bluuebunny/crossref_metadata_2025 huggingface dataset:
A reusable PMMA/paper hybrid plug-and-play microfluidic device for an ultrasensitive immunoassay with a wide dynamic range
Authors: Sanjay Sharma T. , Li Meihan , Zhou Wan , Li Xiaochun , Li XiuJun
Published: June 2020

Conventional colorimetric enzyme-linked immunosorbent assay (ELISA) is a time-consuming laboratory assay that is not very sensitive and consumes a large amount of samples. Herein, the development of a reusable, cost-effective, and eco-friendly poly(methyl methacrylate) (PMMA)/paper hybrid plug-and-play (PnP) device for high-sensitivity immunoassay by analyte enrichment and efficient passing-through washing has been reported. The PMMA device has multiple slots where a pre-patterned paper substrate can be inserted. The sample flows back-and-forth through a low-cost, 3D paper substrate within the PMMA channels, thereby enhancing the amount of analyte adsorbed and dramatically increasing the sensitivity while decreasing the assay time. After the enrichment assay, the paper substrate can simply be pulled out of the device, and the results can be qualitatively viewed with the naked eye or scanned through a simple desktop scanner for quantitative analysis. The paper substrate can be replaced with a new substrate so that the device can be reused. The limits of detection (LODs) of 200 pg/mL for immunoglobulin G (IgG) and 270 pg/mL for hepatitis B surface antigen (HBsAg) were obtained. This IgG assay is at least 10 times more sensitive than commercial ELISA kits. In addition, the PnP ELISA exhibited a significant increase in the linear dynamic range from 3 orders of magnitude in a common paper-based device to a wide range of six orders of magnitude in the PnP hybrid device. This reusable PnP device has great potential for the low-cost yet high-sensitivity detection of infectious diseases, cancers, and other important biomolecules.
Low motional impedance distributed Lamé mode resonators for high frequency timing applications
Authors: Daruwalla Anosh , Wen Haoran , Liu Chang-Shun , Ayazi Farrokh
Published: June 2020

This paper presents a novel high-Q silicon distributed Lamé mode resonator (DLR) for VHF timing reference applications. The DLR employs the nature of shear wave propagation to enable a cascade of small square Lamé modes in beam or frame configurations with increased transduction area. Combined with high efficiency nano-gap capacitive transduction, it enables low motional impedances while scaling the frequency to VHF range. The DLR designs are robust against common process variations and demonstrate high manufacturability across different silicon substrates and process specifications. Fabricated DLRs in beam and frame configurations demonstrate high performance scalability with high Q-factors ranging from 50 to 250 k, motional impedances <1 kΩ, and high-temperature frequency turnover points >90 °C in the VHF range, and are fabricated using a wafer-level-packaged HARPSS process. Packaged devices show excellent robustness against temperature cycling, device thinning, and aging effects, which makes them a great candidate for stable high frequency references in size-sensitive and power-sensitive 5 G and other IoT applications.
Dysfunction of ventral tegmental area GABA neurons causes mania-like behavior
Authors: Yu Xiao , Ba Wei , Zhao Guangchao , Ma Ying , Harding Edward C. , Yin Lu , Wang Dan , Li Huiming , Zhang Peng , Shi Youran , Yustos Raquel , Vyssotski Alexei L. , Dong Hailong , Franks Nicholas P. , Wisden William
Published: June 2020

The ventral tegmental area (VTA), an important source of dopamine, regulates goal- and reward-directed and social behaviors, wakefulness, and sleep. Hyperactivation of dopamine neurons generates behavioral pathologies. But any roles of non-dopamine VTA neurons in psychiatric illness have been little explored. Lesioning or chemogenetically inhibiting VTA GABAergic (VTAVgat) neurons generated persistent wakefulness with mania-like qualities: locomotor activity was increased; sensitivity to D-amphetamine was heightened; immobility times decreased on the tail suspension and forced swim tests; and sucrose preference increased. Furthermore, after sleep deprivation, mice with lesioned VTAVgat neurons did not catch up on lost sleep, even though they were starting from a sleep-deprived baseline, suggesting that sleep homeostasis was bypassed. The mania-like behaviors, including the sleep loss, were reversed by valproate, and re-emerged when treatment was stopped. Lithium salts and lamotrigine, however, had no effect. Low doses of diazepam partially reduced the hyperlocomotion and fully recovered the immobility time during tail suspension. The mania like-behaviors mostly depended on dopamine, because giving D1/D2/D3 receptor antagonists reduced these behaviors, but also partially on VTAVgat projections to the lateral hypothalamus (LH). Optically or chemogenetically inhibiting VTAVgat terminals in the LH elevated locomotion and decreased immobility time during the tail suspension and forced swimming tests. VTAVgat neurons help set an animal’s (and perhaps human’s) mental and physical activity levels. Inputs inhibiting VTAVgat neurons intensify wakefulness (increased activity, enhanced alertness and motivation), qualities useful for acute survival. In the extreme, however, decreased or failed inhibition from VTAVgat neurons produces mania-like qualities (hyperactivity, hedonia, decreased sleep).
Concurrent chemo-radiotherapy with proton therapy: reduced toxicity with comparable oncological outcomes vs photon chemo-radiotherapy
Authors: Baumann Brian C. , Hallahan Dennis E. , Michalski Jeff M. , Perez Carlos A. , Metz James M.
Published: June 2020

Concurrent chemo-radiotherapy is a commonly employed curative treatment approach for locally advanced cancers but is associated with considerable morbidity. Chemo-radiotherapy using proton therapy may be able to reduce side effects of treatment and improve efficacy, but this remains an area of controversy and data are relatively limited. We comment on recently published studies and discuss future directions for proton therapy.
Examining treatment responses of diagnostic marrow in murine xenografts to predict relapse in children with acute lymphoblastic leukaemia
Authors: Alruwetei Abdulmohsen M. , Bendak Katerina , Yadav Babasaheb D. , Carol Hernan , Evans Kathryn , Mayoh Chelsea , Sutton Rosemary , Marshall Glenn M. , Lock Richard B.
Published: June 2020

Background

While current chemotherapy has increased cure rates for children with acute lymphoblastic leukaemia (ALL), the largest number of relapsing patients are still stratified as medium risk (MR) at diagnosis (50–60%). This highlights an opportunity to develop improved relapse-prediction models for MR patients. We hypothesised that bone marrow from MR patients who eventually relapsed would regrow faster in a patient-derived xenograft (PDX) model after induction chemotherapy than samples from patients in long-term remission.

Methods

Diagnostic bone marrow aspirates from 30 paediatric MR-ALL patients (19 who relapsed, 11 who experienced remission) were inoculated into immune-deficient (NSG) mice and subsequently treated with either control or an induction-type regimen of vincristine, dexamethasone, and L-asparaginase (VXL). Engraftment was monitored by enumeration of the proportion of human CD45+ cells (%huCD45+) in the murine peripheral blood, and events were defined a priori as the time to reach 1% huCD45+, 25% huCD45+ (TT25%) or clinical manifestations of leukaemia (TTL).

Results

The TT25% value significantly predicted MR patient relapse. Mutational profiles of PDXs matched their tumours of origin, with a clonal shift towards relapse observed in one set of VXL-treated PDXs.

Conclusions

In conclusion, establishing PDXs at diagnosis and subsequently applying chemotherapy has the potential to improve relapse prediction in paediatric MR-ALL.
Contrasting DCIS and invasive breast cancer by subtype suggests basal-like DCIS as distinct lesions
Authors: Bergholtz Helga , Lien Tonje G. , Swanson David M. , Frigessi Arnoldo ,   Oslo Breast Cancer Research Consortium (OSBREAC), Bathen Tone F. , Borgen Elin , Børresen-Dale Anne Lise , Engebråten Olav , Garred Øystein , Geisler Jürgen , Geitvik Gry Aarum , Hartmann-Johnsen Olaf Johan , Hofvind Solveig , Kristensen Vessela N. , Langerød Anita , Lingjærde Ole Christian , Mælandsmo Gunhild Mari , Naume Bjørn , Russnes Hege , Sauer Torill , Schlichting Ellen , Skjerven Helle Kristine , Daidone Maria Grazia , Tost Jörg , Wärnberg Fredrik , Sørlie Therese
Published: June 2020

Ductal carcinoma in situ (DCIS) is a non-invasive type of breast cancer with highly variable potential of becoming invasive and affecting mortality. Currently, many patients with DCIS are overtreated due to the lack of specific biomarkers that distinguish low risk lesions from those with a higher risk of progression. In this study, we analyzed 57 pure DCIS and 313 invasive breast cancers (IBC) from different patients. Three levels of genomic data were obtained; gene expression, DNA methylation, and DNA copy number. We performed subtype stratified analyses and identified key differences between DCIS and IBC that suggest subtype specific progression. Prominent differences were found in tumors of the basal-like subtype: Basal-like DCIS were less proliferative and showed a higher degree of differentiation than basal-like IBC. Also, core basal tumors (characterized by high correlation to the basal-like centroid) were not identified amongst DCIS as opposed to IBC. At the copy number level, basal-like DCIS exhibited fewer copy number aberrations compared with basal-like IBC. An intriguing finding through analysis of the methylome was hypermethylation of multiple protocadherin genes in basal-like IBC compared with basal-like DCIS and normal tissue, possibly caused by long range epigenetic silencing. This points to silencing of cell adhesion-related genes specifically in IBC of the basal-like subtype. Our work confirms that subtype stratification is essential when studying progression from DCIS to IBC, and we provide evidence that basal-like DCIS show less aggressive characteristics and question the assumption that basal-like DCIS is a direct precursor of basal-like invasive breast cancer.
Multicellular 3D Neurovascular Unit Model for Assessing Hypoxia and Neuroinflammation Induced Blood-Brain Barrier Dysfunction
Authors: Nzou Goodwell , Wicks Robert T. , VanOstrand Nicole R. , Mekky Gehad A. , Seale Stephanie A. , EL-Taibany Aya , Wicks Elizabeth E. , Nechtman Carl M. , Marrotte Eric J. , Makani Vishruti S. , Murphy Sean V. , Seeds M. C. , Jackson John D. , Atala Anthony J.
Published: June 2020

The blood-brain barrier (BBB) is a dynamic component of the brain-vascular interface that maintains brain homeostasis and regulates solute permeability into brain tissue. The expression of tight junction proteins between adjacent endothelial cells and the presence of efflux proteins prevents entry of foreign substances into the brain parenchyma. BBB dysfunction, however, is evident in many neurological disorders including ischemic stroke, trauma, and chronic neurodegenerative diseases. Currently, major contributors to BBB dysfunction are not well understood. Here, we employed a multicellular 3D neurovascular unit organoid containing human brain microvascular endothelial cells, pericytes, astrocytes, microglia, oligodendrocytes and neurons to model the effects of hypoxia and neuroinflammation on BBB function. Organoids were cultured in hypoxic chamber with 0.1% O2 for 24 hours. Organoids cultured under this hypoxic condition showed increased permeability, pro-inflammatory cytokine production, and increased oxidative stress. The anti-inflammatory agents, secoisolariciresinol diglucoside and 2-arachidonoyl glycerol, demonstrated protection by reducing inflammatory cytokine levels in the organoids under hypoxic conditions. Through the assessment of a free radical scavenger and an anti-inflammatory endocannabinoid, we hereby report the utility of the model in drug development for drug candidates that may reduce the effects of ROS and inflammation under disease conditions. This 3D organoid model recapitulates characteristics of BBB dysfunction under hypoxic physiological conditions and when exposed to exogenous neuroinflammatory mediators and hence may have potential in disease modeling and therapeutic development.
Simultaneous label-free live imaging of cell nucleus and luminescent nanodiamonds
Authors: Gulka Michal , Salehi Hamideh , Varga Bela , Middendorp Elodie , Pall Orsolya , Raabova Helena , Cloitre Thierry , Cuisinier Frederic J. G. , Cigler Petr , Nesladek Milos , Gergely Csilla
Published: June 2020

In recent years, fluorescent nanodiamond (fND) particles containing nitrogen-vacancy (NV) centers gained recognition as an attractive probe for nanoscale cellular imaging and quantum sensing. For these applications, precise localization of fNDs inside of a living cell is essential. Here we propose such a method by simultaneous detection of the signal from the NV centers and the spectroscopic Raman signal from the cells to visualize the nucleus of living cells. However, we show that the commonly used Raman cell signal from the fingerprint region is not suitable for organelle imaging in this case. Therefore, we develop a method for nucleus visualization exploiting the region-specific shape of C-H stretching mode and further use k-means cluster analysis to chemically distinguish the vicinity of fNDs. Our technique enables, within a single scan, to detect fNDs, distinguish by chemical localization whether they have been internalized into cell and simultaneously visualize cell nucleus without any labeling or cell-fixation. We show for the first time spectral colocalization of unmodified high-pressure high-temperature fND probes with the cell nucleus. Our methodology can be, in principle, extended to any red- and near-infrared-luminescent cell-probes and is fully compatible with quantum sensing measurements in living cells.
Differential effects of high fat diet-induced obesity on oocyte mitochondrial functions in inbred and outbred mice
Authors: Marei Waleed F. A. , Smits Anouk , Mohey-Elsaeed Omnia , Pintelon Isabel , Ginneberge Daisy , Bols Peter E. J. , Moerloose Katrien , Leroy Jo L. M. R.
Published: June 2020

Maternal obesity can cause reduced oocyte quality and subfertility. Mitochondrial dysfunction plays a central role here, and most often inbred mouse models are used to study these pathways. We hypothesized that the mouse genetic background can influence the impact of high fat diet (HFD)-induced obesity on oocyte quality. We compared the inbred C57BL/6 (B6) and the outbred Swiss strains after feeding a HFD for 13w. HFD-mice had increased body weight gain, hypercholesterolemia, and increased oocyte lipid droplet (LD) accumulation in both strains. LD distribution was strain-dependent. In Swiss mouse oocytes, HFD significantly increased mitochondrial inner membrane potential (MMP), reactive oxygen species concentrations, mitochondrial ultrastructural abnormalities (by 46.4%), and endoplasmic reticulum (ER) swelling, and decreased mtDNA copy numbers compared with Swiss controls (P < 0.05). Surprisingly, B6-control oocytes exhibited signs of cellular stress compared to the Swiss controls (P < 0.05); upregulated gene expression of ER- and oxidative stress markers, high mitochondrial ultrastructural abnormalities (48.6%) and ER swelling. Consequently, the HFD impact on B6 oocyte quality was less obvious, with 9% higher mitochondrial abnormalities, and no additive effect on MMP and stress marks compared to B6 control (P > 0.1). Interestingly, mtDNA in B6-HFD oocytes was increased suggesting defective mitophagy. In conclusion, we show evidence that the genetic background or inbreeding can affect mitochondrial functions in oocytes and may influence the impact of HFD on oocyte quality. These results should create awareness when choosing and interpreting data obtained from different mouse models before extrapolating to human applications.
The effect of bacteriochlorophyll derivative WST-D and near infrared light on the molecular and fibrillar architecture of the corneal stroma
Authors: Hayes S. , Aldahlawi N. , Marcovich A. L. , Brekelmans J. , Goz A. , Scherz A. , Young R. D. , Bell J. S. , O’Brart D. P. , Nuijts R. M. M. A. , Meek K. M.
Published: June 2020

A cross-linking technique involving application of Bacteriochlorophyll Derivative WST-11 mixed with dextran (WST-D) to the epithelium-debrided cornea and illumination with Near Infrared (NIR), has been identified as a promising therapy for stiffening pathologically weakened corneas. To investigate its effect on corneal collagen architecture, x-ray scattering and electron microscopy data were collected from paired WST-D/NIR treated and untreated rabbit corneas. The treated eye received 2.5 mg/mL WST-D and was illuminated by a NIR diode laser (755 nm, 10 mW/cm2). An increase in corneal thickness (caused by corneal oedema) occurred at 1-day post-treatment but resolved in the majority of cases within 4 days. The epithelium was fully healed after 6–8 days. X-ray scattering revealed no difference in average collagen interfibrillar spacing, fibril diameter, D-periodicity or intermolecular spacing between treated and untreated specimens. Similarly, electron microscopy images of the anterior and posterior stroma in healed WST-D/NIR corneas and untreated controls revealed no obvious differences in collagen organisation or fibril diameter. As the size and organisation of stromal collagen is closely associated with the optical properties of the cornea, the absence of any large-scale changes following treatment confirms the potential of WST-D/NIR therapy as a means of safely stiffening the cornea.
Touching the social robot PARO reduces pain perception and salivary oxytocin levels
Authors: Geva Nirit , Uzefovsky Florina , Levy-Tzedek Shelly
Published: June 2020

Human-human social touch improves mood and alleviates pain. No studies have so far tested the effect of human-robot emotional touch on experimentally induced pain ratings, on mood and on oxytocin levels in healthy young adults. Here, we assessed the effect of touching the robot PARO on pain perception, on mood and on salivary oxytocin levels, in 83 young adults. We measured their perceived pain, happiness state, and salivary oxytocin. For the 63 participants in the PARO group, pain was assessed in three conditions: Baseline, Touch (touching PARO) and No-Touch (PARO present). The control group (20 participants) underwent the same measurements without ever encountering PARO. There was a decrease in pain ratings and in oxytocin levels and an increase in happiness ratings compared to baseline only in the PARO group. The Touch condition yielded a larger decrease in pain ratings compared to No-Touch. These effects correlated with the participants’ positive perceptions of the interaction with PARO. Participants with higher perceived ability to communicate with PARO experienced a greater hypoalgesic effect when touching PARO. We show that human-robot social touch is effective in reducing pain ratings, improving mood and - surprisingly - reducing salivary oxytocin levels in adults.
Tetrakis(4-aminophenyl) ethene-doped perylene microcrystals with strong electrochemiluminescence for biosensing applications
Authors: Zhong Xia , Jiang Ming-Hui , Lei Yan-Mei , Chai Ya-Qin , Yuan Ruo , Zhuo Ying
Published: June 2020

A facile and economic method for the inhibition of ACQ effect was developed by doping of non-planar moleculars ETTA into Pe MCs, which exhibited almost 10 times stronger ECL signal in aqueous phase compared to that of pure Pe MCs.
An efficient and facile strategy for trifluoromethylation and perfluoroalkylation of isoquinolines and heteroarenes
Authors: Pan Yang , Li Jiangtao , Li Zhefeng , Huang Feng , Ma Xiaofeng , Jiao Wei , Shao Huawu
Published: June 2020

An effective and regioselective strategy for trifluoromethylation and perfluoroalkylation of isoquinolines and heteroarenes was developed.
An NMR based phosphodiesterase assay
Authors: Akimoto Madoka , Yu Tianning , Moleschi Kody , Van Katherine , Anand Ganesh S. , Melacini Giuseppe
Published: June 2020

A phosphodiesterase (PDE) assay based on 1D1H NMR to monitor the hydrolysis of cyclic nucleotides directly, without requiring tags or the addition of exogenous reagents.
A close view of the organic linker in a MOF: structural insights from a combined 1H NMR relaxometry and computational investigation
Authors: Pizzanelli Silvia , Monti Susanna , Gordeeva Larisa G. , Solovyeva Marina V. , Freni Angelo , Forte Claudia
Published: June 2020

Fast Field Cycling NMR combined with ReaxFF MDs and the PAW/GIPAW approach is used to characterize the amine nitrogen EFG tensor and its dynamics.
A tool for deciphering the redox potential ranking of organic compounds: a case study of biomass-extracted quinones for sustainable energy
Authors: Lambert Fanny , Danten Yann , Gatti Carlo , Frayret Christine
Published: June 2020

Molecular modelling combined with electronic structure scrutinization may provide required insights for addressing challenges with respect to the identification of redox-active targets usable as sustainable electrodes.
Understanding the role of ionic flux on the polarity of the exposed surfaces of ZnO
Authors: Vijay Aditi , Mukhopadhyaya Aritra , Shrivastava Vipul , Bhardwaj Devanshi , Ganguli Ashok K. , Ali Md. Ehesan , Vaidya Sonalika
Published: June 2020

The role of ionic flux in controlling the polarity of the surfaces of ZnO was evaluated, both experimentally and theoretically.
From nano-seggregation to mesophases: probing the liquid structure of perfluoroalkylalkanes with 129Xe NMR spectroscopy
Authors: Morgado Pedro , Barras João , Filipe Eduardo J. M.
Published: June 2020

Xenon NMR spectra show that liquid semifluorinated alkanes self-organize forming nano-domains and detects formation of mesophases proving co-existence of distinct environments.
On the behaviour of structure-sensitive reactions on single atom and dilute alloy surfaces
Authors: Papanikolaou Konstantinos G. , Stamatakis Michail
Published: June 2020

Typically structure sensitive dissociation reactions exhibit reduced structure-sensitivity when taking place over low-index single atom alloy surfaces.
MnO2 nanoflowers grown on a polypropylene separator for use as both a barrier and an accelerator of polysulfides for high-performance Li–S batteries
Authors: Zuo Yinze , Yan Tao , Zhu Yuejin , Zhou Jian , Su Weiming , Shi Xingling , Tang Yuefeng , Chen Yanfeng
Published: June 2020

The separator modification has been considered to be the most effective approach to obtain high-stability lithium–sulfur batteries (LSBs).
Discovery of crystal structure–stability correlation in iridates for oxygen evolution electrocatalysis in acid
Authors: Song Chang Woo , Lim Jieun , Bae Hyung Bin , Chung Sung-Yoon
Published: June 2020

We provide general descriptions regarding the structure–stability correlations of iridium-based complex-oxide catalysts for oxygen evolution reaction in acid media.
Liquefied gas electrolytes for wide-temperature lithium metal batteries
Authors: Yang Yangyuchen , Yin Yijie , Davies Daniel M. , Zhang Minghao , Mayer Matthew , Zhang Yihui , Sablina Ekaterina S. , Wang Shen , Lee Jungwoo Z. , Borodin Oleg , Rustomji Cyrus S. , Meng Y. Shirley
Published: June 2020

Liquefied gas electrolytes with unique solvation structure enable high ionic conductivity in extended temperature ranges, supporting wide-temperature high-voltage lithium metal batteries.
Selenium deficiency causes immune damage by activating the DUSP1/NF-κB pathway and endoplasmic reticulum stress in chicken spleen
Authors: Yiming Zhang , Qingqing Liu , Hang Yin , Yahong Min , Shu Li
Published: June 2020

Selenium deficiency causes endoplasmic reticulum stress by affecting Ca2+ homeostasis and activates T lymphocyte differentiation via the DUSP1/NF-κB pathway. These factors together affect the immune response of the spleen and cause tissue damage.
Synthesis, characterization and electroluminescence studies of cyanopyridine-based π-conjugative polymers carrying benzo[c][1,2,5]thiadiazole and naphtho[1,2-c:5,6-c′]bis([1,2,5]thiadiazole) units
Authors: Pilicode Naveenchandra , Naik Praveen , Acharya Madhukara , Adhikari Airody Vasudeva
Published: June 2020

Four new cyanopyridine based polymers, i.e.TDPy1-4 were designed, synthesized and well-characterized. The detailed studies reveal that the polymers own all the prerequisites required for the PLED application as active green light emitters.
Partial sodiation induced laminate structure and high cycling stability of black phosphorous for sodium-ion batteries
Authors: Zhuang Xiaoqiang , Li Kaikai , Zhang Tong-Yi
Published: June 2020

Partial sodiation induces the formation of alternating layered and amorphous lamellas in black phosphorus.
Multiferroic decorated Fe2O3 monolayer predicted from first principles
Authors: Shang Jing , Li Chun , Tang Xiao , Du Aijun , Liao Ting , Gu Yuantong , Ma Yandong , Kou Liangzhi , Chen Changfeng
Published: June 2020

Insertion of Li can covert Fe2O3 layer as a multiferroics due to the Jahn–Teller distortion and d orbital splitting, which is promising for advanced device applications.
Selective C–H chalcogenation of thiazoles via thiazol-2-yl-phosphonium salts
Authors: Zi You , Wagner Konrad , Schömberg Fritz , Vilotijevic Ivan
Published: June 2020

Medicinally relevant substituted benzothiazoles and thiazoles are prepared under mild conditions by a regioselective C2–H chalcogenation via preparation of the phosphonium salt and the subsequent reaction with S- and Se-centered nucleophiles.
Rapid construction of the ABD tricyclic skeleton in meliacarpinin B from carvone enabled by an INOC strategy
Authors: Dong Changming , Qiao Tianjiao , Xie Yi , Zhang Xiao , Ao Junli , Liang Guangxin
Published: June 2020

A highly diastereoselective synthesis of the ABD skeleton of meliacarpinin B is presented.
Study of a recycling reaction system for catalytic transformation of biomass-based carbohydrates via acidic-polar biphasic conditions
Authors: Karnjanakom Surachai , Bayu Asep , Maneechakr Panya , Samart Chanatip , Kongparakul Suwadee , Guan Guoqing
Published: June 2020

Ethyl levulinate was easily produced via one-pot conversion of sucrose under a reusable biphasic system over an active/stable acid catalyst.
Pragmatic and Conversational Features of Arabic-Speaking Adolescents With Autism Spectrum Disorder: Examining Performance and Caregivers' Perceptions
Authors: Almehmadi Wesam , Tenbrink Thora , Sanoudaki Eirini
Published: June 2020

Purpose

This study investigates the features of pragmatic and conversational skills in the language of Arabic-speaking adolescents with autism spectrum disorder (ASD) by comparing them with typically developing (TD) Arabic-speaking adolescents in Saudi Arabia. It aims to identify the differences in the pragmatic skills of the two groups and the perception of those skills by caregivers, with respect to four main pragmatic areas: discourse management, communicative function, conversational repair, and presupposition abilities.

Method

Data for this study were collected from 15 Saudi adolescents with ASD and a control group of 15 TD adolescents, matched for gender and language abilities. All the participants were in the normal IQ range. The caregivers of the adolescents with ASD and TD adolescents also participated in this study. Data were collected on the adolescents' performances using the Yale in vivo Pragmatic Protocol. In addition, the Pragmatics Profile of Everyday Communication Skills (PPECS) was used to collect data on the caregivers' perceptions of the adolescents' abilities. The combination of tools in this study allows for a unique comparison between actual performance and caregivers' perceptions.

Results

As expected, both the adolescents' performances and the caregivers' perceptions reflected an overall deficit in the pragmatic and conversational skills of adolescents with ASD. However, we also identified an inconsistency between the caregivers' estimation of the participant's pragmatic abilities and the actual abilities demonstrated by the adolescents. In particular, TD adolescents performed significantly better than adolescents with ASD in the pragmatic areas of turn-taking, topic maintenance, and topic initiation, but the caregivers did not detect differences between the two groups in these discourse management abilities.

Conclusions

This study has important implications for both ASD interventions and assessment. It provides a comprehensive assessment approach for measuring pragmatic skills, including both direct (participants' performances) and indirect (caregivers' perceptions) measures. Future research may benefit from adopting the combined approach used in this study to explore pragmatics in ASD. Differences between caregivers' perceptions and the performances of individuals with ASD should be considered, as well as the influence of various factors on their communication.
The Relationship Between Word Learning and Executive Function in Preschoolers With and Without Developmental Language Disorder
Authors: Kapa Leah L. , Erikson Jessie A.
Published: June 2020

Purpose

The purpose of this study was to examine the relationship between executive functioning and word learning among preschoolers with and without developmental language disorder (DLD).

Method

Forty-one preschool-age children with DLD were matched to typically developing children on age and sex. Participants were exposed to 10 novel pseudowords, half of which referred to familiar objects and half of which referred to unfamiliar objects. Their ability to produce, recognize, and comprehend the novel words was tested, and they completed executive function tasks measuring sustained selective attention, short-term memory, working memory, inhibition, and shifting.

Results

Preschoolers with DLD performed worse compared to typically developing peers on all measures of executive function and novel word learning. Both groups showed a relative weakness in producing pseudowords that corresponded with familiar objects versus pseudowords for unknown objects. Executive function accounted for statistically significant variance in word learning beyond group membership, with inhibition as a significant predictor of all word learning outcomes and short-term memory as a significant predictor of novel word comprehension. Executive function explained significant variance in novel word production and recognition even after accounting for variance explained by group differences in IQ and receptive vocabulary.

Conclusion

Findings replicate previous research reporting deficits in word learning and executive function in children with DLD, indicate that preschoolers are disadvantaged in learning new words for familiar objects, and support a relationship between executive function and word learning for children with and without DLD. Future research should examine the directionality of the relationship between these variables.
Circular regression models of modern harmonic producing sources
Authors: Babaev Stanislav , Singh Ravi Shankar , Cobben Sjef , Ćuk Vladimir , Desmet Jan
Published: June 2020

This study presents a novel measurement‐based method for modelling harmonic current injections of low‐voltage power electronics equipment. The aim of the developed methodology is to accurately represent harmonic current phase angle in response to the applied harmonic background voltage at the terminals of modelled device. In this method, the harmonic angles are analysed with the techniques of circular statistics. The performed study proves the adequacy of representing phase angles as sets of directional data rather than linear. After graphical and quantitative analysis, the regression models with underlying von Mises distribution are derived in the form of algebraic equation. This algebraic equation features sine and cosine terms and explains relationship between independent variable – voltage harmonic angle and dependent variable – current harmonic angle. The subsequent analysis of the residuals allows to conclude that models developed by applying this technique can be used in commercial simulation packages and allow to account on any value of background harmonic voltage angle.
Early anomaly detection and localisation in distribution network: a data‐driven approach
Authors: Shi Xin , Qiu Robert , He Xing , Ling Zenan , Yang Haosen , Chu Lei
Published: June 2020

The measurement data collected from the supervisory control and data acquisition (SCADA) system installed in distribution network can reflect the operational state of the network effectively. In this study, a random matrix theory‐based approach is developed for early anomaly detection and localisation by using the data. For every feeder in the distribution network, a corresponding data matrix is formed. Based on the Marchenko–Pastur law for the empirical spectral analysis of covariance ‘signal+noise’ matrix, the linear eigenvalue statistics are introduced to indicate the anomaly, and the outliers and their corresponding eigenvectors are analysed for locating the anomaly. As for the low observability feeders in the distribution network, an increasing data dimension algorithm is designed for the formulated low‐dimensional matrices being more accurately analysed. The developed approach can detect and localise the anomaly at an early stage, and it is robust to random disturbance and measurement error. Cases on Matpower simulation data and real SCADA data corroborate the feasibility of the approach.
Advanced bidding strategy for participation of energy storage systems in joint energy and flexible ramping product market
Authors: Khoshjahan Mohammad , Moeini‐Aghtaie Moein , Fotuhi‐Firuzabad Mahmud , Dehghanian Payman , Mazaheri Hesam
Published: June 2020

Recently, power system operators have initiated procurement of a new service in electricity markets named flexible ramping product (FRP). With the main goal of enhancing the grid flexibility, this product can provide a remarkable opportunity for an enhanced short‐term profitability. Energy storage systems (ESSs) with high ramping capability can leverage their profitability when properly participating in this market. This study introduces a stochastic optimisation framework for participation of ESSs in the FRP market. The proposed model formulates the optimal bidding strategy of ESSs considering the real‐time energy, flexible ramp‐up and ramp‐down marginal price signals and the associated uncertainties. In addition, as the market participants cannot directly submit bids for the FRP, the corresponding energy bidding adjustments required to award the proper FRP amounts are elaborated. The mathematical model is linearised and its application in real‐time market is investigated. The proposed framework is numerically analysed through which its effectiveness on enhancing the ESS profitability in the real‐time electricity markets is verified.
Quantifying flexibility of load aggregations: impact of communication constraints on reserve capacity
Authors: Herre Lars , Kazemi Syavash , Söder Lennart
Published: June 2020

Due to the increased use of variable renewable energy sources, more capacity for reserves is required. Non‐generating resources such as thermostatically controlled loads (TCLs) can arbitrage energy prices and provide reserves due to their thermal energy storage capacity. The quantity of reserves depends not only on the aggregate power capacity, but also on information and communication technology, exogenous parameters, and system operator requirements. Specifically, the practical limitations origin from (i) communication constraints, (ii) ambient temperature, and (iii) the dispatch time of the activation signal. This study explores the impact of these parameters on the amount of reserves that an aggregator of TCLs can provide to the system operator based on centralised control of a TCL population. A decision support tool is proposed that can be used by aggregators to decide on maximum dispatchable reserve bids. The method can accommodate the specific control algorithm and TCL population of an aggregator and is based on offline computation. It constitutes a powerful reserve bid library to be used when optimisation tools become computationally intractable due to the increased number of decentralised flexible loads.
Intersection traffic signal optimisation considering the impact of upstream curbside bus stops
Authors: Li Rui , Zheng Changjiang , Wang Hua , Zhao De , Ran Bin , Xue Xin
Published: June 2020

Transit‐oriented travel mode is considered as one of the most effective travel strategies for improving the level of travel service and reducing travel time and delay. Curbside bus stops are often built to support the operation of the transit system, which leads to new bottlenecks of road segments near such stops and exerts a negative impact on traffic flows of neighbouring intersections. The authors propose a traffic signal optimisation model with the objective to minimise total travel delay by considering the interaction of traffic flows between the intersections and upstream curbside bus stops. First, transits’ following and lane‐changing behaviours are explored by analysing their trajectories collected by unmanned vehicle aerial video detectors. Second, transits’ occupancy time at curbside bus stops is statistically analysed by using automatic vehicle location data. They then use an equivalent‐flow analysis method to quantify the impact caused by transits’ actions of lane‐changing and moving into/out stop basins (including the waiting process). Such impact is integrated into the algorithm of intersection traffic signal optimisation. They finally validate the proposed signal optimisation model based on real‐time traffic data collected from Nanjing, China. It is revealed that the improved model can reduce vehicle travel delay by 4.3% at the tested intersection.
The ALPINE-ALMA [CII] survey: Data processing, catalogs, and statistical source properties
Authors: Béthermin M. , Fudamoto Y. , Ginolfi M. , Loiacono F. , Khusanova Y. , Capak P. L. , Cassata P. , Faisst A. , Le Fèvre O. , Schaerer D. , Silverman J. D. , Yan L. , Amorin R. , Bardelli S. , Boquien M. , Cimatti A. , Davidzon I. , Dessauges-Zavadsky M. , Fujimoto S. , Gruppioni C. , Hathi N. P. , Ibar E. , Jones G. C. , Koekemoer A. M. , Lagache G. , Lemaux B. C. , Moreau C. , Oesch P. A. , Pozzi F. , Riechers D. A. , Talia M. , Toft S. , Vallini L. , Vergani D. , Zamorani G. , Zucca E.
Published: June 2020

The Atacama Large Millimeter Array (ALMA) Large Program to INvestigate [CII] at Early times (ALPINE) targets the [CII] 158 μm line and the far-infrared continuum in 118 spectroscopically confirmed star-forming galaxies between z = 4.4 and z = 5.9. It represents the first large [CII] statistical sample built in this redshift range. We present details regarding the data processing and the construction of the catalogs. We detected 23 of our targets in the continuum. To derive accurate infrared luminosities and obscured star formation rates (SFRs), we measured the conversion factor from the ALMA 158 μm rest-frame dust continuum luminosity to the total infrared luminosity (LIR) after constraining the dust spectral energy distribution by stacking a photometric sample similar to ALPINE in ancillary single-dish far-infrared data. We found that our continuum detections have a median LIR of 4.4 × 1011 L⊙. We also detected 57 additional continuum sources in our ALMA pointings. They are at a lower redshift than the ALPINE targets, with a mean photometric redshift of 2.5 ± 0.2. We measured the 850 μm number counts between 0.35 and 3.5 mJy, thus improving the current interferometric constraints in this flux density range. We found a slope break in the number counts around 3 mJy with a shallower slope below this value. More than 40% of the cosmic infrared background is emitted by sources brighter than 0.35 mJy. Finally, we detected the [CII] line in 75 of our targets. Their median [CII] luminosity is 4.8 × 108 L⊙ and their median full width at half maximum is 252 km s−1. After measuring the mean obscured SFR in various [CII] luminosity bins by stacking ALPINE continuum data, we find a good agreement between our data and the local and predicted SFR–L[CII] relations.
Predictions for the hydrogen-free ejecta of pulsational pair-instability supernovae
Authors: Renzo M. , Farmer R. , Justham S. , Götberg Y. , de Mink S. E. , Zapartas E. , Marchant P. , Smith N.
Published: June 2020

Present and upcoming time-domain astronomy efforts, in part driven by gravitational-wave follow-up campaigns, will unveil a variety of rare explosive transients in the sky. Here, we focus on pulsational pair-instability evolution, which can result in signatures that are observable with electromagnetic and gravitational waves. We simulated grids of bare helium stars to characterize the resulting black hole (BH) masses together with the ejecta composition, velocity, and thermal state. We find that the stars do not react “elastically” to the thermonuclear ignition in the core: there is not a one-to-one correspondence between pair-instability driven ignition and mass ejections, which causes ambiguity as to what is an observable pulse. In agreement with previous studies, we find that for initial helium core masses of 37.5 M⊙ ≲ MHe, init ≲ 41 M⊙, corresponding to carbon-oxygen core masses 27.5 M⊙ ≲ MCO ≲ 30.1 M⊙, the explosions are not strong enough to affect the surface. With increasing initial helium core mass, they become progressively stronger causing first large radial expansion (41 M⊙ ≲ MHe, init ≲ 42 M⊙, corresponding to 30.1 M⊙ ≲ MCO ≲ 30.8 M⊙) and, finally, also mass ejection episodes (for MHe, init ≳ 42 M⊙, or MCO ≳ 30.8 M⊙). The lowest mass helium core to be fully disrupted in a pair-instability supernova is MHe, init ≃ 80 M⊙, corresponding to MCO ≃ 55 M⊙. Models with MHe, init ≳ 200 M⊙ (MCO ≳ 114 M⊙) reach the photodisintegration regime, resulting in BHs with masses of MBH ≳ 125 M⊙. Although this is currently considered unlikely, if BHs from these models form via (weak) explosions, the previously-ejected material might be hit by the blast wave and convert kinetic energy into observable electromagnetic radiation. We characterize the hydrogen-free circumstellar material from the pulsational pair-instability of helium cores by simply assuming that the ejecta maintain a constant velocity after ejection. We find that our models produce helium-rich ejecta with mass of 10−3 M⊙ ≲ MCSM ≲ 40 M⊙, the larger values corresponding to the more massive progenitor stars. These ejecta are typically launched at a few thousand km s−1 and reach distances of ∼1012 − 1015 cm before the core-collapse of the star. The delays between mass ejection events and the final collapse span a wide and mass-dependent range (from subhour to 104 years), and the shells ejected can also collide with each other, powering supernova impostor events before the final core-collapse. The range of properties we find suggests a possible connection with (some) type Ibn supernovae.
Inferring the origins of the pulsed γ-ray emission from the Crab pulsar with ten-year Fermi-LAT data
Authors: Yeung Paul K. H.
Published: June 2020

Context. The Crab pulsar is a bright γ-ray source, which has been detected at photon energies up to ∼1 TeV. Its phase-averaged and phase-resolved γ-ray spectra below 10 GeV exhibit exponential cutoffs, while those above 10 GeV apparently follow simple power laws.

Aims. We re-visit the γ-ray properties of the Crab pulsar with ten-year Fermi Large Area Telescope (LAT) data in the range of 60 MeV–500 GeV. With the phase-resolved spectra, we investigate the origins and mechanisms responsible for the emissions.

Methods. The phaseograms were reconstructed for different energy bands and further analysed using a wavelet decomposition. The phase-resolved energy spectra were combined with the observations of ground-based instruments, such as MAGIC and VERITAS, to achieve a larger energy converage. We fitted power-law models to the overlapping energy spectra from 10 GeV to ∼1 TeV. In the fit, we included a relative cross-calibration of energy scales between air-shower-based gamma-ray telescopes with the orbital pair-production telescope from the Fermi mission.

Results. We confirm the energy-dependence of the γ-ray pulse shape and, equivalently, the phase-dependence of the spectral shape for the Crab pulsar. A relatively sharp cutoff at a relatively high energy of ∼8 GeV is observed for the bridge-phase emission. The E >  10 GeV spectrum observed for the second pulse peak is harder than those for other phases.

Conclusions. In view of the diversity of phase-resolved spectral shapes of the Crab pulsar, we tentatively propose a multi-origin scenario where the polar-cap, outer-gap, and relativistic-wind regions are involved.
High-precision abundances of elements in solar-type stars
Authors: Nissen P. E. , Christensen-Dalsgaard J. , Mosumgaard J. R. , Silva Aguirre V. , Spitoni E. , Verma K.
Published: June 2020

Aims. Previous high-precision studies of abundances of elements in solar twin stars are extended to a wider metallicity range to see how the trends of element ratios with stellar age depend on [Fe/H].

Methods. HARPS spectra with signal-to-noise ratios S/N ≳ 600 at λ​ ∼ ​6000 Å were analysed with MARCS model atmospheres to obtain 1D LTE abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Sr, and Y for 72 nearby solar-type stars with metallicities in the range of −0.3 ≲ [Fe/H] ≲ +0.3 and ASTEC stellar models were used to determine stellar ages from effective temperatures, luminosities obtained via Gaia DR2 parallaxes, and heavy element abundances.

Results. The age-metallicity distribution appears to consist of the following two distinct populations: a sequence of old stars with a steep rise of [Fe/H] to ∼​ + 0.3 dex at an age of ∼​7 Gyr and a younger sequence with [Fe/H] increasing from about −0.3 dex to ∼​ + 0.2 dex over the last 6 Gyr. Furthermore, the trends of several abundance ratios, [O/Fe], [Na/Fe], [Ca/Fe], and [Ni/Fe], as a function of stellar age, split into two corresponding sequences. The [Y/Mg]-age relation, on the other hand, shows no offset between the two age sequences and has no significant dependence on [Fe/H], but the components of a visual binary star, ζ Reticuli, have a large and puzzling deviation.

Conclusions. The split of the age-metallicity distribution into two sequences may be interpreted as evidence of two episodes of accretion of gas onto the Galactic disk with a quenching of star formation in between. Some of the [X/Fe]-age relations support this scenario but other relations are not so easy to explain, which calls for a deeper study of systematic errors in the derived abundances as a function of [Fe/H], in particular 3D non-LTE effects.