bluuebunny/crossref_metadata_2025 huggingface dataset:
Exploiting oxidative phosphorylation to promote the stem and immunoevasive properties of pancreatic cancer stem cells
Authors: Valle Sandra , Alcalá Sonia , Martin-Hijano Laura , Cabezas-Sáinz Pablo , Navarro Diego , Muñoz Edurne Ramos , Yuste Lourdes , Tiwary Kanishka , Walter Karolin , Ruiz-Cañas Laura , Alonso-Nocelo Marta , Rubiolo Juan A. , González-Arnay Emilio , Heeschen Christopher , Garcia-Bermejo Laura , Hermann Patrick C. , Sánchez Laura , Sancho Patricia , Fernández-Moreno Miguel Ángel , Sainz Bruno
Published: October 2020

Pancreatic ductal adenocarcinoma (PDAC), the fourth leading cause of cancer death, has a 5-year survival rate of approximately 7–9%. The ineffectiveness of anti-PDAC therapies is believed to be due to the existence of a subpopulation of tumor cells known as cancer stem cells (CSCs), which are functionally plastic, and have exclusive tumorigenic, chemoresistant and metastatic capacities. Herein, we describe a 2D in vitro system for long-term enrichment of pancreatic CSCs that is amenable to biological and CSC-specific studies. By changing the carbon source from glucose to galactose in vitro, we force PDAC cells to utilize OXPHOS, resulting in enrichment of CSCs defined by increased CSC biomarker and pluripotency gene expression, greater tumorigenic potential, induced but reversible quiescence, increased OXPHOS activity, enhanced invasiveness, and upregulated immune evasion properties. This CSC enrichment method can facilitate the discovery of new CSC-specific hallmarks for future development into targets for PDAC-based therapies.
Genome-wide screens identify Toxoplasma gondii determinants of parasite fitness in IFNγ-activated murine macrophages
Authors: Wang Yifan , Sangaré Lamba Omar , Paredes-Santos Tatiana C. , Hassan Musa A. , Krishnamurthy Shruthi , Furuta Anna M. , Markus Benedikt M. , Lourido Sebastian , Saeij Jeroen P. J.
Published: October 2020

Macrophages play an essential role in the early immune response againstToxoplasmaand are the cell type preferentially infected by the parasite in vivo. Interferon gamma (IFNγ) elicits a variety of anti-Toxoplasmaactivities in macrophages. Using a genome-wide CRISPR screen we identify 353Toxoplasmagenes that determine parasite fitness in naїve or IFNγ-activated murine macrophages, seven of which are further confirmed. We show that one of these genes encodes dense granule protein GRA45, which has a chaperone-like domain, is critical for correct localization of GRAs into the PVM and secretion of GRA effectors into the host cytoplasm. Parasites lacking GRA45 are more susceptible to IFNγ-mediated growth inhibition and have reduced virulence in mice. Together, we identify and characterize an important chaperone-like GRA inToxoplasmaand provide a resource for the community to further explore the function ofToxoplasmagenes that determine fitness in IFNγ-activated macrophages.
A bacterial endophyte exploits chemotropism of a fungal pathogen for plant colonization
Authors: Palmieri Davide , Vitale Stefania , Lima Giuseppe , Di Pietro Antonio , Turrà David
Published: October 2020

Soil-inhabiting fungal pathogens use chemical signals released by roots to direct hyphal growth towards the host plant. Whether other soil microorganisms exploit this capacity for their own benefit is currently unknown. Here we show that the endophytic rhizobacteriumRahnella aquatilislocates hyphae of the root-infecting fungal pathogenFusarium oxysporumthrough pH-mediated chemotaxis and uses them as highways to efficiently access and colonize plant roots. Secretion of gluconic acid (GlcA) byR. aquatilisin the rhizosphere leads to acidification and counteractsF. oxysporum-induced alkalinisation, a known virulence mechanism, thereby preventing fungal infection. Genetic abrogation or biochemical inhibition of GlcA-mediated acidification abolished biocontrol activity ofR. aquatilisand restored fungal infection. These findings reveal a new way by which bacterial endophytes hijack hyphae of a fungal pathogen in the soil to gain preferential access to plant roots, thereby protecting the host from infection.
A causal role for frontal cortico-cortical coordination in social action monitoring
Authors: Ninomiya Taihei , Noritake Atsushi , Kobayashi Kenta , Isoda Masaki
Published: October 2020

Decision-making via monitoring others’ actions is a cornerstone of interpersonal exchanges. Although the ventral premotor cortex (PMv) and the medial prefrontal cortex (MPFC) are cortical nodes in social brain networks, the two areas are rarely concurrently active in neuroimaging, inviting the hypothesis that they are functionally independent. Here we show in macaques that the ability of the MPFC to monitor others’ actions depends on input from the PMv. We found that delta-band coherence between the two areas emerged during action execution and action observation. Information flow especially in the delta band increased from the PMv to the MPFC as the biological nature of observed actions increased. Furthermore, selective blockade of the PMv-to-MPFC pathway using a double viral vector infection technique impaired the processing of observed, but not executed, actions. These findings demonstrate that coordinated activity in the PMv-to-MPFC pathway has a causal role in social action monitoring.
Increased RNA editing in maternal immune activation model of neurodevelopmental disease
Authors: Tsivion-Visbord Hadas , Kopel Eli , Feiglin Ariel , Sofer Tamar , Barzilay Ran , Ben-Zur Tali , Yaron Orly , Offen Daniel , Levanon Erez Y.
Published: October 2020

The etiology of major neurodevelopmental disorders such as schizophrenia and autism is unclear, with evidence supporting a combination of genetic factors and environmental insults, including viral infection during pregnancy. Here we utilized a mouse model of maternal immune activation (MIA) with the viral mimic PolyI:C infection during early gestation. We investigated the transcriptional changes in the brains of mouse fetuses following MIA during the prenatal period, and evaluated the behavioral and biochemical changes in the adult brain. The results reveal an increase in RNA editing levels and dysregulation in brain development-related gene pathways in the fetal brains of MIA mice. These MIA-induced brain editing changes are not observed in adulthood, although MIA-induced behavioral deficits are observed. Taken together, our findings suggest that MIA induces transient dysregulation of RNA editing at a critical time in brain development.
A role for spindles in the onset of rapid eye movement sleep
Authors: Bandarabadi Mojtaba , Herrera Carolina Gutierrez , Gent Thomas C. , Bassetti Claudio , Schindler Kaspar , Adamantidis Antoine R.
Published: October 2020

Sleep spindle generation classically relies on an interplay between the thalamic reticular nucleus (TRN), thalamo-cortical (TC) relay cells and cortico-thalamic (CT) feedback during non-rapid eye movement (NREM) sleep. Spindles are hypothesized to stabilize sleep, gate sensory processing and consolidate memory. However, the contribution of non-sensory thalamic nuclei in spindle generation and the role of spindles in sleep-state regulation remain unclear. Using multisite thalamic and cortical LFP/unit recordings in freely behaving mice, we show that spike-field coupling within centromedial and anterodorsal (AD) thalamic nuclei is as strong as for TRN during detected spindles. We found that spindle rate significantly increases before the onset of rapid eye movement (REM) sleep, but not wakefulness. The latter observation is consistent with our finding that enhancing spontaneous activity of TRN cells or TRN-AD projections using optogenetics increase spindle rate and transitions to REM sleep. Together, our results extend the classical TRN-TC-CT spindle pathway to include non-sensory thalamic nuclei and implicate spindles in the onset of REM sleep.
Non-dispersive infrared multi-gas sensing via nanoantenna integrated narrowband detectors
Authors: Tan Xiaochao , Zhang Heng , Li Junyu , Wan Haowei , Guo Qiushi , Zhu Houbin , Liu Huan , Yi Fei
Published: October 2020

Non-dispersive infrared (NDIR) spectroscopy analyzes the concentration of target gases based on their characteristic infrared absorption. In conventional NDIR gas sensors, an infrared detector has to pair with a bandpass filter to select the target gas. However, multiplexed NDIR gas sensing requires multiple pairs of bandpass filters and detectors, which makes the sensor bulky and expensive. Here, we propose a multiplexed NDIR gas sensing platform consisting of a narrowband infrared detector array as read-out. By integrating plasmonic metamaterial absorbers with pyroelectric detectors at the pixel level, the detectors exhibit spectrally tunable and narrowband photoresponses, circumventing the need for separate bandpass filter arrays. We demonstrate the sensing of H2S, CH4, CO2, CO, NO, CH2O, NO2, SO2. The detection limits of common gases such as CH4, CO2, and CO are 63 ppm, 2 ppm, and 11 ppm, respectively. We also demonstrate the deduction of the concentrations of two target gases in a mixture.
Broadband multi-magnon relaxometry using a quantum spin sensor for high frequency ferromagnetic dynamics sensing
Authors: McCullian Brendan A. , Thabt Ahmed M. , Gray Benjamin A. , Melendez Alex L. , Wolf Michael S. , Safonov Vladimir L. , Pelekhov Denis V. , Bhallamudi Vidya P. , Page Michael R. , Hammel P. Chris
Published: October 2020

Development of sensitive local probes of magnon dynamics is essential to further understand the physical processes that govern magnon generation, propagation, scattering, and relaxation. Quantum spin sensors like the NV center in diamond have long spin lifetimes and their relaxation can be used to sense magnetic field noise at gigahertz frequencies. Thus far, NV sensing of ferromagnetic dynamics has been constrained to the case where the NV spin is resonant with a magnon mode in the sample meaning that the NV frequency provides an upper bound to detection. In this work we demonstrate ensemble NV detection of spinwaves generated via a nonlinear instability process where spinwaves of nonzero wavevector are parametrically driven by a high amplitude microwave field. NV relaxation caused by these driven spinwaves can be divided into two regimes; one- and multi-magnon NV relaxometry. In the one-magnon NV relaxometry regime the driven spinwave frequency is below the NV frequencies. The driven spinwave undergoes four-magnon scattering resulting in an increase in the population of magnons which are frequency matched to the NVs. The dipole magnetic fields of the NV-resonant magnons couple to and relax nearby NV spins. The amplitude of the NV relaxation increases with the wavevector of the driven spinwave mode which we are able to vary up to 3 × 106 m−1, well into the part of the spinwave spectrum dominated by the exchange interaction. Increasing the strength of the applied magnetic field brings all spinwave modes to higher frequencies than the NV frequencies. We find that the NVs are relaxed by the driven spinwave instability despite the absence of any individual NV-resonant magnons, suggesting that multiple magnons participate in creating magnetic field noise below the ferromagnetic gap frequency which causes NV spin relaxation.
Mineralogy of microbially induced calcium carbonate precipitates formed using single cell drop-based microfluidics
Authors: Zambare Neerja M. , Naser Nada Y. , Gerlach Robin , Chang Connie B.
Published: October 2020

Microbe-mineral interactions are ubiquitous and can facilitate major biogeochemical reactions that drive dynamic Earth processes such as rock formation. One example is microbially induced calcium carbonate precipitation (MICP) in which microbial activity leads to the formation of calcium carbonate precipitates. A majority of MICP studies have been conducted at the mesoscale but fundamental questions persist regarding the mechanisms of cell encapsulation and mineral polymorphism. Here, we are the first to investigate and characterize precipitates on the microscale formed by MICP starting from single ureolytic E. coli MJK2 cells in 25 µm diameter drops. Mineral precipitation was observed over time and cells surrounded by calcium carbonate precipitates were observed under hydrated conditions. Using Raman microspectroscopy, amorphous calcium carbonate (ACC) was observed first in the drops, followed by vaterite formation. ACC and vaterite remained stable for up to 4 days, possibly due to the presence of organics. The vaterite precipitates exhibited a dense interior structure with a grainy exterior when examined using electron microscopy. Autofluorescence of these precipitates was observed possibly indicating the development of a calcite phase. The developed approach provides an avenue for future investigations surrounding fundamental processes such as precipitate nucleation on bacteria, microbe-mineral interactions, and polymorph transitions.
On the link between the topside ionospheric effective scale height and the plasma ambipolar diffusion, theory and preliminary results
Authors: Pignalberi Alessio , Pezzopane Michael , Nava Bruno , Coïsson Pierdavide
Published: October 2020

Over the years, an amount of models relying on effective parameters were implemented in the challenging issue of the topside ionosphere description. These models are based on different analytical functions, but all of them depend on a parameter called effective scale height, that is deduced from topside electron density measurements. As their names state, they are effective in reproducing the topside electron density profile only when applied to the analytical function used to derive them. Then, in principle, they do not have any physical meaning. It is the goal of this paper to mathematically link the effective scale height modeled through the Epstein layer to the vertical scale height theoretically deduced from the plasma ambipolar diffusion theory. Firstly, effective and theoretical scale heights are linked through a mathematical relation by showing that they tend to each other in the topside ionosphere. Secondly, their connection is preliminarily demonstrated by calculating effective scale height values from the entire COSMIC/FORMOSAT-3 radio occultation dataset. Thirdly, a possible connection between the vertical gradient of the topside scale height (as obtained by COSMIC/FORMOSAT-3 satellites) and the electron temperature (as obtained by ESA Swarm B satellite) is studied by highlighting corresponding similarities in the diurnal, seasonal, solar activity, and latitudinal variability.
Synthesis, characterization and photothermal analysis of nanostructured hydrides of Pd and PdCeO2
Authors: Cruz Cláudia C. R. , da Silva Nilton P. , Castilho Amanda V. , Favre-Nicolin Viviane A. , Cesar Claudio L. , Orlande Helcio R. B. , Dos Santos Dilson S.
Published: October 2020

Hyperthermia was shown to be an important co-adjuvant therapy to conventional cancer treatments. Nanoparticles can be used in the hyperthermia therapy to improve the localized absorption of energy imposed by external sources, in order to kill tumor cells solely by the effect of heat and with minimum thermal damage to surrounding healthy cells. Nanoparticles can also serve as carriers of drugs that specifically act on the tumor when heated, including hydrogen that can be desorbed to locally promote an antioxidant effect and reduce the viability of cancer cells. In this context, palladium hydride nanoparticles emerge as promising materials for the hyperthermia therapy. In this study, palladium nanocubes (PdNC) and PdCeO2 nanoparticles were synthesized. Nanofluids produced with these nanomaterials were hydrogenated and then tested to examine their photothermal effects. Nanofluids made of PdHx nanoparticles presented significant temperature increases of more than 30 °C under 3 min of diode-laser irradiation. On the other hand, nanofluids with PdCeO2H nanoparticles presented temperature increases around 11 °C under the same experimental conditions. The behavior observed with the PdCeO2H nanofluids can be attributed to the effect of H+ in reducing Ce+4 to Ce+3.
Light absorption enhancement in ultrathin film solar cell with embedded dielectric nanowires
Authors: Elrabiaey Mahmoud A. , Hussein Mohamed , Hameed Mohamed Farhat O. , Obayya Salah S. A.
Published: October 2020

A novel design of thin-film crystalline silicon solar cell (TF C-Si-SC) is proposed and numerically analyzed. The reported SC has 1.0 µm thickness of C-Si with embedded dielectric silicon dioxide nanowires (NWs). The introduced NWs increase the light scattering in the active layer which improves the optical path length and hence the light absorption. The SC geometry has been optimized using particle swarm optimization (PSO) technique to improve the optical and electrical characteristics. The suggested TF C-Si-SC with two embedded NWs offers photocurrent density ($${J}_{ph}$$

J

ph

) of 32.8 mA cm−2 which is higher than 18 mA cm−2 of the conventional thin film SC with an enhancement of 82.2%. Further, a power conversion efficiency of 15.9% is achieved using the reported SC.
Caspase inhibition rescues F1Fo ATP synthase dysfunction-mediated dendritic spine elimination
Authors: Chen Hao , Tian Jing , Guo Lan , Du Heng
Published: October 2020

Dendritic spine injury underlies synaptic failure in many neurological disorders. Mounting evidence suggests a mitochondrial pathway of local nonapoptotic caspase signaling in mediating spine pruning. However, it remains unclear whether this caspase signaling plays a key role in spine loss when severe mitochondrial functional defects are present. The answer to this question is critical especially for some pathological states, in which mitochondrial deficits are prominent and difficult to fix. F1Fo ATP synthase is a pivotal mitochondrial enzyme and the dysfunction of this enzyme involves in diseases with spinopathy. Here, we inhibited F1Fo ATP synthase function in primary cultured hippocampal neurons by using non-lethal oligomycin A treatment. Oligomycin A induced mitochondrial defects including collapsed mitochondrial membrane potential, dissipated ATP production, and elevated reactive oxygen species (ROS) production. In addition, dendritic mitochondria underwent increased fragmentation and reduced positioning to dendritic spines along with increased caspase 3 cleavage in dendritic shaft and spines in response to oligomycin A. Concurring with these dendritic mitochondrial changes, oligomycin A-insulted neurons displayed spine loss and altered spine architecture. Such oligomycin A-mediated changes in dendritic spines were substantially prevented by the inhibition of caspase activation by using a pan-caspase inhibitor, quinolyl-valyl-O-methylaspartyl-[-2,6-difluorophenoxy]-methyl ketone (Q-VD-OPh). Of note, the administration of Q-VD-OPh showed no protective effect on oligomycin A-induced mitochondrial dysfunction. Our findings suggest a pivotal role of caspase 3 signaling in mediating spine injury and the modulation of caspase 3 activation may benefit neurons from spine loss in diseases, at least, in those with F1Fo ATP synthase defects.
Evaluation of blood gene expression levels in facioscapulohumeral muscular dystrophy patients
Authors: Signorelli M. , Mason A. G. , Mul K. , Evangelista T. , Mei H. , Voermans N. , Tapscott S. J. , Tsonaka R. , van Engelen B. G. M. , van der Maarel S. M. , Spitali P.
Published: October 2020

Facioscapulohumeral muscular dystrophy (FSHD) is caused by the expression ofDUX4in skeletal muscles. A number of therapeutic approaches are being developed to antagonize the events preceding and followingDUX4expression that leads to muscular dystrophy. Currently, the possibility to evaluate treatment response in clinical trials is hampered by the lack of objective molecular biomarkers connecting the disease cause to clinical performance. In this study we employed RNA-seq to examine gene expression in PAXgene tubes obtained from two independent cohorts of FSHD patients. Analysis of gene expression profiles did not lead to the identification of genes or pathways differentially expressed in FSHD patients, or associated with disease severity. In particular, we did not find evidence that theDUX4andPAX7signatures were differentially expressed. On the other hand, we were able to improve patient classification by including single genes or groups of genes in classification models. The best classifier wasROPN1L, a gene known to be expressed in testis, coincidentally the typical location ofDUX4expression. These improvements in patient classification hold the potential to enrich the FSHD clinical trial toolbox.
Integration of geoscience frameworks into digital pathology analysis permits quantification of microarchitectural relationships in histological landscapes
Authors: Kendall Timothy J. , Duff Catherine M. , Thomson Andrew M. , Iredale John P.
Published: October 2020

Although gold-standard histological assessment is subjective it remains central to diagnosis and clinical trial protocols and is crucial for the evaluation of any preclinical disease model. Objectivity and reproducibility are enhanced by quantitative analysis of histological images but current methods require application-specific algorithm training and fail to extract understanding from the histological context of observable features. We reinterpret histopathological images as disease landscapes to describe a generalisable framework defining topographic relationships in tissue using geoscience approaches. The framework requires no user-dependent training to operate on all image datasets in a classifier-agnostic manner but is adaptable and scalable, able to quantify occult abnormalities, derive mechanistic insights, and define a new feature class for machine-learning diagnostic classification. We demonstrate application to inflammatory, fibrotic and neoplastic disease in multiple organs, including the detection and quantification of occult lobular enlargement in the liver secondary to hilar obstruction. We anticipate this approach will provide a robust class of histological data for trial stratification or endpoints, provide quantitative endorsement of experimental models of disease, and could be incorporated within advanced approaches to clinical diagnostic pathology.
Substrate-dependent fish have shifted less in distribution under climate change
Authors: Roberts Sarah M. , Boustany Andre M. , Halpin Patrick N.
Published: October 2020

Analyses of the impacts of climate change on fish species have primarily considered dynamic oceanographic variables that are the output of predictive models, yet fish species distributions are determined by much more than just variables such as ocean temperature. Functionally diverse species are differentially influenced by oceanographic as well as physiographic variables such as bottom substrate, thereby influencing their ability to shift distributions. Here, we show that fish species distributions that are more associated with bottom substrate than other dynamic environmental variables have shifted significantly less over the last 30 years than species whose distributions are associated with bottom salinity. Correspondingly, species whose distributions are primarily determined by bottom temperature or ocean salinity have shifted their mean centroid and southern and northern range boundaries significantly more than species whose distributions are determined by substrate or depth. The influence of oceanographic versus static variables differs by species functional group, as benthic species distributions are more associated with substrate and they have shifted significantly less than pelagic species whose distributions are primarily associated with ocean temperatures. In conclusion, benthic fish, that are more influenced by substrate, may prove much less likely to shift distributions under future climate change.
Tailored electrocatalysts by controlled electrochemical deposition and surface nanostructuring
Authors: Sebastián-Pascual Paula , Jordão Pereira Inês , Escudero-Escribano María
Published: October 2020

Atomic representation of tailored electrocatalysts: near-surface alloy (top), shaped nanoparticles (right), atomic ensembles (bottom) and deposited metallic adlayers (left).
Potential of N2/O2atmospheric pressure needle-water DC microplasmas for nitrogen fixation: nitrite-free synthesis of nitrates
Authors: Pattyn C. , Maira N. , Remy A. , Roy N. C. , Iseni S. , Petitjean D. , Reniers F.
Published: October 2020

Nitrates are synthesized without residual nitrites in a DC microplasma–water system operated with a water cathode.
Ultrafast pump–probe spectroscopy of neutral FenOm clusters (n, m < 16)
Authors: Garcia Jacob M. , Shaffer Ryan E. , Sayres Scott G.
Published: October 2020

The femtosecond dynamics of iron oxide clusters are shown to depend on both the cluster size and Fe oxidation state.
Modulation of band alignment with water redox potentials by biaxial strain on orthorhombic NaTaO3thin films
Authors: Kraus Alexandre Olivieri , Portugal Guilherme Ribeiro , Arantes Jeverson Teodoro
Published: October 2020

Photocatalysis-assisted water splitting using semiconductor materials greatly depends on the bandgap size and the alignment of band edges relative to the reaction potentials.
A cytotoxic nitrido-osmium(vi) complex induces caspase-mediated apoptosis in HepG2 cancer cells
Authors: Huang Wan-Qiong , Wang Chuan-Xian , Liu Tao , Li Zi-Xin , Pan Chen , Chen Yun-Zhou , Lian Xin , Man Wai-Lun , Ni Wen-Xiu
Published: October 2020

A structurally fine-tuned nitridoosmium(vi) complex induces HepG2 cell apoptosis through activation of the mitochondrial pathway and death receptor pathway, showing promising in vitro and in vivo anticancer activities.
An automated microfluidic system for efficient capture of rare cells and rapid flow-free stimulation
Authors: Dettinger Philip , Wang Weijia , Ahmed Nouraiz , Zhang Yang , Loeffler Dirk , Kull Tobias , Etzrodt Martin , Lengerke Claudia , Schroeder Timm
Published: October 2020

An automated system for efficient capture and culture of rare cells and rapid flow-free manipulation of environmental stimuli.
Double-peak signal features in microfluidic impedance flow cytometry enable sensitive measurement of cell membrane capacitance
Authors: Mahesh Karthik , Varma Manoj , Sen Prosenjit
Published: October 2020

In a microfluidic impedance cytometer with co-planar microelectrodes, frequency-dependent signal features of reactive impedance were found to be highly sensitive to cell membrane capacitance and subsequently used to distinguish cell populations.
Synthesis of recoverable thermosensitive Fe3O4 hybrid microgels with controllable catalytic activity
Authors: Chen Jing , Ma Xiaozhen , Gnanasekar Pitchaimari , Qin Dongdong , Luo Qing , Sun Zhong , Zhu Jin , Yan Ning
Published: October 2020

High-efficiency recoverable catalytic magnetite microgel particles, comprising a magnetic Fe3O4 nanoparticle (NP) core with a thermo-sensitive poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) polymer shell, were synthesized through a four-step procedure.
One-dimensional polymeric iodoplumbate hybrids with lanthanide complex cations: syntheses, crystal structures, and photoelectric and photocatalytic properties
Authors: Chen Niannian , Gao Yan , Tian Yiming , Wu Bing , Jia Dingxian , Zhao Shengxian
Published: October 2020

New iodoplumbate hybrids were prepared using lanthanide complexes as SDAs. They exhibit a high photocurrent response, current density and photocatalytic activity in the degradation of CV.
DNA hybridization as a general method to enhance the cellular uptake of nanostructures
Authors: Li Hongyan , Fan Jilin , Buhl Eva Miriam , Huo Shuaidong , Loznik Mark , Göstl Robert , Herrmann Andreas
Published: October 2020

DNA hybridization provides a simple and generalizable strategy to enhance the cellular internalization of nanostructures.
Minimising damage in high resolution scanning transmission electron microscope images of nanoscale structures and processes
Authors: Nicholls Daniel , Lee Juhan , Amari Houari , Stevens Andrew J. , Mehdi B. Layla , Browning Nigel D.
Published: October 2020

Determining the optimum electron dose distribution for damage mitigated scanning transmission electron microscopy imaging using subsampling and image inpainting.
Poly(vinyl acetate-co-ethylene) particles prepared by surfactant-free emulsion polymerization in the presence of a hydrophilic RAFT/MADIX macromolecular chain transfer agent
Authors: Delorme James , Boyron Olivier , Dugas Pierre-Yves , Dufils Pierre-Emmanuel , Wilson D. James , Monteil Vincent , D'Agosto Franck , Lansalot Muriel
Published: October 2020

Poly(vinyl acetate-co-ethylene) latexes are prepared under a broad range of conditions by emulsion polymerization in the presence of a hydrophilic RAFT/MADIX macromolecular chain transfer agent.
Topological prediction of palladium coordination cages
Authors: Poole David A. , Bobylev Eduard O. , Mathew Simon , Reek Joost N. H.
Published: October 2020

A molecular mechanics approach enables the accurate prediction of polyhedral topology for homoleptic and heteroleptic palladium MxL2x coordination cages, allowing for new insight and design when considering endo- and exo-hedral functionalization.
Rh(iii)-catalyzed tandem annulative redox-neutral arylation/amidation of aromatic tethered alkenes
Authors: Chen Chao , Shi Chen , Yang Yaxi , Zhou Bing
Published: October 2020

A rhodium(iii)-catalyzed tandem annulative arylation/amidation reaction of aromatic tethered alkenes was developed to deliver a variety of 2,3-dihydro-3-benzofuranmethanamine derivatives.
Cobalt-catalyzed intramolecular decarbonylative coupling of acylindoles and diarylketones through the cleavage of C–C bonds
Authors: Yu Tian-Yang , Xu Wen-Hua , Lu Hong , Wei Hao
Published: October 2020

A method for cobalt–N-heterocyclic carbene catalytic systems for the intramolecular decarbonylative coupling of ketones was achieved.
Retrieval Practice and Word Learning in Children With Specific Language Impairment and Their Typically Developing Peers
Authors: Leonard Laurence B. , Deevy Patricia
Published: October 2020

Purpose

In this article, we review the role of retrieval practice on the word learning and retention of children with specific language impairment (SLI).

Method

Following a brief review of earlier findings on word learning in children with SLI and the assumptions behind retrieval practice, four experiments are described that compared novel words learned in a repeated spaced retrieval condition and those learned in either a repeated study condition or a repeated immediate retrieval condition. Preschool-age children with SLI and their same-age peers with typical language development were the participants in all experiments. The effects of repeated spaced retrieval were assessed through measures of recall of word form and meaning and, receptively, through both picture-pointing and electrophysiological measures.

Results

Repeated spaced retrieval resulted in greater recall of word form and meaning across the experiments. This advantage was seen not only for word–picture pairs used during the learning period but also when generalization of the word to new pictures was required. Receptive testing through picture pointing showed similar results, though in some experiments, ceiling effects rendered this measure less sensitive to differences. An alternative receptive measure—the N400 elicited during picture–word mismatches—showed evidence at the neural level favoring repeated spaced retrieval. The advantages of repeated spaced retrieval were seen in both children with SLI and their typically developing age mates.

Conclusion

Future efforts are warranted to refine and extend the experiments reviewed here. If these efforts prove successful, procedures that incorporate repeated spaced retrieval into more naturalistic clinical and educational activities might be an appropriate next step.

Presentation Video

https://doi.org/10.23641/asha.13063730
Functional and Structural Aging of the Vestibular System
Authors: Jones Sherri M.
Published: October 2020

Purpose

Aging is ubiquitous and the elderly population (aged 65 years and older) will continue to grow, reaching an estimated 25% of the U.S. population by 2060. Symptoms of dizziness and imbalance as well as risk of falling are more common in older adults, but it is often unclear whether these symptoms are due to disease or a consequence of aging. Indeed, age-related changes in the vestibular periphery are not well understood. This invited review describes age-related changes in peripheral vestibular function, comparisons between aging of auditory and vestibular function, structural correlates for vestibular aging, and the role of genetics in vestibular aging.

Conclusion

The data from animal models will show that gravity receptor function declines with age but at different rates for different inbred mouse strains. Gravity receptor aging includes loss of postsynaptic elements and loss of hair cells, which is observed at advanced ages. Loss of hair cells may contribute to some extent at advanced ages. Age-related changes in hearing do not predict age-related changes in vestibular function. Genes likely influence the rate of decline in vestibular function. Further research is needed to fully understand the fundamental mechanisms of vestibular aging and to begin to develop potential therapeutic approaches.
Probing episodic accretion with chemistry: CALYPSO observations of the very-low-luminosity Class 0 protostar IRAM 04191+1522
Authors: Anderl S. , Maret S. , Cabrit S. , Maury A. J. , Belloche A. , André Ph. , Bacmann A. , Codella C. , Podio L. , Gueth F.
Published: October 2020

Context. The process of mass accretion in the earliest phases of star formation is still not fully understood: does the accretion rate smoothly decline with the age of the protostar or are there short, intermittent accretion bursts? The latter option would also yield the possibility for very low-luminosity objects (VeLLOs) to be precursors of solar-type stars, even though they do not seem to have sufficiently high accretion rates to reach stellar masses during their protostellar lifetime. Nevertheless, probing such intermittent events in the deeply embedded phase is not easy. Chemical signatures in the protostellar envelope can trace a past accretion burst.

Aims. We aim to explore whether or not the observed C18O and N2H+ emission pattern towards the VeLLO IRAM 04191+1522 can be understood in the framework of a scenario where the emission is chemically tracing a past accretion burst.

Methods. We used high-angular-resolution Plateau de Bure Interferometer (PdBI) observations of C18O and N2H+ towards IRAM 04191+1522 that were obtained as part of the CALYPSO IRAM Large Program (Continuum And Lines in Young ProtoStellar Objects). We model these observations using a chemical code with a time-dependent physical structure coupled with a radiative transfer module, where we allow for variations in the source luminosity.

Results. We find that the N2H+ line emission shows a central hole, with the N2H+ emission peaking at a radius of about 10′′ (1400 au) from the source, while the C18O emission is compact (1.3′′ FWHM, corresponding to 182 au). The morphology of these two lines cannot be reproduced with a constant luminosity model based on the present-day internal luminosity (0.08 L⊙). However, the N2H+ peaks are consistent with a constant-luminosity model of 12 L⊙. Using a model with time-dependent temperature and density profiles, we show that the observed N2H+ peak emission could indeed be caused by a past accretion burst with a luminosity 150 times higher than the present-day luminosity. Such a burst should have occurred a couple of hundred years ago.

Conclusions. We suggest that an accretion burst occurred in IRAM 04191+1522 in the recent past. If such bursts are common and sufficiently long in VeLLOs, they could lead to higher accretion onto the central object than their luminosity suggests. For IRAM 04191 in particular, our results yield an estimated final mass of 0.2–0.25 M⊙ by the end of the Class 0 phase, which would make this object a low-mass star rather than a brown dwarf. More generally, our analysis demonstrates that the combination of observations of N2H+ and C18O is a more reliable diagnostic of past outburst activity than C18O or N2H+ emission alone.
Increasing the achievable contrast of infrared interferometry with an error correlation model
Authors: Kammerer J. , Mérand A. , Ireland M. J. , Lacour S.
Published: October 2020

Context. Interferometric observables are strongly correlated, yet it is common practice to ignore these correlations in the data analysis process.

Aims. We develop an empirical model for the correlations present in Very Large Telescope Interferometer GRAVITY data and show that properly accounting for them yields fainter detection limits and increases the reliability of potential detections.

Methods. We extracted the correlations of the (squared) visibility amplitudes and the closure phases directly from intermediate products of the GRAVITY data reduction pipeline and fitted our empirical models to them. Then, we performed model fitting and companion injection and recovery tests with both simulated and real GRAVITY data, which are affected by correlated noise, and compared the results when ignoring the correlations and when properly accounting for them with our empirical models.

Results. When accounting for the correlations, the faint source detection limits improve by a factor of up to ∼2 at angular separations > 20 mas. For commonly used detection criteria based on χ2 statistics, this mostly results in claimed detections being more reliable.

Conclusions. Ignoring the correlations present in interferometric data is a dangerous assumption which might lead to a large number of false detections. The commonly used detection criteria (e.g. in the model fitting pipeline CANDID) are only reliable when properly accounting for the correlations; furthermore, instrument teams should work on providing full covariance matrices instead of statistically independent error bars as part of the official data reduction pipelines.
Centrifuge tests to evaluate the effect of depth of water table on seismic response of shallow foundations on silty sands
Authors: Borghei Amin , Ghayoomi Majid , Turner Matthew
Published: October 2020

A set of dynamic centrifuge experiments were performed to assess the effect of the depth of the groundwater table on the seismic site response of silty sand. Silty sand was prepared in a laminar container. The testing program consists of experiments on dry as well as saturated soils and a test, which the groundwater table was below the soil surface. The specimens were spun in a centrifuge, then they were excited with a suite of seismic motions. Results show that 1) while the for peak ground acceleration amplification factor of the saturated soil was smaller than those for the dry soil, the Arias intensity amplification factor of the saturated soil was larger than those for dry soil. 2) as the depth of the groundwater table increased, peak ground amplification factor and short-period amplification factors increased, the mid-period amplification factors decreased. 3) the depth of the groundwater table influences the frequency content of the free field motion. 4) the unsaturated soil behaved stiffer than dry and saturated soils.
Calibration of a simple 1D model for the hydraulic response of regional dykes in the Netherlands
Authors: Chao Ching-Yu , Bakker Maarten , Jommi Cristina
Published: October 2020

A simple numerical model was set up to investigate the hydraulic behaviour of a regional dyke to improve understanding of the response under variable atmospheric conditions. The unsaturated hydraulic properties of the dyke body and the relevant foundation layers were calibrated either on the results of laboratory tests or on a national database, namely the Staringreeks, compiled for typical Dutch soils. The boundary conditions were imposed according to the weather history at the top, and to the pore pressures measured in the field at the bottom of the representative soil column. The results indicate that a simple 1D model is able to accurately reproduce the suction time history in the dyke core, provided the hydraulic conductivity and soil water retention properties are properly calibrated. The optimised hydraulic conductivities are typically two orders of magnitude higher than the saturated hydraulic conductivity from the laboratory tests, but comparable to the ones suggested in the database developed on field data. The work highlights that cautious evaluation of laboratory data is needed for field applications, and that direct information from the field should be used to validate numerical models in the presence of organic soils.
Field and laboratory investigation of rainfall-triggered slope failure in unsaturated loess soils, New Zealand
Authors: Yates Katherine , Russell Adrian , Fentonl Clark
Published: October 2020

Shallow rainfall triggered slope failures occur frequently in loess and loess-derived deposits across the South Island, New Zealand. These failures, which occur in both natural slopes and engineered cuttings, impact road infrastructure, residential housing and rural land use. When dry, the loess can form near vertical cuttings. However, with increase in moisture content loess slopes become susceptible to shallow slope failures. To date, the influence of negative pore-water pressure (suction) on the stability of loess slopes in New Zealand has not been well understood. In this paper, data from long term in situ field monitoring of rainfall, suction and volumetric water content from a loess slope in Banks Peninsula, Canterbury are presented with laboratory triaxial test results undertaken on undisturbed unsaturated loess samples. Field and laboratory soil responses to wetting and drying are compared, and the characteristics of rainfall events which reduce suction in situ and therefore slope stability are discussed.
Long-term suction measurements in Greece & Cyprus. A continuous update
Authors: Bardanis Michael , Loukidis Dimitrios
Published: October 2020

The occurrence of unsaturated soils in the field has been well documented worldwide by measurements of the degree of saturation on samples taken during geotechnical investigations. On the other hand, the suction of unsaturated soils in the field, especially as part of long-term measurements, is documented very rarely and references on the subject are very few and for very few places around the world. The scarceness of this kind of measurements denies researchers perception of the anticipated suction and its possible loss or retention as a result of climatic conditions, especially in countries with warm temperate climate. Suction measurements from temporary and permanent stations in Greece and Cyprus are presented in the paper. From these -admittedly few-measurements until today, the large magnitude of suction that may occur both during summer and winter is presented, along with the possibility of long periods of these suctions being maintained. Another consequence is the range of suction values that sensors should be able to measure in regions of similar climatic conditions in order to cover the range of expected values as obtained from the measurements available so far.
An extended generalized effective stress for active clays
Authors: Tuttolomondo Angelica , Ferrari Alessio , Laloui Lyesse
Published: October 2020

An effective stress concept for active clays is formulated to improve the modelling of these materials under a variety of environmental conditions. In particular, the mechanical effects induced by a change in the chemical potential of pore water associated with a change of its pressure (even in the negative range), as well as a change of its chemical composition, are considered. Some implications of the proposed framework are shown with reference to shear strength results related to unsaturated conditions. The proposed approach allows to describe the shear strength envelope consistently by using a unique set of shear strength parameters irrespective of the pore water chemical composition and of the saturation state.
Theoretical modelling of retention curve for Livet-Gavet loam
Authors: Monnet Jacques , Boutonnier Luc , Taïbi Said , Mahmutovic Dino , Branque Denis
Published: October 2020

Different approaches have been used for modeling retention curves. The experimental correlation was first proposed [1-3]. The physical modelling of unsaturated soils is used for this study. The shape of the retention curve is a consequence of physical assumptions. The paper presents a theoretical model based on elastic spherical particle arrangement. Firstly, a uniform model is presented with a single diameter of soil particle. The second step extends the use of the model to graded soils. The model uses only physical parameters easy to measure. The model is compared with the experimental retention curve of two different samples, the Livet-Gavet loam (1.61m-3mm) as paste and the Gavet sandy loam compacted with 85 falls per layer of Proctor weight. It shows its ability to model the experimental curves. It is of great interest for engineers as it uses only physical parameters. It gives a direct determination of the retention curve along the wetting path and along the drying path. It shows also the importance of adsorbed water to describe the retention curve.
Evaluation of direct shear strength of compacted bentonite having pore-water pressure
Authors: Nishimura Tomoyoshi , Fukaya Masaaki
Published: October 2020

Safety of great deep repository design has been investigated for high-level radioactive waste disposal system in several countries such as Belgium, Canada, China, France, Germany, Japan, Sweden and Switzerland. The repository of the disposal is in most cases based on the concept of a multi-barrier system using the host rock barrier formation and a man-made barrier formation. The man-made barrier consists of high expansive bentonite. Thermal-hydro-mechanical behaviour simulation models were developed, including some parameters described by experimental works. The complex phenomena due to the transition into saturation and chemical reactions at the bentonite barrier system have been explained. This study focused on direct shear strength for compacted bentonite related to some factors induced by uncertainty problems such as hydration effect and pore-water pressure. Measured shear strength properties of compacted bentonite had been determined at high suction values. Also, it is clear that there is some influence of direct shear speed on direct shear strength both under unsaturated-saturated conditions. A modified direct shear apparatus was used in this study to observe changes in shear strength with increments of pore-water pressures.
Tensile strength of a vegetated and partially saturated soil
Authors: Fraccica Alessandro , Romero Enrique , Fourcaud Thierry , Sondon Mercedes , Gandarillas Luis
Published: October 2020

Vegetated soil’s shear strength has been usually assessed through direct shear tests and under triaxial compression stress paths while less is known about its behaviour under tensile stress. Tensile strength and shrinkage-induced cracking play a crucial role in the hydro-mechanical response of earth structures exposed to drying/wetting cycles. For this purpose, a new device for direct tensile tests has been designed and used to let plants grow in compacted soil samples. The equipment consists of two cylindrical moulds connected to each other by a soil bridge in which failure upon pulling is induced due to geometrical constraints. Different soil’s mechanical responses were observed depending on whether suction was low or high. Indeed, it was detected an increase of soil tensile strength and a more brittle behaviour as suction was increasing. However, at the same suction, vegetated soil’s response was more ductile than that of the corresponding bare soil. Results were analysed within a shear strength criterion for partially saturated soils. The analysis evidenced an increase in shear strength in the vegetated soil. A correlation was found between this increase and the roots’ mechanical and morphological features.