bluuebunny/crossref_metadata_2025 huggingface dataset:
The Observed Seasonal Cycle of Macronutrients in Drake Passage: Relationship to Fronts and Utility as a Model Metric
Authors: Freeman Natalie M. , Munro David R. , Sprintall Janet , Mazloff Matthew R. , Purkey Sarah , Rosso Isabella , DeRanek Carissa A. , Sweeney Colm
Published: May 2019

The Drake Passage Time‐series (DPT) is used to quantify the spatial and seasonal variability of historically undersampled, biogeochemically relevant properties across the Drake Passage. From 2004–2017, discrete ship‐based observations of surface macronutrients (silicate, nitrate, and phosphate), temperature, and salinity have been collected 5–8 times per year as part of the DPT program. Using the DPT and Antarctic Circumpolar Current (ACC) front locations derived from concurrent expendable bathythermograph data, the distinct physical and biogeochemical characteristics of ACC frontal zones are characterized. Biogeochemical‐Argo floats in the region confirm that the near‐surface sampling scheme of the DPT robustly captures mixed‐layer biogeochemistry. While macronutrient concentrations consistently increase toward the Antarctic continent, their meridional distribution, variability, and biogeochemical gradients are unique across physical ACC fronts, suggesting a combination of physical and biological processes controlling nutrient availability and nutrient front location. The Polar Front is associated with the northern expression of the Silicate Front, marking the biogeographically relevant location between silicate‐poor and silicate‐rich waters. South of the northern Silicate Front, the silicate‐to‐nitrate ratio increases, with the sharpest gradient in silicate associated with the Southern ACC Front (i.e., the southern expression of the Silicate Front). Nutrient cycling is an important control on variability in the surface ocean partial pressure of carbon dioxide (pCO2). The robust characterization of the spatiotemporal variability of nutrients presented here highlights the utility of biogeochemical time series for diagnosing and potentially reducing biases in modeling Southern Ocean pCO2 variability, and by inference, air‐sea CO2 flux.
Oridonin protects against cardiac hypertrophy by promoting P21-related autophagy
Authors: Xu Man , Wan Chun-xia , Huang Si-hui , Wang Hui-bo , Fan Di , Wu Hai-Ming , Wu Qing-qing , Ma Zhen-guo , Deng Wei , Tang Qi-Zhu
Published: May 2019

Autophagy is an endogenous protective process; the loss of autophagy could destabilize proteostasis and elevate intracellular oxidative stress, which is critically involved in the development of cardiac hypertrophy and heart failure. Oridonin, a natural tetracycline diterpenoid from the Chinese herb Rabdosia, has autophagy activation properties. In this study, we tested whether oridonin protects against cardiac hypertrophy in mice and cardiomyocytes. We implemented aortic banding to induce a cardiac hypertrophy mouse model, and oridonin was given by gavage for 4 weeks. Neonatal rat cardiomyocytes were stimulated with angiotensin II to simulate neurohumoural stress. Both in vivo and in vitro studies suggested that oridonin treatment mitigated pressure overload-induced cardiac hypertrophy and fibrosis, and also preserved heart function. Mice that received oridonin exhibited increased antioxidase activities and suppressed oxidative injury compared with the aortic banding group. Moreover, oridonin enhanced myocardial autophagy in pressure-overloaded hearts and angiotensin II-stimulated cardiomyocytes. Mechanistically, we discovered that oridonin administration regulated myocardial P21, and cytoplasmic P21 activated autophagy via regulating Akt and AMPK phosphorylation. These findings were further corroborated in a P21 knockout mouse model. Collectively, pressure overload-induced autophagy dysfunction causes intracellular protein accumulation, resulting in ROS injury while aggravating cardiac hypertrophy. Thus, our data show that oridonin promoted P21-related autophagic lysosomal degradation, hence attenuating oxidative injury and cardiac hypertrophy.
MiR-30 family prevents uPAR-ITGB3 signaling activation through calcineurin-NFATC pathway to protect podocytes
Authors: Lang Yue , Zhao Yue , Zheng Chunxia , Lu Yinghui , Wu Junnan , Zhu Xiaodong , Zhang Mingchao , Yang Fan , Xu Xiaodong , Shi Shaolin , Liu Zhihong
Published: May 2019

Urokinase plasminogen activator receptor (uPAR) is upregulated in podocytes of glomerular diseases and crucially mediates podocyte injury through integrin β3 (ITGB3). We previously showed that the miR-30 family maintains podocyte structure and function by inhibiting injurious calcineurin signaling through nuclear factor of activated T cells C (NFATC). Here, we tested whether the miR-30-calcineurin-NFATC and uPAR-ITGB3 pathways, two of the major pathways leading to podocyte injury, could interact. We found that podocyte-specific miR-30 knockdown in mice induced uPAR upregulation and ITGB3 activation, accompanied by proteinuria and podocyte injury. These effects of miR-30 knockdown were reduced using inhibitors of ITGB3, calcineurin, and NFATC, respectively, which are known to be antiproteinuric. These results indicate that miR-30 deficiency leads to calcineurin-NFATC signaling activation, which in turn activates the uPAR-ITGB3 pathway. In cultured podocytes, miR-30 knockdown also activated uPAR-ITGB3 signaling, leading to Rho GTPase activation, synaptopodin downregulation and podocyte injury. To explore uPAR-ITGB3 signaling regulation by miR-30 in podocytopathy development, we treated mice with lipopolysaccharide (LPS) and found that miR-30 was downregulated in podocytes, accompanied by uPAR upregulation and ITGB3 activation. We obtained the same results in cultured podocytes treated with LPS. Podocyte-specific transgenic miR-30 abolished uPAR-ITGB3 signaling and ameliorated podocyte injury and proteinuria in mice. Taken together, these experiments show that uPAR-ITGB3 signaling is negatively regulated by miR-30 through calcineurin-NFATC pathway, a novel mechanism underlying podocyte injury in glomerular diseases. Our study has elucidated the relationship among the crucial players governing podocyte pathophysiology and the antiproteinuric actions of drugs commonly used for podocytopathies.
Atomic dispensers for thermoplasmonic control of alkali vapor pressure in quantum optical applications
Authors: Rusimova Kristina R. , Slavov Dimitar , Pradaux-Caggiano Fabienne , Collins Joel T. , Gordeev Sergey N. , Carbery David R. , Wadsworth William J. , Mosley Peter J. , Valev Ventsislav K.
Published: May 2019

Alkali metal vapors enable access to single electron systems, suitable for demonstrating fundamental light-matter interactions and promising for quantum logic operations, storage and sensing. However, progress is hampered by the need for robust and repeatable control over the atomic vapor density and over the associated optical depth. Until now, a moderate improvement of the optical depth was attainable through bulk heating or laser desorption – both time-consuming techniques. Here, we use plasmonic nanoparticles to convert light into localized thermal energy and to achieve optical depths in warm vapors, corresponding to a ~16 times increase in vapor pressure in less than 20 ms, with possible reload times much shorter than an hour. Our results enable robust and compact light-matter devices, such as efficient quantum memories and photon-photon logic gates, in which strong optical nonlinearities are crucial.
Atomic resolution cryo-EM structure of a native-like CENP-A nucleosome aided by an antibody fragment
Authors: Zhou Bing-Rui , Yadav K. N. Sathish , Borgnia Mario , Hong Jingjun , Cao Baohua , Olins Ada L. , Olins Donald E. , Bai Yawen , Zhang Ping
Published: May 2019

Genomic DNA in eukaryotes is organized into chromatin through association with core histones to form nucleosomes, each distinguished by their DNA sequences and histone variants. Here, we used a single-chain antibody fragment (scFv) derived from the anti-nucleosome antibody mAb PL2-6 to stabilize human CENP-A nucleosome containing a native α-satellite DNA and solved its structure by the cryo-electron microscopy (cryo-EM) to 2.6 Å resolution. In comparison, the corresponding cryo-EM structure of the free CENP-A nucleosome could only reach 3.4 Å resolution. We find that scFv binds to a conserved acidic patch on the histone H2A-H2B dimer without perturbing the nucleosome structure. Our results provide an atomic resolution cryo-EM structure of a nucleosome and insight into the structure and function of the CENP-A nucleosome. The scFv approach is applicable to the structural determination of other native-like nucleosomes with distinct DNA sequences.
Direct dioxygen evolution in collisions of carbon dioxide with surfaces
Authors: Yao Yunxi , Shushkov Philip , Miller Thomas F. , Giapis Konstantinos P.
Published: May 2019

The intramolecular conversion of CO2 to molecular oxygen is an exotic reaction, rarely observed even with extreme optical or electronic excitation means. Here we show that this reaction occurs readily when CO2 ions scatter from solid surfaces in a two-step sequential collision process at hyperthermal incidence energies. The produced O2 is preferentially ionized by charge transfer from the surface over the predominant atomic oxygen product, leading to direct detection of both O2+ and O2−. First-principles simulations of the collisional dynamics reveal that O2 production proceeds via strongly-bent CO2 configurations, without visiting other intermediates. Bent CO2 provides dynamic access to the symmetric dissociation of CO2 to C+O2 with a calculated yield of 1 to 2% depending on molecular orientation. This unexpected collision-induced transformation of individual CO2 molecules provides an accessible pathway for generating O2 in astrophysical environments and may inspire plasma-driven electro- and photo-catalytic strategies for terrestrial CO2 reduction.
The stability of multitrophic communities under habitat loss
Authors: McWilliams Chris , Lurgi Miguel , Montoya Jose M. , Sauve Alix , Montoya Daniel
Published: May 2019

Habitat loss (HL) affects species and their interactions, ultimately altering community dynamics. Yet, a challenge for community ecology is to understand how communities with multiple interaction types—hybrid communities—respond to HL prior to species extinctions. To this end, we develop a model to investigate the response of hybrid terrestrial communities to two types of HL: random and contiguous. Our model reveals changes in stability—temporal variability in population abundances—that are dependent on the spatial configuration of HL. Our findings highlight that habitat area determines the variability of populations via changes in the distribution of species interaction strengths. The divergent responses of communities to random and contiguous HL result from different constraints imposed on individuals’ mobility, impacting diversity and network structure in the random case, and destabilising communities by increasing interaction strength in the contiguous case. Analysis of intermediate HL suggests a gradual transition between the two extreme cases.
Hong-Ou-Mandel interferometry on a biphoton beat note
Authors: Chen Yuanyuan , Fink Matthias , Steinlechner Fabian , Torres Juan P. , Ursin Rupert
Published: May 2019

Hong-Ou-Mandel interference, the fact that identical photons that arrive simultaneously on different input ports of a beam splitter bunch into a common output port, can be used to measure optical delays between different paths. It is generally assumed that great precision in the measurement requires that photons contain many frequencies, i.e., a large bandwidth. Here we challenge this “well-known” assumption and show that the use of two well-separated frequencies embedded in a quantum entangled state (discrete color entanglement) suffices to achieve great precision. We determine optimum working points using a Fisher Information analysis and demonstrate the experimental feasibility of this approach by detecting thermally-induced delays in an optical fiber. These results may significantly facilitate the use of quantum interference for quantum sensing, by avoiding some stringent conditions such as the requirement for large bandwidth signals.
Possible Male Infanticide in Wild Orangutans and a Re-evaluation of Infanticide Risk
Authors: Knott Cheryl D. , Scott Amy M. , O’Connell Caitlin A. , Scott Katherine S. , Laman Timothy G. , Riyandi  , Susanto Tri Wahyu
Published: May 2019

Infanticide as a male reproductive tactic is widespread across mammals, and is particularly prevalent in catarrhine primates. While it has never been observed in wild orangutans, infanticide by non-sire males has been predicted to occur due to their extremely long inter-birth intervals, semi-solitary social structure, and the presence of female counter-tactics to infanticide. Here, we report on the disappearance of a healthy four-month-old infant, along with a serious foot injury suffered by the primiparous mother. No other cases of infant mortality have been observed at this site in 30 years of study. Using photographic measurements of the injury, and information on the behavior and bite size of potential predators, we evaluate the possible causes of this injury. The context, including the behavior of the female and the presence of a new male at the time of the injury, lead us to conclude that the most likely cause of the infant loss and maternal injury was male infanticide. We suggest that in orangutans, and other species where nulliparous females are not preferred mates, these females may be less successful at using paternity confusion as an infanticide avoidance tactic, thus increasing the likelihood of infanticide of their first-born infants.
Bifurcation and Pattern Symmetry Selection in Reaction-Diffusion Systems with Kinetic Anisotropy
Authors: Gao Yipeng , Zhang Yongfeng , Schwen Daniel , Jiang Chao , Gan Jian
Published: May 2019

Ordering and self-organization are critical in determining the dynamics of reaction-diffusion systems. Here we show a unique pattern formation mechanism, dictated by the coupling of thermodynamic instability and kinetic anisotropy. Intrinsically different from the physical origin of Turing instability and patterning, the ordered patterns we obtained are caused by the interplay of the instability from uphill diffusion, the symmetry breaking from anisotropic diffusion, and the reactions. To understand the formation of the void/gas bubble superlattices in crystals under irradiation, we establish a general theoretical framework to predict the symmetry selection of superlattice structures associated with anisotropic diffusion. Through analytical study and phase field simulations, we found that the symmetry of a superlattice is determined by the coupling of diffusion anisotropy and the reaction rate, which indicates a new type of bifurcation phenomenon. Our discovery suggests a means for designing target experiments to tailor different microstructural patterns.
Highly stretchable graphene nanoribbon springs by programmable nanowire lithography
Authors: Liu Chuan , Yao Bing , Dong Taige , Ma Haiguang , Zhang Shaobo , Wang Junzhuan , Xu Jun , Shi Yi , Chen Kunji , Gao Libo , Yu Linwei
Published: May 2019

Graphene nanoribbons are ideal candidates to serve as highly conductive, flexible, and transparent interconnections, or the active channels for nanoelectronics. However, patterning narrow graphene nanoribbons to <100 nm wide usually requires inefficient micro/nano fabrication processes, which are hard to implement for large area or flexible electronic and sensory applications. Here, we develop a precise and scalable nanowire lithography technology that enables reliable batch manufacturing of ultra-long graphene nanoribbon arrays with programmable geometry and narrow width down to ~50 nm. The orderly graphene nanoribbons are patterned out of few-layer graphene sheets by using ultra-long silicon nanowires as masks, which are produced via in-plane solid–liquid–solid guided growth and then transferred reliably onto various stiff or flexible substrates. More importantly, the geometry of the graphene nanoribbons can be predesigned and engineered into elastic two-dimensional springs to achieve outstanding stretchability of >30%, while carrying stable and repeatable electronic transport. We suggest that this convenient scalable nanowire lithography technology has great potential to establish a general and efficient strategy to batch-pattern or integrate various two-dimensional materials as active channels and interconnections for emerging flexible electronic applications.
Formation and interconversion of CCN and CNC radicals resulting from the radiation-induced decomposition of acetonitrile in solid noble gas matrices
Authors: Volosatova Anastasia D. , Kameneva Svetlana V. , Feldman Vladimir I.
Published: May 2019

Deep radiolysis of CH3CN in noble gas matrices results in the formation of CCN and CNC radicals, which undergo reversible interconversion under visible/UV photolysis.
Tuning of the flexibility in metal–organic frameworks based on pendant arm macrocycles
Authors: Jeoung Sungeun , Lee Songho , Lee Jae Hwa , Lee Soochan , Choe Wonyoung , Moon Dohyun , Moon Hoi Ri
Published: May 2019

An isostructural series of flexible MOFs based on pendant arm macrocycles was developed to tune flexibility depending on functional groups.
Multicatalytic dearomatization of phenols into epoxyquinols via a photooxygenation process
Authors: Péault Louis , Nun Pierrick , Le Grognec Erwan , Coeffard Vincent
Published: May 2019

An unprecedented synthesis of epoxyquinols bearing three contiguous stereocenters through photooxygenation of para-substituted phenols was developed.
‘Cathodic’ electrochemiluminescence of [Ru(bpy)3]2+ and tri-n-propylamine confirmed as emission at the counter electrode
Authors: Theakstone Ashton G. , Doeven Egan H. , Conlan Xavier A. , Dennany Lynn , Francis Paul S.
Published: May 2019

Monitoring emission and potentials at both the working and counter electrodes provides new insight into a proposed cathodic electrochemiluminescence system.
An activity-based probe developed by a sequential dehydroalanine formation strategy targets HECT E3 ubiquitin ligases
Authors: Xu Ling , Fan Jian , Wang Yu , Zhang Zhongping , Fu Yao , Li Yi-Ming , Shi Jing
Published: May 2019

We developed a novel dehydroalanine-based E2-Ub ABP using a strategy that is combination of practical hydrazide-based native chemical ligation and sequential Dha formation.
Giant enhancement of electronic polarizability and the first hyperpolarizability of fluoride-decorated graphene versus graphyne and graphdiyne: insights from ab initio calculations
Authors: Li Xiaojun , Lu Jun
Published: May 2019

An effective strategy based on the adsorption of alkali-metal fluorides on graphene, graphyne, and graphdiyne is presented for exploring the strong electro-optical properties, which are correlated with the TDDFT two-level model.
Micromechanical simulation of the pore size effect on the structural stability of brittle porous materials with bicontinuous morphology
Authors: Deng Shengwei , Wang Yinbin , Zhuang Guilin , Zhong Xing , Wei Zhongzhe , Yao Zihao , Wang Jian-guo
Published: May 2019

A part of the solid phase in bicontinuous structures sustains the deformation and larger pore sizes result in lower Young's moduli.
Dynamics and reaction kinetics of coarse-grained bulk vitrimers: a molecular dynamics study
Authors: Wu Jian-Bo , Li Shu-Jia , Liu Hong , Qian Hu-Jun , Lu Zhong-Yuan
Published: May 2019

We used the hybrid molecular dynamics–Monte Carlo (MD–MC) algorithm to establish a molecular dynamics model that can accurately reflect bond exchange reactions, and reveal the intrinsic mechanism of the dynamic behavior of the vitrimer system.
Reversible addition and hydrogenation of 1,1-diphenylethylene with a barium complex
Authors: Shi Xianghui , Cheng Jianhua
Published: May 2019

A reversible equilibrium exists between the insertion of one DPE unit and two DPE units into [(TpAd,iPr)Ba(μ-H)]2.
Effects of divalent metal cations and inorganic anions on the transport of tetracycline in saturated porous media: column experiments and numerical simulations
Authors: Li Wenwen , Zhang Haojing , Lu Taotao , Li Yanxiang , Song Yumeng , Shang Zhongbo , Liu Shanhu , Li Deliang , Qi Zhichong
Published: May 2019

Tetracycline is one of the most commonly used antibiotics in the world.
Acquisition of cancer stem cell-like properties in human small airway epithelial cells after a long-term exposure to carbon nanomaterials
Authors: Kiratipaiboon Chayanin , Stueckle Todd A. , Ghosh Rajib , Rojanasakul Liying W. , Chen Yi Charlie , Dinu Cerasela Zoica , Rojanasakul Yon
Published: May 2019

Carbon nanomaterials and asbestos fibers induce genotoxicity and cancer stem cell-like transformation in human small airway epithelial cells.
Enhanced Cr(vi) immobilization on goethite derived from an extremely acidic environment
Authors: Wang Xiaobing , Chen Na , Zhang Lizhi
Published: May 2019

Iron (hydr)oxides play an indispensable role in the immobilization of heavy metal ions in environmental geochemical processes.
Sinapine reduces non-alcoholic fatty liver disease in mice by modulating the composition of the gut microbiota
Authors: Li Youdong , Li Jinwei , Su Qingfeng , Liu Yuanfa
Published: May 2019

Non-alcoholic fatty liver disease (NAFLD) is associated with low-grade chronic inflammation and intestinal dysbiosis.
Evaluation of calcium-, carbon- and sulfur-based non-spectral interferences in high-power MIP-OES: comparison with ICP-OES
Authors: Serrano Raquel , Grindlay Guillermo , Gras Luis , Mora Juan
Published: May 2019

Common matrix-based non-spectral interferences are studied for the first time in high-power MIP-OES. The results are compared with those in ICP-OES.
Synthetic studies on the reverse antibiotic natural products, the nybomycins
Authors: Bardell-Cox Oliver A. , White Andrew J. P. , Aragón Luis , Fuchter Matthew J.
Published: May 2019

We report a new scalable and robust synthetic route to the nybomycin natural products and the activity of novel analogues of this family.
Lanthanum chloride induces neuron damage by activating the nuclear factor-kappa B signaling pathway in activated microglia
Authors: Yan Licheng , Yang Jinghua , Yu Miao , Lu Yanxin , Huang Liling , Wang Jing , Lu Xiaobo , Jin Cuihong , Wu Shengwen , Cai Yuan
Published: May 2019

Lanthanum is a rare earth element which can have adverse effects on the central nervous system (CNS). However, the mechanisms of these effects are not fully understood. The activated microglia plays an important role in the pathogenesis of neurodegenerative diseases and thus could be involved in mediating the toxic effects of lanthanum on the CNS. Nuclear factor-kappa B (NF-κB) is a critical nuclear factor which regulates the expression of inflammatory mediators in the activated microglia. This study investigated the effects of lanthanum chloride (LaCl3) on the NF-κB signaling pathway and explored the relationship between the microglia activation and neuron damage induced by La in vitro. The results showed that BV2 microglial cells treated with 0, 0.05, 0.1 or 0.2 mM LaCl3 could up-regulate the expression of Iba1 protein, a marker of microglia activation, and of p-IKKαβ and p-IκBα in a dose-dependent manner. La could also increase the translocation of the NF-κB p65 subunit from the cytosol into the nucleus, and then elevate the production of NO, TNF-α, IL-1β, IL-6 and MCP-1 by BV2 microglial cells. In a neuron–microglia co-culture system, BV2 microglia treated with LaCl3 resulted in a significant increase of the rates of neuron apoptosis. Conversely, the pre-treatment with PDTC (an inhibitor of the NF-κB signaling pathway) could inhibit the release of inflammatory cytokines and reduce the number of apoptotic neurons caused by La. These findings suggested that the neuron injury induced by LaCl3 might be related to the abnormal activation of microglia, which could remarkably increase the expression and release of pro-inflammatory cytokines via activating the NF-κB signaling pathway.
Mechanistic insight into the formation of colloidal WS2 nanoflakes in hot alkylamine media
Authors: Scarfiello Riccardo , Cesari Andrea , Altamura Davide , Masi Sofia , Nobile Concetta , Balzano Federica , Giannini Cinzia , Grillo Vincenzo , Tavabi Amir H. , Dunin-Borkowski Rafal E. , Uccello-Barretta Gloria , Cozzoli P. Davide , Rizzo Aurora
Published: May 2019

Non-hydrolytic synthesis assisted by long-chain amphiphilic surfactant is exploited to generate dimension-controllable 2D-WS2 nanoflakes in a single-step protocol, where the chemical nature and steric hindrance of the alkylamine are the key points to modulate the lateral size finally achieved.
Copper-mediated anomeric O-arylation with organoboron reagents
Authors: Dimakos Victoria , Liu Jacklyn J. W. , Ge Zhenlu , Taylor Mark S.
Published: May 2019

Copper-mediated couplings of boroxines with glycosyl hemiacetals generate O-aryl glycosides via Csp2–O bond formation.
Visible-light mediated sulfonylation of thiols via insertion of sulfur dioxide
Authors: Nair Akshay M. , Kumar Shreemoyee , Halder Indranil , Volla Chandra M. R.
Published: May 2019

Photocatalytically generated sulfenyl radicals were coupled with arylsulfonyl radicals at room temperature for accessing unsymmetrical organic thiosulfonates.
AIEgen functionalized inorganic–organic hybrid nanomaterials for cancer diagnosis and therapy
Authors: Li Dongdong
Published: May 2019

AIEgen functionalized inorganic–organic hybrid nanomaterials with multifunctions can be used for cancer diagnosis and imaging-guided synergistic therapy.
Tuneable access to isoquinolines via a transition-metal-free C(sp3)–C(sp3) bond cleavage rearrangement reaction
Authors: Wang Jian , Cai Panyuan , He Yimiao , Liu Yuan , Zhong Ling , Ding Shumin , Shang Yongjia
Published: May 2019

A novel divergent synthesis of multi-substituted isoquinolines via C(sp3)–C(sp3) bond cleavage rearrangement reactions was realized.
Catalyst- and additive-free annulation/aromatization leading to benzothiazoles and naphthothiazoles
Authors: Xu Zhenhua , Huang Huawen , Chen Hongbiao , Deng Guo-Jun
Published: May 2019

Catalyst- and additive-free three-component annulation/aromatization enable a highly efficient entry to naphtho[1,2-d]thiazoles and benzo[d]thiazoles.
A vinyl silylsilylene and its activation of strong homo- and heteroatomic bonds
Authors: Roy Matthew M. D. , Ferguson Michael J. , McDonald Robert , Zhou Yuqiao , Rivard Eric
Published: May 2019

A facile route to an two-coordinate acyclic silylene that can activate strong homo- and heteroatomic bonds is reported.
Rhodium-catalysed vinyl 1,4-conjugate addition coupled with Sharpless asymmetric dihydroxylation in the synthesis of the CDE ring fragment of pectenotoxin-4
Authors: Richardson Melodie S. W. , Tame Christopher J. , Poole Darren L. , Donohoe Timothy J.
Published: May 2019

Rhodium and osmium catalysed C–C and C–O bond formation under mild conditions.
Core-crystalline nanoribbons of controlled length via diffusion-limited colloid aggregation
Authors: Schmarsow Ruth N. , Ceolín Marcelo , Zucchi Ileana A. , Schroeder Walter F.
Published: May 2019

The mobility of the medium during crystallization-driven self-assembly plays a crucial role in the elongation process of 1D nanoribbons.
High‐efficiency series–parallel form hybrid envelope‐tracking power supply based on the optimised power losses
Authors: Pan Yong , He Songbai , Tang Xiaobin
Published: May 2019

To achieve high efficiency, an optimised method of the series–parallel form (SPF) hybrid envelope tracking power supply based on hysteresis current control is proposed in this Letter. The SPF hybrid power modulator is constituted by one linear regulator and two switched‐mode converters which include one multilevel converter and one buck converter. Based upon the equivalent average current slew rate matching theory and accurate power loss model analysed in this Letter, the voltage distribution of the multilevel converter is optimised. For verification, a prototype is fabricated aiming for tracking the 10‐MHz LTE envelope signal with the efficiency of 83%, 26.9 W average output power, and 67.6 W maximum output power.
Review based on losses, torque ripple, vibration and noise in switched reluctance motor
Authors: Seshadri Arjun , Lenin Natesan Chokkalingam
Published: May 2019

Some key features to be satisfied by electric motors catering a wide range of applications are high specific power, lower manufacturing cost, rugged construction, and fault‐tolerant operation. Switched reluctance motor is one such motor technology satisfying all the above requirements and is an emerging competitor to the induction and permanent magnet motors in domestic, industrial and electric vehicle applications. The present‐day research on this motor is moving towards improving efficiency at lower speeds, power density, and the torque density. Certain challenges in achieving the same are (a) minimising the losses, (b) mitigation of torque ripple, noise, and vibration, and (c) material advancements. A review based on the estimation and mitigation techniques of each of these over the past three to four decades has been dealt with in this study. The salient features and results in each section provide a clear understanding of how each of these challenges can be overcome in the aspect of design and control strategies.
Optimisation of MG operation considering effects of power electronic converters
Authors: Ebrahimi Anooshirvan , Fathi S. Hamid
Published: May 2019

A prominent issue in microgrid (MG) cost optimisation is the consideration of variable parameters such as demand, wind speed, sun radiation intensity etc. This study deals with mitigating substantial deviation between study results and actual MG operation indices. The deviation is the result of ignoring the effects of power electronics devices in the optimisation algorithm. A new optimisation model is proposed to involve the main converter's restrictions in the optimisation process. For connecting renewable sources with uncertain outputs such as photovoltaic, wind, and also loads to a MG, using power electronic converters is inevitable. This study proposes an operation cost optimisation development by foreseeing the effects and limitations of power electronic devices, disregarding of which would undoubtedly lead to a notable deviation in optimisation results.
ULX contribution to stellar feedback: an intermediate-mass black hole candidate and the population of ULXs in the low-metallicity starburst galaxy ESO 338-4
Authors: Oskinova L. M. , Bik A. , Mas-Hesse J. M. , Hayes M. , Adamo A. , Östlin G. , Fürst F. , Otí-Floranes H.
Published: May 2019

Context. X-ray radiation from accreting compact objects is an important part of stellar feedback. The metal-poor galaxy ESO 338-4 has experienced vigorous starburst during the last <40 Myr and contains some of the most massive super star clusters in the nearby Universe. Given its starburst age and its star-formation rate, ESO 338-4 is one of the most efficient nearby manufactures of neutron stars and black holes, hence providing an excellent laboratory for feedback studies.

Aims. We aim to use X-ray observations with the largest modern X-ray telescopes XMM-Newton and Chandra to unveil the most luminous accreting neutron stars and black holes in ESO 338-4.

Methods. We compared X-ray images and spectra with integral field spectroscopic observations in the optical to constrain the nature of strong X-ray emitters.

Results. X-ray observations uncover three ultraluminous X-ray sources (ULXs) in ESO 338-4. The brightest among them, ESO 338 X-1, has X-ray luminosity in excess of 1040 erg s−1. We speculate that ESO 338-4 X-1 is powered by accretion on an intermediate-mass (≳300 M⊙) black hole. We show that X-ray radiation from ULXs and hot superbubbles strongly contributes to He II ionization and general stellar feedback in this template starburst galaxy.
Application of roller burnishing technologies to improve the wear resistance of submerged pump parts made of powder alloys
Authors: Kropotkina Elena , Zykova Marina , Shein Alexander , Kapustina Natalya
Published: May 2019

This paper presents experimental studies of the influence of surface plastic deformation (SPD) (roller burnishing) on the properties of the surface layer of a part “guide apparatus” of the centrifugal submersible pump for oil production. The parts made of composite powder alloys based on the iron-copper system were taken as an object of researches. The microstructure of the surface layer of the samples, surface roughness, microhardness, and hardness were studied. Testing of the samples for the surface layer resistance to abrasive wear according to the Calotest method showed a decrease in the wear intensity by 1.5–1.6 times in comparison to samples without SPD.
Lubricant-free deep drawing using CO2 and N2 as volatile media injected through laser-drilled microholes
Authors: Zahedi Ehsan , Woerz Christoph , Reichardt Gerd , Umlauf Georg , Liewald Mathias , Barz Jakob , Weber Rudolf , Foerster Daniel J. , Graf Thomas
Published: May 2019

Most metal forming processes use lubricants based on mineral oils as an intermediate medium to reduce friction and wear. To avoid the well-known drawbacks of oil lubrication, a novel and environment friendly lubrication system for deep-drawing processes was demonstrated at the University of Stuttgart. Liquid carbon dioxide and gaseous nitrogen are being used as volatile lubrication during the deep-drawing process, locally injected at high pressure through laser-drilled microholes. This new tribological system provides a significantly enlarged working range and at least 15% larger drawing depths compared to conventional oil lubrication.
Genetic profiling in der Diagnostik des hereditären Prostatakarzinoms – wo stehen wir?
Authors: Thomas Christian , Tsaur Igor , Boehm Katharina
Published: May 2019

Prostatakrebs weist im Vergleich zu anderen Tumorentitäten ein heterogenes genetisches Profil auf. Dementsprechend sind auch Mutationen, die das Prostatakarzinomrisiko erhöhen, vielfältig. Manche genetische Varianten fallen bei der Risikoerhöhung nur milde ins Gewicht. Andere Genmutationen (BRCA1/2; HOXB13) erhöhen das Risiko jedoch teils erheblich. Insgesamt ist die Wahrscheinlichkeit für einen nicht familiär vorbelasteten Mann, ein Träger von Mutationen zu sein, welche mit einem erhöhten PCa-Risiko assoziiert sind, niedrig. Ist aber die familiäre Belastung durch in jungem Alter erkrankte Verwandte oder eine bereits bekannte Mutation in der Familie vorhanden, so steigt auch diese Wahrscheinlichkeit an. In diesen Fällen sollte die genetische Beratung und Testung in Betracht gezogen werden. Insbesondere soll hier an BRCA1/2-Mutationen und HOXB13-Mutationen gedacht werden. Für die breite Bevölkerungsmasse kann genetic profiling bislang jedoch nicht die PSA-Wert-Bestimmung, mpMRT der Prostata und/oder die Prostatabiopsie im Rahmen der Vorsorge oder des diagnostischen Algorithmus ersetzen. Lediglich können Männer bei Vorliegen der mit PCa assoziierten Mutationen einem engmaschigeren und früheren Screening unterzogen werden und ggf. früher eine definitive Therapie erhalten.
Absolute quasi-static calibration method of piezoelectric high-pressure sensor based on force sensor
Authors: Gu Tingwei , Shang Fei , Kong Deren , Xu Chundong
Published: May 2019

In this paper, a strain-gauge-type force sensor which can be directly mounted on the existing drop-weight device and used to calibrate the piezoelectric high-pressure sensor is designed. The absolute quasistatic pressure calibration principle and the measurement principle of the strain-gauge-type force sensor are described. Based on the mathematical relation model between force and pressure, the influence factors of pressure calibration accuracy are discussed, and the empirical formula for correcting the peak pressure is obtained. To analyze the mechanical strength of the force sensor, the modal parameters of the force sensor in the impact direction, and the pressure loss in the transmission process, a finite element simulation based on ANSYS software is performed. In addition, the static characteristic of the force sensor and the dynamic characteristic of the new drop-weight system composed of the force sensor, the mounting frame, and weight stacks are analyzed. To verify the accuracy of the empirical formula, the absolute quasistatic pressure calibration experiment is performed based on the calibration device. The final experimental results show that the accuracy of pressure calibration can be effectively improved by means of empirical formula correction. Taking the peak pressure measured by the reference pressure sensors as the standard value, the maximum calculation difference can be reduced from 3.42% (obtained by the direct calculation method) to 0.70% by the empirical formula correction method.
Mechanical model analysis for resonance shear measurement
Authors: Mizukami Masashi , Hemette Sylvain , Kurihara Kazue
Published: May 2019

Resonance shear measurement (RSM), which we developed based on a surface force apparatus, can investigate the structuring, and rheological and tribological properties of confined liquids as a function of the surface separation distance (D) from several μm to zero with a nanometer resolution. Using RSM, we reported that the nanoconfined liquids, including commercial lubricants, exhibited properties quite different from the bulk phase. Mechanical modeling of the resonance system is necessary to quantitatively evaluate the properties of confined liquids and/or sheared interfaces. In this study, we improved the model for RSM as follows: (1) We directly measured the movements of the upper and lower surfaces in addition to the measurement on the movement of the vertical spring to confirm the model, which could be used to estimate the parameters used in the model; (2) we proposed a modified mechanical model which considers the effect of additional motion. This model could fit the resonance curves using a identical apparatus constant for the entire measurement range, while the characteristic values of the confined liquids are the same as those obtained using our previous model, and (3) we calculated the friction (shear) force using the improved model and obtained the characteristic values (viscous and elastic parameters) of the confined liquids. This study afforded the simplicity and reliability of a mechanical model analysis of resonance curves, and the friction force calculation employing the viscous and elastic terms can be useful for studying the mechanism of friction force.
Mean field theory of thermal energy transport in molecular junctions
Authors: Kelly Aaron
Published: May 2019

Mean field theory is applied to nonequilibrium thermal energy transport in a model molecular junction. An approximation to the total time-dependent heat current in the junction is constructed using an ensemble of Ehrenfest trajectories, and the average heat current in the steady state is obtained. The accuracy of this treatment is verified through benchmark comparisons with exact quantum mechanical results and various approximate quantum transport theories for the nonequilibrium spin-boson model. The performance of the multitrajectory Ehrenfest approach is found to be quite robust, displaying good accuracy in intermediate cases that remain elusive to many perturbative approximations and in the strong coupling limit where many methods break down. Thus, mean field theory and related trajectory-based approximate quantum dynamics methods emerge as a promising toolkit for the study of transport properties in nanoscale systems.
An integrated laser system for the cold atom clock
Authors: Yu Mingyuan , Cheng Huadong , Meng Yanling , Wan Jinyin , Wang Xin , Ouyang Xinchuan , Xiao Ling , Liu Liang
Published: May 2019

We demonstrate an integrated laser system for the mobile integrating sphere cold atom clock. Three distributed Bragg reflector diode lasers (780 nm) with custom drive circuits are used for the cooling, repumping, pumping, and probe lights. Automatic frequency-locking and relocking of the laser are presented. All of the optical elements are integrated on two sides of an aluminum base plate. The mechanical structure is simulated and optimized to minimize the deformation of the base plate. We optimize, measure, and discuss the frequency and intensity noises of the laser system. The techniques and designs used in this laser system can also be used in other mobile platforms for quantum sensing experiments.
Three-dimensional modeling and hydrodynamic scaling of National Ignition Facility implosions
Authors: Clark D. S. , Weber C. R. , Milovich J. L. , Pak A. E. , Casey D. T. , Hammel B. A. , Ho D. D. , Jones O. S. , Koning J. M. , Kritcher A. L. , Marinak M. M. , Masse L. P. , Munro D. H. , Patel M. V. , Patel P. K. , Robey H. F. , Schroeder C. R. , Sepke S. M. , Edwards M. J.
Published: May 2019

The goal of an inertially confined, igniting plasma on the National Ignition Facility (NIF) [M. L. Spaeth, Fusion Sci. Technol. 69, 25 (2016)] remains elusive. However, there is a growing understanding of the factors that appear to be limiting current implosion performance. And with this understanding, the question naturally arises: What conditions will ultimately be required to achieve ignition, either by continuing to improve the quality of current implosions, or by hydrodynamically scaling those implosions to larger driver energies on some future facility? Given the complexity of NIF implosions, answering this question must rely heavily on sophisticated numerical simulations. In particular, those simulations must respect the three-dimensionality of real NIF implosions and also resolve the wide range of scales for the many perturbation sources that degrade them. This prospectus article reviews the current state of detailed modeling of NIF implosions, the scaling to ignition from recent experiments that that modeling implies, and areas for future improvements in modeling technique that could increase understanding and further enhance predictive capabilities. Given the uncertainties inherent in any extrapolation, particularly for a process as nonlinear as ignition, there will be no definitive answer on the requirements for ignition until it is actually demonstrated experimentally. However, with continuing improvements in modeling technique and a growing experience base from NIF, the requirements for ignition are becoming clearer.
Extension of the neutron scatter camera sensitivity to the ∼10–200 MeV neutron energy range
Authors: Cabrera Palmer B. , Brubaker E. , Gerling M. , Reyna D.
Published: May 2019

The Neutron Scatter Camera (NSC) is a neutron spectrometer and imager that has been developed and improved by the Sandia National Laboratories for several years. Built for special nuclear material searches, the instrument was configured by the design to reconstruct neutron sources within the fission energy range 1–10 MeV. In this work, we present modifications that attempt to extend the NSC sensitivity to neutron energies in the range ∼10–200 MeV and discuss the corresponding consequences for the event processing. We present simulation results that manifest important aspects of the NSC response to those intermediate energy neutrons. The simulation results also evidence that the instrument’s spectroscopic capabilities severely deteriorate at those energies, mainly due to the uncertainties in measuring energy, time, and distance between the two neutron scattering interactions. This work is motivated by the need to characterize neutron fluxes at particle accelerators as they may represent important backgrounds for neutrino experiments.
The extended explicitly-correlated second-order approximate coupled-cluster singles and doubles ansatz suitable for response theory
Authors: Höfener Sebastian , Schieschke Nils , Klopper Wim , Köhn Andreas
Published: May 2019

We report the extended explicitly correlated approximate coupled-cluster singles and doubles CC2(F12*)-XSP method suitable for response properties. Equations are derived using an automated approach and have subsequently been hand-coded into the computer program KOALA, in which for all two-electron integrals, density fitting is employed. Numerical results are presented for the lowest two vertical singlet excitation energies of a set of selected molecules. The results show that the CC2(F12*)-XSP method provides the correct basis-set limit with no bias to the ground state, and an excellent agreement with reference CC2 values using large basis sets is found. Using Dunning’s aug-cc-pVTZ basis, the CC2(F12*)-XSP method yields excitation energies which are converged within 1 mEh to the basis-set limit for valence excitations.
Multiple short pulse process for low-temperature atomic layer deposition and its transient steric hindrance
Authors: Wang Haoran , Wang Zhenyu , Xu Xiangchen , Liu Yunfei , Chen Chen , Chen Ping , Hu Wei , Duan Yu
Published: May 2019

Low-temperature atomic layer deposition (ALD) is increasingly used in the field of organic optoelectronics. However, the deposition of ALD outside the temperature window still cannot be stably implemented. In this study, transient steric hindrance caused by gas-phase molecules at low-temperature (80 °C and 30 °C) was investigated. In order to mitigate the effect of this transient hindrance, a process of consecutive short-pulses was adopted in our experiments. As a result, the density of Alucone films increased from 2.21 g/cm3 to 2.37 g/cm3 and the density of room-temperature deposited Al2O3 films increased 28.6% from 2.41 g/cm3 to 3.1 g/cm3. Overall, the proposed idea would help low-temperature ALD become mature and be widely promoted.
High field-emission current density from β-Ga2O3 nanopillars
Authors: Grillo Alessandro , Barrat Julien , Galazka Zbigniew , Passacantando Maurizio , Giubileo Filippo , Iemmo Laura , Luongo Giuseppe , Urban Francesca , Dubourdieu Catherine , Di Bartolomeo Antonio
Published: May 2019

Field emission from gallium oxide (β-Ga2O3) nanopillars, etched by Ne+ ion milling on β-polymorph (100) single crystals, is reported. A stable field emission current, with a record density over 100 A/cm2 and a turn on field of ∼ 30 V/μm, is achieved. We expect that the high field enhancement factor of about 200 at a cathode-anode distance of 1 μm can be further increased by optimizing the shape of the nanopillar apex. This work demonstrates that the material properties combined with an appropriate nano-patterning can make β-Ga2O3 competitive or better than other well-established field emitters.
Phosphorene-based van der Waals heterojunction for solar water splitting
Authors: Wang Peng , Meng Jie , Huang Jing , Wang Jia-jun , Li Qun-xiang
Published: May 2019

As a clean and renewable future energy source, hydrogen fuel can be produced via solar water splitting. Two-dimensional (2D) black phosphorene (black-P) can harvest visible light due to the desirable band gap, which promises it as a metal-free photocatalyst. However, black-P can be only used to produce hydrogen since the oxidation potential of water locates lower than the position of the valence band maximum. To improve the photocatalytic performance of black-P, here, using black-P and blue phosphorene (blue-P) monolayers, we propose a 2D van der Waals (vdW) heterojunction. Theoretical results, including the band structures, density of states, Bader charge population, charge density difference, and optical absorption spectra, clearly reveal that the visible light absorption ability is obviously improved, and the band edge alignment of the proposed vdW heterojunction displays a typical type-II feature to effectively separate the photogenerated carriers. At the same time, the built-in interfacial electric field prevents the electron-hole recombination. These predictions suggest that the examined phosphorene-based vdW heterojunction is an efficient photocatalyst for solar water splitting.