bluuebunny/crossref_metadata_2025 huggingface dataset:
Passivation of surface states of α-Fe2O3(0001) surface by deposition of Ga2O3 overlayers: A density functional theory study
Authors: Ulman Kanchan , Nguyen Manh-Thuong , Seriani Nicola , Gebauer Ralph
Published: March 2016

There is a big debate in the community regarding the role of surface states of hematite in the photoelectrochemical water splitting. Experimental studies on non-catalytic overlayers passivating the hematite surface states claim a favorable reduction in the overpotential for the water splitting reaction. As a first step towards understanding the effect of these overlayers, we have studied the system Ga2O3 overlayers on hematite (0001) surfaces using first principles computations in the PBE+U framework. Our computations suggest that stoichiometric terminations of Ga2O3 overlayers are energetically more favored than the bare surface, at ambient oxygen chemical potentials. Energetics suggest that the overlayers prefer to grow via a layer-plus-island (Stranski–Krastanov) growth mode with a critical layer thickness of 1–2 layers. Thus, a complete wetting of the hematite surface by an overlayer of gallium oxide is thermodynamically favored. We establish that the effect of deposition of the Ga2O3 overlayers on the bare hematite surface is to passivate the surface states for the stoichiometric termination. For the oxygen terminated surface which is the most stable termination under photoelectrochemical conditions, the effect of deposition of the Ga2O3 overlayer is to passivate the hole-trapping surface state.
Mn2+ doped ZnS quantum dots in ferroelectric liquid crystal matrix: Analysis of new relaxation phenomenon, faster optical response, and concentration dependent quenching in photoluminescence
Authors: Singh D. P. , Daoudi A. , Gupta S. K. , Pandey S. , Vimal T. , Manohar R. , Kole A. K. , Kumbhakar P. , Kumar A.
Published: March 2016

Phase transitional, dielectric, electro-optical, polarizing optical microscopic, photoluminescence (PL), and Fourier transformed infrared (FTIR) spectroscopic measurements have been carried out on ZnS:Mn quantum dots (QDs) dispersed ferroelectric liquid crystal (FLC). A new dielectric relaxation mode has been envisaged in FLC material due to the presence of 0.25 wt. % ZnS:Mn (40 mol. %) QDs. The characteristics of the new mode have been compared with those of the soft mode. A significant fastening of the electro-optical response (∼75%) has been observed in the case of 0.25 wt. % ZnS:Mn (20 mol. %) QDs doped FLC material. The induction of the new relaxation mode is attributed to the flexoelectric tilt fluctuations. The induced flexoelectric polarization in the FLC medium at the vicinity of QDs might be responsible for the enhanced spontaneous polarization in the FLC/QDs mixtures. Quenching in PL for the FLC/QDs mixtures has been observed, which strongly depends on Mn content in QDs. The change in FTIR spectra for the FLC/QDs composite clearly indicates the change in molecular dynamics of the pure FLC after the dispersion of QDs. The presented results will certainly pave a way to utilize QDs for obtaining faster response of the FLC material and potential material to tune the relaxation processes.
Giant enhancement of magnetocaloric effect at room temperature by the formation of nanoparticle of La0.48Ca0.52MnO3 compound
Authors: Das Kalipada , Das I.
Published: March 2016

Magnetocaloric effect (MCE) is the change in temperature or entropy of a material due to the application of external magnetic field. The temperature dependence of MCE shows maximum value near the ferromagnetic transition of the material. Material with large MCE near room temperature will make revolutionary change in cooling technology and will have large impact in human society. We have transformed antiferromagnetic bulk manganite material La0.48Ca0.52MnO3 to ferromagnetic material by the reduction of the particle size in nanometer scale. MCE, as well as the Relative cooling power (RCP) of the material at room temperature (RT) systematically increase with the reduction of the particle sizes. The RCP value for the 45 nm particle size sample at RT is about 400% larger compared with the bulk counterpart. Our detail study on the nano form of the compound highlights an effective way to enhance the MCE. It opens up a vast possibility of achieving giant enhancement of MCE of several already known materials just by the reduction of the particle size in nanometer scale.
Theoretical and experimental study of metastable solid solutions and phase stability within the immiscible Ag-Mo binary system
Authors: Sarakinos K. , Greczynski G. , Elofsson V. , Magnfält D. , Högberg H. , Alling B.
Published: March 2016

Metastable solid solutions are phases that are synthesized far from thermodynamic equilibrium and offer a versatile route to design materials with tailor-made functionalities. One of the most investigated classes of metastable solid solutions with widespread technological implications is vapor deposited ternary transition metal ceramic thin films (i.e., nitrides, carbides, and borides). The vapor-based synthesis of these ceramic phases involves complex and difficult to control chemical interactions of the vapor species with the growing film surface, which often makes the fundamental understanding of the composition-properties relations a challenging task. Hence, in the present study, we investigate the phase stability within an immiscible binary thin film system that offers a simpler synthesis chemistry, i.e., the Ag-Mo system. We employ magnetron co-sputtering to grow Ag1−xMox thin films over the entire composition range along with x-ray probes to investigate the films structure and bonding properties. Concurrently, we use density functional theory calculations to predict phase stability and determine the effect of chemical composition on the lattice volume and the electronic properties of Ag-Mo solid solutions. Our combined theoretical and experimental data show that Mo-rich films (x ≥ ∼0.54) form bcc Mo-Ag metastable solid solutions. Furthermore, for Ag-rich compositions (x ≤ ∼0.21), our data can be interpreted as Mo not being dissolved in the Ag fcc lattice. All in all, our data show an asymmetry with regards to the mutual solubility of Ag and Mo in the two crystal structures, i.e., Ag has a larger propensity for dissolving in the bcc-Mo lattice as compared to Mo in the fcc-Ag lattice. We explain these findings in light of isostructural short-range clustering that induces energy difference between the two (fcc and bcc) metastable phases. We also suggest that the phase stability can be explained by the larger atomic mobility of Ag atoms as compared to that of Mo. The mechanisms suggested herein may be of relevance for explaining phase stability data in a number of metastable alloys, such as ternary transition metal-aluminum-nitride systems.
Voltage induced reversible and irreversible change of magnetic coercivity in Co/ZnO heterostructure
Authors: Hsu Chuan-Che , Chang Po-Chun , Mudinepalli Venkata Ramana , Hsieh Tsung-Chun , Lo Fang-Yuh , Lin Wen-Chin
Published: March 2016

In this study, the application of bias voltage to 4–8 nm Co/275 nm ZnO heterostructures changed the magnetic behavior reversibly or irreversibly, depending on the different voltage-induced mechanisms. The magnetic coercivity (Hc) monotonically decreased 20% when the small voltages of 0–8 V were applied. The Hc reduction was symmetric with the voltage polarity, and the reversibility was demonstrated by cyclically switching the bias voltage between 0 and 7 V. While a large voltage up to 40 V was applied to the Co/ZnO junction, the current heating effect became considerable and the Co-oxide was formed, as confirmed by depth-profiling X-ray photoemission spectroscopy analysis. The presence of Co-oxide in the Co films induced the irreversible reduction of the Kerr signal and Hc at room temperature. The considerable Hc enhancement at 130 K also indicates the exchange bias coupling effect from the antiferromagnetic Co-oxide.
On the accuracy of surface hopping dynamics in condensed phase non-adiabatic problems
Authors: Chen Hsing-Ta , Reichman David R.
Published: March 2016

We perform extensive benchmark comparisons of surface hopping dynamics with numerically exact calculations for the spin-boson model over a wide range of energetic and coupling parameters as well as temperature. We find that deviations from golden-rule scaling in the Marcus regime are generally small and depend sensitively on the energetic bias between electronic states. Fewest switches surface hopping (FSSH) is found to be surprisingly accurate over a large swath of parameter space. The inclusion of decoherence corrections via the augmented FSSH algorithm improves the accuracy of dynamical behavior compared to exact simulations, but the effects are generally not dramatic, at least for the case of an environment modeled with the commonly used Debye spectral density.
P-doping and efficient carrier injection induced by graphene oxide for high performing WSe2 rectification devices
Authors: Khan Muhammad Atif , Rathi Servin , Lee Inyeal , Li Lijun , Lim Dongsuk , Kang Moonshik , Kim Gil-Ho
Published: March 2016

In this work, we fabricated multi-layer WSe2 rectifying diodes using graphene oxide (GO) as p-doping material on one side of the contacting electrodes. This GO layer can reduce the contact resistance by forming a tunneling barrier for efficient hole injection, while it increases the contact resistance for the injection of electrons. Results of Raman shift spectra and the opto-electric response of the device confirmed the p-doping effect caused by the GO layer and the formation of a barrier, respectively. We observed a gate tunable rectification effect with a forward/reverse current ratio of 104 and low reverse bias current of 10−10 A. Applying a GO layer in the fabrication of two-dimensional transition metal dichalcogenides based devices is a very useful method in the applications in future nanotechnologies.
A confocal optical microscope for detection of single impurities in a bulk crystal at cryogenic temperatures
Authors: Karlsson Jenny , Rippe Lars , Kröll Stefan
Published: March 2016

A compact sample-scanning confocal optical microscope for detection of single impurities below the surface of a bulk crystal at cryogenic temperatures is described. The sample, lens, and scanners are mounted inside a helium bath cryostat and have a footprint of only 19 × 19 mm. Wide field imaging and confocal imaging using a Blu-ray lens immersed in liquid helium are demonstrated with excitation at 370 nm. A spatial resolution of 300 nm and a detection efficiency of 1.6% were achieved.
A high-resolution time-of-flight energy analyzer for femtosecond electron pulses at 30 keV
Authors: Gliserin Alexander , Walbran Matthew , Baum Peter
Published: March 2016

We report a time-of-flight spectrometer for electron pulses at up to 30 keV, which is a suitable energy for atomic-resolution femtosecond investigations via time-resolved electron diffraction, microscopy, and energy loss spectroscopy. For realistic femtosecond beams without apertures, the instrument’s energy resolution is ∼0.5 eV (full width at half maximum) or 2 × 10−5 at a throughput of 50%-90%. We demonstrate the analyzer’s versatility by three first applications, namely, femtosecond electron pulse metrology via optical streaking, in situ drift correction in laser-microwave synchronization for electron pulse compression, and time-resolved electron energy loss spectroscopy of aluminum, showing the instrument’s capability of tracking plasmonic loss peak positions with few-meV accuracy.
Thermal generation of spin current in a multiferroic helimagnet
Authors: Takagi R. , Tokunaga Y. , Ideue T. , Taguchi Y. , Tokura Y. , Seki S.
Published: March 2016

We report the experimental observation of longitudinal spin Seebeck effect in a multiferroic helimagnet Ba0.5Sr1.5Zn2Fe12O22. Temperature gradient applied normal to Ba0.5Sr1.5Zn2Fe12O22/Pt interface generates inverse spin Hall voltage of spin current origin in Pt, whose magnitude was found to be proportional to bulk magnetization of Ba0.5Sr1.5Zn2Fe12O22 even through the successive magnetic transitions among various helimagnetic and ferrimagnetic phases. This finding demonstrates that the helimagnetic spin wave can be an effective carrier of spin current. By controlling the population ratio of spin-helicity domains characterized by clockwise/counter-clockwise manner of spin rotation with use of poling electric field in the ferroelectric helimagnetic phase, we found that spin-helicity domain distribution does not affect the magnitude of spin current injected into Pt. The results suggest that the spin-wave spin current is rather robust against the spin-helicity domain wall, unlike the case with the conventional ferromagnetic domain wall.
The adjustable anisotropy field in FeCoTiO/SiO2/FeCoTiO trilayer films by oblique sputtering and stripe patterning
Authors: Wang Yicheng , Zhang Huaiwu , Wang Luo , Bai Feiming
Published: March 2016

A series of FeCoTiO thin films were deposited on Si (100) substrates using oblique sputtering and stripe patterning at the same time and the static and high frequency magnetic properties were studied in details. For the single-layered films, if the anisotropy fields induced by the two methods are in the same direction, the effective anisotropy field will be greatly enhanced, closed to 300 Oe. But if the two anisotropy fields are perpendicular to each other, there will be an opposite result. In the FM/NM/FM sandwich structures, the influence of shape anisotropy will be suppressed by the exchange coupling effect between the two FM layers. The resonance frequency and permeability are still above 3.5 GHz and 75 even the width of stripes change from 40 µm to 10 µm.
X-ray diffraction analysis of the magnetoelastic phase transition in the Mn-Fe-P-Si magnetocaloric alloy
Authors: Pasko Alexandre , Bartok Andras , Zehani Karim , Bessais Lotfi , Mazaleyrat Frederic , LoBue Martino
Published: March 2016

Structural characterization of the Mn1.3Fe0.65P0.5Si0.5 powder is reported. The rare-earth-free magnetocaloric material was prepared by ball milling and solid-state synthesis. X-ray diffraction data were collected in a wide temperature range across the magnetoelastic phase transition. The lattice parameters and volume fractions of the paramagnetic and ferromagnetic phases were determined as functions of temperature using Rietveld fitting. The virgin effect (a delay of the phase transition on first cooling) and associated variation of lattice parameters are analyzed on the assumption of elastic constraints imposed on the paramagnetic phase by the defect structure. A simple Landau model with magnetoelastic coupling illustrates the observed first-order behavior.
Core/shell-structured nickel/nitrogen-doped onion-like carbon nanocapsules with improved electromagnetic wave absorption properties
Authors: Wu Niandu , Liu Xianguo , Or Siu Wing
Published: March 2016

Core/shell-structured nickel/nitrogen-doped onion-like carbon (Ni/(C, N)) nanocapsules are synthesized by a modified arc-discharge method using N2 gas as the source of N atoms. Core/shell-structured Ni/C nanocapsules are also prepared for comparison. The Ni/(C, N) nanocapsules with diameters of 10–80 nm exhibit a clear core/shell structure. The doping of N atoms introduces more lattice defects into the (C, N) shells and creates more disorderly C in the (C, N) shells. This leads to a slight shift in the dielectric resonance peak to the lower frequency side and an increase in the dielectric loss tangent for the Ni/(C, N) nanocapsules in comparison with the Ni/C nanocapsules. The magnetic permeability of both types of nanocapsules remains almost unaltered since the N atoms exist only in the (C, N) shells. The reflection loss (RL) of the Ni/(C, N) nanocapsules not only reaches a high value of -35 dB at 13.6 GHz, but also is generally improved in the low-frequency S and C microwave bands covering 2–8 GHz as a result of the N-doping-induced additional dipolar polarization and dielectric loss from the (C, N) shells.
What went wrong with the Los Alamos contract?
Authors: Kramer David
Published: March 2016

Before the $2.2 billion annual contract to run the lab ends in 2017, DOE must decide whether a new management model is needed.
Safeguarding nuclear material may be losing urgency
Authors: Kramer David
Published: March 2016

Since 2014 just one nation has rid itself of all weapons-usable materials.
Ultrasound-mediated drug delivery
Authors: Goertz David , Hynynen Kullervo
Published: March 2016

Thanks to advances in transducer technology and imaging-based guidance systems and the expanding body of research on the therapeutic benefits, ultrasound techniques are poised to improve the treatment of cancer and other diseases in the clinic.
The retrovirus HTLV-1 inserts an ectopic CTCF-binding site into the human genome
Authors: Satou Yorifumi , Miyazato Paola , Ishihara Ko , Yaguchi Hiroko , Melamed Anat , Miura Michi , Fukuda Asami , Nosaka Kisato , Watanabe Takehisa , Rowan Aileen G. , Nakao Mitsuyoshi , Bangham Charles R. M.
Published: March 2016

Significance

The retrovirus human T-lymphotropic virus type 1 (HTLV-1) causes inflammatory and malignant diseases in humans. To maintain latency and avoid immune detection in vivo, HTLV-1 minimizes expression of genes on the plus-strand of the integrated provirus but allows constitutive expression of the minus-strand gene, which maintains clonal persistence. It is not understood how this gene expression is regulated. We show that CTCF, a master regulator of chromatin structure and gene expression, binds to HTLV-1, forms loops between the provirus and host genome, and alters expression of proviral and host genes. Because a typical HTLV-1–infected host carries >10
4
infected T-cell clones, each containing a provirus integrated in a different genomic site, CTCF binding gives HTLV-1 the potential to cause widespread abnormalities in the human genome.
Ablation of sensory neurons in a genetic model of pancreatic ductal adenocarcinoma slows initiation and progression of cancer
Authors: Saloman Jami L. , Albers Kathryn M. , Li Dongjun , Hartman Douglas J. , Crawford Howard C. , Muha Emily A. , Rhim Andrew D. , Davis Brian M.
Published: March 2016

Significance

In humans and genetically engineered mouse models (GEMs), the development of pancreatic ductal adenocarcinoma (PDAC) is accompanied by intimate neural–tumor interactions. Using a PDAC GEM that phenocopies the human disease, we found that many changes in peripheral and central nervous systems, indicative of injury and inflammation, arise at time points prior to overt tumor formation. Ablation of sensory neurons that innervate the pancreas, via neonatal capsaicin treatment, prevented neurogenic inflammation and delayed tumor formation. The slowing of PDAC in capsaicin-treated mice suggests the nervous system is not a bystander with respect to disease progression. Further studies are warranted to examine nervous system–tumor interactions and to identify potential targets for early detection, prevention, and treatment.
Actomyosin dynamics drive local membrane component organization in an in vitro active composite layer
Authors: Köster Darius Vasco , Husain Kabir , Iljazi Elda , Bhat Abrar , Bieling Peter , Mullins R. Dyche , Rao Madan , Mayor Satyajit
Published: March 2016

Significance

This manuscript addresses the role of active processes in the spatial organization and dynamics of cell surface components. Using a reconstituted minimal system, we provide experimental evidence for a proposed clustering mechanism that relies on the intrinsic, active mechanics of actin filaments and myosin motors expected to be present at the cell cortex. The coupling between the actomyosin and the lipid bilayer gives rise to an emergent active composite with properties that resemble those observed in live cells. This clustering mechanism is a key feature of the active composite cell surface model and furthers our understanding of the multiple ways in which the cell surface might regulate its composition.
Autoinhibition and relief mechanism by the proteolytic processing of Toll-like receptor 8
Authors: Tanji Hiromi , Ohto Umeharu , Motoi Yuji , Shibata Takuma , Miyake Kensuke , Shimizu Toshiyuki
Published: March 2016

Significance

Toll-like receptors (TLRs) activate the innate immune system in response to invading pathogens. The single-stranded RNA (ssRNA) sensor TLR8 requires proteolytic cleavage at the loop region (Z-loop) for its activation. Biochemical and biophysical studies have revealed that the uncleaved Z-loop prevents formation of the TLR8 dimer, which is essential for its activation. Crystallographic analysis demonstrated that the uncleaved Z-loop located on the ascending lateral face prevents the approach of the dimerization partner by steric hindrance. Like TLR8, TLR7 and TLR9 also contain the Z-loop, and thus these proteins also might have this autoinhibition mechanism.
Mechanisms of backtrack recovery by RNA polymerases I and II
Authors: Lisica Ana , Engel Christoph , Jahnel Marcus , Roldán Édgar , Galburt Eric A. , Cramer Patrick , Grill Stephan W.
Published: March 2016

Significance

Transcription of the genetic information from DNA into RNA is the central process of gene expression, and it is performed by enzymes called RNA polymerases (Pol). Transcription is interspersed with a proofreading mechanism called backtracking, during which the polymerase moves backward on the DNA template and displaces the RNA 3′ end from its active site. Backtrack recovery can happen by diffusion of the enzyme along the DNA or cleavage of the backtracked RNA. Using single-molecule optical tweezers and stochastic theory, we quantified distinct diffusion and cleavage rates of Pol I and Pol II and described distinct backtrack recovery strategies of these essential enzymes.
Excitatory synapses are stronger in the hippocampus of Rett syndrome mice due to altered synaptic trafficking of AMPA-type glutamate receptors
Authors: Li Wei , Xu Xin , Pozzo-Miller Lucas
Published: March 2016

Significance

Rett syndrome is the most common intellectual disability in women after Down syndrome (1:10,000 incidence). Different mouse models of intellectual disability and autism exhibit deficits in synaptic plasticity, including impaired long-term potentiation (LTP) in mice lacking methyl-CpG-binding protein 2 (MeCP2); however, the bases of this deficit remain unclear. Using a combination of electrophysiology, time-lapse imaging, cell biology, and biochemistry, we provide direct evidence that naïve hippocampal synapses in Rett mice have all the hallmarks of potentiated synapses. Rett synapses also fail to insert and remove AMPA receptors properly to activated synapses, which freezes them in a nonplastic state. Our findings provide molecular, cellular, and network mechanisms underlying enhanced excitatory synaptic transmission and impaired LTP in Rett mice, identifying previously unidentified molecular targets for therapeutic intervention.
Delayed fungal evolution did not cause the Paleozoic peak in coal production
Authors: Nelsen Matthew P. , DiMichele William A. , Peters Shanan E. , Boyce C. Kevin
Published: March 2016

Significance

The Carboniferous−Permian marks the greatest coal-forming interval in Earth’s history, contributing to glaciation and uniquely high oxygen concentrations at the time and fueling the modern Industrial Revolution. This peak in coal deposition is frequently attributed to an evolutionary lag between plant synthesis of the recalcitrant biopolymer lignin and fungal capacities for lignin degradation, resulting in massive accumulation of plant debris. Here, we demonstrate that lignin was of secondary importance in many floras and that shifts in lignin abundance had no obvious impact on coal formation. Evidence for lignin degradation—including fungal—was ubiquitous, and absence of lignin decay would have profoundly disrupted the carbon cycle. Instead, coal accumulation patterns implicate a unique combination of climate and tectonics during Pangea formation.
Dynamics inside the cancer cell attractor reveal cell heterogeneity, limits of stability, and escape
Authors: Li Qin , Wennborg Anders , Aurell Erik , Dekel Erez , Zou Jie-Zhi , Xu Yuting , Huang Sui , Ernberg Ingemar
Published: March 2016

Significance

It has been proposed, based on theory of complex gene regulatory networks, that cell types, including cancer cells, represent attractor states of the network dynamics. Here, we characterize for the first time, to our knowledge, the detailed dynamics of a cancer cell attractor at single-cell resolution. The results provide quantitative knowledge on nongenetic intercellular heterogeneity and its dynamics within an isogenic cell population of cancerous cells, affording insights at a previously unidentified level of resolution between molecular pathways and macroscopic tumor behaviors. This new dimension of characterizing tumor cells might impact design of future rational cancer therapies by taking into account the dynamic robustness and high volatility of a heterogeneous cancer cell population.
Regulation of seminiferous tubule-associated stem Leydig cells in adult rat testes
Authors: Li Xiaoheng , Wang Zhao , Jiang Zhenming , Guo Jingjing , Zhang Yuxi , Li Chenhao , Chung Jinyong , Folmer Janet , Liu June , Lian Qingquan , Ge Renshan , Zirkin Barry R. , Chen Haolin
Published: March 2016

Significance

Leydig cells, derived from stem cells, are the primary source of testosterone in males. Testosterone deficiency has been linked to sexual dysfunction and decreased bone density, muscle mass, and cognition. Thus, the formation and maintenance of the Leydig cell population is of fundamental importance. Through the use of a unique tubule culture system, we have identified critical niche factors that control the proliferation and differentiation of the Leydig stem cells. Additionally, we report on the isolation and purification of these cells through a specific cell surface marker protein.
Disrupted iron homeostasis causes dopaminergic neurodegeneration in mice
Authors: Matak Pavle , Matak Andrija , Moustafa Sarah , Aryal Dipendra K. , Benner Eric J. , Wetsel William , Andrews Nancy C.
Published: March 2016

Significance

The brain requires iron for mitochondrial respiration and synthesis of myelin, neurotransmitters, and monoamine oxidases. Iron accumulates in distinct parts of the brain in patients with neurodegenerative diseases, and some have proposed that neurons die because they contain too much iron. Neuronal iron handling is not well understood. We focused on dopaminergic neurons, affected in Parkinson’s disease, and manipulated molecules involve in iron uptake and release. We showed that loss of ferroportin, which exports cellular iron, had no apparent effect. In contrast, loss of transferrin receptor, involved in iron uptake, caused neuronal iron deficiency and neurodegeneration with features similar to Parkinson’s disease. We propose that neuronal iron deficiency may contribute to neurodegeneration in human disease.
Importin-7 mediates memory consolidation through regulation of nuclear translocation of training-activated MAPK in
Drosophila
Authors: Li Qian , Zhang Xuchen , Hu Wantong , Liang Xitong , Zhang Fang , Wang Lianzhang , Liu Zhong-Jian , Zhong Yi
Published: March 2016

Significance

Nuclear import of training-activated signaling molecules is an essential step in initiating memory consolidation. As importin-dependent nuclear translocation is reported in regulation of long-term synaptic plasticity, the current work identified the
Drosophila
homolog of vertebrate importin-7 (DIM-7), in determining consolidation of the protein synthesis-dependent long-term memory (LTM). The amount of DIM-7 expressed determines the level of LTM consolidated and the level of accumulation of behavioral-activated MAPK within the nuclei of mushroom body neurons. Thus, only training that produces LTM could activate DIM-7–dependent pMAPK translocation for initiating memory consolidation.
Material heterogeneity in cancellous bone promotes deformation recovery after mechanical failure
Authors: Torres Ashley M. , Matheny Jonathan B. , Keaveny Tony M. , Taylor David , Rimnac Clare M. , Hernandez Christopher J.
Published: March 2016

Significance

Lightweight structures often use foam cores to achieve high strength and stiffness. Structures that are submitted to cyclic loading with long service lives must also resist crack propagation. We show that the foam-like regions of cancellous bone resist damage propagation by varying material heterogeneity within struts, a strategy that makes the material less susceptible to stress concentrations at the surface and enhances the ability of the structure to recover its initial shape after mechanical failure. The ability to recover deformation after failure improves long-term function of bones after a fracture. Our findings suggest a previously unidentified design strategy of man-made foams in which material heterogeneity can be used to mitigate the effect of local failure to better maintain mechanical function.
Early signaling dynamics of the epidermal growth factor receptor
Authors: Reddy Raven J. , Gajadhar Aaron S. , Swenson Eric J. , Rothenberg Daniel A. , Curran Timothy G. , White Forest M.
Published: March 2016

Significance

To date, poor temporal resolution of response measurement has obscured the complex initiation of receptor tyrosine kinase (RTK) signaling that governs cellular response to stimulation. To address this deficiency, we have performed a systems-level characterization of the phosphorylation changes that occur in the immediate period after growth factor stimulation with 10-s resolution. We treated MCF-10A cells with EGF and measured tyrosine phosphorylation levels from 0 to 80 s on hundreds of sites in the cell. Examining phosphorylation dynamics on this timescale reveals patterns that were not observable with slower sampling rates. We further explore the roles of negative and positive feedback, providing further insight into systems-level behaviors of the EGF receptor (EGFR) signaling network.
Immunoproteasome deficiency is a feature of non-small cell lung cancer with a mesenchymal phenotype and is associated with a poor outcome
Authors: Tripathi Satyendra C. , Peters Haley L. , Taguchi Ayumu , Katayama Hiroyuki , Wang Hong , Momin Amin , Jolly Mohit Kumar , Celiktas Muge , Rodriguez-Canales Jaime , Liu Hui , Behrens Carmen , Wistuba Ignacio I. , Ben-Jacob Eshel , Levine Herbert , Molldrem Jeffrey J. , Hanash Samir M. , Ostrin Edwin J.
Published: March 2016

Significance

The success rate of therapeutic trials that target tumor antigens is quite limited. We demonstrate for the first time to our knowledge that lung cancer cells that have undergone epithelial-to-mesenchymal transition lose immunoproteasome expression, resulting in markedly reduced antigen presentation. Reduced expression of the immunoproteasome was associated with and can predict poor outcome in non-small cell lung carcinoma (NSCLC) patients. Induction of the immunoproteasome with IFNγ or 5-aza-2′-deoxycytidine (5-aza-dC) treatment can overcome this immune escape mechanism of mesenchymal cells by restoring functional HLA class I-bound peptides. These findings have substantial relevance for development of effective strategies to target tumor cells with inherent resistance to T cell-mediated immunotherapy.
Continued emissions of carbon tetrachloride from the United States nearly two decades after its phaseout for dispersive uses
Authors: Hu Lei , Montzka Stephen A. , Miller Ben R. , Andrews Arlyn E. , Miller John B. , Lehman Scott J. , Sweeney Colm , Miller Scot M. , Thoning Kirk , Siso Carolina , Atlas Elliot L. , Blake Donald R. , de Gouw Joost , Gilman Jessica B. , Dutton Geoff , Elkins James W. , Hall Bradley , Chen Huilin , Fischer Marc L. , Mountain Marikate E. , Nehrkorn Thomas , Biraud Sebastien C. , Moore Fred L. , Tans Pieter
Published: March 2016

Significance

Global-scale observations suggest large unexplained emissions of the ozone-depleting chemical carbon tetrachloride (CCl
4
) despite stringent limits on its production for dispersive uses for many years. Identifying the sources of continued CCl
4
emission is necessary before steps can be taken to accelerate the emission decline and limit future ozone depletion. Results from an extensive air sampling network over the United States indicate continued emission of CCl
4
with a similar distribution but much larger magnitude than industrial facilities reporting emissions to the US Environmental Protection Agency. If these emissions are attributable to chlorine production and processing and are indicative of release rates of CCl
4
from these industries worldwide, a large fraction of ongoing global emissions of CCl
4
can be explained.
Human DNMT1 transition state structure
Authors: Du Quan , Wang Zhen , Schramm Vern L.
Published: March 2016

Significance

DNA methyltransferase 1 (DNMT1) is the major enzyme responsible for maintenance of DNA CpG methylation marks in human cells. The enzyme is a validated target for cancer, but current treatments are mutagenic. Knowledge of the transition state (TS) structure of DNMT1 will inform the chemical reaction mechanism and provide information for TS analog design. Here, we report the subangstrom geometric and electrostatic character of the TS for the DNMT1 methylation of hemimethylated DNA. The experimental and computational TS analysis indicates methyl transfer is the rate-limiting chemical step for the reaction. Methyl group transfer can be characterized as a loose nucleophilic substitution TS. TS analysis of DNMT1 demonstrates an approach to understand a complex epigenetic enzyme.
Pten loss promotes MAPK pathway dependency in HER2/neu breast carcinomas
Authors: Ebbesen Saya H. , Scaltriti Maurizio , Bialucha Carl U. , Morse Natasha , Kastenhuber Edward R. , Wen Hannah Y. , Dow Lukas E. , Baselga José , Lowe Scott W.
Published: March 2016

Significance

PTEN
mutations are associated with disease progression and therapy resistance in human epidermal growth factor receptor 2 (
HER2/neu
)-amplified breast cancer patients but the role of PTEN loss in breast cancer maintenance is unknown. Here, using a regulatable RNAi mouse model of HER2/neu-driven metastatic breast cancer, we show that
Pten
silencing accelerates disease progression and that restoration of endogenous
Pten
expression triggers marked disease regression. By comparing and contrasting how pharmacologic perturbations of various signaling pathways compare to genetic reactivation of Pten, we identify a requirement for Mek signaling in Pten-suppressed tumors. Our findings imply that even advanced tumors can remain dependent on Pten loss and provide a rationale for exploring the utility of MEK inhibitors in therapy-resistant breast cancer patients acquiring
PTEN
mutations.
Inactivation of 3-
hydroxybutyrate dehydrogenase
2 delays zebrafish erythroid maturation by conferring premature mitophagy
Authors: Davuluri Gangarao , Song Ping , Liu Zhuoming , Wald David , Sakaguchi Takuya F. , Green Michael R. , Devireddy L.
Published: March 2016

Significance

In addition to their well-documented roles in energy metabolism and heme biogenesis, mitochondria also play an important role in intracellular signaling, which is important for tissue and organ development. We previously showed that a cytosolic siderophore facilitates mitochondrial iron import in eukaryotes. Depletion of the siderophore by inactivating 3-hydroxy butyrate dehydrogenase 2 (
bdh
2), whose gene product is necessary for siderophore biogenesis, results in heme deficiency and delays erythroid maturation in developing zebrafish embryo. Here we show that inactivation of
bdh
2 results in mitochondrial dysfunction, triggers their degradation by mitophagy, and hampers erythroid maturation. Reestablishment of
bdh
2 restores mitochondrial function, prevents premature mitochondrial degradation, and promotes erythroid maturation. Our results demonstrate that mitochondrial communication with the nucleus is critical for erythroid development.
Novel actin filaments from
Bacillus thuringiensis
form nanotubules for plasmid DNA segregation
Authors: Jiang Shimin , Narita Akihiro , Popp David , Ghoshdastider Umesh , Lee Lin Jie , Srinivasan Ramanujam , Balasubramanian Mohan K. , Oda Toshiro , Koh Fujiet , Larsson Mårten , Robinson Robert C.
Published: March 2016

Significance

Actins and tubulins have dedicated functions that vary between eukaryotes and prokaryotes. During cell division, the prokaryotic contractile ring depends on the tubulin-like protein FtsZ, whereas this task relies on actin in eukaryotes. In contrast, microtubules orchestrate DNA segregation in eukaryotes, yet prokaryotic plasmid segregation often depends on actin-like proteins; this implies that actins and tubulins have somewhat interchangeable properties. Hence, we sought a bacterial filament that more closely resembles microtubules. Here, we report an actin from
Bacillus thuringiensis
that forms dynamic, antiparallel, two-stranded supercoiled filaments, which pair in the presence of a binding partner to form hollow cylinders. Thus, in this prokaryote, the actin fold has evolved to produce a filament system with comparable properties to the eukaryotic microtubule.
Acetylcholine receptors from human muscle as pharmacological targets for ALS therapy
Authors: Palma Eleonora , Reyes-Ruiz Jorge Mauricio , Lopergolo Diego , Roseti Cristina , Bertollini Cristina , Ruffolo Gabriele , Cifelli Pierangelo , Onesti Emanuela , Limatola Cristina , Miledi Ricardo , Inghilleri Maurizio
Published: March 2016

Significance

Amyotrophic lateral sclerosis (ALS) is a fatal disease leading to motor neuron degeneration and progressive paralysis. Other studies have revealed defects in skeletal muscle even in the absence of motor neuron anomalies, focusing on acetylcholine receptors (AChRs) and supporting the so-called “dying-back” hypothesis. Our results indicate that the endocannabinoid palmitoylethanolamide (PEA) reduces the rundown of AChRs currents in ALS muscle and can clinically improve patients’ pulmonary function. This study strengthens the important role of muscle in ALS pathogenesis and the idea that AChRs can be therapeutic targets.
Impacts of nonstate, market-driven governance on Chilean forests
Authors: Heilmayr Robert , Lambin Eric F.
Published: March 2016

Significance

Global trade in commodities has become an important driver of environmental degradation. In response, there has been a proliferation of nonstate, market-driven governance seeking to reduce environmental degradation through interventions in the supply chain. We provide some of the first quasiexperimental evidence to show that private, market-driven policies can slow deforestation. We compare the impacts of two certification schemes and a deforestation moratorium in Chile using a factorial quasiexperimental design. Our results indicate that governance regimes with greater collaboration between environmental and industry stakeholders achieved better environmental outcomes. In contrast to many public conservation policies, we find that private governance systems can effectively target high-deforestation properties.
Spectral gap optimization of order parameters for sampling complex molecular systems
Authors: Tiwary Pratyush , Berne B. J.
Published: March 2016

Significance

Molecular-dynamics (MD) simulations have become a versatile tool for exploration of complex molecular systems. However, they are limited in the timescales that can be reached. Thus, over the years, a suite of enhanced-sampling algorithms have been proposed that assist MD to transcend the timescale limitation, with diverse applications across physical and life sciences. A continuing grand challenge in the success of many such sampling methods pertains to a judicious choice of order parameters. In this work, we propose a new method for designing order parameters that minimizes the role played by human intuition and makes the progress significantly more automated than before. We expect this algorithm to be of great use in furthering the success of enhanced sampling.
Paracrine Wnt/β-catenin signaling mediates proliferation of undifferentiated spermatogonia in the adult mouse testis
Authors: Takase Hinako M. , Nusse Roeland
Published: March 2016

Significance

Spermatogonial stem cells are unique among adult tissue stem cells in their role in transmitting genetic information to the next generation. Germ-line stem cells in
Caenorhabditis elegans
and
Drosophila
are well studied because of their relatively simple organization with a clear anatomical niche, but the regulatory mechanisms behind mammalian spermatogonial stem cells are less well understood. In this report, we demonstrate that the proliferation of undifferentiated spermatogonia, including spermatogonial stem cells, is controlled by Wnt/β-catenin signaling. Wnts are secreted by Sertoli cells, which thereby act as a niche. To our knowledge, this work proves, for the first time, that Wnt/β-catenin signaling is involved in spermatogonial stem/progenitor cell regulation in vivo, and also uncovers its mode of action.
Two distinct cytokinesis pathways drive trypanosome cell division initiation from opposite cell ends
Authors: Zhou Qing , Gu Jianhua , Lun Zhao-Rong , Ayala Francisco J. , Li Ziyin
Published: March 2016

Significance

Cytokinesis occurs along a cell’s short axis in many organisms, including bacteria, archaea, and eukaryotes. In many protozoa it occurs along the cell’s longitudinal axis. The mechanism underlying this mode of cytokinesis is unknown. We delineate the signaling cascade that regulates cytokinesis along the longitudinal axis of
Trypanosoma brucei
, which is totally different from that in its human host. Additionally, we discover an alternative cytokinesis pathway that drives trypanosome cell division along the same division plane as the typical cytokinesis, but in an opposite direction. This alternative cytokinesis is activated only when the typical cytokinesis pathway is defective, suggesting that trypanosomes have evolved a backup cytokinesis mechanism to prevent the failure of cell division, thereby ensuring survival of this organism.
The Muslim uprising in Ajara and the Stalinist revolution in the periphery
Authors: Blauvelt Timothy K. , Khatiashvili Giorgi
Published: March 2016

In 1929, local officials in the mountainous region of upper Ajara in the Georgian Soviet Socialist Republic (SSR) pursued aggressive policies to force women to remove their veils and to close religious schools, provoking the Muslim peasant population to rebellion in one of the largest and most violent of such incidents in Soviet history. The central authorities in Moscow authorized the use of Red Army troops to suppress the uprising, but they also reversed the local initiatives and offered the peasants concessions. Based on Party and secret police files from the Georgian archives in Tbilisi and Batumi, this article will explore the ways in which local cadres interpreted regime policies in this Muslim region of Georgia, and the interaction of the center and periphery in dealing with national identity, Islam, gender, and everyday life in the early Soviet period.
Redox regulation of ascorbate and glutathione by a chloroplastic dehydroascorbate reductase is required for high-light stress tolerance in Arabidopsis
Authors: Noshi Masahiro , Hatanaka Risa , Tanabe Noriaki , Terai Yusuke , Maruta Takanori , Shigeoka Shigeru
Published: March 2016

Chloroplasts are a significant site for reactive oxygen species production under illumination and, thus, possess a well-organized antioxidant system involving ascorbate. Ascorbate recycling occurs in different manners in this system, including a dehydroascorbate reductase (DHAR) reaction. We herein investigated the physiological significance of DHAR3 in photo-oxidative stress tolerance in Arabidopsis. GFP-fused DHAR3 protein was targeted to chloroplasts in Arabidopsis leaves. A DHAR3 knockout mutant exhibited sensitivity to high light (HL). Under HL, the ascorbate redox states were similar in mutant and wild-type plants, while total ascorbate content was significantly lower in the mutant, suggesting that DHAR3 contributes, at least to some extent, to ascorbate recycling. Activation of monodehydroascorbate reductase occurred in dhar3 mutant, which might compensate for the lack of DHAR3. Interestingly, glutathione oxidation was consistently inhibited in dhar3 mutant. These findings indicate that DHAR3 regulates both ascorbate and glutathione redox states to acclimate to HL.
“How Do You Want to be Wise?”: The Influence of the Progymnasmata on Ælfrīc’s Colloquy
Authors: Loveridge Jordan
Published: March 2016

This essay analyzes the tenth-century pedagogical text Ælfrīc’s Colloquy as an instance of Anglo-Saxon rhetorical instruction in the spirit of the Greco-Roman progymnasmata. Through a comparison of the text with classical sources such as Priscian’s adaptations of Hermogenes and Isidore’s Etymologies, this essay concludes that Ælfrīc knew of the progymnasmata and that these exercises served as the basis for rhetorical instruction that emphasized Benedictine ideals of communal concord through trained speaking and writing. Drawing on the commonplace of the three estates, the Colloquy demonstrated the ideal role of rhetoric in Anglo-Saxon society while modeling traditional progymnasmata exercises such as fable composition, impersonations, and comparisons.
A (Hetero)Topology of Rhetoric and Obama’s African Dreams
Authors: Chirindo Kundai
Published: March 2016

The emplacements of rhetoric are manifold and the inquiries into the topologies of rhetoric are ways of understanding developments in rhetorical theory. To these ends, I contrast in this article the invocations of place in rhetorical theory old and new. In this long view, the spatiality of rhetoric appears to be multifaceted. I show that in Greco-Roman rhetorical theory, spatiality is topical, figured metaphorically and literally, and functions as a precedent condition for rhetoric. I argue that modern/postmodern theories differ from traditional theories of rhetoric not because they rely more or less on the materiality or immateriality of place, but because of their orientations to place as heterotopic, that is, as fluid and contingent. I then offer an account of how heterotopic rhetoric challenges orders of knowledge allowing for ever-new articulations through a close reading of Barack Obama’s Dreams from my Father. The heterotopology of rhetoric proposed here expands understandings of the heuristic function of place. The essay considers the implications heterotopic place holds for identity and subjectivity.
The glycolytic enzyme PKM2 bridges metabolic and inflammatory dysfunction in coronary artery disease
Authors: Shirai Tsuyoshi , Nazarewicz Rafal R. , Wallis Barbara B. , Yanes Rolando E. , Watanabe Ryu , Hilhorst Marc , Tian Lu , Harrison David G. , Giacomini John C. , Assimes Themistocles L. , Goronzy Jörg J. , Weyand Cornelia M.
Published: March 2016

Abnormal glucose metabolism and enhanced oxidative stress accelerate cardiovascular disease, a chronic inflammatory condition causing high morbidity and mortality. Here, we report that in monocytes and macrophages of patients with atherosclerotic coronary artery disease (CAD), overutilization of glucose promotes excessive and prolonged production of the cytokines IL-6 and IL-1β, driving systemic and tissue inflammation. In patient-derived monocytes and macrophages, increased glucose uptake and glycolytic flux fuel the generation of mitochondrial reactive oxygen species, which in turn promote dimerization of the glycolytic enzyme pyruvate kinase M2 (PKM2) and enable its nuclear translocation. Nuclear PKM2 functions as a protein kinase that phosphorylates the transcription factor STAT3, thus boosting IL-6 and IL-1β production. Reducing glycolysis, scavenging superoxide and enforcing PKM2 tetramerization correct the proinflammatory phenotype of CAD macrophages. In essence, PKM2 serves a previously unidentified role as a molecular integrator of metabolic dysfunction, oxidative stress and tissue inflammation and represents a novel therapeutic target in cardiovascular disease.