bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of bit-rock interface temperature and wear rate of the tungsten carbide drill bit during rotary drilling
Authors: Shankar Vijay Kumar , Kunar Bijay Mihir , Murthy Chivukula Suryanarayana , Ramesh M. R. 
Published: April 2020

AbstractRock drilling is an essential operation in mining industries. Temperature at the bit-rock interface plays a major role in the wear rate of the drill bit. This paper primarily focuses on the wear rate of tungsten carbide (WC) drill bit and the interrelationship between temperature and wear rate during rotary drilling operations conducted using a computer numerical control (CNC) machine. The interrelationship between the temperature and wear rate was studied with regard to three types of rock samples, i.e., fine-grained sandstone (FG) of uniaxial compressive strength (UCS) that is 17.83 MPa, medium-grained sandstone (MG) of UCS that is 13.70 MPa, and fine-grained sandstone pink (FGP) of UCS that is 51.67 MPa. Wear rate of the drill bit has been measured using controlled parameters, i.e., drill bit diameter (6, 8, 10, 12, and 16 mm), spindle speed (250, 300, 350, 400, and 450 rpm), and penetration rate (2, 4, 6, 8, and 10 mm/min), respectively. Further, a fully instrumented laboratory drilling set-up was utilized. The weight of each bit was measured after the bit reached 30 mm depth in each type of the rock sample. Furthermore, effects of the bit-rock interface temperature and operational parameters on wear rate of the drill bits were examined. The results show that the wear rate of drill bits increased with an increase in temperature for all the bit-rock combinations considered. This is due to the silica content of the rock sample, which leads to an increase in the frictional heat between the bit-rock interfaces. However, in case of medium-grained sandstone, the weight percentage (wt%) of SiO2 is around 7.23 wt%, which presents a very low wear rate coefficient of 6.33×10−2 mg/(N·m). Moreover, the temperature rise during drilling is also minimum, i.e., around 74 °C, in comparison to that of fine-grained sandstone and fine-grained sandstone pink. In addition, this paper develops the relationship between temperature and wear rate characteristics by employing simple linear regression analysis.
Preparation, characterization, and tribological properties of silica-nanoparticle-reinforced B-N-co-doped reduced graphene oxide as a multifunctional additive for enhanced lubrication
Authors: Xiong Sang , Zhang Baosen , Luo Shuai , Wu Hao , Zhang Zhen 
Published: April 2020

AbstractMicrowave-synthesized SiO2-reinforced B-N-co-doped reduced graphene oxide (SiO2-B-N-GO) nanocomposites were characterized by X-ray photon spectroscopy (XPS), X-ray diffraction (XRD), infrared (IR) spectroscopy, and transmission electron microscopy/energy dispersive X-ray (TEM/EDX) analysis. The tribological properties of the SiO2-B-N-GO prepared as anti-wear additives for enhanced lubrication were studied using a four-ball tester. The experiment results indicated that SiO2-B-N-GO exhibits excellent load-carrying, anti-wear, and anti-friction properties in a base oil, especially at the optimal concentration of additives at 0.15 wt%. The wear scar diameter decreased from 0.70 to 0.37 mm and the coefficient of friction was reduced from 0.092 to 0.070, which reductions are attributed to the formation of B-N and graphene layer tribofilms of several tens of nanometers in thickness that prevented direct contact between metals.
Negative weights in network time model
Authors: Vattai Zoltán A. , Mályusz Levente 
Published: April 2020

AbstractTime does not go backward. A negative duration, such as “time period” at first sight is difficult to interpret. Previous network techniques (CPM/PERT/PDM) did not support negative parameters and/or loops (potentially necessitating recursive calculations) in the model because of the limited computing and data storage capabilities of early computers. Monsieur Roy and John Fondahl implicitly introduced negative weights into network techniques to represent activities with fixed or estimated durations (MPM/PDM). Subsequently, the introduction of negative lead and/or lag times by software developers (IBM) apparently overcome the limitation of not allowing negative time parameters in time model. Referring to general digraph (Event on Node) representation where activities are represented by pairs of nodes and pairwise relative time restrictions are represented by weighted arrows, we can release most restraints in constructing the graph structure (incorporating the dynamic model of the inner logic of time plan), and a surprisingly flexible and handy network model can be developed that provides all the advantages of the abovementioned techniques. This paper aims to review the theoretical possibilities and technical interpretations (and use) of negative weights in network time models and discuss approximately 20 types of time-based restrictions among the activities of construction projects. We focus on pure relative time models, without considering other restrictions (such as calendar data, time-cost trade-off, resource allocation or other constraints).
Word Replaceability Through Word Vectors
Authors: Taraba Peter 
Published: April 2020

AbstractThere have been many numerical methods developed recently that try to capture the semantic meaning of words through word vectors. In this study, we present a new way to learn word vectors using only word co-appearances and their average distances. However, instead of claiming semantic or syntactic word representation, we lower our assertions and claim only that we learn word vectors, which express word’s replaceability in sentences based on their Euclidean distances. Synonyms are a subgroup of words which can replace each other, and we will use them to show differences between training on words that appear close to each other in a local window and training that uses distances between words, which we use in this study. Using ConceptNet 5.5.0’s synonyms, we show that word vectors trained on word distances create higher contrast in distributions of word similarities than was done with Glove, where only word appearances close to each other were engaged. We introduce a measure, which looks at intersection of histograms of word distances for synonyms and non-synonyms.
Short-term associations between Legionnaires' disease incidence and meteorological variables in Belgium, 2011–2019
Authors: Braeye T. , Echahidi F. , Meghraoui A. , Laisnez V. , Hens N. 
Published: April 2020

AbstractThe number of reported cases with Legionnaires' disease (LD) is increasing in Belgium. Previous studies have investigated the associations between LD incidence and meteorological factors, but the Belgian data remained unexplored. We investigated data collected between 2011 and 2019. Daily exposure data on temperature, relative humidity, precipitation and wind speed was obtained from the Royal Meteorological Institute for 29 weather stations. Case data were collected from the national reference centre and through mandatory notification. Daily case and exposure data were aggregated by province. We conducted a time-stratified case-crossover study. The ‘at risk’ period was defined as 10 to 2 days prior to disease onset. The corresponding days in the other study years were selected as referents. We fitted separate conditional Poisson models for each day in the ‘at risk’ period and a distributed lag non-linear model (DLNM) which fitted all data in one model. LD incidence showed a yearly peak in August and September. A total of 614 cases were included. Given seasonality, a sequence of precipitation, followed by high relative humidity and low wind speed showed a statistically significant association with the number of cases 6 to 4 days later. We discussed the advantages of DLNM in this context.
Eddies in the Hawaiian Archipelago Region: Formation, Characterization, and Potential Implications on Larval Retention of Reef Fish
Authors: Lindo‐Atichati David , Jia Yanli , Wren Johanna L. K. , Antoniades Andreas , Kobayashi Donald R. 
Published: April 2020

AbstractHere we present an assessment of eddy activity in a 3,500 × 2,000 km region of the North Pacific. Eddies were identified and tracked within a numerical simulation that used the Massachusetts Institute of Technology general circulation model and an eddy characterization algorithm. Spatially, eddy births were more frequent: (1) nearshore (cyclones) and offshore (anticyclones) on the windward side of the main Hawai‘ian Islands; (2) in patches of cyclones and anticyclones that resembled the dipole structure of wind stress curl along the islands’ leeward side; and (3) in zonal patches of eddies of both polarities west and north of the islands. Temporally, high eddy activities occurred in spring. There was a meridional distribution of eddy lifespans, which increased northward. Cyclones were more abundant, longer‐lived, smaller, and more nonlinear. Reef fish spawning locations in Hawai‘i coincide with the regions of high eddy activity, with nonlinear eddies responsible for high larval retention.
Evidence for Adsorption of Chlorine Species on Iron (III) (Hydr)oxides in the Sheepbed Mudstone, Gale Crater, Mars
Authors: Peretyazhko T. S. , Ralston S. J. , Sutter B. , Ming D. W. 
Published: April 2020

AbstractAncient aquatic environments in Yellowknife Bay, Gale crater, Mars, could create favorable conditions for adsorption of chlorine compounds (perchlorate and chloride) on Fe (III) (hydr)oxides present in the Sheepbed mudstone, such as akaganeite and ferrihydrite. In this work, 5.2 mM ClO4− and 1.7 to 12 mM Cl− were adsorbed onto ferrihydrite and 5.2 mM ClO4− was adsorbed onto akaganeite at ultraacidic (pH 2–2.5), acidic (pH 3.8–4.5), and near‐neutral (pH 6.2–7.7) pH. Samples were characterized by evolved gas analysis and compared to the data collected for the Cumberland sample from the Sheepbed mudstone. Evolved gas analysis showed that ferrihydrite with 0.5–1 wt.% ClO4− adsorbed under ultraacidic and acidic conditions had a well‐resolved O2 peak at 306 °C due to the thermal decomposition of adsorbed ClO4−. All akaganeite samples with 0.5 wt.% adsorbed ClO4− had a weak peak at 312 °C tentatively assigned to decomposing perchlorate. Evolved gas analysis demonstrated that 0.5–2 wt.% Cl− adsorbed on ferrihydrite at ultraacidic and acidic pH was the main contributor to HCl evolved at >470 °C. Comparison with martian observations indicated that the temperature of the O2 peak originating from ClO4− adsorbed on ferrihydrite matched well with the thermal evolution of O2 from the Cumberland. Evolved HCl originating from Cl− adsorbed on ferrihydrite was within the temperature range of the high‐temperature HCl release from Cumberland (~770 °C). These observations suggest that ferrihydrite containing adsorbed ClO4− and Cl− could exist in the mudstone. Experimental results are consistent with adsorption at acidic pH < 4 environments through postdepositional water‐rock interactions of ferrihydrite with acid‐sulfate groundwater containing dissolved chloride and perchlorate.
Coral Records at the Northern Edge of the Western Pacific Warm Pool Reveal Multiple Drivers of Sea Surface Temperature, Salinity, and Rainfall Variability Since the End of the Little Ice Age
Authors: Ramos R. D. , Goodkin N. F. , Fan T.‐Y. 
Published: April 2020

AbstractReconstructions of key climate parameters prior to anthropogenic influences serve to constrain decadal to multicentury natural climate variability. In the western Pacific region, relatively few reconstructions exist north of the Western Pacific Warm Pool (WPWP), a region critical to global climate. In this study, we collected a coral core from Houbihu, southern Taiwan, and generated a 225‐year reconstruction of annual and wintertime sea surface temperature, dry season sea surface salinity, and wet season rainfall records derived from paired Porites Sr/Ca and δ18O profiles extending back to the end of the Little Ice Age (1850 CE). Multidecadal sea surface temperature trends generally track regional surface temperature reconstructions, indicating the dominant influence of solar and volcanic radiative forcings. Reconstructed dry season sea surface salinity reflects an advection signal linked to the East Asian Winter Monsoon and the Pacific Decadal Oscillation, both influencing variations in the Kuroshio Intrusion across the Luzon Strait. Reconstructed wet season rainfall, on the other hand, reveals influence of the Pacific Decadal Oscillation on the decadal variability of local and regional rainfall patterns. Relative to the late 1900s, our climate reconstructions document cooler and drier (high salinity and low rainfall) conditions during the end of the Little Ice Age, supporting other lines of evidence of a retracted WPWP region during this period. In the late 20th to early 21st century, our climate reconstructions record warming and freshening (low salinity and high rainfall) trends, highlighting the potential impact of anthropogenic forcing in the extension of the WPWP.
Flow Loss in Deltaic Distributaries: Impacts on Channel Hydraulics, Morphology, and Stability
Authors: Esposito C. R. , Georgiou I. Y. , Straub K. M. 
Published: April 2020

AbstractThe most comprehensive data sets documenting hydraulic and sediment transport regimes in the lower reaches of alluvial rivers come from systems that are managed to prevent flow loss from the channel into the overbank environment. Even moderate losses can have significant impacts on in‐channel velocity and sediment transport; therefore, a full understanding of flow loss and its effects is an important prerequisite to insights into channel function and to designing effective management strategies. We use the term flow loss for losses of water that are locally small relative to the main channel discharge. We present a unique data set documenting discharge, channel geometry, and water surface elevation from three distributary channel networks in the Mississippi River Delta where flow loss is widespread. We apply our data to validate a 1‐D hydraulic model, which then drives a previously validated model of sediment transport. Results from the modeling effort demonstrate that velocity and sediment transport trends are substantially modulated by flow loss in the ranges observed in distributary networks. The effect of flow loss on distributary channels established, we then examine how flood control infrastructure may have impacted the morphological evolution of the lowermost reaches of a large alluvial river like the Mississippi. The expected outcome of preventing flow loss is erosion in the channel's lowermost reach, in agreement with observational data. Finally, we develop a theoretical metric for a stable channel, and show that flow loss is a potentially important and understudied contributor to the long‐term behavior of distributary channels.
Surface Conduction Model for Fractal Porous Media
Authors: Wang Hongtao , Revil André 
Published: April 2020

AbstractThe electrical conductivity of natural water‐saturated porous materials has two contributions, one associated with conduction in the pore network and a second one associated with the electrical double layer coating the surface of the mineral grains, and called surface conductivity. We model the effect of material texture on surface conductivity based on fractal theory. We demonstrate that surface conductivity obeys a power‐law dependence (that we called surface Archie's law) on the specific surface area. The power exponent is theoretically related to the porosity exponent entering Archie's law and to the fractal dimension of the pore network. A permeability model is derived by combining the new surface Archie's law and the Kozeny‐Carman model. We show that our model is consistent with both numerical finite element simulations on synthetic porous media and experimental data.
Subseasonal Vacillations in the Winter Stratosphere
Authors: Hardiman S. C. , Scaife A. A. , Dunstone N. J. , Wang L. 
Published: April 2020

AbstractSimple models of wave‐mean flow interaction in the Northern Hemisphere winter stratosphere suggest the existence of subseasonal vacillations in the strength of the polar vortex. Here, we define a sinusoidal fit to the daily deseasonalized stratospheric wind. A suitable fixed period and amplitude for the sine waves is identified. Their mean value, equivalent to polar vortex strength, and phase, equivalent to the timing of sudden stratospheric warmings during winter, varies from year to year. These vacillations explain much of the subseasonal and interannual variability in the monthly mean vortex strength and, consistent with wave‐mean flow interaction theory, their amplitude correlates positively with the magnitude of winter mean planetary wave driving. Furthermore, they allow skillful prediction of the vortex strength one month ahead. Identifying and understanding this subseasonal variability has potential implications for winter seasonal forecasts, as the December–February mean behavior may miss important subseasonal events.
Neurogranin as a cognitive biomarker in cerebrospinal fluid and blood exosomes for Alzheimer’s disease and mild cognitive impairment
Authors: Liu Weilin , Lin Huawei , He Xiaojun , Chen Lewen , Dai Yaling , Jia Weiwei , Xue Xiehua , Tao Jing , Chen Lidian 
Published: April 2020

AbstractAlzheimer’s disease (AD) is a progressive neurodegenerative disorder with clinical, biological, and pathological features occurring along a continuum from normal to end-stage disease. Currently, the diagnosis of AD depends on clinical assessments and post-mortem neuropathology, which is unbenefited early diagnosis and progressive monitoring. In recent years, clinical studies have reported that the level of cerebrospinal fluid (CSF) and blood neurogranin (Ng) are closely related to the occurrence and subsequent progression of AD. Therefore, the study used meta-analysis to identify the CSF and blood Ng levels for the development of diagnosis biomarker of patients with AD and mild cognitive impairment (MCI). We searched the Pubmed, Embase, Cochrane Library, and Web of Science databases. A total of 24 articles eligible for inclusion and exclusion criteria were assessed, including 4661 individuals, consisting of 1518 AD patients, 1501 MCI patients, and 1642 healthy control subjects. The level of CSF Ng significantly increased in patients with AD and MCI compared with healthy control subjects (SMD: 0.84 [95% CI: 0.70–0.98], P < 0.001; SMD: 0.53 [95% CI: 0.40–0.66], P = 0.008), and higher in AD patients than in MCI patients (SMD: 0.18 [95% CI: 0.07–0.30], P = 0.002), and CSF Ng level of patients with MCI-AD who progressed from MCI to AD was significantly higher than that of patients with stable MCI (sMCI) (SMD: 0.71 [95% CI: 0.25–1.16], P = 0.002). Moreover, the concentration of Ng in blood plasma exosomes of patients with AD and MCI was lower than that of healthy control subjects (SMD: −6.657 [95% CI: −10.558 to −2.755], P = 0.001; and SMD: −3.64 [95% CI: −6.50 to −0.78], P = 0.013), and which in patients with AD and MCI-AD were also lower than those in patients with sMCI (P < 0.001). Furthermore, regression analysis showed a negative relationship between MMSE scores and CSF Ng levels in MCI patients (slope = −0.249 [95% CI: −0.003 to −0.495], P = 0.047). Therefore, the Ng levels increased in CSF, but decreased in blood plasma exosomes of patients with AD and MCI-AD, and highly associated with cognitive declines. These findings provide the clinical evidence that CSF and blood exosomes Ng can be used as a cognitive biomarker for AD and MCI-AD, and further studies are needed to define the specific range of Ng values for diagnosis at the different stages of AD.
Tet2-mediated epigenetic drive for astrocyte differentiation from embryonic neural stem cells
Authors: He Fei , Wu Hao , Zhou Liqiang , Lin Quan , Cheng Yin , Sun Yi E. 
Published: April 2020

AbstractDNA methylation and demethylation at CpG di-nucleotide sites plays important roles in cell fate specification of neural stem cells (NSCs). We have previously reported that DNA methyltransferases, Dnmt1and Dnmt3a, serve to suppress precocious astrocyte differentiation from NSCs via methylation of astroglial lineage genes. However, whether active DNA demethylase also participates in astrogliogenesis remains undetermined. In this study, we discovered that a Ten-eleven translocation (Tet) protein, Tet2, which was critically involved in active DNA demethylation through oxidation of 5-Methylcytosine (5mC), drove astrocyte differentiation from NSCs by demethylation of astroglial lineage genes including Gfap. Moreover, we found that an NSC-specific bHLH transcription factor Olig2 was an upstream inhibitor for Tet2 expression through direct association with the Tet2 promoter, and indirectly inhibited astrocyte differentiation. Our research not only revealed a brand-new function of Tet2 to promote NSC differentiation into astrocytes, but also a novel mechanism for Olig2 to inhibit astrocyte formation.
Regulation of sister chromatid cohesion by nuclear PD-L1
Authors: Yu Jia , Qin Bo , Moyer Ann M. , Nowsheen Somaira , Tu Xinyi , Dong Haidong , Boughey Judy C. , Goetz Matthew P. , Weinshilboum Richard , Lou Zhenkun , Wang Liewei 
Published: April 2020

AbstractProgrammed death ligand-1 (PD-L1 or B7-H1) is well known for its role in immune checkpoint regulation, but its function inside the tumor cells has rarely been explored. Here we report that nuclear PD-L1 is important for cancer cell sister chromatid cohesion. We found that depletion of PD-L1 suppresses cancer cell proliferation, colony formation in vitro, and tumor growth in vivo in immune-deficient NSG mice independent of its role in immune checkpoint. Specifically, PD-L1 functions as a subunit of the cohesin complex, and its deficiency leads to formation of multinucleated cells and causes a defect in sister chromatid cohesion. Mechanistically, PD-L1 compensates for the loss of Sororin, whose expression is suppressed in cancer cells overexpressing PD-L1. PD-L1 competes with Wing Apart-Like (WAPL) for binding to PDS5B, and secures proper sister chromatid cohesion and segregation. Our findings suggest an important role for nuclear PD-L1 in cancer cells independent of its function in immune checkpoint.
Taking stock of national climate policies to evaluate implementation of the Paris Agreement
Authors: Roelfsema Mark , van Soest Heleen L. , Harmsen Mathijs , van Vuuren Detlef P. , Bertram Christoph , den Elzen Michel , Höhne Niklas , Iacobuta Gabriela , Krey Volker , Kriegler Elmar , Luderer Gunnar , Riahi Keywan , Ueckerdt Falko , Després Jacques , Drouet Laurent , Emmerling Johannes , Frank Stefan , Fricko Oliver , Gidden Matthew , Humpenöder Florian , Huppmann Daniel , Fujimori Shinichiro , Fragkiadakis Kostas , Gi Keii , Keramidas Kimon , Köberle Alexandre C. , Aleluia Reis Lara , Rochedo Pedro , Schaeffer Roberto , Oshiro Ken , Vrontisi Zoi , Chen Wenying , Iyer Gokul C. , Edmonds Jae , Kannavou Maria , Jiang Kejun , Mathur Ritu , Safonov George , Vishwanathan Saritha Sudharmma 
Published: April 2020

AbstractMany countries have implemented national climate policies to accomplish pledged Nationally Determined Contributions and to contribute to the temperature objectives of the Paris Agreement on climate change. In 2023, the global stocktake will assess the combined effort of countries. Here, based on a public policy database and a multi-model scenario analysis, we show that implementation of current policies leaves a median emission gap of 22.4 to 28.2 GtCO2eq by 2030 with the optimal pathways to implement the well below 2 °C and 1.5 °C Paris goals. If Nationally Determined Contributions would be fully implemented, this gap would be reduced by a third. Interestingly, the countries evaluated were found to not achieve their pledged contributions with implemented policies (implementation gap), or to have an ambition gap with optimal pathways towards well below 2 °C. This shows that all countries would need to accelerate the implementation of policies for renewable technologies, while efficiency improvements are especially important in emerging countries and fossil-fuel-dependent countries.