bluuebunny/crossref_metadata_2025 huggingface dataset:
Ventral striatal dysfunction in cocaine dependence – difference mapping for subregional resting state functional connectivity
Authors: Zhang Sheng , Li Chiang-Shan R.
Published: June 2018

Research of dopaminergic deficits has focused on the ventral striatum (VS) with many studies elucidating altered resting state functional connectivity (rsFC) in individuals with cocaine dependence (CD). The VS comprises functional subregions and delineation of subregional changes in rsFC requires careful consideration of the differences between addicted and healthy populations. In the current study, we parcellated the VS using whole-brain rsFC differences between CD and non-drug-using controls (HC). Voxels with similar rsFC changes formed functional clusters. The results showed that the VS was divided into 3 subclusters, in the area of the dorsal-anterior VS (daVS), dorsal posterior VS (dpVS), and ventral VS (vVS), each in association with different patterns of rsFC. The three subregions shared reduced rsFC with bilateral hippocampal/parahippocampal gyri (HG/PHG) but also showed distinct changes, including reduced vVS rsFC with ventromedial prefrontal cortex (vmPFC) and increased daVS rsFC with visual cortex in CD as compared to HC. Across CD, daVS visual cortical connectivity was positively correlated with amount of prior-month cocaine use and cocaine craving, and vVS vmPFC connectivity was negatively correlated with the extent of depression and anxiety. These findings suggest a distinct pattern of altered VS subregional rsFC in cocaine dependence, and some of the changes have eluded analyses using the whole VS as a seed region. The findings may provide new insight to delineating VS circuit deficits in cocaine dependence and provide an alternative analytical framework to address functional dysconnectivity in other mental illnesses.
Statistical analysis and estimation of the regional trend of aerosol size over the Arabian Gulf Region during 2002–2016
Authors: Barbulescu Alina , Nazzal Yousef , Howari Fares
Published: June 2018

In this article, we present the results of the regional estimation of the evolution of monthly mean aerosol size over the Arabian Gulf Region, based on the data collected during the period July 2002 – September 2016. The dataset used is complete, without missing values. Two methods are introduced for this purpose. The first one is based on the partition of the regional series in sub-series and the selection of the most representative one for fitting the regional trend. The second one is a version of the first method, combined with the k-means clustering algorithm. Comparison of their performances is also provided. The study proves that both methods give a very good estimation of the evolution of the aerosol size in the Arabian Gulf Region in the study period.
Real-time ex-vivo measurement of brain metabolism using hyperpolarized [1-13C]pyruvate
Authors: Harris Talia , Azar Assad , Sapir Gal , Gamliel Ayelet , Nardi-Schreiber Atara , Sosna Jacob , Gomori J. Moshe , Katz-Brull Rachel
Published: June 2018

The ability to directly monitor in vivo brain metabolism in real time in a matter of seconds using the dissolution dynamic nuclear polarization technology holds promise to aid the understanding of brain physiology in health and disease. However, translating the hyperpolarized signal observed in the brain to cerebral metabolic rates is not straightforward, as the observed in vivo signals reflect also the influx of metabolites produced in the body, the cerebral blood volume, and the rate of transport across the blood brain barrier. We introduce a method to study rapid metabolism of hyperpolarized substrates in the viable rat brain slices preparation, an established ex vivo model of the brain. By retrospective evaluation of tissue motion and settling from analysis of the signal of the hyperpolarized [1-13C]pyruvate precursor, the T1s of the metabolites and their rates of production can be determined. The enzymatic rates determined here are in the range of those determined previously with classical biochemical assays and are in agreement with hyperpolarized metabolite relative signal intensities observed in the rodent brain in vivo.
Response of Onion (Allium cepa L.) to nitrogen fertilizer rates and spacing under rain fed condition at Tahtay Koraro, Ethiopia
Authors: Gebretsadik Kiros , Dechassa Nigussie
Published: June 2018

Onion is important in the daily Ethiopian diet though the average yield obtained by farmers is very low. This is attributed to a number of constraints among which are poor agronomic practices. Therefore, field experiment was conducted at Tahtay Koraro district to study the effect of nitrogen fertilizer and intra-row spacing on growth and yield of onion. The treatments consisted of a factorial combination of four rates of nitrogen (0, 50, 100 and 150 kg N ha−1) and four intra- row spacings (4, 6, 8, and 10 cm). Bombay Red was the variety of onion used in the experiment. The experiment was laid out as RCBD with three replications. The analysis of variance revealed that N and intra-row spacing were significant. Both N and intra-row spacing significantly affected percentage of Bolting plants, leaf length, bulb diameter, and marketable yield. 100 kg N ha−1 and a population of 833,300 plants ha−1 was found to be the optimum rate to obtain higher marketable bulb yield of 26.72 t ha−1 and economically attractive benefits. Therefore, Bombay red variety could be planted at an optimum spacing of 6 cm × 20 cm or 833,300 plant population density ha−1 in Tahtay koraro district of northern Ethiopia.
Pretreatment prediction of pathologic complete response to neoadjuvant chemotherapy in breast cancer: Perfusion metrics of dynamic contrast enhanced MRI
Authors: Lee Jeongmin , Kim Sung Hun , Kang Bong Joo
Published: June 2018

The purpose of this study was to investigate imaging parameters predicting pathologic complete response (pCR) in pretreatment dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) in breast cancer patients who were treated with neoadjuvant chemotherapy (NAC). A total of 74 patients who received NAC followed by surgery were retrospectively reviewed. All patients underwent breast MRI before NAC. Perfusion parameters including Ktrans, Kep and Ve of tumor were measured three-dimensionally. These perfusion parameters of background parenchyma of contralateral breasts were analyzed two-dimensionally. Receiver-operating characteristic (ROC) analysis and multivariable logistic regression analysis were performed to compare the ability of perfusion parameters to predict pCR. Of 74 patients, 13 achieved pCR in final pathology. The fiftieth percentile and skewness of each perfusion parameter – Ktrans, Kep, and Ve of tumor were associated with pCR. Perfusion parameters of contralateral breast parenchyma in 2D analysis also showed predictive ability for pCR. The model combining perfusion parameters of contralateral breast background parenchyma and those of the tumor had higher predictive value than each single parameter. Thus, perfusion parameters of tumor, background parenchyma of contralateral breast and their combinations in pretreatment breast MRI allow early prediction for pCR of breast cancer.
Picosecond supercontinuum generation in large mode area photonic crystal fibers for coherent anti-Stokes Raman scattering microspectroscopy
Authors: Shen Yujie , Voronin Alexander A. , Zheltikov Aleksei M. , O’Connor Sean P. , Yakovlev Vladislav V. , Sokolov Alexei V. , Scully Marlan O.
Published: June 2018

We perform a detailed theoretical and experimental investigation of supercontinuum generation in large-mode-area photonic crystal fibers pumped by a high-energy, high-repetition rate picosecond Nd:YVO4 laser, with the goal of using it as the Stokes beam in coherent anti-Stokes Raman scattering setup. We analyze the influence of fiber structure and length on the supercontinuum power, spectral shape, and group delay dispersion. We identify the experimental conditions for stable supercontinuum generation, with microjoule-level pulse energy and the spectrum extending beyond 1600 nm, which allows excitation of Raman frequencies up to 3000 cm−1 and beyond. We demonstrate reliable and efficient operation of a coherent anti-Stokes Raman spectroscopy and microscopy setup using this supercontinuum source.
Karenia brevis allelopathy compromises the lipidome, membrane integrity, and photosynthesis of competitors
Authors: Poulin Remington X. , Hogan Scott , Poulson-Ellestad Kelsey L. , Brown Emily , Fernández Facundo M. , Kubanek Julia
Published: June 2018

The formation, propagation, and maintenance of harmful algal blooms are of interest due to their negative effects on marine life and human health. Some bloom-forming algae utilize allelopathy, the release of compounds that inhibit competitors, to exclude other species dependent on a common pool of limiting resources. Allelopathy is hypothesized to affect bloom dynamics and is well established in the red tide dinoflagellate Karenia brevis. K. brevis typically suppresses competitor growth rather than being acutely toxic to other algae. When we investigated the effects of allelopathy on two competitors, Asterionellopsis glacialis and Thalassiosira pseudonana, using nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS)-based metabolomics, we found that the lipidomes of both species were significantly altered. However, A. glacialis maintained a more robust metabolism in response to K. brevis allelopathy whereas T. pseudonana exhibited significant alterations in lipid synthesis, cell membrane integrity, and photosynthesis. Membrane-associated lipids were significantly suppressed for T. pseudonana exposed to allelopathy such that membranes of living cells became permeable. K. brevis allelopathy appears to target lipid biosynthesis affecting multiple physiological pathways suggesting that exuded compounds have the ability to significantly alter competitor physiology, giving K. brevis an edge over sensitive species.
Strategies for screening young stock for antibodies – optimising numbers to test, cut-points, & predictive values for bovine viral diarrhoea virus
Authors: Humphry R. W. , Reeves A. , Gunn G. J.
Published: June 2018

The antibody seroprevalence of young stock can be a useful indicator of recent or current infection in a herd. We examine the factors that contribute to the assessment of herd exposure to disease, via spot testing for antibody, using bovine viral diarrhoea virus (BVDv) as an example. A statistical distribution of seroprevalences for BVDv in beef herds identified three groups of herds: low, intermediate and high within-herd BVDv antibody seroprevalence. We tested two assumptions –the intermediate seroprevalence group of herds is assumed to be negative for BVDv at the herd level and alternatively if this group is assumed to be positive. We found that: The herd-level sensitivity and specificity are sensitive to the assumption regarding the herds with intermediate seroprevalence. If an appropriate cut-point is chosen, reducing the sample size from ten to five does not produce a large drop in herd-level test performance. Increasing the cut-point may be valuable at the outset of an eradication programme. Increasing the sample size and decreasing the cut-point is advantageous towards the end of an eradication programme, to minimise the risk of positive herds being misclassified. The framework presented here illustrates how seroprevalence screening may be understood and assessed.
Thermal inactivation kinetics and effects of drying methods on the phenolic profile and antioxidant activities of chicory (Cichorium intybus L.) leaves
Authors: Li Ran , Shang Hongmei , Wu Hongxin , Wang Menghan , Duan Mengying , Yang Junyan
Published: June 2018

The thermal inactivation kinetics of enzymes, including polyphenol oxidase (PPO) and peroxidase (POD), in chicory (Cichorium intybus L.) leaves were evaluated. In addition, the influences of different drying techniques (shade drying, hot air drying and freeze drying) on the phenolic profiles and antioxidant activities of chicory leaves were determined. The antioxidant activities of chicory leaves were evaluated on the basis of their 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, reducing power, and 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity. The results showed that the activation energy for PPO and POD inactivation were 123.00 kJ/mol and 78.99 kJ/mol, respectively. Preliminary treatment with hot water for 3 min at 90 °C was beneficial for preserving the phenolics present in fresh leaves. Hot air drying was better for the phenolics preservation. The hot air-dried and freeze-dried leaves possessed good antioxidant activities. The leaves with higher phenolics contents had better antioxidant activities, which indicated that the preservation of the phenolics was important for maintaining the antioxidant activity of chicory leaves.
Twist of Tubular Mechanical Metamaterials Based on Waterbomb Origami
Authors: Feng Huijuan , Ma Jiayao , Chen Yan , You Zhong
Published: June 2018

Origami-inspired mechanical metamaterials have recently drawn increasing attention since their flexible mechanical performance has been greatly enhanced by introducing origami patterns to the thin-shell structures. As a typical origami pattern, the waterbomb tube could be adopted to the design of mechanical metamaterials. However, existing designs predominantly make use of the radial expansion/contraction motion of the structure, thereby limiting its full potential to be explored. Here we report a twist motion of tubular mechanical metamaterials based on waterbomb origami that is previously undiscovered. We demonstrate through a detailed kinematic analysis that the initial twist is a rigid-origami motion if the corresponding row of the tube under twist is fully squeezed with both line and plane symmetry, whereas all the subsequent twist motion requires material deformation. The twist angle per axial strain and its relationship with the geometrical parameters of the tube are revealed. Experimental results show the enhancement in stiffness of the tube with the occurrence of the continuous twist motion. We envisage that this finding could greatly expand the application of the waterbomb tube in the design of origami metamaterials with programmable and tuneable mechanical properties.
A key process of the nonstationary relationship between ENSO and the Western Pacific teleconnection pattern
Authors: Park Young-Hyang , Kim Baek-Min , Pak Gyundo , Yamamoto Masaru , Vivier Frédéric , Durand Isabelle
Published: June 2018

Recent studies have discovered an intriguing nonstationary relationship between El Ninõ–Southern Oscillation (ENSO) and the Western Pacific (WP) teleconnection pattern, one of the most prominent winter atmospheric circulation patterns in the North Pacific, with a regime-dependent interdecadal modulation of significant and insignificant correlations. However, the physical process underlying the observed nonstationary ENSO-WP relationship is a puzzle and remains to be elucidated, which is also essential for clarifying the still-debated nontrivial issue on whether the WP is directly forced by ENSO or by midlatitude storm tracks-driven intrinsic processes. Based on empirical orthogonal function (EOF) analysis of the upper-tropospheric teleconnection patterns and associated Rossby wave sources (RWS), we show that the nonstationarity in question is due to the regime-dependent constructive or destructive interference in meridional overturning circulation between the two leading EOFs of RWS best correlated with ENSO and WP, respectively. The observed insignificant correlation between ENSO and the WP after the 1988 regime shift can be explained by interrupted teleconnection between the tropics and high latitudes due to the collapse of the subtropical bridge pillar in the jet entrance region, consequence of the destructive interference. This suggested interference mechanism related to the regime-dependent upper-level RWS fields has significant implications for resolving the puzzle that hinders better understanding of decadal regime behaviors of the climate system in the North Pacific.
HIF stabilization inhibits renal epithelial cell migration and is associated with cytoskeletal alterations
Authors: Müller Simon , Djudjaj Sonja , Lange Janina , Iacovescu Mihail , Goppelt-Struebe Margarete , Boor Peter
Published: June 2018

Acute kidney injury (AKI) is a common and potentially lethal complication in the hospitalized patients, with hypoxic injury being as a major cause. The loss of renal tubular epithelial cells (TEC), one of the AKI hallmarks, is potentially followed by tubular regeneration process orchestrated by the remaining uninjured TECs that undergo proliferation and migration. In this study, we used human primary TEC to investigate the initiation of tubular cell migration and associated cytoskeletal alterations in response to pharmacological HIF stabilization which resembles the pathophysiology of hypoxia. Tubular cells have been shown to migrate as cohorts in a wound healing assay. Importantly, cells of distal tubular origin moved faster than those of proximal origin. HIF stabilization impaired TEC migration, which was confirmed by live single cell tracking. HIF stabilization significantly reduced tubular cell migration velocity and promoted cell spreading. In contrast to the control conditions, HIF stabilization induced actin filaments rearrangement and cell adhesion molecules including paxillin and focal adhesion kinase. Condensed bundling of keratin fibers was also observed, while the expression of different types of keratins, phosphorylation of keratin 18, and the microtubule structure were not altered. In summary, HIF stabilization reduced the ability of renal tubular cells to migrate and led to cytoskeleton reorganization. Our data suggested an important involvement of HIF stabilization during the epithelial migration underlying the mechanism of renal regeneration in response to AKI.
Linear Cyclodextrin Polymer Prodrugs as Novel Therapeutics for Niemann-Pick Type C1 Disorder
Authors: Kulkarni Aditya , Caporali Paola , Dolas Atul , Johny Soniya , Goyal Sandeep , Dragotto Jessica , Macone Alberto , Jayaraman Ramesh , Fiorenza Maria Teresa
Published: June 2018

Niemann-Pick Type C1 disorder (NPC) is a rare lysosomal storage disease characterized by the accumulation of cholesterol in lysosomes. NPC has no FDA approved treatments yet, however 2-hydroxypropyl-β-cyclodextrin (HPβCD) has shown efficacy for treating the disease in both mouse and feline NPC models and is currently being investigated in late stage clinical trials. Despite promising results, therapeutic use of HPβCD is limited by the need for high doses, ototoxicity and intrathecal administration. These limitations can be attributed to its poor pharmacokinetic profile. In the attempt to overcome these limitations, we have designed a β-cyclodextrin (βCD) based polymer prodrugs (ORX-301) for an enhanced pharmacokinetic and biodistribution profile, which in turn can potentially provide an improved efficacy at lower doses. We demonstrated that subcutaneously injected ORX-301 extended the mean lifespan of NPC mice at a dosage 5-fold lower (800 mg/kg, body weight) the HPβCD dose proven efficacious (4000 mg/kg). We also show that ORX-301 penetrates the blood brain barrier and counteracts neurological impairment. These properties represent a substantial improvement and appear to overcome major limitations of presently available βCD-based therapy, demonstrating that this novel prodrug is a valuable alternative/complement for existing therapies.
Frustrated Lewis pairs in ionic liquids and molecular solvents – a neutron scattering and NMR study of encounter complexes
Authors: Brown Lucy C. , Hogg James M. , Gilmore Mark , Moura Leila , Imberti Silvia , Gärtner Sabrina , Gunaratne H. Q. Nimal , O’Donnell Ruairi J. , Artioli Nancy , Holbrey John D. , Swadźba-Kwaśny Małgorzata
Published: June 2018

Encounter complexes of a frustrated lewis pair are more stable and prevalent in an ionic liquid than in benzene.
Bicycloaromaticity and Baird-type bicycloaromaticity of dithienothiophene-bridged [34]octaphyrins
Authors: Valiev Rashid R. , Fliegl Heike , Sundholm Dage
Published: June 2018

Current density calculations on dithienothiophene-bridged [34]octaphyrins reveal difficulties to experimentally determine the aromatic character when NMR spectra are not available.
Understanding the chemoselectivities between carbonyl and hydroxyl groups in the Rh(ii)–azavinyl carbene involved reactions
Authors: Lv Yuanzheng , Ogunlana Abosede Adejoke , Li Hongli , Gao Dafang , Wang Chenli , Bao Xiaoguang
Published: June 2018

Computational studies were carried out to understand the chemoselectivities between carbonyl and hydroxyl groups in the Rh(ii)–AVC involved reactions.
Electrochemically prepared oxides for resistive switching memories
Authors: Zaffora A. , Di Quarto F. , Habazaki H. , Valov I. , Santamaria M.
Published: June 2018

Electrochemically grown anodic oxides of different compositions and properties were tested as solid electrolytes for resistive switching memories.
New bow-tie cationic carbosilane dendritic system with a curcumin core as an anti-breast cancer agent
Authors: Lozano-Cruz Tania , Gómez Rafael , de la Mata F. Javier , Ortega Paula
Published: June 2018

A water soluble “bow-tie” cationic carbosilane dendrimer with curcumin in the core displays antioxidant and antitumoral activities against breast cancer cells.
Preparation of Co–N carbon nanosheet oxygen electrode catalyst by controlled crystallization of cobalt salt precursors for all-solid-state Al–air battery
Authors: Shen Jianhua , Meng Lu , Liu Yanyan , Chen Cheng , Zhu Yihua , Li Chunzhong
Published: June 2018

Production of bifunctional catalysts for catalyzing both ORR and OER is highly advisable but challenging with respect to the applications of these catalysts in renewable energy conversion and storage technologies.
Study of the structure and characteristics of mesoporous TiO2 photocatalyst, and evaluation of its factors on gaseous formaldehyde removal by the analysis of ANOVA and S/N ratio
Authors: Lee Shiuan-Shinn , Lu Chi-Yuan , Wu Min-Chang
Published: June 2018

This study differs from previous studies of TiO2/SiO2 in that 0.5–10 μm microsized TiO2-rutile based catalysts (TR catalysts) with varying proportions of titanium and silicon were synthesized using a one-step modified hydrothermal method.
Systems analysis of metabolism in platelet concentrates during storage in platelet additive solution
Authors: Jóhannsson Freyr , Guðmundsson Steinn , Paglia Giuseppe , Guðmundsson Sveinn , Palsson Bernhard , Sigurjónsson Ólafur E. , Rolfsson Óttar
Published: June 2018

Platelets (PLTs) deteriorate over time when stored within blood banks through a biological process known as PLT storage lesion (PSL). Here, we describe the refinement of the biochemical model of PLT metabolism, iAT-PLT-636, and its application to describe and investigate changes in metabolism during PLT storage. Changes in extracellular acetate and citrate were measured in buffy coat and apheresis PLT units over 10 days of storage in the PLT additive solution T-Sol. Metabolic network analysis of these data was performed alongside our prior metabolomics data to describe the metabolism of fresh (days 1–3), intermediate (days 4–6), and expired (days 7–10) PLTs. Changes in metabolism were studied by comparing metabolic model flux predictions of iAT-PLT-636 between stages and between collection methods. Extracellular acetate and glucose contribute most to central carbon metabolism in PLTs. The anticoagulant citrate is metabolized in apheresis-stored PLTs and is converted into aconitate and, to a lesser degree, malate. The consumption of nutrients changes during storage and reflects altered PLT activation profiles following their collection. Irrespective of the collection method, a slowdown in oxidative phosphorylation takes place, consistent with mitochondrial dysfunction during PSL. Finally, the main contributors to intracellular ammonium and NADPH are highlighted. Future optimization of flux through these pathways provides opportunities to address intracellular pH changes and reactive oxygen species, which are both of importance to PSL. The metabolic models provide descriptions of PLT metabolism at steady state and represent a platform for future PLT metabolic research.
Vinylation of Benzylic Amines via C–N Bond Functionalization of Benzylic Pyridinium Salts
Authors: Watson Mary , Guan Weiye , Liao Jennie
Published: June 2018

Cross-couplings of benzylic pyridinium salts and vinylboronic acids or esters have been developed. Via benzylic pyridinium intermediates, benzylic amines can be engaged in these cross-couplings through C–N bond functionalization. This method boasts mild reaction conditions and excellent tolerance for heteroaryl substituents and a range of functional groups.
Synthetic Strategies for the Regioselective Functionalization of Tribenzotriquinacenes
Authors: Beuerle Florian , Dhara Ayan
Published: June 2018

The rigid molecular scaffold of the tribenzotriquinacenes (TBTQs) has emerged as a versatile structural platform that possesses unique geometrical features and allows for an orthogonal arrangement of organic functional substituents or convex-concave interactions. In this review, we summarize and discuss important synthetic strategies for a regioselective functionalization at the four distinct positions of the TBTQ basic framework, namely, apical, bridgehead, ortho, and outer rim.

1 Introduction

2 Structure and Synthesis of TBTQs

3 Bridgehead Functionalization

4 Outer Rim Functionalization

5 ortho-Functionalization

6 Apical Functionalization

7 Conclusion and Outlook
SOP beim akuten Koronarsyndrom – Update 2018
Authors: Möckel Martin
Published: June 2018

In den Leitlinien zum akuten Koronarsyndrom (ACS) sind die Behandlungsoptionen, aber auch die Notwendigkeit der Netzwerkbildung zwischen den Bereichen der Versorgung festgeschrieben. Wir beschäftigen uns in diesem Beitrag mit der Umsetzung der Leitlinien in krankenhausbezogene SOP am Beispiel des ST-Hebungsinfarkts (STEMI).
Gauss-Bonnet for matrix conformally rescaled Dirac
Authors: Khalkhali Masoud , Sitarz Andrzej
Published: June 2018

We derive an explicit formula for the scalar curvature over a two-torus with a Dirac operator conformally rescaled by a globally diagonalizable matrix. We show that the Gauss-Bonnet theorem holds and extends the result to all Riemann surfaces with Dirac operators modified in the same way.
Non-Abelian geometric phases carried by the spin fluctuation tensor
Authors: H. M Bharath
Published: June 2018

The expectation values of the first and second moments of the quantum mechanical spin operator can be used to define a spin vector and spin fluctuation tensor, respectively. The former is a vector inside the unit ball in three space, while the latter is represented by an ellipsoid in three space. They are both experimentally accessible in many physical systems. By considering transport of the spin vector along loops in the unit ball, it is shown that the spin fluctuation tensor picks up geometric phase information. For the physically important case of spin one, the geometric phase is formulated in terms of an SO(3) operator. Loops defined in the unit ball fall into two classes: those which do not pass through the origin and those which pass through the origin. The former class of loops subtend a well-defined solid angle at the origin, while the latter do not, and the corresponding geometric phase is non-Abelian. To deal with both classes, a notion of generalized solid angle is introduced, which helps to clarify the interpretation of the geometric phase information. The experimental systems that can be used to observe this geometric phase are also discussed.
Structured ultrasound microscopy
Authors: Janjic Jovana , Kruizinga Pieter , van der Meulen Pim , Springeling Geert , Mastik Frits , Leus Geert , Bosch Johan G. , van der Steen Antonius F. W. , van Soest Gijs
Published: June 2018

We present a form of acoustic microscopy, called Structured Ultrasound Microscopy (SUM). It creates a volumetric image by recording reflected echoes of ultrasound waves with a structured phase front using a moving single-element transducer and computational reconstruction. A priori knowledge of the acoustic field produced by the single element allows us to relate the received echoes to a 3D scatter map within the acoustic beam itself, leading to an isotropic resolution at all depths. An aberration mask in front of the acoustic element imposes the phase structure, broadening the beam and breaking the spatial coherence between different voxels at equal acoustic propagation delay, increasing the uniqueness of the reconstruction. By translating the transducer across the 3D volume, we synthetically enlarge the imaging aperture by using multiple overlapping and spatially sparsely sampled measurements to solve for the entire image. In this paper, we explain the SUM technique and demonstrate microscopic imaging at 20 MHz of a 2.3 × 2.3 × 1.2 mm object in water, with an isotropic resolution below 100 μm. The proposed approach allows for wide-field 3D imaging at isotropic microscopic resolution using a small unfocused ultrasound sensor and multiple spatially sparsely sampled measurements. This technique may find applications in many other fields where space is constrained, device simplicity is desired, and wide-field isotropic high-resolution imaging is required.
Evolutionary strategy for inverse charge measurements of dielectric particles
Authors: Jiang Xikai , Li Jiyuan , Lee Victor , Jaeger Heinrich M. , Heinonen Olle G. , de Pablo Juan J.
Published: June 2018

We report a computational strategy to obtain the charges of individual dielectric particles from experimental observation of their interactions as a function of time. This strategy uses evolutionary optimization to minimize the difference between trajectories extracted from the experiment and simulated trajectories based on many-particle force fields. The force fields include both Coulombic interactions and dielectric polarization effects that arise due to particle-particle charge mismatch and particle-environment dielectric contrast. The strategy was applied to systems of free falling charged granular particles in a vacuum, where electrostatic interactions are the only driving forces that influence the particles’ motion. We show that when the particles’ initial positions and velocities are known, the optimizer requires only an initial and final particle configuration of a short trajectory in order to accurately infer the particles’ charges; when the initial velocities are unknown and only the initial positions are given, the optimizer can learn from multiple frames along the trajectory to determine the particles’ initial velocities and charges. While the results presented here offer a proof-of-concept demonstration of the proposed ideas, the proposed strategy could be extended to more complex systems of electrostatically charged granular matter.
First D+D neutron image at the National Ignition Facility
Authors: Volegov P. L. , Wilson D. C. , Dewald E. L. , Berzak Hopkins L. F. , Danly C. R. , Fatherley V. E. , Geppert-Kleinrath V. , Merrill F. E. , Simpson R. , Wilde C. H. , Fittinghoff D. N. , Casey D. T. , Grim G. P. , Ayers M. J. , Hatarik R. , Yeamans C. B. , Kruse M. K. G. , Sayre D. B. , Munro D. , Le Pape S. , Izumi N. , Batha S. H.
Published: June 2018

First time-integrated neutron images of a deuterium gas filled capsule were obtained using arrival time gating with the Neutron Imaging System at the National Ignition Facility. Images exist from DT (deuterium and tritium mixture) filled capsules in several energy bands but only at the Omega laser had DD (pure deuterium) filled capsules been imaged. A composite image was derived from an assembly of multiple penumbral neutron images using an iterative Maximum Likelihood reconstruction technique. This was compared with a simulated image from a radiation-hydrodynamic calculation. The observed image size, and shape agree, as do the primary DD, secondary DT neutron yields, and the burn duration. However, the observed cross-sectional profiles, although smaller in half width, extend outside the calculated, suggesting that deuterium has mixed outward into the carbon ablator. The observed X-ray image size (61 μm) is larger than the observed neutron image (51 μm). The calculations also reflect this. X-ray brightness includes carbon as well as deuterium emission. A bright spot, “meteor,” in the X-ray image is seen to move in time-gated images, but is not evident in the neutron image. It does not appear to degrade the neutron yield.
Integration of graphene oxide buffer layer/graphene floating gate for wide memory window in Pt/Ti/Al2O3/GO/graphene/SiO2/p-Si/Au non-volatile (FLASH) applications
Authors: Soni Mahesh , Soni Ajay , Sharma Satinder K.
Published: June 2018

The excellent electronic properties of graphene such as high density of states, work-function, and low dimensionality promote the usage of graphene as an efficient floating gate (FG) layer for downscaled, high density non-volatile flash memories (NVFMs). However, the chemical inertness of graphene requires a buffer layer for the uniform deposition of a high-k blocking layer (high-k blocking oxide/buffer layer/graphene/SiO2/p-Si/Au). Herein, FG-NVFM devices are fabricated using few-layer graphene as a FG followed by deposition of spin-coated monolayer graphene oxide (GO) as a buffer layer. The simple, stress free deposition of GO decorated with the functional groups is anticipated for the uniform deposition of blocking oxide (Aluminum oxide, Al2O3) over GO/graphene/SiO2/p-Si/Au. Beyond this, it improves the interface (Al2O3/GO/graphene), leading to enhanced memory characteristics for the fabricated Pt/Ti/Al2O3/GO/graphene/SiO2/p-Si/Au FG-NVFM structure. The electrical characterizations of the fabricated FG-NVFM devices show a significantly wide memory window of ∼4.3 V @ ±7 V at 1 MHz and robust retention up to ∼2 × 1013 s (>15 years). These observations clearly reveal an efficient potential of graphene for FG and GO as a buffer layer for the future NVFM device applications.
Demonstration of forward cascaded Brillouin lasing using a silicon-based rectangular spiral microring resonator assisted by EDFA
Authors: Zhang Ruiwen , Sun Junqiang , Cheng Ming , Wang Kang
Published: June 2018

We experimentally demonstrate the forward cascaded Brillouin lasing exploiting a silicon-based rectangular spiral microring resonator assisted by an erbium-doped fiber amplifier. To realize the enhanced Brillouin nonlinearity, the optical and acoustic fields are effectively confined by partly suspending the spiral resonator. The free spectral range is precisely designed to match the half of the Brillouin frequency shift to guarantee Brillouin laser oscillation. The fabricated spiral resonator is incorporated in a fiber loop to serve as not only a resonance-enhanced element to generate the internal pump lasing for Brillouin scattering but also a Brillouin gain medium to excite Brillouin lasing. The spiral structure allows a 0.6368 cm long resonator waveguide to be enclosed in a small footprint of 250 × 330 μm2. Four anti-Stokes and three Stokes lasing lines are obtained with the Brillouin frequency shift of about 12.0463 GHz. The proposed approach provides a potential way to implement Brillouin lasing on a silicon-based chip.
Novel compounds of cerium binary alloys from high-throughput first-principles calculations
Authors: Sun Xiaorui , Lei Yawei , Zhou Rulong , Zhang Bo
Published: June 2018

We report on a comprehensive study of 19 binary systems of cerium (Ce) and 4d or 5d transition metals involving high-throughput first-principles calculations. For Ce–Y, Ce–Zr, Ce–Nb, Ce–Mo, Ce–Hf, Ce–Ta, Ce–W, and Ce–Re, the computations and experiments agree that no compounds can form. However, for Ce–Tc and Ce–Au, the computations predict that stable compounds can form, although none have yet been synthesized experimentally. Regarding other possible systems, in addition to known compounds, a few dozen as-yet unreported compounds are predicted. For some systems, our calculations also identify novel crystalline structures with higher energetic stabilities compared to the corresponding experimentally reported structure at some particular compositions. According to the electronic-structure calculations, there is definite hybridization between the 4d or 5d electron states of the transition metals (i.e., with Tc, Ru, Rh, Pd, Os, Ir, and Pt) and the 4f electron states of Ce, whereas it is much weaker in Ce–Ag, Ce–Cd, Ce–Au, and Ce–Hg. Moreover, the elastic properties of these compounds are given. This systematic study offers new data for Ce-based alloys and will guide future studies of these important systems.
Impact of temperature and gamma radiation on electron diffusion length and mobility in p-type InAs/GaSb superlattices
Authors: Lee Jonathan , Fredricksen Chris J. , Flitsiyan Elena , Peale Robert E. , Chernyak Leonid , Taghipour Zahra , Casias Lilian , Kazemi Alireza , Krishna Sanjay , Myers Stephen
Published: June 2018

The minority carrier diffusion length was directly measured by the variable-temperature Electron Beam-Induced Current technique in InAs/GaSb type-II strain-layer-superlattice infrared-detector structures. The Molecular Beam Epitaxy-grown midwave infrared superlattices comprised 10 monolayers of InAs and 10 monolayers of GaSb to give a total absorber thickness of 4 μm. The diffusion length of minority electrons in the p-type absorber region of the p-type/barrier/n-type structure was found to increase from 1.08 to 2.24 μm with a thermal activation energy of 13.1 meV for temperatures ranging from 77 to 273 K. These lengths significantly exceed the individual 10-monolayer thicknesses of the InAs and GaSb, possibly indicating a low impact of interface scattering on the minority carrier diffusion length. The corresponding minority electron mobility varied from 48 to 65 cm2/V s. An absorbed gamma irradiation dose of 500 Gy halved the minority carrier diffusion length and increased the thermal activation energy to 18.6 meV, due to creation of radiation-induced defect recombination centers.
Brønsted Acid-Catalysed Allylic Amination of 1-(2-Aminoaryl)prop-2-en-1-ols to 1,2-Dihydroquinolines
Authors: Day David Philip , Henry Stuart Adam , Zhao Yichao , Jin Jianwen , Clarkson Guy James , Chan Philip Wai Hong
Published: June 2018

A highly efficient synthetic method to prepare 1,2-dihydroquinolines that relies on trifluoromethanesulfonic acid (TfOH)-catalysed allylic amination of 1-(2-aminoaryl)prop-2-en-1-ols is described. Achieved at a catalyst loading of 0.01 mol-% under mild conditions at room temperature, the reaction was found to be robust, with a wide range of substitution patterns tolerated. The corresponding N-heterocyclic adducts were obtained in good to excellent yields of 45–93 %.
Early loss of mitochondrial complex I and rewiring of glutathione metabolism in renal oncocytoma
Authors: Gopal Raj K. , Calvo Sarah E. , Shih Angela R. , Chaves Frances L. , McGuone Declan , Mick Eran , Pierce Kerry A. , Li Yang , Garofalo Andrea , Van Allen Eliezer M. , Clish Clary B. , Oliva Esther , Mootha Vamsi K.
Published: June 2018

Significance

Renal oncocytomas are benign kidney tumors with numerous mitochondria. Here, we analyze the mitochondrial (mtDNA) and nuclear genomes of these tumors. Our analysis finds mtDNA mutations in complex I (the first step in mitochondrial respiration) to be early genetic events that likely contribute to tumor formation. Since mtDNA mutations can lead to severe degenerative disorders, the cellular responses allowing renal oncocytoma cells to grow are important to consider. To properly understand authentic gene expression changes in tumors, we found it important to consider the gene expression pattern of the tumor’s cell of origin, the distal nephron. By doing so, we uncover alterations in glutathione synthesis and turnover that likely represent an adaptive metabolic response in renal oncocytoma.
Lack of group-to-individual generalizability is a threat to human subjects research
Authors: Fisher Aaron J. , Medaglia John D. , Jeronimus Bertus F.
Published: June 2018

Significance

The current study quantified the degree to which group data are able to describe individual participants. We utilized intensive repeated-measures data—data that have been collected many times, across many individuals—to compare the distributions of bivariate correlations calculated within subjects vs. those calculated between subjects. Because the vast majority of social and medical science research aggregates across subjects, we aimed to assess how closely such aggregations reflect their constituent individuals. We provide evidence that conclusions drawn from aggregated data may be worryingly imprecise. Specifically, the variance in individuals is up to four times larger than in groups. These data call for a focus on idiography and open science that may substantially alter best-practice guidelines in the medical and behavioral sciences.
Quasicrystalline 30° twisted bilayer graphene as an incommensurate superlattice with strong interlayer coupling
Authors: Yao Wei , Wang Eryin , Bao Changhua , Zhang Yiou , Zhang Kenan , Bao Kejie , Chan Chun Kai , Chen Chaoyu , Avila Jose , Asensio Maria C. , Zhu Junyi , Zhou Shuyun
Published: June 2018

Significance

Interlayer interaction in van der Waals heterostructures could induce many exotic phenomena. Unlike commensurate heterostructures, incommensurate ones have often been neglected, due to the rarity in nature and the assumption of suppressed coherent interlayer movement of electrons. How the interlayer interaction affects the electronic structure of such a nonperiodic heterostructure is a fundamental question. In this work, by successfully growing 30°-twisted bilayer graphene (tBLG) as an example for incommensurate “heterostructure” with quasicrystalline order, we report the emergence of mirrored Dirac cones. We identify that these mirrored Dirac cones are a consequence of the interlayer interaction, showing its importance in the incommensurate structure, which has been overlooked before. These results broaden the application range of van der Waals heterostructure for future electronic devices.
Global hidden harvest of freshwater fish revealed by household surveys
Authors: Fluet-Chouinard Etienne , Funge-Smith Simon , McIntyre Peter B.
Published: June 2018

Significance

Experts have long believed that fish catches from rivers and lakes are underreported, which leads to lack of appreciation for their contribution to global food security. Rather than focusing on landing data, we backcalculated harvests using surveys of household consumption of freshwater fish. Data from 548,000 households across 42 countries reveal that freshwater catches are likely to be ∼65% higher than officially reported. These hidden harvests are concentrated in low-income countries where they represent the equivalent of the total annual animal protein consumption of 36.9 million people. Long-term underreporting of inland fisheries masks their critical role in feeding the world’s poor and complicates using catch statistics to evaluate the impact of overharvest and ecosystem degradation.
Declining mental health among disadvantaged Americans
Authors: Goldman Noreen , Glei Dana A. , Weinstein Maxine
Published: June 2018

Significance

In the past few years, references to the opioid epidemic, drug poisonings, and associated feelings of despair among Americans, primarily working-class whites, have flooded the media, and related patterns of mortality have been of increasing interest to social scientists. Yet, despite recurring references to distress or despair in journalistic accounts and academic studies, there has been little analysis of whether psychological health among American adults has worsened over the past two decades. Here, we use data from national samples of adults in the mid-1990s and early 2010s to demonstrate increasing distress and declining well-being that was concentrated among low-socioeconomic-status individuals but spanned the age range from young to older adults.
Rsd balances (p)ppGpp level by stimulating the hydrolase activity of SpoT during carbon source downshift in
Escherichia coli
Authors: Lee Jae-Woo , Park Young-Ha , Seok Yeong-Jae
Published: June 2018

Significance

Most bacteria accumulate the molecular alarmone (p)ppGpp to divert resources away from growth and division toward biosynthesis under various nutrient limitations. Despite its crucial role, uncontrolled accumulation of this alarmone causes severe growth inhibition and cell death. Thus, fine-tuning the cellular (p)ppGpp level is required to ensure survival and adaptation under harsh nutritional conditions. Here, we identify Rsd as a stimulator of the (p)ppGpp-degrading activity of SpoT during carbon source downshift in
Escherichia coli
, and this regulation is controlled by the phosphorylation state of HPr, a general component of the PEP-dependent sugar transport system. This study establishes a direct link between sugar signaling and the bacterial stringent response.
Ultrahigh-charge electron beams from laser-irradiated solid surface
Authors: Ma Yong , Zhao Jiarui , Li Yifei , Li Dazhang , Chen Liming , Liu Jianxun , Dann Stephen J. D. , Ma Yanyun , Yang Xiaohu , Ge Zheyi , Sheng Zhengming , Zhang Jie
Published: June 2018

Significance

In the last three decades, the laser–plasma accelerator (LPA) has shown a rapid development owing to its super–high-accelerate gradients, which makes it a very promising compact accelerator and light source. Acceleration of a high-quality electron beam with divergence angle as small as possible and beam charge as high as possible has been a long-term goal ever since the inception of the LPA concept. However, until now the most popular acceleration scenario has failed to achieve both goals. We solved this problem and obtained tightly collimated electron beams with small divergence angle and extremely high beam charge (

∼

100 nC) via the powerful

p
s

laser pulse interacting with a solid target.
RalA controls glucose homeostasis by regulating glucose uptake in brown fat
Authors: Skorobogatko Yuliya , Dragan Morgan , Cordon Claudia , Reilly Shannon M. , Hung Chao-Wei , Xia Wenmin , Zhao Peng , Wallace Martina , Lackey Denise E. , Chen Xiao-Wei , Osborn Olivia , Bogner-Strauss Juliane G. , Theodorescu Dan , Metallo Christian M. , Olefsky Jerrold M. , Saltiel Alan R.
Published: June 2018

Significance

The primary event in diabetes pathogenesis is the development of insulin resistance. Insulin is elevated during feeding and maintains blood glucose levels within a physiological range, largely by increasing glucose uptake in muscle and fat. Our laboratory has identified two components of insulin signaling, the protein RalA and its GAP complex RalGAP, which regulate glucose uptake by fat cells. Using genetic approaches and pharmacological inhibitors, we describe how these proteins influence glucose metabolism in mice. We discovered that RalA is essential for efficient insulin-stimulated glucose uptake in fat, while RalA activation via deletion of RalGAP dramatically increases glucose uptake into brown fat and improves glucose handling in mice (hence, protecting them from developing diabetes).
Separating the effects of nucleotide and EB binding on microtubule structure
Authors: Zhang Rui , LaFrance Benjamin , Nogales Eva
Published: June 2018

Significance

We report three high-resolution structures of microtubules in different nucleotide states—GMPCPP, GDP, and GTPγS—in the absence of any binding proteins, allowing us to separate the effects of nucleotide- and microtubule (MT)-associated protein (MAPs) binding on MT structure. End-binding (EB) proteins can bind and induce partial lattice compaction of a preformed GMPCPP-bound MT, a lattice type that is far from EBs’ ideal binding platform. We propose a model in which the MT lattice serves as a platform that integrates internal tubulin signals, such as nucleotide state, with outside signals, such as binding of MAPs. These global lattice rearrangements in turn affect the affinity of other MT partners and result in the exquisite regulation of the MT dynamics.