. M. , Ghayour M. , Faramarzi Kh.
Published: August 2016

In this paper, the chaotic behavior of a ground vehicle system with driver subjected to road disturbances is studied and the relationship between the nonlinear vibration of the vehicle and ride comfort is evaluated. The vehicle system is modeled as fully nonlinear with seven degrees of freedom and an additional degree of freedom for driver (8-DOF). The excitation force is the road irregularities that are assumed as road speed control bumps. The sinusoidal, consecutive half-sine and dented-rectangular waveforms are considered to simulate the road speed control bumps. The nonlinearities of the system are due to the nonlinear springs and dampers that are used in the suspension system and tires. The governing differential equations are extracted under Newton–Euler laws and solved via numerical methods. The chaotic behaviors were studied in more detail with special techniques such as bifurcation diagrams, phase plane portrait, Poincaré map and Lyapunov exponents. The ride comfort was evaluated as the RMS value of the vertical displacement of the vehicle body and driver. Firstly, the effect of amplitude (height) and frequency (vehicle’s speed) of these speed control bumps on chaotic vibrations of vehicle are studied. The obtained results show that various forms of vibrations, such as periodic, subharmonic and chaotic vibrations, can be detected in the system behavior with the change of the height and frequency of speed control bumps and present different types of strange attractors in the vehicle with and without driver. Then, the influence of nonlinear vibration on ride comfort and the relationship between chaotic vibrations of the vehicle and driving comfort are investigated. The results of analyzing the RMS diagrams reveal that the chaotic behaviors can directly affect the driving comfort and lead to the driver’s comfort being reduced. The obtained results can be used in the design of vehicle and road bumps pavement.
Bifurcation, Synchronization, and Multistability of Two Interacting Networks with Multiple Time Delays
Authors: Mao Xiaochen
Published: August 2016

This paper reveals the dynamical properties of two interacting neural networks with multiple couplings. Different time delays are introduced into the nearest-neighbor links and long-range connections in each layer and the couplings between different substructures. The delay-dependent and delay-independent stability and the oscillations bifurcated from the trivial equilibrium of the network are analyzed. The conditions of the existence of nontrivial equilibria and pitchfork bifurcation are discussed. Numerical simulations are performed to validate the theoretical results and interesting neuronal activities are observed, such as completely synchronous oscillations, three types of asynchronous oscillations, multiple switches between the rest states and different oscillations, coexistence of different oscillations, and coexistence of nontrivial equilibria and oscillations.
Periodic Motions to Chaos in Pendulum
Authors: Luo Albert C. J. , Guo Yu
Published: August 2016

It is not easy to find periodic motions to chaos in a pendulum system even though the periodically forced pendulum is one of the simplest nonlinear systems. However, the inherent complex dynamics of the periodically forced pendulum is much beyond our imaginations through the traditional approach of linear dynamical systems. Until now, we did not know complex motions of pendulum yet. What are the mechanism and mathematics of such complex motions in the pendulum? The results presented herein give a new view of complex motions in the periodically forced pendulum. Thus, in this paper, periodic motions to chaos in a periodically forced pendulum are predicted analytically by a semi-analytical method. The method is based on discretization of differential equations of the dynamical system to obtain implicit maps. Using the implicit maps, mapping structures for specific periodic motions are developed, and the corresponding periodic motions can be predicted analytically through such mapping structures. Analytical bifurcation trees of periodic motions to chaos are obtained, and the corresponding stability and bifurcation analysis of periodic motions to chaos are carried out by eigenvalue analysis. From the analytical prediction of periodic motions to chaos, the corresponding frequency-amplitude characteristics are obtained for a better understanding of motions’ complexity in the periodically forced pendulum. Finally, numerical simulations of selected periodic motions are illustrated. The nontravelable and travelable periodic motions on the bifurcation trees are discovered. Through this investigation, the periodic motions to chaos in the periodically forced pendulums can be understood further. Based on the perturbation method, one cannot achieve the adequate solutions presented herein for periodic motions to chaos in the periodically forced pendulum.
Regulation of Hematopoiesis and Osteogenesis by Blood Vessel–Derived Signals
Authors: Ramasamy Saravana K. , Kusumbe Anjali P. , Itkin Tomer , Gur-Cohen Shiri , Lapidot Tsvee , Adams Ralf H.
Published: August 2016

In addition to their conventional role as a versatile transport system, blood vessels provide signals controlling organ development, regeneration, and stem cell behavior. In the skeletal system, certain capillaries support perivascular osteoprogenitor cells and thereby control bone formation. Blood vessels are also a critical component of niche microenvironments for hematopoietic stem cells. Here we discuss key pathways and factors controlling endothelial cell behavior in bone, the role of vessels in osteogenesis, and the nature of vascular stem cell niches in bone marrow.
The Mutualistic Niche: Mycorrhizal Symbiosis and Community Dynamics
Authors: Peay Kabir G.
Published: August 2016

The niche is generally viewed in terms of species' intrinsic physiological potential and limitations due to competition. Although DNA sequencing has revealed the ubiquity of beneficial microbial symbioses, the role of mutualisms in shaping species niches is not broadly recognized. In this review, I use a widespread terrestrial mutualism, the ectomycorrhizal symbiosis, to help develop the mutualistic niche concept. Using contemporary niche theory, I show how mycorrhizal symbioses expand environmental ranges (requirement niche) and influence resource use (impact niche) for both plants and fungi. Simple niche models for competition between resource specialists and generalists also predict a range of ecological phenomena, from unexpected monodominance by some tropical trees to the functional biogeography of mycorrhizal symbiosis. A niche-based view of mutualism may also help explain stability of mutualisms even in the absence of clear benefits. The niche is a central concept in ecology, and better integration of mutualism will more accurately reflect the positive interactions experienced by nearly all species.