bluuebunny/crossref_metadata_2025 huggingface dataset:
Adaptive fuzzy FTC design of nonlinear stochastic systems with actuator faults and unmodeled dynamics
Authors: Su Hang , Zhang Weihai
Published: May 2018

This paper investigates an adaptive fuzzy control method for accommodating actuator faults in a class of uncertain stochastic nonlinear systems with both immeasurable states and unmodeled dynamics. The considered faults are modeled as both loss of effectiveness and lock‐in‐place. To deal with the immeasurable states, a novel state observer containing the actuator faults is designed. Combining with the backstepping technique and stochastic small‐gain theorem, an adaptive fuzzy output feedback control method is developed. The presented design scheme can guarantee that the closed‐loop system is input‐to‐state practically stable in probability. Finally, a simulation example is shown to verify the effectiveness of the proposed control method.
Weibull Analysis of Electrical Breakdown Strength as an Effective Means of Evaluating Elastomer Thin Film Quality
Authors: Silau Harald , Stabell Nicolai Bogø , Petersen Frederik Riddersholm , Pham Martin , Yu Liyun , Skov Anne Ladegaard
Published: May 2018

To realize the commercial potential of dielectric elastomers, reliable, large‐scale film production is required. Ensuring proper mixing and subsequently avoiding demixing after, for example, pumping and coating of elastomer premix in an online process is not facile. Weibull analysis of the electrical breakdown strength of dielectric elastomer films is shown to be an effective means of evaluating the film quality. The analysis is shown to be capable of distinguishing between proper and improper mixing schemes where similar analysis of ultimate mechanical properties fails to distinguish.
The Exploration of Carrier Behavior in the Inverted Mixed Perovskite Single‐Crystal Solar Cells
Authors: Huang Yuan , Zhang Yu , Sun Junlu , Wang Xiaoge , Sun Junliang , Chen Qi , Pan Caofeng , Zhou Huanping
Published: May 2018

Perovskite single crystal (PSC) possesses fewer bulk defects than the polycrystalline film counterpart, which has received extensive attention in a number of optoelectronic device applications. But the management of carrier behavior in an efficient solar cell based on PSC is not reported yet. Here, the carrier behavior within the device based on the ITO/NiOx/(FAPbI3)0.85(MAPbBr3)0.15/TiO2/Ag structure (FA = CH(NH2)2+, MA = CH3NH3+), in which the mixed PSC is successfully implemented into solar cells for the first time, is investigated. The PSC films with lateral dimension from 500 µm to 2 mm and thickness over tens of micrometers, are obtained through the polydimethylsiloxane‐assisted solvent evaporation method. The highest power conversion efficiency derived from the present device approaches 12.18%. It is revealed that the surface roughness and thickness of PSC, the operation temperature and thickness of transport layers, and the interfaces of transport layers/PSC largely impact the carrier extraction and device performance of the perovskite single‐crystal solar cell (PSCSC). This work indicates that the carrier behavior in the absorber layer and transport layer has large impact on the performance of PSCSCs, while the underlying design rule represents an important step to advance the PSCSCs and other optoelectronic devices.
Tuning Transport and Photoelectric Performance of Monolayer MoS2 Device by E‐Beam Irradiation
Authors: Li Feng , Gao Fei , Xu Minxuan , Liu Xinxin , Zhang Xiankun , Wu Hualin , Qi Junjie
Published: May 2018

Here, the effect of E‐beam irradiation on the transport properties of the monolayer MoS2 is investigated in situ using scanning electron microscope (SEM). The results show that the source drain current is increased under E‐beam irradiation; the current gradually increases to a saturation value with an increase in irradiation time, and the saturation value increases with an increase in E‐beam intensity. After E‐beam irradiation, X‐ray photoelectron spectroscopy (XPS) results show that the stoichiometry of MoS2 is modified, while the Raman and PL results reveal that the optical performance of the monolayer MoS2 is not deteriorated. The source–drain current and electron mobility of the MoS2 transistor are reduced by E‐beam irradiation, while the on–off current ratio of the transistor almost unchanges. However, the photoresponse performance, such as the light dark current ratio, response, and release speed of the device are improved. The results are discussed by the creation of defects which vary the injected and trapped charges of the sample by E‐beam irradiation. The results provide a new method to improve the optoelectronic performance of two dimensional (2D) materials devices.
Environment‐Dependent Self‐Assembly of DNA Origami Lattices on Phase‐Separated Lipid Membranes
Authors: Sato Yusuke , Endo Masayuki , Morita Masamune , Takinoue Masahiro , Sugiyama Hiroshi , Murata Satoshi , Nomura Shin‐ichiro M. , Suzuki Yuki
Published: May 2018

Self‐assembly of designed nanostructures on a lipid membrane offers a powerful approach for enhancing the functionality of its surface. Here, the environment‐dependent assembly of blunt‐ended DNA origami structures on a phase‐separated lipid‐bilayer membrane consisting of liquid‐disordered (Ld) and solid‐ordered (So) phases is reported. Fluorescence microscopy and atomic force microscopy (AFM) imaging reveal that DNA origami structures preferentially bind to the So phase. At higher concentrations, blunt‐ended origamis form 2D lattices on the Ld phase through surface‐mediated self‐assembly. In contrast, those adsorbed on the So phase are less mobile and pack into aggregates. However, this situation is changed by adding NaCl. High‐speed AFM imaging reveals the mechanism underlying the NaCl‐induced changes, wherein the lattices on the Ld phase desorb from the surface while the packed aggregates on the So phase reorganize into the lattices. These results indicate that the formation of 2D lattices depends on the phase of the lipids; however, it can be tuned by ionic conditions, enabling us to select the domain on which the lattice is formed. The present results may guide the creation of membrane‐supported DNA nanostructures that self‐assemble into functional states in a lipid phase or ion‐responsive manner.
In Site Growth of Crosslinked Nickel–Cobalt Hydroxides@Carbon Nanotubes Composite for a High‐Performance Hybrid Supercapacitor
Authors: Lv Zijian , Zhong Qin , Bu Yunfei
Published: May 2018

Metal–organic frameworks materials have shown great potential in energy storage and conversion research, but their poor electrical conductivity and inferior chemical stability limit their applications. Herein, an in situ‐grown crosslinked nickel–cobalt hydroxides@carbon nanotubes composite with a nanosheet‐covered hollow structure is rationally designed and synthesized successfully from ZIF‐67@carbon nanotubes. Different from other studies, the carbon nanotubes in this composite penetrate the hollow structure, and the active nanosheets also grow on the parts protruding from the hollow boxes via this in situ synthetic route. Compare with pure nickel–cobalt hydroxides, the composite exhibits enhanced electroactivity in terms of the specific capacity and cycling performance. In particular, it delivers a high specific capacity of 916.8 C g−1 at 1 A g−1 and ≈79.0% of its initial value preserves after 4000 cycles. This facile synthetic approach enables the preparation of crosslinked metal–organic framework materials with the potential to meet the demands of energy storage and conversion devices as well as supercapacitors.
Elucidating Surface and Bulk Emission in 3D Hybrid Organic–Inorganic Lead Bromide Perovskites
Authors: Chi Xiao , Leng Kai , Wu Bo , Shi Dong , Choy Yufong , Chen Zhongxin , Chen Zhihui , Yu Xiaojiang , Yang Ping , Xu Qing‐Hua , Sum Tze Chien , Rusydi Andrivo , Loh Kian Ping
Published: May 2018

Three dimensional (3D) hybrid organic–inorganic lead halide perovskites (HOIP) have emerged in recent years as promising materials for a wide variety of optoelectronic applications. However, the photoluminescence energies in bromide‐based HOIP have been reported to vary in the range from 2.16 to 2.35 eV. The occurrence of surface reconstructions due to uncompensated surface ionic charges may change the photo‐physical properties of the surface regions, but this has not been studied in detail. Herein, by performing angle‐dependent photoluminescence (PL) and spectroscopic ellipsometry of single‐crystal as well as polycrystalline HOIP crystals, the intrinsic excitonic emissions from the surface and bulk regions are clearly identified. It is verified that the high energy PL at 2.31 eV originates from a phase‐modified surface region. The large absorption coefficient of perovskite results in signal depletion of the lower energy PL at 2.16 eV, which originates from the bulk. High resolution synchrotron X‐ray diffraction reveals that air‐exposed HOIP crystals form a multilayer structure consisting of PbBr2, and an interfacial layer of orthorhombic phase, while the bulk crystal remains cubic phase. This study provides the unambiguous identification of a phase‐modified surface region with a larger band gap than the bulk and which dominates the excitonic emission in HOIP crystals.
Multifunctional and Stimuli‐Responsive Magnetic Nanoparticle‐Based Delivery Systems for Biomedical Applications
Authors: Yang Hong Yu , Li Yi , Lee Doo Sung
Published: May 2018

The design and development of a multifunctional and stimuli‐responsive magnetic nanoparticle (MNP)‐based drug delivery system has attracted great interest for the diagnosis and therapy of cancer. However, the effective incorporation of magnetic iron oxide nanoparticles into biomedical systems requires in vitro and in vivo stability, good biocompatibility, high loading efficacy, and controlled drug release. Surface‐functionalized magnetic iron oxide nanoparticles created using engineered surface ligands have presented new strategies for the applications of MNP‐based drug delivery systems in cancer imaging and therapy to overcome these obstacles. Moreover, the development and design of stimuli‐responsive ligands has been combined with the engineering of multiple physicochemical features into MNPs to enhance the performance of the MNP‐based delivery system. This review briefly overviews the latest developments in the design of multifunctional and stimuli‐responsive MNP‐based drug delivery systems and summarizes their applications in the diagnostic imaging and treatment of cancer.
Seeded Space‐Limited Crystallization of CH3NH3PbI3 Single‐Crystal Plates for Perovskite Solar Cells
Authors: Yue Hong‐Lin , Sung Hsin‐Hung , Chen Fang‐Chung
Published: May 2018

The synthesis of certain perovskite single crystals (SCs), including CH3NH3PbI3, through asymmetric crystallization is difficult, mainly because of the large difference in solubility of the precursors and/or the intrinsic nonpreference for growth in a direction along the substrate. Herein, an effective method is reported, seeded space‐limited inverse‐temperature crystallization (SSLITC), for growing CH3NH3PbI3 SC plates having micrometer‐scale diameters. In this process, a seed CH3NH3PbI3 crystal is incorporated within a confined space to promote crystallization. Crystal plates having lateral dimensions of up to 2 mm are grown successfully. These SCs and a polymer conductive glue to fabricate perovskite solar cells on flexible substrates are used. One such device exhibits a maximum external quantum efficiency of 96%, a high photocurrent of 22 mA cm−2, and a power conversion efficiency of greater than 4%. In addition, a device prepared without any encapsulation exhibits reasonable stability, suggesting a promising future for SC‐based perovskite solar cells. It is anticipated that the SSLITC method proposed herein could open up new avenues for synthesizing various types of organic/inorganic perovskite SCs for applications in modern electronics.
Effect of Annealing Ferroelectric HfO2 Thin Films: In Situ, High Temperature X‐Ray Diffraction
Authors: Park Min Hyuk , Chung Ching‐Chang , Schenk Tony , Richter Claudia , Opsomer Karl , Detavernier Christophe , Adelmann Christoph , Jones Jacob L. , Mikolajick Thomas , Schroeder Uwe
Published: May 2018

The ferroelectricity in fluorite oxides has gained increasing interest due to its promising properties for multiple applications in semiconductor as well as energy devices. The structural origin of the unexpected ferroelectricity is now believed to be the formation of a non‐centrosymmetric orthorhombic phase with the space group of Pca21. However, the factors driving the formation of the ferroelectric phase are still under debate. In this study, to understand the effect of annealing temperature, the crystallization process of doped HfO2 thin films is analyzed using in situ, high‐temperature X‐ray diffraction. The change in phase fractions in a multiphase system accompanied with the unit cell volume increase during annealing could be directly observed from X‐ray diffraction analyses, and the observations give an information toward understanding the effect of annealing temperature on the structure and electrical properties. A strong coupling between the structure and the electrical properties is reconfirmed from this result.
Key Tradeoffs Limiting the Performance of Organic Photovoltaics
Authors: Ramirez Ivan , Causa' Martina , Zhong Yufei , Banerji Natalie , Riede Moritz
Published: May 2018

2017 saw the publication of several new material systems that challenge the long‐held notion that a driving force is necessary for efficient exciton dissociation in organic photovoltaics (OPVs) and that a loss of ≈0.6 eV between the energy of the charge transfer stateEctand the energy corresponding to open circuit is general. In light of these developments, the authors combine insights from device physics and spectroscopy to review the two key tradeoffs limiting OPV performances. These are the tradeoff between the charge carrier generation efficiency and the achievable open circuit voltage (Voc) and the tradeoff between device thickness (light absorption) and fill factor. The emergence of several competitive nonfullerene acceptors (NFAs) is exciting for both of these. The authors analyze what makes these materials compare favorably to fullerenes, including the potential role of molecular vibrations, and discuss both design criteria for new molecules and the achievable power conversion efficiencies.
Astrophysical Black Holes: A Compact Pedagogical Review
Authors: Bambi Cosimo
Published: May 2018

Black holes are among the most extreme objects that can be found in the Universe and an ideal laboratory for testing fundamental physics. Here, the basic properties of black holes as expected from general relativity, the main astronomical observations, and the leading astrophysical techniques to probe the strong gravity region of these objects are reviewed. The main intention is to provide a compact introductory overview on astrophysical black holes to new students entering this research field, as well as to senior researchers working in general relativity and alternative theories of gravity, who wish to quickly learn the state of the art of astronomical observations of black holes.
Zeitaufgelöst und markerfrei gemessene ligandeninduzierte Konformationsänderungen von HSP90 – hin zu einem Konformationsaktivitätsscreening für die Wirkstoffentwicklung
Authors: Güldenhaupt Jörn , Amaral Marta , Kötting Carsten , Schartner Jonas , Musil Djordje , Frech Matthias , Gerwert Klaus
Published: May 2018

Während der frühen Medikamentenentwicklung ist die Untersuchung der Protein‐Liganden‐Wechselwirkungen von entscheidender Bedeutung. Die ATR‐FTIR‐Spektroskopie kann Protein‐Liganden‐Wechselwirkungen markerfrei mit hoher räumlicher und zeitlicher Auflösung detektieren. Wir haben das Hitzeschockprotein HSP90, einen wichtigen molekularen Angriffspunkt für Medikamente, auf einem ATR‐Kristall immobilisiert und mit unserem neuartigen Ansatz eine ligandeninduzierte Sekundärstrukturänderung untersucht. Zwei spezifische Bindungsmodi von 19 Inhibitoren wurden analysiert. Unterschiedliche Bindungsmodi können zu unterschiedlicher Wirksamkeit und Spezifität verschiedener Medikamente führen. Darüber hinaus wurden die kobs‐Werte der Dissoziation der Liganden ermittelt. Die Ergebnisse werden durch Röntgenkristallographie für die Strukturänderung und SPR‐Experimente für die Dissoziationskinetik validiert, wobei unsere Methode sämtliche Daten in einem einzigen und einfachen Experiment liefert.
Serious Infections in Rheumatoid Arthritis Offspring Exposed to Tumor Necrosis Factor Inhibitors
Authors: Vinet Évelyne , De Moura Cristiano , Pineau Christian A. , Abrahamowicz Michal , Curtis Jeffrey R. , Bernatsky Sasha
Published: May 2018

Objective

To evaluate the risk of serious infections in rheumatoid arthritis (RA) offspring exposed to tumor necrosis factor inhibitors (TNFi) in the gestational period compared to unexposed RA offspring, as well as to children from the general population.

Methods

We used US claim data (2011–2015) to identify 2,989 offspring born to women who have RA and a randomly selected group of 14,596 control children, matched ≥4:1 for maternal age, year of delivery, and state of residence. We defined TNFi exposure based on ≥1 filled prescription during pregnancy. We ascertained serious infections based on ≥1 hospitalization, with infection as a primary diagnosis, at ≤12 months of life. We performed multivariable analyses, adjusting for maternal demographics, comorbidities, pregnancy complications, and drugs.

Results

Among RA offspring, 380 (12.7%) were exposed to TNFi during pregnancy. The percentage of serious infections in RA offspring with no TNFi exposure (2.0%; 95% confidence interval [95% CI] 1.5, 2.6) was similar to that in non‐RA offspring (1.9%; 95% CI 1.9, 2.2), while the percentage of serious infections in RA offspring with TNFi exposure was 3.2% (95% CI 1.5, 5.6). In multivariable analyses, we were unable to establish an increased risk of serious infections in RA offspring exposed to TNFi versus both non‐RA offspring (odds ratio [OR] 1.7, 95% CI 0.8, 3.7) and RA offspring unexposed to TNFi (OR 1.4, 95% CI 0.7, 2.8).

Conclusion

We did not demonstrate a marked excess risk for serious infections in RA offspring exposed to TNFi during pregnancy versus unexposed RA offspring or general population controls.
Synthesis and Characterization of Stable Phosphorus Carbabetaines
Authors: Yanai Hikaru , Almendros Pedro , Takahashi Saori , Lázaro‐Milla Carlos , Alcaide Benito , Matsumoto Takashi
Published: May 2018

Phosphorus 1,3‐ and 1,4‐carbabetaines with ′P(+)−C−C(−)′ and ′P(+)−C−C−C(−)′ structures, respectively, in which the carbanion moiety was significantly stabilized by two trifluoromethylsulfonyl groups, have been synthesized and characterized. Analysis of their X‐ray crystal structures revealed that any attractive interactions between the anionic and cationic moieties were negligibly weak. This result was corroborated by using natural bond orbital (NBO) and Bader′s quantum theory of atoms in molecules (QTAIM) models. In contrast, performing the same analysis of a known 1,3‐carbabetaine equivalent, which can be drawn as a ′P(+)−C−C=C−O(−)′ resonance structure, revealed pronounced charge‐transfer interactions between the anionic and cationic moieties.
Ten years of the Surgical Safety Checklist
Authors: Weiser T G , Haynes A B
Published: May 2018

Not just a tick box exercise
Study of Ultra‐Sensitive AMS Method to Identify Drug–Drug Interactions between Ciprofloxacin and Microdose 14C‐Caffeine
Authors: Lee Gwan‐Ho , Oh Min‐Seok , Park Min‐Ho , Shin Young G. , Song Jong Han , Yu Byung‐Yong
Published: May 2018

Identifying drug–drug interactions, potentially affecting efficacy and safety of each drug is essential for drug development. Microdose, administration of a drug at less than 100 μg or 1/100 of its therapeutic dose, is a promising method to safely test drugs during development. This paper examines drug–drug interactions between therapeutic doses of ciprofloxacin and trace amounts of 14C‐ caffeine for microdosing in mice using AMS for analysis. The pharmacokinetic (PK) parameters for caffeine with and without administration of ciprofloxacin did not show any change in Tmax. However, the values of T1/2, Cmax, and AUCinf with administration of ciprofloxacin increased by 57, 22, and 42%, respectively. This is in agreement with previous studies that used full prescription doses. It is shown here that microdose techniques combined with AMS measurements can be used for accurate prediction of drug–drug interactions while conducting relatively safe, small dose studies.
Consumer motivations for sustainable consumption: The interaction of gain, normative and hedonic motivations on electric vehicle adoption
Authors: Rezvani Zeinab , Jansson Johan , Bengtsson Maria
Published: May 2018

Recent conceptual studies identify gain, normative and hedonic factors as three categories of motivations of consumer proenvironmental behavior. However, empirical understanding of how these motivations interact and affect proenvironmental behavior is limited. This study is based on a survey of car owners in Sweden (N = 573) and uses structural equation modeling to analyze the data. The empirical findings point to the importance of all three motivations (gain, normative and hedonic) in consumer electric vehicle adoption intentions. Furthermore, for consumers who perceive high social norms regarding sustainable consumption, the direct effect of hedonic motivations on behavioral intention is stronger, and the direct effect of gain motivations is insignificant. The business strategy implications indicate that targeting consumers who perceive high social norms in relation to proenvironmental behavior and communicating the hedonic and normative aspects of proenvironmental behaviors to this group might be more effective than general mass communication.
Variable anatomic configuration of the posterior spinal arteries in humans
Authors: Rojas Santiago , Ortega Marisa , RodríGuez‐Baeza Alfonso
Published: May 2018

Posterior spinal arteries (PSAs) arise from the vertebral (VA) or posterior inferior cerebellar (PICA) artery. We identified variations in their origins and their anastomosis with the first posterior radiculomedullary branches in human spinal cords. Spinal cords from male and female cadavers (n = 30) were injected with colored latex through the vertebral, ascending cervical, costocervical trunk and segmental arteries. Specimens were fixed in formalin and the spinal arteries were dissected under a surgical microscope. PSAs arise from the PICA and from the atlantoaxial (V3) or intracranial (V4) segments of the VA. Their origins can be at V3 between the axis and the transverse processes of the atlas (V3i) or between the processes and the occipital bone (V3s). Half of our specimens exhibited a symmetrical and half an asymmetrical origin of the PSAs. A symmetrical origin from V4 was the most common configuration, identified in 30% of specimens. There was a symmetrical origin from either segment of V3 or PICA in 10%. Asymmetrical configurations were observed from V4/V3 (23.7%), V3/PICA (16.7%), V4/PICA (6.7%) and V3i/V3s (3.3%). PSAs are supplied by the posterior radiculomedullary arteries along the spinal cord. The first of these anastomoses could be located at any level between C4 and T8, though most commonly at C6‐C7 or T3‐T4. PSAs can originate from either the VA or the PICA in a symmetrical or asymmetrical configuration. Variations in the origin and level of the first posterior radiculomedullary anastomosis could affect surgical approaches, endovascular procedures, and the posterior spinal cord's susceptibility to ischemia. Clin. Anat. 31:1137–1143, 2018. © 2018 Wiley Periodicals, Inc.
The effects of infrared stabilized immature rice grain flour in gluten‐free bread preparation
Authors: Özer Melike , Yılmaz Tuncel Neşe , Tuncel Necati Barış
Published: May 2018

Immature rice grain, which is one of the by‐products of paddy milling process, was used in gluten‐free bread production at the levels of 0% (control) 30%, 50%, 70%, and 100% after being stabilized using infrared radiation (at 1,600 W for 4 min). The effects of the infrared stabilized immature rice grain flour (IRGF) substitution on proximate composition, cooking properties, crumb and crust color, mineral composition, B1 and B2 vitamins, tocopherols, gamma‐oryzanol, texture, and sensory properties of the breads were evaluated. Insoluble dietary fiber, Mg, Mn, K, and Fe contents of the breads remarkably increased with IRGF incorporation (p < 0.05). Tocopherol content of the breads substituted with IRGF at the level of 100% was 77% higher than that of the control bread, whereas no notable variation was observed for vitamin B1 with regard to IRGF substitution (p > 0.05). Gamma‐oryzanol content of the breads made from IRGF (100%) was about three times higher than that of the tocopherol content. Hardness, adhesiveness, gumminess, and chewiness of the breads pronouncedly increased with the incorporation of IRGF at the level of 50% or higher. Gluten‐free bread substituted with IRGF at the level of 30% was the most preferred bread with respect to consumers’ overall acceptance.
A Dehydrogenase Dual Hydrogen Abstraction Mechanism Promotes Estrogen Biosynthesis: Can We Expand the Functional Annotation of the Aromatase Enzyme?
Authors: Spinello Angelo , Pavlin Matic , Casalino Lorenzo , Magistrato Alessandra
Published: May 2018

Cytochrome P450 (CYP450) enzymes are involved in the metabolism of exogenous compounds and in the synthesis of signaling molecules. Among the latter, human aromatase (HA) promotes estrogen biosynthesis, which is a key pharmacological target against breast cancers. After decades of debate, interest in gaining a comprehensive picture of HA catalysis has been renewed by the recent discovery that compound I (Cpd I) is the reactive species of the peculiar aromatization step. Herein, for the first time, a complete atomic‐level picture of all controversial steps of estrogen biosynthesis is presented. By performing cumulative quantum‐classical molecular dynamics and metadynamics simulations of about 180 ps, it is revealed that the most likely enzymatic path relies on three factors: 1) androstenedione enolization and compound 0 (Cpd 0) formation through a proton network mediated by Asp309; 2) subsequent formation of Cpd I, upon rearrangement of the Asp309 side chain and the establishment of a proton network involving Asp309 and Thr310; and 3) after two hydroxylation reactions, 19,19‐gem‐diol is converted into estrone by Cpd I, through an uncommon dehydrogenase‐like dual hydrogen abstraction mechanism. As a result, HA performs estrogen biosynthesis by merging hydroxylase with dehydrogenase activity, which suggests that the need to perform complex chemical transformations led nature to engineer HA, and possibly other steroidogenic CYP450s, by expanding its range of functions to achieve an optimal catalytic efficiency.
Probing Calcium‐Based Metal‐Organic Frameworks via Natural Abundance 43Ca Solid‐State NMR Spectroscopy
Authors: Chen Shoushun , Lucier Bryan E. G. , Chen Mansheng , Terskikh Victor V. , Huang Yining
Published: May 2018

Calcium‐based metal‐organic frameworks (MOFs) are of high importance due to their low cost and bio‐compatible metal centers. Understanding the local environment of calcium in these materials is critical for unraveling the origins of specific MOF properties. 43Ca solid‐state NMR spectroscopy is one of the very few techniques that can directly characterize calcium metal centers, however, the 43Ca nucleus is a very challenging target for solid‐state NMR spectroscopy due to its extremely low natural abundance and resonant frequency. In this work, natural abundance 43Ca solid‐state NMR spectroscopy, at a high magnetic field of 21.1 T, has been employed to characterize several calcium‐based MOFs. We demonstrate that 43Ca NMR spectra and quantum chemical calculations can probe the local structure of calcium metal centers within MOFs, investigate the presence of guests, and monitor phase changes.
Kinetic Studies on the Crosslinking of Cellulose Membranes with Polyfunctional Epoxides in Aqueous Solution
Authors: Tolk Jakob , Ruhr Dominik , Reiche Annette , van der Kruijs Sandra
Published: May 2018

The kinetic parameters of the crosslinking reaction between cellulose membranes and an aqueous solution of 1,4‐butanediol diglycidyl ether were determined by dynamic differential scanning calorimetry (DSC) experiments. The reaction shows an autocatalytic behavior which was described by an extended Prout‐Tompkins equation. Conversion curves were simulated based on these results and function as a basis for the design and improvement of continuous processes used for the industrial production of crosslinked cellulose membranes.
Cytotoxic Activity and Structure–Activity Relationship of Triazole‐Containing Bis(Aryl Ether) Macrocycles
Authors: Hernández‐Vázquez Eduardo , Chávez‐Riveros Alejandra , Romo‐Pérez Adriana , Ramírez‐Apán María Teresa , Chávez‐Blanco Alma D. , Morales‐Bárcenas Rocío , Dueñas‐González Alfonso , Miranda Luis D.
Published: May 2018

Cancer continues to be a worldwide health problem. Certain macrocyclic molecules have become attractive therapeutic alternatives for this disease because of their efficacy and, frequently, their novel mechanisms of action. Herein, we report the synthesis of a series of 20‐, 21‐, and 22‐membered macrocycles containing triazole and bis(aryl ether) moieties. The compounds were prepared by a multicomponent approach from readily available commercial substrates. Notably, some of the compounds displayed interesting cytotoxicity against cancer (PC‐3) and breast (MCF‐7) cell lines, especially those bearing an aliphatic or a trifluoromethyl substituent on the N‐phenyl moiety (IC50<13 μm). Additionally, some of the compounds were able to induce apoptosis relative to the solvent control; in particular, (Z)‐N‐cyclohexyl‐7‐oxo‐6‐[4‐(trifluoromethyl)phenyl]‐11H‐3,10‐dioxa‐6‐aza‐1(4,1)‐triazola‐4(1,3),9(1,4)‐dibenzenacyclotridecaphane‐5‐carboxamide (12 f) was the most potent in this regard (22.7 % of apoptosis).
Approximate Separability of the Green's Function of the Helmholtz Equation in the High Frequency Limit
Authors: Engquist Björn , Zhao Hongkai
Published: May 2018

The minimum number of terms that are needed in a separable approximation for a Green's function reveals the intrinsic complexity of the solution space of the underlying differential equation. It also has implications for whether low‐rank structures exist in the linear system after numerical discretization. The Green's function for a coercive elliptic differential operator in divergence form was shown to be highly separable [2], and efficient numerical algorithms exploiting low‐rank structures of the discretized systems were developed.

In this work, a new approach to study the approximate separability of the Green's function of the Helmholtz equation in the high‐frequency limit is developed. We show (1) lower bounds based on an explicit characterization of the correlation between two Green's functions and a tight dimension estimate for the best linear subspace to approximate a set of decorrelated Green's functions, (2) upper bounds based on constructing specific separable approximations, and (3) sharpness of these bounds for a few case studies of practical interest. © 2018 Wiley Periodicals, Inc.
Stable and Efficient Nitrogen‐Containing Carbon‐Based Electrocatalysts for Reactions in Energy‐Conversion Systems
Authors: Wang Sicong , Teng Zhengyuan , Wang Chengyin , Wang Guoxiu
Published: May 2018

High activity and stability are crucial for the practical use of electrocatalysts in fuel cells, metal–air batteries, and water electrolysis, including the oxygen reduction reaction, hydrogen evolution reaction, oxygen evolution reaction, and oxidation reactions of formic acid and alcohols. Electrocatalysts based on nitrogen‐containing carbon (N‐C) materials show promise in catalyzing these reactions; however, there is no systematic review of strategies for the engineering of active and stable N‐C‐based electrocatalysts. Herein, a comprehensive comparison of recently reported N‐C‐based electrocatalysts regarding both electrocatalytic activity and long‐term stability is presented. In the first part of this review, the relationships between the electrocatalytic reactions and selection of the element to modify the N‐C‐based materials are discussed. Afterwards, synthesis methods for N‐C‐based electrocatalysts are summarized, and strategies for the synthesis of highly stable N‐C‐based electrocatalysts are presented. Multiple tables containing data on crucial parameters for both electrocatalytic activity and stability are displayed in this review. Finally, constructing M‐Nx moieties is proposed as the most promising engineering strategy for stable N‐C‐based electrocatalysts.
Novel approaches to study coronary vasculature development in mice
Authors: Kolesová Hana , Bartoš Martin , Hsieh Wan Chin , Olejníčková Veronika , Sedmera David
Published: May 2018

Background: Coronary artery development is an intensely studied field. Mice are a popular genetic model for developmental studies, but there is no widely accepted protocol for high‐throughput, high‐resolution imaging of their developmental and adult coronary artery anatomy. Results: Using tissue‐clearing protocols and confocal microscopy, we have analyzed embryonic and juvenile mouse hearts in Cx40:GFP knock‐in models with a special focus on septal artery development. We found that the septal artery, which supplies the interventricular septum, was initially formed as an arterial plexus that connected to both the left and right coronary arteries. During development, the plexus was remodeled into a single tube, which then remained connected only to the right coronary artery. Since optical imaging became limited at postnatal stages, it was supplemented with injection techniques using India ink and Microfil; the latter was subsequently analyzed with micro‐CT to visualize the anatomy of coronary vessels in 3D. Conclusions: The techniques described here enable us to study the finer details of coronary artery development in mice and can, therefore, be implemented to study the pathogenesis of coronary malformations in various mouse models. Developmental Dynamics 247:1018‐1027, 2018. © 2018 Wiley Periodicals, Inc.
Influence of soil–water content on CO2 efflux within the elevation transect heavily impacted by erosion
Authors: Fér Miroslav , Kodešová Radka , Nikodem Antonín , Jelenová Klára , Klement Aleš
Published: May 2018

This study focused on the effects of organic carbon contents and soil hydraulic conditions on CO2 efflux. Samples were collected at 5 positions (summit, shoulder, backslope, footslope, and toeslope) of the elevation transect affected by erosion and the parent material (loess). Initially, air‐dried soil samples were placed on top of a clay tank, and the samples were wetted by capillary rise to soil saturation, and soil CO2 efflux was measured. Numerical inversions of the measured cumulative capillary rise and evaporation data using the HYDRUS‐1D program were applied to simulate the water regime in the columns and estimate the soil hydraulic parameters. In all cases, the net CO2 efflux (NCER) rapidly increased at the beginning of the wetting. NCER decreased with increasing soil–water content (summit, shoulder, backslope, and loess) or remained relatively stable (footslope and toeslope). The average soil–water content values at the maximal values of NCER (maxNCER) for the summit, shoulder, and footslope were similar. Lower average soil–water contents at maxNCER were simulated for the backslope, toeslope, and loess, which were attributed to the high contents of loess substrate in topsoil samples. The maxNCER measured on topsoils were closely related to the organic carbon contents (R = 0.94) and the maxNCER obtained on all samples correlated with the parameters αRES (R = 0.856) and nRES (R = −0.876) of the soil–water retention curves and saturated hydraulic conductivity (R = 0.856).
Influence of the Molecular Weight of Poly‐Acrylic Acid Binder on Performance of Si‐Alloy/Graphite Composite Anodes for Lithium‐Ion Batteries
Authors: Kasinathan Raam , Marinaro Mario , Axmann Peter , Wohlfahrt–Mehrens Margret
Published: May 2018

In this study Si‐alloy/graphite composite electrodes are manufactured using water‐soluble poly‐acrylic acid (PAA) binder of different molecular weights (250, 450 and 1250 kg mol−1). The study aims to assess the behavior of the different binders across all the steps needed for electrodes preparation and on their influence on the electrodes electrochemical behavior. At first, rheological properties of the water‐based slurries containing Si‐alloy, graphite, conductive carbon and PAA are studied. After coating, the adhesion strength and electronic conductivity of the manufactured electrodes are evaluated and compared. Finally, the electrochemical behavior of the composite anodes is evaluated. The electrodes show high gravimetric as well as high areal capacity (∼750 mAh/g; ∼3 mAh/cm2). The influence of the binder on the first cycle irreversible loss is considered as well as its effectiveness in minimizing the electrode volume variation upon lithiation/de‐lithiation. It is finally demonstrated that the use of 8 wt.% of PAA‐250k in the electrode formulation leads to the best performance in terms of high rate performance and long term stability.
Accurate nonlinear mapping between MNI volumetric and FreeSurfer surface coordinate systems
Authors: Wu Jianxiao , Ngo Gia H. , Greve Douglas , Li Jingwei , He Tong , Fischl Bruce , Eickhoff Simon B. , Yeo B.T. Thomas
Published: May 2018

The results of most neuroimaging studies are reported in volumetric (e.g., MNI152) or surface (e.g., fsaverage) coordinate systems. Accurate mappings between volumetric and surface coordinate systems can facilitate many applications, such as projecting fMRI group analyses from MNI152/Colin27 to fsaverage for visualization or projecting resting‐state fMRI parcellations from fsaverage to MNI152/Colin27 for volumetric analysis of new data. However, there has been surprisingly little research on this topic. Here, we evaluated three approaches for mapping data between MNI152/Colin27 and fsaverage coordinate systems by simulating the above applications: projection of group‐average data from MNI152/Colin27 to fsaverage and projection of fsaverage parcellations to MNI152/Colin27. Two of the approaches are currently widely used. A third approach (registration fusion) was previously proposed, but not widely adopted. Two implementations of the registration fusion (RF) approach were considered, with one implementation utilizing the Advanced Normalization Tools (ANTs). We found that RF‐ANTs performed the best for mapping between fsaverage and MNI152/Colin27, even for new subjects registered to MNI152/Colin27 using a different software tool (FSL FNIRT). This suggests that RF‐ANTs would be useful even for researchers not using ANTs. Finally, it is worth emphasizing that the most optimal approach for mapping data to a coordinate system (e.g., fsaverage) is to register individual subjects directly to the coordinate system, rather than via another coordinate system. Only in scenarios where the optimal approach is not possible (e.g., mapping previously published results from MNI152 to fsaverage), should the approaches evaluated in this manuscript be considered. In these scenarios, we recommend RF‐ANTs (https://github.com/ThomasYeoLab/CBIG/tree/master/stable_projects/registration/Wu2017_RegistrationFusion).
TitleIXStory Club: Creating Possibilities for Minoritized Middle School Girls in Physical Activity
Authors: Degener Rebekah May
Published: May 2018

The author draws on the ideas of counter‐storytelling and critical race methodology to examine the ways that urban, racially minoritized middle school girls create hope in sports and physical activity contexts. Although the passage of TitleIXhas brought more equal opportunities for many women and girls in sports, racially minoritized female athletes continue to feel opposition to their participation in sports and physical activity. This article identifies how middle school girls use critical counter‐storytelling to name narratives that others hold about them that impact their ability to participate in sports. The author highlights how, when given the opportunity, middle school girls can encourage one another to name and speak back to negative narratives. The author also offers suggestions for how educators might create space to hear the voices of racially minoritized girls in the curriculum.
An evaluation of group activity schedules to promote social play in children with autism
Authors: Akers Jessica S. , Higbee Thomas S. , Gerencser Kristina R. , Pellegrino Azure J.
Published: May 2018

Children with autism spectrum disorder (ASD) often have deficits in social skills and may avoid engaging in play activities with typically developing peers. The purpose of this study was to identify the utility of activity schedules, with embedded scripts, to teach three children with ASD to play a complex social game. Specifically, children with ASD were taught to play hide‐and‐seek with typically developing peers. Once the activity schedules were introduced, participants began engaging in independent hide‐and‐seek behaviors. A secondary purpose of this study was to systematically fade the activity schedules to the least intrusive version. We faded all of the scripts and the majority of activity schedule components for the three participants. Participants continued to play hide‐and‐seek with the faded versions of the schedules in a novel environment and 2 weeks after treatment concluded.
Self‐referenced axial chromatic dispersion measurement in multiphoton microscopy through 2‐color third‐harmonic generation imaging
Authors: Du Yu , Zhuang Ziwei , He Jiexing , Liu Hongji , Qiu Ping , Wang Ke
Published: May 2018

With tunable excitation light, multiphoton microscopy is widely used for imaging biological structures at subcellular resolution. Axial chromatic dispersion, present in virtually every transmissive optical system including the multiphoton microscope, leads to focal (and the resultant image) plane separation. Here, we experimentally demonstrate a technique to measure the axial chromatic dispersion in a multiphoton microscope, using simultaneous 2‐color third‐harmonic generation imaging excited by a 2‐color soliton source with tunable wavelength separation. Our technique is self‐referenced, eliminating potential measurement error when 1‐color tunable excitation light is used which necessitates reciprocating motion of the mechanical translation stage. Using this technique, we demonstrate measured axial chromatic dispersion with 2 different objective lenses in a multiphoton microscope. Further measurement in a biological sample also indicates that this axial chromatic dispersion, in combination with 2‐color imaging, may open up opportunity for simultaneous imaging of 2 different axial planes.
Functional optical coherence tomography of neurovascular coupling interactions in the retina
Authors: Son Taeyoon , Alam Minhaj , Toslak Devrim , Wang Benquan , Lu Yiming , Yao Xincheng
Published: May 2018

Quantitative evaluation of retinal neurovascular coupling is essential for a better understanding of visual function and early detection of eye diseases. However, there is no established method to monitor coherent interactions between stimulus‐evoked neural activity and hemodynamic responses at high resolution. Here, we report a multimodal functional optical coherence tomography (OCT) imaging methodology to enable concurrent intrinsic optical signal (IOS) imaging of stimulus‐evoked neural activity and hemodynamic responses at capillary resolution. OCT angiography guided IOS analysis was used to separate neural‐IOS and hemodynamic‐IOS changes in the same retinal image sequence. Frequency flicker stimuli evoked neural‐IOS changes in the outer retina; that is, photoreceptor layer, first and then in the inner retina, including outer plexus layer (OPL), inner plexiform layer (IPL), and ganglion cell layer (GCL), which were followed by hemodynamic‐IOS changes primarily in the inner retina; that is, OPL, IPL, and GCL. Different time courses and signal magnitudes of hemodynamic‐IOS responses were observed in blood vessels with various diameters.
Exploring the effect of vitamin E in cancer chemotherapy—A biochemical and biophysical insight
Authors: Bhori Mustansir , Singh Kanchanlata , Marar Thankamani , Chilakapati Murali Krishna
Published: May 2018

Many oncologists contend that patient undergoing chemotherapy must avoid antioxidant supplementation as it may interfere with the activity of the drug. In the present investigation, we have explored the influence of vitamin E, a well‐known antioxidant on Camptothecin (CPT), a potent anti‐cancer drug induced cell apoptosis and death of cervical cancer cells. HeLa cells were treated with different concentrations of CPT in presence and absence of 100 μm vitamin E. Treated cells were subjected to cytotoxicity studies, catalase assay, DNA fragmentation assay, clonogenic assay and flow cytometry based apoptosis detection. Also, Raman spectroscopy a label free technique which provides global information, in conjunction with multivariate tools like PCA, PCLDA and FDA, was investigated to explore vitamin E supplementation induced alterations. Our data based on biochemical and biophysical experimental analysis reveals that CPT causes DNA damage along with protein and lipid alteration culminating in cell death. Importantly, Raman spectroscopic analysis could uniquely differentiate the cluster of control and vitamin E control from CPT and CPT + Vit E treated cells. We conclusively prove that presence of vitamin E at 100 μM concentration shows promising antioxidant activity and displays no modulatory role on CPT induced effect, thereby causing no possible hindrance with the efficacy of the drug. Vitamin E may prove beneficial to alleviate chemotherapy associated side effects in patients during clinical settings which may open the doors further for subsequent exploration in in vivo preclinical studies.
Hybrid fed‐batch bioreactor operation design: control of substrate uptake enhances recombinant protein production in high‐cell‐density fermentations
Authors: Çalık Pınar , Hoxha Bebeta , Çalık Güzide , Özdamar Tunçer H
Published: May 2018

BACKGROUND

The hybrid fed‐batch bioreactor (HFBB) operation is a novel design method for high‐cell‐density fermentations. It employs fed‐batch and batch operations, starting with fed‐batch that in turn shifts to the next, and proceeds in successive cycles to enhance production and productivity by controlling the substrate uptake rate.

RESULTS

The method was tested for the production of recombinant human growth hormone (rhGH) in Pichia pastoris under GAP promoter with carbon sources of (i) glucose and (ii) pre‐treated hydrolyzed sugar‐beet molasses containing equimolar glucose and fructose. The superior strategies were: (i) GH2, a HFBB with glucose feeding composed of ΔtFB = 1.5 h fed‐batch periods with continuous‐feed stream designed with the pre‐determined growth rate µ = 0.10 h−1, which shift in turn to ΔtB = 0.5 h batch periods; and (ii) MH2, a HFBB with molasses feeding designed in a similar way to GH2. The highest rhGH production attained in GH2 was 611 mg dm−3 at 8 h, whereas it was 625 mg dm−3 at 13.5 h in MH2. In GH2, rhGH production increased 1.37‐fold in half the cultivation time of GH2. However, in MH2 with dual carbon sources enriched with other substrates, higher rhGH production was obtained at the cost of lower productivity.

CONCLUSION

The HFBB is a powerful design method with a single carbon source which improves the productivity of high‐cell‐density fermentations. However, with molasses upon shifting to batch operations, the uptake of accumulated fructose is continued. Thus, the glamour of the HFBB is hindered for complex media fermentations to an extent, because multi‐carbon sources contribute to the growth during the batch periods by lengthening the cultivation time. © 2018 Society of Chemical Industry