gebhart/patrepeval huggingface dataset:
Catalytic Functionalization of Carbon−Hydrogen and Carbon−Carbon Bonds in Protic Media (1998)

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCatalytic Functionalization of Carbon−Hydrogen and Carbon−Carbon Bonds in Protic MediaAyusman SenView Author Information Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 Cite this: Acc. Chem. Res. 1998, 31, 9, 550–557Publication Date (Web):May 23, 1998Publication History Received24 October 1997Published online23 May 1998Published inissue 1 September 1998https://pubs.acs.org/doi/10.1021/ar970290xhttps://doi.org/10.1021/ar970290xresearch-articleACS PublicationsCopyright © 1998 American Chemical SocietyRequest reuse permissionsArticle Views1859Altmetric-Citations281LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Alcohols,Hydrocarbons,Inorganic carbon compounds,Oxidation,Oxides Get e-Alerts
Collective diffusion in colloidal crystals (1991)

Electrostatically stabilized colloidal crystals prepared from aqueous suspensions of dyed polystyrene spheres compress locally when illuminated by intense laser light of wavelengths absorbed by the dye. The compression, which derives from the temperature dependence of the interparticle repulsive interaction, results in a concentration gradient where particles diffuse into the illuminated regions. The concentration gradient relaxes when the pump light is removed. We experimentally constrain particle diffusion to one dimension by creating a spatially periodic intensity grating which results in a periodic concentration profile. We measure the relaxation time constant of this concentration grating by monitoring the time-dependent transmitted intensity of a low intensity probe beam when the diffraction conditions are almost satisfied for the probe wavelength. The collective diffusion coefficient is found from the relaxation time constant.
Two parsing algorithms by means of finite state transducers (1994)

We present a new approach, illustrated by two algorithms, for parsing not only Finite State Grammars but also Context Free Grammars and their extension, by means of finite state machines. The basis is the computation of a fixed point of a finite-state function, i.e. a finite-state transducer. Using these techniques, we have built a program that parses French sentences with a grammar of more than 200,000 lexical rules with a typical response time of less than a second. The first algorithm computes a fixed point of a non-deterministic finite-state transducer and the second computes a fixed point of a deterministic bidirectional device called a bimachine. These two algorithms point out a new connection between the theory of parsing and the theory of representation of rational transductions.
The effect of gossypol on ATPase activity of the kidney. (1981)

The results of the present study have shown no change in the activity of ATPase of the renal cortex of rats administered gossypol for half a year. The Na+, K+-ATPase activity of the cellular membrane of renal cortex of guinea pigs fed with gossypol for 5 or 9 weeks is significantly altered. It seems possible to diminish or to delay the inhibition by allowing the guinea pigs a potassium-rich diet ad libitum. In vitro, gossypol inhibits significantly the activity of ATPase of the brain and the kidney of rats and guinea pigs uncompetitively. However, the inhibition of the ATPase of human fetus kidney is of a mixed type.
Differential Accumulation of Salicylic Acid and Salicylic Acid-Sensitive Catalase in Different Rice Tissues (1997)

We previously proposed that salicylic acid (SA)-sensitive catalases serve as biological targets of SA in plant defense responses. To further examine the role of SA-sensitive catalases, we have analyzed the relationship between SA levels and SA sensitivity of catalases in different rice (Oryza sativa) tissues. We show here that, whereas rice shoots contain extremely high levels of free SA, as previously reported (I. Raskin, H. Skubatz, W. Tang, B.J.D. Meeuse [1990] Ann Bot 66: 369-373; P. Silverman, M. Seskar, D. Kanter, P. Schweizer, J.-P. Metraux, I. Raskin [1995] Plant Physiol 108: 633-639), rice roots and cell-suspension cultures have very low SA levels. Catalases from different rice tissues also exhibit differences in sensitivity to SA. Catalase from rice shoots is insensitive to SA, but roots and cell-suspension cultures contain SA-sensitive catalase. The difference in SA sensitivity of catalases from these different tissues correlates with the tissue-specific expression of two catalase genes, CatA and CatB, which encode highly distinctive catalase proteins. CatA, which encodes a catalase with relatively low sequence homology to the tobacco SA-sensitive catalases, is expressed at high levels exclusively in the shoots. On the other hand, in roots and cell-suspension cultures, with northern analysis we detected expression of only the CatB gene, which encodes a catalase with higher sequence homology to tobacco catalases. The role of catalases in mediating some of the SA-induced responses is discussed in light of these results and the recently defined mechanisms of catalase inhibition by SA.
A Fast-Start Method for Computing the Inverse Tangent (2005)

In a search for an algorithm to compute atan(x) which has both low latency and few floating point instructions, an interesting variant of familiar trigonometry formulas was discovered that allow the start of argument reduction to commence before any references to tables stored in memory are needed. Low latency makes the method suitable for a closed subroutine, and few floating-point operations make the method advantageous for a software-pipelined implementation.
Unprecedented Mild Acid-Catalyzed Desilylation of the 2‘-O-<i>tert</i>-Butyldimethylsilyl Group from Chemically Synthesized Oligoribonucleotide Intermediates <i>via</i> Neighboring Group Participation of the Internucleotidic Phosphate Residue (1996)

Hydrolytic removal of the 2'-tert-butyldimethylsilyl (TBDMS) group from a 2'-O-TBDMS protected UpU dimer [U(2'-Si)pU] (1) (Si = TBDMS) and related derivatives under various acidic conditions was studied in detail. First, desilylation of 1 by use of acetic acid was examined. Consequently, we made the unprecedented discovery that cleavage of the 2'-silyl ether linkage occurred fastest at a very low concentration of acetic acid within the range of 5−10%, depending on the temperature. Formic acid could cleave the silyl ether much faster than acetic acid, but the relationship between the reaction rate and the concentration of acid was different from that of acetic acid. The use of 20−40% formic acid resulted in very effective elimination of the 2'-TBDMS group. Moreover, diluted HCl solution (pH 2.0) could cleave the Si−O bond faster than acetic acid at 30 °C. In contrast, the 2'-silyl group of the corresponding methylphosphonate derivative [U(2'-Si)p(Me)U] (3) was much more stable than that of 1. In the case of a diastereomeric mixture of the phosphorothioate dimer [U(2'-Si)psU] (2), a big difference in reaction rate between the Rp- and Sp-diastereomers was observed. These results strongly suggest that neighboring group participation of the 3'-5' phosphorodiester group is involved in the present acid-catalyzed 2'-desilylation. These conditions were successfully applied to the deprotection of the 2'-TBDMS group of an RNA intermediate which was chemically synthesized by the conventional phosphoramidite approach on a CPG gel.
Tripartite associations in snowbrush (<i>Ceanothus velutinus</i>): effect of vesicular–arbuscular mycorrhizae on growth, nodulation, and nitrogen fixation (1981)

Symbiotic associations were established between nitrogen-fixing nonleguminous (actinorrhizal) snowbrush (Ceanothus velutinus Dougl.) seedlings and two categories of microorganisms: vesicular–arbuscular (VA) mycorrhizal fungi and a filamentous actinomycete capable of inducing nodule formation. The actinomycete is housed in nodules where fixation of atmospheric dinitrogen occurs and is made available to the host plant; the mycorrhizal fungus is both inter- and intra-cellular within the root tissue and may be found within the nodules. The two major nutrients, N and P, are made available and can be supplied to the host plant by these two symbiotic microorganisms. The root system of snowbrush seedlings was dually colonized by VA mycorrhizal fungi and a nitrogen-fixing actinomycete and the possibility of a direct interaction between the endophytes in the symbioses was investigated. Dually infected plants showed increases in total dry weight of shoots and roots, number of nodules, weight of nodular tissue, as well as higher levels of N, Ca 2+ , and P, and an increase in nitrogenase activity as measured by acetylene reduction.
ε support vector machines (2009)

In this paper, the problem of adaptive channel equalization is considered. We extend the previous work in a new direction with periodic training sequence and formulate the original channel equalization problem into the equivalent linear regression in which − e support vector regression machines are proposed. Slack variables are introduced in our approach to solve the problem of quadratic programming derived from − e support vector regression machines. Simulation results show that the bit error rate of the proposed equalizer based on − e support vector regression machines comes near to that of the optimal equalizer and is better than that of wavelet neural network equalizer. Simulation results also support the rapid convergence of the proposed approach, which can meet the real- time requirement of time-varying channels effectively in modern digital communication systems.
Phosphodiesterases as Therapeutic Targets for Alzheimer's Disease (2012)

Alzheimer's disease (AD) is the most common form of dementia among the elderly. In AD patients, memory loss is accompanied by the formation of beta-amyloid plaques and the appearance of tau in a pathological form. Given the lack of effective treatments for AD, the development of new management strategies for these patients is critical. The continued failure to find effective therapies using molecules aimed at addressing the anti-beta amyloid pathology has led researchers to focus on other non-amyloid-based approaches to restore memory function. Promising non-amyloid related candidate targets include phosphosdiesterases (PDEs), and indeed, Rolipram, a specific PDE4 inhibitor, was the first compound found to effectively restore cognitive deficits in animal models of AD. More recently, PDE5 inhibitors have also been shown to effectively restore memory function. Accordingly, inhibitors of other members of the PDE family may also improve memory performance in AD and non-AD animal models. Hence, in this review, we will summarize the data supporting the use of PDE inhibitors as cognitive enhancers and we will discuss the possible mechanisms of action underlying these effects. We shall also adopt a medicinal chemistry perspective that leads us to propose the most promising PDE candidates on the basis of inhibitor selectivity, brain distribution, and mechanism of action.
Effects of attenuation on reflections: Experimental test (1984)

A well‐known effect of seismic wave attenuation is the change in frequency content and amplitude of a pulse propagating through a lossy medium. A related aspect of wave propagation in lossy media is the frequency dependence of the reflection coefficients. This phenomenon is studied here experimentally and by computer simulation. It is found that attenuation contrast has a relatively large effect on reflections when the acoustic impedance (i.e., density times velocity) difference of the two media is small. While this is a common situation in the upper crust of the earth, very low acoustic impedance contrast is difficult to create in the laboratory. By using carefully chosen samples of polymer and silicon rubber, we show that with low acoustic impedance contrast and high attenuation contrast, an increase in the amplitude of reflections due to Q contrast is observable. We also show that there is no observable phase effect due to the attenuation contrast. By measuring and simulating the reflected signals at angles of incidence to 30°, we find that the Q contrast effect is important only at small angles and that it dies out at large ones.
ALTERED BRAIN WAVE ACTIVITY IN PERSONS WITH CHRONIC SPINAL CORD INJURY (2007)

This study investigated brain wave activity associated with spinal cord injury (SCI). Electroencephalograms (EEG) were compared between 10 individuals with SCI and 10 age and sex matched able-bodied controls using a 64-channel EEG montage. SCI participants had chronic (>12 months) paraplegic clinically complete injuries. The 64 channels of EEG data were spread diffusely over the cortex and were compared for delta (2–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), and beta (13–30 Hz) wave components of the EEG frequency spectra. No significant magnitude or directional changes were found in the delta (2–4 Hz) or theta (4–8 Hz) wave frequency bands between these two groups. However, significant and consistent decreased alpha wave (8–13 Hz) and increased beta wave activity (13–30 Hz) were found in the SCI participants across the cortex compared to the able-bodied control group. These findings suggest that the SCI group have increased neural processing compared to the able-bodied individuals, which may be related to ongoing reorganization of brain structures following SCI.
Mandamus to Review Administrative Action in West Virginia (1957)

Limitation by law of governmental action and legal responsibility of officials are ramparts in defense of constitutional democracy. The American people expect all branches of government-executive and legislative, as well as judicial-to protect us against arbitrary official action. Lawyers, however, are primarily interested in judicial restraints and limitations upon officialdom. This article is an examination of the West Virginia law concerning one of the methods used by courts to control administrative officers-the writ of mandamus.
Influence of Water Content and Temperature on Molecular Mobility and Intracellular Glasses in Seeds and Pollen (1998)

Although the occurrence of intracellular glasses in seeds and pollen has been established, physical properties such as rotational correlation times and viscosity have not been studied extensively. Using electron paramagnetic resonance spectroscopy, we examined changes in the molecular mobility of the hydrophilic nitroxide spin probe 3-carboxy-proxyl during melting of intracellular glasses in axes of pea (Pisum sativum L.) seeds and cattail (Typha latifolia L. ) pollen. The rotational correlation time of the spin probe in intracellular glasses of both organisms was approximately 10(-3) s. Using the distance between the outer extrema of the electron paramagnetic resonance spectrum (2Azz) as a measure of molecular mobility, we found a sharp increase in mobility at a definite temperature during heating. This temperature increased with decreasing water content of the samples. Differential scanning calorimetry data on these samples indicated that this sharp increase corresponded to melting of the glassy matrix. Molecular mobility was found to be inversely correlated with storage stability. With decreasing water content, the molecular mobility reached a minimum, and increased again at very low water content. Minimum mobility and maximum storage stability occurred at a similar water content. This correlation suggests that storage stability might be at least partially controlled by molecular mobility. At low temperatures, when storage longevity cannot be determined on a realistic time scale, 2Azz measurements can provide an estimate of the optimum storage conditions.
Iminoribitol Transition State Analogue Inhibitors of Protozoan Nucleoside Hydrolases (1999)

Nucleoside N-ribohydrolases from protozoan parasites are targets for inhibitor design in these purine-auxotrophic organisms. Purine-specific and purine/pyrimidine-nonspecific nucleoside hydrolases have been reported. Iminoribitols that are 1-substituted with meta- and para-derivatized phenyl groups [(1S)-substituted 1, 4-dideoxy-1,4-imino-D-ribitols] are powerful inhibitors for the nonspecific nucleoside N-ribohydrolases, but are weak inhibitiors for purine-specific isozymes [Parkin, D. W., Limberg, G., Tyler, P. C., Furneaux, R. H., Chen, X.-Y., and Schramm, V. L. (1997) Biochemisty 36, 3528-3534]. Binding of these inhibitors to nonspecific nucleoside hydrolase occurs primarily via interaction with the iminoribitol, a ribooxocarbenium ion analogue of the transition state. Weaker interactions arise from hydrophobic interactions between the phenyl group and the purine/pyrimidine site. In contrast, the purine-specific enzymes obtain equal catalytic potential from leaving group activation and ribooxocarbenium ion formation. Knowledge of the reaction mechanisms and transition states for these enzymes has guided the design of isozyme-specific transition state analogue inhibitors. New synthetic efforts have produced novel inhibitors that incorporate features of the leaving group hydrogen-bonding sites while retaining the iminoribitol group. These compounds provide the first transition state analogue inhibitors for purine-specific nucleoside hydrolase. The most inhibitory 1-substituted iminoribitol heterocycle is a sub-nanomolar inhibitor for the purine-specific nucleoside hydrolase from Trypanosoma brucei brucei. Novel nanomolar inhibitors are also described for the nonspecific nucleoside hydrolase from Crithidia fasciculata. The compounds reported here are the most powerful iminoribitol inhibitors yet described for the nucleoside hydrolases.
Hydrogenation of a Chiral 1<i>H</i>-Benz[<i>de</i>]isoquinolin-1-one and an Equilibration Using Palladium Catalyst (1997)

The catalytic hydrogenation of a chiral 1H-benz[de]isoquinolin-1-one to palonosetron and the undesired diastereomer was optimized using a variety of conditions and catalysts. The most selective catalyst for the production of palonosetron was an unreduced palladium on carbon catalyst. The (+)- and (−)-camphorsulfonic acid salts of the 1H-benz[de]isoquinolin-1-one and the complex of the 1H-benz[de]isoquinolin-1-one with Mg2+ upon catalytic hydrogenation gave the greatest preference for the undesired diastereomer. An equilibration of the undesired diastereomer from hydrogenation and palonosetron as hydrochloride salts using hydrogen-activated palladium on carbon catalyst under a nitrogen atmosphere was developed. The procedure was used to recycle the hydrochloride salt of the undesired diastereomer from hydrogenation into pure palonosetron hydrochloride.
Investigation of cardiac fibroblasts using myocardial slices (2017)

Myocardial slices allow the study of CFs in a multicellular environment and may be used to effectively study mechanisms of cardiac fibrosis and potential targets.
Competition Between Chelating Agents and Roots as Factor Affecting Absorption of Iron and Other Ions by Plant Species (1960)

Absorption of iron by plants can be increased by adding a chelating azent to a soil (2, 7, 24). Jacobson (9) found that 5 or 10 ppm of iron supplied as FeEDTA in solution cultures provided adequate iron to the plant at high pH. Other workers (7, 11, 12, 19, 20, 23, 24, 25) have confirmed these observations. Plant responses to chelate applications have been shown to differ between plant species (2) and the effectiveness of chelating agents on specific soils are known to differ (2, 24). There has been some in- dication (4) that roots and chelating agent compete for the Fe in a growth medium. Plant roots from some plant species are more effective competitors than others.
Cavity ringdown spectroscopy using mid-infrared quantum-cascade lasers (2000)

Cavity ringdown spectra of ammonia at 10 parts in 10(9) by volume (ppbv) and higher concentrations were recorded by use of a 16-mW continuous-wave quantum-casacde distributed-feedback laser at 8.5 mum whose wavelength was continuously temperature tuned over 15 nm. A sensitivity (noise-equivalent absorbance) of 3.4x10(-9) cm(-1) Hz(-1/2) was achieved for ammonia in nitrogen at standard temperature and pressure, which corresponds to a detection limit of 0.25 ppbv.
Photolytic and microbial degradation of 3,5,6-trichloro-2-pyridinol (1998)

Abstract The photolytic and microbial degradation of 3,5,6-trichloro-2-pyridinol (TCP), a metabolite of the insecticide chlorpyrifos and the herbicide triclopyr, has been investigated. TCP (80 mg/L) was decomposed to nondetectable levels within 2 h of ultraviolet irradiation. Release of 14CO2 and chloride ion was observed; however, approximately 60% of the initial radioactivity remained in the solution. Dichlorodihydroxypyridine isomers and reductive dechlorination products were found as intermediate products of TCP photolysis. It was proposed that both hydrolytic and reductive dechlorination occurred during photodegradation of TCP. Although TCP can be degraded via photolysis, many degradation products remained in the aqueous medium and only some of them, the reductive dechlorination products, can be mineralized by Pseudomonas sp. ATCC 700113. The degradation of the parent compound, TCP, by Pseudomonas sp. ATCC 700113 also appears to involve a reductive dechlorination mechanism. A consortium of microorganisms may be needed if a treatment process combining microbial and photolytic activity is to be used to remove TCP in industrial wastewater.
The Design of Potent, Selective and Drug‐Like RGD αvβ1 Small‐Molecule Inhibitors Derived from non‐RGD α4β1 Antagonists (2019)

Up to 45 % of deaths in developed nations can be attributed to chronic fibroproliferative diseases, highlighting the need for effective therapies. The RGD (Arg-Gly-Asp) integrin αvβ1 was recently investigated for its role in fibrotic disease, and thus warrants therapeutic targeting. Herein we describe the identification of non-RGD hit small-molecule αvβ1 inhibitors. We show that αvβ1 activity is embedded in a range of published α4β1 (VLA-4) ligands; we also demonstrate how a non-RGD integrin inhibitor (of α4β1 in this case) was converted into a potent non-zwitterionic RGD integrin inhibitor (of αvβ1 in this case). We designed urea ligands with excellent selectivity over α4β1 and the other αv integrins (αvβ3, αvβ5, αvβ6, αvβ8). In silico docking models and density functional theory (DFT) calculations aided the discovery of the lead urea series.