bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite Element Analysis of Electroactive and Magnetoactive Coupled Behaviors in Multi-Field Origami Structures
Authors: Zhang Wei , Erol Anil , Ahmed Saad , Masters Sarah , von Lockette Paris , Ounaies Zoubeida , Frecker Mary
Published: November 2017

Active origami designs, which incorporate smart materials such as electroactive polymers (EAPs) and magnetoactive elastomers (MAEs) into mechanical structures, have shown good promise in engineering applications. In this study, finite element analysis (FEA) models are developed using COMSOL Multiphysics software for two configurations that incorporate a combination of active and passive material layers, namely: 1) a single-notch unimorph folding configuration actuated using only external electric field and 2) a bimorph configuration which is actuated using both electric and magnetic (i.e. multifield) stimuli. Constitutive relations are developed for both electrostrictive and magnetoactive materials to model the coupled behaviors directly. Shell elements are adopted for their capacity of modeling thin films, reduction of computational cost and ability to model the intrinsic coupled behaviors in the active materials under consideration. A microstructure-based constitutive model for electromechanical coupling is introduced to capture the nonlinearity of the EAP’s relaxor ferroelectric response; the electrostrictive coefficients are then used as input in the constitutive modeling of the coupled behavior. The magnetization of the MAE is measured by experiment and then used to calculate magnetic torque under specified external magnetic field. The objective of the study is to verify the effectiveness of the constitutive models to simulate multi-field coupled behaviors of the active origami configurations. Through quantitative comparisons, simulation results show good agreement with experimental data, which is a good validation of the shell models. By investigating the impact of material selection, location, and geometric parameters, FEA can be used in design, reducing trial-and-error iterations in experiments.
Design of Smart Barb of Honeybee-Inspired Surgery Needle
Authors: Khodaei Seyedvahid , Sahlabadi Mohammad , Hutapea Parsaoran
Published: November 2017

Needles are among the most common used instruments in surgery by medical professionals either for diagnosing the disease such as biopsy or for medical intervention such as drug delivery. Generally, needles are assumed to be minimally invasive, however it is desirable to decrease the insertion and pulling out force in order to prevent tissue damages. The hypothesis is that reducing the resistance forces caused by needle-tissue interaction leads to less tissue damage and less pain. Bioinspired needles mimicking insect stingers have been designed to reduce this resistance force and this design could provide to a more sophisticated steering of needle. Although our earlier study on honeybee-mimicking needle has shown the reduction of insertion force by having barbs on the needle body, the pull-out force is a big concern in particular during the extraction of the needle. A special mechanism to control the barbs at the end of the insertion procedure is designed. In this study, we investigated the use of SMA to control the barb functions so that it will reduce the pull-out force of the bioinspired needles. In this work, smart barb design is proposed. Circular barbs are divided to two symmetric parts connected by a ring around the central axis of the needle and the rings are connected to form the base part of its structure. Barbs are designed to have parallel faces with a desired angle through the insertion mechanism and are connected with a SMA wire at their bottom that is connected to the rear and front part of the needle. After insertion, actuating the SMA wires force the barbs to rotate around the rings due to the torque provided by wire shrinkage. As a result, barbs have now the same angle along the movement of needle for pulling out as they have for insertion mechanism.
Active-Passive Damping Characteristics of Extension and Shear Mode Piezoelectric Fiber Nano-Reinforced Composite (PFNRC)
Authors: Kavathia Kepin , Settipalli Manoj , Raja Samikkannu
Published: November 2017

This paper presents a simulation-based study to investigate the damping properties of a novel piezocomposite, consisting of piezoelectric fiber and epoxy reinforced with randomly orientated double walled carbon nanotubes (DWCNT), termed as piezoelectric fiber nano reinforced composite (PFNRC). Authors have observed that the past research dealt with the effect of aligned single walled carbon nanotubes (CNT) on active damping of piezoelectric composite in extension mode (e13 and e33). It is known from the past research that DWCNT inclusions improve the passive damping of a composite. Therefore, the authors use DWCNT inclusions to study the active-passive damping of the piezoelectric composite, in this article. The random orientation of the DWCNT is considered to replicate the physical composite as it known that aligning CNTs in a single direction is not feasible due to fabrication constraints. A multistep homogenization method involving Method of Cells (MOC) is employed to obtain effective properties of PFNRC. A modified 3D-MOC is used to obtain the effective properties of epoxy matrix with DWCNT inclusions (DWCNT-epoxy), considering the effect of nano particle agglomeration. A 2D-MOC is then implemented with long fiber PZT as the active material and DWCNT-epoxy as the matrix. This procedure is followed for computing the effective material properties of extension (e33) as well as shear (e15) mode of PFNRC, when DWCNT inclusions are added into the epoxy matrix at different weight percentages. The constitutive equations are derived with the help of Maple and simulated in MATLAB. These results are used to compare the active-passive damping performance of the composites using a single degree of freedom damping model, employing Newmark’s numerical integration method. The active damping performance of the composites is evaluated by varying the displacement and velocity gains in a negative feedback system. The main focus of the study is to find the most efficient operating mode of the proposed composite for damping of structural vibrations.
Trade Space Exploration of a Magnetically Actuated Miura-Ori Structure
Authors: Cowan Brett , von Lockette Paris
Published: November 2017

Origami folding patterns are finding use in novel applications where actual device response depends on current, possibly intermediate, shapes on the path toward the final target shape. This works investigates one origami pattern, developing metrics for performance that incorporate traditional shape approximation and actuator efficiency, while adding proxy measures of adherence to the target folding path. Magnetically actuated Miura-Ori structures were develop using an initially heuristic strategy involving experiment, observation, and computation before being studied using trade space optimization/visualization. Constructed from PDMS substrates, notched to promote the crease pattern, and neodymium magnets, four initial configurations were chosen based on heuristic arguments that (1) maximized the amount of magnetic torque applied to the creases and (2) reduced the number of magnets needed to affect all creases in the pattern. Experiments were conducted, and calculations performed, on prototypes from each configuration to determine their degree of closure for a fixed maximum field strength, their ability to follow the ideal Miura-Ori folding pattern, and the amount of work theoretically performed by each magnet on each crease. Each configuration was further optimized theoretically using the Army Trade Space Visualization (ATSV) software. A final prototype was constructed following the weighted sum scoring of the four now optimized configurations. Somewhat surprisingly, trade space optimization showed that the configuration with the highest number of actuators was theoretically the least effective per magnet at delivering torque to each crease. Unsurprisingly, optimization was successful at increasing the amount of work theoretically apportioned to each crease. Overall, though the winning configuration experimentally outperformed its initial, non-optimal counterparts, results showed that the choice of optimum configuration was heavily dependent on the weighting factors within the objective function. These results highlight the ability of the Miura-Ori to be actuated with external magnetic stimuli, the effectiveness of a hybrid heuristic - trade space design approach that focuses on the actuation mechanism, and the need to address path-dependent metrics in assessing performance in origami folding structures.
A Sensor Fusion Based Pan-Tilt Platform for Activity Tracking and Fall Detection
Authors: Chen Zhangjie , Liu Hanwei , Wang Yuqiao , Wang Ya
Published: November 2017

This paper presents a pan-tilt sensor fusion platform for activity tracking and fall-detection which can work as a reliable surveillance system with long-term care function. A low cost thermal array sensor and a distance sensor are integrated together as the sensor module. The sensor module is installed on a pan-tilt orienting mechanism with two rotation degrees of freedom to increase the field of view while reducing the number of sensors used on-board. The performance of the sensor test platform is analyzed. The location of the indoor object as well as its size can be estimated based on a novel sensor fusion algorithm. The support vector machine (SVM) based machine learning algorithm is applied for fall detection. The preliminary experiment result shows a 95% accuracy to identify falling action from similar normal indoor activity such as sitting and picking up stuff.
Exploitation of Adaptive Trailing Edge Architectures to Small Aircraft
Authors: Amendola Gianluca , Dimino Ignazio , Concilio Antonio , Pecora Rosario , Amoroso Francesco
Published: November 2017

Airfoil camber adaptation may be the key for the performance improvement of wings for many specific applications, including shorter take-off distance, compensation of weight variation and so on. Following the successful experiences gained in SARISTU, where an adaptive trailing edge device was developed for medium to large size commercial aircraft, the authors propose to exploit the developed architecture to a small aircraft wing. The basic reasons behind that mainly rely on the associated possibility to access easier implementation onto a real aircraft instead of referring to wing segments for wind tunnel or ground tests. In this way, many operative problems are faced, that would be otherwise neglected in usual lab experimentation. First of all, the integration of the proposed device onto a flying machine, that in turn pose the problem of facing the interface with the existing systems. Secondly, the necessity of including the device into the flap while fully preserving its current functionality. Furthermore, the necessity of developing a robust design process that allows having the release of the permit-to-fly. Each of the above steps, non-exhaustive in illustrating the difficulty of the addressed challenge, is structured in many other sub-segments, ranging from a suitable FHA analysis to a full re-design of the existing high lift systems or the adaptation of the architecture of the reference morphing trailing edge itself. This last item poses the classical challenge of the scaling issues, requiring the structural and the actuation subsystems to entirely fit into the new geometry. The objective of the present research is then to verify the feasibility of applying a certain architectural morphing philosophy onto a real aircraft, taking into account all the operational difficulties related to such an operation. This paper reports the activities related to the exploitation of the reference adaptive structural architecture, to the geometry of a flap of a small aircraft. In detail, the system layout is presented, followed by a FE analysis of the structural system under the operational loads and an estimation of the weight penalty associated to this transformation. Interfaces of the flap system with the main aircraft body are considered as constraints to the design development, so that the only flap is affected.
Experimental Evidence of Vibrational Resonance in a Bi-Stable Twin-Well Mechanical Oscillator
Authors: Abusoua Abdraouf , Daqaq Mohammed F.
Published: November 2017

Vibrational Resonance (VR) is a nonlinear phenomenon which occurs when a bi-stable system is subjected to a bi-harmonic excitation consisting of a small-amplitude resonant excitation and a large-amplitude high-frequency excitation. The result is that, under some conditions, the high-frequency excitation amplifies the resonant response associated with the slow dynamics. While VR was studied extensively in the open literature, most of the research studies used optical and electrical systems as platforms for experimental investigation. This paper provides experimental evidence that VR can also occur in a mechanical bi-stable twin-well oscillator and discusses the conditions under which VR is possible.
Magnetic Field Within a Magnetic Shape Memory Alloy and an Equivalent Uniform Applied Magnetic Field for Model Input
Authors: Eberle J. Lance , Feigenbaum Heidi P. , Ciocanel Constantin
Published: November 2017

Magnetic shape memory alloys (MSMAs) exhibit recoverable strains of up to 10% due to reorientation of their martensitic tetragonal unit cell. A stress or magnetic field applied to the material will cause the short side of the unit cell (which is approximately aligned with the magnetic easy axis) to align with the input to the material, resulting in an apparent plastic strain. This strain can be fully recovered by an applied stress or magnetic field in a perpendicular direction.

When the martensitic variants reorient, twin boundaries, which separate the different variants, form and move throughout the specimen. A number of models have been proposed for MSMAs and many of these models are homogenized, i.e. the models do not account for twin boundaries, but rather account for the volume fraction of material in each variant. These types of models often assume that the MSMA is subject to a uniform field so that there is no appreciable difference in the volume fraction of variants in each location. In this work, we address the issue of how these models can be used when the field is not uniform.

In particular, we look at the experiments from Feigenbaum et al., in which a MSMA trained to accommodate three variants, was subject to 3-dimensional magneto-mechanical loading. Due to experimental constraints, the field applied to the MSMA was not uniform. In this work, to understand the actual field distribution during experiments, we performed a high-resolution 3-dimensional finite element analysis (FEA) of the magnetic field experienced by the MSMA sample. The FEA allowed us to determine how non-uniform the experimentally applied field was and the differences between the applied field and the field experienced by the MSMA. Furthermore, we use the FEA to determine the average field experienced by the MSMA, and identify an equivalent uniform applied field that could serve as input for the model. For the latter, we seek a uniform magnetic field which gives similar magnetic field within the MSMA specimen as the true experimental conditions.
Localized Damage Identification of Plate-Like Structures With Time-Delayed Binary Data From a Self-Powered Sensor Network
Authors: Salehi Hadi , Burgueño Rigoberto , Das Saptarshi , Biswas Subir , Chakrabartty Shantanu
Published: November 2017

Recent advances in energy harvesting technologies have led to the development of self-powered monitoring techniques that are energy-efficient. This study presents an intelligent damage identification strategy for plate-like structures based on the data provided by a network of self-powered sensors that communicate through a pulse switching protocol, which has been demonstrated as an effective means for minimizing communication energy demands. The energy-aware pulse switching communication architecture uses single pulses instead of multi-bit packets for information delivery, resulting in discrete binary data. A system employing such an energy-efficient technology requires dealing with power budgets for sensing and communication of binary data, which leads to time delay constraints. In this paper, a novel machine learning framework incorporating low-rank matrix decomposition, pattern recognition, and a statistical approach is proposed to overcome challenges inherent in algorithm design for damage identification using time-delayed binary data. Performance and effectiveness of the proposed energy-aware damage identification strategy was examined for the case of a dynamically loaded plate. Damage states were simulated on a finite element model by reducing stiffness in a region of the plate. Results show that the presence and location of the damage can be effectively identified even with noisy features and missing data. The performance and applicability of the proposed localized damage detection strategy for plate-like structures using discrete time-delayed binary data from a novel wireless sensor network is thus demonstrated.
Dynamics of Hybrid Mechanical-Electromechanical Locally Resonant Piezoelectric Metastructures
Authors: Sugino Christopher , Ruzzene Massimo , Erturk Alper
Published: November 2017

Locally resonant metamaterials are characterized by bandgaps at wavelengths much larger than the lattice size, which enables low-frequency vibration attenuation in structures. Next-generation metastructures (i.e. finite metamaterial-based structures) hosting mechanical resonators as well as piezoelectric interfaces connected to resonating circuits enable the formation of two bandgaps, right above and below the design frequency of the mechanical and electrical resonators, respectively. This new class of hybrid metastructures proposed in this work can therefore exhibit a wider bandgap size and enhanced design flexibility as compared to using a purely mechanical, or a purely electromechanical metastructure alone. To this end, we bridge our efforts on modal analysis of mechanical and electromechanical locally resonant metastructures and establish a fully coupled framework for hybrid mechanical-electromechanical metastructures. Combined bandgap size is approximated in closed form for sufficient number of mechanical and electromechanical resonators. Case studies are presented to understand the interaction of these two locally resonating metastructure domains in bandgap formation, and conclusions are drawn for design and optimization of such hybrid metastructures. Numerical results from modal analysis are compared with dispersion analysis using the plane wave expansion method and the proposed analytical framework is validated succesfully.
Reversible Actuation of Origami Inspired Composites Using Liquid Crystal Elastomers
Authors: Minori A. , Jadhav S. , He Q. , Cai S. , Tolley M. T.
Published: November 2017

Recent work has used self-folding origami inspired composites to produce complex, scalable, affordable, and lightweight morphing structures [1]. These characteristics are of interest for engineering applications, in fields including aerospace [2] and medical devices [3]. Due to these advantages, research on self-folding smart composites has grown, with a particular focus on the use of laminate manufacturing techniques that stack layers of heterogeneous materials to generate functional composites. Previous work used this approach to manufacture self-folding origami inspired robots [1]. A simple shape memory composite design consists of a smart material (e.g. a one-way shape memory polymer, or SMP) sandwiched between patterned rigid layers. These SMPs change their shape in response to an external stimulus (e.g. temperature). Upon heating above the phase transition temperature of the polymer (Tt), the SMP contracts, causing the laminate to fold. The SMPs used in self-folding laminate composites are unidirectional and thus the laminate is unable to recover its original state without application of external force. In this work, we study the use of thermal responsive liquid crystal elastomers (LCE) for reversible self-folding and actuation of origami inspired composites using laminate manufacturing. LCEs are smart materials that exhibit reversible deformation, good strain recoverability, and tailorable properties (i.e. phase transition temperature, strain, and orientation of deformation) [4–6]. We explore two composite hinge designs using laminate manufacturing process [1, 7] with a Joule heating layer to enable self-folding: one where the LCE acts as a tensile actuator connected only on the edges of the rigid layer, which we call a tensional hinge, and a second where the LCE is attached along the patterned rigid layer hinge, which we call a flexural hinge. The angular displacements of these two hinge designs are estimated using geometric models that account for the contraction of the LCE upon heating, and compared against experimental measurements. The maximum blocked torque of the composite hinges is also measured experimentally. To demonstrate the use of LCE as an active layer for origami inspired composites, we also present a laminate crawler robot. The crawling locomotion is controlled with an electrical heating layer laminated on the LCE. These results demonstrate the possibility of using LCE to achieve rapid, reversible folding and to generate similar torques, as compared to previous work in origami inspired self-folding composite.
Parametric Studies of Geometric Design Factors on Static and Dynamic Loading of an Origami Flasher
Authors: Hossain Bhuiyan Md Emran , Semer Daniel , Trease Brian P.
Published: November 2017

The “flasher” pattern (an origami base that folds into a 3D structure that can be radially deployed into a 2D surface) has been recognized for its potential application in the deployment of large structures from relatively small volumes. Such structures can be internally deployed by smart materials or stored strain energy, or externally deployed by actuators or inertial forces. Various flasher folding patterns can be created by varying three basic geometric parameters: (1) the number of sides of the center polygon, (2) the number of rings comprising the array, and (3) the number of radially-distributed elements of each ring. In this paper, these three parameters are studied for their effect on dynamic performance, using multi-body dynamic (MBD) simulation software. As a basis for comparison, all the designs are held to the same surface area in the deployed flat state. Each MBD model is created automatically by a series of previously reported scripts that transform a crease pattern into a fully defined engineering model. The primary focus is to investigate the variation of (a) the deployment time, (b) reaction torque at the center of the flasher, (c) force and torque distribution in the entire structure, (d) bending angle of the panels, and (e) rigid foldability. An experimental test-bed is also described, with provision of preliminary physical validation results. The overall effort provides insight to force distribution within the structure, which can guide the placement of integrated smart material actuators. The results also help in flasher design parameter decisions by giving insight into their effect on future applications such as star occulter designs, solar arrays, solar reflectors, sunshields, smallsat antennas, and solar sails.
On the Dielectrophoretic and Magnetic Alignment of Magnetoactive Barium Hexaferrite-PDMS Nanocomposites
Authors: Masud Md Abdulla Al , D’Souza Noel , von Lockette Paris , Ounaies Zoubeida
Published: November 2017

In this study, we demonstrate the electric and magnetic manipulation of nanoscale M-type Barium Hexaferrite (nBF) in polydimethylsiloxane (PDMS) to engineer a multifunctional nanocomposite with improved dielectric and magnetic properties. First, we synthesized the single crystal nBF via the hydrothermal synthesis route. The hydrothermal temperature, duration, and surfactant conditions were optimized to improve the magnetic properties of the nBFs, with further improvement achieved by post-annealing. The annealed nBFs were aligned dielectrophoretically (DEP) in the polymer matrices by applying an AC electric field. Under the influence of this electric field, nBFs were observed to rotate, align and form chains within the polymer matrix. Optical microscopy (OM) imaging was used to determine the electrical alignment conditions (duration, magnitude, and frequency) and these parameters were used to fabricate the composites. A Teflon setup with Indium Tin Oxide (ITO) coated Polyethylene Terephthalate (PET) was used, where the ITO coatings act as electrodes for the electric field-manipulation. To simultaneously apply the magnetic field, this Teflon setup is placed between two permanent magnets capable of generating a 0.6 T external magnetic field. Along with electric and magnetic fields, concurrent heating was applied to cure the PDMS and freeze the microstructure formed due to electric and magnetic fields. Upon completion of the curing step, parallel chain formation is observed under OM. The X-Ray Diffraction (XRD) results also confirm that the particles are magnetically oriented in the direction of the magnetic field within the chain. Vibrating Sample Magnetometry (VSM) measurements and dielectric spectroscopy are used to characterize the extent of anisotropy and improvement in dielectric and magnetic properties compared to random composites. We find that simultaneous electric and magnetic field alignment improves the dielectric properties by 12% compared to just magnetic alignment. We also observe 19% improved squareness ratio when both fields are applied. The possibility of simultaneous electrical and magnetic alignment of magnetic nanoparticles will open up new doors to manipulate and design particle-modified polymers for various applications.
Supporting struggling students on placement: A practical guide
Authors: Finch Jo
Published: November 2017

Reviewed by Cherie Appleton.
Quantification of stiffness measurement errors in resonant ultrasound spectroscopy of human cortical bone
Authors: Cai Xiran , Peralta Laura , Gouttenoire Pierre-Jean , Olivier Cécile , Peyrin Françoise , Laugier Pascal , Grimal Quentin
Published: November 2017

Resonant ultrasound spectroscopy (RUS) is the state-of-the-art method used to investigate the elastic properties of anisotropic solids. Recently, RUS was applied to measure human cortical bone, an anisotropic material with low Q-factor (20), which is challenging due to the difficulty in retrieving resonant frequencies. Determining the precision of the estimated stiffness constants is not straightforward because RUS is an indirect method involving minimizing the distance between measured and calculated resonant frequencies using a model. This work was motivated by the need to quantify the errors on stiffness constants due to different error sources in RUS, including uncertainties on the resonant frequencies and specimen dimensions and imperfect rectangular parallelepiped (RP) specimen geometry. The errors were first investigated using Monte Carlo simulations with typical uncertainty values of experimentally measured resonant frequencies and dimensions assuming a perfect RP geometry. Second, the exact specimen geometry of a set of bone specimens were recorded by synchrotron radiation micro-computed tomography. Then, a “virtual” RUS experiment is proposed to quantify the errors induced by imperfect geometry. Results show that for a bone specimen of ∼1° perpendicularity and parallelism errors, an accuracy of a few percent (<6.2%) for all the stiffness constants and engineering moduli is achievable.
REVIEWS OF ACOUSTICAL PATENTS
Authors: Fulop Sean A. , Rice Lloyd
Published: November 2017

The purpose of these acoustical patent reviews is to provide enough information for a Journal reader to decide whether to seek more information from the patent itself. Any opinions expressed here are those of the reviewers as individuals and are not legal opinions. Printed copies of United States Patents may be ordered at $3.00 each from the Commissioner of Patents and Trademarks, Washington, DC 20231. Patents are available via the Internet at http://www.uspto.gov.
Polarizing head of House science panel to retire
Authors: Mervis Jeffrey
Published: November 2017

Texan Lamar Smith helped stoke fierce fights over climate change, peer review, and funding
Medical centers spearhead China's pharma push
Authors: Normile Dennis
Published: November 2017

Nation hopes reforms will yield more and better drugs
The perfect wave
Authors: Cohen Jon
Published: November 2017

A scientist and a surfer team up to convert a landlocked lake into
The
Endless Summer
dream
Killer clones
Authors: Leslie Mitch
Published: November 2017

Overgrowth of mutant blood cells is common in older people—and a risk factor for serious disease
Genomic history of the seventh pandemic of cholera in Africa
Authors: Weill François-Xavier , Domman Daryl , Njamkepo Elisabeth , Tarr Cheryl , Rauzier Jean , Fawal Nizar , Keddy Karen H. , Salje Henrik , Moore Sandra , Mukhopadhyay Asish K. , Bercion Raymond , Luquero Francisco J. , Ngandjio Antoinette , Dosso Mireille , Monakhova Elena , Garin Benoit , Bouchier Christiane , Pazzani Carlo , Mutreja Ankur , Grunow Roland , Sidikou Fati , Bonte Laurence , Breurec Sébastien , Damian Maria , Njanpop-Lafourcade Berthe-Marie , Sapriel Guillaume , Page Anne-Laure , Hamze Monzer , Henkens Myriam , Chowdhury Goutam , Mengel Martin , Koeck Jean-Louis , Fournier Jean-Michel , Dougan Gordon , Grimont Patrick A. D. , Parkhill Julian , Holt Kathryn E. , Piarroux Renaud , Ramamurthy Thandavarayan , Quilici Marie-Laure , Thomson Nicholas R.
Published: November 2017

Wave upon wave of disease

The cholera pathogen,
Vibrio cholerae
, is considered to be ubiquitous in water systems, making the design of eradication measures apparently fruitless. Nevertheless, local and global
Vibrio
populations remain distinct. Now, Weill
et al.
and Domman
et al.
show that a surprising diversity between continents has been established. Latin America and Africa bear different variants of cholera toxin with different transmission dynamics and ecological niches. The data are not consistent with the establishment of long-term reservoirs of pandemic cholera or with a relationship to climate events.

Science
, this issue p.
785
, p.
789
Promises and challenges of perovskite solar cells
Authors: Correa-Baena Juan-Pablo , Saliba Michael , Buonassisi Tonio , Grätzel Michael , Abate Antonio , Tress Wolfgang , Hagfeldt Anders
Published: November 2017

The efficiencies of perovskite solar cells have gone from single digits to a certified 22.1% in a few years’ time. At this stage of their development, the key issues concern how to achieve further improvements in efficiency and long-term stability. We review recent developments in the quest to improve the current state of the art. Because photocurrents are near the theoretical maximum, our focus is on efforts to increase open-circuit voltage by means of improving charge-selective contacts and charge carrier lifetimes in perovskites via processes such as ion tailoring. The challenges associated with long-term perovskite solar cell device stability include the role of testing protocols, ionic movement affecting performance metrics over extended periods of time, and determination of the best ways to counteract degradation mechanisms.
Perovskites in catalysis and electrocatalysis
Authors: Hwang Jonathan , Rao Reshma R. , Giordano Livia , Katayama Yu , Yu Yang , Shao-Horn Yang
Published: November 2017

Catalysts for chemical and electrochemical reactions underpin many aspects of modern technology and industry, from energy storage and conversion to toxic emissions abatement to chemical and materials synthesis. This role necessitates the design of highly active, stable, yet earth-abundant heterogeneous catalysts. In this Review, we present the perovskite oxide family as a basis for developing such catalysts for (electro)chemical conversions spanning carbon, nitrogen, and oxygen chemistries. A framework for rationalizing activity trends and guiding perovskite oxide catalyst design is described, followed by illustrations of how a robust understanding of perovskite electronic structure provides fundamental insights into activity, stability, and mechanism in oxygen electrocatalysis. We conclude by outlining how these insights open experimental and computational opportunities to expand the compositional and chemical reaction space for next-generation perovskite catalysts.
Engineered emotions
Living with Robots
Paul Dumouchel and Luisa Damiano
Harvard University Press, 2017. 280 pp.
Authors: Quinon Paula
Published: November 2017

A pair of philosophers probe the ethical implications of designing social robots
Linking smell to metabolism and aging
Authors: Garrison Jennifer L. , Knight Zachary A.
Published: November 2017

The olfactory system can have direct effects on energy homeostasis
A generic interface to reduce the efficiency-stability-cost gap of perovskite solar cells
Authors: Hou Yi , Du Xiaoyan , Scheiner Simon , McMeekin David P. , Wang Zhiping , Li Ning , Killian Manuela S. , Chen Haiwei , Richter Moses , Levchuk Ievgen , Schrenker Nadine , Spiecker Erdmann , Stubhan Tobias , Luechinger Norman A. , Hirsch Andreas , Schmuki Patrik , Steinrück Hans-Peter , Fink Rainer H. , Halik Marcus , Snaith Henry J. , Brabec Christoph J.
Published: November 2017

Minimizing losses at interfaces

Among the issues facing the practical use of hybrid organohalide lead perovskite solar cells is the loss of charge carriers at interfaces. Hou
et al.
show that tantalum-doped tungsten oxide forms almost ohmic contacts with inexpensive conjugated polymer multilayers to create a hole-transporting material with a small interface barrier. This approach eliminates the use of ionic dopants that compromise device stability. Solar cells made with these contacts achieved maximum efficiencies of 21.2% and operated stably for more than 1000 hours.

Science
, this issue p.
1192
Photoredox-catalyzed deuteration and tritiation of pharmaceutical compounds
Authors: Loh Yong Yao , Nagao Kazunori , Hoover Andrew J. , Hesk David , Rivera Nelo R. , Colletti Steven L. , Davies Ian W. , MacMillan David W. C.
Published: November 2017

Lighting the way to drug labeling

It is important during drug development to study how candidate compounds get absorbed and broken down biologically. One common technique for tracking a drug's fate is to label its molecular framework with heavier isotopes of hydrogen (either deuterium or tritium). Loh
et al.
developed a light-promoted protocol to install these labels on alkyl carbons adjacent to nitrogen. The technique relies on incorporation of the heavy isotope into a thiol from a convenient heavy water source through acid-base chemistry. Next, a photoredox catalyst strips a hydrogen atom equivalent from the carbon, and the thiol engages in radical chemistry to transfer the deuterium or tritium in its place.

Science
, this issue p.
1182
Tricks for noncovalent catalysis
Authors: Mattson Anita E.
Published: November 2017

Hydrogen-bond donors activate Lewis acids to catalyze stereoselective synthesis
Complete Annotated Genome Sequences of Four Klebsiella pneumoniae Phages Isolated from Sewage in Poland
Authors: Labudda Łukasz , Strapagiel Dominik , Karczewska-Golec Joanna , Golec Piotr
Published: November 2017

Four lytic phages, vB_KpnP_BIS33, vB_KpnP_IL33, and vB_KpnP_PRA33 of the
Podoviridae
family and vB_KpnM_BIS47 of the
Myoviridae
family, which act against animal-pathogenic
Klebsiella pneumoniae
strains, were isolated from sewage plants in Poland. They possess double-stranded DNA genomes of 41,697 bp, 41,335 bp, 40,605 bp, and 147,443 bp, respectively.
Whole-Genome Sequences of Variants of Bacillus anthracis Sterne and Their Toxin Gene Deletion Mutants
Authors: Staab A. , Plaut R. D. , Pratt C. , Lovett S. P. , Wiley M. R. , Biggs T. D. , Bernhards R. C. , Beck L. C. , Palacios G. F. , Stibitz S. , Jones K. L. , Goodwin B. G. , Smith M. A. , Sozhamannan S.
Published: November 2017

Here, we report the draft genome sequences of three laboratory variants of
Bacillus anthracis
Sterne and their double (
Δlef Δcya
) and triple (
Δpag Δlef Δcya
) toxin gene deletion derivatives.
Complete Genome Sequence of the Fruiting Myxobacterium Melittangium boletus DSM 14713
Authors: Treuner-Lange Anke , Bruckskotten Marc , Rupp Oliver , Goesmann Alexander , Søgaard-Andersen Lotte
Published: November 2017

The formation of spore-filled fruiting bodies in response to starvation represents a hallmark of many members of the order
Myxococcales
. Here, we present the complete 9.9-Mb genome of the fruiting type strain
Melittangium boletus
DSM 14713, the first member of this genus to have its genome sequenced.
Referrals to a perinatal specialist palliative care consult service in Ireland, 2012–2015
Authors: McMahon Des L , Twomey Marie , O’Reilly Maeve , Devins Mary
Published: November 2017

Objective

To analyse the referral patterns of perinatal patients referred to a specialist palliative care service (SPCS), their demographics, diagnoses, duration of illness, place of death and symptom profile.

Design

A retrospective chart review of all perinatal referrals over a 4-year period to the end of 2015.

Setting

A consultant-led paediatric SPCS at Our Lady’s Children’s Hospital, Crumlin, Dublin, and the Coombe Women & Infants University Hospital, Dublin.

Results

83 perinatal referrals were received in a 4-year period. Chromosomal abnormalities accounted for 35% of diagnoses, congenital heart disease 25%, complex neurological abnormalities 11% and renal agenesis 4%. 22 referrals (26.5%) were made antenatally, with 61 (73.5%) postnatally. Of the postnatal referrals, 27 (44%) were asymptomatic on referral. An opioid medication was recommended (regularly or as required) in 46 cases. Symptom control was achieved without dose titration in 43 of these cases (93%). Of 47 deaths in this group referred postnatally, 22 of these (47%) died at home with support from community teams. Discharge home for best supportive care required complex interagency communication and cooperation.

Conclusions

Perinatal palliative care requires effective multidisciplinary work, whether delivered in the inpatient setting or in the community. With appropriate support, end-of-life care can be delivered in the community.
Retrospective cohort analysis on pancreatic enzyme substitution in very low birthweight infants with postnatal growth failure
Authors: Ziegler Julian O , Maas Christoph , Bernhard Wolfgang , Arand Joerg , Poets Christian F , Franz Axel R
Published: November 2017

Objective

To evaluate the effects of pancreatic enzyme substitution (PES) in selected very low birthweight (VLBW) infants with poor postnatal growth despite intensified nutritional support.

Design

Retrospective historic cohort study with matched controls.

Setting

Single level III neonatal intensive care unit.

Patients

Infants with a gestational age at birth <32 weeks and birth weight <1500 g born between 1 January 2005 and 31 December 2014 (n=26) who received PES for restricted postnatal growth despite intensified enteral nutritional support in comparison with infants matched for birth weight, birth year, gestational and postnatal age (n=52).

Interventions

PES 15–93 mg/g fat with enteral feeds.

Main outcome measures

The difference in SD score (SDS) differences for weight during the 7 days before and after onset of PES and weight gain in g/kg/d. Data are presented as median (P10–P90).

Results

Gestational age was 26.6 (24.4–29.9) weeks in enzyme substituted versus 26.4 (24.7–29.9) weeks in matched controls, and birth weight was 648(420–950)g versus 685(453–949)g. SDS differences for weight improved after onset of PES by 0.18(−0.12 to 0.53) in PES infants versus −0.04(−0.31 to 0.44) in controls. Weight gain increased in the PES group from 13.6 (4.2–22.9) g/kg/day in the week before to 19.0 (10.9–29.1) g/kg/day in the week after the onset of PES. There was no difference in weight gain in substituted subgroups receiving formula/pasteurised human milk versus unpasteurised human breast milk or who had pancreatic-specific elastase-1 concentrations in stool >200 µg/g versus≤200 µg/g. No adverse effects were noted.

Conclusions

PES in selected VLBW infants with growth failure despite intensified enteral nutritional support was associated with a significant increase in weight gain in the first 7 days of PES.k
Dyspnoea in lupus
Authors: Fleri Soler Jeremy , Borg Andrew , Mercieca Cecilia
Published: November 2017

A 32-year-old woman suffering from systemic lupus erythematosus presented with a 6-week history of progressive dyspnoea and pleuritic chest pain. Examination was normal apart from reduced air entry at the lung bases.

Arterial blood gases showed hypoxaemia and chest X-ray revealed raised hemidiaphragms without any pleural effusions. Lung function showed a restrictive pathology while high-resolution chest CT and CT pulmonary angiogram were negative. Echocardiography showed normal ventricular diameters and no pericardial effusion. Reduced lung volumes and a positive fluoroscopic sniff test lead to a diagnosis of shrinking lung syndrome. Symptoms improved following treatment with glucocorticoids and non-invasive ventilation, but there was no change in lung function.

A year later, our patient presented again with worsening dyspnoea. This time echocardiography revealed severe mitral stenosis with pulmonary hypertension. Mitral valve replacement was performed and dyspnoea resolved. Histology showed Libman-Sachs endocarditis.
Comparative evaluation of progression rate in keratoconus before and after collagen crosslinking
Authors: Wang Yu Meng , Chan Tommy CY , Yu Marco C Y , Jhanji Vishal
Published: November 2017

Purpose

To compare the rate of disease progression in keratoconus before and after corneal collagen crosslinking (CXL).

Methods

145 eyes were followed without CXL (no-CXL group) for a median duration of 31 months whereas 45 eyes were followed up for 41 months before (pre-CXL) and after (post-CXL) accelerated, epithelium-off crosslinking. Progression was defined based on significant slope found in linear mixed effect models against time. Swept-source optical coherence tomography was used for measurement of anterior steep keratometry, anterior flat keratometry (Ant Kf), anterior average keratometry (Ant Avg K); posterior steep keratometry, posteriorflat keratometry (Post Kf), posterior average keratometry (Post Avg K) and corneal thickness.

Results

The patients in pre-CXL group were significantly younger (26.3±5.48 years) compared with the patients in no-CXL group (32.7±10.24 years) (P=0.004). Significant differences were observed during baseline examination for all parameters (P≤0.035) between pre-CXL and no-CXL groups except Ant Cyl and Post Cyl. During observation period, statistically significant differences were noted between pre-CXL and no-CXL groups in the progression rate of Ant Kf, Ant Avg K, Post Kf and Post Avg K (P≤0.045). After CXL, the progression rate in post-CXL group was comparable to that in no-CXL group. All corneal parameters remained stable in no-CXL group throughout the follow-up period.

Conclusions

Serial tomographic examination is useful to document disease progression before and after CXL. In our study, a decrease in progression rate of corneal parameters was noted after CXL. In cases with stable corneal parameters over time, careful monitoring can be considered instead of collagen crosslinking.
Treatment of conjunctival melanoma in a Dutch referral centre
Authors: Brouwer Niels J , Marinkovic Marina , van Duinen Sjoerd G , Bleeker Jaco C , Jager Martine J , Luyten Gregorius P M
Published: November 2017

Aims

To evaluate the treatment of conjunctival melanoma at a large Dutch referral centre and to make recommendations for clinical management.

Methods

A retrospective review was performed of clinical and histological data of 70 patients treated for a primary conjunctival melanoma between 2001 and 2014 at the Leiden University Medical Center, Leiden, the Netherlands. Detailed follow-up data were available for all patients.

Results

The mean follow-up time was 70.2 months. The overall 5-year recurrence rate was 29%, the 5-year metastasis rate 12% and the 5-year melanoma-related survival 90%. Treatment with excision alone had a significantly higher 5-year recurrence rate than (the combination of) other treatments (HR 3.73,95% CI 1.19 to 11.6, P=0.02). Initial treatment in an ocular oncology centre was associated with fewer recurrences compared with initial treatment by a local ophthalmologist of a referring centre (HR 0.32,95% CI 0.11 to 0.94, P=0.04), despite similar tumour baseline characteristics.

Conclusion

Conjunctival melanoma is a rare disease with a high recurrence rate. A treatment strategy with local excision and adjuvant therapy gave a good clinical outcome, excision alone as a treatment should be considered obsolete. Initial treatment in a large referral centre improves clinical outcome, and patients should be referred to a specialised centre as soon as possible.
Type 2 diabetes in general practice in Norway 2005–2014: moderate improvements in risk factor control but still major gaps in complication screening
Authors: Bakke Åsne , Cooper John G , Thue Geir , Skeie Svein , Carlsen Siri , Dalen Ingvild , Løvaas Karianne Fjeld , Madsen Tone Vonheim , Oord Ellen Renate , Berg Tore Julsrud , Claudi Tor , Tran Anh Thi , Gjelsvik Bjørn , Jenum Anne Karen , Sandberg Sverre
Published: November 2017

Objective

To assess the status of type 2 diabetes care in general practice and changes in the quality of care between 2005 and 2014, and to identify areas of diabetes care requiring improvement.

Research design and methods

Two cross-sectional surveys were performed that included patients with type 2 diabetes in selected areas (n=9464 in 2014, n=5463 in 2005). Quality of care was assessed based on key recommendations in national guidelines. Differences in clinical performance between 2005 and 2014 were assessed in regression models adjusting for age, sex, counties and clustering within general practices.

Results

Treatment targets were achieved in a higher proportion of patients in 2014 compared with 2005: hemoglobin A1c ≤7.0% (≤53 mmol/mol) in 62.8% vs 54.3%, blood pressure ≤135/80 mm Hg in 44.9% vs 36.6%, and total cholesterol ≤4.5 mmol/L in 49.9% vs 33.5% (all adjusted P≤0.001). Regarding screening procedures for microvascular complications, fewer patients had recorded an eye examination (61.0% vs 71.5%, adjusted P<0.001), whereas more patients underwent monofilament test (25.9% vs 18.7%, adjusted P<0.001). Testing for albuminuria remained low (30.3%) in 2014. A still high percentage were current smokers (22.7%).

Conclusions

We found moderate improvements in risk factor control for patients with type 2 diabetes in general practice during the last decade, which are similar to improvements reported in other countries. We report major gaps in the performance of recommended screening procedures to detect microvascular complications. The proportion of daily smokers remains high. We suggest incentives to promote further improvements in diabetes care in Norway.