bluuebunny/crossref_metadata_2025_split huggingface dataset:
How important are the alpha‐proton relative drift and the electron heat flux for the proton heating of the solar wind in the inner heliosphere?
Authors: Borovsky Joseph E. , Gary S. Peter 
Published: June 2014

AbstractThis report explores the feasibility of explaining the observed proton heating in the inner heliosphere (1) by tapping the field‐aligned relative drift between alpha particles and protons in the solar wind plasma and (2) by tapping the strahl‐electron heat flux from the Sun. The observed reduction of the alpha‐proton drift kinetic energy from 0.3 to 1 AU and the observed reduction of electron heat flux from 0.3 to 1 AU are each about half of the energy needed to account for the observed heating of protons from 0.3 to 1 AU. A mechanism is identified to transfer the free energy of the alpha‐proton relative drift into proton thermal energy: the alpha‐proton magnetosonic instability. A mechanism is identified to transfer kinetic energy from the strahl‐electron heat flux into proton thermal energy: weak double layers. At the current state of knowledge, the plausibility of heating the solar wind protons via the alpha‐proton magnetosonic instability is high. The properties of the weak double layers that have been observed in the solar wind are not well known; more data analysis and plasma simulations are needed before the plausibility of heating the solar wind protons by the double‐layer mechanism can be evaluated.
Pulse properties of terrestrial gamma‐ray flashes detected by the Fermi Gamma‐Ray Burst Monitor
Authors: Foley S. , Fitzpatrick G. , Briggs M. S. , Connaughton V. , Tierney D. , McBreen S. , Dwyer J. R. , Chaplin V. L. , Bhat P. N. , Byrne D. , Cramer E. , Fishman G. J. , Xiong S. , Greiner J. , Kippen R. M. , Meegan C. A. , Paciesas W. S. , Preece R. D. , von Kienlin A. , Wilson‐Hodge C. 
Published: June 2014

AbstractThe Gamma‐ray Burst Monitor (GBM) on board the Fermi Gamma‐ray Space Telescope has triggered on over 300 terrestrial gamma‐ray flashes (TGFs) since its launch in June 2008. With 14 detectors, GBM collects on average ∼100 counts per triggered TGF, enabling unprecedented studies of the time profiles of TGFs. Here we present the first rigorous analysis of the temporal properties of a large sample of TGFs (278), including the distributions of the rise and fall times of the individual pulses and their durations. A variety of time profiles are observed with 19% of TGFs having multiple pulses separated in time and 31 clear cases of partially overlapping pulses. The effect of instrumental dead time and pulse pileup on the temporal properties are also presented. As the observed gamma ray pulse structure is representative of the electron flux at the source, TGF pulse parameters are critical to distinguish between relativistic feedback discharge and lightning leader models. We show that at least 67% of TGFs at satellite altitudes are significantly asymmetric. For the asymmetric pulses, the rise times are almost always shorter than the fall times. Those which are not are consistent with statistical fluctuations. The median rise time for asymmetric pulses is ∼3 times shorter than for symmetric pulses while their fall times are comparable. The asymmetric shapes observed are consistent with the relativistic feedback discharge model when Compton scattering of photons between the source and Fermi is included, and instrumental effects are taken into account.
Extent of ECH wave emissions in the Earth's magnetotail
Authors: Zhang Xiaojia , Angelopoulos Vassilis , Ni Binbin , Thorne Richard M. , Horne Richard B. 
Published: June 2014

AbstractThe exact role of electrostatic electron cyclotron harmonic (ECH) waves in driving diffuse aurora has been controversial for many years. Using THEMIS observations from five magnetotail seasons, we investigate the occurrence rate distribution of ECH waves and the extent of individual wave intensifications under various plasma sheet conditions. Both are critical for modeling these waves' contributions to electron scattering and to diffuse auroral emissions. Single‐spacecraft data analysis shows that ECH waves occur frequently in the midnight and postmidnight magnetotail and that their occurrence rates decrease with increasing radial distance from Earth. More than 50% of ECH wave events (continuous intervals of wave activity) occur during local plasma sheet activations, evidenced by energetic electron injections and dipolarization fronts. Excluding ECH wave emissions concurrent with such local plasma sheet activations (known to peak in occurrence rate near premidnight), we find that quiet plasma sheet ECH wave emissions exhibit preference for dawn. This preference suggests a close relationship between these waves and the drift paths of injected electrons. Dual‐spacecraft data analysis shows that the Z‐extent is ~0.5 RE, the Y‐extent is ~2 RE, and the X‐extent is at least 4 RE. During locally quiet plasma sheet conditions, ECH waves exhibit a smaller Z‐ and X‐extent, but the Y‐extent is similar during all the conditions. In order to investigate the mechanism leading to the different Z‐extents under various plasma sheet conditions, we use ray tracing to model the wave power distribution as a function of distance from the neutral sheet. We find a linear correlation between the wave Z‐extent and field line curvature radius (Rc). A Z‐extent of ~0.2 RE (consistent with observations) corresponds to Rc~0.9 RE. Our results suggest that ECH intensification following dipolarizing flux bundles is in part due to increased Rc, which enables intensification to higher amplitudes over a larger volume, explaining the increased occurrence rate and extent of active‐time wave events.
Effects of heterogeneous soil‐water diffusivity on vegetation pattern formation
Authors: Yizhaq H. , Sela S. , Svoray T. , Assouline S. , Bel G. 
Published: June 2014

AbstractMany mathematical models have been proposed to explain the emergence of vegetation patterns in arid and semiarid environments, but only a few of them take into account the heterogeneity in the system properties. Here we present a rigorous study of the effects of heterogeneous soil‐water diffusivity on vegetation patterns, using two mathematical models. The two models differ in the pattern‐forming feedback that they capture; one model captures the infiltration contrast between vegetated and bare‐soil domains, whereas the other model captures the increased growth rate of denser vegetation due to an enhanced ability to extract water from the soil. In both models, the most significant effect of the heterogeneity on the soil‐water diffusivity is the increased durability of patterned vegetation to a reduced precipitation rate. An additional effect is that the heterogeneity makes the desertification process, namely, the transition from a spotted vegetation pattern to a bare‐soil state, more gradual than in the homogeneous system. Our findings suggest that the heterogeneity cannot be neglected in the study of critical transitions in heterogeneous ecosystems and, particularly, in the study of the desertification process due to climate changes or anthropogenic disturbances.
Design of Superhydrophobic Porous Coordination Polymers through the Introduction of External Surface Corrugation by the Use of an Aromatic Hydrocarbon Building Unit
Authors: Rao Koya Prabhakara , Higuchi Masakazu , Sumida Kenji , Furukawa Shuhei , Duan Jingui , Kitagawa Susumu 
Published: June 2014

AbstractWe demonstrate a new approach to superhydrophobic porous coordination polymers by incorporating an anisotropic crystal morphology featuring a predominant surface that is highly corrugated and terminated by aromatic hydrocarbon moieties. The resulting low‐energy surface provides particularly promising hydrophobic properties without the need for postsynthetic modifications or surface processing that would block the porosity of the framework. Consequently, hydrophobic organic molecules and water vapor are able to penetrate the surface and be densely accommodated within the pores, whereas bulk water is repelled as a result of the exterior surface corrugation derived from the aromatic surface groups. This study provides a new strategy for the design and development of superhydrophobic porous materials.
Aromatic Versus Heteroradialene Character in Extended Thiophloroglucinol Ligands and their Trinuclear Nickel(II) Complexes
Authors: Feldscher Bastian , Stammler Anja , Bögge Hartmut , Glaser Thorsten 
Published: June 2014

AbstractExtended phloroglucinol ligands and complexes are best described as nonaromatic heteroradialenes. Herein, the electronic structures of extended thiophloroglucinol ligands and their NiII3 complexes are evaluated by comparison to their phloroglucinol analogs by means of NMR, FTIR, UV/Vis, and structural parameters. To provide a full set of compounds for this comparison of S versus O substitution, a new triplesalen ligand, its NiII3 complex, and a new thiophloroglucinol were synthesized. 1H and 15N NMR chemical shifts and coupling constants prove that the thiophloroglucinol ligands exist as the N‐protonated and not the O‐protonated tautomer. 13C and 15N NMR chemical shifts and structural parameters further demonstrated that the extended thiophloroglucinol ligands must be described with a predominant thione‐enamine (heteroradialene) character despite the participation of a CS double bond. In the NiII3 complexes, this heteroradialene character is reduced but still predominant.
An overview to understand the role of PE_PGRS family proteins in Mycobacterium tuberculosisH37Rv and their potential as new drug targets
Authors: Meena Laxman S. 
Published: June 2014

AbstractTuberculosis has long been the scourge of humanity, claiming millions of lives. The family of PE_PGRS gene has been attributed to the Mycobacterium tuberculosis pathogenesis over the past few decades. The gene of PE_PGRS family proteins are most often clustered in a region of the genome often as overlapping genes and role in cell surface markers, adhesion and invasion of defense cells of the host (macrophage and dendritic cells). The proline–glutamic acid (PE) domain is responsible for the cellular localization of these proteins on bacterial cells. This gene family shows immense genetic variability in terms of multiple insertion–deletions and single‐nucleotide polymorphisms as seen in PE_PGRS9, PE_PGRS17, PE_PGRS18, and PE_PGRS33. In spite of variability, there are indications of shared epitopes in these proteins. Few of these gene sequences that have been studied from evolutionary perspective show indication of positive selection and also landmarks of recent evolutionary events. Many of these proteins show calcium‐binding motifs and consequently seen to be responsible in inhibition of phagolysosome formation via a calmodulin‐kinase‐dependent pathway. A number of PE_PGRS genes were tested for its expression with different growth conditions in vitro and in vivo, among which the contrast in expressivity was seen vividly in PE_PGRS16 (upregulated) and PE_PGRS26 (downregulated) in bacteria persisting in macrophages. Similarly, PE_PGRS33 has been indicated in macrophagial necrosis by a tumor necrosis factor‐α‐induced pathway. These PE_PGRS family genes may be an interesting subject for research and development. Their fibronectin‐binding and calcium‐binding property may be strongly implicated in immunopathogenesis of virulent M. tuberculosis strain. In this review, an attempt has been made to evaluate and present data for better understanding of in vivo pathogen functions, for understanding the physiological significance of PE_PGRS gene family, and their potential as new drug targets.
Determination of vitamin B6 using an optimized novel TCPO–indolizine–H2O2 chemiluminescence system
Authors: Chaichi M. J. , Ehsani M. , Asghari S. , Behboodi V. 
Published: June 2014

ABSTRACTIndolizine derivatives are of great interest as fluorescent emitters for peroxyoxalate chemiluminescence. The reaction of peroxyoxalates such as bis‐(2,4,6‐trichlorophenyl) oxalate (TCPO) with H2O2 can transfer energy to fluorescer via the formation of dioxetanedione intermediate. Four indolizine derivatives were used as a novel fluorescer in the chemiluminescence (CL) systems in this study. The relationship between CL intensity and the concentration of fluorescer, peroxyoxalate, sodium salicylate and hydrogen peroxide was investigated. Optimum conditions were obtained for four fluorescers and it was found that the indolizine can be used as an efficient green fluorescence emitter. Vitamin B6 induces a sharp decrease in the CL intensity of the TCPO–hydrogen peroxide–sodium salicylate system. A simple, rapid and sensitive CL method for the determination of vitamin B6 has been developed. The results showed a linear relationship between vitamin B6 concentration and peroxyoxalate CL intensity in the range 7.0 × 10−8–1.0 × 10−4. A detection limit of 2.3 × 10−8 M and relative standard deviation (RSD) of < 4.5% were obtained. Copyright © 2014 John Wiley & Sons, Ltd.
Genetic Encoding of Caged Cysteine and Caged Homocysteine in Bacterial and Mammalian Cells
Authors: Uprety Rajendra , Luo Ji , Liu Jihe , Naro Yuta , Samanta Subhas , Deiters Alexander 
Published: June 2014

AbstractWe report the genetic incorporation of caged cysteine and caged homocysteine into proteins in bacterial and mammalian cells. The genetic code of these cells was expanded with an engineered pyrrolysine tRNA/tRNA synthetase pair that accepts both light‐activatable amino acids as substrates. Incorporation was validated by reporter assays, western blots, and mass spectrometry, and differences in incorporation efficiency were explained by molecular modeling of synthetase–amino acid interactions. As a proof‐of‐principle application, the genetic replacement of an active‐site cysteine residue with a caged cysteine residue in Renilla luciferase led to a complete loss of enzyme activity; however, upon brief exposure to UV light, a >150‐fold increase in enzymatic activity was observed, thus showcasing the applicability of the caged cysteine in live human cells. A simultaneously conducted genetic replacement with homocysteine yielded an enzyme with greatly reduced activity, thereby demonstrating the precise probing of a protein active site. These discoveries provide a new tool for the optochemical control of protein function in mammalian cells and expand the set of genetically encoded unnatural amino acids.
Using Chemistry to Investigate the Molecular Consequences of Protein Ubiquitylation
Authors: Abeywardana Tharindumala , Pratt Matthew R. 
Published: June 2014

AbstractChemistry has long played an indispensable role in biological discovery through the synthesis of homogeneous, structurally defined material. With continuing advances in the area of synthetic protein chemistry, chemists are able to prepare increasingly large and complex proteins that have enabled key biochemical experiments. Here, we describe some of the chemical methods that have been applied to the synthesis of ubiquitylated proteins, as ubiquitylation is a crucial post‐translational modification that mediates a variety of important biological effects on substrate proteins.
Prevalence and predictors of carotid artery stenosis in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation
Authors: Steinvil Arie , Leshem‐Rubinow Eran , Abramowitz Yigal , Shacham Yacov , Arbel Yaron , Banai Shmuel , Bornstein Natan M. , Finkelstein Ariel , Halkin Amir 
Published: June 2014

ObjectivesOur aim was to analyze the prevalence and predictors of Carotid artery stenosis (CAS) in patients undergoing transcatheter aortic valve implantation (TAVI).BackgroundCAS is associated with the risk of periprocedural stroke in patients undergoing cardiac surgery. However, little is known about the prevalence of and clinical significance of CAS in the setting of TAVI.MethodsConsecutive patients undergoing a carotid Doppler study the day before TAVI were followed prospectively. CAS was defined in accordance with current practice guidelines. Logistic regression models were used to identify independent correlates of CAS.ResultsThe study included 171 patients (age 82 ± 6, male gender 47%). Carotid atherosclerosis (CA, defined as any carotid plaque) was present in 164 (96%) of patients, and CAS (peak systolic velocity [PSV] ≥ 125 cm/sec; ≥50% diameter stenosis) in 57 (33%) patients. Severe CAS (PSV ≥ 230 cm/sec; ≥70% stenosis, or near occlusion) was found in 15 (9%) patients. By multivariate analysis, smoking and a higher Euroscore independently predicted the presence of CAS. Patients in the present TAVI cohort had a significantly higher prevalence of both unilateral and bilateral CAS ≥ 50% than those in a previously reported cohort (n = 494 patients, age ≥ 70) undergoing clinically driven coronary angiography (33% vs. 20%, OR = 1.9, P = 0.001; and, 13% vs. 6%, OR = 2.3, P = 0.003, respectively). CAS was not independently associated with 30‐day mortality or stroke rates.ConclusionsThe prevalence of CAS in patients undergoing TAVI is high, exceeding that observed in patients undergoing catheterization for coronary indications. The impact of CAS on clinical outcomes following TAVI merits further research. © 2014 Wiley Periodicals, Inc.
Neo‐annulus: A reference plane in a surgical heart valve to facilitate a valve‐in‐valve procedure
Authors: Bapat Vinayak , Adams Benjamin , Attia Rizwan , Noorani Alia , Thomas Martyn 
Published: June 2014

ObjectivesTo determine the level of the narrowest plane (neo‐annulus) of a surgical heart valve (SHV), which could be used for sizing and securing a transcatheter heart valve (THV) during a valve‐in‐valve (VIV) procedure and define its relationship with the fluoroscopic markers of the SHV.BackgroundIn the native aortic valve, the aortic annulus is used as a reference plane for sizing and deployment of THV as it provides the narrowest dimension to securely anchor the THV. However, the reference level for different models of SHV that are currently treated by a VIV procedure remains unknown.MethodsWe studied 13 aortic SHVs from all major heart valve manufacturers (labeled size 21, 22, or 23). A 26cc valvuloplasty balloon was inflated with contrast within each SHV under fluoroscopy to achieve a ‘waist’. The level of the ‘waist’ was compared with the SHV and its fluoroscopic markers to identify the level of the neo‐annulus.ResultsIn all SHVs tested, the balloon ‘waist’ or ‘neo‐annulus’ was at the level of the sewing ring. When the fluoroscopic marker of the SHV was the sewing ring, the level of the neo‐annulus was also at that level, irrespective of supra‐annular or intra‐annular design. However, when the fluoroscopic marker was the stent frame, the relationship between the fluoroscopic marker and the level of the neo‐annulus was different for supra‐annular and intra‐annular designs. This correlation was not possible in two models of SHV as neither the stent nor the sewing ring was radio‐opaque.ConclusionsWe have demonstrated that the narrowest portion of all SHVs is at the level of its sewing ring, which can be identified fluoroscopically and should be used as a reference level during a VIV procedure. © 2014 Wiley Periodicals, Inc.
Competitive Reaction Pathways for the Gas‐Phase Reactivity of [Me2AlNH2]3
Authors: Davydova Elena I. , Frenking Gernot , Timoshkin Alexey Y. 
Published: June 2014

AbstractReaction energy profiles for [Me2AlNH2]3 have been computationally explored by using density functional theory. Both intra‐ and intermolecular methane elimination reactions, as well as AlN bond‐breaking pathways, were considered. The results show that the energy required for AlN bond breaking in cyclic [Me2AlNH2]3 is of the same order of magnitude as the activation energies for the first (limiting) step of methane elimination (for both mono‐ and bimolecular mechanisms). Thus, dissociative and associative reaction pathways are competitive. Low‐temperature/high‐pressure conditions will favor the bimolecular pathway, whereas at high temperatures, either intramolecular methane elimination or AlN bond‐breaking dissociative pathways will be operational.
Selective Hydrodeoxygenation of Cyclic Vicinal Diols to Cyclic Alcohols over Tungsten Oxide–Palladium Catalysts
Authors: Amada Yasushi , Ota Nobuhiko , Tamura Masazumi , Nakagawa Yoshinao , Tomishige Keiichi 
Published: June 2014

AbstractHydrodeoxygenation of cyclic vicinal diols such as 1,4‐anhydroerythritol was conducted over catalysts containing both a noble metal and a group 5–7 transition‐metal oxide. The combination of Pd and WOx allowed the removal of one of the two OH groups selectively. 3‐Hydroxytetrahydrofuran was obtained from 1,4‐anhydroerythritol in 72 and 74 % yield over WOx–Pd/C and WOx–Pd/ZrO2, respectively. The WOx–Pd/ZrO2 catalyst was reusable without significant loss of activity if the catalyst was calcined as a method of regeneration. Characterization of WOx–Pd/C with temperature‐programmed reduction, X‐ray diffraction, and transmission electron microscopy/energy‐dispersive X‐ray spectroscopy suggested that Pd metal particles approximately 9 nm in size were formed on amorphous tungsten oxide particles. A reaction mechanism was proposed on the basis of kinetics, reaction results with tungsten oxides under an atmosphere of Ar, and density functional theory calculations. A tetravalent tungsten center (WIV) was formed by reduction of WO3 with the Pd catalyst and H2, and this center served as the reductant for partial hydrodeoxygenation.
Promising Aquivion Composite Membranes based on Fluoroalkyl Zirconium Phosphate for Fuel Cell Applications
Authors: Donnadio Anna , Pica Monica , Subianto Surya , Jones Deborah J. , Cojocaru Paula , Casciola Mario 
Published: June 2014

AbstractLayered zirconium phosphate (ZP) that bears fluorinated alkyl chains bonded covalently to the layers (ZPR) was used as a nanofiller in membranes based on a short‐side‐chain perfluorosulfonic acid (PFSA) to mechanically reinforce the PFSA hydrophobic component. Compared to the pristine PFSA, membranes with a ZPR loading up to 30 wt % show enhanced mechanical properties, and the largest improvement of elastic modulus (E) and yield stress (σY) are observed for the 10 wt % ZPR membrane: ΔE/E up to 90 % and ΔσY/σY up 70 % at 70 °C and 80 % relative humidity (RH). In the RH range 50–95 %, the in‐plane conductivity of the composite membranes reaches 0.43 S cm−1 for 10 wt % ZPR at 110 °C and is on average 30 % higher than the conductivity of the pristine PFSA. The 10 wt % ZPR membrane is as hydrated as the neat PFSA membrane at 50 % RH but becomes progressively less hydrated with increasing RH both at 80 and 110 °C. The fuel cell performance of this membrane, at 80 °C and 30 % RH, is better than that of the unmodified PFSA.