bluuebunny/crossref_metadata_2025 huggingface dataset:
RPM-Synchronous Grinding: Control Concepts to Improve Surface Qualities for a Highly Efficient Non-Circular Grinding Approach
Authors: Steffan Matthias , Haas Franz , Spenger Thomas
Published: January 2018

The RPM-Synchronous Grinding process offers new possibilities to generate defined macro- and micro-geometries on workpieces. With present technology, various macroscopic non-circular geometries must be grinded subsequently in an oscillating process where the X-axis is coupled with the rotary workpiece-spindle axis. Such workpieces can be machined in an ordinary plunge grinding process by implementing the approach of RPM-Synchronous Non-Circular Grinding. Therefore, the workpiece and the grinding wheel rotational rates are in a fixed ratio. A non-circular grinding wheel is used to transfer its geometry onto the workpiece. The authors use a unique machine tool for basic research and control concept development for RPM-Synchronous Grinding (RSG). The machine was especially designed for this RSG technology. Highest revolution rates on the workpiece spindle are mandatory for its success. The grinding approach is performed in a two-step process. For roughing, a highly porous vitrified bonded grinding wheel with medium grain size is used. It ensures high specific material removal rates for producing the non-circular geometry on the workpiece efficiently. A control algorithm adapts this process step, which uses acquired data from a piezoelectric three-component force sensor fixed at the tailstock-side of the grinding machine. For finishing, a grinding wheel with fine grain size is suited. This process step is tuned by a digital process adaption strategy. Roughing and finishing are performed consecutively among the same clamping of the workpiece with two locally separated grinding spindles.

With the presented control and adaption concepts for RPM-Synchronous Grinding, a significant increase in surface quality on the workpiece is attained. The minimization of grinding wheel wear results concurrently. Especially the automotive industry shows big interest in RPM-Synchronous Non-Circular Grinding. This emerging trend in finishing machining opens up various fields of application.
Axiomatic Design of an Adjustable Lifting System for the Assembly of Booms of Telehandlers
Authors: Landi Luca , Sorgenti Agnese , Clerini Denny
Published: January 2018

This work describes the Axiomatic Design of a lifting system to be used during the assembly of various telescopic lift booms. The main function of the lifting system is to assist the workers during both the pre-assembly of the individual parts of a boom and also during the final assembly of a wide ranges of telescopic booms of telehandlers. Prior to the design of the lifting system the fundamental phase of data collection work is described in the paper. The company production process is analysed to detect the needs and design constraints impacting directly on the design stage. The preliminary design stage included: functional, ergonomic study of the lifting system and also considerations on the safety of operators during assembly.

The Axiomatic Design allows the designer to implement the Customer Needs into Functional Requirements and Design Parameters through a matrix description. So the product designer can recognize and properly transform Functional Requirements into Design Parameters during early stages of the design.

In the paper the development of this new lifting system is shown through Axiomatic Design method. The resulting modular lifting system and the principal results obtained will be described in terms of:

- reduction of assembly space on the “moving assembly chain” of the company,

- reduction of cycle time of the assembly of the boom using the new lifting system,

- improvement of ergonomic conditions of workers.

During the so called decoupling phase of Axiomatic Design, the Design Parameters of the lifting system are first determined and then hierarchically ordered. So the wasted time for typical trial and error process of advanced design stage is reduced because of this clear ordering.

The physical prototype of the new lifting system was already built and successfully used for the assembly on the industrial field.
Waste Heat Recovery by Organic Rankine Cycle (ORC) for Moist Exhaust Gases From Paper Industry
Authors: Lin Wamei , Nilsson Lars , Malutta Raffaele
Published: January 2018

Large potential exists in recovering waste heat from paper industry processes and machinery. If the overall energy efficiency would be increased, it could lead to significant fuel savings and greenhouse gas emission reduction. The organic Rankine cycle (ORC) system is a very strong candidate for converting low-grade waste heat into power. However, there is a lot of water vapor containing latent heat in the exhaust gases from the drying process in the paper industry. Thus, the aim of this research work is to increase the efficiency of the ORC system by recovering not only the sensible heat but also the latent heat from the exhaust gases in the paper drying process. In order to recover the latent heat from the moist exhaust gases, one idea of this article is to introduce a direct contact condensing unit into the ORC system. The performance of ORC system with the direct contact condensing unit was analyzed by using the CHEMCAD software. A case study was conducted based on data of the exhaust gases from a tissue production / drying machine. Latent heat will be recovered when the evaporating temperature of the ORC working fluid is lower than the dew point of the water vapor in the exhaust gases. The results showed that the available heat load was increased when the evaporating temperature was reduced. Furthermore, a performance comparison of the ORC systems with and without the direct contact condensing unit was carried out in the case study as well. The results showed that the ORC system with the direct contact condensing unit not only could recover latent heat from the water vapor in the exhaust gases but also could have a small size and small volume evaporator in the ORC system.
Large Deformation of Flexure Couplings for Robotic Arm Joints
Authors: Bailey Nicola Y. , Lusty Chris , Keogh Patrick S.
Published: January 2018

Conventional multi-body mechanisms used in robotics and automated machinery can have limited motion due to the bearing and transmission parts. Replacing a traditional bearing joint with a compact deformable structure (flexure coupling) can improve the performance envelope for a mechanism. A dynamic nonlinear mathematical model is derived for a mechanism comprising a flexure coupling, which can undergo large deformations, connected to a rigid link. Direct actuation of the mechanism is assumed in three directions and an open-loop control methodology is designed to regulate the actuation forces to achieve a prescribed path with precise and repeatable small scale motion. A mechanism containing a flexure coupling is examined and compared to that of an ideal hinge joint. The results show that a flexure coupling allows an increased range of motion for the mechanism compared to a hinge coupling and can have multiple paths in the x and y direction for a prescribed angle trajectory at the end of the mechanism.
Adapting Vertically Integrated Projects to University Team Competitions
Authors: Chipman Gregory D. , Fuller Thomas F.
Published: January 2018

Beginning in 2009 Vertically Integrated Projects (VIP) courses have been implemented at Georgia Tech. These VIP classes allow undergraduate students to receive academic credit for participating on teams that further faculty research efforts. The teams are: multidisciplinary, vertically-integrated, and long-term. Participation on these teams has been shown to help students gain understanding of project timelines, effective project communication, and other applicable real-world experience.

EcoCAR 3 is the latest in a series of Advanced Vehicle Technology Competitions (AVTCs) sponsored by the Department of Energy since 1988. At Georgia Tech, the EcoCAR 3 team has been structured using the VIP program to improve the all-around experience of faculty members and the graduate and undergraduate students. Based on Georgia Tech’s experience in the first three years in EcoCAR 3, we have learned lessons that we are implementing on our team to improve the educational experience of the students working on the project. One of these lessons is the value of strong undergraduate leadership on competition teams and in project based learning. The benefits have included a more evenly distributed workload, increased mentorship of new undergraduate students, and improved team capability to successfully meet deadlines while still educating undergraduate team members.
Filtration of Floating Particles by Collectors: Influence of the System Geometry on the Efficiency
Authors: Gregori Federico , Kapran Julia , Dressaire Emilie
Published: January 2018

Important industrial processes including oil extraction, mineral processing and wastewater treatment, rely on the separation of buoyant particles from a liquid phase. The capillary attraction between floating particles and fixed collectors can be leveraged to improve the efficiency of the separation process. The capture of an advected floating particle by a fixed cylindrical obstacle is due to direct interception and capillary attraction for sub-millimeter particles. The capillary attraction stems from the local deformation of the air/liquid interface. Previous work has established that floating particles placed on the surface of a still liquid bath, spontaneously move toward or away from one another depending on their surface properties. More recently, a numerical study has considered the competition between hydrodynamic and capillary interactions as floating particles are advected past a fixed cylinder. This seminal work revealed that capillary interactions can enhance the capture of particles at low flow velocity. Building on these results, we develop a numerical approach to study the interactions between advected particles and an array of obstacles. The results are obtained with the finite element modeling of the fluid flow in the channel, in presence of obstacles. Assuming that the particles do not alter the fluid flow, we solve the momentum conservation equation for each advected particle using the Basset Boussineq Oseen equation. If contact occurs, we assume that the particle is captured by the obstacle, thus neglecting inertial effects. We demonstrate that an array of obstacles can capture most of the particles traveling down the channel. First, we show that the efficiency of an array of obstacles, i.e. the fraction of particles captured depends on interfacial and hydrodynamic effects. For example, parameters such as the Reynolds number, capillary length, contact angle and collector size influence the trapping efficiency. Second we vary the geometry of the array and seek to minimize the amount of static material needed to get the maximum efficiency. These results provide guidelines for the design of efficient filters.
Comparison of Characteristics of Flow Around a Sphere With Trip Wire Using Different Turbulence Modeling Approaches
Authors: Vellakal Madhu , Torlak Muris , Koric Seid , Taha Ahmed
Published: January 2018

The flow characteristics of spherical bodies, arising in a variety of important engineering and environmental problems, range from laminar to turbulent flow. Turbulent flows are predominantly studied using the models based on Reynolds-averaged Navier-Stokes (RANS) equations. Especially, in case of flows around bluff bodies RANS models have limitations in capturing flow separation and other characteristic flow properties. Hence, the use of high-fidelity turbulent models is required to investigate the physics of these types of flow in detail. This study aims to compare and analyze the results of an incompressible turbulent flow around a sphere with additional geometric detail, like a trip wire, using different simulation techniques: Large Eddy Simulation (LES) and RANS. Modeling bodies with different characteristic geometric scales may require high-performance computing (HPC) resources due to the need to include accurate spatial and temporal resolution using unstructured mesh generation. This may be under circumstances additional criterion for decision which simulation approach is to be adopted.
Condensation of Low-Surface-Tension Fluids on Microstructured Surfaces at Low Temperature
Authors: Aili Abulimiti , Ge Qiaoyu , Zhang TieJun
Published: January 2018

Filmwise condensation of a low surface tension fluid (i.e. refrigerant) on microstructured aluminum surfaces is studied to investigate the effect of the structures on condensation heat transfer at low temperature. The hypothesis is that the structures may cause thinning of the condensate film at micro-scales, thus resulting in an enhancement of condensation heat transfer. However, the structures may also decrease the mobility of the condensate near the surface due to increased friction, thus potentially leading to performance deterioration. The aim of this work is to investigate which of the two counteracting mechanisms dominate during filmwise condensation. Condensation experiments are carried out in a low-temperature vacuum chamber. Compared with the Nusselt model of condensation, the microstructured surfaces, either coated or uncoated, show similar performance, with potentially slight enhancement at low subcooling degree and slight deterioration at high subcooling degree. When the microstructured and silane-coated surface is infused with a non-volatile and very low-surface-tension lubricant oil, the lubricant is displaced by the condensate and there is almost no change in the condensation performance. Our results show that, unlike the case of dropwise condensation of high-surface tension fluids, microstructured and coated surfaces with/without infusing oil is not exciting to enhanced filmwise condensation of low-surface-tension fluids.
Utilizing a Numerical Simulation to Model a Step Function Response for 420 Stainless Steel Powder Laser Cladding
Authors: Nazemi Navid , Urbanic Ruth Jill , Saqib Syed
Published: January 2018

To develop realistic process planning simulation tools and build strategies, an understanding of realistic transient conditions needs to be explored for multiple overlapping beads and 3D build ups. In the past, most of the research has focused on optimization strategies for a process configuration, typically for a single-track bead in steady state conditions. Changes in the bead geometry are inherent when depositing material; consequently, understanding dynamic, time varying heating and solidification conditions for multiple bead scenarios needs to be investigated. It is important to understand the system characteristics and its influence on the all the bead geometry parameters (not just the width) and the resultant hardness. Initially, a set of physical laser cladding experiments have been performed for single and multiple bead scenarios using 420 stainless steel powder being deposited onto mild steel plate with step variations being applied for the process power. For this research, complementary simulation models are developed, and the effects of the transient conditions on the bead hardness for several scenarios are investigated for four process power input step-functions using an imposed thermal cycling simulation approach. It is observed that the hardness values change from higher to lower values between the first and third beads, and for all scenarios, the hardness converges to a uniform value. When comparing geometry and hardness results, it can be seen that the geometry has more oscillations than the hardness. More research in this area is essential to develop robust real-time control solutions that encompass functional requirements such as hardness as well as the bead geometry.
Fuel Economy, Emission and Life Cycle Costing Generation From Database
Authors: Rabbi Ehtesam , Yang Cai Xia
Published: January 2018

The selection process and procurement of right transit bus with fuel and powertrain technology is vital for any cost-effective transit service. There are cities in which conventional diesel fueled bus is used for transit service. It is not always viable to replace the whole or part of the fleet with a vehicle with a different powertrain. Every city are unique in its road type, road grade, service routes, meteorological aspects and traffic population. Since, each of the powertrain technology offers a different combination of advantages and disadvantages, we need to study and analysis each drivetrain technology to find out the best match for our city. There is a variation in transit bus types that are suitable for distinct types of cities, services, and operations. Fuel consumption is directly related to the bus size, engine technology and powertrain. Evaluating fuel consumption correctly, predicting detailed emission for the greenhouse gases and analyzing life cycle costing could be a daunting task and often needs expensive on-board equipment and intricate simulation testing. Lacking this kind of amenities makes it impossible for transit service on a county scale and project level research. In this study, a local database of transit service generated from the well documented database to provide a detailed analysis of fuel consumption, emission and life cycle costing. The integral part of evaluating fuel consumption accurately is to compare test data over a relevant drive cycle. This research also discusses drive cycle and how to select from standard drive cycle for urban city transit network.
Evaluating Material Property Variations in Components With Difficult Geometries
Authors: Amine Tarak , Newkirk Joseph W. , O’Malley Ronald J.
Published: January 2018

All manufacturing methods produce components which have some degree of inhomogeneous properties. Part properties may vary with location in most fabrication methods including additive manufacturing, casting, forging, welding, and surface modifications. Standard tensile test specimens cannot provide a good map of the properties of the material, except for only the largest of components or simplest of geometries. For example, simple curved shapes, such as pipes cannot be reliably evaluated by straight tensile specimens unless the pipe diameter is large enough to have a sufficiently low curvature from which flat specimens can be machined.

This paper will look at part property variations in various components made by different fabrication methods, which include selective laser melting, press and sinter powder metallurgy, rolling and casting. Subsize tensile specimens developed at the Missouri University of Science and Technology have been used to map out material properties with location. This method of mapping out properties provides new information which could be valuable to quality control, process control, and design of components.
Numerical Analysis on the Influence of Taper Junction Corrosion Profile With Emphasis on Ti-Alloy Modular Hip Arthroplasty
Authors: Novotny Adam , Paliwal Manish
Published: January 2018

Modular designs give orthopaedic surgeons a greater flexibility to custom fit the implant to the patients bone while performing total hip arthroplasty. Titanium alloy (Ti6Al4V (ASTM F-136)) is typically used for modular hip implant stems. This highly corrosion resistant alloy forms passive surface oxide films spontaneously. However, with modular designs, micro-motion may occur at the taper junctions during mechanical loading. Crevices between the taper junctions may allow the body fluids to enter and remain stagnant. These conditions make the modular tapers susceptible to fatigue and mechanically assisted crevice corrosion. The in vivo degradation of metal alloy implants compromises the structural integrity. The influence of stress corrosion induced pits of a titanium-alloy modular implant in cement-less total hip arthroplasty was numerically investigated. The effect of pit geometry parameters — cylindrical, conical, and hemispherical dimple are compared and discussed in terms of taper performance.
Modeling of TCP Muscles for Understanding Actuation Behavior
Authors: Karami Farzad , Tadesse Yonas
Published: January 2018

Twisted and Coiled Polymers (TCP) muscles are actuators that generate force and linear displacement in response to thermal stimuli. Their length changes significantly by heating due to a high negative coefficient of thermal expansion (CTE). A mathematical model for predicting the behavior of TCP muscles is essential for exploiting maximum advantage from these actuators and also controlling them. In this work, a simple, practical, and accurate model for predicting the displacement of TCP muscles, as a function of input electrical actuation and load, is derived. The problem is broken down into two, i.e. modeling of the thermal and thermo-elastic part. For the first part, a differential equation with changing electrical resistance term is derived. In the next step, by using a temperature-dependent modulus of elasticity and CTE as well as taking the geometry of muscles into account, an expression for displacement as a function of temperature and load is proposed. Experimental actuation data of a TCP muscle is used for verifying the model and investigating its accuracy. The thermal part shows a good agreement between the simulation and experimental result. The displacement part also has a good accuracy for medium and high actuation currents but there is a mismatch in very high current magnitudes. The cause of the discrepancy is explained and recommendations are made for the best performance of TCP muscles.
Heat Flux Characteristics of Asymmetrically Heated and Cooled Thermal Stimuli
Authors: Hojatmadani Mehdi , Hardy Matthew , Manasrah Ahmad , Guldiken Rasim , Reed Kyle
Published: January 2018

The human thermal response system can be manipulated by the proper combination of applied hot and cold stimuli. Previous research has shown that a sensation of constant cooling can be perceived through the application of certain patterns on the skin. Here we focus on (1) exploring the heat flux characteristics of the thermal display through computer simulations, (2) testing a hypothesis about the relationship between thermal sensation and heat flux, and (3) examining modifications of the thermal display patterns to intensify thermal sensations. To characterize the heat flux patterns of the thermal display, finite element simulations were performed using ANSYS. Simulations were done in two parts: the first examined a small subregion between heating and cooling stimuli, and the second was a larger scale examination of the heat flux profile of the thermal display. It was observed that the heat flux profiles for all thermal patterns were approximately identical. A linear relationship is derived between simulation and experimental results. This relationship was then used to determine the theoretical thermal sensations to determine which are best suited for future physical experimentation on humans.
Development and Validation of a Finite Element Lower Limb Model for Elderly Females
Authors: Khandelwal Prashant , Kalra Anil , Jiang Binhui , Hammad Anand , Jin Xin , Yang King H.
Published: January 2018

Physical surrogates and numerical models have been used to investigate the lower limb injury responses in blunt trauma related to occupant and pedestrian impacts during crash events. To date, automotive crash dummies used for studying the lower limb kinematics and injury responses in car crashes are designed to represent mid-age adults. But due to increase in fragility and frailty with age, the injury risk of the lower limb of elderly females is greater compared to younger adults. Thus, safety designs should expand for protecting elderly females in lower limb impacts.

The current study focuses on developing a lower limb finite element model for elderly females with accurate anthropometry and anatomical details. The model was further validated against segmental and whole-body level experimental data of lower limb impact during pedestrian, frontal, and side impact loading. The validated model will be further integrated into the whole-body model to study injury mechanisms and safety designs for this vulnerable population of elderly females.
CFD Multiphysics Modeling and Performance Evaluation of PEM Fuel Cells
Authors: Fontalvo Victor , Illera Danny , Gómez Humberto , Sanjuan Marco
Published: January 2018

Computational Fluid Dynamics (CFD) models allows the three-dimensional simulation of the complex electrochemical, fluid dynamics, and thermodynamic phenomena related to the temperature and pressure distribution in the channels and the porous media than occurs inside the fuel. This work presents a CFD Multiphysics simulation of a PEM Fuel Cell under different operational conditions in their inlet streams. The simulation was done by using COMSOL Multiphysics® software, and it takes into account the mass transfer of gases in the channels, the porous media and the electrochemistry from reactions in a 5 cm2 active area. From the electrochemical perspective, the relationship between the charge transfer and the overpotentials are taken into account by kinetic expressions. In addition, the ohm’s law is applied in conjunction with the charge transfer to describe the conduction of current in the electrodes and electrolytes. Gas diffusion layers (GDL) along with the catalyst layers are modeled as porous media restricting the electrochemical reaction. As the result of different simulation scenarios representing different operational conditions, the characteristic Polarization Curve of the fuel cell, the dependence between the voltage in the cell, and the demanded current by the load are obtained. A reduction in the electrical potential was evidenced due to the reaction activation potential, the ohmic losses due to the electrical resistance of the materials and the concentration losses as a result of deficiencies in the diffusion of the reactants through the porous medium. Currents distributions and water content are analyzed in order to understand the role of temperature, load, and humidity over the fuel cell performance.
Correlation of Mixing Efficiency and Entropy Generation Rate in a Square Cross Section Tee Junction Micromixer
Authors: Gillispie Aric M. , Lemley Evan C.
Published: January 2018

The potential applications of micromixers continues to expand in the bio-sciences area. In particular, passive micromixers that may be used as part of point-of-care (POC) diagnostic testing devices are becoming commonplace and have application in developed, developing, and relatively undeveloped locales. Characterizing and improving mixing efficiency in these devices is an ongoing research effort. Micromixers are used in some lab-on-chip (LOC) devices where it is often necessary to combine two or more fluids into a mixed solution for testing or delivery. The simplest micromixer incorporates a tee junction to combine two fluid species in anti-parallel branches, with the mixed fluid leaving in a branch perpendicular to the incoming branches. Micromixers rely on two modes of mixing: chaotic advection and molecular diffusion. In micro-mixers flow is typically laminar, making chaotic advection occur only via induced secondary flows. Hence, micromixers, unless carefully designed, rely almost exclusively on molecular diffusion of fluid species. A well designed micromixer should exhibit significant chaotic advection; which is also a sign of large strain rates and large entropy generation rates.

This paper describes the development of an analytical relationship for the entropy generation rate and the mixing efficiency as function of the outgoing branch Reynolds number. Though there has been extensive research on tee junctions, entropy generation, and the mixing efficiencies of a wide variety of micromixers, a functional relationship for the mixing efficiency and the entropy generation rate has not been established. We hypothesize a positive correlation between the mixing index and the entropy generation rate. The worked described here establishes a method and provides the results for such a relationship.

A basic tee junction with square cross sections has been analyzed using computational fluid dynamics to determine the entropy generation rate and outgoing mixing efficiencies for Reynolds numbers ranging from 25–75. The mixing efficiency is determined at a location in the outgoing branch where the effects of molecular diffusive mixing is minimized and chaotic advective mixing is the focus. The entropy generation rate has been determined for the indicated range of Reynolds number and decomposed into its viscous and diffusive entropy terms. The functional relationships that have been developed are applicable for micromixer design and serve as a reference for more complex passive micromixer designs.
A Multi-Scale Model for Bending Stiffness of CNT Strands in CNT Fibers
Authors: Imani Azad Ali , Dargazany Roozbeh , Mirzaeifar Reza , Mall Shankar
Published: January 2018

Carbon Nanotube (CNT) fibers are 3D-woven hierarchical assemblies of CNTs which show excellent mechanical and electrical properties. There is a tremendous loss of mechanical performance in the scale transition from individual CNT to fibers, over which we have limited understanding. Our knowledge of load transfer across different length scales is scarce and inconclusive. Here, the objective is to explore the load transfer mechanism (LTM) of CNT fibers, by identifying the contribution of defects on mechanical performance of fibers at various length scales. A micromechanical-based constitutive model is developed to describe bending-tensile properties of strands as an assembly of twisted yarns. The model associates the strand response to two states of deformation referred to as stick and slip states. Several inelastic features were considered in calculation of the response of strands, such as local jamming, evolution of the void area between yarns, and friction. The model is validated against different sets of experiments.
Striation-based source depth estimation with a vertical line array in the deep ocean
Authors: Yang Kunde , Xu Liya , Yang Qiulong , Duan Rui
Published: January 2018

A striation-based method with a vertical line array is proposed for source depth estimation. Broadband striation structures of direct and surface-reflected arrivals after propagating to receivers near the ocean bottom are applied. A tracking algorithm for the striation structures is proposed based on the extended Kalman filter. A cost function for source depth estimation is presented by matching the traces of the measured striations with a library of model-based traces under different source depths. The method is demonstrated on array data collected during an acoustic research experiment in the South China Sea in 2016.
Low-threshold parametric oscillation in organically modified microcavities
Authors: Shen Xiaoqin , Beltran Rigoberto Castro , Diep Vinh M. , Soltani Soheil , Armani Andrea M.
Published: January 2018

Combining nanometer-thick coatings of organic small molecules with optical resonators generates sub-microwatt frequency combs.
Using
para
hydrogen to hyperpolarize amines, amides, carboxylic acids, alcohols, phosphates, and carbonates
Authors: Iali Wissam , Rayner Peter J. , Duckett Simon B.
Published: January 2018

Para
hydrogen is used to give efficient NMR detection of array of amines, amides, alcohols, carboxylates, carbonates, and phosphates.
Type I interferons instigate fetal demise after Zika virus infection
Authors: Yockey Laura J. , Jurado Kellie A. , Arora Nitin , Millet Alon , Rakib Tasfia , Milano Kristin M. , Hastings Andrew K. , Fikrig Erol , Kong Yong , Horvath Tamas L. , Weatherbee Scott , Kliman Harvey J. , Coyne Carolyn B. , Iwasaki Akiko
Published: January 2018

After Zika virus infection, fetal type I interferon signaling is responsible for abnormal placental development and fetal resorption.
Antiviral immunity backfires: Pathogenic effects of type I interferon signaling in fetal development
Authors: Casazza Rebecca L. , Lazear Helen M.
Published: January 2018

Interferon-α/β signaling is pathogenic in a mouse model of congenital Zika virus infection. See related research article by

Yockey
et al.
Functional variants in the
LRRK2
gene confer shared effects on risk for Crohn’s disease and Parkinson’s disease
Authors: Hui Ken Y. , Fernandez-Hernandez Heriberto , Hu Jianzhong , Schaffner Adam , Pankratz Nathan , Hsu Nai-Yun , Chuang Ling-Shiang , Carmi Shai , Villaverde Nicole , Li Xianting , Rivas Manual , Levine Adam P. , Bao Xiuliang , Labrias Philippe R. , Haritunians Talin , Ruane Darren , Gettler Kyle , Chen Ernie , Li Dalin , Schiff Elena R. , Pontikos Nikolas , Barzilai Nir , Brant Steven R. , Bressman Susan , Cheifetz Adam S. , Clark Lorraine N. , Daly Mark J. , Desnick Robert J. , Duerr Richard H. , Katz Seymour , Lencz Todd , Myers Richard H. , Ostrer Harry , Ozelius Laurie , Payami Haydeh , Peter Yakov , Rioux John D. , Segal Anthony W. , Scott William K. , Silverberg Mark S. , Vance Jeffery M. , Ubarretxena-Belandia Iban , Foroud Tatiana , Atzmon Gil , Pe’er Itsik , Ioannou Yiannis , McGovern Dermot P. B. , Yue Zhenyu , Schadt Eric E. , Cho Judy H. , Peter Inga
Published: January 2018

Crohn’s disease (CD)–associated variants in the
LRRK2
gene for risk (N2081D) and for protection (N551K) mediate shared effects in CD and Parkinson’s disease.
The antimicrobial peptide SAAP-148 combats drug-resistant bacteria and biofilms
Authors: de Breij Anna , Riool Martijn , Cordfunke Robert A. , Malanovic Nermina , de Boer Leonie , Koning Roman I. , Ravensbergen Elisabeth , Franken Marnix , van der Heijde Tobias , Boekema Bouke K. , Kwakman Paulus H. S. , Kamp Niels , El Ghalbzouri Abdelouahab , Lohner Karl , Zaat Sebastian A. J. , Drijfhout Jan W. , Nibbering Peter H.
Published: January 2018

Infections refractory to conventional antibiotics may be targeted by the antimicrobial peptide SAAP-148.
MgtE Homolog FicI Acts as a Secondary Ferrous Iron Importer in Shewanella oneidensis Strain MR-1
Authors: Bennett Brittany D. , Redford Kaitlyn E. , Gralnick Jeffrey A.
Published: January 2018

The transport of metals into and out of cells is necessary for the maintenance of appropriate intracellular concentrations. Metals are needed for incorporation into metalloproteins but become toxic at higher concentrations. Many metal transport proteins have been discovered in bacteria, including the Mg
2+
transporter E (MgtE) family of passive Mg
2+
/Co
2+
cation-selective channels. Low sequence identity exists between members of the MgtE family, indicating that substrate specificity may differ among MgtE transporters. Under anoxic conditions, dissimilatory metal-reducing bacteria, such as
Shewanella
and
Geobacter
species, are exposed to high levels of soluble metals, including Fe
2+
and Mn
2+
. Here we characterize SO_3966, which encodes an MgtE homolog in
Shewanella oneidensis
that we name FicI (
f
errous
i
ron and
c
obalt
i
mporter) based on its role in maintaining metal homeostasis. A SO_3966 deletion mutant exhibits enhanced growth over that of the wild type under conditions with high Fe
2+
or Co
2+
concentrations but exhibits wild-type Mg
2+
transport and retention phenotypes. Conversely, deletion of
feoB
, which encodes an energy-dependent Fe
2+
importer, causes a growth defect under conditions of low Fe
2+
concentrations but not high Fe
2+
concentrations. We propose that FicI represents a secondary, less energy-dependent mechanism for iron uptake by
S. oneidensis
under high Fe
2+
concentrations.

IMPORTANCE
Shewanella oneidensis
MR-1 is a target of microbial engineering for potential uses in biotechnology and the bioremediation of heavy-metal-contaminated environments. A full understanding of the ways in which
S. oneidensis
interacts with metals, including the means by which it transports metal ions, is important for optimal genetic engineering of this and other organisms for biotechnology purposes such as biosorption. The MgtE family of metal importers has been described previously as Mg
2+
and Co
2+
transporters. This work broadens that designation with the discovery of an MgtE homolog in
S. oneidensis
that imports Fe
2+
but not Mg
2+
. The research presented here also expands our knowledge of the means by which microorganisms have adapted to take up essential nutrients such as iron under various conditions.
A Brief History of
Shigella
Authors: Lampel Keith A. , Formal† Samuel B. , Maurelli Anthony T.
Published: January 2018

The history of
Shigella
, the causative agent of bacillary dysentery, is a long and fascinating one. This brief historical account starts with descriptions of the disease and its impact on human health from ancient time to the present. Our story of the bacterium starts just before the identification of the dysentery bacillus by Kiyoshi Shiga in 1898 and follows the scientific discoveries and principal scientists who contributed to the elucidation of
Shigella
pathogenesis in the first 100 years. Over the past century,
Shigella
has proved to be an outstanding model of an invasive bacterial pathogen and has served as a paradigm for the study of other bacterial pathogens. In addition to invasion of epithelial cells, some of those shared virulence traits include toxin production, multiple-antibiotic resistance, virulence genes encoded on plasmids and bacteriophages, global regulation of virulence genes, pathogenicity islands, intracellular motility, remodeling of host cytoskeleton, inflammation/polymorphonuclear leukocyte signaling, apoptosis induction/inhibition, and “black holes” and antivirulence genes. While there is still much to learn from studying
Shigella
pathogenesis, what we have learned so far has also contributed greatly to our broader understanding of bacterial pathogenesis.
Whole-Genome Draft Sequences of Nine Asymptomatic
Escherichia coli
Bacteriuria Isolates from Diabetic Patients
Authors: Stork Christoph , Kovács Beáta , Trost Eva , Kovács Tamás , Schneider György , Rózsai Barnabás , Kerényi Monika , Emődy Levente , Dobrindt Ulrich
Published: January 2018

Escherichia coli
can colonize the urinary bladder without causing a disease response in the host. This asymptomatic bacteriuria (ABU) can protect against recurrent symptomatic urinary tract infection by virulent bacteria. Here, we report the whole-genome sequences of nine
E. coli
ABU isolates from diabetic patients.
Complete Genome Sequence of
Thermoanaerobacterium
sp. Strain RBIITD, a Butyrate- and Butanol-Producing Thermophile
Authors: Biswas Ranjita , Huntemann Marcel , Clum Alicia , Pillay Manoj , Palaniappan Krishnaveni , Varghese Neha , Mikhailova Natalia , Stamatis Dimitrios , Reddy T. B. K. , Daum Chris , Shapiro Nicole , Ivanova Natalia , Kyrpides Nikos C. , Woyke Tanja , Guss Adam M.
Published: January 2018

Thermoanaerobacterium
sp. strain RBIITD was isolated from contaminated rich growth medium at 55°C in an anaerobic chamber. It primarily produces butyrate as a fermentation product from plant biomass-derived sugars. The whole-genome sequence of the strain is 3.4 Mbp, with 3,444 genes and 32.48% GC content.
Experimental Epidemiology of Antibiotic Resistance: Looking for an Appropriate Animal Model System
Authors: Llop Pablo , Latorre* Amparo , Moya* Andrés
Published: January 2018

Antibiotic resistance is recognized as one of the major challenges in public health. The global spread of antibiotic resistance is the consequence of a constant flow of information across multi-hierarchical interactions, involving cellular (clones), subcellular (resistance genes located in plasmids, transposons, and integrons), and supracellular (clonal complexes, genetic exchange communities, and microbiotic ensembles) levels. In order to study such multilevel complexity, we propose to establish an experimental epidemiology model for the transmission of antibiotic resistance with the cockroach
Blatella germanica
. This paper reports the results of five types of preliminary experiments with
B. germanica
populations that allow us to conclude that this animal is an appropriate model for experimental epidemiology: (i) the composition, transmission, and acquisition of gut microbiota and endosymbionts; (ii) the effect of different diets on gut microbiota; (iii) the effect of antibiotics on host fitness; (iv) the evaluation of the presence of antibiotic resistance genes in natural- and lab-reared populations; and (v) the preparation of plasmids harboring specific antibiotic resistance genes. The basic idea is to have populations with higher and lower antibiotic exposure, simulating the hospital and the community, respectively, and with a certain migration rate of insects between populations. In parallel, we present a computational model based on P-membrane computing that will mimic the experimental system of antibiotic resistance transmission. The proposal serves as a proof of concept for the development of more-complex population dynamics of antibiotic resistance transmission that are of interest in public health, which can help us evaluate procedures and design appropriate interventions in epidemiology.
Migrant perinatal depression study: a prospective cohort study of perinatal depression on the Thai-Myanmar border
Authors: Fellmeth Gracia , Plugge Emma H , Carrara Verena , Fazel Mina , Oo May May , Phichitphadungtham Yuwapha , Pimanpanarak Mupawjay , Wai Naw Kerry , Mu Oh , Charunwatthana Prakaykaew , Nosten François , Fitzpatrick Raymond , Mcgready Rose
Published: January 2018

Purpose

Perinatal depression is a significant contributor to maternal morbidity. Migrant women in resource-poor settings may be at increased risk, yet little research has been conducted in low-income and middle-income settings. This prospective cohort study of migrant women on the Thai-Myanmar border aims to establish prevalence of perinatal depression, identify risk factors for perinatal depression and examine associations with infant outcomes.

Participants

Participating women are labour migrants and refugees living on the Thai-Myanmar border. A total of 568 women were recruited in their first trimester of pregnancy and are being followed up to 1-year postpartum.

Findings to date

At baseline, women in our study had a median age of 25 years, the predominant ethnicity was Sgaw Karen (48.9%), agriculture was the main employment sector (39.2%) and educational attainment was low with a median of 4 years of education. In the first trimester of pregnancy, a quarter (25.8%; 95% CI 22.3 to 29.5) of all women were depressed as diagnosed by theStructured Clinical Interview for the Diagnosis of DSM-IV Disorders.

Future plans

Follow-up is ongoing and expected to continue until January 2018. The prevalence of depression at later stages of pregnancy and during the first postpartum year will be identified, and associations between depression status and demographic, social, migration-related, medical, obstetric and infant factors will be quantified.

Trial registration number

NCT02790905.
Seasonal variation in home blood pressure: findings from nationwide web-based monitoring in Japan
Authors: Iwahori Toshiyuki , Miura Katsuyuki , Obayashi Keiichi , Ohkubo Takayoshi , Nakajima Hiroshi , Shiga Toshikazu , Ueshima Hirotsugu
Published: January 2018

Objectives

Our aim was to assess seasonal variation in home blood pressure (BP) among free-living nationwide participants using home BP values accumulated from a web-based healthcare platform established in Japan.

Settings

An observational study. OMRON Healthcare Co., Ltd. has been developing web-based personal healthcare record systems in Japan since November 2010; over two million voluntary participants had joined this platform in September 2015. Nationwide home BP measurements made by oscillometric-type electronic sphygmomanometers from over 110 000 voluntary participants have been transmitted to the system from devices.

Participants

Seasonal variation in home BP was evaluated among 64 536 (51 335 men, 13 201 women; mean age 52.9 years) free-living nationwide users for whom data were automatically and simultaneously transmitted to the system from devices.

Primary outcome measures

Mean monthly and weekly home BP.

Results

In multiple regression analysis, the relationship between BP and temperature was a significant inverse association, independent of age, gender and geological locations. Highest and lowest BP was observed in December and July, respectively. Substantial seasonal differences in the mean values of morning and evening home systolic BP between summer and winter were 6.2 mmHg and 5.5 mmHg in men, and 7.3 mmHg and 6.5 mmHg in women. Seasonal variation was a little greater in older (7.3 mmHg in men, 8.7 mmHg in women) than in younger individuals (5.8 mmHg in men, 6.5 mmHg in women). BP from February to July was approximately 1.5 mmHg lower than the value from August to December.

Conclusions

A web-based healthcare platform has enabled easier monitoring of population-wide BP. Tighter BP control is necessary in winter than in summer, and especially in a colder climate toward winter than toward summer. New technologies using web-based self-monitoring systems for health-related indexes are expected to initiate a new phase of cardiovascular disease prevention and public health promotion.
Observational study of the differential impact of time-varying depressive symptoms on all-cause and cause-specific mortality by health status in community-dwelling adults: the REGARDS study
Authors: Moise Nathalie , Khodneva Yulia , Jannat-Khah Deanna Pereira , Richman Joshua , Davidson Karina W , Kronish Ian M , Shaffer Jonathan , Safford Monika M
Published: January 2018

Objective

To assess the association between time-varying depressive symptoms with all-cause and cause-specific mortality.

Design

The REGARDS (Reasons for Geographic and Racial Differences in Stroke) is a national, population-based longitudinal study conducted from 2003 to 2007.

Setting

General continental US communities.

Participants

29 491 black and white US adults ≥45 years randomly sampled within race–sex–geographical strata.

Exposure

Elevated depressive symptoms (Centre for Epidemiologic Studies Depression (CES-D) 4≥4) measured at baseline and on average 5 and 7 years later.

Main outcome measures

Cox proportional hazard regression models assessed cancer, non-cardiovascular (cardiovascular disease (CVD)), CVD and all-cause mortality.

Results

The average age was 64.9 years; 55% were women; 41% black; 11.0% had elevated depressive symptoms; 54% had poor, fair or good health. Time-varying depressive symptoms were significantly associated with non-CVD (adjusted HR (aHR)=1.29, 95% CI 1.16 to 1.44) and all-cause (aHR=1.24, 95% CI 1.14 to 1.39), but not cancer (aHR=1.15, 95% CI 0.96 to 1.38) or CVD (aHR=1.13, 95% CI 0.98 to 1.32) death adjusting for demographics, chronic clinical diseases, behavioural risk factors and physiological factors. Depressive symptoms were related to all-cause (aHR=1.48, 95% CI 1.27 to 1.78), CVD (aHR=1.37, 95% CI 0.99 to 1.91), non-CVD (aHR=1.54, 95% CI 1.24 to 1.92) and cancer (aHR=1.36, 95% CI 0.97 to 1.91) death in those who reported excellent or very good health. The analyses of the association between one measure of baseline depressive symptoms and mortality analyses yielded similar results.

Conclusions

Time-varying depressive symptoms confer an increased risk for all-cause mortality, CVD, non-CVD death and cancer death, particularly in those with excellent or very good health. These findings may have implications for timely treatment, regardless of health status.