bluuebunny/crossref_metadata_2025 huggingface dataset:
Rückgewinnung anorganischer Wertstoffe mit Bordotierten Diamantelektroden
Authors: Weidlich Claudia , Greb Valentin , Fröhlich Peter , Bertau Martin , Mangold Klaus‐Michael
Published: January 2017

Aufgrund begrenzter Primärvorkommen bei gleichzeitig steigendem Bedarf an verschiedenen Metallen wird die Nutzung von Sekundärrohstoffen zunehmend wichtiger. Mit einem neuen, elektrochemischen Verfahren können aus verschiedenen Abfällen und Rückständen, wie z. B. Klärschlammaschen, Verbrennungsschlacken und Haldenmaterialien, metallische Wertstoffe wie Kupfer, Zink und Nickel gelöst und zurückgewonnen werden. Dazu werden in Mineralsäuren mit bordotierten Diamantelektroden Persäuren erzeugt, die eine signifikant höhere Mobilisierung der Wertstoffe ermöglichen.
An effective pseudospectral optimization approach with sparse variable time nodes for maximum production of chemical engineering problems
Authors: Xiao Long , Liu Xinggao
Published: January 2017

An effective pseudospectral method is proposed for dynamic optimization problems, the aim of which is to maximize production of these problems in chemical engineering. Several variable time nodes are considered to be optimization variables in the whole time horizon to obtain a precise localization of the switching points of the optimal control profiles. To ensure accuracy, the intervals between the variable time nodes are further divided into multiple subintervals uniformly. Then the state and the control vector are all parameterized. To improve the efficiency, the sensitivities of the states with respect to the controls and the variable time nodes are derived from the solution of the discretized dynamic system. Three chemical dynamic optimization problems are tested as an illustration. The detailed comparisons between the proposed method and the methods reported in the literature are also carried out. The research results reveal the effectiveness of the proposed approach.
Why Are Dithienylethene‐Linked Biscobaltocenes so Hard to Photoswitch?
Authors: Escribano Alejandra , Steenbock Torben , Stork Conrad , Herrmann Carmen , Heck Jürgen
Published: January 2017

Attaching an organometallic unit to a dithienylethene (DTE) molecular switch can allow one to vary its switching and spectroscopic properties, and to create switchable magnetic properties. In this work, two different dithienylethene molecular switches are used as a bridge between two cobalt sandwich units. The only difference between the switching cores is in the size of the cycloalkene ring connecting both thiophene rings. The complexes present different oxidation states for the cobalt atoms, which are demonstrated to determine the switching reaction. The UV/Vis measurements show that while the Co(I) complexes undergo the switching reaction, the Co(II,III) complexes switch poorly. Kohn–Sham density functional theory calculations indicate diabatic ring‐closure mechanisms and a large number of excited states hindering the cyclization reaction and favoring the relaxation to the open form of the molecular switch.
Differentiate needs to better support autistic students
Authors: Sutton Halley
Published: January 2017

Marc Ellison, Ed.D., began working with individuals diagnosed with autism spectrum disorder as an undergraduate student at Marshall University. There, Ellison collaborated with the West Virginia Autism Training Center, which in 2002 created the first university‐based support program for matriculated college students diagnosed with ASD. In 2013, Ellison became the executive director of the West Virginia Autism Training Center, which now supports more than 50 students per semester at Marshall.
Privacy, disability, and health science students
Authors: Jain Neera R. , Meeks Lisa M.
Published: January 2017

We are often asked to address students' concerns about confidentiality and privacy related to their disability status in high‐stakes health professions programs. Some students may have expectations about confidentiality practices based on their experience in health care settings. Stigma can also be a barrier to seeking accommodations in these programs as students often describe concerns about who will know about their disability and who will have access to their disability documentation. As future health professionals, students are understandably concerned that their documentation and disability status could be used against them in their career (e.g., inability to get malpractice insurance, inability to get licensed, concern with documentation being accessed in malpractice suits).
Exploring Text and Icon Graph Interpretation in Students with Dyslexia: An Eye‐tracking Study
Authors: Kim Sunjung , Wiseheart Rebecca
Published: January 2017

A growing body of research suggests that individuals with dyslexia struggle to use graphs efficiently. Given the persistence of orthographic processing deficits in dyslexia, this study tested whether graph interpretation deficits in dyslexia are directly related to difficulties processing the orthographic components of graphs (i.e. axes and legend labels). Participants were 80 college students with and without dyslexia. Response times and eye movements were recorded as students answered comprehension questions about simple data displayed in bar graphs. Axes and legends were labelled either with words (mixed‐modality graphs) or icons (orthography‐free graphs). Students also answered informationally equivalent questions presented in sentences (orthography‐only condition). Response times were slower in the dyslexic group only for processing sentences. However, eye tracking data revealed group differences for processing mixed‐modality graphs, whereas no group differences were found for the orthography‐free graphs. When processing bar graphs, students with dyslexia differ from their able reading peers only when graphs contain orthographic features. Implications for processing informational text are discussed. Copyright © 2017 John Wiley & Sons, Ltd.
Novel Transmitting Power Control Method without Signal Communication for Wireless Power Transfer via Magnetic Resonance Coupling
Authors: GUNJI DAISUKE , IMURA TAKEHIRO , FUJIMOTO HIROSHI
Published: January 2017

Wireless power transfer (WPT) via magnetic resonance coupling has been widely studied for vehicle applications, particularly the stationary and dynamic charging of electric vehicles. Our research group previously proposed a wireless in‐wheel motor to improve the reliability and safety of in‐wheel motors. Transmit power control is necessary to achieve stable WPT. We proposed a control method that uses a feedforward controller on the primary side and a feedback controller on the secondary side. However, the control method may cause shortfalls in the transmission power owing to modeling error, coupling coefficient variation, and signal communication delay. In this paper, we propose a novel feedback control method for the primary side based on conversion ratio estimation. The effectiveness of the proposed method was verified by simulations and experiments on the load current control of a constant voltage load and load voltage control of a constant power load.
Estimation and Kinetic Modeling of Human Arm using Wearable Robot Arm
Authors: YAMAZAKI TAKAHIRO , SAKAINO SHO , TSUJI TOSHIAKI
Published: January 2017

This paper describes an estimation method for the physical parameters of human arms. The parameters are used in the medical and kinematic analysis fields. Personal differences are important, but some of the conventional methods do not consider personal differences pertaining to inertia in viscoelasticity muscular strength measurements. The remaining conventional methods that consider personal differences require precise measurement devices. The proposed method realizes kinetics modeling and identification of the friction and inertia including the off‐diagonal parameters of human arms by using wearable robots. First, wearable robots are multi‐input devices. In addition, the actuators of wearable robots can be located near human joints and can input M‐sequence torque. Therefore, wearable robots can input signals having a high signal‐to‐noise ratio and ensuring persistently exciting characteristics in each human joint. By employing multi‐input characteristics, the proposed method can reduce patients’ burden by shortening the amount of time for estimation. In addition, we verify the accuracy of the estimated parameters by comparing the responses of the actual machine with those obtained by simulation.
Rectification Methods to Increase Harvested Energy in Vibration Generation Using Piezoelectric Elements
Authors: TANAKA TORU , AONUMA TOMOYA , NATORI KENJI , SATO YUKIHIKO
Published: January 2017

We studied vibration power generation using piezoelectric elements in order to determine effective rectification methods to increase harvested energy from vibration power generation systems. First, we experimentally clarified the output characteristics of two kinds of passive rectification methods for vibration power generation systems. Then, an appropriate rectification method for various kinds of loads was studied. In order to increase the harvested power from an integrated vibration power generation system with multiple piezoelectric elements, we considered an appropriate circuit structure for connecting multiple piezoelectric elements. The effectiveness was verified experimentally.
Cathodic Stripping Voltammetric Determination of Cerium Using Indium Tin Oxide (ITO)
Authors: Ojo Kolade , Zhao Daoli , Rusinek Cory A. , Pixley Sarah K. , Heineman William R.
Published: January 2017

Due to its numerous applications in the field of metallurgy and its role as an alloying element for slowing down the biodegradation of pure magnesium typically known to have very low corrosion resistance, the need to develop simple and inexpensive methods for determination of cerium is important. Ce3+ was determined by cathodic stripping voltammetry (CSV) using Osteryoung square‐wave voltammetry (OSWV) for the stripping step. Indium tin oxide (ITO) was used as the working electrode because of its very good positive potential range with smooth background current. Under optimized conditions, the calibration plot was linear in the concentration range of 100 nM to 700 nM Ce3+. A calculated detection limit of 5.8 nM was found for a 5 min deposition time at ITO based on the 3σ method. Interference from selected metal ions was also examined, and no significant interferences were observed. The good selectivity of this sensor makes it a good candidate for practical applications such as monitoring Ce3+ released into solution during the biodegradation of Mg−Ce alloys being developed for resorbable biomedical implants.
Very Small Inverted Hysteresis in Vacuum‐Deposited Mixed Organic–Inorganic Hybrid Perovskite Solar Cells
Authors: Erdenebileg Enkhtur , Scholz Lauren E. , Hofacker Andreas , Koerner Christian , Leo Karl
Published: January 2017

Perovskite solar cells (PSCs) have attracted great interest over the past few years due to their outstanding power conversion efficiencies. However, operational stability still needs to be improved for broad commercial application. A commonly observed phenomenon for PSCs is hysteresis in their current–voltage characteristics, which has been suggested to be related to issues with long‐term stability. A thorough understanding of the processes involved in hysteresis may also guide the way to further improving the cells’ efficiencies. We fabricate planar p–i–n organic–inorganic hybrid PSCs using three different organic transport layer architectures by vacuum deposition and measured their hysteresis and long‐term stability behavior. Our results show that vacuum‐deposited PSCs show much weaker hysteresis than in previous studies, where many types of PSCs were involved. For our devices, we also report an inverted hysteresis, where efficiency is somewhat higher for a voltage sweep from short circuit to forward‐bias conditions than for the reverse sweep at lower scan rates, which has not commonly been observed in previous studies of PSCs. Finally, we observe that up to 94 % of the initial power conversion efficiency of the encapsulated devices remained after storage in the dark for two months.
Performance Improvement of an Inhomogeneous Cathode by Infiltration
Authors: Seyed‐Vakili S. V. , Graves C. R. , Babaei A. , Heshmati‐Manesh S. , Mogensen M. B.
Published: January 2017

The performance of solid oxide fuel cells (SOFCs) is considerably influenced by the microstructure and chemical composition of cathode materials. Porous La0.85Sr0.15FeO3–Ce0.9Gd0.1O2 composite electrodes were infiltrated by La0.6Sr0.4CoO3 and La0.6Sr0.4FeO3. The effects of infiltration loading, calcination temperature of infiltrated material and co‐infiltration of LSC and LSF were investigated using electrochemical impedance measurement, microstructural analysis, and high‐temperature X‐ray diffraction (HT‐XRD). A symmetrical cell two‐electrode configuration was used to examine the electrochemical performance of the electrodes. The electrochemical results revealed that the polarization resistance of the cathodes significantly was decreased by infiltration from 2.59 to 0.034 Ω cm2 measured at 670 °C. The best electrode performance was achieved at a calcination temperature of 770 °C. It was also found that infiltration of LSC improved the stability of the electrodes during 145 h of testing at 620 °C in air at open circuit voltage (OCV).
Uncertainty of a Trump Clawback
Authors: McGuffey Mack , Pepper Rich
Published: January 2017

A new presidential administration provides an opportunity to change the course of government in Washington.
What We Might Expect From Changes in the Nation's Capital
Authors: DeCotis Paul A.
Published: January 2017

With the coming changes in Washington, with Republicans controlling the White House and both houses of Congress, one might expect drastic changes in federal energy and environmental policy. Given the president‐elect's campaign rhetoric, voters were led to believe change would be swift and impactful.
Nonstructural protein 5B promotes degradation of the NORE1A tumor suppressor to facilitate hepatitis C virus replication
Authors: Arora Payal , Basu Amartya , Schmidt M. Lee , Clark Geoffrey J. , Donninger Howard , Nichols Daniel B. , Calvisi Diego F. , Kaushik‐Basu Neerja
Published: January 2017

Hepatitis C virus (HCV) infection is a common risk factor for the development of liver cancer. The molecular mechanisms underlying this effect are only partially understood. Here, we show that the HCV protein, nonstructural protein (NS) 5B, directly binds to the tumor suppressor, NORE1A (RASSF5), and promotes its proteosomal degradation. In addition, we show that NORE1A colocalizes to sites of HCV viral replication and suppresses the replication process. Thus, NORE1A has antiviral activity, which is specifically antagonized by NS5B. Moreover, the suppression of NORE1A protein levels correlated almost perfectly with elevation of Ras activity in primary human samples. Therefore, NORE1A inactivation by NS5B may be essential for maximal HCV replication and may make a major contribution to HCV‐induced liver cancer by shifting Ras signaling away from prosenescent/proapoptotic signaling pathways. Conclusion: HCV uses NS5B to specifically suppress NORE1A, facilitating viral replication and elevated Ras signaling. (Hepatology 2017;65:1462‐1477).
Laboratory of genetics and physiology 2 (LGP2) plays an essential role in hepatitis C virus infection‐induced interferon responses
Authors: Hei Lei , Zhong Jin
Published: January 2017

Retinoic acid‐inducible gene I (RIG‐I)‐like receptors are cytosolic pattern recognition receptors (PRRs) that detect non‐self‐RNA and activate downstream interferon (IFN) signaling. One of the RIG‐I‐like receptors, laboratory of genetics and physiology 2 (LGP2), was originally thought to be a negative feedback regulator in the RIG‐I signaling pathway, but growing evidence indicates that LGP2 is one cofactor of melanoma differentiation‐associated protein 5 (MDA5) in MDA5‐mediated IFN signaling activation. Our previous work showed that MDA5 was the major PRR to sense hepatitis C virus (HCV) infection in hepatocytes, but the role of LGP2 in HCV infection‐induced IFN signaling has not been elucidated. In this study, we reported that LGP2 was a positive regulator of HCV infection‐induced IFN signaling. Knockout of LGP2 in hepatocytes significantly diminished IFN production in response to HCV infection, but not to HCV 3'untranslated region RNA transfection. Mechanistic studies showed that LGP2 exerted its function at a step upstream of MDA5 in the IFN signaling. HCV infection promoted the molecular interaction between LGP2 and MDA5, which, in turn, enhanced MDA5/HCV RNA association. Finally, we demonstrated that the ATPase activity of LGP2 was critical for assisting MDA5/HCV RNA interaction and activating IFN signaling during HCV infection. Conclusion: Our work demonstrated that LGP2 plays an essential role in activating IFN signaling against HCV infection by promoting MDA5 recognition of HCV pathogen‐associated molecular patterns. (Hepatology 2017;65:1478‐1491)
The use of instructional design guidelines to increase effectiveness of postpartum hemorrhage simulation training
Authors: de Melo Brena C.P. , Falbo Ana R. , Muijtjens Arno M.M. , van der Vleuten Cees P.M. , van Merriënboer Jeroen J.G.
Published: January 2017

Objective

To compare learning outcomes of postpartum hemorrhage simulation training based on either instructional design guidelines or best practice.

Methods

A pretest–post‐test non‐equivalent groups study was conducted among obstetrics and gynecology residents in Recife, Brazil, from June 8 to August 30, 2013. The instructional design group included 13 teams, whereas the best practice group included seven teams. A standardized task checklist was used for scenario analysis and the proportion of correctly executed tasks compared (post‐test minus pretest).

Results

The instructional design group scored higher than the best practice group for total number of tasks completed (median difference 0.46 vs 0.17; P<0.001; effect size [r]=0.72). Similar results were observed for communication (median difference 0.56 vs 0.22; P=0.004; r=0.58), laboratory evaluation (median difference 0.83 vs 0.00; P<0.001; r=0.76), and mechanical management (median difference 0.25 vs –0.15; P=0.048; r=0.39). Speed of learning was also increased. The median differences were 0.20 for the instructional design group compared with 0.05 for the best practice group at 60 seconds (P=0.015; r=0.49), and 0.49 versus 0.26 (P=0.001; r=0.65) at 360 seconds.

Conclusion

The use of simulation training for postpartum hemorrhage that was based on instructional design guidelines yielded better learning outcomes than did training based on best practice.
Similar but not consistent: Revisiting the pitfalls of measuring IgG subclasses with different assays
Authors: Ludwig‐Kraus Beatrice , Kraus Frank Bernhard
Published: January 2017

Background

Laboratory quantification of IgG subclasses (IgGSc) is a well‐established second‐line tool for differential diagnosis of immune deficiencies. However, so far there is still no internationally approved standard available for IgGSc, and different assays are prone to produce divergent results. In this study, we evaluated the comparability and equivalence of two commercially available IgGSc assays, one being the Siemens IgGSc assay on a BN ProSpec analyzer and the other being The Binding Site (TBS) IgGSc assay on a Roche cobas c502 analyzer.

Methods

We analyzed a total of 50 patient plasma samples obtained over a 3‐month period with both IgGSc assays and compared the resulting data based and the CLSI EP09‐A3 method comparison guideline.

Results

Depending on the analyzed IgGSc type, the average relative differences in IgGSc concentration (g/L) between the two assays were considerable, starting with −13.5% for IgG1 and 11.3% for IgG2, over −47.3% for IgG4, and up to 52.9% for IgG3. Applying the assay‐specific reference intervals, the classification agreement (below, within, or above the reference range) ranged from 88% to 90% for the individual subclasses. However, only 68% of samples showed an overall classification agreement.

Conclusion

The comparability of the two IgGSc assays proved to be limited and might be considered similar at best on the diagnostic level. Laboratory specialists as well as clinicians therefore should be cautious when using and interpreting IgGSc measurements obtained with different assays or analyzers.
MicroRNAs: Potential candidates for diagnosis and treatment of colorectal cancer
Authors: Moridikia Abdullah , Mirzaei Hamed , Sahebkar Amirhossein , Salimian Jafar
Published: January 2017

Colorectal cancer (CRC) is known as the third common cancer worldwide and an important public health problem in different populations. Several genetics and environmental risk factors are involved in the development and progression of CRC including chromosomal abnormalities, epigenetic alterations, and unhealthy lifestyle. Identification of risk factors and biomarkers could lead to a better understanding of molecular pathways involved in CRC pathogenesis. MicroRNAs (miRNAs) are important regulatory molecules which could affect a variety of cellular and molecular targets in CRC. A large number of studies have indicated deregulations of some known tissue‐specific miRNAs, for example, miR‐21, miR‐9, miR‐155, miR‐17, miR‐19, let‐7, and miR‐24 as well as circulating miRNAs, for example, miR‐181b, miR‐21, miR‐183, let‐7g, miR‐17, and miR‐126, in patients with CRC. In the current review, we focus on the findings of preclinical and clinical studies performed on tissue‐specific and circulating miRNAs as diagnostic biomarkers and therapeutic targets for the detection of patients at various stages of CRC.
Sleep‐disordered breathing in pediatric head and neck vascular malformations
Authors: Durr Megan L. , Meyer Anna K. , Kezirian Eric J. , Mamlouk Mark D. , Frieden Ilona J. , Rosbe Kristina W.
Published: January 2017

Objectives

To determine the prevalence of sleep‐disordered breathing (SDB) symptoms among children with head and neck vascular malformations and to compare obstructive sleep apnea (OSA)‐18 scores between children with head and neck vascular malformations and children with non‐head and neck vascular malformations.

Study Design

Retrospective cohort and prospective cross‐sectional studies

Methods

Forty‐three pediatric subjects with head and neck vascular malformations evaluated at a tertiary‐care multidisciplinary vascular anomalies center were included in a retrospective cohort study. Eighty‐three consecutive pediatric subjects with vascular malformations evaluated at the same center were included in the prospective cross‐sectional study.

Results

In the retrospective cohort study, 20 (47%) subjects with head and neck malformations had documented SDB symptoms. Of those with SDB symptoms, five (25%) required long‐term tracheotomy. The children with SDB symptoms had greater vascular malformation size, more extensive pharyngeal involvement, greater vascular malformation mass effect on airway, and closer proximity of malformation to airway when compared to children without SDB symptoms.

For the prospective cross‐sectional study, 23% of pediatric subjects had malformations of the head and neck. Those with head and neck malformations had a higher OSA‐18 score and a lower overall quality of life (QOL) score when compared to subjects with non‐head and neck malformations.

Conclusion

Nearly half of children with head and neck vascular malformations have SDB symptoms. Children with head and neck vascular malformations have a higher OSA‐18 score and lower overall QOL score when compared to children with non‐head and neck vascular malformations.

Level of Evidence

4. Laryngoscope, 127:2159–2164, 2017
The 24‐hour normothermic machine perfusion of discarded human liver grafts
Authors: Vogel Thomas , Brockmann Jens G. , Quaglia Alberto , Morovat Alireza , Jassem Wayel , Heaton Nigel D. , Coussios Constantin C. , Friend Peter J.
Published: January 2017

Donor organ shortage necessitates use of less than optimal donor allografts for transplantation. The current cold storage preservation technique fails to preserve marginal donor grafts sufficiently. Evidence from large animal experiments suggests superiority of normothermic machine preservation (NMP) of liver allografts. In this study, we analyze discarded human liver grafts that underwent NMP for the extended period of 24 hours. Thirteen human liver grafts which had been discarded for transplantation were entered into this study. Perfusion was performed with an automated device using an oxygenated, sanguineous perfusion solution at normothermia. Automated control was incorporated for temperature‐, flow‐, and pressure‐regulation as well as oxygenation. All livers were perfused for 24 hours; parameters of biochemical and synthetic liver function as well as histological parameters of liver damage were analyzed. Livers were stratified for expected viability according to the donor's medical history, procurement data, and their macroscopic appearance. Normothermic perfusion preservation of human livers for 24 hours was shown to be technically feasible. Human liver grafts, all of which had been discarded for transplantation, showed levels suggesting organ viability with respect to metabolic and synthetic liver function (to varying degrees). There was positive correlation between instantly available perfusion parameters and generally accepted predictors of posttransplant graft survival. In conclusion, NMP is feasible reliably for periods of at least 24 hours, even in highly suboptimal donor organs. Potential benefits include not only viability testing (as suggested in recent clinical implementations), but also removal of the time constraints associated with the utilization of high‐risk livers, and recovery of ischemic and other preretrieval injuries (possibly by enabling therapeutic strategies during NMP). Liver Transplantation 23 207–220 2017 AASLD
Consumer Risk‐reduction Behavior and New Product Purchases
Authors: Yonezawa Koichi , Richards Timothy J.
Published: January 2017

Consumers purchase lower quantities of new products compared with those they have purchased in the past. We explain this observation as a result of risk‐averting behavior by utility‐maximizing consumers. If a new product involves a higher degree of risk that quality expectations will not be met compared with an incumbent product, we show that utility will be more concave for the new product. We test this prediction using a multiple‐discrete/continuous extreme value (MDCEV) model of demand. We show that utility is indeed more concave for new products relative to previously purchased products. Copyright © 2017 John Wiley & Sons, Ltd.
Determining distributed parameters in a neuronal cable model on a tree graph
Authors: Avdonin Sergei , Bell Jonathan , Nurtazina Karlygash
Published: January 2017

For graph domains without cycles, we show how unknown coefficients and source terms for a parabolic equation can be recovered from the dynamical Neumann‐to‐Dirichlet map associated with the boundary vertices. Through use of a companion wave equation problem, the topology of the tree graph, degree of the vertices, and edge lengths can also be recovered. The motivation for this work comes from a neuronal cable equation defined on the neuron's dendritic tree, and the inverse problem concerns parameter identification of k unknown distributed conductance parameters. Copyright © 2017 John Wiley & Sons, Ltd.
Stability analysis in a diffusional immunosuppressive infection model with delayed antiviral immune response
Authors: Tian Canrong , Gan Wenzhen , Zhu Peng
Published: January 2017

In this paper, the diffusion is introduced to an immunosuppressive infection model with delayed antiviral immune response. The direction and stability of Hopf bifurcation are effected by time delay, in the absence of which the positive equilibrium is locally asymptotically stable by means of analyzing eigenvalue spectrum; however, when the time delay increases beyond a threshold, the positive equilibrium loses its stability via the Hopf bifurcation. The stability and direction of the Hopf bifurcation is investigated with the norm form and the center manifold theory. The stability of the Hopf bifurcation leads to the emergence of spatial spiral patterns. Numerical calculations are performed to illustrate our theoretical results. Copyright © 2017 John Wiley & Sons, Ltd.
Analysis of the effects of noise, DWI sampling, and value of assumed parameters in diffusion MRI models
Authors: Hutchinson Elizabeth B. , Avram Alexandru V. , Irfanoglu M. Okan , Koay C. Guan , Barnett Alan S. , Komlosh Michal E. , Özarslan Evren , Schwerin Susan C. , Juliano Sharon L. , Pierpaoli Carlo
Published: January 2017

Purpose

This study was a systematic evaluation across different and prominent diffusion MRI models to better understand the ways in which scalar metrics are influenced by experimental factors, including experimental design (diffusion‐weighted imaging [DWI] sampling) and noise.

Methods

Four diffusion MRI models—diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), mean apparent propagator MRI (MAP‐MRI), and neurite orientation dispersion and density imaging (NODDI)—were evaluated by comparing maps and histogram values of the scalar metrics generated using DWI datasets obtained in fixed mouse brain with different noise levels and DWI sampling complexity. Additionally, models were fit with different input parameters or constraints to examine the consequences of model fitting procedures.

Results

Experimental factors affected all models and metrics to varying degrees. Model complexity influenced sensitivity to DWI sampling and noise, especially for metrics reporting non‐Gaussian information. DKI metrics were highly susceptible to noise and experimental design. The influence of fixed parameter selection for the NODDI model was found to be considerable, as was the impact of initial tensor fitting in the MAP‐MRI model.

Conclusion

Across DTI, DKI, MAP‐MRI, and NODDI, a wide range of dependence on experimental factors was observed that elucidate principles and practical implications for advanced diffusion MRI. Magn Reson Med 78:1767–1780, 2017. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution‐NonCommercial License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited and is not used for commercial purposes.
Can Patel's τ accurately estimate directionality of connections in brain networks from fMRI?
Authors: Wang Yunzhi , David Olivier , Hu Xiaoping , Deshpande Gopikrishna
Published: January 2017

Purpose

Investigating directional interactions between brain regions plays a critical role in fully understanding brain function. Consequently, multiple methods have been developed for noninvasively inferring directional connectivity in human brain networks using functional MRI (fMRI). Recent simulations by Smith et al. showed that Patel's τ, a method based on higher‐order statistics, was the best approach for inferring directional interactions from fMRI. Because simulations make restrictive assumptions about reality, we set out to verify this finding using experimental fMRI data obtained from a three‐region network in a rat model with electrophysiological validation.

Methods

Previous studies have shown that dynamic causal modeling can correctly estimate the directionality of this three‐region network; Granger causality can also work after the deconvolution of the hemodynamic response. Therefore, we set out to test the hypothesis that Patel's τ obtained from either raw or deconvolved fMRI data should correctly estimate the directionality of neuronal influences obtained from intracerebral electroencephalogram in this network.

Results

Our results indicate that the accuracy of network directionality estimated using Patel's τ was not better than chance.

Conclusion

First, our results highlight the necessity of experimental validation of simulation results. Second, it is unclear which brain mechanism is modeled by a directionality inferred from Patel's τ. Third, this study shows that a directional connection ascertained by different methods may mean different things and more experimental studies are needed for investigating the neuronal mechanisms underlying the direction of a connection in the brain ascertained by fMRI using different methods. M Magn Reson Med 78:2003–2010, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Real‐time monitoring of tissue displacement and temperature changes during MR‐guided high intensity focused ultrasound
Authors: Bour Pierre , Marquet Fabrice , Ozenne Valéry , Toupin Solenn , Dumont Erik , Aubry Jean‐François , Lepetit‐Coiffe Matthieu , Quesson Bruno
Published: January 2017

Purpose

The therapy endpoint most commonly used in MR‐guided high intensity focused ultrasound is the thermal dose. Although namely correlated with nonviable tissue, it does not account for changes in mechanical properties of tissue during ablation. This study presents a new acquisition sequence for multislice, subsecond and simultaneous imaging of tissue temperature and displacement during ablation.

Methods

A single‐shot echo planar imaging sequence was implemented using a pair of motion‐encoding gradients, with alternated polarities. A first ultrasound pulse was synchronized on the second lobe of the motion‐encoding gradients and followed by continuous sonication to induce a local temperature increase in ex vivo muscle and in vivo on pig liver. Lastly, the method was evaluated in the brain of two volunteers to assess method's precision.

Results

For thermal doses higher than the lethal threshold, displacement amplitude was reduced by 21% and 28% at the focal point in muscle and liver, respectively. Displacement value remained nearly constant for nonlethal thermal doses values. The mean standard deviation of temperature and displacement in the brain of volunteers remained below 0.8 °C and 2.5 µm.

Conclusion

This new fast imaging sequence provides real‐time measurement of temperature distribution and displacement at the focus during HIFU ablation. Magn Reson Med 78:1911–1921, 2017. © 2017 International Society for Magnetic Resonance in Medicine.
Quantitative ultrashort echo time imaging for assessment of massive iron overload at 1.5 and 3 Tesla
Authors: Krafft Axel J. , Loeffler Ralf B. , Song Ruitian , Tipirneni‐Sajja Aaryani , McCarville M. Beth , Robson Matthew D. , Hankins Jane S. , Hillenbrand Claudia M.
Published: January 2017

Purpose

Hepatic iron content (HIC) quantification via transverse relaxation rate (R2*)‐MRI using multi‐gradient echo (mGRE) imaging is compromised toward high HIC or at higher fields due to the rapid signal decay. Our study aims at presenting an optimized 2D ultrashort echo time (UTE) sequence for R2* quantification to overcome these limitations.

Methods

Two‐dimensional UTE imaging was realized via half‐pulse excitation and radial center‐out sampling. The sequence includes chemically selective saturation pulses to reduce streaking artifacts from subcutaneous fat, and spatial saturation (sSAT) bands to suppress out‐of‐slice signals. The sequence employs interleaved multi‐echo readout trains to achieve dense temporal sampling of rapid signal decays. Evaluation was done at 1.5 Tesla (T) and 3T in phantoms, and clinical applicability was demonstrated in five patients with biopsy‐confirmed massively high HIC levels (>25 mg Fe/g dry weight liver tissue).

Results

In phantoms, the sSAT pulses were found to remove out‐of‐slice contamination, and R2* results were in excellent agreement to reference mGRE R2* results (slope of linear regression: 1.02/1.00 for 1.5/3T). UTE‐based R2* quantification in patients with massive iron overload proved successful at both field strengths and was consistent with biopsy HIC values.

Conclusion

The UTE sequence provides a means to measure R2* in patients with massive iron overload, both at 1.5T and 3T. Magn Reson Med 78:1839–1851, 2017. © 2017 Wiley Periodicals, Inc.
Extremal eigenvalue intervals of symmetric tridiagonal interval matrices
Authors: Jian Yuan
Published: January 2017

Computing the extremal eigenvalue bounds of interval matrices is non‐deterministic polynomial‐time (NP)‐hard. We investigate bounds on real eigenvalues of real symmetric tridiagonal interval matrices and prove that for a given real symmetric tridiagonal interval matrices, we can achieve its exact range of the smallest and largest eigenvalues just by computing extremal eigenvalues of four symmetric tridiagonal matrices.
Optimal control strategy–based AGC of electrical power systems: A comparative performance analysis
Authors: Arya Yogendra , Kumar Narendra
Published: January 2017

This study extensively addresses the application of optimal control approach to the automatic generation control (AGC) of electrical power systems. Proportional‐integral structured optimal controllers are designed using full‐state feedback control strategy employing performance index minimization criterion. Some traditional single/multiarea and restructured multiarea power system models from the literature are explored deliberately in the present study. The dynamic performance of optimal controllers is observed superior in comparison to integral/proportional‐integral controllers tuned using some recently published modern heuristic optimization techniques. It is observed that optimal controllers show better system results in terms of minimum value of settling time, peak overshoot/undershoot, various performance indices, and oscillations corresponding to change in area frequencies and tie‐line powers along with maximum value of minimum damping ratio in comparison to other controllers. The results are displayed in the form of tables for ease of comparison. Sensitivity analysis affirms the robustness of the optimal feedback controller gains to wide variations in some system parameters from their nominal values.
1H qNMR Quantification of Annonaceous Acetogenins in Crude Extracts of Annona muricata L. Fruit Pulp
Authors: Bonneau Natacha , Cynober Timothé , Jullian Jean‐Christophe , Champy Pierre
Published: January 2017

Introduction

Annonaceous acetogenins (AAGs) constitute a group of environmental neurotoxins, possibly implicated in sporadic atypical Parkinsonism/dementia complexes. The recent evidencing of complex mixtures of AAGs in edible fruits and derived food products requires efficient and practical analytical tools for an estimation of human exposure.

Objective

To develop a simple method for the direct quantitation of the majority of AAGs (sub‐types 1a and 1b) within crude extracts, using commonly available 1H–NMR spectrometers, for food control.

Methodology

Method development was carried out on 400 MHz and 300 MHz spectrometers, for routine application on fruits crude extracts of Annona muricata L. The method was validated with annonacin and squamocin as reference compounds. Two internal standards (ISs), fumaric acid and dimethyl fumarate, were successfully used, in deuterated methanol (CD3OD) and deuterated chloroform (CDCl3), respectively.

Results

Quantitation was carried out using signals corresponding to the deshielded ethylenic protons characterising most AAGs, at δ 7.18 or δ 6.98 ppm in CDCl3. The limit of quantification (LOQ) was 2.5 mM, with acceptable accuracy, and the limit of detection (LOD) was 0.5 mM. The AAGs contents measured in seven distinct fruit samples of Annona muricata ranged from 14 μmol to 226 μmol of AAGs per 100 g fresh pulp (i.e. 0.14 mmol to 1.3 mmol of AAGs per fruit).

Conclusion

A simple, accurate and specific method for quantification of AAGs content was developed and validated for routine application to fruit pulp crude extracts. Copyright © 2017 John Wiley & Sons, Ltd.
Thin Al2O3 passivated boron emitter of n‐type bifacial c‐Si solar cells with industrial process
Authors: Lu Guilin , Zheng Fei , Wang Jianqiang , Shen Wenzhong
Published: January 2017

We have presented thin Al2O3 (~4 nm) with SiNx:H capped (~75 nm) films to effectively passivate the boron‐doped p+ emitter surfaces of the n‐type bifacial c‐Si solar cells with BBr3 diffusion emitter and phosphorus ion‐implanted back surface field. The thin Al2O3 capped with SiNx:H structure not only possesses the excellent field effect and chemical passivation, but also establishes a simple cell structure fully compatible with the existing production lines and processes for the low‐cost n‐type bifacial c‐Si solar cell industrialization. We have successfully achieved the large area (238.95 cm2) high efficiency of 20.89% (front) and 18.45% (rear) n‐type bifacial c‐Si solar cells by optimizing the peak sintering temperature and fine finger double printing technology. We have further shown that the conversion efficiency of the n‐type bifacial c‐Si solar cells can be improved to be over 21.3% by taking a reasonable high emitter sheet resistance. Copyright © 2017 John Wiley & Sons, Ltd.
Trapping mechanisms in insulated‐gate GaN power devices: Understanding and characterization techniques
Authors: Yang Shu , Liu Shenghou , Lu Yunyou , Chen Kevin J.
Published: January 2017

In addition to surface‐ and buffer‐trapping, interface/border trapping and the consequent VTH shift in insulated‐gate GaN power transistors could also cause RON increase, due to the reduced gate overdrive. This work reports on a systematic study of the trapping mechanisms in normally‐on/off insulated‐gate GaN transistors subjected to dynamic (AC) and static (DC) gate stress. The fast dynamic characterizations featuring an ultrashort measurement delay of 10−7 s minimize the recovery during measurement and enable a quantitative evaluation of VTH shift‐induced RON increase. By analyzing the time‐resolved instability in normally‐on MIS‐HEMT and normally‐off MIS‐FET with fully recessed barrier, we elucidate several key mechanisms including: (i) recessing the polarized III‐nitride barrier layer can suppress VTH shift during ON/OFF switching; (ii) AC stress, which has more practical implication for lifetime projection for power switching applications, produces smaller VTH shift and RON increase comparing to DC stress; (iii) Sufficient gate overdrive at ON state and lower channel resistance in normally‐on MIS‐HEMT allow a better tolerance to VTH shift.

Primary trapping effects in an insulated‐gate GaN power transistor.
Characterization and control of charge transfer in a tunnel junction
Authors: Gabelli Julien , Thibault Karl , Gasse Gabriel , Lupien Christian , Reulet Bertrand
Published: January 2017

Charge transfer in a tunnel junction is studied under dc and ac voltage bias using quantum shot noise. Under dc voltage bias V, spectral density of noise measured within a very large bandwidth enables to deduce the current–current correlator in the time domain by Fourier transform. This correlator exhibits regular oscillations proving that electrons try to cross the junction regularly, every . Using harmonic and bi‐harmonic ac voltage bias, we then show that quasiparticles excitations can be transferred through the junction in a controlled way. By measuring the reduction of the excess shot noise, we are able to determine the number of electron–hole pairs surrounding the injected electrons and demonstrate that bi‐harmonic voltage pulses realize an on‐demand electron source with a very small admixture of electron–hole pairs.

A time‐dependent voltage drive applied to a contact with transmission generates an incoming excitation giving rise to transmitted and reflected quasiparticles. The excess noise given by the difference between the noise measured with and without the ac excitation is measured by an ammeter with a bandwidth . It gives the number of electron–hole pairs surrounding the transmitted electrons: where is the repetition frequency of .
Development of an in vivo visual robot system with a magnetic anchoring mechanism and a lens cleaning mechanism for laparoendoscopic single‐site surgery (LESS)
Authors: Feng Haibo , Dong Dinghui , Ma Tengfei , Zhuang Jinlei , Fu Yili , Lv Yi , Li Liyi
Published: January 2017

Background

Surgical robot systems which can significantly improve surgical procedures have been widely used in laparoendoscopic single‐site surgery (LESS). For a relative complex surgical procedure, the development of an in vivo visual robot system for LESS can effectively improve the visualization for surgical robot systems.

Methods

In this work, an in vivo visual robot system with a new mechanism for LESS was investigated. A finite element method (FEM) analysis was carried out to ensure the safety of the in vivo visual robot during the movement, which was the most important concern for surgical purposes. A master–slave control strategy was adopted, in which the control model was established by off‐line experiments.

Results

The in vivo visual robot system was verified by using a phantom box. The experiment results show that the robot system can successfully realize the expected functionalities and meet the demands of LESS.

Conclusion

The experiment results indicate that the in vivo visual robot with high manipulability has great potential in clinical application.
Values Underpinning STEM Education in the USA: An Analysis of the Next Generation Science Standards
Authors: HOEG DARREN G. , BENCZE JOHN LAWRENCE
Published: January 2017

The Next Generation Science Standards (NGSS) were designed to address poor science and math performance in United States schools by inculcating globally competitive science, technology, engineering, and mathematics literacies relevant to participation in future society. Considering the complex network of influences involved in the development of the NGSS, the purpose of this paper is to evaluate how educational values are embedded in the discourse of the standards. Using critical discourse analysis and content analysis, we evaluated how themes related to (i) performance, (ii) accessibility, and (iii) innovation and creativity are discursively constituted in the NGSS. Our analysis indicates the NGSS prioritizes: measurable and reproducible performances; the standards appear to be based on a conception of accessibility closely aligned with equality, and self‐investment, and; innovation and creativity are discursively constituted as attributes that can be developed through specific, prescribed practices. We discuss these findings in relation to the goals of the NGSS and potential teaching and learning outcomes resulting from education based on the standards.
High‐Throughput, Protein‐Targeted Biomolecular Detection Using Frequency‐Domain Faraday Rotation Spectroscopy
Authors: Murdock Richard J. , Putnam Shawn A. , Das Soumen , Gupta Ankur , Chase Elyse D. Z. , Seal Sudipta
Published: January 2017

A clinically relevant magneto‐optical technique (fd‐FRS, frequency‐domain Faraday rotation spectroscopy) for characterizing proteins using antibody‐functionalized magnetic nanoparticles (MNPs) is demonstrated. This technique distinguishes between the Faraday rotation of the solvent, iron oxide core, and functionalization layers of polyethylene glycol polymers (spacer) and model antibody–antigen complexes (anti‐BSA/BSA, bovine serum albumin). A detection sensitivity of ≈10 pg mL−1 and broad detection range of 10 pg mL−1 ≲ cBSA ≲ 100 µg mL−1 are observed. Combining this technique with predictive analyte binding models quantifies (within an order of magnitude) the number of active binding sites on functionalized MNPs. Comparative enzyme‐linked immunosorbent assay (ELISA) studies are conducted, reproducing the manufacturer advertised BSA ELISA detection limits from 1 ng mL−1 ≲ cBSA ≲ 500 ng mL−1. In addition to the increased sensitivity, broader detection range, and similar specificity, fd‐FRS can be conducted in less than ≈30 min, compared to ≈4 h with ELISA. Thus, fd‐FRS is shown to be a sensitive optical technique with potential to become an efficient diagnostic in the chemical and biomolecular sciences.