bluuebunny/crossref_metadata_2025 huggingface dataset:
Space Weather Influence on Electromagnetic Geosynchronous Debris Perturbations Using Statistical Fluxes
Authors: Hughes Joseph , Schaub Hanspeter
Published: February 2018

Due to the space plasma and the Sun, spacecraft at geosynchronous Earth orbit can charge naturally negative tens of kV. This charging can cause arcing which can damage spacecraft electronics and solar panels. A charged spacecraft will also experience a perturbative force and torque due to Earth's electric and magnetic fields. These electromagnetic perturbations have recently been postulated to cause significant orbital changes for lightweight debris objects. This paper investigates the effects of electromagnetic perturbations by using a charging model that uses measured flux distributions to better simulate natural charging and includes the convection electric field. This is done for a calm space weather case of KP = 2−, a stormy case where KP = 8, and a worst possible case where the voltage is held at −30 kV the entire time. It is found that neglecting electromagnetic effects on lightweight Mylar debris can lead to 100 km displacements after only a one orbit, and the covariance associated with such objects must be increased during periods of high charging.
Update on the Worsening Particle Radiation Environment Observed by CRaTER and Implications for Future Human Deep‐Space Exploration
Authors: Schwadron N. A. , Rahmanifard F. , Wilson J. , Jordan A. P. , Spence H. E. , Joyce C. J. , Blake J. B. , Case A. W. , de Wet W. , Farrell W. M. , Kasper J. C. , Looper M. D. , Lugaz N. , Mays L. , Mazur J. E. , Niehof J. , Petro N. , Smith C. W. , Townsend L. W. , Winslow R. , Zeitlin C.
Published: February 2018

Over the last decade, the solar wind has exhibited low densities and magnetic field strengths, representing anomalous states that have never been observed during the space age. As discussed by Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084), the cycle 23–24 solar activity led to the longest solar minimum in more than 80 years and continued into the “mini” solar maximum of cycle 24. During this weak activity, we observed galactic cosmic ray fluxes that exceeded theERobserved small solar energetic particle events. Here we provide an update to the Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084) observations from the Cosmic Ray Telescope for the Effects of Radiation (CRaTER) on the Lunar Reconnaissance Orbiter. The Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084) study examined the evolution of the interplanetary magnetic field and utilized a previously published study by Goelzer et al. (2013, https://doi.org/10.1002/2013JA019404) projecting out the interplanetary magnetic field strength based on the evolution of sunspots as a proxy for the rate that the Sun releases coronal mass ejections. This led to a projection of dose rates from galactic cosmic rays on the lunar surface, which suggested a ∼20% increase of dose rates from one solar minimum to the next and indicated that the radiation environment in space may be a worsening factor important for consideration in future planning of human space exploration. We compare the predictions of Schwadron, Blake, et al. (2014, https://doi.org/10.1002/2014SW001084) with the actual dose rates observed by CRaTER in the last 4 years. The observed dose rates exceed the predictions by ∼10%, showing that the radiation environment is worsening more rapidly than previously estimated. Much of this increase is attributable to relatively low‐energy ions, which can be effectively shielded. Despite the continued paucity of solar activity, one of the hardest solar events in almost a decade occurred in September 2017 after more than a year of all‐clear periods. These particle radiation conditions present important issues that must be carefully studied and accounted for in the planning and design of future missions (to the Moon, Mars, asteroids, and beyond).
Seasonal Sensitivity of the Hadley Cell and Cross‐Hemispheric Responses to Diabatic Heating in an Idealized GCM
Authors: Baker Hugh S. , Mbengue Cheikh , Woollings Tim
Published: February 2018

The seasonal sensitivity of the Hadley cell to localized diabatic forcing is studied using a dry idealized atmospheric general circulation model. Sensitivities are broadly consistent with Hadley cell responses in observations and climate models to El Niño–Southern Oscillation and global warming‐like forcings. However, the exact seasonal sensitivity patterns highlight the importance of reducing the uncertainty in the size and position of expected anthropogenic forcings to understand how the atmospheric circulation will respond. The sensitivities reveal cross‐hemispheric Hadley cell responses that project onto the eddy‐driven jets and storm tracks. For summer hemisphere heating, the winter Hadley cell extent and jet latitude responses are highly correlated. For winter hemisphere heating, the summer Hadley cell extent and jet speed responses are highly correlated. These seasonal differences arise due to the contrast between the dominant winter Hadley cell and weaker summer Hadley cell.
Irradiation Enhances Strength and Deformability of Nano‐Architected Metallic Glass
Authors: Thompson Rachel L. , Wang Yongqiang , Greer Julia R.
Published: February 2018

The quest for radiation‐damage tolerant materials has found good candidates in nanoporous metals, whose abundance of free surfaces provides ample sinks for radiation‐induced defects, as well as in metallic glasses, whose characteristic failure via shear banding can be alleviated by irradiation. This type of catastrophic failure in metallic glass can also be suppressed by reducing their dimensions to the nanoscale. To combine the beneficial effects of resilience against irradiation in materials containing many free surfaces and nano‐sized metallic glasses, the authors fabricate Zr–Ni–Al metallic glass nano‐architecture and irradiate them with 12 MeV Ni4+ ions. These 3D nanolattices are composed of hollow beams of sputtered metallic glass with beam wall thicknesses ≈10–100 nm, with a relative density of ≈5%, which renders them to be 20 times lighter than their bulk‐level counterparts. The authors find that the thickest‐walled nanolattices, those with a median wall thickness of ≈88 nm, are able to withstand irradiation without significant contraction; all other substantially shrunk; and collapsed upon irradiation. In situ nanomechanical experiments on the irradiated samples compressed inside a scanning electron microscope (SEM) reveal substantial improvement in mechanical response upon irradiation, with an average increase in yield strength of 35.7% and a significant enhancement in deformability. Enhanced deformability upon irradiation is apparent from the nanolattices' accommodation of larger strains before any kind of failure, as well as the presence of smaller strain bursts and stress drops throughout the stress–strain response. The irradiated nanolattices are largely intact after compression, with in situ SEM videos demonstrating a layer‐by‐layer like collapse in the irradiated nanolattices in contrast to the catastrophic failure with complete destruction of the failed layers observed in equivalent as‐fabricated samples. This work points to nano‐architected metallic glasses being a promising candidate for creating ultra‐lightweight, radiation tolerant materials, and irradiation as a promising technique for improving the mechanical response of metallic glass nanolattices with stiffness on the order of 250 MPa.
Nonhalogen Solvent‐Processed Asymmetric Wide‐Bandgap Polymers for Nonfullerene Organic Solar Cells with Over 10% Efficiency
Authors: An Yongkang , Liao Xunfan , Chen Lie , Yin Jingping , Ai Qingyun , Xie Qian , Huang Bin , Liu Feng , Jen Alex K.‐Y. , Chen Yiwang
Published: February 2018

Two new wide‐bandgap D–A–π copolymer donor materials, PBDT‐2TC and PBDT‐S‐2TC, based on benzodithiophene and asymmetric bithiophene with one carboxylate (2TC) substituent are synthesized by a facile approach for fullerene‐free organic solar cells (OSCs). The combination of one carboxylate‐substituted thiophene with one thiophene bridge in the backbone substantially reduces the steric hindrance, thereby favoring a planar geometry for efficient charge transport and molecular packing. A reasonable highest‐occupied‐molecular‐orbital energy level in relation to that of the acceptor and balanced hole and electron transport are observed for both polymers. This asymmetric structure unit is flexible and versatile, allowing the absorption, energy levels, and morphology of the blend films to be tailored. Fullerene‐free OSCs based on PBDT‐S‐2TC:ITIC achieve a high power conversion efficiency of 10.12%. More impressively, a successful nonhalogen solvent‐processed solar cell with 9.55% efficiency is also achieved, which is one of the highest values for a fullerene‐free OSC processed using an ecofriendly solvent.
Amorphizing of Cu Nanoparticles toward Highly Efficient and Robust Electrocatalyst for CO2 Reduction to Liquid Fuels with High Faradaic Efficiencies
Authors: Duan Yan‐Xin , Meng Fan‐Lu , Liu Kai‐Hua , Yi Sha‐Sha , Li Si‐Jia , Yan Jun‐Min , Jiang Qing
Published: February 2018

Conversion of carbon dioxide (CO2) into valuable chemicals, especially liquid fuels, through electrochemical reduction driven by sustainable energy sources, is a promising way to get rid of dependence on fossil fuels, wherein developing of highly efficient catalyst is still of paramount importance. In this study, as a proof‐of‐concept experiment, first a facile while very effective protocol is proposed to synthesize amorphous Cu NPs. Unexpectedly, superior electrochemical performances, including high catalytic activity and selectivity of CO2 reduction to liquid fuels are achieved, that is, a total Faradaic efficiency of liquid fuels can sum up to the maximum value of 59% at −1.4 V, with formic acid (HCOOH) and ethanol (C2H6O) account for 37% and 22%, respectively, as well as a desirable long‐term stability even up to 12 h. More importantly, this work opens a new avenue for improved electroreduction of CO2 based on amorphous metal catalysts.
Facile Nanopatterning of PEDOT:PSS Thin Films
Authors: ElMahmoudy Mohammed , Charrier Anne M. , Malliaras George G. , Sanaur Sébastien
Published: February 2018

Nanopatterned conducting polymer poly(3,4‐ethylenedioxythiophene) poly(styrene sulfonate) (PEDOT:PSS) films are obtained using a new, facile fabrication method. In this method, an epoxy supporting layer is used to facilitate the transfer of nanopatterns from a polydimethylsiloxane mold to rigid or flexible substrates. This process overcomes several limitations that are previously introduced when using other nanopatterning techniques such as nanoimprint lithography and capillary force lithography. Two sets of nanopatterned PEDOT:PSS/Gold (Au) electrodes are fabricated with different dimensions: set 1 with 87 nm linewidth, 140 nm pitch, 30 nm depth; and set 2 with 157 nm linewidth, 280 nm pitch, 26 nm depth, respectively. The electrochemical impedance of these electrodes is measured to be lower than that of flat electrodes fabricated following the same process. These findings open the way for fabricating smaller electrodes with reduced impedance. Possible applications can be in the field of biosensing, neural recordings, and interfaces, where decreasing the contact impedance plays a key role.
Molecular Engineering Using an Anthanthrone Dye for Low‐Cost Hole Transport Materials: A Strategy for Dopant‐Free, High‐Efficiency, and Stable Perovskite Solar Cells
Authors: Pham Hong Duc , Do Thu Trang , Kim Jinhyun , Charbonneau Cecile , Manzhos Sergei , Feron Krishna , Tsoi Wing Chung , Durrant James R. , Jain Sagar M. , Sonar Prashant
Published: February 2018

In this report, highly efficient and humidity‐resistant perovskite solar cells (PSCs) using two new small molecule hole transporting materials (HTM) made from a cost‐effective precursor anthanthrone (ANT) dye, namely, 4,10‐bis(1,2‐dihydroacenaphthylen‐5‐yl)‐6,12‐bis(octyloxy)‐6,12‐dihydronaphtho[7,8,1,2,3‐nopqr]tetraphene (ACE‐ANT‐ACE) and 4,4′‐(6,12‐bis(octyloxy)‐6,12‐dihydronaphtho[7,8,1,2,3‐nopqr]tetraphene‐4,10‐diyl)bis(N,N‐bis(4‐methoxyphenyl)aniline) (TPA‐ANT‐TPA) are presented. The newly developed HTMs are systematically compared with the conventional 2,2′,7,7′‐tetrakis(N,N′‐di‐p‐methoxyphenylamino)‐9,9′‐spirbiuorene (Spiro‐OMeTAD). ACE‐ANT‐ACE and TPA‐ANT‐TPA are used as a dopant‐free HTM in mesoscopic TiO2/CH3NH3PbI3/HTM solid‐state PSCs, and the performance as well as stability are compared with Spiro‐OMeTAD‐based PSCs. After extensive optimization of the metal oxide scaffold and device processing conditions, dopant‐free novel TPA‐ANT‐TPA HTM‐based PSC devices achieve a maximum power conversion efficiency (PCE) of 17.5% with negligible hysteresis. An impressive current of 21 mA cm−2 is also confirmed from photocurrent density with a higher fill factor of 0.79. The obtained PCE of 17.5% utilizing TPA‐ANT‐TPA is higher performance than the devices prepared using doped Spiro‐OMeTAD (16.8%) as hole transport layer at 1 sun condition. It is found that doping of LiTFSI salt increases hygroscopic characteristics in Spiro‐OMeTAD; this leads to the fast degradation of solar cells. While, solar cells prepared using undoped TPA‐ANT‐TPA show dewetting and improved stability. Additionally, the new HTMs form a fully homogeneous and completely covering thin film on the surface of the active light absorbing perovskite layers that acts as a protective coating for underlying perovskite films. This breakthrough paves the way for development of new inexpensive, more stable, and highly efficient ANT core based lower cost HTMs for cost‐effective, conventional, and printable PSCs.
Defective Carbon–CoP Nanoparticles Hybrids with Interfacial Charges Polarization for Efficient Bifunctional Oxygen Electrocatalysis
Authors: Lin Yunxiang , Yang Li , Zhang Youkui , Jiang Hongliang , Xiao Zijian , Wu Chuanqiang , Zhang Guobin , Jiang Jun , Song Li
Published: February 2018

The development of efficient catalysts for both oxygen reduction and evolution reactions (oxygen reduction reaction (ORR) and oxygen evolution reaction (OER)) is central to regenerative fuel cells and rechargeable metal–air batteries. It is highly desirable to achieve the efficient integration of dual active components into the catalysts and to understand the interaction between the dual components. Here, a facile approach is demonstrated to construct defective carbon–CoP nanoparticle hybrids as bifunctional oxygen electrocatalysts, and further probe the interfacial charge distribution behavior. By combining multiple synchrotron‐based X‐ray spectroscopic characterizations with density functional theory calculations, the interfacial charge polarization with the electrons gathering at the defective carbon surface and the holes gathering at the CoP surface due to strong interfacial coupling is revealed, which simultaneously facilitates the ORR and OER with remarkable bifunctional oxygen electrode activities. This work not only offers a bifunctional oxygen catalyst with outstanding performance, but also unravels the promoting factor of the hybrids from the view of interfacial charge distribution.
Fully resolved simulations of single char particle combustion using a ghost‐cell immersed boundary method
Authors: Luo Kun , Mao Chaoli , Fan Jianren , Zhuang Zhenya , Haugen Nils Erland L.
Published: February 2018

A novel ghost‐cell immersed boundary method for fully resolved simulation of char particle combustion has been developed. The boundary conditions at the solid particle surface, such as velocity, temperature, density, and chemical species concentration, are well enforced through the present method. Two semiglobal heterogeneous reactions and one homogeneous reaction are used to describe the chemical reactions in the domain, and the Stefan flow caused by the heterogeneous reactions is considered. A satisfactory agreement can be found between the present simulation results and experimental data in the literature. The method is then used to investigate the combustion property of a char particle and the interaction between CO2 gasification and O2 oxidation. Furthermore, combustion effect on the exchange of mass, momentum and energy between gas‐ and solid‐ phase is explored. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2851–2863, 2018
Recombinantly expressed gas vesicles as nanoscale contrast agents for ultrasound and hyperpolarized MRI
Authors: Farhadi Arash , Ho Gabrielle , Kunth Martin , Ling Bill , Lakshmanan Anupama , Lu George J , Bourdeau Raymond W. , Schröder Leif , Shapiro Mikhail G.
Published: February 2018

Ultrasound and hyperpolarized magnetic resonance imaging enable the visualization of biological processes in deep tissues. However, few molecular contrast agents are available to connect these modalities to specific aspects of biological function. We recently discovered that a unique class of gas‐filled protein nanostructures known as gas vesicles could serve as nanoscale molecular reporters for these modalities. However, the need to produce these nanostructures via expression in specialized cultures of cyanobacteria or haloarchaea limits their broader adoption by other laboratories and hinders genetic engineering of their properties. Here, we describe recombinant expression and purification of Bacillus megaterium gas vesicles using a common laboratory strain of Escherichia coli, and characterize the physical, acoustic, and magnetic resonance properties of these nanostructures. Recombinantly expressed gas vesicles produce ultrasound and hyperpolarized 129Xe MRI contrast at subnanomolar concentrations, thus validating a simple platform for their production and engineering. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2927–2933, 2018
Chemical composition of glandular secretions from a pair‐living monogamous primate: Sex, age, and gland differences in captive and wild owl monkeys (Aotus spp.)
Authors: Spence‐Aizenberg Andrea , Kimball Bruce A. , Williams Lawrence E. , Fernandez‐Duque Eduardo
Published: February 2018

Broadening our knowledge of olfactory communication in strictly monogamous systems can inform our understanding of how chemosignals may facilitate social and reproductive behavior between the sexes. Compared to other social and mating systems, relatively little is known about olfactory communication in strictly monogamous non‐human primates. Furthermore, platyrrhines are not well represented in chemical analyses of glandular secretions. We conducted semi‐quantitative headspace gas chromatography with mass spectrometry to investigate the chemical components of glandular secretions from the subcaudal and pectoral glands of a strictly pair‐living platyrrhine, the owl monkey (Aotus spp.). In this study, the first chemical analysis of a wild platyrrhine population, our goals were to (1) conduct a robust analysis of glandular secretions from both captive and wild owl monkey populations and (2) identify whether biologically relevant traits are present in glandular secretions. We also compared and contrasted the results between two Aotus species in different environmental contexts: wild Aotus azarae (N = 33) and captive A. nancymaae (N = 104). Our findings indicate that secretions from both populations encode sex, gland of origin, and possibly individual identity. These consistent patterns across species and contexts suggest that secretions may function as chemosignals. Our data also show that wild A. azarae individuals are chemically discriminated by age (adult or subadult). Among the captive A. nanycmaae, we found chemical differences associated with location, possibly caused by dietary differences. However, there was no noticeable effect of contraception on the chemical profiles of females, nor evidence that closely related individuals exhibit more similar chemical profiles in A. nancymaae. Overall, our data suggest that glandular secretions of both wild and captive Aotus convey specific information. Future studies should use behavioral bioassays to evaluate the ability of owl monkeys to detect signals, and consider whether odor may ultimately facilitate social and sexual relationships between male and female owl monkeys.
Mississippian subadults from the Middle Cumberland and Eastern regions of Tennessee: Biological indicators of population interaction
Authors: Scopa Kelso Rebecca
Published: February 2018

Objectives

Human subadult skeletal remains can provide a unique perspective into biosocial aspects of Mississippian period population interactions within and between the Middle Cumberland (MCR) and Eastern Tennessee Regions (ETR). The majority of previous studies have concentrated on adult skeletal remains, leaving out a large and extremely important population segment.

Methods

Skeletal indicators of disease, growth, body proportions, and metabolic stress were collected from subadult remains from five archaeological sites over several temporal periods. Crucial to overcoming limitations associated with the osteological paradox, the biological results were placed into an archaeological context based on prior studies as well as paleoclimatological data.

Results

Results reveal homogeneity both within and between regions for most skeletal indicators. However, MCR individuals exhibit a higher frequency of pathology than those from ETC, while stature is significantly lower in younger subadults from the MCR. Within the ETR, there is no evidence for biological differences between Early Dallas and subsequent Late Dallas and Mouse Creek cultural phases. Despite presumed signs of increased conflict at the Dallas site, frequencies and types of skeletal pathology and growth disruptions are comparable to other regional sites.

Conclusions

These findings suggest that despite cultural differences between the ETR and MCR, there was no large‐scale intrusion from an outside population into the ETR during the Late Mississippian Period, or if one occurred, it is biologically invisible. Combined with climatic and archaeobotanical data, results suggest the MCR subadults were under increased stress in their earlier years. This may have been associated with increased interpersonal violence and dependence on few food sources occurring with greater scarcity.
Locomotor activity, growth hormones, and systemic robusticity: An investigation of cranial vault thickness in mouse lines bred for high endurance running
Authors: Copes L. E. , Schutz H. , Dlugsoz E. M. , Judex S. , Garland T.
Published: February 2018

Objectives

To use a mouse model to investigate the relationships among the components of the systemic robusticity hypothesis (SRH): voluntary exercise on wheels, spontaneous physical activity (SPA) in cages, growth hormones, and skeletal robusticity, especially cranial vault thickness (CVT).

Materials and Methods

Fifty female mice from lines artificially selected for high running (HR) and 50 from nonselected control (C) lines were housed in cages with (Active) or without wheels (Sedentary). Wheel running and SPA were monitored daily. The experiment began at 24–27 days of age and lasted 12 weeks. Food consumption was measured weekly. Mice were skeletonized and their interparietal, parietal, humerus, and femur were µCT scanned. Mean total thickness of the parietal and interparietal bones was determined, along with thickness of the cortical and diploe layers individually. Geometric cross‐sectional indicators of strength were calculated for the long bones. Blood samples were assayed for IGF‐1 and IGFBP‐3.

Results

Physical activity differed significantly among groups, based both on linetype (C vs. HR) and activity (A vs. S). However, contrary to our predictions, the ratio of IGF‐1 to IGFBP‐3 was higher in C mice than in HR mice. Neither CVT nor postcranial robusticity was affected by linetype or activity, nor were most measures of CVT and postcranial robusticity significantly associated with one another.

Discussion

Our results fail to provide support for the systemic robusticity hypothesis, suggesting it is important to rethink the long‐standing theory that increased CVT in Homo erectus reflects increased physical activity compared other hominin species.
ADR Brief
Authors: Lawrence James K.L.
Published: February 2018

Your client (or if you are an in‐house attorney, imagine your chief executive officer) at Bridges Ltd. just called, and in a voice suggesting grave concern informed you that a bridge support failed on Highway 101 over Werth Road. Its collapse crushed a car below killing the driver and injuring a passenger.
Nanobody‐Enabled Reverse Pharmacology on G‐Protein‐Coupled Receptors
Authors: Pardon Els , Betti Cecilia , Laeremans Toon , Chevillard Florent , Guillemyn Karel , Kolb Peter , Ballet Steven , Steyaert Jan
Published: February 2018

The conformational complexity of transmembrane signaling of G‐protein‐coupled receptors (GPCRs) is a central hurdle for the design of screens for receptor agonists. In their basal states, GPCRs have lower affinities for agonists compared to their G‐protein‐bound active state conformations. Moreover, different agonists can stabilize distinct active receptor conformations and do not uniformly activate all cellular signaling pathways linked to a given receptor (agonist bias). Comparative fragment screens were performed on a β2‐adrenoreceptor–nanobody fusion locked in its active‐state conformation by a G‐protein‐mimicking nanobody, and the same receptor in its basal‐state conformation. This simple biophysical assay allowed the identification and ranking of multiple novel agonists and permitted classification of the efficacy of each hit in agonist, antagonist, or inverse agonist categories, thereby opening doors to nanobody‐enabled reverse pharmacology.
Genexpression auf DNA‐Biochips: Strukturierung durch Strangverdrängungs‐Lithographie
Authors: Pardatscher Günther , Schwarz‐Schilling Matthaeus , Daube Shirley S. , Bar‐Ziv Roy H. , Simmel Friedrich C.
Published: February 2018

Die lithographische Strukturierung von DNA‐Molekülen ermöglicht die räumliche Organisation von zellfreien, genetischen Schaltkreisen unter streng kontrollierten Bedingungen. Im Folgenden beschreiben wir einen biokompatiblen, DNA‐basierten Chip‐Photolack namens “Bephore”, der mittels Photo‐ und Elektronenstrahllithographie strukturiert werden kann. Das Verfahren basiert auf der Spaltung eines chemisch modifizierten, haarnadelförmigen DNA‐Moleküls durch ultraviolettes Licht oder Elektronen, und auf einer nachfolgenden DNA‐Strangverdrängungsreaktion. Hierbei werden alle Schritte in wässriger Lösung und ohne eine chemische Entwicklung des Photolacks durchgeführt, wodurch sich der lithographische Prozess als besonders robust und biokompatibel auszeichnet. Bephore eignet sich auch für ein mehrstufiges lithographisches Verfahren und erlaubt dadurch die Immobilisierung verschiedener DNA‐Moleküle mit Mikrometer‐Präzision. Als Anwendung für das Verfahren zeigen wir die Expression dreier Gene, die in Kompartimenten auf einem Chip immobilisiert wurden, und die Entstehung der daraus resultierenden, räumlichen Proteinexpressions‐Gradienten.
Li2B12 and Li3B12: Prediction of the Smallest Tubular and Cage‐like Boron Structures
Authors: Dong Xue , Jalife Said , Vásquez‐Espinal Alejandro , Ravell Estefanía , Pan Sudip , Cabellos José Luis , Liang Wei‐yan , Cui Zhong‐hua , Merino Gabriel
Published: February 2018

An intriguing structural transition from the quasi‐planar form of B12 cluster upon the interaction with lithium atoms is reported. High‐level computations show that the lowest energy structures of LiB12, Li2B12, and Li3B12 have quasi‐planar (Cs), tubular (D6d), and cage‐like (Cs) geometries, respectively. The energetic cost of distorting the B12 quasi‐planar fragment is overcompensated by an enhanced electrostatic interaction between the Li cations and the tubular or cage‐like B12 fragments, which is the main reason of such drastic structural changes, resulting in the smallest tubular (Li2B12) and cage‐like (Li3B12) boron structures reported to date.
Gene Expression on DNA Biochips Patterned with Strand‐Displacement Lithography
Authors: Pardatscher Günther , Schwarz‐Schilling Matthaeus , Daube Shirley S. , Bar‐Ziv Roy H. , Simmel Friedrich C.
Published: February 2018

Lithographic patterning of DNA molecules enables spatial organization of cell‐free genetic circuits under well‐controlled experimental conditions. Here, we present a biocompatible, DNA‐based resist termed “Bephore”, which is based on commercially available components and can be patterned by both photo‐ and electron‐beam lithography. The patterning mechanism is based on cleavage of a chemically modified DNA hairpin by ultraviolet light or electrons, and a subsequent strand‐displacement reaction. All steps are performed in aqueous solution and do not require chemical development of the resist, which makes the lithographic process robust and biocompatible. Bephore is well suited for multistep lithographic processes, enabling the immobilization of different types of DNA molecules with micrometer precision. As an application, we demonstrate compartmentalized, on‐chip gene expression from three sequentially immobilized DNA templates, leading to three spatially resolved protein‐expression gradients.
Electron Transfer around a Molecular Corner
Authors: Schmidt Hauke C. , Larsen Christopher B. , Wenger Oliver S.
Published: February 2018

The distance dependence of electron transfer (ET) is commonly investigated in linear rigid rod‐like compounds, but studies of molecular wires with integrated corners imposing 90° angles are very rare. By using spirobifluorene as a key bridging element and by substituting it at different positions, two isomeric series of donor‐bridge‐acceptor compounds with either nearly linear or angled geometries were obtained. Photoinduced ET in both series is dominated by rapid through‐bond hole hopping across oligofluorene bridges over distances of up to 70 Å. Despite considerable conformational flexibility, direct through‐space and through‐solvent ET is negligible even in the angled series. The independence of the ET rate constant on the total number of fluorene units in the angled series is attributed to a rate‐limiting tunneling step through the spirobifluorene corner. This finding is relevant for multidimensional ET systems and grids in which individual molecular wires are interlinked at 90° angles.
Manganese‐Catalyzed Carbonylative Annulations for Redox‐Neutral Late‐Stage Diversification
Authors: Liang Yu‐Feng , Steinbock Ralf , Münch Annika , Stalke Dietmar , Ackermann Lutz
Published: February 2018

An inexpensive, nontoxic manganese catalyst enabled unprecedented redox‐neutral carbonylative annulations under ambient pressure. The manganese catalyst outperformed all other typically used base and precious‐metal catalysts. The outstanding versatility of the manganese catalysis manifold was reflected by ample substrate scope, setting the stage for effective late‐stage manipulations under racemization‐free conditions of a wealth of marketed drugs and natural products, including alkaloids, amino acids, steroids, and carbohydrates.
A Delamination Strategy for Thinly Layered Defect‐Free High‐Mobility Black Phosphorus Flakes
Authors: Yang Sheng , Zhang Ke , Ricciardulli Antonio Gaetano , Zhang Panpan , Liao Zhongquan , Lohe Martin R. , Zschech Ehrenfried , Blom Paul W. M. , Pisula Wojciech , Müllen Klaus , Feng Xinliang
Published: February 2018

Extraordinary electronic and photonic features render black phosphorus (BP) an important material for the development of novel electronics and optoelectronics. Despite recent progress in the preparation of thinly layered BP flakes, scalable synthesis of large‐size, pristine BP flakes remains a major challenge. An electrochemical delamination strategy is demonstrated that involves intercalation of diverse cations in non‐aqueous electrolytes, thereby peeling off bulk BP crystals into defect‐free flakes comprising only a few layers. The interplay between tetra‐n‐butylammonium cations and bisulfate anions promotes a high exfoliation yield up to 78 % and large BP flakes up to 20.6 μm. Bottom‐gate and bottom‐contact field‐effect transistors, comprising single BP flakes only a few layers thick, exhibit a high hole mobility of 252±18 cm2 V−1 s−1 and a remarkable on/off ratio of (1.2±0.15)×105 at 143 K under vacuum. This efficient and scalable delamination method holds great promise for development of BP‐based composites and optoelectronic devices.
An Amorphous Noble‐Metal‐Free Electrocatalyst that Enables Nitrogen Fixation under Ambient Conditions
Authors: Lv Chade , Yan Chunshuang , Chen Gang , Ding Yu , Sun Jingxue , Zhou Yansong , Yu Guihua
Published: February 2018

N2 fixation by the electrocatalytic nitrogen reduction reaction (NRR) under ambient conditions is regarded as a potential approach to achieve NH3 production, which still heavily relies on the Haber–Bosch process at the cost of huge energy and massive production of CO2. A noble‐metal‐free Bi4V2O11/CeO2 hybrid with an amorphous phase (BVC‐A) is used as the cathode for electrocatalytic NRR. The amorphous Bi4V2O11 contains significant defects, which play a role as active sites. The CeO2 not only serves as a trigger to induce the amorphous structure, but also establishes band alignment with Bi4V2O11 for rapid interfacial charge transfer. Remarkably, BVC‐A shows outstanding electrocatalytic NRR performance with high average yield (NH3: 23.21 μg h−1 mg−1cat., Faradaic efficiency: 10.16 %) under ambient conditions, which is superior to the Bi4V2O11/CeO2 hybrid with crystalline phase (BVC‐C) counterpart.
Synthesis and characterization of lignin–poly(acrylamide)–poly(2‐methacryloyloxyethyl) trimethyl ammonium chloride copolymer
Authors: Hasan Agha , Fatehi Pedram
Published: February 2018

In this work, two monomers, acrylamide (AM) and [2‐(methacryloyloxy)ethyl]trimethylammonium chloride (DMC) were copolymerized from kraft lignin (KL) in an aqueous suspension initiated by free radical copolymerization in the presence of potassium persulfate. The impact of copolymerization conditions on the charge density and molecular weight of the copolymers was investigated. The molecular weight and mass balance analyses confirmed that the homopolymer [polyDMC (PDMC) and polyAM (PAM)] and undesired copolymer (AM–DMC) productions dominated as time, initiator, and DMC dosage increased more than the optimum values. The activation energy of the polymerization of KL and AM (43.02 kJ mol−1), KL and DMC (21.99 kJ mol−1), AM (14.54 kJ mol−1), DMC (10.34 kJ mol−1), and AM and DMC (18.13 kJ mol−1) was determined. Proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, thermogravimetric analysis, and elemental analysis confirmed the production of KL–AM–DMC copolymer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46338.
Simultaneously reinforcing and toughening epoxy network with a novel hyperbranched polysiloxane modifier
Authors: Liu Hanchao , Gao Xiaoxiao , Deng Bo , Huang Guangsu
Published: February 2018

A novel hyperbranched polysiloxane (HBPSi) was prepared and cured into an epoxy–aromatic amine network without phase separation. A moderate content of HBPSi increased the crosslinking density of the crosslinking network because of the active amino groups on the HBPSi. Meanwhile, the secondary amine on the HBPSi molecules improved the homogeneity of the epoxy network. At a 5 wt % HBPSi content, the tensile strength, tensile modulus, and flexural modulus were enhanced by 17.6%, 13.7%, and 17.5%, respectively, compared with those of the neat epoxy resin. Meanwhile, the elongation at break and impact strength were 63.3% and 49.1% higher than those of the neat epoxy resin, respectively. HBPSi also significantly increased the char yield of the material and decreased the thermal weight loss rate; this indicated an improved thermal stability. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46340.
Facile preparation and characterization of soluble aramid
Authors: Zhou Sheng , Wang Xiaolu , Zhang Wei , Zhang Mengyao , Zhang Xiaoli , Zhao Ning , Liu Ruigang , Xu Jian , Shen Zhihao , Fan Xinghe
Published: February 2018

It remains a problem to prepare cost‐effective aramid with good solubility via a simple method since the commercialization of aromatic polyamides such as Kevlar and Nomex by DuPont in 1960s. Herein, we report the facile preparation and properties of an aromatic polyamide copolymerized by 2,6‐naphthalene dichloride (26N‐COCl), 4,4′‐oxydianiline, and m‐phenylenediamine. The synthetic route is very facile and cost‐effective. The modified aramids possess excellent comprehensive properties. The polymers are soluble in some organics. Their thermal stabilities are excellent, with 5% weight loss temperatures (Td,5%'s) in air higher than 460 °C and glass transition temperatures (Tg's) higher than 280 °C. These polymers are easily processed into films, fibers, and tubes. The products exhibit high strength. For example, the films have excellent mechanical strength, with a tensile strength up to 139 MPa, a tensile modulus up to 3.45 GPa, and an elongation of 11%. The films are also transparent and fluorescent. The overall properties are better than those of the commercial Nomex. The facilely prepared aramids with good solubility are very promising for commercial use. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46341.
Preparation, analysis, and isothermal crystallization behavior of poly[1,3‐bis(aminomethyl)cyclohexamethylene oxamide]
Authors: Mutua Fredrick Nzioka , Yang Tingting , Gao Yuanbo , Zhu Bo , He Yong
Published: February 2018

Poly[1,3‐bis(aminomethyl)cyclohexaneoxamide] (PBAC2) was synthesized using 1,3‐bis(aminomethyl)cyclohexane (BAC) and dibutyl oxalate (DO) via spray/solid‐state polycondensation (SSP). The structure of the synthesized polyoxamide was confirmed by 1H‐nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy. The weight average molecular weight (Mw) of the polyoxamides prepared was 1.35 × 105. The polyoxamides showed excellent thermal properties with glass transition temperature (Tg) of 150 °C, melting temperature (Tm) of 318 °C, crystallization temperature(Tc) of 253 °C, and initial degradation temperature (Td) of 417 °C suggesting higher thermal stability than commercial polyamide 6 (Td = 378 °C). Kinetic studies of PBAC2 predicted a two‐dimensional crystal growth. X‐ray diffraction powder diffraction suggested that the polymer has high crystallinity. A saturated water absorption of 2.8 wt % was recorded for the new polyoxamide, giving it a competitive edge for applications in civil aviation, reinforced plastics, and electronics industry where precise dimensional stability and high thermal resistance properties are a priority. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46345.
Preparation of acrylamide‐based poly‐HIPEs with enhanced mechanical strength using PVDBM‐b‐PEG‐emulsified CO2‐in‐water emulsions
Authors: Wang Liwen , Liu Yongjia , Bao Lei , Hu Dongdong , Zong Yuan , Tong Gangsheng , Zhao Ling , Liu Tao
Published: February 2018

Poly(vinyl acetate‐alt‐dibutyl maleate)‐block‐poly(ethylene glycol) (PVDBM‐b‐PEG) copolymers were synthesized via reversible addition–fragmentation chain transfer radical polymerization and used as emulsifiers to form stable CO2‐in‐water high internal phase emulsions (C/W HIPEs). Then, highly interconnected cellular polyacrylamide (PAM) and poly(acrylamide‐co‐N‐hydroxymethyl acrylamide) [P(AM‐co‐HMAM)] poly‐HIPEs with enhanced mechanical strength were prepared based on the stable C/W HIPEs. The porous structures of the PAM poly‐HIPEs, as well as morphology and compressive modulus, could be influenced by the surfactant concentration and the length of the CO2‐philic tails of the surfactants. PAM poly‐HIPEs with the smallest average pore diameter (11.12 ± 0.62 μm) and the highest compressive modulus (22.65 ± 0.10 MPa) could be obtained by using the short CO2‐philic chains of the PVDBM‐b‐PEG surfactant at a high concentration (1.0 wt %). Moreover, with the copolymerization of N‐hydroxymethyl acrylamide (HMAM) comonomers with acrylamide, the compressive modulus of the obtained P(AM‐co‐HMAM) poly‐HIPEs was three times higher than that of PAM poly‐HIPEs. Both PAM and P(AM‐co‐HMAM) poly‐HIPEs were employed as scaffolds to guide H9c2 cardiac muscle cellular growth. Fluorescence images showed that a smaller average pore size and a narrower pore‐size distribution were helpful for cell growth and proliferation on these materials. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46346.
Sodium bicarbonate as novel additive for fabrication of composite nanofiltration membranes with enhanced permeability
Authors: Sun Yongli , Jin Weiguang , Zhang Luhong , Zhang Na , Wang Baoyu , Jiang Bin
Published: February 2018

Thin film composite nanofiltration membranes are frequently used to remove the residual salts from industrial wastewater. However, these nanofiltration membranes often have relatively low fluxes that limit their practical applications. To solve the problem, sodium bicarbonate was introduced into the composite nanofiltration membranes via interfacial polymerization of piperazine (PIP) and 1,3,5‐benzenetricarbonyl trichloride (TMC). The membrane surfaces were characterized by scanning electronic microscopy, attenuated total reflection Fourier transform infrared spectroscopy, electro kinetic analyzer, and contact angle goniometer. The results showed that the addition of sodium bicarbonate generated more tiny cracks on membrane surface and decreased the zeta potential of the membrane, which improved the permeation properties of the membrane without significantly decreasing the rejection against four kinds of salts (Na2SO4, MgSO4, NaCl, MgCl2). The addition of sodium bicarbonate provided a new possibility to improve the permeation properties of thin film composite nanofiltration membranes. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46363.
Multiscale thermal modeling of cured cycloaliphatic epoxy/carbon fiber composites
Authors: Chinkanjanarot Sorayot , Radue Matthew S. , Gowtham S. , Tomasi Julie M. , Klimek‐McDonald Danielle R. , King Julia A. , Odegard Gregory M.
Published: February 2018

Cycloaliphatic epoxies (CEs) are commonly used for structural applications requiring improved resistance to elevated temperatures, UV radiation, and moisture relative to other epoxy materials. Accurate and efficient computational models can greatly facilitate the development of CE‐based composite materials for applications such as Aluminum Conductor Composite Core high‐voltage power lines. In this study, a new multiscale modeling method is developed for CE resins and composite materials to efficiently predict thermal properties (glass‐transition temperature, thermal expansion coefficient, and thermal conductivity). The predictions are compared to experimental data, and the results indicate that the multiscale modeling method can accurately predict thermal properties for CE‐based materials. For 85% crosslink densities, the predicted glass‐transition temperature, thermal expansion coefficient, and thermal conductivity are 279 °C, 109 ppm °C−1, 0.24 W m−1 K−1, respectively. Thus, this multiscale modeling method can be used for the future development of improved CE composite materials for thermal applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46371.
Adaptation, translation, and validation of information literacy assessment instrument
Authors: Hani Syazillah Nordin , Kiran K. , Chowdhury G.
Published: February 2018

The assessment of information literacy (IL) at the school level is mainly dependent on the measurement tools developed by the Western world. These tools need to be efficiently adapted and in most cases translated to allow them to be utilized in other cultures, languages, and countries. To date, there have been no standard guidelines to adapt these tools; hence, the results may be cross‐culturally generalized to a certain extent. Furthermore, most data analyses produce generic outcomes without taking into account the ability of the students, including the difficulty of the test items. The present study proposes a systematic approach for context adaptation and language translation of the preexisting IL assessment tool known as TRAILS‐9 to be used in different languages and context, particularly a Malaysian public secondary school. This study further administers a less common psychometric approach, the Rasch analysis, to validate the adapted instrument. This technique produces a hierarchy of item difficulty within the assessment domain that enables the ability level of the students to be differentiated based on item difficulty. The recommended scale adaptation guidelines are able to reduce the misinterpretation of scores from instruments in multiple languages as well as contribute to parallel development of IL assessment among secondary school students from different populations.
Thermal Transition of Bimetallic Metal–Phenolic Networks to Biomass‐Derived Hierarchically Porous Nanofibers
Authors: Xiao Gao , Chen Wei , Tian Fan , Richardson Joseph J. , Tardy Blaise L. , Liu Minghua , Joshi Neel S. , Guo Junling
Published: February 2018

The development and utilization of biomass resources could contribute to new materials for long‐term sustainable energy storage and environmental applications, reduce environmental impacts, and meet the urgent need for green and sustainable development strategies. Herein, a bimetallic metal–phenolic network (MPN) was applied to incorporate different metallic element species into cattle skin and fabricate collagen‐fiber‐derived complex oxide nanofibers using natural polyphenols (Myrica tannins). Direct thermal transition of these biomass–MPN composites generates hierarchically porous nanofibers possessing micro‐ and mesoporous architectures along with a well‐preserved macroscopic structure. The pore system and complex oxide composition provide excellent photocatalytic performance. This low‐cost, simple, and readily scalable MPN‐based approach provides a straightforward route to synthesize nanostructured materials directly from biomass, which could play important roles in a wide range of potential applications.
Communication of anger versus disappointment in bargaining and the moderating role of power
Authors: van Dijk Eric , van Beest Ilja , van Kleef Gerben A. , Lelieveld Gert‐Jan
Published: February 2018

Emotional expressions can have a pervasive impact on bargaining behavior and outcomes. This widely documented phenomenon implies that in their communications, bargainers may adjust their apparent emotions. In the current paper, we developed a paradigm to study the communication of anger and disappointment, two of the most commonly experienced emotions in bargaining. The results of three experiments show that bargainers often adjust the intensity of their emotions in their communicated emotions. The findings show a differentiated pattern, revealing that bargainers rather exaggerate their disappointment than their anger, especially when the target of their communication is in a high power position. The results are discussed and related to the social functional approach of emotions.