bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal Effect on Electroosmotic Flow in a Slit Microchannel
Authors: Zhou Yi , Yang Chun , Zhao Cunlu
Published: December 2013

Electroosmotic flow (EOF) in microfluidic systems is frequently subjected to thermal effect because of temperature-dependent material properties. Boltzmann equation is usually used to describe the ion distribution in EOF. This study will compare the ion distribution under the thermal effect with the Boltzmann distribution. Moreover, for thin electrical double layer (EDL), constant potential model always be used to simplify the calculation of EOF at constant charge. In this study, the thermal effects on EOF at both constant potential and constant charge are analyzed. In addition, as the surface charge density increases largely with higher temperature, in this study efforts are also made to address the thermal effect on EOF induced by the temperature-dependent charge density.

In particular, a numerical model is presented for investigating the steady EOF under the thermal effect. The proposed model involves several coupled governing equations including the Nernst-Planck equations, the Poisson equation, the modified Navier-Stokes equations, and the energy equation. The simulation results show that the Boltzmann equation cannot fully describe the ionic concentration distributions under the large thermal effect when EDL overlap. Moreover, for thin EDL, the electroosmotic velocity under the thermal effect at constant potential is lower than that at constant charge, due to the negative electrothermal force at constant potential. Furthermore, it is revealed that the temperature-dependence of surface charge can significantly modify the characteristics of EOF.
A Photographic Study on the Effects of Hydrophobic-Spot Size and Subcooling on Local Film Boiling
Authors: Suroto Bambang Joko , Tashiro Masahiro , Hirabayashi Sana , Hidaka Sumitomo , Kohno Masamichi , Takahashi Koji , Takata Yasuyuki
Published: December 2013

The effects of hydrophobic circle spot size and subcooling on local film boiling phenomenon from the copper surface with single PTFE (Polytetrafluoroethylene) hydrophobic circle spot at low heat flux has been investigated. The experiments were performed using pure water as the working fluid and subcooling ranging from 0 and 10K. The heat transfer surfaces are used polished copper block with single PTFE hydrophobic circle spot of diameters 2, 4 and 6 mm, respectively. A high-speed camera was used to capture bubble dynamics and disclosed the sequence of the process leading to local film boiling. The result shows that local films boiling occurs on the PTFE circle spot at low heat flux and was triggered by the merging of neighboring bubbles. The study also showed that transition time required for change from nucleate boiling regime to local film boiling regime depends on the diameter of the hydrophobic circle spot and the subcooling. A stable local film boiling occurs at the smallest diameter of hydrophobic spot. Subcooling cause the local film boiling occur at negative superheat and oscillation of bubble dome.
Molecular Dynamics Study of Proton and Water Transport in Nafion Membrane
Authors: Mabuchi Takuya , Tokumasu Takashi
Published: December 2013

Polymer electrolyte fuel cells (PEFCs) are highly expected as a next-generation power supply system due to the purity of its exhaust gas, its high power density and high efficiency. The polymer electrolyte membrane is a critical component for the performance of the PEFCs and it is important to understand the nanostructure in the membrane to enhance proton transport. We have performed an atomistic analysis of the vehicular transport of hydronium ions and water molecules in the nanostructure of hydrated Nafion membrane by systematically changing the hydration level which provides insights into a connection between the nanoscopic and mesoscopic structure of ion clusters and the dynamics of hydronium ions and water molecules in the hydrated Nafion membrane. In this study, classical molecular dynamics simulations are implemented using a model of Nafion membrane which is based on DREIDING force field and newly modified and validated by comparing the density, water diffusivity, and Nafion morphology with experimental data. The simulated final density after the annealing procedure agrees with experiment within 1.3 % for various water contents and the trends that density decreases with increasing hydration level are reproduced. In addition to determination of diffusion coefficients of solvent molecules as a function of hydration level (from λ = 1 up to λ = 18), we have also calculated radial distribution functions and static structure factors not only to clarify the structure of water molecules and hydronium ions around the first solvation shell of sulfonate groups but also to validate the mesoscopic periodic structure among water clusters. The diffusion coefficient of water molecules increases with increasing hydration level and is found to be in good agreement with experimental data. The diffusion coefficient of hydronium ions has showed that general trends in the experimental data are reproduced by the simulations although the classical models have the limitation of probing hydronium dynamics. The static structure factors of liquid molecules at low wave length provide insights into the periodic structure of the inter-water clusters. These results are consistent with the Gebel’s model based on small-angle X-ray scattering that considers the dry membrane to be made of isolated spherical ionic clusters of radius ∼7.5 Å that swell with increasing hydration.
Measurement of Performance Characteristics of a Piezoelectric Micro Blower
Authors: Fukue Takashi , Hirose Koichi , Terao Hirotoshi
Published: December 2013

This study conducts a measurement system of a performance of a piezoelectric micro blower. Electronic equipments such as laptop computers and cellular phones become smaller and thinner while their functions become more complex. As a result, a lot of components are mounted in an electronic enclosure and flow passages for the cooling air become narrow. This causes significant pressure drop and general cooling fans cannot supply enough cooling air. To improve cooling performance in small electronic equipment, a new air supply system which combines smaller and thinner size with a high pressure performance characteristic is needed. We focused on a novel piezoelectric micro blower. This blower can supply the airflow with high static pressure using the vibration of the piezoelectric element. This may produce a forced convection cooling with low electric power regardless of the size of electronic equipment and packaging density of electrical devices. However, to predict accurate cooling performance of the piezoelectric micro blower in thermal design, we have to obtain a correct supply flow rate of the blower because the cooling performance of forced convection is significantly dependent on the supply flow rate. Generally, an operating point of the blower, which is the operating pressure and the flow rate in electronic equipment, is the point of intersection of performance characteristic curve, which is the relationship between the blower’s pressure rise and the supply flow rate, and flow resistance curve in equipment. Therefore the measurement of the performance characteristic curve is most important.

We tried to develop the measurement system of the performance characteristic curve of the piezoelectric micro blower with high accuracy. We succeeded to measure the relationship between the supply flow rate and the static pressure rise of the micro blower. Moreover, in order to clarify whether the micro blower is available for a cooling method of high-density packaging electronic equipment or not, we tried to investigate the effects of the obstruction, which is mounted in front of the blower, on the performance characteristic. Then, we confirmed whether the performance of the blower is changed by the components mounted near the blower or not.
Lattice Boltzmann Modeling for Analysis of Water-Splitting Over Nanorods With Emphasis on Reactive Mass Transport
Authors: Paradis Hedvig , Grigoropoulos Costas , Sundén Bengt
Published: December 2013

Lattice Boltzmann method (LBM) is an alternative to conventional CFD to capture the detailed activities of the transport processes at microscale. Here LBM is used to model the hydrogen production by splitting water by incident sunlight over water covered Si-nanorods. The purpose of this study is, by a 3D microscale model, to investigate the transport and the formation of the hydrogen bubbles by electrochemical reactions. An ordered array of nanorods is created where each rod is 10 μm high and 10 nm in diameter. The 3D model is simulated using parallel computing with the program Palabos. A multicomponent reaction-advection-diffusion transport for 3 components is analyzed with electrochemical reactions and this process is further coupled with the momentum transport.

It has here been shown that LBM can be used to evaluate the microscale effect of electrochemical reactions on the transport processes. An increased Bond number increase the bubble flow through the nanorod domain. A decreased contact angle facilitates the disconnection of the bubble to the nanorod at the top surface. The collection of the hydrogen bubbles at the top surface of the nanorods will be facilitated by an easy disconnection of the bubbles.
Recent Developments in Micro/Nanochannel Emulsification for Controlled Production of Monodisperse Emulsions
Authors: Kobayashi Isao , Butron Fujiu Katerina , Neves Marcos A. , Nakajima Mitsutoshi
Published: December 2013

Microfluidic techniques for producing emulsions have been proposed over the last decade. Major advantages of microfluidic techniques include the production of monodisperse emulsions with a coefficient of variation (CV) of typically <5%, superior controllability of droplet size and monodispersity, and in situ microscopic monitoring. Microchannel (MC) emulsification, proposed by our research group, is a unique and robust technique to produce monodisperse emulsions with controlled droplet sizes of >1 μm. In MC emulsification, droplet generation via MC arrays does not require any external shear/elongational stress; i.e., the dispersed phase that passed through MCs is transformed spontaneously into uniform droplets due to hydrodynamic instability of the oil-water interface. Here we present some of the recent findings obtained from MC emulsification studies and the controlled production of monodisperse submicron emulsions by novel nanochannel (NC) emulsification. The first topic on MC emulsification is the influence of operating temperature (10 to 70 °C) on production of oil-in-water (O/W) emulsions using a surface-oxidized silicon MC array plate with an MC depth of 8 μm. The droplet generation results were correlated well with the contact angle of the dispersed phase to the MC walls that was measured using a novel method using parallel long MCs. Another topic on MC emulsification is the development of stainless-steel MC emulsification devices. Stainless-steel MC array plates with an MC depth of 100 or 150 μm were mechanically fabricated using an end mill. The use of the stainless-steel MC array plates enabled stably producing monodisperse O/W emulsions with an average droplet diameter of up to 550 μm. We also recently developed silicon NC array plates with the smallest NC depth of 50 nm. NC emulsification experiments demonstrated successful production of monodisperse submicron O/W emulsions with the smallest average droplet diameter of 480 nm. The diameter of the droplets generated by NC emulsification was measured by a novel technique that exploits nanospace.
Three Dimensional Thermo-Fluid Analyses on Convective Heat Transfer and Friction Loss in Micro/Mini Channel Based on High Order LES Model
Authors: Biswas Debasish , Kitoh Aya
Published: December 2013

Several researches dealing with the single-phase forced convection heat transfer in micro tubes have been published in the past years. Most of their tests results are significantly departed from those of the traditional forced convection heat transfer coefficients in larger tubes. Some recent work reported that measurement accuracy is one of the most important factors that may cause this discrepancy. Since the diameter of the sensor for measuring micro tubes surface temperature is comparable to the size of the micro-tubes, the tubes surface temperature can not be accurately measured due to the effect of sensor wire thermal shunt. In this work some recent experimental results on heat transfer and frictional losses in mini/micro channel of semi-circular configurations using water as working fluid are investigated numerically by comparing the measured and predicted data. The flow conditions considered here cover a wide range of Reynolds number (300–4000), which corresponds to laminar, transitional and turbulent flow. Since the flow considered here is turbulent in nature emphasis is put on the physics based turbulent model. In this study, a high order LES turbulent model in which in a dynamic eddy viscosity model, transfer of information between the sub-grid and large scale eddies is improved by solving an additional transport equation for turbulent kinetic energy in the grid scale level. Here, sub-grid-scale turbulent stresses are closed using a dynamic turbulent kinetic energy transport model. The sub-grid scale length scale is represented by the minimum of the universal length scale lu and the grid scale. The universal length scale lu, which represents the blending of the length scales of cascade of eddies starting from the near wall small scale all the way to the sub-grid scale, is defined on the basis of turbulent Reynolds number Ret. A test filter was used for the dynamic procedure, which is applicable to stretched grid near the body surface. Also the thermal convection problem is coupled with thermal conduction within the material to obtain the overall solution. Predicted results agreed well with the measured data. The results helped to have a good understanding of how the flow and thermal phenomena attributed to the overall heat transfer and frictional loss mechanism. The comparison of measured and predicted data based on single phase N-S equations showed a very good agreement and the visualization of the three-dimensional results of computation led to a good understanding of the physics based mechanism associated with the laminar to turbulent transitional phenomena inside the micro/mini channels.
Improvement of Physical-Mechanical Properties of the Composite Materials in Aircraft Structure Using Carbon Nanomaterial Based on Phenolic Binder and Fiberglass
Authors: Alhussan Khaled
Published: December 2013

Aggregate stability of “carbon nanotube-polymer matrix” depends on the specific features of Surface tube and surrounding polymer interaction, i.e. The behavior of nanocarbon particles assembly in each particular system. This work is provided with the conditions of used carbon nanomaterial treatment for the improvement of its aggregate stability when introducing into phenolic matrix.

Multiwall carbon carbon nanotubes and nanofibers possess unique properties which allow to constantly widen the spheres of their practical application. Recently there have appeared a lot of works dedicated to the creation of composite materials with the improved properties via CNM introduction into various polymers [1, 2].

However until the present time it was impossible to fulfill the possibilities of the application of carbon materials as modified additives completely. As carbon nanotubes and nanofibers are very small and possess high surface energy they easily form agglomerates with tens of microns sizes which reduce the efficiency of additive and matrix interaction.
Subcooled Flow Boiling Over Nanostructured Plate Integrated Into a Rectangular Channel
Authors: Demir Ebru , Sesen Muhsincan , Izci Turker , Khudhayer Wisam , Karabacak Tansel , Kosar Ali
Published: December 2013

Sub-cooled flow boiling was investigated over nanostructured plate (of dimensions 20mm×20mm) integrated to a rectangular channel (of dimensions 33mm×9mm×33mm) at flow rates ranging from 69 ml/min to 145 ml/min. The configuration of the nanostructured plate includes ∼600 nm long copper nanorod arrays with an average nanorod diameter of ∼150 nm. The nanorod arrays are integrated to copper thin film (∼300 nm thick) coated on silicon wafer surface and GLAD (Glancing Angle Deposition) technique was implemented to form the nanostructure configuration. The dimensions and flow rates were chosen to ensure that no change in the nanostructure configurations occurred during the experiments so that the configuration could be used for many experiments. For this, applied heat fluxes (<42 W/cm2) were adjusted in such a way that the wall superheats did not exceed 30°C to avoid any damage on nanostructures. Deionized-water was propelled with a gear pump into the rectangular channel over plates with both plain and nanostructured surface, which were heated with cartridge heaters. Forced convective boiling heat transfer characteristics of the nanostructured plate is investigated using the experimental setup and compared to the results from the plate with plain surface. A significant increase in boiling heat transfer was observed with the nanostructured plate. In the light of the obtained promising results, channels with nanostructured surfaces were proven to be useful particularly in various applications such as cooling of small electronic devices, where conventional surface enhancement techniques are not applicable.
Numerical Investigation on Interfacial Phenomena of Ferrofluid by Lattice Boltzmann Method
Authors: Zhou Wenning , Yan Yuying , Luo Xiaoping
Published: December 2013

Ferrofluid, also known as magnetic fluid, is a new-type fluid whose property and morphology can be controlled by the external magnetic field. It mainly consists of carrier fluid and suspended magnetic particles (diameter usually 10 nanometers or less). Ferrofluids behave as a smart or functional fluid and has been finding more and more applications in a variety of fields such as electronic packing, mechanical engineering, aerospace, bioengineering, and thermal engineering. It has therefore recently attracted many researchers’ interest. Due to the nanosize particles and complex interactions between the nanoparticles and carrier fluid, it is difficult to get insights into ferrofluid by pure experimental or theoretical study. To fully understand the mechanism of ferrofluid, efficient and robust computational methods for the numerical simulation of their dynamical behavior are constantly in high demand. Several numerical models have been proposed for ferrofluid. Over the last decade, lattice Boltzmann method, a new mesoscopic approach, has emerged as a powerful tool for the numerical investigation of a broad class of complex flow, including multicomponent and multiphase flows. Compared with other numerical methods, lattice Boltzmann method, which is based on kinetic theory, has advantages to deal with the interfacial interactions of multiphase flow in micro/nano scale.

In the present study, we present a multicomponent lattice Boltzmann model to simulate ferrofluid. In this model, the interactions between internal and external forces of ferrofluid are considered. To validate the coupling of the magnetic field, the velocity field and the evolution of the interface, the steady-state shape of the ferrofluid droplet is analysed. Then the influence of the external magnetic field on the ferrofluid droplet formation and deformation process is numerically investigated. The parameters affecting the interfacial phenomena of ferrofluid, including the magnetic Bond number and the susceptibility, are discussed in this paper. The change in the droplet size and the magnetic strength is simulated. The simulation results show the ferrofluid droplet size increases with increasing magnetic strength. All the results are also compared with previous numerical or experimental studies. The simulation results presented in this paper indicate that lattice Boltzmann method is a capable method to study complex magnetic fluid phenomena. It is also hoped that the simulation results offer helpful information on controlling ferrofluid in our practical applications.
Visualization of Boiling Heat Transfer on Micro Porous Coated Surface in Confined Space
Authors: Yang Chien-Yuh , Liu Chien-Fu
Published: December 2013

Numerous researches have been developed for pool boiling on microporous coated surface in the past decade. The nucleate boiling heat transfer was found to be increased by up to 4.5 times than that on uncoated surface. Recently, the two-phase micro heat exchangers have been considered for high flux electronic devices cooling. The enhancement techniques for improving the nucleate boiling heat transfer performance in the micro heat exchangers have gotten more importance. Previous studies of microporous coatings, however, have been restricted to boiling in unconfined space. No studies have been made on the feasibility of using microporous coatings for enhancing boiling in confined spaces. This study provides an experimental observation of the vapor generation and leaving processes on microporous coatings surface in a 1-mm confined space. It would be helpful for understanding the mechanism of boiling heat transfer and improving the design of two-phase micro heat exchangers.

Aluminum particles of average diameter 20 μm were mixed with a binder and a carrier to develop a 150 μm thickness boiling enhancement paint on a 3.0 cm by 3.0 cm copper heating surface. The heating surface was covered by a thin glass plate with a 1 mm spacer to form a 1 mm vertical narrow space for the test section. The boiling phenomenon was recorded by a high speed camera. In addition to the three boiling regimes observed by Bonjour and Lallemand [1], i.e., isolated deformed bubbles, coalesced bubbles and partial dryout at low, moderate and high heat fluxes respectively in unconfined space, a suction and blowing process was observed at the highest heat flux condition. Owing to the space confinement, liquid was sucked and vapor was expelled periodically during the bubble generation process. This mechanism significantly enhanced the boiling heat transfer performance in confined space.
Numerical Investigation of Coalescence of Viscous Particles With Solid Cores
Authors: Dayal Ram , Abele Eberhard , Gambaryan-Roisman Tatiana
Published: December 2013

Coalescence of viscous particles with solid cores plays an important role in chemical and pharmaceutical industry, in agriculture and in production technology. Coalescence of metal particles, which are partially melted due the laser heating, is an important mechanism responsible for densification of metal powder during selective laser sintering process.

Our model describes coalescence of two or more particles consisting of a solid core and a liquid shell. The flow in the liquid shell is driven by the surface tension. It is assumed that the characteristic Reynolds number is low, so that the creeping flow model can be applied. A two dimensional boundary element model (BEM) is used to solve the governing equations. The numerical model is validated by comparison with available analytical solution for the limiting case of fully viscous particles.

The influence of the liquid properties, the sizes of the particles and the relative sizes of the solid core on the two-phase flow and on the shape evolution of coalescing particles is quantified. In application to the selective laser sintering process densification rate has been defined as an important output parameter. We show that increasing of the solid core radius leads to the decrease of the powder densification rate.
3D Focusing of Microparticles by Acoustic Standing Waves in a Flow Through Channel
Authors: Iorio C. S. , Perfetti C. , Vancauwenberghe V. , Dubois F.
Published: December 2013

Analysis of environmental changes has become a great issue nowadays with the increase of pollution and global warming. Surveys about growing populations of species and apparition of new parasites are more and more relevant to preserve our environment and populations needs. The ability to observe for instance the presence of bacteria such as Criptosporidium and Giardia Lamblia in freshwater contributes to prevent people from diseases even in developed countries. The main issue in the observation of such species is that the size of the biological sample should be large enough to be representative of its surrounding environment, meaning that the amount of the scanned sample is several orders superior to the size of the micro species of interest.

A major limitation for optical instruments in performing this kind of analysis is that the magnification required should fit the size of the particles, severely constraining the field of view. As a result, the rate of analysis is often so slow to be compatible with the large samples to analyze.

One way to increase the rate of analysis is to manipulate particles in order to focus them in the field of view of the visualization system.

In this article we use acoustic standing waves to achieve this goal by directing particles in the observation region.

A 1mm × 1mm square section glass channel, excited by a piezo transducer is used. The carrier fluid is water while several types of particles, both synthetic and biological are tested. The dynamic behaviour of particles under the acoustic field has been investigated and the 3D position of each particle is reported.

In order to increase the depth of investigation, we used a Digital Holographic Microscope. This technology permit to scan a larger volume of fluid and also to calculate the 3D position of each detected particle flowing in the channel.

A focusing streamline of as thin as 1/20 of the channel cross section has been successfully achieved.
Vertical Falling Film Evaporation of Pure Refrigerant HCFC123 in a Plate-Fin Heat Exchanger
Authors: Ohara Junichi , Koyama Shigeru
Published: December 2013

The characteristics of heat transfer and flow patterns are investigated experimentally for the vertical falling film evaporation of pure refrigerant HCFC123 in a rectangular minichannels consisting of offset strip fins. The refrigerant liquid is uniformly supplied to the channel through a distributor. The liquid flowing down vertically is heated electrically from the rear wall of the channel and evaporated. To observe the flow patterns during the evaporation process directly, a transparent vinyl chloride resin plate is placed as the front wall. The experimental parameters are as follows: the mass velocity G = 28∼70 kg/(m2s), the heat flux q = 20∼50 kW/m2 and the pressure P ≈ 100 kPa. It is clarified that the heat transfer coefficient α depends on G and q in the region of vapor quality x ≥ 0.3 while there is little influence of G and q in the region x ≤ 0.3. From the direct observation using a high speed video camera and a digital still camera, flow patterns are classified into five types. Then the empirical correlation equations for evaporation heat transfer coefficient on a vertical falling film plate fin evaporator with minichannels are proposed. From the physical model to evaluate the heat transfer coefficient of the minichannel surface with fins, the characteristics of fin efficiency is clarified that the average value of fin efficiency is about 0.6 and the distributive characteristics of fin efficiency is roughly inverse of heat transfer coefficient characteristics.
Laser-Based Measurement Techniques for Interfacial Transport Phenomena in Microchannels
Authors: Hishida Koichi , Ichiyanagi Mitsuhisa , Kazoe Yutaka , Sato Yohei
Published: December 2013

This paper summarized our recent works of the laser-based measurement techniques for investigating micro- and nano-scale transport phenomena. Micron-resolution particle image velocimetry combined with the laser induced fluorescence (LIF) technique was developed for analyzing velocity and ion concentration distributions simultaneously. The measurement system was based upon a confocal microscopy to realize the depth-resolution of approximately 2 μm, and this technique was applied to liquid-liquid mixing flows, gas-liquid two-phase flows and gas permeation phenomena through membranes. To evaluate the electrostatic potential at solid-liquid interface (i.e., zeta-potential), the LIF technique was advanced with the evanescent wave illumination. Fluorescent dye within approximately 100 nm from a microchannel wall was irradiated. This technique was applied to microdevices with a surface modification pattern, and the zeta-potential distribution was successfully visualized. Two proposed techniques will contribute to novel applications related to microscale multiphase flows or electrokinetics.
Hedgehog Signaling Controls T Cell Killing at the Immunological Synapse
Authors: de la Roche Maike , Ritter Alex T. , Angus Karen L. , Dinsmore Colin , Earnshaw Charles H. , Reiter Jeremy F. , Griffiths Gillian M.
Published: December 2013

Hedgehog View to a Kill

Hedgehog (Hh) signaling is best known for its role in development and is a key signaling component of primary cilia. Hh signaling plays a role in T cell development, but whether Hh signaling plays a role in the function of mature effector T cells is unclear.

De la Roche
et al.

(p.
1247
; see the Perspective by

Le Borgne and Shaw

) now show that T cell receptor signaling triggers Hh signaling. When Hh signaling is disrupted, centrosome polarization to the immunological synapse is reduced, and cytotoxic T cell–mediated killing is impaired.
Comment on “Poverty Impedes Cognitive Function”
Authors: Wicherts Jelte M. , Scholten Annemarie Zand
Published: December 2013

Mani
et al
. (Research Articles, 30 August, p. 976) presented laboratory experiments that aimed to show that poverty-related worries impede cognitive functioning. A reanalysis without dichotomization of income fails to corroborate their findings and highlights spurious interactions between income and experimental manipulation due to ceiling effects caused by short and easy tests. This suggests that effects of financial worries are not limited to the poor.
From Persistence to Cross-Species Emergence of a Viral Zoonosis
Authors: Streicker Daniel G.
Published: December 2013

Interdisciplinary research on zoonotic pathogens illuminates ecology and evolution, while guiding disease prevention and control.
Adrenergic Regulation of Antibodies
Authors: Foley John F.
Published: December 2013

Primed B cells stimulated through the β
2
-adrenergic receptor release exosomes that enhance IgE production by recipient B cells.
Cholesterol and Cancer
Authors: Kiberstis Paula A.
Published: December 2013

The activity of a specific metabolite of cholesterol may help explain why obesity is a risk factor for breast cancer.
Neuronal Activity and Dendrite Development
Authors: Hines Pamela J.
Published: December 2013

High-acuity sensory function may be achieved by the tuning of subcellular polarity to sources of high sensory activity.
Raltegravir Has a Low Propensity To Cause Clinical Drug Interactions through Inhibition of Major Drug Transporters: an
In Vitro
Evaluation
Authors: Rizk Matthew L. , Houle Robert , Chan Grace Hoyee , Hafey Mike , Rhee Elizabeth G. , Chu Xiaoyan
Published: December 2013

Raltegravir (RAL) is a human immunodeficiency virus type 1 (HIV-1) integrase inhibitor approved to treat HIV infection in adults in combination with other antiretrovirals. The potential of RAL to cause transporter-related drug-drug interactions (DDIs) as an inhibitor has not been well described to date. In this study, a series of
in vitro
experiments were conducted to assess the inhibitory effects of RAL on major human drug transporters known to be involved in clinically relevant drug interactions, including hepatic and renal uptake transporters and efflux transporters. For hepatic uptake transporters, RAL showed no inhibition of organic anion-transporting polypeptide 1B1 (OATP1B1), weak inhibition of OATP1B3 (40% inhibition at 100 μM), and no inhibition of organic cation transporter 1 (OCT1). Studies of renal uptake transporters showed that RAL inhibited organic anion transporters 1 and 3 (OAT1 and OAT3) with 50% inhibitory concentrations (IC
50
s) (108 μM and 18.8 μM, respectively) well above the maximum concentration of drug in plasma (
C
max
) at the clinical 400-mg dose and did not inhibit organic cation transporter 2 (OCT2). As for efflux transporters, RAL did not inhibit breast cancer resistance protein (BCRP) and showed weak inhibition of multidrug and toxin extrusion protein 1 (MATE1) (52% inhibition at 100 μM) and MATE2-K (29% inhibition at 100 μM). These studies indicate that at clinically relevant exposures, RAL does not inhibit or only weakly inhibits hepatic uptake transporters OATP1B1, OATP1B3, and OCT1, renal uptake transporters OCT2, OAT1, and OAT3, as well as efflux transporters BCRP, MATE1, and MATE2-K. The propensity for RAL to cause DDIs via inhibition of these transporters is therefore considered low.
Phenotypic Profiling of Antibiotic Response Signatures in Escherichia coli Using Raman Spectroscopy
Authors: Athamneh A. I. M. , Alajlouni R. A. , Wallace R. S. , Seleem M. N. , Senger R. S.
Published: December 2013

Identifying the mechanism of action of new potential antibiotics is a necessary but time-consuming and costly process. Phenotypic profiling has been utilized effectively to facilitate the discovery of the mechanism of action and molecular targets of uncharacterized drugs. In this research, Raman spectroscopy was used to profile the phenotypic response of
Escherichia coli
to applied antibiotics. The use of Raman spectroscopy is advantageous because it is noninvasive, label free, and prone to automation, and its results can be obtained in real time. In this research,
E. coli
cultures were subjected to three times the MICs of 15 different antibiotics (representing five functional antibiotic classes) with known mechanisms of action for 30 min before being analyzed by Raman spectroscopy (using a 532-nm excitation wavelength). The resulting Raman spectra contained sufficient biochemical information to distinguish between profiles induced by individual antibiotics belonging to the same class. The collected spectral data were used to build a discriminant analysis model that identified the effects of unknown antibiotic compounds on the phenotype of
E. coli
cultures. Chemometric analysis showed the ability of Raman spectroscopy to predict the functional class of an unknown antibiotic and to identify individual antibiotics that elicit similar phenotypic responses. Results of this research demonstrate the power of Raman spectroscopy as a cellular phenotypic profiling methodology and its potential impact on antibiotic drug development research.
Immunological Characterization of a Modified Vaccinia Virus Ankara Vector Expressing the Human Papillomavirus 16 E1 Protein
Authors: Remy-Ziller Christelle , Germain Claire , Spindler Anita , Hoffmann Chantal , Silvestre Nathalie , Rooke Ronald , Bonnefoy Jean-Yves , Préville Xavier
Published: December 2013

Women showing normal cytology but diagnosed with a persistent high-risk human papillomavirus (HR-HPV) infection have a higher risk of developing high-grade cervical intraepithelial neoplasia and cervical cancer than noninfected women. As no therapeutic management other than surveillance is offered to these women, there is a major challenge to develop novel targeted therapies dedicated to the treatment of these patients. As such, E1 and E2 antigens, expressed early in the HPV life cycle, represent very interesting candidates. Both proteins are necessary for maintaining coordinated viral replication and gene synthesis during the differentiation process of the epithelium and are essential for the virus to complete its normal and propagative replication cycle. In the present study, we evaluated a new active targeted immunotherapeutic, a modified vaccinia virus Ankara (MVA) vector containing the E1 sequence of HPV16, aimed at inducing cellular immune responses with the potential to help and clear persistent HPV16-related infection. We carried out an extensive comparative time course analysis of the cellular immune responses induced by different schedules of immunization in C57BL/6 mice. We showed that multiple injections of MVA-E1 allowed sustained HPV16 E1-specific cellular immune responses in vaccinated mice and had no impact on the exhaustion phenotype of the generated HPV16 E1-specific CD8+T cells, but they led to the differentiation of multifunctional effector T cells with high cytotoxic capacity. This study provides proof of concept that an MVA expressing HPV16 E1 can induce robust and long-lasting E1-specific responses and warrants further development of this candidate.
The 3′ Overhangs at Tetrahymena thermophila Telomeres Are Packaged by Four Proteins, Pot1a, Tpt1, Pat1, and Pat2
Authors: Premkumar Vidjaya Letchoumy , Cranert Stacey , Linger Benjamin R. , Morin Gregg B. , Minium Sasha , Price Carolyn
Published: December 2013

Although studies with the ciliate
Tetrahymena thermophila
have played a central role in advancing our understanding of telomere biology and telomerase mechanisms and composition, the full complement of
Tetrahymena
telomere proteins has not yet been identified. Previously, we demonstrated that in
Tetrahymena
, the telomeric 3′ overhang is protected by a three-protein complex composed of Pot1a, Tpt1, and Pat1. Here we show that Tpt1 and Pat1 associate with a fourth protein, Pat2 (Pot1 associated
Tetrahymena
2). Mass spectrometry of proteins copurifying with Pat1 or Tpt1 identified peptides from Pat2, Pot1a, Tpt1, and Pat1. The lack of other proteins copurifying with Pat1 or Tpt1 implies that the overhang is protected by a four-protein Pot1a-Tpt1-Pat1-Pat2 complex. We verified that Pat2 localizes to telomeres, but we were unable to detect direct binding to telomeric DNA. Cells depleted of Pat2 continue to divide, but the telomeres exhibit gradual shortening. The lack of growth arrest indicates that, in contrast to Pot1a and Tpt1, Pat2 is not required for the sequestration of the telomere from the DNA repair machinery. Instead, Pat2 is needed to regulate telomere length, most likely by acting in conjunction with Pat1 to allow telomerase access to the telomere.
Defects in the Flagellar Motor Increase Synthesis of Poly-γ-Glutamate in Bacillus subtilis
Authors: Chan Jia Mun , Guttenplan Sarah B. , Kearns Daniel B.
Published: December 2013

Bacillus subtilis
swims in liquid media and swarms over solid surfaces, and it encodes two sets of flagellar stator homologs. Here, we show that
B. subtilis
requires only the MotA/MotB stator during swarming motility and that the residues required for stator force generation are highly conserved from the
Proteobacteria
to the
Firmicutes
. We further find that mutants that abolish stator function also result in an overproduction of the extracellular polymer poly-γ-glutamate (PGA) to confer a mucoid colony phenotype. PGA overproduction appeared to be the result of an increase in the expression of the
pgs
operon that encodes genes for PGA synthesis. Transposon mutagenesis was conducted to identify insertions that abolished colony mucoidy and disruptions in known transcriptional regulators of PGA synthesis (Com and Deg two-component systems) as well as mutants defective in transcription-coupled DNA repair (Mfd)-reduced expression of the
pgs
operon. A final class of insertions disrupted proteins involved in the assembly of the flagellar filament (FliD, FliT, and FlgL), and these mutants did not reduce expression of the
pgs
operon, suggesting a second mechanism of PGA control.
Two Novel Proteins of Cyanophage Syn5 Compose Its Unusual Horn Structure
Authors: Raytcheva Desislava A. , Haase-Pettingell Cameron , Piret Jacqueline , King Jonathan A.
Published: December 2013

The marine cyanophage Syn5 can be propagated to a high titer in the laboratory on marine photosynthetic
Synechococcus
sp. strain WH8109. The purified particles carry a novel slender horn structure projecting from the vertex opposite the tail vertex. The genome of Syn5 includes a number of genes coding for novel proteins. Using immune-electron microscopy with gold-labeled antibodies, we show that two of these novel proteins, products of genes 53 and 54, are part of the horn structure. A third novel protein, the product of gene 58, is assembled onto the icosahedral capsid lattice. Characterization of radioactively labeled precursor procapsids by sucrose gradient centrifugation shows that there appear to be three classes of particles—procapsids, scaffold-deficient procapsids, and expanded capsids. These lack fully assembled horn appendages. The horn presumably assembles onto the virion just before or after DNA packaging. Antibodies raised to the recombinant novel Syn5 proteins did not interfere with phage infectivity, suggesting that the functions of these proteins are not directly involved in phage attachment or infection of the host WH8109. The horn structure may represent some adaption to the marine environment, whose function will require additional investigation.
Internal Ribosome Entry Site-Based Attenuation of a Flavivirus Candidate Vaccine and Evaluation of the Effect of Beta Interferon Coexpression on Vaccine Properties
Authors: Frese Michael , Lee Eva , Larena Maximilian , Lim Pek Siew , Rao Sudha , Matthaei Klaus I. , Khromykh Alexander , Ramshaw Ian , Lobigs Mario
Published: December 2013

Infectious clone technologies allow the rational design of live attenuated viral vaccines with the possibility of vaccine-driven coexpression of immunomodulatory molecules for additional vaccine safety and efficacy. The latter could lead to novel strategies for vaccine protection against infectious diseases where traditional approaches have failed. Here we show for the flavivirusMurray Valley encephalitis virus(MVEV) that incorporation of the internal ribosome entry site (IRES) ofEncephalomyocarditis virusbetween the capsid and prM genes strongly attenuated virulence and that the resulting bicistronic virus was both genetically stable and potently immunogenic. Furthermore, the novel bicistronic genome organization facilitated the generation of a recombinant virus carrying an beta interferon (IFN-β) gene. Given the importance of IFNs in limiting virus dissemination and in efficient induction of memory B and T cell antiviral immunity, we hypothesized that coexpression of the cytokine with the live vaccine might further increase virulence attenuation without loss of immunogenicity. We found that bicistronic mouse IFN-β coexpressing MVEV yielded high virus and IFN titers in cultured cells that do not respond to the coexpressed IFN. However, in IFN response-sufficient cell cultures and mice, the virus produced a self-limiting infection. Nevertheless, the attenuated virus triggered robust innate and adaptive immune responses evidenced by the induced expression of Mx proteins (used as a sensitive biomarker for measuring the type I IFN response) and the generation of neutralizing antibodies, respectively.

IMPORTANCEThe familyFlaviviridaeincludes a number of important human pathogens, such asDengue virus,Yellow fever virus,Japanese encephalitis virus,West Nile virus, andHepatitis C virus. Flaviviruses infect large numbers of individuals on all continents. For example, as many as 100 million people are infected annually withDengue virus, and 150 million people suffer a chronic infection withHepatitis C virus. However, protective vaccines against dengue and hepatitis C are still missing, and improved vaccines against other flaviviral diseases are needed. The present study investigated the effects of a redesigned flaviviral genome and the coexpression of an antiviral protein (interferon) on virus replication, pathogenicity, and immunogenicity. Our findings may aid in the rational design of a new class of well-tolerated and safe vaccines.
Pneumatosis intestinalis associated with enteral tube feeding
Authors: Zorgdrager Marcel , Pol Robert
Published: December 2013

A 49-year-old man presented with a Hinchey II perforated diverticulitis and underwent laparoscopic peritoneal lavage. During the postoperative course the patient received enteral tube feeding which was followed by a bowel obstruction accompanied with pneumatosis intestinalis (PI). Explorative laparotomy showed an omental band adhesion without signs of ischaemia. After a short period of total parenteral nutrition PI resolved almost completely and enteral tube feeding could be continued once again. In the weeks that followed the patient developed atypical bowel symptoms and recurrent PI which resolved each time the drip feeding was discontinued. Despite the mild clinical course, a CT scan showed massive PI on day 21 after the laparotomy. After excluding life-threatening conditions conservative management was instituted and the patient recovered completely after discontinuing the drip feeding. We present one of the few cases of subclinical PI associated with enteral tube feeding that could be managed conservatively.
Orbital apex syndrome secondary to granulomatosis with polyangiitis
Authors: Siddiqui Sarah , Kinshuck Andrew Jon , Srinivasan Venkat Ramanan
Published: December 2013

Orbital apex syndrome (OAS) is an optic nerve dysfunction with palsy of the third, fourth and sixth cranial nerves and ophthalmic division of the fifth cranial nerve. Causes can be infective, inflammatory, traumatic, neoplastic or vasculitic. We describe the first case in British literature and second worldwide of OAS presenting as granulomatosis with polyangiitis (GPA). A 38-year-old patient presented with left periorbital swelling and pain. An examination revealed left eye proptosis, tenderness in the ophthalmic distribution of the trigeminal nerve, unilateral ophthalmoplegia and reduced visual acuity. Initial treatment included intravenous antibiotics, steroids and nasal decongestants.Imaging demonstrated sinusitis and a suspected abscess from the infratemporal fossa to the orbital apex. However, sinus surgery showed granulation tissue without pus. The biopsy result was highly suggestive of GPA. A subsequent vasculitic screen was cytoplasmic-antineutrophil cytoplasmic antibody positive.This case highlights an unusual presentation of OAS secondary to GPA, as initial features suggested an infective cause.
Oral health management of a patient with 47,XYY syndrome
Authors: Shah Altaf Hussain , Manjunatha B S , Bindayel Naif A , Khounganian Rita
Published: December 2013

The 47,XYY syndrome is an aneuploidy (abnormal number) of sex chromosomes, where a human male receives an extra Y chromosome, making 47 chromosomes instead of the usual 46. Individuals with 47,XYY are usually physically normal and tend to be tall and thin. They are not at increased risk of mental retardation and cardiovascular diseases. They may have speech delay, hyperactivity and normal/decreased IQ level. Behavioural problems are not common in 47,XYY individuals. There have been reports that suggest the tooth-size increase in 47,XYY males is due to a direct genetic effect. The patient presented with multiple over-retained deciduous, unerupted permanent teeth and increased incidence of carious lesions may be attributed to decreased oral hygiene maintenance. The present article describes the medical and dental history along with the clinical management of oral health issues in an 18-year-old male patient with 47,XYY syndrome having normal physical structure and development.