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2014

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Articles 11161 - 11190 of 12299

Full-Text Articles in Physical Sciences and Mathematics

Privacy-Preserving Ad-Hoc Equi-Join On Outsourced Data, Hwee Hwa Pang, Xuhua Ding Jan 2014

Privacy-Preserving Ad-Hoc Equi-Join On Outsourced Data, Hwee Hwa Pang, Xuhua Ding

Research Collection School Of Computing and Information Systems

In IT outsourcing, a user may delegate the data storage and query processing functions to a third-party server that is not completely trusted. This gives rise to the need to safeguard the privacy of the database as well as the user queries over it. In this article, we address the problem of running ad hoc equi-join queries directly on encrypted data in such a setting. Our contribution is the first solution that achieves constant complexity per pair of records that are evaluated for the join. After formalizing the privacy requirements pertaining to the database and user queries, we introduce a …

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Online Portfolio Selection: A Survey, Bin Li, Steven C. H. Hoi Jan 2014

Online Portfolio Selection: A Survey, Bin Li, Steven C. H. Hoi

Research Collection School Of Computing and Information Systems

Online portfolio selection is a fundamental problem in computational finance, which has been extensively studied across several research communities, including finance, statistics, artificial intelligence, machine learning, and data mining. This article aims to provide a comprehensive survey and a structural understanding of online portfolio selection techniques published in the literature. From an online machine learning perspective, we first formulate online portfolio selection as a sequential decision problem, and then we survey a variety of state-of-the-art approaches, which are grouped into several major categories, including benchmarks, Follow-the-Winner approaches, Follow-the-Loser approaches, Pattern-Matching--based approaches, and Meta-Learning Algorithms. In addition to the problem formulation …

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Atomic Layer Deposition Of Nanolaminate Structures Of Alternating Pbte And Pbse Thermoelectric Films, K. Zhang, A. D. Ramalingom Pillai, K. Bollenbach, D. Nminibapiel, W. Cao, H. Baumgart Jan 2014

Atomic Layer Deposition Of Nanolaminate Structures Of Alternating Pbte And Pbse Thermoelectric Films, K. Zhang, A. D. Ramalingom Pillai, K. Bollenbach, D. Nminibapiel, W. Cao, H. Baumgart

Electrical & Computer Engineering Faculty Publications

For this study PbTe and PbSe thin film nanolaminates have been prepared on silicon substrates with native oxide by Atomic Layer Deposition (ALD) using lead(II)bis(2,2,6,6-tetramethyl-3,5-heptanedionato) (Pb(C11H19O2)(2), (trimethylsilyl) telluride ((Me3Si)2Te) and bis-(triethyl silyl) selane ((Et3Si)2Se) as ALD precursors for lead, tellurium and selenium. The experimental evidence revealed the ALD growth of lead telluride and lead selenide followed the Vollmer-Weber island growth mode. We found a strong dependence of the nucleation process on the temperature. In this paper, we present the optimized conditions for growing PbTe …

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Optical And Hybrid Imaging And Processing For Big Data Problems, Khan Iftekharuddin, Abdul A. S. Awwal, S. Susan Young, Ghaleb M. Abdulla Jan 2014

Optical And Hybrid Imaging And Processing For Big Data Problems, Khan Iftekharuddin, Abdul A. S. Awwal, S. Susan Young, Ghaleb M. Abdulla

Electrical & Computer Engineering Faculty Publications

(First paragraph) The scientific community has been dealing with big data for a long time. Due to advancement in sensing, networking, and storage technology, other domains such as business, health, and social media followed. Data are considered the gold of the 21st century and are being collected, stored, and analyzed at a rapid pace. The amount of data being collected creates a compelling case for investing in hardware and software research to support generating even more data from new sensors and with better quality. It also creates a compelling case for investing in research and development of new hardware and …

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Validation Of Mipas Imk/Iaa V5r_O3_224 Ozone Profiles, A. Laeng, U. Grabowski, T. Von Clarmann, G. Stiller, N. Glatthor, M. Höpfner, S. Kellmann, M. Kiefer, A. Linden, S. Lossow, P. F. Bernath Jan 2014

Validation Of Mipas Imk/Iaa V5r_O3_224 Ozone Profiles, A. Laeng, U. Grabowski, T. Von Clarmann, G. Stiller, N. Glatthor, M. Höpfner, S. Kellmann, M. Kiefer, A. Linden, S. Lossow, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

We present the results of an extensive validation program of the most recent version of ozone vertical profiles retrieved with the IMK/IAA (Institute for Meteorology and Climate Research/Instituto de Astrofisica de Andalucia) MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) research level 2 processor from version 5 spectral level 1 data. The time period covered corresponds to the reduced spectral resolution period of the MIPAS instrument, i.e., January 2005-April 2012. The comparison with satellite instruments includes all post-2005 satellite limb and occultation sensors that have measured the vertical profiles of tropospheric and stratospheric ozone: ACE-FTS, GOMOS, HALOE, HIRDLS, MLS, OSIRIS, POAM, …

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A Distributed Consensus Algorithm For Decision Making In Service-Oriented Internet Of Things, Shancang Li, George Oikonomou, Theo Tryfonas, Thomas M. Chen, Li Da Xu Jan 2014

A Distributed Consensus Algorithm For Decision Making In Service-Oriented Internet Of Things, Shancang Li, George Oikonomou, Theo Tryfonas, Thomas M. Chen, Li Da Xu

Information Technology & Decision Sciences Faculty Publications

In a service-oriented Internet of things (IoT) deployment, it is difficult to make consensus decisions for services at different IoT edge nodes where available information might be insufficient or overloaded. Existing statistical methods attempt to resolve the inconsistency, which requires adequate information to make decisions. Distributed consensus decision making (CDM) methods can provide an efficient and reliable means of synthesizing information by using a wider range of information than existing statistical methods. In this paper, we first discuss service composition for the IoT by minimizing the multi-parameter dependent matching value. Subsequently, a cluster-based distributed algorithm is proposed, whereby consensuses are …

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Synthesis And Characterization Of Ph Responsive D-Glucosamine Based Molecular Gelators, Navneet Goyal, Hari P.R. Mangunuru, Bargav Parikh, Sonu Shrestha, Guijun Wang Jan 2014

Synthesis And Characterization Of Ph Responsive D-Glucosamine Based Molecular Gelators, Navneet Goyal, Hari P.R. Mangunuru, Bargav Parikh, Sonu Shrestha, Guijun Wang

Chemistry & Biochemistry Faculty Publications

Small molecular gelators are a class of compounds with potential applications for soft biomaterials. Low molecular weight hydrogelators are especially useful for exploring biomedical applications. Previously, we found that 4,6-O-benzylidene acetal protected D-glucose and D-glucosamine are well-suited as building blocks for the construction of low molecular weight gelators. To better understand the scope of D-glucosamine derivatives as gelators, we synthesized and screened a novel class of N-acetylglucosamine derivatives with a p-methoxybenzylidene acetal protective group. This modification did not exert a negative influence on the gelation. On the contrary, it actually enhanced the gelation tendency for many derivatives. The …

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Middle Atmospheric Changes Caused By The January And March 2012 Solar Proton Events, C. H. Jackman, C. E. Randall, V. L. Harvey, S. Wang, E. L. Fleming, M. López-Puertas, B. Funke, P. F. Bernath Jan 2014

Middle Atmospheric Changes Caused By The January And March 2012 Solar Proton Events, C. H. Jackman, C. E. Randall, V. L. Harvey, S. Wang, E. L. Fleming, M. López-Puertas, B. Funke, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

The recent 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic solar protons produced considerable ionization of the neutral atmosphere as well as HOx (H, OH, HO2) and NOx (N, NO, NO2). We compute a NOx production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which places these SPE periods among the 12 largest in the past 50 yr. Aura Microwave Limb Sounder (MLS) …

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Drift Corrected Trends And Periodic Variations In Mipas Imk/Iaa Ozone Measurements, E. Eckert, T. Von Clarmann, M. Kiefer, G. P. Stiller, S. Lossow, N. Glatthor, D. A. Degenstein, L. Froidevaux, S. Godin-Beekmann, T. Leblanc, S. Mcdermid, M. Pastel, W. Steinbrcht, D.P.J. Swart, K. A. Walker, P. F. Bernath Jan 2014

Drift Corrected Trends And Periodic Variations In Mipas Imk/Iaa Ozone Measurements, E. Eckert, T. Von Clarmann, M. Kiefer, G. P. Stiller, S. Lossow, N. Glatthor, D. A. Degenstein, L. Froidevaux, S. Godin-Beekmann, T. Leblanc, S. Mcdermid, M. Pastel, W. Steinbrcht, D.P.J. Swart, K. A. Walker, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

Drifts, trends and periodic variations were calculated from monthly zonally averaged ozone profiles. The ozone profiles were derived from level-1b data of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) by means of the scientific level-2 processor run by the Karlsruhe Institute of Technology (KIT), Institute for Meteorology and Climate Research (IMK). All trend and drift analyses were performed using a multilinear parametric trend model which includes a linear term, several harmonics with period lengths from 3 to 24 months and the quasi-biennial oscillation (QBO). Drifts at 2-sigma significance level were mainly negative for ozone relative to Aura MLS and …

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Spectrometric Monitoring Of Atmospheric Carbon Tetrafluoride (Cf4) Above The Jungfraujoch Station Since 1989: Evidence Of Continued Increase But At A Slowing Rate, E. Mahieu, R. Zander, G. C. Toon, M. K. Vollmer, S. Reimann, J. Muhle, W. Bader, B. Bovy, B. Lejune, C. Servais, P. F. Bernath Jan 2014

Spectrometric Monitoring Of Atmospheric Carbon Tetrafluoride (Cf4) Above The Jungfraujoch Station Since 1989: Evidence Of Continued Increase But At A Slowing Rate, E. Mahieu, R. Zander, G. C. Toon, M. K. Vollmer, S. Reimann, J. Muhle, W. Bader, B. Bovy, B. Lejune, C. Servais, P. F. Bernath

Chemistry & Biochemistry Faculty Publications

The long-term evolution of the vertical column abundance of carbon tetrafluoride (CF4) above the high-altitude Jungfraujoch station (Swiss Alps, 46.5 ° N, 8.0 ° E, 3580 ma.s.l.) has been derived from the spectrometric analysis of Fourier transform infrared solar spectra recorded at that site between 1989 and 2012. The investigation is based on a multi-microwindow approach, two encompassing pairs of absorption lines belonging to the R-branch of the strong ν3 band of CF4 centered at 1283 cm-1, and two additional ones to optimally account for weak but overlapping HNO3 interferences. The analysis reveals …

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Ch In Stellar Atmospheres: An Extensive Linelist, T. Masseron, B. Plez, S. Van Eck, R. Colin, I. Daoutidis, M. Godefroid, P.-F. Coheur, P. Bernath, A. Jorissen, N. Christleib Jan 2014

Ch In Stellar Atmospheres: An Extensive Linelist, T. Masseron, B. Plez, S. Van Eck, R. Colin, I. Daoutidis, M. Godefroid, P.-F. Coheur, P. Bernath, A. Jorissen, N. Christleib

Chemistry & Biochemistry Faculty Publications

The advent of high-resolution spectrographs and detailed stellar atmosphere modelling has strengthened the need for accurate molecular data. Carbon-enhanced metal-poor (CEMP) stars spectra are interesting objects with which to study transitions from the CH molecule. We combine programs for spectral analysis of molecules and stellar-radiative transfer codes to build an extensive CH linelist, including predissociation broadening as well as newly identified levels. We show examples of strong predissociation CH lines in CEMP stars, and we stress the important role played by the CH features in the Bond-Neff feature depressing the spectra of barium stars by as much as 0.2 mag …

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A Database Of Water Transitions From Experiment And Theory (Iupac Technical Report), Jonathan Tennyson, Peter F. Bernath, Linda R. Brown, Alain Campargue, Attila G. Császár, Ludovic Daumont Jan 2014

A Database Of Water Transitions From Experiment And Theory (Iupac Technical Report), Jonathan Tennyson, Peter F. Bernath, Linda R. Brown, Alain Campargue, Attila G. Császár, Ludovic Daumont

Chemistry & Biochemistry Faculty Publications

The report and results of an IUPAC Task Group (TG) formed in 2004 on "A Database of Water Transitions from Experiment and Theory" (Project No. 2004-035-1-100) are presented. Energy levels and recommended labels involving exact and approximate quantum numbers for the main isotopologues of water in the gas phase, H216O, H2180, H217O, HD16O, HD18O, HD17O, D216O, D218O, and D217O, are determined from measured transition frequencies. The transition frequencies and energy levels are validated using first-principles nuclear …

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Recommended Isolated-Line Profile For Representing High-Resolution Spectroscopic Transitions (Iupac Technical Report), Jonathan Tennyson, Peter F. Bernath, Alain Campargue, Attila G. Császár, Ludovic Daumont, Robert R. Gamache, Joseph T. Hodges, Daniel Lisak, Olga V. Naumenko, Laurence S. Rothman Jan 2014

Recommended Isolated-Line Profile For Representing High-Resolution Spectroscopic Transitions (Iupac Technical Report), Jonathan Tennyson, Peter F. Bernath, Alain Campargue, Attila G. Császár, Ludovic Daumont, Robert R. Gamache, Joseph T. Hodges, Daniel Lisak, Olga V. Naumenko, Laurence S. Rothman

Chemistry & Biochemistry Faculty Publications

The report of an IUPAC Task Group, formed in 2011 on "Intensities and line shapes in high-resolution spectra of water isotopologues from experiment and theory" (Project No. 2011-022-2-100), on line profiles of isolated high-resolution rotational-vibrational transitions perturbed by neutral gas-phase molecules is presented. The well-documented inadequacies of the Voigt profile (VP), used almost universally by databases and radiative-transfer codes, to represent pressure effects and Doppler broadening in isolated vibrational-rotational and pure rotational transitions of the water molecule have resulted in the development of a variety alternative line-profile models. These models capture more of the physics of the influence of pressure …

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Compositions And Constituents Of Freshwater Dissolved Organic Matter Isolated By Reverse Osmosis, Yulong Zhang, Wen Huang, Jingdong Mao Jan 2014

Compositions And Constituents Of Freshwater Dissolved Organic Matter Isolated By Reverse Osmosis, Yulong Zhang, Wen Huang, Jingdong Mao

Chemistry & Biochemistry Faculty Publications

Dissolved organic matter (DOM) from riverine and lacustrine water was isolated using a reverse osmosis (RO) system. Solid-state 13C nuclear magnetic resonance (13C NMR) was used to quantitatively evaluate the compositions and constituents of DOM, which are compared with previous investigations on marine DOM. Results indicated that concentration factor (CF) was a key metric controlling yield and sorption of DOM on the RO system. The sorption was likely non-selective, based on the 13C NMR and δ13C analyses. Carbohydrates and lipids accounted for 25.0–41.5% and 30.2–46.3% of the identifiable DOM, followed by proteins (18.2–19.8%) and …

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Wavelength And Temperature-Dependent Apparent Quantum Yields For Photochemical Formation Of Hydrogen Peroxide In Seawater, David J. Kieber, Gary W. Miller, Patrick J. Neale, Kenneth Mopper Jan 2014

Wavelength And Temperature-Dependent Apparent Quantum Yields For Photochemical Formation Of Hydrogen Peroxide In Seawater, David J. Kieber, Gary W. Miller, Patrick J. Neale, Kenneth Mopper

Chemistry & Biochemistry Faculty Publications

Wavelength and temperature-dependent apparent quantum yields (AQYs) were determined for the photochemical production of hydrogen peroxide using seawater obtained from coastal and oligotrophic stations in Antarctica, the Pacific Ocean at Station ALOHA, the Gulf of Mexico, and at several sites along the East Coast of the United States. For all samples, AQYs decreased exponentially with increasing wavelength at 25 °C, ranging from 4.6 × 10−4 to 10.4 × 10−4 at 290 nm to 0.17 × 10−4 to 0.97 × 10−4 at 400 nm. AQYs for different seawater samples were remarkably similar irrespective of expected differences in the composition and concentrations …

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Satellite Observations Of Stratospheric Carbonyl Fluoride, J. J. Harrison, M. P. Chipperfield, A. Dudhia, S. Cai, S. Dhomse, C. D. Boone, Peter F. Bernath Jan 2014

Satellite Observations Of Stratospheric Carbonyl Fluoride, J. J. Harrison, M. P. Chipperfield, A. Dudhia, S. Cai, S. Dhomse, C. D. Boone, Peter F. Bernath

Chemistry & Biochemistry Faculty Publications

The vast majority of emissions of fluorine-containing molecules are anthropogenic in nature, e.g. chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and hydrofluorocarbons (HFCs). These molecules slowly degrade in the atmosphere, leading to the formation of HF, COF2, and COClF, which are the main fluorine-containing species in the stratosphere. Ultimately both COF2 and COClF further degrade to form HF, an almost permanent reservoir of stratospheric fluorine due to its extreme stability. Carbonyl fluoride (COF2) is the second-most abundant stratospheric "inorganic" fluorine reservoir, with main sources being the atmospheric degradation of CFC-12 (CCl2F2), HCFC-22 (CHF2Cl), and CFC-113 (CF2ClCFCl2).

This work reports the first global distributions …

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A Molecular-Level Approach For Characterizing Water-Insoluble Components Of Ambient Organic Aerosol Particulates Using Ultrahigh-Resolution Mass Spectrometry, A. S. Willoughby, A. S. Wozniak, Patrick G. Hatcher Jan 2014

A Molecular-Level Approach For Characterizing Water-Insoluble Components Of Ambient Organic Aerosol Particulates Using Ultrahigh-Resolution Mass Spectrometry, A. S. Willoughby, A. S. Wozniak, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The chemical composition of organic aerosols in the atmosphere is strongly influenced by human emissions. The effect these have on the environment, human health, and climate change is determined by the molecular nature of these chemical species. The complexity of organic aerosol samples limits the ability to study the chemical composition, and therefore the associated properties and the impacts they have. Many studies have addressed the watersoluble fraction of organic aerosols and have had much success in identifying specific molecular formulas for thousands of compounds present. However, little attention is given to the water-insoluble portion, which can contain most of …

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Distinguishing Molecular Characteristics Of Aerosol Water Soluble Organic Matter From The 2011 Trans-North Atlantic Us Geotraces Cruise, A. S. Wozniak, A. S. Willoughby, S. C. Gurganus, Patrick G. Hatcher Jan 2014

Distinguishing Molecular Characteristics Of Aerosol Water Soluble Organic Matter From The 2011 Trans-North Atlantic Us Geotraces Cruise, A. S. Wozniak, A. S. Willoughby, S. C. Gurganus, Patrick G. Hatcher

Chemistry & Biochemistry Faculty Publications

The molecular characteristics of aerosol organic matter (OM) determines to a large extent its impacts on the atmospheric radiative budget and ecosystem function in terrestrial and aquatic environments, yet the OM molecular details of aerosols from different sources are not well established. Aerosol particulate samples with North American-influenced, North African-influenced, and marine (minimal recent continental influence) air mass back trajectories were collected as part of the 2011 trans-North Atlantic US GEOTRACES cruise and analyzed for their water soluble OM (WSOM) molecular characteristics using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry. Principal component analysis (PCA) separated the samples into …

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On Empirical Validation Of Compactness Measures For Electoral Redistricting And Its Significance For Application Of Models In The Social Sciences, Christine Chou, Steven O. Kimbrough, Frederic H. Murphy, John Sullivan-Fedock, C. Jason Woodard Jan 2014

On Empirical Validation Of Compactness Measures For Electoral Redistricting And Its Significance For Application Of Models In The Social Sciences, Christine Chou, Steven O. Kimbrough, Frederic H. Murphy, John Sullivan-Fedock, C. Jason Woodard

Research Collection School Of Computing and Information Systems

Use of optimization models in science and policy applications is often problematic because the best available models are very inaccurate representations of the originating problems. Such is the case with electoral districting models, for which there exist no generally accepted measures of compactness, in spite of many proposals and much analytical study. This article reports on an experimental investigation of subjective judgments of compactness for electoral districts. The experiment draws on a unique database of 116 distinct, legally valid districting plans for the Philadelphia City Council, discovered with evolutionary computation. Subjects in the experiment displayed, in the aggregate, remarkable agreement …

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Spectrophotometric Determination Of Molybdenum Using Surfactant-Mediated Liquid--Liquid Extraction, Rameshwar Dass, Jitander Kumar Kapoor, Sunita Gambhir Jan 2014

Spectrophotometric Determination Of Molybdenum Using Surfactant-Mediated Liquid--Liquid Extraction, Rameshwar Dass, Jitander Kumar Kapoor, Sunita Gambhir

Turkish Journal of Chemistry

A new spectrophotometric method has been developed for determination of molybdenum using surfactant-mediated liquid--liquid extraction. Molybdenum(V) obtained by ascorbic acid reduction in 2.5 M H_2SO_4 reacted spontaneously with thiocyanate and cetyl trimethyl ammonium bromide (CTAB), forming an intense orange yellow complex that was extracted quantitatively into 1,2-dichloroethane and absorbed at 460 nm. The absorbance of the extract was found to be stable for more than 24 h. Beer's law was obeyed over the concentration range 0.1--4.2 \mu g Mo mL^{-1} of the extract. The linear range for an accurate determination was found to be 1.2--2.6 \mu g Mo mL^{-1}. The …

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Application Of Guanidine And Its Salts In Multicomponent Reactions, Mahshid Rahimifard, Ghodsi Mohammadi Ziarani, Boshra Malekzadeh Lashkariani Jan 2014

Application Of Guanidine And Its Salts In Multicomponent Reactions, Mahshid Rahimifard, Ghodsi Mohammadi Ziarani, Boshra Malekzadeh Lashkariani

Turkish Journal of Chemistry

This review gives an overview of the application of guanidine and its salts in multicomponent reactions. It can act as a catalyst or solvent for multicomponent reactions or as a reagent for synthesis of substituted diazines, triazines, and macroheterocycles by multicomponent reactions.

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Preparation And Characterization Of Nonmetal Promoter Modified Cuznal Catalysts For Higher Alcohol From Synthesis Gas Through Complete Liquid Phase Method, Shirui Yu, Xiaodong Wang, Wei Huang Jan 2014

Preparation And Characterization Of Nonmetal Promoter Modified Cuznal Catalysts For Higher Alcohol From Synthesis Gas Through Complete Liquid Phase Method, Shirui Yu, Xiaodong Wang, Wei Huang

Turkish Journal of Chemistry

A complete liquid phase technology and a function regulator were applied to prepare CuZnAl catalysts for higher alcohol synthesis. Characterizations showed that the introduction of the function regulator can change the reduction ability of copper oxides and the surface basicity of catalysts. Activity tests indicated that the selectivity of higher alcohol is high when considerable medium-strong basicity and the synergistic effects of copper ion and metal copper exist on the catalytic surface. The optimized modified CuZnAl catalyst without any metal additives provides a CO conversion of 28.9%, C_{2+}OH selectivity of up to 42.8%, and hydrocarbon selectivity of 2.5%, with a …

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Crystal Growth Morphology Of Magnesium Hydroxide, Jiansong Wu, Juan Du, Yi-Min Gao Jan 2014

Crystal Growth Morphology Of Magnesium Hydroxide, Jiansong Wu, Juan Du, Yi-Min Gao

Turkish Journal of Chemistry

In this paper, the formation process of magnesium hydroxide unit cells, as well as the structural characteristics and growth morphology of magnesium hydroxide, is discussed from the perspective of growth units. The growth process of the hexagonal structure of the magnesium hydroxide is as follows: the growth units are first incorporated into a larger hexagonal dimension unit on the same plane, and then the hexagonal layers connect to each other in the z-axis direction for the hexagonal magnesium hydroxide unit cell. The results of the study show that the model of anion coordination polyhedron growth units may be reasonably deduced …

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Te(Ii)-Induced Heterocyclization Of 1,2-Alkadienephosphonates, Dobromir Dimitrov Enchev Jan 2014

Te(Ii)-Induced Heterocyclization Of 1,2-Alkadienephosphonates, Dobromir Dimitrov Enchev

Turkish Journal of Chemistry

The reactivity of some 1,2-alkadienephosphonates towards phenyltelluryl halides was investigated. A plausible mechanism of the reaction is discussed.

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Novel N-Acyl/Aroyl-2-(5-Phenyl-2h-Tetrazol-2-Yl)Acetohydrazides: Synthesis And Characterization, Aamer Saeed, Majid Hussain, Muhammad Qasim Jan 2014

Novel N-Acyl/Aroyl-2-(5-Phenyl-2h-Tetrazol-2-Yl)Acetohydrazides: Synthesis And Characterization, Aamer Saeed, Majid Hussain, Muhammad Qasim

Turkish Journal of Chemistry

A number of novel N-acyl/aroyl-2-(5-phenyl-2H-tetrazol-2-yl)acetohydrazides (4a--j) of biological interest were efficiently synthesized by treating 2-(5-phenyl-2H-tetrazole-2-yl)acetohydrazide (3) with a variety of aroyl/hetero- cyclyl or alkanoyl chlorides. FTIR, ^1H NMR, ^{13}C NMR, GC-MS, and elemental analyses data confirmed the structures assigned to the newly synthesized compounds.

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Synthesis And Phase Transition Studies Of New Dimer Compounds Connected To A 1,3-Dimethylbarbituric Acid Core, Abdulkarim-Talaq Mohammad, Guan-Yeow Yeap, Hasnah Osman Jan 2014

Synthesis And Phase Transition Studies Of New Dimer Compounds Connected To A 1,3-Dimethylbarbituric Acid Core, Abdulkarim-Talaq Mohammad, Guan-Yeow Yeap, Hasnah Osman

Turkish Journal of Chemistry

A series of dimeric unsymmetrical liquid crystals derived from heterocyclic 1,3-dimethylbarbituric acid exhibiting smectic A and nematic phase are reported. All compounds were prepared by the condensation of 4'-(R-(4-formylphenoxy)butoxy)biphenyl-4-carboxylate with 1,3-dimethylbarbituric acid in ethanol. The mesomorphic properties were investigated by DSC and POM, where the type of phase depends on the length of spacer alkoxy chains and the length of the terminal chain. While the SmA phase was observed upon the heating and cooling run when the spacer alkoxy chains carbon numbers increased (n = 6), the N phase was observed when the length of spacer alkoxy chains increased (n …

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Investigation Of The Adsorption Kinetics Of Methylene Blue Onto Cotton Wastes, Bi̇lal Acemi̇oğlu, Murat Ertaş, Mehmet Hakki Alma, Mustafa Usta Jan 2014

Investigation Of The Adsorption Kinetics Of Methylene Blue Onto Cotton Wastes, Bi̇lal Acemi̇oğlu, Murat Ertaş, Mehmet Hakki Alma, Mustafa Usta

Turkish Journal of Chemistry

Cotton stalk (CS), cotton waste (CW), and cotton dust (CD), which are cotton wastes, were used as adsorbents to study the adsorption kinetics of methylene blue from aqueous solution. Kinetics of the batch adsorption experiment was investigated according to the pseudo-first order, the pseudo-second order, and the intraparticle diffusion models used commonly in the literature. The effects of the initial concentration, solution pH, and temperature on kinetic parameters (adsorption rate constant, initial adsorption rate, equilibrium adsorption capacity, etc.) were studied. The results showed that the adsorption process was well fitted to the pseudo-second order model for all adsorbents. The activation …

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Facile Synthesis Of 5-Bromotropono[C]-Fused Pyrazoles And Isoxazole, Yang Li, Liangyu Xu, Wentao Gao Jan 2014

Facile Synthesis Of 5-Bromotropono[C]-Fused Pyrazoles And Isoxazole, Yang Li, Liangyu Xu, Wentao Gao

Turkish Journal of Chemistry

A facile synthesis of a series of new 5-bromotropono[c]pyrazole derivatives (3 and 10--15) as well as 5-bromotropono[c]isoxazole (17) is described, involving a condensation reaction of 3-acetyl-5-bromotropolone (1) with hydrazine monohydrate (2), arylhydrazine hydrochlorides (4--9), and hydroxylamine hydrochloride (16), respectively. All the synthesized compounds were obtained in good yields of 56%--77% and their structures were characterized by spectral data and HRMS.

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Solvent Extraction Of Praseodymium(Iii) From Acidic Nitrate Medium Using Cyanex 921 And Cyanex 923 As Extractants In Kerosene, Nandita Panda, Nihar Bala Devi, Sujata Mishra Jan 2014

Solvent Extraction Of Praseodymium(Iii) From Acidic Nitrate Medium Using Cyanex 921 And Cyanex 923 As Extractants In Kerosene, Nandita Panda, Nihar Bala Devi, Sujata Mishra

Turkish Journal of Chemistry

Solvent extraction of praseodymium(III) from acidic nitrate medium by the neutral organophosphorous extractants Cyanex 921 and Cyanex 923 in kerosene was studied. The effects of various parameters like equilibration time, nitric acid concentration, nitrate ion concentration, extractant concentration, temperature, and nature of diluents on the extraction behavior of Pr(III) were investigated. The extraction of 0.001 M Pr(III) was quantitative (93%) from the aqueous phase containing 0.001 M HNO_3 and 0.1 M KNO_3 using 0.5 M Cyanex 921/1 M Cyanex 923. On the basis of slope analysis, the compositions of the extracted species were formulated as Pr(NO_3)_3.2Cyanex 921 and Pr (NO_3)_3.Cyanex …

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In Vitro Effects Of Pesticide Exposure On The Activity Of The Paraoxonase-1 Enzyme From Sheep Liver Microsomes, Büşra Cebeci̇, Zuhal Alim, Şükrü Beydemi̇r Jan 2014

In Vitro Effects Of Pesticide Exposure On The Activity Of The Paraoxonase-1 Enzyme From Sheep Liver Microsomes, Büşra Cebeci̇, Zuhal Alim, Şükrü Beydemi̇r

Turkish Journal of Chemistry

The organophosphate target enzyme paraoxonase-1 (PON1) has been extensively studied in toxicology. Pesticides are organophosphate compounds that are commonly used in agriculture. They are also used as nerve gases, such as sarin and soman. Therefore, the effects of these compounds on enzymatic activity are well known. In the present study, we investigated the in vitro effects of fenoxaprop-p-ethyl, lambda cyhalothrin, imidacloprid, and dichlorvos pesticides on sheep liver microsomal PON1. The enzyme was purified approximately 141-fold with a specific activity of 1822.22 EU/mg proteins. The pesticides inhibited sheep liver PON1 in vitro, and the IC_{50} values for these compounds were 0.0103, …

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