22,803 research outputs found

    Character-Level Language Modeling with Deeper Self-Attention

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    LSTMs and other RNN variants have shown strong performance on character-level language modeling. These models are typically trained using truncated backpropagation through time, and it is common to assume that their success stems from their ability to remember long-term contexts. In this paper, we show that a deep (64-layer) transformer model with fixed context outperforms RNN variants by a large margin, achieving state of the art on two popular benchmarks: 1.13 bits per character on text8 and 1.06 on enwik8. To get good results at this depth, we show that it is important to add auxiliary losses, both at intermediate network layers and intermediate sequence positions.Comment: 8 pages, 7 figure

    Numerical approximations for population growth model by Rational Chebyshev and Hermite Functions collocation approach: A comparison

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    This paper aims to compare rational Chebyshev (RC) and Hermite functions (HF) collocation approach to solve the Volterra's model for population growth of a species within a closed system. This model is a nonlinear integro-differential equation where the integral term represents the effect of toxin. This approach is based on orthogonal functions which will be defined. The collocation method reduces the solution of this problem to the solution of a system of algebraic equations. We also compare these methods with some other numerical results and show that the present approach is applicable for solving nonlinear integro-differential equations.Comment: 18 pages, 5 figures; Published online in the journal of "Mathematical Methods in the Applied Sciences

    Investigating the Spectrum of Biological Activity of Substituted Quinoline-2-Carboxamides and Their Isosteres

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    In this study, a series of thirty-five substituted quinoline-2-carboxamides and thirty-three substituted naphthalene-2-carboxamides were prepared and characterized. They were tested for their activity related to the inhibition of photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four mycobacterial species. N-Cycloheptylquinoline-2-carboxamide, N-cyclohexylquinoline-2-carboxamide and N-(2-phenylethyl)quinoline-2-carboxamide showed higher activity against M. tuberculosis than the standards isoniazid or pyrazinamide and 2-(pyrrolidin-1-ylcarbonyl)quinoline and 1-(2-naphthoyl)pyrrolidine expressed higher activity against M. kansasii and M. avium paratuberculosis than the standards isoniazid or pyrazinamide. The most effective antimycobacterial compounds demonstrated insignificant toxicity against the human monocytic leukemia THP-1 cell line. The PET-inhibiting activity expressed by IC50 value of the most active compound N-benzyl-2-naphthamide was 7.5 μmol/L. For all compounds, the structure-activity relationships are discussed

    Study of Aging and Production of Wine from Grape Fruit by Fermentation Process

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    Fermentation biotechnology is an important industrial process for the production of alcoholic beverages including wine. However, aging of wine is always an important issue during production. In present study a attempt has made to produce wine by fermentation process along with the assesment of aging of wine. In this experiment Grape fruit (jufeng) was used as a raw material and fermentation process was carried out with yeast (Saccharomyces cerevisiae) at 28 degrees C. During experiment growth of yeast cell, total solid contents and degree of liquor alcohol was considered critically. The various alcoholic compounds were analyzed with selective method of gas chromatography. Results obtained in the present study indicates that volume of all compounds like ethyl acetate, propyl alcohol, isobutyl alcohol, isoamyl acetate,isoamyl alcohol and ethyl formate was increased with the function of time during fermentation. While during aging process the contents of methyl acetate, ethyl acetate, isoamyl acetate and ethyl lactate were increased but isoamyl alcohol decreased. The levels of propyl alcohol and isobutyl alcohol fell after short period of time. However, no significant effects of aging process on methyl acetate, ethyl acetate, isobutyl alcohol, isoamyl alcohol and ethyl lactate (p\u3e0.05) were observed. Whereas significant effects of aging on the propyl alcohol and isoamyl acetate (p\u3c0.05) were observed

    N-Substituted 5-Amino-6-methylpyrazine-2,3-dicarbonitriles: Microwave-Assisted Synthesis and Biological Properties

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    In this work a series of 15 N-benzylamine substituted 5-amino-6-methyl-pyrazine-2,3-dicarbonitriles was prepared by the aminodehalogenation reactions using microwave assisted synthesis with experimentally set and proven conditions. This approach for the aminodehalogenation reaction was chosen due to its higher yields and shorter reaction times. The products of this reaction were characterized by IR, NMR and other analytical data. The compounds were evaluated for their antibacterial, antifungal and herbicidal activity. Compounds 3 (R = 3,4-Cl), 9 (R = 2-Cl) and 11 (R = 4-CF3) showed good antimycobacterial activity against Mycobacterium tuberculosis (MIC = 6.25 µg/mL). It was found that the lipophilicity is important for antimycobacterial activity and the best substitution on the benzyl moiety of the compounds is a halogen or trifluoromethyl group according to Craig’s plot. The activities against bacteria or fungi were insignificant. The presented compounds also inhibited photosynthetic electron transport in spinach chloroplasts and the IC50 values of the active compounds varied in the range from 16.4 to 487.0 µmol/L. The most active substances were 2 (R = 3-CF3), 3 (R = 3,4-Cl) and 11 (R = 4-CF3). A linear dependence between lipophilicity and herbicidal activity was observed

    Catalytic Wet Oxidation of Phenol by Hydrogen Peroxide over Pillared Clay Catalyst

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    Extrudates of Al-Fe Pillared Clay Catalyst Suitable for Packed-Bed Operations Are Evaluated for Wastewater Treatment Via a Wet Oxidation Process Employing Hydrogen Peroxide as the Oxidant. the Reaction Was Carried Out in a Semibatch Basket Reactor under Rather Mild Conditions. Operational Parameters Were Studied under the Following Conditions: Temperature from 25 to 90 °C, Atmospheric Pressure, Initial Phenol Concentration from 100 to 2000 Ppm of the Liquid Phase, Catalyst Loading from 0 to 10 G/L, and Input H2O2 Concentration from 0.15 to 0.6 Mol/L. under These Conditions, the Al-Fe Pillared Clay Catalyst Achieves a Total Elimination of Phenol and Significant Total Organic Carbon (TOC) Removal. This Catalyst Can Be Used Several Times Without Any Change in its Catalytic Properties, and Hence, It Would Be a Promising Catalyst for Industrial Wastewater Treatment. the Reaction Takes Place to a Significant Extent Both in the Liquid Phase and on the Catalyst Surface. Hence, Apparent Kinetic Models Were Developed by Formulating the Reaction Rate in Two Kinetic Expressions that Separately Consider the Homogeneous and Heterogeneous Contributions. using the Second-Order Approach for the Homogeneous Reaction and the Langmuir-Hinshelwood Approach for the Heterogeneous Reaction, the Developed Kinetic Models Describe Well the Removal of Phenol and the Formed Intermediate Carbon over the Entire Range of the Variables Studied

    Liquid Holdup and Pressure Drop in the Gas-Liquid Cocurrent Downflow Packed-Bed Reactor under Elevated Pressures

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    An Experimental Investigation of the Residence Time Distribution, Liquid Holdup, and Pressure Drop in a Gas-Liquid Downflow Packed Bed Reactor with Porous Particles Operated under Elevated Pressures is Presented. the Effects of the Two-Phase Flow Rates and Reactor Pressures on the External Liquid Holdup and Pressure Drop Are Discussed. a Mechanistic Model, Which Accounts for the Interaction between the Gas and Liquid Phases by Incorporating the Shear and Velocity Slip Factors between Phases, is Employed to Predict the External Liquid Holdup and Pressure Drop for the Experimentally Covered Flow Regime. the Involved Parameters, Such as Shear and Velocity Slip Factors and Ergun Single-Phase Flow Bed Constants, Are Calculated from the Correlations Developed Via Neural Network Regression. the Model\u27s Predictions and the Experimental Observations at Elevated Pressure Are Compared. © 2004 Elsevier Ltd. All Rights Reserved

    Catalytic Wet Air Oxidation of Phenol in Concurrent Downflow and Upflow Packed-Bed Reactors over Pillared Clay Catalyst

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    An Experimental Study is Presented for Comparing the Behavior of a Packed Bed Reactor in the Catalytic Liquid-Phase Oxidation of Aqueous Phenol with Two Modes of Operation, Downflow and Upflow. the Operating Parameters Investigated Included Temperature, Reactor Pressure, Gas Flowrate, Liquid Hourly Space Velocity and Feed Concentration. Because of the Completely Wetted Catalyst, the Upflow Reactor Generally Performs Better for High Pressures and Low Feed Concentrations When the Liquid Reactant Limitation Controls the Rate. the Interaction between the Reactor Hydrodynamics, Mass Transfer, and Reaction Kinetics is Discussed. for Both Operation Modes, Complete Phenol Removal and Significant Total Organic Carbon (TOC) Reduction Can Be Achieved at Rather Mild Conditions of Temperature (150-170°C) and Total Pressure (1.5-3.2 MPa). the Results Show that the Phenol and TOC Conversion Are Considerably Affected by the Temperature, While the Air Pressure Only Has Minor Influence. Total Elimination of TOC is Difficult Since Acetic Acid, as the Main Intermediate, is Resistant to Catalytic Wet Oxidation. All Tests Were Conducted over Extrudates of Fe-Al Pillared Clay Catalyst, Which is Stable and Maintains its Activity during the Long-Term Experimental Process. No Significant Catalyst Deactivation Due to Metal Ion Leaching and Polymer Deposition Was Detected. © 2004 Elsevier Ltd. All Rights Reserved

    Identification of PLXDC1 and PLXDC2 as the transmembrane receptors for the multifunctional factor PEDF.

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    Pigment Epithelium Derived Factor (PEDF) is a secreted factor that has broad biological activities. It was first identified as a neurotrophic factor and later as the most potent natural antiangiogenic factor, a stem cell niche factor, and an inhibitor of cancer cell growth. Numerous animal models demonstrated its therapeutic value in treating blinding diseases and diverse cancer types. A long-standing challenge is to reveal how PEDF acts on its target cells and the identities of the cell-surface receptors responsible for its activities. Here we report the identification of transmembrane proteins PLXDC1 and PLXDC2 as cell-surface receptors for PEDF. Using distinct cellular models, we demonstrate their cell type-specific receptor activities through loss of function and gain of function studies. Our experiments suggest that PEDF receptors form homooligomers under basal conditions, and PEDF dissociates the homooligomer to activate the receptors. Mutations in the intracellular domain can have profound effects on receptor activities
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