bluuebunny/crossref_metadata_2025 huggingface dataset:
MESSENGER Observations and Global Simulations of Highly Compressed Magnetosphere Events at Mercury
Authors: Jia Xianzhe , Slavin James A. , Poh Gangkai , DiBraccio Gina A. , Toth Gabor , Chen Yuxi , Raines Jim M. , Gombosi Tamas I.
Published: January 2019

We identify and examine all MErcury Surface Space ENvironment, GEochemistry, and Ranging (MESSENGER) crossings of Mercury's dayside magnetopause with magnetospheric field intensities ≥300 nT. The eight such events, which occurred under highly compressed magnetosphere conditions, are analyzed in the identical manner utilized by Slavin et al. (2014, https://doi.org/10.1002/2014JA020319). The results suggest that the eight highly compressed magnetosphere events represent the highest solar wind dynamic pressures for which the MESSENGER's orbit still passed below the magnetopause and provided measurements of the dayside magnetosphere. Using the magnetohydrodynamic model by Jia et al. (2015, https://doi.org/10.1002/2015JA021143) that electromagnetically couples Mercury's interior with its magnetosphere, a series of global simulations are conducted to quantitatively characterize the response of Mercury's magnetosphere to solar wind forcing. Combining the MESSENGER observations with the simulations, we have obtained a consistent picture of how Mercury's dayside magnetospheric configuration is controlled, separately and in combination, by induction‐driven shielding and reconnection‐driven erosion. For solar wind pressures of ∼40–90 nPa, compared with the average ∼10–15 nPa at Mercury's orbit, the shielding effects of induction in Mercury's core in standing‐off the solar wind typically exceed the erosion of the dayside magnetosphere due to reconnection for these events, most of which occurred under low magnetic shear conditions. For high magnetic shear across the magnetopause our simulation predicts that reconnection would dominate. Mercury's effective magnetic moment as inferred from magnetopause standoff distance ranges from 170 to 250 
for these events. These findings are of crucial importance for understanding the space weathering at Mercury and its contribution to the generation of Mercury's exosphere.
Improvement of a Deep Learning Algorithm for Total Electron Content Maps: Image Completion
Authors: Chen Zhou , Jin Mingwu , Deng Yue , Wang Jing‐Song , Huang Heng , Deng Xiaohua , Huang Chun‐Ming
Published: January 2019

Observations with a global coverage are very important for space physics research and space weather monitoring. However, due to the technical limitations, it would be very expensive or even impossible to achieve a seamless global coverage even with advanced observational devices. It would be useful to fill missing data gaps to create a global map from the available data, but up until now this has been very challenging. Fortunately, the deep learning method, a recent breakthrough in artificial intelligence, may provide an effective way to solve this problem by making full use of data from reliable observations. In this paper, a promising deep learning algorithm, deep convolutional generative adversarial network (DCGAN), is investigated to fill the missing data of total electron content (TEC) map images. The direct use of DCGAN fails to fill missing data for the completion of TEC maps because there are always missing TEC data in some regions, such as oceans, where the features vary with time and geophysical conditions. Thus, no useful information can be utilized by DCGAN to achieve a meaningful image completion. In order to overcome this shortcoming of the original DCGAN method, a novel regularized DCGAN (R‐DCGAN) is proposed by adding an extra discriminator and some widely used reference TEC maps from the International Global Navigation Satellite Systems Service Ionosphere Working Group. The proposed R‐DCGAN method generates satisfactory ionospheric peak structures at different times and geomagnetic conditions, which demonstrate its effectiveness on filling the missing data in TEC maps. The proposed R‐DCGAN framework can be readily extended to a broad application in other fields of space sciences, particularly for addressing the missing observation data issues.
Seismoacoustic Analysis of Chemical Explosions at the Nevada National Security Site
Authors: Pasyanos Michael E. , Kim Keehoon
Published: January 2019

In recent years, two sets of chemical explosions have been conducted at the Nevada National Security Site: six explosions from Phase I of the Source Physics Experiment and four explosions from the Forensics Surface Events. We have estimated the explosive yield and depth‐of‐burial/height‐of‐burst of both from the synthesis of seismic and low‐frequency acoustic data. Analysis of the seismic signal is performed using a waveform envelope technique. Using seismic data only, however, there is a trade‐off between the yield and depth or height of the explosion, which becomes especially acute for near‐surface events. This trade‐off between yield and depth/height can be broken by including complementary analysis of the acoustic signal using the acoustic waveform inversion method. The acoustic signal also has a strong trade‐off between a yield and depth/height, but the slope is opposite that of the seismic for near‐surface events. We use a likelihood function to combine the seismic and acoustic analysis and improve our estimates of yield and depth/height for these sets of explosions. The results are generally consistent with the known parameters, but can be improved upon by higher‐frequency seismic analysis and improved acoustic impulse scaling for large‐scaled depths‐of‐burial. These events serve as prime examples of data fusion from multiple data streams. The challenge will be to apply the method to events at longer regional distances where the seismic signals will include phases traveling in the upper mantle, and the acoustic signals will be recorded as infrasound signals, which are subject to atmospheric variability.
The Generation and Scaling of Longitudinal River Profiles
Authors: Roberts Gareth G. , White Nicky , Lodhia Bhavik Harish
Published: January 2019

The apparent success of inverse modeling of continent‐wide drainage inventories is perplexing. An ability to obtain reasonable fits between observed and calculated longitudinal river profiles implies that drainage networks behave simply and predictably at length scales of O(102–103) km and time scales of O(100–102) Ma. This behavior suggests that rivers respond in an organized way to large‐scale tectonic forcing. On the other hand, stream power laws are empirical approximations since fluvial processes are complex, nonlinear, and probably susceptible to disparate temporal and spatial shocks. To bridge the gap between these different perceptions of landscape evolution, we present and interpret a suite of power spectra for African river profiles that traverse different climatic zones, lithologic boundaries, and biotic distributions. At wavelengths
102 km, power spectra have slopes of −2, consistent with red noise, demonstrating that profiles are self‐similar at these length scales. At wavelengths
102 km, there is a crossover transition to slopes of −1, consistent with pink noise, for which power scales according to the inverse of wavenumber. Onset of this transition suggests that spatially correlated noise, perhaps generated by instabilities in water flow and by lithologic heterogeneities, becomes more prevalent at wavelengths shorter than ∼100 km. At longer wavelengths, this noise gradually diminishes and self‐similar scaling emerges. Our analysis is consistent with the concept that complexities of river profile development can be characterized by an adaptation of the Langevin equation, by which simple advective models of erosion are driven by a combination of external forcing and noise.
Physical Conditions of Fast Glacier Flow: 3. Seasonally‐Evolving Ice Deformation on Store Glacier, West Greenland
Authors: Young T. J. , Christoffersen P. , Doyle S. H. , Nicholls K. W. , Stewart C. L. , Hubbard B. , Hubbard A. , Lok L. B. , Brennan P. V. , Benn D. I. , Luckman A. , Bougamont M.
Published: January 2019

Temporal variations in ice sheet flow directly impact the internal structure within ice sheets through englacial deformation. Large‐scale changes in the vertical stratigraphy within ice sheets have been previously conducted on centennial to millennial timescales; however, intra‐annual changes in the morphology of internal layers have yet to be explored. Over a period of 2 years, we use autonomous phase‐sensitive radio‐echo sounding to track the daily displacement of internal layers on Store Glacier, West Greenland, to millimeter accuracy. At a site located ∼30 km from the calving terminus, where the ice is ∼600 m thick and flows at ∼700 m/a, we measure distinct seasonal variations in vertical velocities and vertical strain rates over a 2‐year period. Prior to the melt season (March–June), we observe increasingly nonlinear englacial deformation with negative vertical strain rates (i.e., strain thinning) in the upper half of the ice column of approximately −0.03 a−1, whereas the ice below thickens under vertical strain reaching up to +0.16 a−1. Early in the melt season (June–July), vertical thinning gradually ceases as the glacier increasingly thickens. During late summer to midwinter (August–February), vertical thickening occurs linearly throughout the entire ice column, with strain rates averaging 0.016 a−1. We show that these complex variations are unrelated to topographic setting and localized basal slip and hypothesize that this seasonality is driven by far‐field perturbations in the glacier's force balance, in this case generated by variations in basal hydrology near the glacier's terminus and propagated tens of kilometers upstream through transient basal lubrication longitudinal coupling.
Comment on “Derivation of a Sigmoid Generalized Complementary Function for Evaporation With Physical Constraints” by S. Han and F. Tian
Authors: Szilagyi Jozsef , Crago Richard D.
Published: January 2019

The sigmoid function Han and Tian derive for their E/Ep = f (Er/Ep) complementary relationship leads to physical contradictions, therefore cannot be accepted as an improvement of existing complementary relationship theory.
Microbes Rain Down from Above, to the Tune of the Seasons
Authors: Duncombe Jenessa
Published: January 2019

Every time snow or rain falls, it brings with it microbes from high in the atmosphere. Could those microbes have a seasonal signal, just like the plants on the land below?
Predicting long-term corrosion of metal alloys in physical infrastructure
Authors: Melchers Robert E.
Published: January 2019

The conditions for initiation and the subsequent development of the severity of corrosion of metal alloys in the short term continue to be of research interest. However, for most physical infrastructure the critical issue often is the development and progression of corrosion under some level of oxygenated conditions, over several decades. In many cases this has significant implications for safety and for economic loss. Increasingly, asset management decision-making requires robust tools or models to predict the effect of corrosion, including loss, pit depth and crevice severity. The present capability in this area is reviewed and available models generally compared, including their degree of empiricism and their relationship to corrosion science fundamentals. It is argued that in addition to the role of material imperfections and corrosion products, the immediate physical environment adjacent to the metal alloy also can play a major role. These aspects are explored and some speculation made about required future research directions.
The Tri-phasic Role of Hydrogen Peroxide in Blood-Brain Barrier Endothelial cells
Authors: Anasooya Shaji Chinchusha , Robinson Bobby D. , Yeager Antonia , Beeram Madhava R. , Davis Matthew L. , Isbell Claire L. , Huang Jason H. , Tharakan Binu
Published: January 2019

Hydrogen peroxide (H2O2) plays an important role physiologically as the second messenger and pathologically as an inducer of oxidative stress in injury, ischemia and other conditions. However, it is unclear how H2O2 influences various cellular functions in health and disease differentially, particularly in the blood-brain barrier (BBB). We hypothesized that the change in cellular concentrations of H2O2 is a major contributor in regulation of angiogenesis, barrier integrity/permeability and cell death/apoptosis in BBB endothelial cells. Rat brain microvascular endothelial cells were exposed to various concentrations of H2O2 (1 nM to 25 mM). BBB tight junction protein (zonula ocludens-1; ZO-1) localization and expression, cytoskeletal organization, monolayer permeability, angiogenesis, cell viability and apoptosis were evaluated. H2O2 at low concentrations (0.001 μM to 1 μM) increased endothelial cell tube formation indicating enhanced angiogenesis. H2O2 at 100 μM and above induced monolayer hyperpermeability significantly (p < 0.05). H2O2 at 10 mM and above decreased cell viability and induced apoptosis (p < 0.05). There was a decrease of ZO-1 tight junction localization with 100 μm H2O2, but had no effect on protein expression. Cytoskeletal disorganizations were observed starting at 1 μm. In conclusion H2O2 influences angiogenesis, permeability, and cell death/apoptosis in a tri-phasic and concentration-dependent manner in microvascular endothelial cells of the blood-brain barrier.
A parallelized molecular collision cross section package with optimized accuracy and efficiency
Authors: Ieritano Christian , Crouse Jeff , Campbell J. Larry , Hopkins W. Scott
Published: January 2019

A new parallelized calculation package predicts collision cross sections with high accuracy and efficiency.
MRI-visible and pH-sensitive micelles loaded with doxorubicin for hepatoma treatment
Authors: Li Bo , Cai Mingyue , Lin Liteng , Sun Weitong , Zhou Zhimei , Wang Shiyin , Wang Yong , Zhu Kangshun , Shuai Xintao
Published: January 2019

A novel pH-sensitive micelle was constructed to efficiently co-deliver SPIONs and doxorubicin for cancer theranostic application.
A twisted macrocyclic hexanuclear palladium complex with internal bulky coordinating ligands
Authors: Nagai Akira , Nakamura Takashi , Nabeshima Tatsuya
Published: January 2019

A macrocyclic hexanuclear palladium complex, which accumulates coordination sites on metals inside the cavity, was found to take a uniquely-twisted conformation when six molecules of a bulky pyridine derivative coordinated to the palladium.
A balancing act of two electrons on a symmetric double-well barrier in a high frequency oscillating field
Authors: Raj Prashant , Pananghat Balanarayan
Published: January 2019

Barrier top stabilization and temporal control of electrons in an oscillating electric field.
Highly localized H2O librational motion as a far-infrared spectroscopic probe for microsolvation of organic molecules
Authors: Mihrin D. , Andersen J. , Jakobsen P. W. , Wugt Larsen R.
Published: January 2019

This work demonstrates how large-amplitude OH librational motion of H2O molecules directly reflects the microsolvation of organic compounds. The highly localized OH librational motion of the first solvating H2O molecule gives rise to a strong band origin νlib in the far-infrared spectral region, which is correlated quantitatively with the intermolecular hydrogen bond energy D0.
Spatial confinement – rapid 2D F−diffusion in micro- and nanocrystalline RbSn2F5
Authors: Gombotz Maria , Lunghammer Sarah , Breuer Stefan , Hanzu Ilie , Preishuber-Pflügl Florian , Wilkening H. Martin R.
Published: January 2019

NMR and conductivity spectroscopy reveal 2D diffusion in both microcrystalline and nanocrystalline RbSn2F5.
Electrophilic boron carboxylate and phosphinate complexes
Authors: Zhu Diya , LaFortune James H. W. , Melen Rebecca L. , Stephan Douglas W.
Published: January 2019

A series of carboxylic acid derivatives of the form [RC(O)OB(C6F5)]2O, (R = Tol, Ph, C6F5, Me2BrC, Me) were prepared with the concurrent reduction to the corresponding aldehyde. The mechanism is proposed to proceed via cyclic eight-membered ring species.
Eco-friendly decarboxylative cyclization in water: practical access to the anti-malarial 4-quinolones
Authors: Ma Yue , Zhu Yongping , Zhang Dong , Meng Yuqing , Tang Tian , Wang Kun , Ma Ji , Wang Jigang , Sun Peng
Published: January 2019

An eco-friendly decaboxylative cyclization in water has been developed to construct 4-quinolones from readily available isatoic anhydrides and 1,3-dicarbonyl compounds.
Non-flammable and moisture-permeable UV protection films only from plant polymers and clay minerals
Authors: Shikinaka Kazuhiro , Nakamura Masaya , Navarro Ronald R. , Otsuka Yuichiro
Published: January 2019

We propose transparent, non-flammable UV protection films consisting of only lignin and clay minerals without petroleum-based hazardous components.
Label-free enrichment of primary human skeletal progenitor cells using deterministic lateral displacement
Authors: Xavier Miguel , Holm Stefan H. , Beech Jason P. , Spencer Daniel , Tegenfeldt Jonas O. , Oreffo Richard O. C. , Morgan Hywel
Published: January 2019

Cell sorting using label-free microfluidic approaches offer significant promise for skeletal stem cell enrichment from human bone marrow.
Microfluidic on-demand droplet generation, storage, retrieval, and merging for single-cell pairing
Authors: Babahosseini Hesam , Misteli Tom , DeVoe Don L.
Published: January 2019

A multifunctional microfluidic platform combining on-demand aqueous-phase droplet generation, multi-droplet storage, and controlled merging of droplets selected from a storage library in a single integrated microfluidic device is described.
Assembly and applications of 3D conformal electronics on curvilinear surfaces
Authors: Huang YongAn , Wu Hao , Xiao Lin , Duan Yongqing , Zhu Hui , Bian Jing , Ye Dong , Yin Zhouping
Published: January 2019

Assembling multifunctional thin devices onto arbitrary curvilinear surfaces allows widespread and innovative applications in artificial intelligence and advanced healthcare industries.
Fast-response ionogel humidity sensor for real-time monitoring of breathing rate
Authors: Xiao Songhua , Nie Jianxia , Tan Rou , Duan Xiaochuan , Ma Jianmin , Li Qiuhong , Wang Taihong
Published: January 2019

Ionogel-based chemoresistive humidity sensors have been successfully fabricated through ionothermal assembly of ionic liquids into a silica network, which exhibited superior humidity performances. Fast substantial impedance changes were observed with changing humidity for real-time monitoring of human breath.
V2(PO4)O/C@CNT hollow spheres with a core–shell structure as a high performance anode material for lithium-ion batteries
Authors: Xiao Bin , Zhang Wen-hai , Xia Hai-feng , Wang Zhi-teng , Tang Lin-bo , An Chang-sheng , He Zhen-jiang , Tong Hui , Zheng Jun-chao
Published: January 2019

V2(PO4)O/C@CNT hollow spheres (HSs) with a core–shell structure were successfully synthesized by a simple spray drying method.
A chemical-bond-driven edge reconstruction of Sb nanoribbons and their thermoelectric properties from first-principles calculations
Authors: Shen Jin-Ni , Fang Yi , Lin Zi-Xiong , Xie Tian-Zhu , Zhang Yong-Fan , Wu Li-Ming
Published: January 2019

Chemical-bond-driven edge reconstruction of Sb nanoribbons is energetically favorable and helps to stabilize the whole structure. All the nanoribbons are semiconducting, and their thermoelectric properties are enhanced significantly by the edge reconstruction.
Enhanced bactericidal efficacy of polymer stabilized silver nanoparticles in conjugation with different classes of antibiotics
Authors: Kaur Amritpal , Kumar Rajesh
Published: January 2019

The paper presents the interaction mechanism of silver nanoparticles (AgNPs) with different antibiotics and the antibacterial efficacy of the formed conjugates.
Electrorheology of SI-ATRP-modified graphene oxide particles with poly(butyl methacrylate): effect of reduction and compatibility with silicone oil
Authors: Mrlik Miroslav , Ilcikova Marketa , Osicka Josef , Kutalkova Erika , Minarik Antonin , Vesel Alenka , Mosnacek Jaroslav
Published: January 2019

Surface-initiated atom transfer radical polymerization (SI-ATRP) was used to modify graphene oxide (GO) particles with poly(butyl methacrylate) (PBMA) chains.
Re-evaluation of experimental measurements for the validation of electronic band structure calculations for LiFePO4 and FePO4
Authors: Zhang Yin , Alarco Jose A. , Best Adam S. , Snook Graeme A. , Talbot Peter C. , Nerkar Jawahar Y.
Published: January 2019

The surface Li depletion affects the determination of optical gap for LiFePO4, which was previously used for validation of DFT calculations.
Characterization of biochars derived from different materials and their effects on microbial dechlorination of pentachlorophenol in a consortium
Authors: Zhang Chunfang , Zhang Ning , Xiao Zhixing , Li Zhiling , Zhang Dongdong
Published: January 2019

The properties of four biochars and their effects on the microbial reductive dechlorination of PCP were investigated.
Fluorination of neodymium carbonate monohydrate with anhydrous hydrogen fluoride in a Carberry spinning-basket reactor
Authors: Pretorius Ryno , le Roux John , Wagener Kobus , van Vuuren David , Crouse Philip
Published: January 2019

Experimental data show that the fluorination of neodymium carbonate hydrate, using anhydrous hydrogen fluoride to yield the metal trifluoride, is independent of temperature and linearly dependent on the reagent partial pressure.
Surface passivation and point defect control in Cu(In,Ga)Se2 films with a Na2S post deposition treatment for higher than 19% CIGS cell performance
Authors: Kim Seung Tae , Larina Liudmila , Yun Jae Ho , Shin Byungha , Ahn Byung Tae
Published: January 2019

Na2S as a new alkaline source for the PDT process enables CIGS cell with enhanced efficiency of 19.2% by eliminating InCu antisites along with VCu defects.
Energy level-modulated non-fullerene small molecule acceptors for improved VOC and efficiency of inverted perovskite solar cells
Authors: Liu Xiaohui , Li Xiaodong , Zou Yang , Liu He , Wang Lei , Fang Junfeng , Yang Chuluo
Published: January 2019

The efficiency and VOC of inverted perovskite solar cells are regularly improved by non-fullerene small molecule acceptors with modulated energy levels.
Flexible-color tuning and white-light emission in three-, four-, and five-component host/guest co-crystals by charge-transfer emissions as well as effective energy transfers
Authors: Ono Toshikazu , Hisaeda Yoshio
Published: January 2019

A series of multi-color and white-light photoluminescence host/guest cocrystals were prepared by cooperative multi-molecular assemblies.
Endothelin-converting enzyme-1 regulates glucagon-like peptide-1 receptor signalling and resensitisation
Authors: Lu Jing , Willars Gary B.
Published: January 2019

Following nutrient ingestion, glucagon-like peptide 1 (GLP-1) is secreted from intestinal L-cells and mediates anti-diabetic effects, most notably stimulating glucose-dependent insulin release from pancreatic β-cells but also inhibiting glucagon release, promoting satiety and weight reduction and potentially enhancing or preserving β-cell mass. These effects are mediated by the GLP-1 receptor (GLP-1R), which is a therapeutic target in type 2 diabetes. Although agonism at the GLP-1R has been well studied, desensitisation and resensitisation are perhaps less well explored. An understanding of these events is important, particularly in the design and use of novel receptor ligands. Here, using either HEK293 cells expressing the recombinant human GLP-1R or the pancreatic β-cell line, INS-1E with endogenous expressesion of the GLP-1R, we demonstrate GLP-1R desensitisation and subsequent resensitisation following removal of extracellular GLP-1 7-36 amide. Resensitisation is dependent on receptor internalisation, endosomal acidification and receptor recycling. Resensitisation is also regulated by endothelin-converting enzyme-1 (ECE-1) activity, most likely through proteolysis of GLP-1 in endosomes and the facilitation of GLP-1R dephosphorylation and recycling. Inhibition of ECE-1 activity also increases GLP-1-induced activation of extracellular signal-regulated kinase and generation of cAMP, suggesting processes dependent upon the lifetime of the internalised ligand–receptor complex.
The morphology and histology study on rabbit degenerated medial meniscus after posterior cruciate ligament rupture
Authors: Deng Zhenhan , Luo Wei , Gao Shanshan , Liao Zhan , Hu Yihe , He Hongbo , Zhang Can , Li Kanghua
Published: January 2019

The morphology and histology changes in the medial meniscus after posterior cruciate ligament (PCL) rupture are poorly understood. Forty-eight rabbits were divided into matched mode pairs; each rabbit had an experimental side, in which the PCL was transacted, and a control side. At the 4, 8, 16 and 24 weeks after the PCL transection, each of the 12 rabbits was killed. Histology was performed to detect the expression of the tissue inhibitors of metalloproteinases-1 (TIMP-1), matrix metalloproteinase (MMP)-1 and MMP-13 in the medial meniscus. We found that medial meniscus displayed significant degenerative characteristics in morphology. The histological evaluation of the degeneration found that the expression levels of TIMP-1, MMP-1 and MMP-13 in the medial meniscus were higher in the experiment side than those in the control side (P<0.05). The expression of both TIMP-1 and MMP-13 was initially elevated and then decreased. The MMP-1 expression reached its peak swiftly and then maintained a relatively high level. There were clear time-dependent degenerative changes in the histology of the medial meniscus after PCL rupture. The high expression of TIMP-1, MMP-1 and MMP-13 in the cartilage may be responsible for the degeneration, and PCL rupture may trigger meniscus degradation and ultimately osteoarthritis.
Learning the ABCs one at a time: structure and mechanism of ABC transporters
Authors: Ford Robert C. , Beis Konstantinos
Published: January 2019

ATP-binding cassette (ABC) transporters are essential proteins that are found across all kingdoms of life. ABC transporters harness the energy of ATP hydrolysis to drive the import of nutrients inside bacterial cells or the export of toxic compounds or essential lipids across bacteria and eukaryotic membranes. Typically, ABC transporters consist of transmembrane domains (TMDs) and nucleotide-binding domains (NBDs) to bind their substrate and ATP, respectively. The TMDs dictate what ligands can be recognised, whereas the NBDs are the power engine of the ABC transporter, carrying out ATP binding and hydrolysis. It has been proposed that they utilise the alternating access mechanism, inward- to outward-facing conformation, to transport their substrates. Here, we will review the recent progress on the structure determination of eukaryotic and bacterial ABC transporters as well as the novel mechanisms that have also been proposed, that fall out of the alternating access mechanism model.
The role of metal ions in the virulence and viability of bacterial pathogens
Authors: Begg Stephanie L.
Published: January 2019

Metal ions fulfil a plethora of essential roles within bacterial pathogens. In addition to acting as necessary cofactors for cellular proteins, making them indispensable for both protein structure and function, they also fulfil roles in signalling and regulation of virulence. Consequently, the maintenance of cellular metal ion homeostasis is crucial for bacterial viability and pathogenicity. It is therefore unsurprising that components of the immune response target and exploit both the essentiality of metal ions and their potential toxicity toward invading bacteria. This review provides a brief overview of the transition metal ions iron, manganese, copper and zinc during infection. These essential metal ions are discussed in the context of host modulation of bioavailability, bacterial acquisition and efflux, metal-regulated virulence factor expression and the molecular mechanisms that contribute to loss of viability and/or virulence during host-imposed metal stress.
Breast tumour organoids: promising models for the genomic and functional characterisation of breast cancer
Authors: Roelofs Charlotte , Hollande Frédéric , Redvers Richard , Anderson Robin L. , Merino Delphine
Published: January 2019

Until recently, established cancer cell lines have been used extensively in breast cancer research, due largely to the difficulties associated with the manipulation and long-term maintenance in culture of primary tumour cells from patients. The recent development of organoid cultures has provided new opportunities to model and analyse patient samples, allowing the propagation of malignant cells under conditions that resemble the three-dimensional growth of breast tumours. They have proved efficacious in preserving the heterogeneity of primary samples and are emerging as a new model to further characterise the molecular features of breast cancer. Organoids formed from patient-derived cells are now in use for the evaluation of drug sensitivity and to validate disease-causing genomic variations. Here, the advantages and limitations of organoid cultures will be discussed and compared with the parallel development of other two- and three-dimensional culture strategies and with patient-derived xenografts. In particular, we will focus on the molecular characterisation of breast cancer organoids and provide some examples of how they have been used in functional studies.
Keeping the balance in NAD metabolism
Authors: Strømland Øyvind , Niere Marc , Nikiforov Andrey A. , VanLinden Magali R. , Heiland Ines , Ziegler Mathias
Published: January 2019

Research over the last few decades has extended our understanding of nicotinamide adenine dinucleotide (NAD) from a vital redox carrier to an important signalling molecule that is involved in the regulation of a multitude of fundamental cellular processes. This includes DNA repair, cell cycle regulation, gene expression and calcium signalling, in which NAD is a substrate for several families of regulatory proteins, such as sirtuins and ADP-ribosyltransferases. At the molecular level, NAD-dependent signalling events differ from hydride transfer by cleavage of the dinucleotide into an ADP-ribosyl moiety and nicotinamide. Therefore, non-redox functions of NAD require continuous biosynthesis of the dinucleotide. Maintenance of cellular NAD levels is mainly achieved by nicotinamide salvage, yet a variety of other precursors can be used to sustain cellular NAD levels via different biosynthetic routes. Biosynthesis and consumption of NAD are compartmentalised at the subcellular level, and currently little is known about the generation and role of some of these subcellular NAD pools. Impaired biosynthesis or increased NAD consumption is deleterious and associated with ageing and several pathologies. Insults to neurons lead to depletion of axonal NAD and rapid degeneration, partial rescue can be achieved pharmacologically by administration of specific NAD precursors. Restoring NAD levels by stimulating biosynthesis or through supplementation with precursors also produces beneficial therapeutic effects in several disease models. In this review, we will briefly discuss the most recent achievements and the challenges ahead in this diverse research field.
Multilayered control of chromosome replication in Caulobacter crescentus
Authors: Frandi Antonio , Collier Justine
Published: January 2019

The environmental Alphaproteobacterium Caulobacter crescentus is a classical model to study the regulation of the bacterial cell cycle. It divides asymmetrically, giving a stalked cell that immediately enters S phase and a swarmer cell that stays in the G1 phase until it differentiates into a stalked cell. Its genome consists in a single circular chromosome whose replication is tightly regulated so that it happens only in stalked cells and only once per cell cycle. Imbalances in chromosomal copy numbers are the most often highly deleterious, if not lethal. This review highlights recent discoveries on pathways that control chromosome replication when Caulobacter is exposed to optimal or less optimal growth conditions. Most of these pathways target two proteins that bind directly onto the chromosomal origin: the highly conserved DnaA initiator of DNA replication and the CtrA response regulator that is found in most Alphaproteobacteria. The concerted inactivation and proteolysis of CtrA during the swarmer-to-stalked cell transition license cells to enter S phase, while a replisome-associated Regulated Inactivation and proteolysis of DnaA (RIDA) process ensures that initiation starts only once per cell cycle. When Caulobacter is stressed, it turns on control systems that delay the G1-to-S phase transition or the elongation of DNA replication, most probably increasing its fitness and adaptation capacities.
Simple and straightforward realisation of an electronic capacitor
Authors: Mutovkin A. , Yuhimenko V. , Schacham S. , Kuperman A.
Published: January 2019

This Letter proposes a simple realisation of a circuit (referred to as electronic capacitor) capable of emulating large capacitance of controllable value while utilising a much smaller capacitor and a DC–DC converter. The circuit may be used in a plug‐and‐play fashion instead of any real large capacitor within the control bandwidth. The proposed control algorithm forces the terminal voltage of the DC–DC converter to follow the well‐known capacitance equation by sensing the terminal current and simultaneously compensates conversion losses by an auxiliary control loop. The proposed algorithm is successfully verified by emulating bulk DC‐link capacitance of a commercial power factor correction front end.
Planck’s Dusty GEMS
Authors: Nesvadba N. P. H. , Cañameras R. , Kneissl R. , Koenig S. , Yang C. , Le Floc’h E. , Omont A. , Scott D.
Published: January 2019

The bright 3P1–3P0 ([CI] 1–0) and 3P2–3P1 ([CI] 2–1) lines of atomic carbon are becoming more and more widely employed as tracers of the cold neutral gas in high-redshift galaxies. Here we present observations of these lines in the 11 galaxies of the set of Planck’s Dusty GEMS, the brightest gravitationally lensed galaxies on the extragalactic submillimeter sky probed by the Planck satellite. We have [CI] 1–0 and [CI] 2–1 measurements for seven and eight of these galaxies, respectively, including four galaxies where both lines have been measured. We use our observations to constrain the gas excitation mechanism, excitation temperatures, optical depths, atomic carbon and molecular gas masses, and carbon abundances. Ratios of LCI/LFIR are similar to those found in the local universe, and suggest that the total cooling budget through atomic carbon has not significantly changed in the last 12 Gyr. Both lines are optically thin and trace 1 − 6 × 107 M⊙ of atomic carbon. Carbon abundances, XCI, are between 2.5 and 4 × 10−5, for an ultra-luminous infrared galaxy (ULIRG) CO-to-H2 conversion factor of αCO = 0.8 M⊙ / [K km s−1 pc2]. Ratios of molecular gas masses derived from [CI] 1–0 and CO agree within the measurement uncertainties for five galaxies, and agree to better than a factor of two for another two with [CI] 1–0 measurements, after carefully taking CO excitation into account. This does not support the idea that intense, high-redshift starburst galaxies host large quantities of “CO-dark” gas. These results support the common assumptions underlying most molecular gas mass estimates made for massive, dusty, high-redshift starburst galaxies, although the good agreement between the masses obtained with both tracers cannot be taken as independent confirmation of either αCO or XCI.
Inferring physical parameters in solar prominence threads
Authors: Montes-Solís M. , Arregui I.
Published: January 2019

Context. High resolution observations have permitted the resolution of solar prominences/filaments into sets of threads/fibrils. However, the values of the physical parameters of these threads and their structuring remain poorly constrained.

Aims. We use prominence seismology techniques to analyse transverse oscillations in threads by comparing magnetohydrodynamic (MHD) models and observations.

Methods. We applied Bayesian methods to obtain two different types of information. We first inferred the marginal posterior distribution of physical parameters such as the magnetic field strength or length of the thread, when a totally filled tube, partially filled tube, and three damping models are considered as certain; the three damping models are resonant absorption in the Alfvén continuum, resonant absorption in the slow continuum, and Cowling’s diffusion. Then, we compared the relative plausibility between alternative MHD models by computing the Bayes factors.

Results. Well-constrained probability density distributions can be obtained for the magnetic field strength, length of the thread, density contrast, and parameters associated with the damping models. In a comparison of the damping models of resonant absorption in the Alfvén continuum, resonant absorption in the slow continuum, and Cowling’s diffusion due to partial ionisation of prominence plasma, the resonant absorption in the Alfvén continuum is the most plausible mechanism to explain the existing observations. Relations between periods of fundamental and first overtone kink modes with values around 1 are better explained by expressions of the period ratio in the long thread approximation, while the rest of the values are more probable in the short thread limit for the period ratio.

Conclusions. Our results show that Bayesian analysis offers valuable methods to perform parameter inference and a model comparison in the context of prominence seismology.
H2/HD molecular data for analysis of quasar spectra in search of varying constants
Authors: Ubachs W. , Salumbides E. J. , Murphy M. T. , Abgrall H. , Roueff E.
Published: January 2019

Context. Absorption lines of H2 and HD molecules observed at high redshift in the line of sight towards quasars are a test ground to search for variation of the proton-to-electron mass ratio μ. For this purpose, results from astronomical observations are compared with a compilation of molecular data of the highest accuracy, obtained in laboratory studies as well as in first-principles calculations.

Aims. A comprehensive line list is compiled for H2 and HD absorption lines in the Lyman (B1Σu+ − X1Σg+) and Werner (C1Πu − X1Σg+) band systems up to the Lyman cutoff at 912 Å. Molecular parameters listed for each line i are the transition wavelength λi, the line oscillator strength fi, the radiative damping parameter of the excited state Γi, and the sensitivity coefficient Ki for a variation of the proton-to-electron mass ratio.

Methods. The transition wavelengths λi for the H2 and HD molecules are determined by a variety of advanced high-precision spectroscopic experiments involving narrowband vacuum ultraviolet lasers, Fourier-transform spectrometers, and synchrotron radiation sources. Results for the line oscillator strengths fi, damping parameters Γi, and sensitivity coefficients Ki are obtained in theoretical quantum chemical calculations.

Results. A new list of molecular data is compiled for future analyses of cold clouds of hydrogen absorbers, specifically for studies of μ-variation from quasar data. The list is applied in a refit of quasar absorption spectra of B0642–5038 and J1237+0647 yielding constraints on a variation of the proton-to-electron mass ratio Δμ/μ consistent with previous analyses.
La propriété des données génétiques
Authors: Stoeklé Henri-Corto , Forster Ninon , Turrini Mauro , Charlier Philippe , Hervé Christian , Deleuze Jean-François , Vogt Guillaume
Published: January 2019

En France, la donnée génétique n’est pas accessible au travers du droit de la propriété. Elle est assimilée à un élément du corps humain à protéger, et non un bien à valoriser. Pourtant, dans notre monde extrêmement concurrentiel, il est indispensable que la France trouve des solutions lui permettant de valoriser, scientifiquement et économiquement, les données génétiques de façon plus efficiente. Une possibilité serait de définir la donnée génétique comme une information brute dépourvue de valeur d’usage. Ce sera donc le choix d’une valeur d’usage (clinique, scientifique, économique, etc.) obtenue suite à différents processus d’analyse et de traitement significatifs, qui la transformeront en une information utile. Dans ce cas et sous certaines conditions, cette information peut être alors considérée par le droit de la propriété intellectuelle comme une création originale et ainsi être valorisée économiquement, tout en maintenant le même niveau de protection actuel sur les données génétiques. La France a donc le choix entre changer la loi sur la protection des données génétiques, en se rapprochant de l’approche nord-américaine, considérant ces données comme un capital que chacun peut faire fructifier ou vendre, ou établir une distinction franche entre la donnée génétique et l’information.
Terahertz read-only multi-order nonvolatile rewritable photo-memory based on indium oxide nanoparticles
Authors: Ji Hongyu , Wang Wei , Xiong Luyao , Liu Dandan , Lv Longfeng , Zhang Bo , Shen Jingling
Published: January 2019

We investigate terahertz (THz) read-only multi-order nonvolatile rewritable photo-memory based on indium oxide (In2O3) nanoparticles. Optical excitation of an In2O3/quartz sample increases its conductivity, which attenuates its THz transmission. When the optical excitation is terminated, the modulated THz transmission can recover back to its original value in air. However, the THz transmission shows no obvious change over a long-term when In2O3/quartz is encapsulated in an inert gas (nitrogen). Multi-order nonvolatile digital information storage is obtained at different light intensities, and the photo-memory can be rewritten after thermal annealing. Different THz transmissions are used as coded signal units, which are programmed to store information. These results show that THz read-only multi-level nonvolatile rewritable photo-memory can be realized.
Strain engineering of electronic and magnetic properties of double-transition metal ferromagnetic semiconductor MXenes
Authors: Siriwardane Edirisuriya M. D. , Çakir Deniz
Published: January 2019

Strain engineering appears as an effective way to modulate physical and chemical properties of two-dimensional (2D) materials. In contrast to their three-dimensional counterparts, 2D materials can withstand high strain before rapture, which promises unique opportunities to control and tune their electronic, optical, and magnetic properties. Recently predicted Hf2MnC2O2 and Hf2VC2O2 double transition metal ferromagnetic semiconductor MXenes show robust ferromagnetic ground state with high Curie temperature. In this study, we investigated the structural, electronic, and magnetic properties of those 2D materials under the biaxial strain using density functional theory. Both strain free monolayers are indirect bandgap semiconductors. Strain engineering can be exploited to turn semiconductor monolayers into metallic or semi-metallic ones depending on the size and type of the applied strain. For instance, a semiconductor to metal transition occurs at −3% compression and 8% tension in Hf2MnC2O2 and also at −2% compression and 9% tension in Hf2VC2O2. Electron and hole effective masses are able to be tuned significantly. The ferromagnetic phase becomes stronger (weaker) as compared to the anti-ferromagnetic phase of both types of monolayers by applying the biaxial tensile (compressive) strain. Our calculations indicated that the Curie temperature (TC) is highly sensitive to the size and type of strain. TC increases (decreases) with the tensile (compressive) strain. While TC is 444 K at a compressive strain of 4%, it becomes 1577 K at a tensile strain of 8% for Hf2MnC2O2.
Statistical behavior of a single microdischarge in atmospheric-pressure air dielectric barrier discharges
Authors: Lin Kun-Mo , Ku Chun-Ming , Cheng Cheng-Hang
Published: January 2019

This work investigates the statistical behavior including the dimensions and electrical properties of a single microdischarge (MD) generated in a planar atmospheric-pressure air dielectric barrier discharge reactor using a kHz sinusoidal power source with a gap of 1.4 mm. The MD diameters and surface wave (SW) dimensions are captured by an intensified charge-coupled device camera with currents and charge transferred being recorded. The average currents measured in positive and negative half periods (HPs) are 58.9 and 50.5 mA, respectively. The average diameters measured are 256 and 258 μm in positive and negative HPs, respectively. Therefore, the average current densities calculated in positive and negative HPs are 1.14 × 106 and 9.66 × 105 A m−2, respectively. The high current density leads to the high density of surface charge reaching up to 51.5 nC cm−2 in the positive HP at the anode, which is one order of magnitude higher than those observed in filamentary discharges using He/N2 mixtures. The gap dimension is adjusted to 2.0 mm to investigate the effect of the gap dimension on MD properties. Larger MD diameters, currents, SW dimensions, and the charge transferred are measured in the gap of 2.0 mm although the average current densities evaluated in positive and negative HPs are lower than those of gap 1.4 mm as 9.39 × 105 and 8.15 × 105 A m−2, respectively. The average density of surface charge evaluated in the positive HP at the anode of gap 2.0 mm is 51.7 nC cm−2, which is almost identical to that evaluated in the gap of 1.4 mm.
Ballistic and diffusive vibrational energy transport in molecules
Authors: Rubtsov Igor V. , Burin Alexander L.
Published: January 2019

Energy transport in molecules is essential for many areas of science and technology. Strong covalent bonds of a molecular backbone can facilitate the involvement of the molecule’s high-frequency modes in energy transport, which, under certain conditions, makes the transport fast and efficient. We discuss such conditions and describe various transport regimes in molecules, including ballistic, diffusive, directed diffusion, and intermediate regime cases, in light of recently developed experimental and theoretical approaches.
The radius and temperature distribution along radial direction of lightning plasma channel
Authors: An Tingting , Yuan Ping , Liu Guorong , Cen Jianyong , Wang Xuejuan , Zhang Meng , An Yingying
Published: January 2019

Based on various radiation components in the spectra of lightning return stroke processes, the temperature of the lightning channel is diagnosed by different methods. Combining with the synchronized electric field data and optical pictures of the lightning channel, the radii of the core current channel and the luminous channel are estimated. On the basis of the above mentioned facts, according to the heat conduction equation, the channel temperature distribution along the radial direction of the lightning return stroke channel is also achieved. The results from six lightning return strokes show that for the core current channel and luminous channel, the radii are in the range of 0.66–1.01 cm and 5.03–7.96 cm, respectively, and the corresponding channel temperatures are 27 300–30 300 K and 3300–5800 K, respectively. Within an average radius of around 1.76 cm, channel temperatures are above 20 000 K and fall sharply along the radial direction while gradually decline outside this range. The radii of the glowing edge with a temperature of around 500 K are first estimated, around 6.94–13.0 cm.