gebhart/patrepeval huggingface dataset:
Cathode Catalyst Layer Design with Graded Porous Structure for Proton Exchange Membrane Fuel Cells (2019)

Cathode catalyst layer (CL) design is important for improved performance, durability and stability of proton exchange membrane fuel cells (PEMFCs). An effective cathode CL must serve multiple functions simultaneously: electron and H + conduction, O 2 or H 2 supply, and effective water management. The reaction in the CL requires three-phase boundaries (or interfaces) among ionomer (for proton transfer), platinum (for catalysis), and carbon (for electron transfer), as well as voids (reactant diffusion); an optimized cathode CL structure should have micropores and mesopores to balance water egress and O 2 diffusion. Our previous research showed that increasing microporosity in the cathode CL increases the power production of the PEMFCs [1]. Modeling indicates that high CL microporosity enhances water evaporation, which reduces mass transport resistances to enable higher power production [2]. Meanwhile, low microporosity encourages liquid water retention. It is known that catalyst support type has a profound effect on electrode porosity, influencing both micro- and mesoporosity [3, 4]. By constructing electrodes with layers of different carbon supported catalyst types, we demonstrate that we can create porosity gradients in the CLs that vary the electrode water management properties and the power of the PEMFC. Two different types of commercial platinum/carbon electrocatalysts are used in dual cathode CLs – 40 wt. % Pt on Vulcan carbon (Pt/VC) having low micropores and low porosity and 40 wt. % Pt on Ketjen black (Pt/KB) having large micropores and high porosity. CLs are created with both homogeneous porosity in the Z direction (Figure 1a), and compared to ones with non-uniform porosity across the Z-direction (Figure 1b). The microstructure of these cathode CLs is characterized using N 2 -sorption porosimetry. The CLs are assembled into PEMFCs and probed with polarization curves (at 100, 50 and 25% RH), cyclic voltammetry, O 2 gain, electrochemical impedance spectroscopy, and limiting current measurements to quantify the sources of mass transport resistance. The results indicate that the regions with low microporosity encourage liquid water retention, while high microporosity encourages water evaporation. These countering actions are balanced for high CL hydration and gas diffusion, and better PEMFC performance. References [1] Y. Garsany, R.W. Atkinson, M.B. Sassin, R.M.E. Hjelm, B.D. Gould, K.E. Swider-Lyons, J. Electrochem. Soc., 165 (2018) F381-F391. [2] M. Eikerling, J. Electrochem. Soc., 153 (2006) E58-E70. [3] T. Soboleva, K. Malek, Z. Xie, T. Navessin, S. Holdcroft, ACS Appl. Mater. Interfaces, 3 (2011) 1827-1837. [4] Y.-C. Park, H. Tokiwa, K. Kakinuma, M. Watanabe, M. Uchida, Journal of Power Sources, 315 (2016) 179-191. Figure 1
Resistivities of Thin Film Transition Metal Silicides (1982)

Resistivities of the transition metal silicides have been determined. The silicides were formed either by reacting thin metal films with silicon or polysilicon substrates or by sintering cosputtered (metal + silicon) films on silicon, polysilicon, or oxide substrates. The sheet resistance of the film was determined as a function of the sintering temperature, in the range of 300°–1100°C. At the same time, the intermetallic compound formation due to sintering at different temperatures was investigated by the use of x‐ray diffraction technique. It was found that the initial interaction between the metallic film and the substrate was slower for polysilicon substrates compared to silicon substrates; the end product, however, was identical. The resistivity of the refactory metal silicides was lowest for the disilicide and increased with increasing atomic number in a given period of the periodic table. The spread in the resistivities of the 4th period silicides was found to be larger than that of the 6th period silicides. Similarities with the borides, carbides, and nitrides of the same metals are pointed out. On the other hand, for VIII group metal silicides, resistivities were low and no correlation was observed.
Common-Mode Noise Reduction In Interferometric Fiberoptic Sensors Using Electrooptic Feedback (1990)

Common-mode perturbations are an important subset of the environmental variations which affect the accuracy and stability of interferometric fiberoptic sensors. These effects, among which are source wavelength drift and spatially uniform temperature and pressure variations, alter the phase shifts in each of the optical paths in the fiber circuit in proportion to the optical path length. Earlier work showed that a recirculating delay line fiberoptic sensor could be modified to compensate for common-mode perturbations, but at the cost of some loss in measurand sensitivity. In this paper, we employ transmittance-dependent electrooptic feedback in an enhanced Mach-Zehnder fiberoptic interferometer to compensate for common-mode perturbations, while enhancing by aproximately an order of magnitude the measurand sensitivity found in the conventional Mach-Zehnder fiber interferometer.
Meniscus-Assisted High-Efficiency Magnetic Collection and Separation for EWOD Droplet Microfluidics (2009)

This paper describes a technique to increase the efficiency of magnetic concentration on an electrowetting-on-dielectric (EWOD)-based droplet (digital) microfluidic platform operated in air, i.e., on dry surface. Key differences in the force scenario for droplet microfluidics vis-a-vis the conventional continuous microfluidic systems are identified to explain the rationale behind the proposed idea. In particular, the weakness of the magnetic force relative to the bead-substrate adhesion and the liquid-air interfacial tension is highlighted, and a new technique to achieve high-efficiency magnetic collection with the assistance of the interfacial force is proposed. An improvement in collection efficiency (e.g., from ~ 73% to ~ 99%) is observed with the new technique of ldquomeniscus-assisted magnetic bead collectionrdquo. In addition, isolation of the magnetic species from a mixed sample of magnetic and nonmagnetic beads is demonstrated. Comparison with other related reports is also presented.
Kinetics of Living Radical Polymerization (2000)

Activation processes and polymerization rates of several variants of living radical polymerization (LRP) are discussed. Despite the presence of side reactions such as termination and initiation, the products from LRP can have a low polydispersity, provided that the number of terminated chains is small compared to the number of potentially active chains. A large rate constant of activation, kact, is another fundamental requisite for low polydispersities. Experimental studies on kact have clarified the exact mechanisms of activation in several LRP systems. The magnitudes of kact have been found to largely differ from system to system. Because of bimolecular termination, which is inevitable in LRP as well as in conventional radical polymerization, the time-conversion curves of LRP have several characteristic features depending on experimental conditions, such as the presence or absence of conventional initiation and/or an extra amount of stable free radicals or the like. A new analytical rate equation applicable to such general cases is presented.
Automatic Crossover Frequency Selection for Multichannel Home-Theater Applications (2005)

Given a multichannel loudspeaker system, the selection of the crossover frequency between the sub-woofer and the satellite speakers is important for accurate (i.e., distortion-free), reproduction of playback sound. Presently, many home-theater systems have selectable crossover frequencies which are either set by the consumer through listening tests. Alternatively, if the loudspeakers are industry certified, the crossover frequency is set at 80 Hz. A desirable feature is that, besides distortion-free sound output from the individual subwoofer and the satellite speakers, the combined sub-woofer and satellite room acoustical response should exhibit negligible variations around the selected crossover frequency. In this paper, we present an automatic crossover frequency selection algorithm based on an objective measure (viz., the spectral deviation measure) for multichannel home-theater applications that allows better control of the combined subwoofer-satellite response, thereby significantly improving audio quality.
Adaptive Model Generation for Intrusion Detection Systems (2000)

In this paper, we present adaptive model generation, a method for automatically building detection models for data-mining based intrusion detection systems. Using the same data collected by intrusion detection sensors, adaptive model generation builds detection models on the fly. This significantly reduces the deployment cost of an intrusion detection system because it does not require building a training set. We present a real time system architecture and efficient implementation of automatic model generation. The system uses a model building algorithm that builds anomaly detection models over noisy data. We evaluate the system using the DARPA Intrusion Detection Evaluation data and show an increase in detection performance as more data is collected by the sensors.
Characterization of the Human and Mouse Sphingosine 1-Phosphate Receptor, S1P<sub>5</sub> (Edg-8):  Structure−Activity Relationship of Sphingosine1-Phosphate Receptors (2001)

Five G protein-coupled receptors (S1P(1)/Edg-1, S1P(3)/Edg-3, S1P(2)/Edg-5, S1P(4)/Edg-6, and S1P(5)/Edg-8) for the intercellular lipid mediator sphingosine 1-phosphate have been cloned and characterized. We found human and mouse sequences closely related to rat S1P(5) (97% identical amino acids) and report now the characterization of the human and mouse S1P(5) gene products as encoding sphingosine 1-phosphate receptors. When HEK293T cells were cotransfected with S1P(5) and G protein DNAs, prepared membranes showed sphingosine 1-phosphate concentration-dependent increases in [gamma-(35)S]GTP binding (EC(50) = 12.7 nM). The lipid mediator inhibited forskolin-driven rises in cAMP by greater than 80% after introduction of the mouse or human S1P(5) DNAs into rat hepatoma RH7777 cells (IC(50) = 0.22 nM). This response is blocked fully by prior treatment of cultures with pertussis toxin, thus implicating signaling through G(i/o)alpha proteins. Northern blot analysis showed high expression of human S1P(5) mRNA in spleen, corpus collosum, peripheral blood leukocytes, placenta, lung, aorta, and fetal tissues. Mouse S1P(5) mRNA is also expressed in spleen and brain. Finally, we found that one enantiomer of a sphingosine 1-phosphate analogue wherein the 3-hydroxyl and 4,5-olefin are replaced by an amide functionality shows some selectivity as an agonist S1P(1) and S1P(3) vs S1P(2) and S1P(5).
Cardiac gating with a pulse oximeter for dual-energy imaging (2008)

The development and evaluation of a prototype cardiac gating system for double-shot dual-energy (DE) imaging is described. By acquiring both low- and high-kVp images during the resting phase of the cardiac cycle (diastole), heart misalignment between images can be reduced, thereby decreasing the magnitude of cardiac motion artifacts. For this initial implementation, a fingertip pulse oximeter was employed to measure the peripheral pulse waveform ('plethysmogram'), offering potential logistic, cost and workflow advantages compared to an electrocardiogram. A gating method was developed that accommodates temporal delays due to physiological pulse propagation, oximeter waveform processing and the imaging system (software, filter-wheel, anti-scatter Bucky-grid and flat-panel detector). Modeling the diastolic period allowed the calculation of an implemented delay, t(imp), required to trigger correctly during diastole at any patient heart rate (HR). The model suggests a triggering scheme characterized by two HR regimes, separated by a threshold, HR(thresh). For rates at or below HR(thresh), sufficient time exists to expose on the same heartbeat as the plethysmogram pulse [t(imp)(HR) = 0]. Above HR(thresh), a characteristic t(imp)(HR) delays exposure to the subsequent heartbeat, accounting for all fixed and variable system delays. Performance was evaluated in terms of accuracy and precision of diastole-trigger coincidence and quantitative evaluation of artifact severity in gated and ungated DE images. Initial implementation indicated 85% accuracy in diastole-trigger coincidence. Through the identification of an improved HR estimation method (modified temporal smoothing of the oximeter waveform), trigger accuracy of 100% could be achieved with improved precision. To quantify the effect of the gating system on DE image quality, human observer tests were conducted to measure the magnitude of cardiac artifact under conditions of successful and unsuccessful diastolic gating. Six observers independently measured the artifact in 111 patient DE images. The data indicate that successful diastolic gating results in a statistically significant reduction (p < 0.001) in the magnitude of cardiac motion artifact, with residual artifact attributed primarily to gross patient motion.
A New Beamformer Design Algorithm for Microphone Arrays (2006)

This paper presents a generic beamformer design algorithm for arbitrary microphone array geometry. It makes efficient use of noise models for ambient and instrumental and microphone directivity patterns. By using a new definition of the target criterion and replacing a multi-dimensional optimization with a much simpler one-dimensional search, we can compute near-optimal solutions in reasonable time. The designed beams achieve noise suppression levels between 10 and 15 dB, for microphone arrays with four to eight elements, and linear and circular geometries. The fast beamformer real-time processing engine consumes less than 2% of the CPU power of a modern personal computer, for a four-microphone array.
Temperature compensation of fiber-optic current sensors (2014)

We report the first fabrication of polarization rocking filters in a highly birefringent elliptical microfiber. The rocking filters are made by periodically heating/twisting a microfiber with an ellipticity of ~0.7 and a diameter of ~2.8 μm along its major axis. Strong input polarization suppression of ~20 dB is achieved at a resonant wavelength of ~1556.4 nm with a device length of ~3.12 mm. High-order polarization rocking filter was used to measure the refractive index with sensitivity of 32036 nm/RIU.
Cone-beam image reconstruction using spherical harmonics (2001)

Image reconstruction from cone-beam projections is required for both x-ray computed tomography (CT) and single photon emission computed tomography (SPECT). Grangeat's algorithm accurately performs cone-beam reconstruction provided that Tuy's data sufficiency condition is satisfied and projections are complete. The algorithm consists of three stages: (a) Forming weighted plane integrals by calculating the line integrals on the cone-beam detector, and obtaining the first derivative of the plane integrals (3D Radon transform) by taking the derivative of the weighted plane integrals. (b) Rebinning the data and calculating the second derivative with respect to the normal to the plane. (c) Reconstructing the image using the 3D Radon backprojection. A new method for implementing the first stage of Grangeat's algorithm was developed using spherical harmonics. The method assumes that the detector is large enough to image the whole object without truncation. Computer simulations show that if the trajectory of the cone vertex satisfies Tuy's data sufficiency condition, the proposed algorithm provides an exact reconstruction.
Dynamic Phasor Model-Based Synchrophasor Estimation Algorithm for M-Class PMU (2015)

Phasor measurement units (PMUs) are taking an increasingly important role in power system dynamic security monitoring and control. However, traditional discrete Fourier transforms (DFTs) used by PMUs cannot obtain accurate phasor measurements during frequency excursion and transient events, being limited by its static phasor model. In this paper, a synchrophasor estimation algorithm for M-class PMUs based on the dynamic phasor model is proposed. In this algorithm, the dynamic phasor within an observation data window is approximated by the second-order Taylor expansion. The linear relationship between the second-order coefficients of the Taylor expansion and the errors caused by the DFT averaging effect is explored. Then, the linear relationship is used to compensate the raw measurement errors under a dynamic condition. Two digital filters are applied not only to eliminate the spectrum leakage caused by the dynamic inputs, but also to make the PMU immune to the out-of-band signals. The algorithm is investigated through simulation, laboratory experiments, and real data from the power system according to IEEE C37.118.1. The test results demonstrate that the proposed algorithm can meet the requirements of the standards.
The three‐dimensional structure of human transaldolase (2000)

The crystal structure of human transaldolase has been determined to 2.45 A resolution. The enzyme folds into an alpha/beta barrel structure and is thus similar in structure to other class I aldolases. Structure-based sequence alignment of available sequences of the transaldolase subfamily reveals that eight active site residues are invariant in the whole subfamily. Other invariant residues are mainly involved in the formation of the hydrophobic core of the enzyme. Noteworthy is a hydrophobic cluster consisting of five invariant residues. Human transaldolase has been implicated as an autoantigen in multiple sclerosis and four immunodominant peptide segments are located at the surface of the enzyme, accessible to autoantibodies.
AAPG Methods in Exploration No. 13, Chapter 5: Developments in NMR Logging (2002)

In formation evaluation, nuclear magnetic resonance (NMR) logging has become a reliable and accurate alternative to neutron, density, and sonic measurements for determining porosity. Because of its capability of measuring fluid properties, NMR generally allows log analysts to categorize the measured porosity and to classify the pore fluid in most reservoirs.
Controlling the Selectivity of Competitive Nitroaldol Condensation by Using a Bifunctionalized Mesoporous Silica Nanosphere-Based Catalytic System (2004)

A series of bifunctionalized mesoporous silica nanosphere-based (MSN) heterogeneous catalysts for the nitroaldol (Henry) reaction have been synthesized. A common 3-[2-(2-aminoethylamino)ethylamino]propyl (AEP) primary group and three different secondary groups, ureidopropyl (UDP), mercaptopropyl (MP), and allyl (AL) functionalities, were incorporated to these mesoporous silica materials by introducing equal amounts of AEP-trimethoxysilane with UDP-, MP-, or AL-trialkoxysilane precursors to our previously reported co-condensation reaction. Structures and relative concentrations of the functional groups were detailed by solid-state NMR and other spectroscopic techniques. The AEP group served as a catalyst, and the other secondary groups provided different noncovalent interactions to reactants and thereby controlled the reaction selectivity. By varying the secondary group in these bifunctionalized MSN catalysts, we investigated the selectivity of a nitroaldol reaction of two competing benzaldehydes reacting with nitromethane by measuring the molar ratio of the nitroalkene products. The selectivity of the bifunctionalized MSN catalysts could be systematically tuned simply by varying the physicochemical properties of the pore surface-bound secondary groups, i.e., polarity and hydrophobicity.
Topographic Templating: Rectangular Symmetry Morphologies in a Topographically Templated Block Copolymer (Adv. Mater. 31/2012) (2012)

By functionalizing lithographically defined posts with a brush consisting of the majority block of a block copolymer, various morphologies can be formed in a templated self-assembled pattern, as reported by K. K. Berggren, C. A. Ross, and co-workers on page 4249. In the cover image, square-symmetric post arrays produce a similarly square-symmetric microdomain lattice, coincidentally doubling the pattern density.
Highly Efficient 1,4-Additions of Electron-Deficient Aryl Boronic Acids with a Novel Rhodium(I) Quinonoid Catalyst (2006)

Rhodium(I) quinonoid catalysts are a remarkably efficient new class of reagents for the conjugate addition of aryl boronic acids. Herein, we describe the use of these reagents in catalyzing the highly efficient addition of a broad range of boronic acids, including heteroaromatic and the first example of trihalogenated aryl boronic acids.
Two-modulator generalized ellipsometry: experiment and calibration (1997)

A two-modulator generalized ellipsometer is described that is capable of measuring all 16 elements of a sample Mueller matrix with four measurements made at different azimuthal orientations of the polarization state generator and polarization state detector. If the sample can be described with a Mueller-Jones matrix, only a single measurement is needed. Only two calibration steps are needed to determine the fundamental operating parameters of the instrument. A reflection measurement from silicon is presented as an example, which illustrates that the elements of the Mueller-Jones matrix can be measured to an accuracy of ~0.1-0.2%.
Corrosion resistance of a new, wrought Ni-Cr-Mo alloy (1997)

A new, nickel-based alloy resistant to a very wide range of corrosive media is described. The main alloying additions are chromium and molybdenum; however, the alloy also contains {approximately} 1.6% copper, which significantly enhances its resistance to dilute sulfuric and hydrochloric acids. The safe operating regimes for the alloy in these two acids are defined, as are its current and potential applications in the chemical process industries.
Structural diversity of selective COX-2 inhibitors (2004)

Non-steroidal anti-inflammatory drugs (NSAIDs) are among the most widely used agents in the treatment of pain and inflammation, especially rheumatoid arthritis [1]. The first NSAID aspirin was introduced over a century ago, and continues to be a popular over-the-counter medication in the treatment of the symptoms of pain and inflammation. The global production of aspirin is approximately 50,000 tons annually [2]. The pharmacological effects of NSAIDs arise from their inhibition of the prostaglandin synthase or cyclooxygenase (COX) isozymes [3]. COX isozymes catalyze the rate-limiting step in the arachidonic acid cascade involving the conversion of arachidonic acid to prostaglandin H2 (PGH2), the common biosynthetic precursor to prostaglandins and thromboxane (Fig. 1). These bioactive lipids mediate numerous physiological and pathophysiological effects, including pain, fever, inflammation, hemostasis, and regulation of renal function and maintenance of mucosal integrity in the stomach.