gebhart/patrepeval huggingface dataset:
A Substrate-Integrated and Scalable Templated Approach Based on Rusted Steel for the Fabrication of Polypyrrole Nanotube Arrays (2011)

We report here a facile, generalizable, and entirely scalable approach for the fabrication of vertically aligned arrays of Fe(2)O(3)/polypyrrole core-shell nanostructures and polypyrrole nanotubes. Our "all electrochemical" approach is based on the fabrication of α-Fe(2)O(3) nanowire arrays by the simple heat treatment of commodity low carbon steel substrates, followed by electropolymerization of conformal polypyrrole sheaths around the nanowires. Subsequently, electrochemical etching of the nanowires yields large-area vertically aligned polypyrrole nanotube arrays on the steel substrate. The developed methodology is generalizable to functionalized pyrrole monomers and represents a significant practical advance of relevance to the technological implementation of conjugated polymer nanostructures in electrochromics, electrochemical energy storage, and sensing.
Gaze-Aided Human-Computer and Human-Human Dialogue (2009)

Eye-gaze plays an important role in face-to-face communication. This chapter presents research on exploiting the rich information contained in human eye-gaze for two types of applications. The first is to enhance computer mediated human-human communication by overlaying eye-gaze movement onto the shared visual spatial discussion material such as a map. The second is to manage multimodal human-computer dialogue by tracking the user’s eye-gaze pattern as an indicator of user’s interest. The authors briefly review related literature and summarize results from two research projects on human-human and human-computer communication.
Computational Mechanistic Studies of Acid-Catalyzed Lignin Model Dimers for Lignin Depolymerization (2013)

Lignin is a heterogeneous alkyl-aromatic polymer that constitutes up to 30% of plant cell walls, and is used for water transport, structure, and defense. The highly irregular and heterogeneous structure of lignin presents a major obstacle in the development of strategies for its deconstruction and upgrading. Here we present mechanistic studies of the acid-catalyzed cleavage of lignin aryl-ether linkages, combining both experimental studies and quantum chemical calculations. Quantum mechanical calculations provide a detailed interpretation of reaction mechanisms including possible intermediates and transition states. Solvent effects on the hydrolysis reactions were incorporated through the use of a conductor-like polarizable continuum model (CPCM) and with cluster models including explicit water molecules in the first solvation shell. Reaction pathways were computed for four lignin model dimers including 2-phenoxy-phenylethanol (PPE), 1-(para-hydroxyphenyl)-2-phenoxy-ethanol (HPPE), 2-phenoxy-phenyl-1,3-propanediol (PPPD), and 1-(para-hydroxyphenyl)-2-phenoxy-1,3-propanediol (HPPPD). Lignin model dimers with a para-hydroxyphenyl ether (HPPE and HPPPD) show substantial differences in reactivity relative to the phenyl ether compound (PPE and PPPD) which have been clarified theoretically and experimentally. The significance of these results for acid deconstruction of lignin in plant cell walls will be discussed.
A Comparison of the Optical and Steric Tilt in Antiferroelectric Liquid Crystals (1999)

Abstract X-ray and optical techniques have been employed to study six materials that exhibit frustrated chiral smectic phases across the entire tilted phase range. The layer spacings are used to deduce the steric tilt angle of the systems which are compared with optical tilt of the phases. In general, the steric tilt is lower than the X-ray tilt, as would be expected. There is evidence of conformation driven inversion phenomena in three of the materials. The ratio of the tilts is strongly temperature dependent in all but two of the materials, and in three of the materials the x-ray tilt is higher than the optical tilt over part of the SmC*phase. The results are discussed in terms of molecular conformations.
Dishevelled genes mediate a conserved mammalian PCP pathway to regulate convergent extension during neurulation (2006)

The planar cell polarity (PCP) pathway is conserved throughout evolution, but it mediates distinct developmental processes. In Drosophila, members of the PCP pathway localize in a polarized fashion to specify the cellular polarity within the plane of the epithelium, perpendicular to the apicobasal axis of the cell. In Xenopus and zebrafish, several homologs of the components of the fly PCP pathway control convergent extension. We have shown previously that mammalian PCP homologs regulate both cell polarity and polarized extension in the cochlea in the mouse. Here we show, using mice with null mutations in two mammalian Dishevelled homologs, Dvl1 and Dvl2, that during neurulation a homologous mammalian PCP pathway regulates concomitant lengthening and narrowing of the neural plate, a morphogenetic process defined as convergent extension. Dvl2 genetically interacts with Loop-tail, a point mutation in the mammalian PCP gene Vangl2, during neurulation. By generating Dvl2 BAC (bacterial artificial chromosome) transgenes and introducing different domain deletions and a point mutation identical to the dsh1 allele in fly, we further demonstrated a high degree of conservation between Dvl function in mammalian convergent extension and the PCP pathway in fly. In the neuroepithelium of neurulating embryos, Dvl2 shows DEP domain-dependent membrane localization, a pre-requisite for its involvement in convergent extension. Intriguing, the Loop-tail mutation that disrupts both convergent extension in the neuroepithelium and PCP in the cochlea does not disrupt Dvl2 membrane distribution in the neuroepithelium, in contrast to its drastic effect on Dvl2 localization in the cochlea. These results are discussed in light of recent models on PCP and convergent extension.
Detecting elusive surface atoms with atomic force microscopy (2003)

In his famous 1959 speech titled “There is plenty of room at the bottom” (1), Nobel prize winning physicist Richard P. Feynman predicts that matter will be controlled and manipulated at the atomic scale in the foreseeable future. Furthermore, he proclaims that “it should be possible to see... individual atoms.” In many ways, Feynman's vision was realized with the invention of the scanning tunneling microscope (STM) by Gerd Binnig and Heinrich Rohrer in 1982, for which they were awarded the Nobel prize in physics (2). With the STM, quantum mechanical tunneling of electrons from a sharp metal tip to a conductive substrate is used to detect individual surface atoms with atomic resolution. The ability to “see” atoms in real space immediately solved many controversies in surface science including the complicated 7 × 7 reconstruction of the Si(111) surface (3).

One complication with the STM is that the tunneling current is a function of not only the surface topography but also the local electronic structure. On the graphite surface, there are two different types of carbon atoms in the basal plane, as distinguished by the presence (α) or absence (β) of a carbon atom in the plane immediately below the surface. Coupling of 2pz orbitals from α carbon atoms of adjacent layers lowers their bonding energies. Thus, the 2pz orbitals from β carbon atoms form the highest occupied (and lowest unoccupied) orbitals where the Fermi level crosses. These local electronic structure variations imply that the STM can only detect every other atom on the graphite surface. Consequently, an alternative imaging mechanism is required to detect the “hidden” α atoms on the graphite surface. The article by Hembacher et al. (4) in this issue of PNAS outlines a novel scanning probe microscope that solves the hidden atom problem. Their …
Dendritic cells and HIV-specific CD4+ T cells: HIV antigen presentation, T-cell activation, and viral transfer (2006)

Human immunodeficiency virus (HIV)-specific CD4+ lymphocytes are preferentially infected in HIV-positive individuals. To study this preferential infection, we have derived several HIV-specific (HS) CD4+ clones. We show that in dendritic cells (DCs), HIV virion capture led to major histocompatibility complex class-II (MHC-II)-restricted viral antigen presentation and to activation of HS cells. In contrast, neither cell-free virions nor infected lymphocytes activated HS cells. In DCs, the dendritic cell-specific intercellular adhesion molecule 3-grabbing nonintegrin (DC-SIGN/CD209), which internalizes virions, promoted MHC-II presentation of HIV antigens. Activation of HS cells by HIV-exposed DCs triggered an efficient viral spread in lymphocytes. CD4+ clones with irrelevant antigenic specificities were not activated by HIV-exposed DCs and poorly supported viral replication under this setting. Our results unravel the mechanisms of MHC-II-restricted HIV antigen presentation by DCs and describe how HIV gains access to the very cells designed by the immune system to counteract this pathogen.
Hyperleydigism: A Cause of Severe Pubertal Gynecomastia (1971)

A 14-yr-old boy developed spectacular gynecomastia in association with pubescent growth and rapid sexual maturation. Histologic examination of the testis disclosed plump active Leydig cells and accompanying spermatogenesis. Breast tissue was like that usually seen in gynecomastia and did not contain detectable quantities of the specific 8S estradiol binding protein and also failed to convert testosterone to dihydrotestosterone. The plasma concentration of testosterone was consistently above the range observed in normal men and other pubertal boys. The plasma estradiol concentration was proportionately elevated. Adrenocortical steroids were present in normal amounts. Plasma FSH and LH concentrations were also within the normal range. Testosterone and estradiol concentrations rose with chorionic gonadotropin therapy, but the testosterone level was not suppressed by treatment with prednisone or fluoxymesterone. It was concluded that the gynecomastia was the result of elevated levels of testicular sex hormones. This hyperleydigism was explained on the basis of a failure of the negative hypothalamic-pituitary feedback system to respond appropriately to circulating testosterone and estradiol.
Magnetic reversal of perpendicularly-biased Co/Pt multilayers (2002)

We have investigated the magnetic reversal behavior of $[(\mathrm{C}\mathrm{o}/\mathrm{P}\mathrm{t}{)}_{4}\mathrm{C}\mathrm{o}/\mathrm{C}\mathrm{o}\mathrm{O}{]}_{N}$ multilayers that are exchange biased perpendicular to the film plane. We find clear differences in the nucleation properties of the reverse domains of the ascending and descending branches of the hysteresis loops. However, the evolution of the reverse domains, once nucleated, is symmetric to positive and negative field sweeps. This behavior is in contrast to many in-plane biased experiments and can be understood from the collinear uniaxial magnetic anisotropy and unidirectional exchange-bias axis.
Pancreatic circulation: intrinsic regulation (1982)

The purpose of the present study was to characterize the intrinsic mechanisms involved in the regulation of blood flow and oxygenation in the totally isolated, perfused canine pancreas. Arterial pressure, venous outflow pressure, blood flow, arteriovenous oxygen difference, and capillary filtration coefficient were measured during graded arterial pressure reductions and venous pressure elevation. Reductions in arterial pressure caused pancreatic blood flow and vascular resistance to decrease, whereas venous pressure elevation resulted in a decreased blood flow and increased vascular resistance. The reductions in blood flow produced by arterial and venous pressure alterations were associated with increases in oxygen extraction and capillary filtration coefficient. During the same pressure perturbations, oxygen uptake remained constant between blood flows of 40-100 ml.min-1.100 g-1, yet decreased progressively as blood flow was reduced below 40 ml.min-1.100 g-1. Arterial occlusion resulted in a postocclusive reactive hyperemia, the magnitude of which was related to the duration of occlusion. The findings of this study suggest that intrinsic regulation of pancreatic blood flow can be attributed to both metabolic and myogenic mechanisms. Resistance and exchange vessels both appear to play a role in the regulation of oxygen delivery to the pancreatic parenchyma.
Direct deposition of a nanoporous palladium electrocatalyst for efficient hydrogen evolution reaction (2020)

The porous palladium directly deposited on metallic substrates by aerosol-assisted chemical vapor deposition exhibits remarkable HER performance in an acidic electrolyte.
Comparison of DFE and MLSE Receiver Performance on HF Channels (1985)

Data communication at rates near or above 2 kbits/s on 3 kHz-baadwidth HF radio channels is subject to impairment from severe linear dispersion, rapid channel time variation, and severe fading. In this investigation, recorded 2.4 kbit/s QPSK signals received from HF channels were processed to extract a time-varying estimate of the channel impulse response. From the estimated channel impulse responses, performance-related parameters were computed for ideal matched filter reception, maximum-likelihood sequence-estimation (MLSE), and decision feedback equalization (DFE). The results indicated that the simpler DFE receiver suffered only a small theoretical performance degradation relative to the more complex MLSE receiver. Other HF channel impulse response statistics were also obtained to shed light on equalization and filter adaptation techniques.
Efficient organometallic spin filter based on Europium-cyclooctatetraene wire (2009)

Electronic structures, magnetic, and transport properties of organometallic sandwich molecular wire (SMW) constructed with altering europium (Eu) atoms and cyclooctatetraene (COT) rings have been studied by spin-polarized first-principles calculations and nonequilibrium Green’s function method. The one-dimensional Eu-COT SMW is predicted to be a ferromagnetic semiconductor. The calculated average magnetic moment per Eu atom is about 7μB. The total magnetic moment (TMM) of Eun(COT)n+1(n=1–4) sandwich clusters increases linearly with the number of Eu atoms and the linear relation TMM=7n-2 holds, which agrees nicely with experimental observations. The spin transportation calculations show that Eu-COT clusters coupled to gold electrodes are nearly perfect spin filters. In addition, we find that this large transmission spin polarization is very robust regardless of the contact configuration of the junctions, which is very important for the future molecular spintronics.
Controlling the DNA Hybridization Chain Reaction (2020)

A novel method for controlling the oligomerization of metastable DNA hairpins using the hybridization chain reaction (HCR) is reported. Control was achieved through the introduction of a base-pair mismatch in the duplex of the hairpins. The mismatch modification allows one to kinetically differentiate initiation versus propagation events, leading to DNA oligomers up to 10 monomers long and improving dispersities from 2.5 to 1.3-1.6. Importantly, even after two consecutive chain extensions, dispersity remained unaffected, showing that well-defined block co-oligomers can be achieved. As a proof-of-concept, this technique was then applied to hairpin monomers functionalized with a mutant green fluorescent protein to prepare protein oligomers. Taken together, this work introduces an effective method for controlling living macromolecular HCR oligomerization in a manner analogous to the controlled polymerization of small molecules.
Stability, metallicity, and magnetism in niobium silicide nanofilms (2022)

Modern superconducting qubits based on two-dimensional (2D) transmons typically involve the growth of Nb thin films on high-resistivity Si substrates. Since imperfections at the Nb-Si heterointerface have been implicated as a source of two-level systems that limit quantum coherence times, detailed characterization and understanding of niobium silicide interfacial layers are critical to improving superconducting qubit technology. While bulk binary intermetallic niobium silicide phases are well understood, the thermodynamic phase stability and properties of ultrathin niobium silicides, such as those found at the Nb-Si heterointerface in 2D transmons, have not yet been explored. Here, we report finite-sized effects for ultrathin niobium silicide films using density functional theory calculations and predict nanoscale stabilization of ${\mathrm{Nb}}_{6}{\mathrm{Si}}_{5}$ over the bulk $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Nb}}_{5}{\mathrm{Si}}_{3}$ phase. This result is consistent with our experimental observations of a niobium silicide interfacial layer between a sputtered Nb thin film and the underlying Si substrate. Furthermore, our calculations show that ${\mathrm{Nb}}_{6}{\mathrm{Si}}_{5}$ nanofilms are nonmagnetic, making them superior to nanofilms of $\ensuremath{\alpha}\text{\ensuremath{-}}{\mathrm{Nb}}_{5}{\mathrm{Si}}_{3}$ that exhibit antiferromagnetic correlations detrimental to long coherence times in superconducting qubits. By providing atomic-scale insight into niobium silicide nanofilms, this paper can help guide ongoing efforts to optimize Nb-Si heterointerfaces for long coherence times in superconducting qubits.
Crowd-Sensing Road Surface Quality Using Connected Vehicle Data (2021)

This work presents an approach for collecting road surface data using connected vehicles. Road surface readings from multiple production vehicles were collected and aggregated to estimate road roughness measured by the International Roughness Index (IRI). The analysis compared multiple instances of connected vehicle data with high speed pavement profile vehicle (Class 1 profiler) data. A separate analysis compared multiple instances of connected vehicle data to an advanced walking profiler. Results demonstrate the feasibility of harvesting road surface data from the existing connected vehicles to support continuous road surface monitoring applications. Benefits include more timely acquisition of pavement data, broader coverage of the road network, and potential for aiding existing survey fleet in targeting early signs of pavement degradation. Collected roughness measurements were found to be closely aligned with reference devices that were employed as part of this study. A regional experiment in the Detroit Metropolitan area that covered 64 mi of roadways found that the connected vehicle data was highly correlated with Class 1 profiler data where 83% of traveled miles had a 0.8 or higher correlation. Moreover, 85% of the measurements had small absolute errors less than 50 in./mi and half of the measurements had absolute errors less than 20 in./mi. A test track experiment at Virginia Tech Transportation Institute Smart Road facility compared the connected vehicle data to the advanced walking profiler and showed that the correlations for repeatability and reproducibility are 0.90 and 0.91, respectively, which are very close to the standard requirement for certified profilers.
FABRICS II: A Statistically Based IC Fabrication Process Simulator (1984)

This paper describes FABRICS II, an IC fabriction process simulator which takes into account the statistical fluctuations inherent in the manufacturing process. FABRICS II is composed of two parts, a fabrication process simulator FAB1, and a semiconductor device simulator FAB2. The simulator produces model parameters of typical semiconductor devices manufactured in various fabrication processes (NMOS, CMOS, or bipolar). Possible applications of FABRICS II include verification and optimization of process and circuit design, yield prediction and maximization prior to IC fabrication, and IC failure analysis. Two examples which illustrate the application of FABRICS II are presented.
Space-time spreading and block coding for correlated fading channels in the presence of interference (2005)

We consider point-to-point wireless links with multiple antennas in the presence of interference. Channel spatial correlation and interference temporal covariance matrices are exploited to design multi-antenna transmitters. We develop a space-time spreading scheme that maximizes average signal to interference and noise ratio, and optimally power loaded space-time beam-forming (STBF) schemes that improve error probability performance. In order to increase transmission rates, we combine orthogonal space-time block coding with STBF and optimize power loading across beams. Our analytical and simulated results corroborate that STBF with optimal power loading can considerably reduce error probability.
Strain-Specific Serum Antibody Responses in Infants Undergoing Primary Infection with Respiratory Syncytial Virus (1988)

We sought to characterize the human respiratory syncytial virus (RSV) subgroup-specific antibody response to primary infection with RSV. RSV isolates from 43 infants and young children were typed as either subgroup A (Long strain-like) or B (18537 strain-like) based on reactivity with monoclonal antibodies. Acute-phase or preinfection and convalescent-phase sera were collected from the 43 subjects and tested in an enzyme-linked immunosorbent assay using purified F and G glycoproteins from RSV subgroups A and B and by neutralization assay against both subgroups of RSV. Twenty-six individuals had rises in titer of antibody to F glycoprotein, 27 to G glycoprotein, and 28 had rises in titer of neutralizing antibody. The antibody responses to homologous and heterologous F glycoproteins were not significantly different. In contrast, homologous vs. heterologous antibody responses to G glycoprotein were significantly different, with 7.3% relatedness between the G glycoproteins of subgroups A and B. Analysis of neutralizing antibody responses revealed 31% relatedness.
Reduced-Bandwidth MR Imaging of the Head at 1.5 T (1989)

A decrease in the magnetic resonance (MR) imaging bandwidth can be used to increase the signal-to-noise ratio (S/N) at constant imaging time or to maintain the S/N for reduction of imaging time. The effect of bandwidth reduction from the default value of 16 kHz to 8 kHz was evaluated prospectively in 50 patients referred for MR imaging of the head. On intermediate (2,000/30 [repetition time msec/echo time msec]) and more T2-weighted (2,000/90) studies, there were no definite missed diagnoses and no diagnostically important changes in lesion characteristics when the reduced-bandwidth technique was used to obtain half- or quarter-time studies, excluding differences attributable to unintentional changes in patient position between image acquisitions. Chemical shift misregistration artifacts associated with reduced bandwidth are easily recognized with experience and do not interfere with diagnosis, as the artifacts occur in characteristic locations and diminish in most anatomic locations with increasing echo time. This study suggests the feasibility of reduced-bandwidth techniques in clinical MR imaging of the head at high field strength to achieve an increased S/N, to decrease imaging time, or to obtain images in additional projections.