bluuebunny/crossref_metadata_2025 huggingface dataset:
Kallikrein‐related peptidase 4 induces cancer‐associated fibroblast features in prostate‐derived stromal cells
Authors: Kryza Thomas , Silva Lakmali M. , Bock Nathalie , Fuhrman‐Luck Ruth A. , Stephens Carson R. , Gao Jin , Samaratunga Hema ,   Australian Prostate Cancer BioResource, Lawrence Mitchell G. , Hooper John D. , Dong Ying , Risbridger Gail P. , Clements Judith A.
Published: May 2017

The reciprocal communication between cancer cells and their microenvironment is critical in cancer progression. Although involvement of cancer‐associated fibroblasts (CAF) in cancer progression is long established, the molecular mechanisms leading to differentiation of CAFs from normal fibroblasts are poorly understood. Here, we report that kallikrein‐related peptidase‐4 (KLK4) promotes CAF differentiation. KLK4 is highly expressed in prostate epithelial cells of premalignant (prostatic intraepithelial neoplasia) and malignant lesions compared to normal prostate epithelia, especially at the peristromal interface. KLK4 induced CAF‐like features in the prostate‐derived WPMY1 normal stromal cell line, including increased expression of alpha‐smooth muscle actin, ESR1 and SFRP1. KLK4 activated protease‐activated receptor‐1 in WPMY1 cells increasing expression of several factors (FGF1, TAGLN, LOX, IL8, VEGFA) involved in prostate cancer progression. In addition, KLK4 induced WPMY1 cell proliferation and secretome changes, which in turn stimulated HUVEC cell proliferation that could be blocked by a VEGFA antibody. Importantly, the genes dysregulated by KLK4 treatment of WPMY1 cells were also differentially expressed between patient‐derived CAFs compared to matched nonmalignant fibroblasts and were further increased by KLK4 treatment. Taken together, we propose that epithelial‐derived KLK4 promotes tumour progression by actively promoting CAF differentiation in the prostate stromal microenvironment.
Near‐continuous tremor and low‐frequency earthquake activities in the Alaska‐Aleutian subduction zone revealed by a mini seismic array
Authors: Li Bo , Ghosh Abhijit
Published: May 2017

Tectonic tremor and low‐frequency earthquakes (LFEs) are relatively poorly studied in the Alaska‐Aleutian subduction zone due to the limited data availability, difficult logistics, and rugged terrain. Using 2 months of continuous data recorded by a mini seismic array in the Akutan Island, we detect near‐continuous tremor activity with an average of 1.3 h of tectonic tremor per day using a beam backprojection method. Tremor sources are clustered in two patches with an ~25 km gap in between them. In addition, we visually identify three low‐frequency earthquakes, and using them as templates, we detect ~1300 additional LFEs applying a matched‐filter method. Tremor and LFE activities agree well in space and time, and LFEs show a much smaller recurrence interval during tremor than during non‐tremor time periods. Tremor sources propagate both along the strike and dip directions of the subduction fault with velocities ranging between 13 and 110 km/h. Prolific patchy tremor and LFE activities suggest lateral heterogeneity in the locked to freely slipping transition zone, indicating that slow earthquakes may play an important role in the earthquake cycles in this subduction zone.
Field‐aligned current response to solar indices
Authors: Edwards Thom R. , Weimer D. R. , Tobiska W. K. , Olsen Nils
Published: May 2017

Magnetometer data from three satellite missions have been used to analyze and identify the effects of varying solar radiation on the magnitudes and locations of field‐aligned currents in the Earth's upper atmosphere. Data from the CHAMP, Ørsted, and Swarm satellite missions have been brought together to provide a database spanning a 15 year period. The extensive time frame has been augmented by data from the ACE satellite, as well as a number of indices of solar radiation. This data set has been sorted by a number of solar wind, interplanetary magnetic field, and solar radiation indices to provide measurements for the field‐aligned current structures in both hemispheres for arbitrary seasonal tilts. In addition, routines have been developed to extract the total current for different regions of the current structures, including regions 0, 1, and 2. Results from this study have been used to evaluate the effects of variations in four different solar indices on the total current in different regions of the polar cap. While the solar indices do not have major influence on the total current of the polar cap when compared to solar wind and interplanetary magnetic field parameters, it does appear that there is a nonlinear response to increasing F10.7, M10.7, and S10.7 solar indices. Surprisingly, there appears to be a very linear response as Y10.7 solar index increases.
Beaver‐mediated lateral hydrologic connectivity, fluvial carbon and nutrient flux, and aquatic ecosystem metabolism
Authors: Wegener Pam , Covino Tim , Wohl Ellen
Published: May 2017

River networks that drain mountain landscapes alternate between narrow and wide valley segments. Within the wide segments, beaver activity can facilitate the development and maintenance of complex, multithread planform. Because the narrow segments have limited ability to retain water, carbon, and nutrients, the wide, multithread segments are likely important locations of retention. We evaluated hydrologic dynamics, nutrient flux, and aquatic ecosystem metabolism along two adjacent segments of a river network in the Rocky Mountains, Colorado: (1) a wide, multithread segment with beaver activity; and, (2) an adjacent (directly upstream) narrow, single‐thread segment without beaver activity. We used a mass balance approach to determine the water, carbon, and nutrient source‐sink behavior of each river segment across a range of flows. While the single‐thread segment was consistently a source of water, carbon, and nitrogen, the beaver impacted multithread segment exhibited variable source‐sink dynamics as a function of flow. Specifically, the multithread segment was a sink for water, carbon, and nutrients during high flows, and subsequently became a source as flows decreased. Shifts in river‐floodplain hydrologic connectivity across flows related to higher and more variable aquatic ecosystem metabolism rates along the multithread relative to the single‐thread segment. Our data suggest that beaver activity in wide valleys can create a physically complex hydrologic environment that can enhance hydrologic and biogeochemical buffering, and promote high rates of aquatic ecosystem metabolism. Given the widespread removal of beaver, determining the cumulative effects of these changes is a critical next step in restoring function in altered river networks.
Mass transport waves amplified by intense Greenland melt and detected in solid Earth deformation
Authors: Adhikari S. , Ivins E. R. , Larour E.
Published: May 2017

The annual cycle and secular trend of Greenland mass loading are well recorded in measurements of solid Earth deformation. Horizontal crustal displacements can potentially track the spatiotemporal detail of mass changes with great fidelity. Our analysis of Greenland crustal motion data reveals that a significant excitation of horizontal amplitudes occurs during the intense melt years. We discover that solitary seasonal waves of substantial mass transport (1.67 ± 0.54 Gt/month) traveled at an average speed of 7.1 km/month through Rink Glacier in 2012. We deduce that intense surface melting enhanced either basal lubrication or softening of shear margins, or both, causing the glacier to thin dynamically in summer. The newly routed upstream subglacial water was likely to be both retarded and inefficient, thus providing a causal mechanism for the prolonged ice transport to continue well into the winter months. As the climate continues to produce increasingly warmer spring and summer, amplified seasonal waves of mass transport may become ever more present with important ramifications for the future sea level rise.
Hydroacoustic ray theory‐based modeling of T wave propagation in the deep ocean basin offshore eastern Taiwan
Authors: Chen Chin‐Wu , Huang Chen‐Fen , Lin Chien‐Wen , Kuo Ban‐Yuan
Published: May 2017

T waves are conventionally defined as seismically generated acoustic energy propagating horizontally over long distances within the minimum sound speed layer in the ocean (SOFAR axis minimum). However, T waves have also been observed by ocean‐bottom seismometers in ocean basins at depths greater than the SOFAR axis minimum. Previously, nongeometrical processes, such as local scattering at rough seafloor and water‐sediment interface coupling, have been proposed as possible mechanisms for deep seafloor detection of T waves. Here we employ a new T wave modeling approach based on hydroacoustic ray theory to demonstrate that seismoacoustic energy can propagate to reach deep seafloor, previously considered as shadow zone of acoustic propagation. Our new hydroacoustic simulations explain well the observations of T waves on ocean‐bottom seismometers at deep ocean basins east of Taiwan and shed new light on the mechanism for deep ocean T wave propagation.
A new heat flux model for the Antarctic Peninsula incorporating spatially variable upper crustal radiogenic heat production
Authors: Burton‐Johnson A. , Halpin J. A. , Whittaker J. M. , Graham F. S. , Watson S. J.
Published: May 2017

A new method for modeling heat flux shows that the upper crust contributes up to 70% of the Antarctic Peninsula's subglacial heat flux and that heat flux values are more variable at smaller spatial resolutions than geophysical methods can resolve. Results indicate a higher heat flux on the east and south of the Peninsula (mean 81 mW m−2) where silicic rocks predominate, than on the west and north (mean 67 mW m−2) where volcanic arc and quartzose sediments are dominant. While the data supports the contribution of heat‐producing element‐enriched granitic rocks to high heat flux values, sedimentary rocks can be of comparative importance dependent on their provenance and petrography. Models of subglacial heat flux must utilize a heterogeneous upper crust with variable radioactive heat production if they are to accurately predict basal conditions of the ice sheet. Our new methodology and data set facilitate improved numerical model simulations of ice sheet dynamics.
Intercomparison of radar meteor velocity corrections using different ionization coefficients
Authors: Williams E. R. , Wu Y.‐J. , Chau J. , Hsu R.‐R.
Published: May 2017

Sensitive long‐wavelength radar observations of absolute velocity never previously published from Jicamarca are brought to bear on the long‐standing problem of radar detection of slow‐moving meteors. Attention is devoted to evaluating the ionization coefficient β(V) in the critically important velocity range of 11–20 km/s in recent laboratory measurements of Thomas et al. (2016). Theoretical predictions for β(V) based on the laboratory data, on Jones (1997), on Janches et al. (2014), and on Verniani and Hawkins (1964) are used to correct the incoming meteor velocities measured with the sensitive Jicamarca high‐power, large‐aperture radar operating at 6 m wavelength. All corrected distributions are consistent with the predictions of the Nesvorný model in showing pronounced monotonic increases down to the escape velocity (11 km/s). Such distributions may be essential to explaining the pronounced ledge in nighttime electron density and the rapid disappearance of electrons in meteor trails in the altitude range of 80–85 km.
Calculating the inductive electric field in the terrestrial magnetosphere
Authors: Ilie Raluca , Daldorff Lars K. S. , Liemohn Michael W. , Toth Gabor , Chan Anthony A.
Published: May 2017

This study presents a theoretical approach to calculate the inductive electric field, and it is further applied to global MHD simulations of the magnetosphere. The contribution of the inductive component to the total electric field is found by decomposing the motional electric field into a superposition of an irrotational and a solenoidal vector and assuming that the time‐varying magnetic field vanishes on the boundary. We find that a localized change in the magnetic field generates an inductive electric field whose effect extends over all space, meaning that the effect of the inductive electric field is global even if the changes in the magnetic field are localized. Application of this formalism to disturbed times provides strong evidence that during periods of increased activity the electric field induced by the localized change in magnetic field can be comparable to (or larger than) the potential electric fields in certain regions. This induced field exhibits significant spatial and temporal variations, which means that particles that drift into different regions of space are being exposed to different means of acceleration. These results suggest that the inductive electric field could have a substantial contribution to particle energization in the near‐Earth region even though the changes in the magnetic fields occur at distances of several tens of Earth radii. This finding is particularly important for ring current modeling which in many cases excludes inductive contributions to the total particle drift.
Equatorial plasma bubbles: Variations of occurrence and spatial scale in local time, longitude, season, and solar activity
Authors: Smith Jonathon , Heelis Rod A.
Published: May 2017

We examine the location and structure of equatorial topside depletions referred to here as equatorial plasma bubbles (EPBs). The Coupled Ion Neutral Dynamics Investigation Ion Velocity Meter instrument on board the Communication/Navigation Outage Forecasting System is used to measure the ion density from August 2008 to December 2014, a time period in which solar activity transitioned from solar minimum conditions to more moderate solar activity conditions. EPB data are divided into four longitude sectors to determine seasonal and solar cycle variability. In the early phase of the mission, during solar minimum, EPBs occur late in local time, primarily after midnight in all longitude sectors. In the later phase of the mission EPB occurrence after midnight diminishes in all seasons and longitude sectors with the exception of the sector extending from −15° to 60°. An examination of the widths of bubbles indicates that all longitudes show similar distributions between 115 km and 460 km with a prominent peak near 200 km. Among these widths is a distinct width that belongs to discrete individual bubbles with no substructure. We suggest that many bubbles are actually combinations of these individual bubbles; however, in the later phase of the mission there is a population of bubbles that do not conform to this description, perhaps due to the influence of large‐scale plasma motions affecting the background density in which they are embedded.
On the sensitivity of anthropogenic aerosol forcing to model‐internal variability and parameterizing a Twomey effect
Authors: Fiedler S. , Stevens B. , Mauritsen T.
Published: May 2017

Despite efforts to accurately quantify the effective radiative forcing (ERF) of anthropogenic aerosol, the historical evolution of ERF remains uncertain. As a further step toward a better understanding of ERF uncertainty, the present study systematically investigates the sensitivity of the shortwave ERF at the top of the atmosphere to model‐internal variability and spatial distributions of the monthly mean radiative effects of anthropogenic aerosol. For this, ensembles are generated with the atmospheric model ECHAM6.3 that uses monthly prescribed optical properties and changes in cloud‐droplet number concentrations designed to mimic that associated with the anthropogenic aerosol using the new parameterization MACv2‐SP. The results foremost highlight the small change in our best estimate of the global averaged all‐sky ERF associated with a substantially different pattern of anthropogenic aerosol radiative effects from the mid‐1970s (–0.51 Wm–2) and present day (–0.50 Wm–2). Such a small change in ERF is difficult to detect when model‐internal year‐to‐year variability (0.32 Wm–2 standard deviation) is considered. A stable estimate of all‐sky ERF requires ensemble simulations, the size of which depends on the targeted precision, confidence level, and the magnitude of model‐internal variability. A larger effect of the pattern of the anthropogenic aerosol radiative effects on the globally averaged all‐sky ERF (15%) occurs with a strong Twomey effect through lowering the background aerosol optical depth in regions downstream of major pollution sources. It suggests that models with strong aerosol‐cloud interactions could show a moderate difference in the global mean ERF associated with the mid‐1970s to present‐day change in the anthropogenic aerosol pattern.
Photocatalytic Nanofiltration Membranes with Self‐Cleaning Property for Wastewater Treatment
Authors: Lv Yan , Zhang Chao , He Ai , Yang Shang‐Jin , Wu Guang‐Peng , Darling Seth B. , Xu Zhi‐Kang
Published: May 2017

Membrane fouling is one of the most severe problems restricting membrane separation technology for wastewater treatment. This work reports a photocatalytic nanofiltration membrane (NFM) with self‐cleaning property fabricated using a facile biomimetic mineralization process. In this strategy, a polydopamine (PDA)/polyethyleneimine (PEI) intermediate layer is fabricated on an ultrafiltration membrane via a co‐deposition method followed by mineralization of a photocatalytic layer consisting of β‐FeOOH nanorods. The PDA–PEI layer acts both as a nanofiltration selective layer and an intermediate layer for anchoring the β‐FeOOH nanorods via strong coordination complexes between Fe3+ and catechol groups. In visible light, the β‐FeOOH layer exhibits efficient photocatalytic activity for degrading dyes through the photo‐Fenton reaction in the presence of hydrogen peroxide, endowing the NFM concurrently with effective nanofiltration performance and self‐cleaning capability. Moreover, the mineralized NFMs exhibit satisfactory stability under simultaneous filtration and photocatalysis processing, showing great potential in advanced wastewater treatment.
General Formation of Monodisperse IrM (M = Ni, Co, Fe) Bimetallic Nanoclusters as Bifunctional Electrocatalysts for Acidic Overall Water Splitting
Authors: Pi Yecan , Shao Qi , Wang Pengtang , Guo Jun , Huang Xiaoqing
Published: May 2017

The development of bifunctional electrocatalysts for overall water splitting in acidic media is vital for polymer electrolyte membrane (PEM) electrolyzers, but still full of obstacles. Here, highly efficient acidic overall water splitting is realized by utilizing ultrasmall, monodispersed Iridium (Ir)‐based nanoclusters (NCs) as the candidate, via a surfactant‐free, wet‐chemical, and large‐scalable strategy. Benefiting from the high specific surface area, clean surface, and strong binding between NCs and supports, the IrM NCs exhibit attractive activities and durability for both oxygen evolution reaction and hydrogen evolution reaction in acidic electrolytes, with IrNi NCs showing the best performance. More significantly, in the overall water splitting, IrNi NCs reach 10 mA cm−2 at a cell voltage of only 1.58 V in 0.5 m H2SO4 electrolyte, holding promises for potential implementation of PEM water electrolysis. This work opens a new avenue toward designing bifunctional “acidic stable” catalysts for efficient overall water splitting.
Deep‐Blue Phosphorescent Ir(III) Complexes with Light‐Harvesting Functional Moieties for Efficient Blue and White PhOLEDs in Solution‐Process
Authors: Sarada Ganguri , Cho Woosum , Maheshwaran Athithan , Sree Vijaya Gopalan , Park Ho‐Yeol , Gal Yeong‐Soon , Song Myungkwan , Jin Sung‐Ho
Published: May 2017

The photoluminescence (PL) efficiency of emitters is a key parameter to accomplish high electroluminescent performance in phosphorescent organic light‐emitting diodes (PhOLEDs). With the aim of enhancing the PL efficiency, this study designs deep‐blue emitting heteroleptic Ir(III) complexes (tBuCN‐FIrpic, tBuCN‐FIrpic‐OXD, and tBuCN‐FIrpic‐mCP) for solution‐processed PhOLEDs by covalently attaching the light‐harvesting functional moieties (mCP‐Me or OXD‐Me) to the control Ir(III) complex, tBuCN‐FIrpic. These Ir(III) complexes show similar deep‐blue emission peaks around 453, 480 nm (298 K) and 447, 477 nm (77 K) in chloroform. tBuCN‐FIrpic‐mCP demonstrates higher light‐harvesting efficiency (142%) than tBuCN‐FIrpic‐OXD (112%), relative to that of tBuCN‐FIrpic (100%), due to an efficient intramolecular energy transfer from the mCP group to the Ir(III) complex. Accordingly, the monochromatic PhOLEDs of tBuCN‐FIrpic‐mCP show higher external quantum efficiency (EQE) of 18.2% with one of the best blue coordinates (0.14, 0.18) in solution‐processing technology. Additionally, the two‐component (deep‐blue:yellow‐orange), single emitting layer, white PhOLED of tBuCN‐FIrpic‐mCP shows a maximum EQE of 20.6% and superior color quality (color rendering index (CRI) = 78, Commission Internationale de L'Eclairage (CIE) coordinates of (0.353, 0.352)) compared with the control device containing sky‐blue:yellow‐orange emitters (CRI = 60, CIE coordinates of (0.293, 0.395)) due to the good spectral coverage by the deep‐blue emitter.
Molecular Design of Mesoporous NiCo2O4 and NiCo2S4 with Sub‐Micrometer‐Polyhedron Architectures for Efficient Pseudocapacitive Energy Storage
Authors: Liu Yu , Wang Zhenbin , Zhong Yijun , Tade Moses , Zhou Wei , Shao Zongping
Published: May 2017

Spinel‐type NiCo2O4 (NCO) and NiCo2S4 (NCS) polyhedron architectures with sizes of 500–600 nm and rich mesopores with diameters of 1–2 nm are prepared facilely by the molecular design of Ni and Co into polyhedron‐shaped zeolitic imidazolate frameworks as solid precursors. Both as‐prepared NCO and NCS nanostructures exhibit excellent pseudocapacitance and stability as electrodes in supercapacitors. In particular, the exchange of O2− in the lattice of NCO with S2− obviously improves the electrochemical performance. NCS shows a highly attractive capacitance of 1296 F g−1 at a current density of 1 A g−1, ultrahigh rate capability with 93.2% capacitance retention at 10 A g−1, and excellent cycling stability with a capacitance retention of 94.5% after cycling at 1 A g−1 for 6000 times. The asymmetric supercapacitor with an NCS negative electrode and an active carbon positive electrode delivers a very attractive energy density of 44.8 Wh kg−1 at power density 794.5 W kg−1, and a favorable energy density of 37.7 Wh kg−1 is still achieved at a high power density of 7981.1 W kg−1. The specific mesoporous polyhedron architecture contributes significantly to the outstanding electrochemical performances of both NCO and NCS for capacitive energy storage.
Function Follows Form: Correlation between the Growth and Local Emission of Perovskite Structures and the Performance of Solar Cells
Authors: Dar M. Ibrahim , Hinderhofer Alexander , Jacopin Gwenole , Belova Valentina , Arora Neha , Zakeeruddin Shaik Mohammed , Schreiber Frank , Grätzel Michael
Published: May 2017

Understanding the relationship between the growth and local emission of hybrid perovskite structures and the performance of the devices based on them demands attention. This study investigates the local structural and emission features of CH3NH3PbI3, CH3NH3PbBr3, and CH(NH2)2PbBr3 perovskite films deposited under different yet optimized conditions using X‐ray scattering and cathodoluminescence spectroscopy, respectively. X‐ray scattering shows that a CH3NH3PbI3 film involving spin coating of CH3NH3I instead of dipping is composed of perovskite structures exhibiting a preferred orientation with [202] direction perpendicular to the surface plane. The device based on the CH3NH3PbI3 film composed of oriented crystals yields a relatively higher photovoltage. In the case of CH3NH3PbBr3, while the crystallinity decreases when the HBr solution is used in a single‐step method, the photovoltage enhancement from 1.1 to 1.46 V seems largely stemming from the morphological improvements, i.e., a better connection between the crystallites due to a higher nucleation density. Furthermore, a high photovoltage of 1.47 V obtained from CH(NH2)2PbBr3 devices could be attributed to the formation of perovskite films displaying uniform cathodoluminescence emission. The comparative analysis of the local structural, morphological, and emission characteristics of the different perovskite films supports the higher photovoltage yielded by the relatively better performing devices.
pH‐Triggered Pinpointed Cascading Charge‐Conversion and Redox‐Controlled Gene Release Design: Modularized Fabrication for Nonviral Gene Transfection
Authors: Jiang Qian , Nie Yu , Chen Xiaobing , He Yiyan , Yue Dong , Gu Zhongwei
Published: May 2017

Although pH and reduction responses are widely applied on gene and drug delivery system, the undefined molecule and disconnected response to corresponding transfection barriers still hamper their further application. Here, a multistage‐responsive lipopeptides polycation‐DNA nanoparticles (namely KR‐DC) as gene vector is designed, consisting of three functional modules. It provides the following outstanding “smart” characteristics: i) facile manufacture and ease to adjust ingredients for different conditions, ii) negatively charged surface to remain stable and increase biocompatibility in physiological environment, iii) pH‐triggered cascading charge‐conversion corresponding to tumor extracellular pH and endo/lysosomal pH, iv) the first stage of charge reversal for uptake enhancement at tumor site, v) the second stage of charge conversion for rapid endosomal escape, vi) the third stage of redox degradation aiming at DNA controlled release and nuclear entry, vii) cell‐penetrating peptides mimicking arginine‐rich periphery targeting to membrane penetration capacity improvement, and viii) lipid forming hydrophobic cavity for potential fat‐soluble drug encapsulation. Finally, KR‐DC nanoparticles achieve significantly enhanced in vitro transfection efficiency by almost four orders of magnitude in manual tumor environment with reduced side effects and satisfying gene expression in Hela xenograft tumor model in vivo.
Ultrafast and Highly Localized Microwave Heating in Carbon Nanotube Multilayer Thin Films
Authors: Haile Merid , Sweeney Charles B. , Lackey Blake A. , Sarwar Owais , Henderson Robert , Saed Mohammad A. , Green Micah J. , Grunlan Jaime C.
Published: May 2017

Carbon nanotubes have emerged as highly effective materials for microwave absorbing applications due to their high electrical conductivity, large aspect ratio, and high temperature stability against oxidation and corrosion. Ultrathin films are fabricated through layer‐by‐layer deposition of carbon nanotubes and poly(diallyldimethyl ammonium chloride) from aqueous suspensions under ambient conditions. The number of immersion cycles controls the assembled thickness of these coatings, which provides an effective means of precisely tailoring their electrical properties and thermal response to microwaves. Films of thickness below 200 nm are capable of heating to high temperatures when irradiated with low microwave power, reaching over 130 °C in 30 s, at less than 10 W forward power, and rapidly cooling when the power is removed. In contrast to metal thin films, the multilayer carbon nanotube films are active microwave absorbers over a wide range of thickness, making them interesting for applications such as electromagnetic interference shielding and microwave welding.
Tuning the Ferroelectric Properties of Trialkylbenzene‐1,3,5‐tricarboxamide (BTA)
Authors: Urbanaviciute Indre , Meng Xiao , Cornelissen Tim D. , Gorbunov Andrey V. , Bhattacharjee Subham , Sijbesma Rint P. , Kemerink Martijn
Published: May 2017

This study demonstrates how simple structural modification of a prototypical organic ferroelectric molecule can be used to tune its key ferroelectric properties. In particular, it is found that shortening the alkyl chain length of trialkylbenzene‐1,3,5‐tricarboxamide (BTA) from C18H37 to C6H13 causes an increase in depolarization activation energy (≈1.1–1.55 eV), coercive field (≈25–40 V µm−1), and remnant polarization (≈20–70 mC m−2). As the polarization enhancement far exceeds the geometrically expected factor, these observations are attributed to an increase in the intercolumnar interaction. The combination of the mentioned characteristics results in a record polarization retention time of close to three months at room temperature for capacitor devices of the material having the shortest alkyl chain. The long retention and the remnant polarization that is as high as that of P(VDF:TrFE) distinguish the BTA‐C6 material from other small molecular organic ferroelectrics and make it a perspective choice for applications that require cheap, flexible, and lightweight ferroelectrics.
Metal‐Organic Framework‐Derived Non‐Precious Metal Nanocatalysts for Oxygen Reduction Reaction
Authors: Fu Shaofang , Zhu Chengzhou , Song Junhua , Du Dan , Lin Yuehe
Published: May 2017

By virtue of diverse structures and tunable properties, metal‐organic frameworks (MOFs) have presented extensive applications including gas capture, energy storage, and catalysis. Recently, synthesis of MOFs and their derived nanomaterials provide an opportunity to obtain competent oxygen reduction reaction (ORR) electrocatalysts due to their large surface area, controllable composition and pore structure. This review starts with the introduction of MOFs and current challenges of ORR, followed by the discussion of MOF‐based non‐precious metal nanocatalysts (metal‐free and metal/metal oxide‐based carbonaceous materials) and their application in ORR electrocatalysis. Current issues in MOF‐derived ORR catalysts and some corresponding strategies in terms of composition and morphology to enhance their electrocatalytic performance are highlighted. In the last section, a perspective for future development of MOFs and their derivatives as catalysts for ORR is discussed.
Simulation of deformable preformed particle gel propagation in porous media
Authors: Wang Jing , Liu Hui‐Qing , Zhang Hong‐ling , Sepehrnoori Kamy
Published: May 2017

Preformed particle gel (PPG) treatment is a proven cost‐effective method for improving oil recovery. Although PPG system has a suspension‐like property, it has different propagation rules from the rigid particle suspension in porous media because of its good deformation property. In this study, an advanced phenomenological model of PPG propagation in porous media is presented. The model includes both PPG plugging and restarting behaviors. Log‐normal and normal distribution functions have been introduced in this model to calculate the PPG plugging probability. Power‐law equation is used to calculate the PPG restarting rate. This method can represent the commensurate relation between PPG and throat size. Then, the equations are solved numerically, using an explicit finite‐difference formulation in conjunction with a fourth‐order Runge‐Kutta method. The results match favorably with several laboratory experiments. Finally, the propagation rules and sensitivity analysis of PPG size, permeability and injection rate to propagation rules, and permeability reduction are performed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4628–4641, 2017
Ein photoschaltbarer Ligand zur Regulierung der Rezeptoraktivierung
Authors: Agnetta Luca , Kauk Michael , Canizal Maria Consuelo Alonso , Messerer Regina , Holzgrabe Ulrike , Hoffmann Carsten , Decker Michael
Published: May 2017

Über die Art und den zeitlichen Verlauf der Aktivierung von G‐Protein‐gekoppelten Rezeptoren (GPCRs), insbesondere der muskarinischen Acetylcholinrezeptoren (mACh‐ oder M‐Rezeptoren), ist trotz der enormen therapeutischen Relevanz von M‐Rezeptoren und GPCRs wenig bekannt. In der vorliegenden Arbeit haben wir deshalb einen dualsteren Liganden eingesetzt, der sowohl mit der orthosteren Bindungsstelle des Rezeptors, d. h. derjenigen des Neurotransmitters, als auch mit einer allosteren Bindungsstelle interagiert, wobei synthetisch eine photoschaltbare (photochrome) Azobenzoleinheit eingebaut wurde. Wir haben die photophysikalischen Eigenschaften des BQCAAI benannten Liganden charakterisiert und seine Einsetzbarkeit als pharmakologisches Werkzeug mit einem Satz von FRET‐Techniken am M1‐Rezeptor untersucht. BQCAAI stellt den ersten photoschaltbaren dualsteren Liganden dar, und seine Aktivität kann durch Licht reguliert werden. Wir haben BQCAAI eingesetzt, um den zeitlichen Ablauf verschiedener Prozesse der Rezeptoraktivierung zu untersuchen.
Native Mass Spectrometry from Common Buffers with Salts That Mimic the Extracellular Environment
Authors: Susa Anna C. , Xia Zijie , Williams Evan R.
Published: May 2017

Nonvolatile salts are essential for the structures and functions of many proteins and protein complexes but can severely degrade performance of native mass spectrometry by adducting to protein and protein complex ions, thereby reducing sensitivity and mass measuring accuracy. Small nanoelectrospray emitters are used to form protein and protein complex ions directly from high‐ionic‐strength (>150 mm) nonvolatile buffers with salts that mimic the extracellular environment. Charge‐state distributions are not obtained for proteins and protein complexes from six commonly used nonvolatile buffers and ≥150 mm Na+ with conventionally sized nanoelectrospray emitter tips but are resolved with 0.5 μm tips. This method enables mass measurements of proteins and protein complexes directly from a variety of commonly used buffers with high concentrations of nonvolatile salts and eliminates the need to buffer exchange into volatile ammonium buffers traditionally used in native mass spectrometry.
Bioluminescent Antibodies for Point‐of‐Care Diagnostics
Authors: Xue Lin , Yu Qiuliyang , Griss Rudolf , Schena Alberto , Johnsson Kai
Published: May 2017

We introduce a general method to transform antibodies into ratiometric, bioluminescent sensor proteins for the no‐wash quantification of analytes. Our approach is based on the genetic fusion of antibody fragments to NanoLuc luciferase and SNAP‐tag, the latter being labeled with a synthetic fluorescent competitor of the antigen. Binding of the antigen, here synthetic drugs, by the sensor displaces the tethered fluorescent competitor from the antibody and disrupts bioluminescent resonance energy transfer (BRET) between the luciferase and fluorophore. The semisynthetic sensors display a tunable response range (submicromolar to submillimolar) and large dynamic range (ΔRmax>500 %), and they permit the quantification of analytes through spotting of the samples onto paper followed by analysis with a digital camera.
Mangan‐katalysierte nachhaltige Synthese von Pyrrolen aus Alkoholen und Aminoalkoholen
Authors: Kallmeier Fabian , Dudziec Beata , Irrgang Torsten , Kempe Rhett
Published: May 2017

Die Entwicklung von Reaktionen, die Alkohole in wichtige chemische Verbindungen umwandeln, sichert die fossilen Kohlenstoffressourcen, da Alkohole aus unverdaulicher Biomasse wie Lignocellulose gewonnen werden können. Die Erhaltung der seltenen Edelmetalle ist von gleicher Bedeutung, und ihre Ersetzung durch reichlich vorhandene Übergangsmetalle wie Mn, Fe oder Co (Basismetalle oder mittlere 3d‐Metalle) in Schlüsseltechnologien wie der Katalyse ist eine vielversprechende Option. Hier wird die erste Basismetall‐katalysierte Synthese von Pyrrolverbindungen aus Alkoholen und Aminoalkoholen vorgestellt. Die effizientesten Katalysatoren sind PN5P‐Ligand‐stabilisierte Mn‐Komplexe. Verwandte Fe‐ und Co‐Komplexe sind inaktiv. Die unter milden Bedingungen ablaufende Reaktion mit Katalysatorbeladungen von nur 0.5 Mol‐% hat ein breites Spektrum und ist gut verträglich mit funktionellen Gruppen. Die Ergebnisse können andere dazu inspirieren, Mn‐Katalysatoren als Ir‐ oder Ru‐Ersatz in anspruchsvollen Dehydrierungskatalysen zu verwenden.
Enantioselective Borylation of Aromatic C−H Bonds with Chiral Dinitrogen Ligands
Authors: Su Bo , Zhou Tai‐Gang , Xu Pei‐Lin , Shi Zhang‐Jie , Hartwig John F.
Published: May 2017

The borylation of C−H bonds catalyzed by transition metals has been investigated extensively in the past two decades, but no iridium‐catalyzed enantioselective borylation of C−H bonds has been reported. We report a set of iridium‐catalyzed enantioselective borylations of aromatic C−H bonds. This reaction relies on a set of newly developed chiral quinolyl oxazoline ligands. This process proceeds under mild conditions with good to excellent enantioselectivity, and the borylated products can be converted to enantioenriched derivatives containing new C−O, C−C, C−Cl, or C−Br bonds.
Stereoselective Synthesis of Tetrasubstituted Alkenes via a Cp*CoIII‐Catalyzed C−H Alkenylation/Directing Group Migration Sequence
Authors: Ikemoto Hideya , Tanaka Ryo , Sakata Ken , Kanai Motomu , Yoshino Tatsuhiko , Matsunaga Shigeki
Published: May 2017

A highly atom economical and stereoselective synthesis of tetrasubstituted α,β‐unsaturated amides was achieved by a Cp*CoIII‐catalyzed C−H alkenylation/directing group migration sequence. A carbamoyl directing group, which is typically removed after C−H functionalization, worked as an internal acylating agent and migrated onto the alkene moiety of the product. The directing group migration was realized with the Cp*CoIII catalyst, while a related Cp*RhIII catalyst did not promote the migration process. The product was further converted into two types of tricyclic compounds, one of which had fluorescent properties.
The Structural Fate of Individual Multicomponent Metal‐Oxide Nanoparticles in Polymer Nanoreactors
Authors: Du Jingshan S. , Chen Peng‐Cheng , Meckes Brian , Xie Zhuang , Zhu Jinghan , Liu Yuan , Dravid Vinayak P. , Mirkin Chad A.
Published: May 2017

Multicomponent nanoparticles can be synthesized with either homogeneous or phase‐segregated architectures depending on the synthesis conditions and elements incorporated. To understand the parameters that determine their structural fate, multicomponent metal‐oxide nanoparticles consisting of combinations of Co, Ni, and Cu were synthesized by using scanning probe block copolymer lithography and characterized using correlated electron microscopy. These studies revealed that the miscibility, ratio of the metallic components, and the synthesis temperature determine the crystal structure and architecture of the nanoparticles. A Co‐Ni‐O system forms a rock salt structure largely owing to the miscibility of CoO and NiO, while Cu‐Ni‐O, which has large miscibility gaps, forms either homogeneous oxides, heterojunctions, or alloys depending on the annealing temperature and composition. Moreover, a higher‐ordered structure, Co‐Ni‐Cu‐O, was found to follow the behavior of lower ordered systems.
Triboluminescence of Lanthanide Coordination Polymers with Face‐to‐Face Arranged Substituents
Authors: Hirai Yuichi , Nakanishi Takayuki , Kitagawa Yuichi , Fushimi Koji , Seki Tomohiro , Ito Hajime , Hasegawa Yasuchika
Published: May 2017

Luminescence upon the grinding of solid materials (triboluminescence, TL) has long been a puzzling phenomenon in natural science and has also attracted attention because of its broad application in optics. It has been generally considered that the TL spectra exhibit similar profiles as those of photoluminescence (PL), although they occur from distinct stimuli. Herein, we describe for the first time a large spectral difference between these two physical phenomena using lanthanideIII coordination polymers with efficient TL and PL properties. They are composed of emission centers (TbIII and EuIII ions), antenna (hexafluoroacetylacetonate=hfa), and bridging ligands (2,5‐bis(diphenylphosphoryl)furan=dpf). The emission color upon grinding (yellow TL) is clearly different from that upon UV irradiation (reddish‐orange PL) in TbIII/EuIII‐mixed coordination polymers [Tb,Eu(hfa)3(dpf)]n (Tb/Eu=1). The results directly indicate the discrete excitation processes of PL and TL.
Construction of the Benzomesembrine Skeleton: Palladium(0)‐Catalyzed Intermolecular Arylative Dearomatization of α‐Naphthols and Subsequent Aza‐Michael Reaction
Authors: Xu Ren‐Qi , Gu Qing , You Shu‐Li
Published: May 2017

A novel palladium(0)‐catalyzed intermolecular arylative dearomatization of α‐naphthols and subsequent aza‐Michael reaction is described. Two adjacent stereocenters were constructed efficiently through consecutive arylative dearomatization and Michael addition reactions. By utilizing this method, structurally diverse benzomesembrine derivatives were synthesized with excellent yields and chemoselectivity. The benzomesembrine products were shown to undergo versatile functional‐group transformations.
Tricyanmethan und sein Ketenimin‐Tautomer: Bildung aus verschiedenen Vorstufen sowie Analyse in Lösung, in einer Argonmatrix und im Einkristall
Authors: Banert Klaus , Chityala Madhu , Hagedorn Manfred , Beckers Helmut , Stüker Tony , Riedel Sebastian , Rüffer Tobias , Lang Heinrich
Published: May 2017

Lösungen von Azidomethylidenmalononitril wurden bei tiefer Temperatur photolysiert, um das entsprechende 2H‐Azirin und Tricyanmethan zu bilden, was durch Tieftemperatur‐NMR‐Spektroskopie analysiert wurde. Das letztgenannte Produkt wurde auch nach kurzer Thermolyse einer Lösung der Azid‐Vorstufe beobachtet, während die Bestrahlung des in einer Argonmatrix isolierten Azids nicht zum Tricyanmethan, sondern erstmals zum zweifelsfreien Nachweis des tautomeren Ketenimins durch IR‐Spektroskopie führte. Wenn die lange bekannte, grünliche “aquoethereal” Phase, die aus Kaliumtricyanmethanid, verdünnter Schwefelsäure und Diethylether entsteht, rasch eingedampft und sublimiert wurde, resultierte statt des früher proklamierten Ketenimin‐Tautomers eine Mischung aus Hydroniumtricyanmethanid und Tricyanmethan. Unter speziellen Bedingungen ergab die Sublimation Einkristalle des Tricyanmethans, was die Analyse der Molekülstruktur mithilfe der Röntgenbeugung ermöglichte.
Substrate‐Specific Amino Acid Sensing Using a Molecular d/ l‐Cysteine Probe for Comprehensive Stereochemical Analysis in Aqueous Solution
Authors: Thanzeel F. Yushra , Wolf Christian
Published: May 2017

The appearance of d‐amino acids in mammals and humans has important implications in the life sciences. d/l‐Amino acid mixtures play a key role in human physiology and pathology; thus, the introduction of artificial receptors for the real‐time quantification of both the concentration and d/l composition of amino acids is very promising for the study of biological processes and for the diagnosis and treatment of diseases. We now report a sensing assay that is compatible with aqueous solutions and allows fast determination of the absolute configuration, enantiomeric composition, and overall amount of cysteine at micromolar concentrations. The method relies on fast UV and CD measurements, which provide accurate stereochemical information on samples covering a wide concentration range and drastically different d/l‐cysteine ratios in simulated body fluids. Competition experiments show that other amino acids and biothiols do not interfere with the cysteine‐targeted sensing.
A Photoswitchable Dualsteric Ligand Controlling Receptor Efficacy
Authors: Agnetta Luca , Kauk Michael , Canizal Maria Consuelo Alonso , Messerer Regina , Holzgrabe Ulrike , Hoffmann Carsten , Decker Michael
Published: May 2017

The investigation of the mode and time course of the activation of G‐protein‐coupled receptors (GPCRs), in particular muscarinic acetylcholine (mACh or M) receptors, is still in its infancy despite the tremendous therapeutic relevance of M receptors and GPCRs in general. We herein made use of a dualsteric ligand that can concomitantly interact with the orthosteric, that is, the neurotransmitter, binding site and an allosteric one. We synthetically incorporated a photoswitchable (photochromic) azobenzene moiety. We characterized the photophysical properties of this ligand called BQCAAI and investigated its applicability as a pharmacological tool compound with a set of FRET techniques at the M1 receptor. BQCAAI proved to be an unprecedented molecular tool; it is the first photoswitchable dualsteric ligand, and its activity can be regulated by light. We also applied BQCCAI to investigate the time course of several receptor activation processes.
AibA/AibB Induces an Intramolecular Decarboxylation in Isovalerate Biosynthesis by Myxococcus xanthus
Authors: Bock Tobias , Luxenburger Eva , Hoffmann Judith , Schütza Vlad , Feiler Christian , Müller Rolf , Blankenfeldt Wulf
Published: May 2017

Isovaleryl coenzyme A (IV‐CoA) is an important precursor for iso‐fatty acids and lipids. It acts in the development of myxobacteria, which can produce this compound from acetyl‐CoA through alternative IV‐CoA biosynthesis (aib). A central reaction of aib is catalyzed by AibA/AibB, which acts as a cofactor‐free decarboxylase despite belonging to the family of CoA‐transferases. We developed an efficient expression system for AibA/AibB that allowed the determination of high‐resolution crystal structures in complex with different ligands. Through mutational studies, we show that an active‐site cysteine previously proposed to be involved in decarboxylation is not required for activity. Instead, AibA/AibB seems to induce an intramolecular decarboxylation by binding its substrate in a hydrophobic cavity and forcing it into a bent conformation. Our study opens opportunities for synthetic biology studies, since AibA/AibB may be suitable for the production of isobutene, a precursor of biofuels and chemicals.
Synthesis and Trapping of Iminoboranes by M=B/C=N Bond Metathesis
Authors: Nutz Marco , Borthakur Bitupon , Dewhurst Rian D. , Deißenberger Andrea , Dellermann Theresa , Schäfer Marius , Krummenacher Ivo , Phukan Ashwini K. , Braunschweig Holger
Published: May 2017

Although the metathesis of metal–boron double bonds with elemental chalcogenides is an established process, no similar reactivity has been observed with element–nitrogen bonds. Such a reaction would provide a new route to iminoborane compounds (RB≡NR′), which have recently experienced renewed synthetic interest. Herein, we present the first observation of M=B/C=N metathesis reactions, which led to the isolation of a stable iminoborane in addition to further iminoborane cycloaddition products.
Tricyanomethane and Its Ketenimine Tautomer: Generation from Different Precursors and Analysis in Solution, Argon Matrix, and as a Single Crystal
Authors: Banert Klaus , Chityala Madhu , Hagedorn Manfred , Beckers Helmut , Stüker Tony , Riedel Sebastian , Rüffer Tobias , Lang Heinrich
Published: May 2017

Solutions of azidomethylidenemalononitrile were photolyzed at low temperatures to produce the corresponding 2H‐azirine and tricyanomethane, which were analyzed by low‐temperature NMR spectroscopy. The latter product was also observed after short thermolysis of the azide precursor in solution whereas irradiation of the azide isolated in an argon matrix did not lead to tricyanomethane, but to unequivocal detection of the tautomeric ketenimine by IR spectroscopy for the first time. When the long‐known “aquoethereal” greenish phase generated from potassium tricyanomethanide, dilute sulfuric acid, and diethyl ether was rapidly evaporated and sublimed, a mixture of hydronium tricyanomethanide and tricyanomethane was formed instead of the previously claimed ketenimine tautomer. Under special conditions of sublimation, single crystals of tricyanomethane could be isolated, which enabled the analysis of the molecular structure by X‐ray diffraction.