COVIDSenti: A Large-Scale Benchmark Twitter Data Set for COVID-19 Sentiment Analysis.

Social media (and the world at large) have been awash with news of the COVID-19 pandemic. With the passage of time, news and awareness about COVID-19 spread like the pandemic itself, with an explosion of messages, updates, videos, and posts. Mass hysteria manifest as another concern in addition to the health risk that COVID-19 presented. Predictably, public panic soon followed, mostly due to misconceptions, a lack of information, or sometimes outright misinformation about COVID-19 and its impacts. It is thus timely and important to conduct an ex post facto assessment of the early information flows during the pandemic on social media, as well as a case study of evolving public opinion on social media which is of general interest. This study aims to inform policy that can be applied to social media platforms; for example, determining what degree of moderation is necessary to curtail misinformation on social media. This study also analyzes views concerning COVID-19 by focusing on people who interact and share social media on Twitter. As a platform for our experiments, we present a new large-scale sentiment data set COVIDSENTI, which consists of 90 000 COVID-19-related tweets collected in the early stages of the pandemic, from February to March 2020. The tweets have been labeled into positive, negative, and neutral sentiment classes. We analyzed the collected tweets for sentiment classification using different sets of features and classifiers. Negative opinion played an important role in conditioning public sentiment, for instance, we observed that people favored lockdown earlier in the pandemic; however, as expected, sentiment shifted by mid-March. Our study supports the view that there is a need to develop a proactive and agile public health presence to combat the spread of negative sentiment on social media following a pandemic.

Casein as a Modifier of Whey Protein Isolate Gel: Sensory Texture and Rheological Properties.

The objective of this study was to determine if casein could be used to adjust the structure of whey protein gels and alter targeted textural properties. Secondarily, we sought to determine if specific structural and mechanical properties were associated with sensory texture terms. Heat set gels were made from whey proteins alone or combined with casein in micellar or dispersed form at pH 6.0 and 5.5. Replacing the whey protein with casein produced a gel breakdown pattern that was more cohesive during mastication with increased moisture retention. Additionally, casein addition reduced gel strength but minimally altered recoverable energy (an indicator of elasticity). Structural breakdown patterns were shifted from brittle- to ductile-like fracture for gels containing dispersed casein at pH 5.5 or micellar casein at pH 6.0. Shifts in microstructure observed by confocal microscopy could not explain the changes in mechanical or sensory textures. The differentiating sensory attributes among treatments were adhesiveness, cohesiveness of mass, tackiness, firmness, fracturability, and deformability. Most notably, adding casein increased cohesiveness while maintaining water holding properties. Sensory texture properties could be explained by a combination of macroscopic structural changes (appearance), fracture properties, and postfracture breakdown pattern. Overall, it was demonstrated that casein can be used to alter whey protein gel structure such that sensory firmness and fracturability are decreased and cohesiveness is increased, while preventing a large increase in moisture release. PRACTICAL APPLICATION: There is a current desire to use alternative sources of protein in a variety of food applications, which requires the ability to design food structures with specific textural properties. Whey protein gels were used as a model soft solid structure with textural attributes of low cohesiveness and water release, and high firmness and fracturability. It was shown that adding casein modified the structure such that cohesiveness increased, firmness and fracturability decreased, and water holding ability was maintained. Using a second source of protein to modify a primary protein network appears to be a viable way to adjust textural properties.

Controlled growth of single-walled carbon nanotubes for unique nanodevices.

The controlled growth of bent and horizontally aligned single-walled carbon nanotubes (SWNTs) is demonstrated in this study. The bent SWNTs growth is attributed to the interaction between van der Waals force with substrate and aerodynamic force from gas flow. The curvature of bent SWNTs can be tailored by adjusting the angle between gas flow and step-edge direction. Electrical characterization shows that the one-dimensional resistivity of bent SWNTs is correlated with the curvature, which is due to strain induced energy bandgap variation. Additionally, a downshift of 10 cm(-1) in G-band is found at curved part by Raman analysis, which may be resulted from the bending induced carbon-carbon bond variation. In addition, horizontally aligned SWNTs and crossbar SWNTs were demonstrated. To prove the possibility of integrating the SWNTs having controllable morphology in carbon nanotube based electronics, an inverter with a gain of 2 was built on an individual horizontally aligned carbon nanotube.

The Health Service Bus: an architecture and case study in achieving interoperability in healthcare.

Interoperability in healthcare is a requirement for effective communication between entities, to ensure timely access to up to-date patient information and medical knowledge, and thus facilitate consistent patient care. An interoperability framework called the Health Service Bus (HSB), based on the Enterprise Service Bus (ESB) middleware software architecture is presented here as a solution to all three levels of interoperability as defined by the HL7 EHR Interoperability Work group in their definitive white paper "Coming to Terms". A prototype HSB system was implemented based on the Mule Open-Source ESB and is outlined and discussed, followed by a clinically-based example.

Polarized Rayleigh back-scattering from individual semiconductor nanowires.

A complete understanding of the interaction between electromagnetic radiation and semiconductor nanowires (NWs) is required in order to further develop a new generation of opto-electronic and photonic devices based on these nanosystems. The reduced dimensionality and high aspect ratio of nanofilaments can induce strong polarization dependence of the light absorption, emission and scattering, leading in some cases to the observation of optical antenna effects. In this work we present the first systematic study of polarized Rayleigh back-scattering from individual crystalline semiconductor NWs with known crystalline structure, orientation and diameters. To explain our experimental Rayleigh polar patterns, we propose a simple theory that relies on a secondary calculation of the volume-averaged internal electromagnetic fields inside the NW. These results revealed that the internal and emitted field can be enhanced depending on the polarization with respect to the NW axis; we also show that this effect strongly depends on the NW diameter.

Curvature-induced D-band Raman scattering in folded graphene.

Micro-Raman scattering from folds in single-layer graphene sheets finds a D-band at the fold for both incommensurate and commensurate folding, while the parent single-layer graphene lacks a D-band. A coupled elastic-continuum/tight-binding calculation suggests that this D-band arises from the spatially inhomogeneous curvature around a fold in a graphene sheet. The polarization dependence of the fold-induced D-band further reveals that the inhomogeneous curvature acts as a very smooth, ideal one-dimensional defect along the folding direction.

Cavity-enhanced stimulated raman scattering from short GaP nanowires.

We report the first observation of stimulated Raman scattering (SRS) from semiconductor nanowires (SNWs). Using continuous wave (CW) excitation (514.5 nm), very strong nonlinear SRS was observed in backscattering from short segments of crystalline GaP NWs with diameter d = 210 nm when the wire length L < 1.1 microm. The SRS intensity was found to increase dramatically with decreasing L down to 270 nm. The effective threshold pump power P(T) needed to observe the SRS is quite small. Indeed, we observe values of P(T) 3 orders of magnitude smaller than reported for bulk crystals of strongly nonlinear LiIO(3) and Ba(NO(3))(2) and 2 orders of magnitude smaller than that reported recently for SRS from "top-down" fabricated silicon microwaveguides. P(T) was observed to decrease linearly with decreasing L. Our data are discussed in terms of theoretical results developed for dielectric cavities. The quality factors Q for the short GaP cylindrical cavities studied here are estimated to be approximately 15,000. Our results suggest that SNWs may find applications as Raman lasers.

Adsorption of ammonia on graphene.

We report on experimental studies of NH3 adsorption/desorption on graphene surfaces. The study employs bottom-gated graphene field effect transistors supported on Si/SiO2 substrates. Detection of NH3 occurs through the shift of the source-drain resistance maximum ('Dirac peak') with the gate voltage. The observed shift of the Dirac peak toward negative gate voltages in response to NH3 exposure is consistent with a small charge transfer (f approximately 0.068 +/- 0.004 electrons per molecule at pristine sites) from NH3 to graphene. The desorption kinetics involves a very rapid loss of NH3 from the top surface and a much slower removal from the bottom surface at the interface with the SiO2 that we identify with a Fickian diffusion process.

Probing graphene edges via Raman scattering.

We present results of a Raman scattering study from the region near the edges of n-graphene layer films. We find that a Raman band (D) located near 1344 cm(-1) (514.5 nm excitation) originates from a region next to the edge with an apparent width of approximately 70 nm (upper bound). The D-band was found to exhibit five important characteristics: (1) a single Lorentzian component for n = 1, and four components for n = 2-4, (2) an intensity I(D) approximately cos(4) theta, where theta is the angle between the incident polarization and the average edge direction, (3) a local scattering efficiency (per unit area) comparable to the G-band, (4) dispersive behavior ( approximately 50 cm(-1)/eV for n = 1), consistent with the double resonance (DR) scattering mechanism, and (5) a scattering efficiency that is almost independent of the crystallographic orientation of the edge. High-resolution transmission electron microscope images reveal that our cleaved edges exhibit a sawtooth-like roughness of approximately 3 nm (i.e., approximately 20 times the C-C bond length). We propose that in the double resonance Raman scattering process the photoelectron scatters diffusely from our edges, obscuring the recently proposed strong variation in the scattering from armchair versus zigzag symmetry edges based on theoretical arguments.

A framework for semantic interoperability in healthcare: a service oriented architecture based on health informatics standards.

Healthcare information is composed of many types of varying and heterogeneous data. Semantic interoperability in healthcare is especially important when all these different types of data need to interact. Presented in this paper is a solution to interoperability in healthcare based on a standards-based middleware software architecture used in enterprise solutions. This architecture has been translated into the healthcare domain using a messaging and modeling standard which upholds the ideals of the Semantic Web (HL7 V3) combined with a well-known standard terminology of clinical terms (SNOMED CT).

Encapsulation of organic molecules in calcium phosphate nanocomposite particles for intracellular imaging and drug delivery.

Encapsulation of imaging agents and drugs in calcium phosphate nanoparticles (CPNPs) has potential as a nontoxic, bioresorbable vehicle for drug delivery to cells and tumors. The objectives of this study were to develop a calcium phosphate nanoparticle encapsulation system for organic dyes and therapeutic drugs so that advanced fluoresence methods could be used to assess the efficiency of drug delivery and possible mechanisms of nanoparticle bioabsorption. Highly concentrated CPNPs encapsulating a variety of organic fluorophores were successfully synthesized. Well-dispersed CPNPs encapsulating Cy3 amidite exhibited nearly a 5-fold increase in fluorescence quantum yield when compared to the free dye in PBS. FCS diffusion data and cell staining were used to show pH-dependent dissolution of the particles and cellular uptake, respectively. Furthermore, an experimental hydrophobic cell growth inhibitor, ceramide, was successfully delivered in vitro to human vascular smooth muscle cells via encapsulation in CPNPs. These studies demonstrate that CPNPs are effective carriers of dyes and drugs for bioimaging and, potentially, for therapeutic intervention.

n-Type behavior of graphene supported on Si/SiO(2) substrates.

Results are presented from an experimental and theoretical study of the electronic properties of back-gated graphene field effect transistors (FETs) on Si/SiO(2) substrates. The excess charge on the graphene was observed by sweeping the gate voltage to determine the charge neutrality point in the graphene. Devices exposed to laboratory environment for several days were always found to be initially p-type. After approximately 20 h at 200 degrees C in approximately 5 x 10(-7) Torr vacuum, the FET slowly evolved to n-type behavior with a final excess electron density on the graphene of approximately 4 x 10(12) e/cm(2). This value is in excellent agreement with our theoretical calculations on SiO(2), where we have used molecular dynamics to build the SiO(2) structure and then density functional theory to compute the electronic structure. The essential theoretical result is that the SiO(2) has a significant surface state density just below the conduction band edge that donates electrons to the graphene to balance the chemical potential at the interface. An electrostatic model for the FET is also presented that produces an expression for the gate bias dependence of the carrier density.

Near-infrared emitting fluorophore-doped calcium phosphate nanoparticles for in vivo imaging of human breast cancer.

Early detection is a crucial element for the timely diagnosis and successful treatment of all human cancers but is limited by the sensitivity of current imaging methodologies. We have synthesized and studied bioresorbable calcium phosphate nanoparticles (CPNPs) in which molecules of the near-infrared (NIR) emitting fluorophore, indocyanine green (ICG), are embedded. The ICG-CPNPs demonstrate exceptional colloidal and optical characteristics. Suspensions consisting of 16 nm average diameter particles are colloidally stable in physiological solutions (phosphate buffered 0.15 M saline (PBS), pH 7.4) with carboxylate or polyethylene glycol (PEG) surface functionality. ICG-doped CPNPs exhibit significantly greater intensity at the maximum emission wavelength relative to the free constituent fluorophore, consistent with the multiple molecules encapsulated per particle. The quantum efficiency per molecule of the ICG-CPNPs is 200% greater at 0.049 +/- 0.003 over the free fluorophore in PBS. Photostability based on fluorescence half-life of encapsulated ICG in PBS is 500% longer under typical clinical imaging conditions relative to the free dye. PEGylated ICG-CPNPs accumulate in solid, 5 mm diameter xenograft breast adenocarcinoma tumors via enhanced retention and permeability (EPR) within 24 h after systemic tail vein injection in a nude mouse model. Ex situ tissue imaging further verifies the facility of the ICG-CPNPs for deep-tissue imaging with NIR signals detectable from depths up to 3 cm in porcine muscle tissue. Our ex vivo and in vivo experiments verify the promise of the NIR CPNPs for diagnostic imaging in the early detection of solid tumors.

Toward the interoperability of HL7 v3 and SNOMED CT: a case study modeling mobile clinical treatment.

Semantic interoperability in healthcare can be achieved by a tighter coupling of terminology and HL7 message models. In this paper, we highlight the difficulty of achieving this goal, but show how it can become attainable by basing HL7 message models on SNOMED CT concepts and relationships. We then demonstrate how this methodology has been applied to a set of clinical observations for use in the ePOC project, and discuss our findings.

Monte Carlo simulation of intercalated carbon nanotubes.

Monte Carlo simulations of the single- and double-walled carbon nanotubes (CNT) intercalated with different metals have been carried out. The interrelation between the length of a CNT, the number and type of metal atoms has also been established. This research is aimed at studying intercalated systems based on CNTs and d-metals such as Fe and Co. Factors influencing the stability of these composites have been determined theoretically by the Monte Carlo method with the Tersoff potential. The modeling of CNTs intercalated with metals by the Monte Carlo method has proved that there is a correlation between the length of a CNT and the number of endo-atoms of specific type. Thus, in the case of a metallic CNT (9,0) with length 17 bands (3.60 nm), in contrast to Co atoms, Fe atoms are extruded out of the CNT if the number of atoms in the CNT is not less than eight. Thus, this paper shows that a CNT of a certain size can be intercalated with no more than eight Fe atoms. The systems investigated are stabilized by coordination of 3d-atoms close to the CNT wall with a radius-vector of (0.18-0.20) nm. Another characteristic feature is that, within the temperature range of (400-700) K, small systems exhibit ground-state stabilization which is not characteristic of the higher ones. The behavior of Fe and Co endo-atoms between the walls of a double-walled carbon nanotube (DW CNT) is explained by a dominating van der Waals interaction between the Co atoms themselves, which is not true for the Fe atoms.

Catalytic polymerization and facile grafting of poly(furfuryl alcohol) to single-wall carbon nanotube: preparation of nanocomposite carbon.

A nanocomposite carbon was prepared by grafting a carbonizable polymer, poly(furfuryl alcohol) (PFA), to a single-wall carbon nanotube (SWNT). The SWNT was first functionalized with arylsulfonic acid groups on the sidewall via a method using a diazonium reagent. Both Raman and FTIR spectroscopies were used to identify the functional groups on the nanotube surface. HRTEM imaging shows that the SWNT bundles are exfoliated after functionalization. Once this state of the SWNTs was accomplished, the PFA-functionalized SWNT (PFA-SWNT) was prepared by in situ polymerization of furfuryl alcohol (FA). The sulfonic acid groups on the surface of the SWNT acted as a catalyst for FA polymerization, and the resulting PFA then grafted to the SWNTs. The surfaces of the SWNTs converted from hydrophilic to hydrophobic when they were wrapped with PFA. The formation of the polymer and the attraction between it and the sulfonic acid groups were confirmed by IR spectra. A nanocomposite carbon was generated by heating the PFA-SWNT in argon at 600 degrees C, a process during which the PFA was transformed to nanoporous carbon (NPC) and the sulfonic acid groups were cleaved from the SWNT. Based upon the Raman spectra and HRTEM images of the composite, it is concluded that SWNTs survive this process and a continuous phase is formed between the NPC and the SWNT.