gebhart/patrepeval huggingface dataset:
pH and pKDeterminations by High-Resolution Solid-State13C NMR:  Acid−Base and Tautomeric Equilibria of Lyophilizedl-Histidine (2002)

Acid-base properties of lyophilized powders of L-histidine have been systematically investigated using parent solutions at pH varying from 1.8 to 10. For the first time, high-resolution solid-state 13C NMR was shown to allow separate observation of all three acid-base pairs in the successive deprotonations of the carboxylic end, the imidazolium cation, and the terminal ammonio group of histidine. 1H CRAMPS NMR spectra directly visualize the absence of the N3-H(pi) tautomer in neutral and anionic species. Solid-state titration shifts are enlarged by approximately 1-4 ppm with respect to those measured in solution, permitting unambiguous observation of conjugate acid-base pairs. Calculated pK's from solid-state acid-to-base ratios r are found equal to those classically measured in solution at 0 degrees C with a similar ionic strength of 0.1 mol x dm(-3). This proves that natural-abundance 13C solid-state determinations of r can be used to measure pK's in parent solutions without recourse to full titration curves and subsequent curve-fitting procedures. Such an approach also leads to noninvasive characterizations of the acidity of lyophilized powders, i.e., to the prediction of in situ pH of products obtained after rehydration and solubilization of powders. These results show the possibility of measuring the pK of nonvolatile acidic substrates dissolved in any sublimable solvent through lyophilization of the investigated solutions; this leads the way to pH and pK determinations when electrochemical or spectrophotometric measurements are impossible or ambiguous, e.g., for concentrated solutions, polyacids, or mixtures of acidic solutes, and possibly to the establishment of pK scales in nonaqueous solvents and in melts.
Lithium storage in nitrogen-rich mesoporous carbon materials (2012)

Nitrogen-rich mesoporous carbon materials were obtained by pyrolyzing gelatin between 700 and 900 °C with a nano-CaCO3 template. The mesoporous structure and the high nitrogen content endowed these materials with reversible capacities up to ca. 1200 mA h g−1. The high specific surface area and the nitrogen doping are responsible for the capacity loss in the initial cycle. FTIR and XPS studies indicate that the nitrogen in the material exists in the form of pyridinic, pyrrolic/pyridonic and graphitic nitrogen. The Raman spectroscopic analysis indicates that the structure of the mesoporous carbon becomes more disordered during discharge and is restored during recharge, a behavior similar to that in nitrogen-free hard carbon materials. The reversible structural variation of these carbon materials ensures their high cyclic reversibility.
Improving the beam quality of Mid-IR OPOs using an unstable resonator (2003)

We report a 400 % improvement in the beam quality of a Nd:YAG (0.5 Joule) pumped LiNbO_3 mid-IR OPO using an unstable resonator. The beam quality, M^2, was improved from 12.5 to 3.
iPTR: Learning a representation for interactive program translation retrieval (2021)

Program translation contributes to many real world scenarios, such as porting codebases written in an obsolete or deprecated language to a modern one or re-implementing existing projects in one's preferred programming language. Existing data-driven approaches either require large amounts of training data or neglect significant characteristics of programs. In this paper, we present iPTR for interactive code translation retrieval from Big Code. iPTR uses a novel code representation technique that encodes structural characteristics of a program and a predictive transformation technique to transform the representation into the target programming language. The transformed representation is used for code retrieval from Big Code. With our succinct representation, the user can easily update and correct the returned results to improve the retrieval process. Our experiments show that iPTR outperforms supervised baselines in terms of program accuracy.
A robust approach to face and eyes detection from images with cluttered background (2002)

Automatic face location in complex scenes is extremely challenging in human face recognition systems. Further more, the facial features detection also plays an important role. The paper presents a scheme for robust face and eyes detection from an image. The scheme uses the Gaussian steerable filter to search and detect the facial feature (preattentive feature) roughly in an image. The face model is investigated to locate the whole face and facial features, such as eyes, nose and mouth. Here, multiple evidences are used in the face location and eyes detection. One important feature is the structural information of the face, i.e. facial components of certain structure. The other is the symmetry property of the face, here only the front face with certain pose variation is considered. It will reduce the computation greatly. For facial components detection, some image features and PCA features are used for verification from the candidates detected before. Experiments show that the algorithm is robust and fast.
Dry Immersion as a Ground-Based Model of Microgravity Physiological Effects (2019)

Dry immersion (DI) is one of the most widely used ground models of microgravity. DI accurately and rapidly reproduces most of physiological effects of short-term space flights. The model simulates such factors of space flight as lack of support, mechanical and axial unloading as well as physical inactivity. The current manuscript gathers the results of physiological studies performed from the time of the model's development. This review describes the changes induced by DI of different duration (from few hours to 56 days) in the neuromuscular, sensory-motor, cardiorespiratory, digestive and excretory, and immune systems, as well as in the metabolism and hemodynamics. DI reproduces practically the full spectrum of changes in the body systems during the exposure to microgravity. The numerous publications from Russian researchers, which until present were mostly inaccessible for scientists from other countries are summarized in this work. These data demonstrated and validated DI as a ground-based model for simulation of physiological effects of weightlessness. The magnitude and rate of physiological changes during DI makes this method advantageous as compared with other ground-based microgravity models. The actual and potential uses of the model are discussed in the context of fundamental studies and applications for Earth medicine.
Ibuprofen degradation using a Co-doped carbon matrix derived from peat as a peroxymonosulphate activator (2020)

The wider presence of pharmaceuticals and personal care products in nature is a major cause for concern in society. Among pharmaceuticals, the anti-inflammatory drug ibuprofen has commonly been found in aquatic and soil environments. We produced a Co-doped carbon matrix (Co-P 850) through the carbonization of Co<sup>2+</sup> saturated peat and used it as a peroxymonosulphate activator to aid ibuprofen degradation. The properties of Co-P 850 were analysed using field emission scanning electron microscopy, energy filtered transmission electron microscopy and X-ray photoelectron spectroscopy. The characterization results showed that Co/Fe oxides were generated and tightly embedded into the carbon matrix after carbonization. The degradation results indicated that high temperature and slightly acidic to neutral conditions (pH = 5 to 7.5) promoted ibuprofen degradation efficiency in the Co-P 850/peroxymonosulphate system. Analysis showed that approx. 52% and 75% of the dissolved organic carbon was removed after 2 h and 5 h of reaction time, respectively. Furthermore, the existence of chloride and bicarbonate had adverse effects on the degradation of ibuprofen. Quenching experiments and electron paramagnetic resonance analysis confirmed that SO<sub>4</sub><sup>·-</sup>, ·OH and O<sub>2</sub><sup>·-</sup> radicals together contributed to the high ibuprofen degradation efficiency. In addition, we identified 13 degradation intermediate compounds and an ibuprofen degradation pathway by mass spectrometry analysis and quantum computing. Based on the results and methods presented in this study, we propose a novel way for the synthesis of a Co-doped catalyst from spent NaOH-treated peat and the efficient catalytic degradation of ibuprofen from contaminated water.
ChemInform Abstract: Titanium(III) Sulfate as New Negative Electrode for Sodium‐Ion Batteries. (2013)

Abstract Ti 2 (SO 4 ) 3 is prepared by treatment of Ti metal powder with conc.
Possible depth-resolved reconstruction of shear moduli in the cornea following collagen crosslinking (CXL) with optical coherence tomography and elastography (2023)

Corneal collagen crosslinking (CXL) is commonly used to prevent or treat keratoconus. Although changes in corneal stiffness induced by CXL surgery can be monitored with non-contact dynamic optical coherence elastography (OCE) by tracking mechanical wave propagation, depth dependent changes are still unclear if the cornea is not crosslinked through the whole depth. Here, phase-decorrelation measurements on optical coherence tomography (OCT) structural images are combined with acoustic micro-tapping (A$μ$T) OCE to explore possible reconstruction of depth-dependent stiffness within crosslinked corneas in an ex vivo human cornea sample. Experimental OCT images are analyzed to define the penetration depth of CXL into the cornea. In a representative ex vivo human cornea sample, crosslinking depth varied from $\sim 100μm$ in the periphery to $\sim 150μm$ in the cornea center and exhibited a sharp in-depth transition between crosslinked and untreated areas. This information was used in an analytical two-layer guided wave propagation model to quantify the stiffness of the treated layer. We also discuss how the elastic moduli of partially CXL-treated cornea layers reflect the effective engineering stiffness of the entire cornea to properly quantify corneal deformation.
Synthetic Study on Carthamin, Part 4. Improved Synthesis of a C-Glycosyl Quinochalcone by Installation of a Side Chain through Regioselective De-O-methylation and Acyl Rearrangement (2021)

Abstract We report an improved synthesis of a C-Glycosyl quinochalcone that is a key intermediate in our total synthesis of carthamin, a natural red pigment of traditional heritage. The C-glycosyl quinochalcone is prepared by regioselective de-O-methylation of a C-glycosyl bromodienone, and installation of a p-coumaroyl side chain through an O→C acyl rearrangement.
Fractal Characteristics of Combustion Noise (2017)

Fractal analysis is undertaken to characterize flame surface fluctuations on an unconfined turbulent premixed flame and the resulting far-field acoustics fluctuations. Results indicate that combustion noise is monofractal and is characterized by an anti-correlated structure with a Hurst exponent less than 0.5. The anti-correlated nature was identified in the pressure fluctuations as well as flame surface fluctuations for small time scales. Additionally, results suggest that flame surface fluctuations are multifractal for large time scales. The calculated Hurst exponent increases noticeably with the equivalence ratio and decreases slightly with Reynolds number for the investigated operating conditions. Variation in the Hurst exponent for combustion noise data is compared with a case study of synthetic fluctuations comprised of linear combinations of white and 1/f2 noise. These results provide a more detailed characterization of the temporal structure of flame surface fluctuations and resulting noise emission from turbulent premixed flames than is presently known.
Novel Energy Harvesting Technologies for ICT Applications (2008)

In this paper an overview of novel scavenging approaches for almost autonomous ICT applications will be discussed and evaluated in terms of efficiency, integrability, cost and applicability in rugged environments. Various frequencies of potential scavenged power will be tested and different electronic scavenging configurations will be presented and benchmarked in comparison to commonly used approaches, such as solar cells or electromechanical couples. Their performance will be evaluated in metal-rich multipath indoor environments, as well as in multi-users outdoor and indoor rural and urban topologies.
Meeting the Need for GIS Skills in Developing Countries: The Case of Informal Settlements (2002)

Informal settlements are a chronic issue in developing countries. Management and formalisation processes require good spatial data and analytical tools. While software such as geographic information systems (GIS) are widely available, access to good data and skilled users may be limited. In this paper we suggest that digital multimedia learning tools, accessible via the World Wide Web (WWW) may be part of the solution. We present the rationale for, and structure of, a suite of prototype learning modules for neighbourhood operations. We illustrate the use of these operations by converting shack locations into population density maps for the Imizamo Yethu settlement near Cape Town, South Africa. This prototype forms a part of a larger web site that also includes background information, data sources and software.
Optimization Procedure for Improvement of Thermal Interruption Capability of Tandem-puffer Interrupting Chamber -90% SLF Interruption for the Rating of 63kA-50Hz- (2010)

63kA-50Hz 90% short line fault (L90) is severer than 50kA-60Hz L90 from the points of view of electric endurance and interruption window. Interruption criteria and an optimization method of the chamber design are discussed to improve thermal interruption capability with it. The combination of the SA (Simulated Annealing) and MMFD (Modified Method of Feasible Directions) is applied to the optimization procedure. The optimized chambers with superior electric reliability are designed at 63kA-50Hz to improve gas density at current zero in thermal volume. 63kA-50Hz L90 interruptions are performed with the new chamber. In addition, influence of gas blast angle of nozzle on L90 interruption is clarified.
Role of the P–F Bond in Fluoride-Promoted Aqueous VX Hydrolysis: An Experimental and Theoretical Study (2012)

Following our ongoing studies on the reactivity of the fluoride ion toward organophosphorus compounds, we established that the extremely toxic and environmentally persistent chemical warfare agent VX (O-ethyl S-2-(diisopropylamino)ethyl methylphosphonothioate) is exclusively and rapidly degraded to the nontoxic product EMPA (ethyl methylphosphonic acid) even in dilute aqueous solutions of fluoride. The unique role of the P-F bond formation in the reaction mechanism was explored using both experimental and computational mechanistic studies. In most cases, the "G-analogue" (O-ethyl methylphosphonofluoridate, Et-G) was observed as an intermediate. Noteworthy and of practical importance is the fact that the toxic side product desethyl-VX, which is formed in substantial quantities during the slow degradation of VX in unbuffered water, is completely avoided in the presence of fluoride. A computational study on a VX-model, O,S-diethyl methylphosphonothioate (1), clarifies the distinctive tendency of aqueous fluoride ions to react with such organophosphorus compounds. The facility of the degradation process even in dilute fluoride solutions is due to the increased reactivity of fluoride, which is caused by the significant low activation barrier for the P-F bond formation. In addition, the unique nucleophilicity of fluoride versus hydroxide toward VX, in contrast to their relative basicity, is discussed. Although the reaction outcomes were similar, much slower reaction rates were observed experimentally for the VX-model (1) in comparison to VX.
A 140‐Kilodalton Protein Is Released from Cultured Astrocytes by Phosphatidylinositol Phospholipase C (1988)

Astrocytes in culture synthesize a 140-kilodalton (140-kD) protein (protein 140) that is released into the medium on incubation with phosphatidylinositol phospholipase C. This molecule therefore belongs to the class of proteins anchored to the external side of the cell membrane through a glycolipid moiety. Protein 140 is present in astrocyte cultures derived from two different regions of the brain and is not expressed by neurons in vitro. It differs from neuronal cell adhesion molecule 120 or 140 and is probably identical to a protein of 140 kD present in C6 glioma cells.
Reactive scattering from double minimum potentials: Li+ catalyzed elimination reactions of alkyl halides (1987)

We present a study of the dehydrohalogenation reactions of Li+ with isopropyl chloride (IPC), n-propyl chloride (NPC), and isopropyl bromide (IPB) over the collision energy range from 0.6 to 1.7 eV. Full differential cross sections at collision energies up to 1.2 eV show increasing asymmetry in the angular distributions as a function of initial collision energy and suggest that the reactions take place on a time scale of 0.2 ps. The observation of Li+ nonreactively ejected from the initial encounter complex formed by approaching reactants is consistent with a double minimum reaction coordinate and a comparison of the nonreactive flux with the flux for elimination products allows an estimate of the heights of intermediate isomerization barriers separating the wells on the potential surface. The barrier heights are in the order IPC&amp;lt;IPB&amp;lt;NPC, consistent with a transition state at the isomerization barrier in which a significant charge has developed on the carbon attached to the halogen. The kinetic energy distributions for Li+(HX) and Li+(C3H6) products and nonreactively scattered Li+ are in reasonable agreement with phase space theory calculations which include all product vibrational modes. The energy dependence of the Li+(HX)/Li+(C3H6) branching ratio can be accounted for quantitatively by statistical calculations which include the increasing importance of dissociation of the products with increasing collision energy. The discrepancy between the statistical recoil energy distributions and apparent complex lifetimes several orders of magnitude shorter than the predictions of RRKM theory can be understood in terms of incomplete transfer of energy from the incident Li+ to the internal degrees of freedom of the initial encounter complex, resulting in a density of complex states much lower than statistical.
Removal of Cr(VI) from aqueous solution by coal flyash adsorption I: Characteristics of chromium adsorption on flyash (1999)

The removal of Cr(VI) by adsorption on coal flyash is investigated. Batch adsorption studies demonstrate that flyash has a significant capacity for adsorption of Cr(VI) from aqueous solution. The specific surface areas of the coal flyash are calculated to be 17.3 m2/g. The removal of Cr(VI) can be described by Langmuir isotherm model with the maximum sorption capacities of 18.28 mg/g. The desorption studies are also performed and the results show that the amount of Cr(VI) eluted by distilled water and by 0.01 M NaOH in 10h is insignificant. Approximately 16% and 50% Cr(VI) adsorbed on flyash can be eluted by 0.1 M and 1 M NaOH.
Air Interface and Physical Layer techniques for 60 GHz WPANs (2006)

Thanks to the unprecedented availability of huge bandwidth, the capacity offered by wireless systems in the 60 GHz band can exceed the mythical barrier of 1 Gbps wireless, enabling the deployment of new applications. However, the performance can be limited by the non-ideality of the analog front-ends, multipath fading and the difficulty to achieve a reasonable link budget at high data rates. The goal of this paper is to introduce high rate communications in the 60 GHz band and the associated challenges. We will first introduce WPANs in the 60 GHz band, describing the possible applications, the propagation channel and the standardization context. Furthermore, based on the characteristics of the propagation channel, we will show that beamforming is desirable to boost the link budget, reduce interference and, in some cases, reduce multipath. Next, we will introduce candidate PHY layer solutions that at the same time meet the throughput requirements and relax the analog front-end design. Our solutions rely on the combination of block transmission combined with (nearly) constant envelope modulation: this provides low peak-to-average power ratios, easy equalization, good spectral properties and modest front-end requirements in terms of phase noise and ADC resolution. The receiver signal processing associated with the modulation techniques will be described and link level simulation results will be provided, highlighting the "front-end friendliness" of the modulation technique
Forced Response of a Swirling, Premixed Flame to Flow Disturbances (2006)

This paper presents measurements of the nonlinear response of a premixed flame to harmonic oscillations. These measurements were obtained to improve understanding of nonlinear flame dynamics in unstable combustors. Simultaneous measurements of CH ∗ and OH ∗ chemiluminescence, pressure, and velocity were obtained over a range of forcing amplitudes and frequencies. These data show that the flame chemiluminescence response to imposed oscillations saturates at pressure and velocity amplitudes on the order of p � /p0 ∼ 0.02 and u � /u0 ∼ 0.3. The value of the fluctuating to the mean chemiluminescence signal at saturation varied with equivalence ratio. The phase between the chemiluminescence and acoustic signal also exhibits substantial amplitude dependence, even at driving levels where their amplitude ratios are nearly linear. In contrast, the pressure-velocity relationship remains linear with constant phase over the entire amplitude range. Thus, these results suggest that the nonlinear dynamics of premixed combustors are controlled by the acoustics-heat-release relationship, as opposed to gas dynamical processes. The mechanism for saturation of the flame response appears to be caused by nonlinear interactions between the flow forcing and the parametric flame instability, possibly through their impact on the fluctuating flame position. This parametric instability occurs at half the forcing frequency and is caused by the oscillating flow acceleration in the presence of the density jump at the flame. To our knowledge, this observation of the parametric instability is the first in a turbulent, swirl-stabilized flame. Interactions between the nonlinear heat release and linear combustor acoustics were characterized by sweeping the driving frequency through a resonant combustor frequency. With increasing driving amplitude, the resulting frequency response curves began to saturate in amplitude and bend over toward lower frequencies. Similar to the classical nonlinear Duffing oscillator, this bending of the frequency response curves manifests itself as a subcritical bifurcation in combustor response, whose gain and phase exhibited jumps and hysteresis. The bifurcation structure was measured in detail over a range of conditions and shown to have a two-dimensional dependence upon both amplitude and frequency.
Neonatal cavernous carotid artery aneurysm (2005)

Neonatal intracranial aneurysms are rare. The authors report the case of a 4-week-old girl who presented with left-eye ptosis and proptosis. Computerized tomography scanning and magnetic resonance imaging demonstrated a mass involving the left cavernous sinus and middle cranial fossa. Cerebral angiography revealed a large complex left cavernous carotid artery (CA) aneurysm. The patient underwent endovascular treatment in which detachable coils and N-butyl cyanoacrylate glue were used to achieve complete obliteration of the aneurysm. To the authors' knowledge, this is the first reported neonatal intracranial aneurysm originating from the cavernous CA and treated endovascularly. The authors review the literature on neonatal intracranial aneurysms.