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Sample records for acid base analog

  1. Nucleic Acid Base Analog FRET-Pair Facilitating Detailed Structural Measurements in Nucleic Acid Containing Systems

    DEFF Research Database (Denmark)

    Börjesson, Karl; Preus, Søren; El-Sagheer, Afaf

    2009-01-01

    distances covering up to more than one turn of the DNA duplex. Importantly, we show that the rigid stacking of the two base analogs, and consequently excellent control of their exact positions and orientations, results in a high control of the orientation factor and hence very distinct FRET changes...... as the number of bases separating tCO and tC(nitro) is varied. A set of DNA strands containing the FRET-pair at wisely chosen locations will, thus, make it possible to accurately distinguish distance- from orientation-changes using FRET. In combination with the good nucleobase analog properties, this points...... toward detailed studies of the inherent dynamics of nucleic acid structures. Moreover, the placement of FRET-pair chromophores inside the base stack will be a great advantage in studies where other (biomacro)molecules interact with the nucleic acid. Lastly, our study gives possibly the first truly solid...

  2. Using Conceptual Change Texts with Analogies for Misconceptions in Acids and Bases

    Science.gov (United States)

    Cetingul, Ipek; Geban, Omer

    2011-01-01

    This study was conducted to explore the effectiveness of conceptual change oriented instruction over traditional instruction on students' understanding of acids and bases concept. Besides, effects of gender difference and science process skills on students' understanding of acids and bases were also investigated. Analysis of the results showed…

  3. Using Conceptual Change Texts with Analogies for Misconceptions in Acids and Bases

    Science.gov (United States)

    Cetingul, Ipek; Geban, Omer

    2011-01-01

    This study was conducted to explore the effectiveness of conceptual change oriented instruction over traditional instruction on students' understanding of acids and bases concept. Besides, effects of gender difference and science process skills on students' understanding of acids and bases were also investigated. Analysis of the results showed…

  4. Comparative acid-base properties of the surface of components of the CdTe-ZnS system in series of substitutional solid solutions and their analogs

    Science.gov (United States)

    Kirovskaya, I. A.; Kasatova, I. Yu.

    2011-07-01

    The acid-base properties of the surface of solid solutions and binary components of the CdTe-ZnS system are studied by hydrolytic adsorption, nonaqueous conductometric titration, mechanochemistry, IR spectroscopy, and Raman scattering spectroscopy. The strength, nature, and concentration of acid centers on the original surface and that exposed to CO are determined. The changes in acid-base properties in dependence on the composition of the system under investigation in the series of CdB6, ZnB6 analogs are studied.

  5. Amino acid analogs for tumor imaging

    Science.gov (United States)

    Goodman, M.M.; Shoup, T.

    1998-09-15

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [{sup 18}F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an {alpha}-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of {alpha}-aminoisobutyric acid.

  6. Amino acid analogs for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, Mark M. (Atlanta, GA); Shoup, Timothy (Decatur, GA)

    1998-09-15

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ›.sup.18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an .alpha.-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of .alpha.-aminoisobutyric acid.

  7. Amino acid analogs for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, Mark M. (Atlanta, GA); Shoup, Timothy (Decatur, GA)

    1998-10-06

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is ›.sup.18 F!-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an .alpha.-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of .alpha.-aminoisobutyric acid.

  8. Amino acid analogs for tumor imaging

    Energy Technology Data Exchange (ETDEWEB)

    Goodman, M.M.; Shoup, T.

    1998-10-06

    The invention provides novel amino acid compounds of use in detecting and evaluating brain and body tumors. These compounds combine the advantageous properties of 1-amino-cycloalkyl-1-carboxylic acids, namely, their rapid uptake and prolonged retention in tumors with the properties of halogen substituents, including certain useful halogen isotopes including fluorine-18, iodine-123, iodine-125, iodine-131, bromine-75, bromine-76, bromine-77 and bromine-82. In one aspect, the invention features amino acid compounds that have a high specificity for target sites when administered to a subject in vivo. Preferred amino acid compounds show a target to non-target ratio of at least 5:1, are stable in vivo and substantially localized to target within 1 hour after administration. An especially preferred amino acid compound is [{sup 18}F]-1-amino-3-fluorocyclobutane-1-carboxylic acid (FACBC). In another aspect, the invention features pharmaceutical compositions comprised of an {alpha}-amino acid moiety attached to either a four, five, or a six member carbon-chain ring. In addition, the invention features analogs of {alpha}-aminoisobutyric acid.

  9. Use of Nucleic Acid Analogs for the Study of Nucleic Acid Interactions

    Directory of Open Access Journals (Sweden)

    Shu-ichi Nakano

    2011-01-01

    Full Text Available Unnatural nucleosides have been explored to expand the properties and the applications of oligonucleotides. This paper briefly summarizes nucleic acid analogs in which the base is modified or replaced by an unnatural stacking group for the study of nucleic acid interactions. We also describe the nucleoside analogs of a base pair-mimic structure that we have examined. Although the base pair-mimic nucleosides possess a simplified stacking moiety of a phenyl or naphthyl group, they can be used as a structural analog of Watson-Crick base pairs. Remarkably, they can adopt two different conformations responding to their interaction energies, and one of them is the stacking conformation of the nonpolar aromatic group causing the site-selective flipping of the opposite base in a DNA double helix. The base pair-mimic nucleosides can be used to study the mechanism responsible for the base stacking and the flipping of bases out of a nucleic acid duplex.

  10. Kinetics and Mechanisms of the Acid-base Reaction Between NH3 and HCOOH in Interstellar Ice Analogs

    Science.gov (United States)

    Bergner, Jennifer B.; Öberg, Karin I.; Rajappan, Mahesh; Fayolle, Edith C.

    2016-10-01

    Interstellar complex organic molecules are commonly observed during star formation, and are proposed to form through radical chemistry in icy grain mantles. Reactions between ions and neutral molecules in ices may provide an alternative cold channel to complexity, as ion-neutral reactions are thought to have low or even no-energy barriers. Here we present a study of the kinetics and mechanisms of a potential ion-generating, acid-base reaction between NH3 and HCOOH to form the salt NH{}4+HCOO-. We observe salt growth at temperatures as low as 15 K, indicating that this reaction is feasible in cold environments. The kinetics of salt growth are best fit by a two-step model involving a slow “pre-reaction” step followed by a fast reaction step. The reaction energy barrier is determined to be 70 ± 30 K with a pre-exponential factor 1.4 ± 0.4 × 10-3 s-1. The pre-reaction rate varies under different experimental conditions and likely represents a combination of diffusion and orientation of reactant molecules. For a diffusion-limited case, the pre-reaction barrier is 770 ± 110 K with a pre-exponential factor of ˜7.6 × 10-3 s-1. Acid-base chemistry of common ice constituents is thus a potential cold pathway to generating ions in interstellar ices.

  11. Kinetics and mechanisms of the acid-base reaction between NH$_3$ and HCOOH in interstellar ice analogs

    CERN Document Server

    Bergner, Jennifer B; Rajappan, Mahesh; Fayolle, Edith C

    2016-01-01

    Interstellar complex organic molecules (COMs) are commonly observed during star formation, and are proposed to form through radical chemistry in icy grain mantles. Reactions between ions and neutral molecules in ices may provide an alternative cold channel to complexity, as ion-neutral reactions are thought to have low or even no energy barriers. Here we present a study of a the kinetics and mechanisms of a potential ion-generating acid-base reaction between NH$_{3}$ and HCOOH to form the salt NH$_{4}^{+}$HCOO$^{-}$. We observe salt growth at temperatures as low as 15K, indicating that this reaction is feasible in cold environments. The kinetics of salt growth are best fit by a two-step model involving a slow "pre-reaction" step followed by a fast reaction step. The reaction energy barrier is determined to be 70 $\\pm$ 30K with a pre-exponential factor 1.4 $\\pm$ 0.4 x 10$^{-3}$ s$^{-1}$. The pre-reaction rate varies under different experimental conditions and likely represents a combination of diffusion and or...

  12. Ferrocenylaniline based amide analogs of methoxybenzoic acids: Synthesis, structural characterization and butyrylcholinesterase (BChE) inhibition studies

    Science.gov (United States)

    Altaf, Ataf Ali; Kausar, Samia; Hamayun, Muhammad; Lal, Bhajan; Tahir, Muhammad Nawaz; Badshah, Amin

    2017-10-01

    Three new ferrocene based amides were synthesized with slight structural difference. The general formula of the amides is C5H5FeC5H4C6H4NHCOC6H4(OCH3). The synthesized compounds were characterized by instrumental techniques like elemental analysis, FTIR and NMR spectroscopy. Structure of the two compounds was also studied by single crystal X-rays diffraction analysis. Structural studies provide the evidence that pMeO (one of the synthesized compounds) is an example of amides having no intermolecular hydrogen bonding in solid structure. In the BChE inhibition assay, compound (oMeO) having strong intermolecular force in the solid structure is less active than the compound (pMeO) with weak intermolecular forces in the solid structure. The docking studies proved that hydrogen bonding between inhibitor and BChE enzyme is of more importance for the activity, rather than intermolecular hydrogen bonding in the solid structure of inhibitor.

  13. Orbital evidence for clay and acidic sulfate assemblages on Mars based on mineralogical analogs from Rio Tinto, Spain

    Science.gov (United States)

    Kaplan, Hannah H.; Milliken, Ralph E.; Fernández-Remolar, David; Amils, Ricardo; Robertson, Kevin; Knoll, Andrew H.

    2016-09-01

    Outcrops of hydrated minerals are widespread across the surface of Mars, with clay minerals and sulfates being commonly identified phases. Orbitally-based reflectance spectra are often used to classify these hydrated components in terms of a single mineralogy, although most surfaces likely contain multiple minerals that have the potential to record local geochemical conditions and processes. Reflectance spectra for previously identified deposits in Ius and Melas Chasma within the Valles Marineris, Mars, exhibit an enigmatic feature with two distinct absorptions between 2.2 and 2.3 μm. This spectral 'doublet' feature is proposed to result from a mixture of hydrated minerals, although the identity of the minerals has remained ambiguous. Here we demonstrate that similar spectral doublet features are observed in airborne, field, and laboratory reflectance spectra of rock and sediment samples from Rio Tinto, Spain. Combined visible-near infrared reflectance spectra and X-ray diffraction measurements of these samples reveal that the doublet feature arises from a mixture of Al-phyllosilicate (illite or muscovite) and jarosite. Analyses of orbital data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) shows that the martian spectral equivalents are also consistent with mixtures of Al-phyllosilicates and jarosite, where the Al-phyllosilicate may also include kaolinite and/or halloysite. A case study for a region within Ius Chasma demonstrates that the relative proportions of the Al-phyllosilicate(s) and jarosite vary within one stratigraphic unit as well as between stratigraphic units. The former observation suggests that the jarosite may be a diagenetic (authigenic) product and thus indicative of local pH and redox conditions, whereas the latter observation may be consistent with variations in sediment flux and/or fluid chemistry during sediment deposition.

  14. Amino acid analogs IV:4-fluoroisoleucine.

    Science.gov (United States)

    Gershon, H; Shanks, L; Clarke, D D

    1978-05-01

    4-Fluoroisoleucine was produced by ammonolysis of 2-bromo-4-fluoro-3-methylpentanoic acid, which resulted from the bromofluorination of 4-methyl-2-pentenoic acid. It did not inhibit Plasmodium berghei in mice at 640 mg/kg and was not toxic to the animals. The fluoroamino acid inhibited Aspergillus niger, Trichoderma viride, Myrothecium verrucaria, Trichophyton mentagrophytes, and Mucor mucedo in Czapek solution agar at a concentration between 10(4) and 10(3) microgram/ml. Growth of Escherichia coli was inhibited 25% at 900 microgram/ml in a defined medium.

  15. Analogies: Explanatory Tools in Web-Based Science Instruction

    Science.gov (United States)

    Glynn, Shawn M.; Taasoobshirazi, Gita; Fowler, Shawn

    2007-01-01

    This article helps designers of Web-based science instruction construct analogies that are as effective as those used in classrooms by exemplary science teachers. First, the authors explain what analogies are, how analogies foster learning, and what form analogies should take. Second, they discuss science teachers' use of analogies. Third, they…

  16. EPOXYEICOSATRIENOIC ACID ANALOG ATTENUATES ANGIOTENSIN II HYPERTENSION AND KIDNEY INJURY

    Directory of Open Access Journals (Sweden)

    Md. Abdul Hye Khan

    2014-09-01

    Full Text Available Epoxyeicosatrienoic acids (EETs contribute to blood pressure regulation leading to the concept that EETs can be therapeutically targeted for hypertension and the associated end-organ damage. In the present study, we investigated anti-hypertensive and kidney protective actions of an EET analog, EET-B in angiotensin II (ANG II-induced hypertension. EET-B was administered in drinking water for 14 days (10mg/kg/d and resulted in a decreased blood pressure elevation in ANG II hypertension. At the end of the two-week period, blood pressure was 30 mmHg lower in EET analog-treated ANG II hypertensive rats. The vasodilation of mesenteric resistance arteries to acetylcholine was impaired in ANG II hypertension; however, it was improved with EET-B treatment. Further, EET-B protected the kidney in ANG II hypertension as evidenced by a marked 90% decrease in albuminuria and 54% decrease in nephrinuria. Kidney histology demonstrated a decrease in renal tubular cast formation in EET analog-treated hypertensive rats. In ANG II hypertension, EET-B treatment markedly lowered renal inflammation. Urinary monocyte chemoattractant protein-1 excretion was decreased by 55% and kidney macrophage infiltration was reduced by 52% with EET-B treatment. Overall, our results demonstrate that EET-B has anti-hypertensive properties, improves vascular function, and decreases renal inflammation and injury in ANG II hypertension.

  17. Epoxyeicosatrienoic acid analog attenuates angiotensin II hypertension and kidney injury.

    Science.gov (United States)

    Khan, Abdul Hye; Falck, John R; Manthati, Vijaya L; Campbell, William B; Imig, John D

    2014-01-01

    Epoxyeicosatrienoic acids (EETs) contribute to blood pressure regulation leading to the concept that EETs can be therapeutically targeted for hypertension and the associated end organ damage. In the present study, we investigated anti-hypertensive and kidney protective actions of an EET analog, EET-B in angiotensin II (ANG II)-induced hypertension. EET-B was administered in drinking water for 14 days (10 mg/kg/d) and resulted in a decreased blood pressure elevation in ANG II hypertension. At the end of the two-week period, blood pressure was 30 mmHg lower in EET analog-treated ANG II hypertensive rats. The vasodilation of mesenteric resistance arteries to acetylcholine was impaired in ANG II hypertension; however, it was improved with EET-B treatment. Further, EET-B protected the kidney in ANG II hypertension as evidenced by a marked 90% decrease in albuminuria and 54% decrease in nephrinuria. Kidney histology demonstrated a decrease in renal tubular cast formation in EET analog-treated hypertensive rats. In ANG II hypertension, EET-B treatment markedly lowered renal inflammation. Urinary monocyte chemoattractant protein-1 excretion was decreased by 55% and kidney macrophage infiltration was reduced by 52% with EET-B treatment. Overall, our results demonstrate that EET-B has anti-hypertensive properties, improves vascular function, and decreases renal inflammation and injury in ANG II hypertension.

  18. The First Synthesis and Anti-retroviral Activity of 5',5'-Difluoro-3'-Hydroxy-Apiosyl Nucleoside Cyclomonophosphonic Acid Analogs

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seyeon; Hong, Joon Hee [Chosun University, Gwangju (Korea, Republic of)

    2016-04-15

    The first synthesis of novel 5',5'-difluoro-30-hydroxy apiose nucleoside cyclomonophosphonic acid analogs was performed as potent anti-retroviral agents. Phosphonation was performed by direct displacement of a triflate intermediate with diethyl(lithiodifluoromethyl) phosphonate to give the corresponding(α, α-difluoroalkyl) phosphonate. Condensation successfully proceeded from a glycosyl donor with persilylated bases to yield the nucleoside phosphonate analogs. Deprotection of diethyl phosphonates provided the target nucleoside cyclomonophosphonic acid analogs. The synthesized nucleoside analogs were subjected to anti-viral screening against the human immunodeficiency virus-1 (HIV-1). Cytosine analogs show significant anti-HIV activity.

  19. Design and Functional Characterization of a Novel Abscisic Acid Analog.

    Science.gov (United States)

    Han, Xiaoqiang; Jiang, Lun; Che, Chuanliang; Wan, Chuan; Lu, Huizhe; Xiao, Yumei; Xu, Yanjun; Chen, Zhongzhou; Qin, Zhaohai

    2017-03-08

    The phytohormone abscisic acid (ABA) plays a crucial role in mediating plant growth and development by recruiting genetically redundant ABA receptors. To overcome its oxidation inactivation, we developed a novel ABA analog named 2',3'-benzo-iso-ABA (iso-PhABA) and studied its function and structural characterization with A. thaliana ABA receptors. The (+)-iso-PhABA form showed much higher ABA-like activities than (+)-ABA including inhibitory effects on the seed germination of lettuce and A. thaliana, wheat embryo germination and rice seedling elongation. The PP2C (protein phosphatases 2C) activity assay showed that (+)-iso-PhABA acted as a potent and selective ABA receptor agonist, which is preferred to PYL10. In some cases, (-)-iso-PhABA showed moderate to high activity for the PYL protein inhibiting PP2C activity, suggesting different mechanisms of action of iso-PhABA and ABA. The complex crystal structure of iso-PhABA with PYL10 was determined and elucidated successfully, revealing that (+)-iso-PhABA was better coordinated in the same binding pocket compared to (+)-ABA. Moreover, the detailed interaction network of iso-PhABA/PYL10 was disclosed and involves hydrogen bonds and multiple hydrophobic interactions that provide a robust framework for the design of novel ABA receptor agonists/antagonists.

  20. High affinity retinoic acid receptor antagonists: analogs of AGN 193109.

    Science.gov (United States)

    Johnson, A T; Wang, L; Gillett, S J; Chandraratna, R A

    1999-02-22

    A series of high affinity retinoic acid receptor (RAR) antagonists were prepared based upon the known antagonist AGN 193109 (2). Introduction of various phenyl groups revealed a preference for substitution at the para-position relative to the meta-site. Antagonists with the highest affinities for the RARs possessed hydrophobic groups, however, the presence of polar functionality was also well tolerated.

  1. Α-amino-β-fluorocyclopropanecarboxylic acids as a new tool for drug development: synthesis of glutamic acid analogs and agonist activity towards metabotropic glutamate receptor 4.

    Science.gov (United States)

    Lemonnier, Gérald; Lion, Cédric; Quirion, Jean-Charles; Pin, Jean-Philippe; Goudet, Cyril; Jubault, Philippe

    2012-08-01

    Herein we describe the diastereoselective synthesis of glutamic acid analogs and the evaluation of their agonist activity towards metabotropic glutamate receptor subtype 4 (mGluR4). These analogs are based on a monofluorinated cyclopropane core substituted with an α-aminoacid function. The potential of this new building block as a tool for the development of a novel class of drugs is demonstrated with racemic analog 11a that displayed the best agonist activity with an EC50 of 340 nM.

  2. Separative determination of ascorbic acid analogs contained in mushrooms by high-performance liquid chromatography.

    Science.gov (United States)

    Okamura, M

    1998-02-01

    Analogs (6-deoxyascorbic acid, erythroascorbic acid, and associated glycosides) of L-ascorbic acid (AA) contained in mushrooms were allowed to react with hydrazine to form osazones, and the conditions for separative determination by HPLC using a Zorbax SIL column were examined. Separation was started using solvent system 1 (ethylacetate/n-hexane/acetone/acetic acid, 50:50:1:1, v/v) as the mobile phase, and switching after 15 min to solvent system 2 (ethylacetate/acetone/acetic acid, 100:1:1, v/v). Detection was performed by absorbance at 500 nm. Because these analogs showed different formation rates for osazone, calibration curves were prepared for each substance. The recovery rate in the load test was 93-105%. By this method, AA and the analogs contained in eight species of edible mushrooms have been determined. The results revealed that: (1) the main constituents of all mushrooms are AA analogs rather than AA itself; (2) only one species contained AA in a very small amount (2 mumol/kg); (3) the types of AA analogs present differed according to the species of mushrooms, and (4) the total amount of AA analogs was between ca. 100-500 mumol/kg (2-9 mg per 100 g, converted to AA). In addition, a new AA analog was found in Pleurotus ostreatus and identified as 5-O-(alpha-D-xylopyranosyl)-D-erythroascorbic acid in structural analyses by NMR and other methods.

  3. Chromium analogs of iron-based superconductors

    Science.gov (United States)

    Edelmann, Martin; Sangiovanni, Giorgio; Capone, Massimo; de'Medici, Luca

    2017-05-01

    We theoretically investigate the d4 (Cr2 +) compound BaCr2As2 and show that, despite non-negligible differences in the electronic structure, its many-body physics mirrors that of BaFe2As2 , which has instead a d6 (Fe2 +) configuration. This reflects a symmetry of the electron correlation effects around the half-filled d5 Mott insulating state. Dynamical mean-field calculations correctly reproduce the experimental antiferromagnetic phase and, for realistic values of the interactions, they show a moderate mass enhancement of order ˜2 . This value can be insensitive to, or even be lowered by, an increase of the interaction parameters, as a result of a larger magnetic moment. In the paramagnetic phase however, correlation effects are much stronger, and the influence of the half-filled Mott insulator shows up as a crossover from a weakly correlated to an orbitally differentiated "Hund's metal" phase. This mirrors an analogous phenomenon in d6 iron compounds including a strong enhancement of the compressibility in a zone just inside the frontier between the normal and the Hund's metal. The experimental evidence and our theoretical description place BaCr2As2 at interaction strength slightly below the crossover which implies that negative pressures and/or electron doping (e.g., Cr → Mn, Fe or Ba → Sc, Y, La) might strongly enhance the compressibility, thereby possibly inducing high-Tc superconductivity in this nonsuperconducting compound.

  4. A new naphthalenepropanoic acid analog from the marine-derived actinomycetes Micromonospora sp. HS-HM-036.

    Science.gov (United States)

    Gao, Mei-Yue; Qi, Huan; Li, Jian-Song; Zhang, Hui; Zhang, Ji; Wang, Ji-Dong; Xiang, Wen-Sheng

    2017-09-01

    A new naphthalenepropanoic acid analog (1) was isolated from the broth of the actinomycetes Micromonospora sp. HS-HM-036. The structure of compound 1 was determined based on MS and extensive NMR analysis. A preliminary investigation of the biological activity of compound 1 was also described.

  5. Laboratory Hydrothermal Alteration of Basaltic Tephra by Acid Sulfate Solutions: An Analog Process for Martian Weathering

    Science.gov (United States)

    Golden, D. C.; Ming, D. W.; Morris, R. V.

    2003-01-01

    The objective of this study is to conduct simulated Mars-like weathering experiments in the laboratory to determine the weathering products that might form during oxidative, acidic weathering of Mars analog materials.

  6. A gravito-electromagnetic analogy based on tidal tensors

    CERN Document Server

    Costa, L F; Herdeiro, Carlos A. R.

    2006-01-01

    We propose a new approach to a physical analogy between General Relativity and Electromagnetism, based on comparing tidal tensors of both theories. Using this approach we write a covariant form for the gravitational analogues of the Maxwell equations, from which the regime of validity of the analogy becomes manifest. Two explicit realisations of the analogy are given. The first one matches linearised gravitational tidal tensors to exact electromagnetic tidal tensors in Minkwoski spacetime. The second one matches exact magnetic gravitational tidal tensors for ultra-stationary metrics to exact magnetic tidal tensors of electromagnetism in curved spaces. We then establish a new proof for a class of tensor identities that define invariants of the type $\\vec{E}^2-\\vec{B}^2$ and $\\vec{E}\\cdot\\vec{B}$, and we exhibit the invariants built from tidal tensors in both gravity and electromagnetism. We contrast our approach with the two gravito-electromagnetic analogies commonly found in the literature, which are reviewed...

  7. Structure-activity relationship studies on natural and synthetic bile acid analogs.

    Science.gov (United States)

    Roda, A; Grigolo, B; Pellicciari, R; Natalini, B

    1989-12-01

    The objective of our research was to develop ursodiol analogs that are structurally modified to modulate hepatic side-chain amidation and prevent 7-dehydroxylation by intestinal bacteria while at the same time maintaining the critical micellar concentration (CMC) and hydrophilicity of ursodiol. More than 20 naturally occurring bile acids were screened for physicochemical properties. Then, two generations of analogs were studied, and those with physicochemical properties similar to ursodiol's were analyzed for physiologic properties. The first generation of analogs included molecules with steric and/or electronic hindrance on the side chain; the second group consisted of the same molecules conjugated with glycine or taurine and also "pseudoconjugated" analogs (23-hydroxylated, esterified, and amidated with other amino acids). Of the first-generation analogs, only cyclopropane D derivative and trans-olefin were useful to our purposes, being conjugated by the liver and almost completely recovered in bile. These two analogs were deconjugated and 7-dehydroxylated but with slower kinetics. The hydrophilicity of the molecules could be augmented by increasing the polarity of the steroid ring. Among the pseudoconjugated analogs, the CMC values were similar to those of the natural analogs, although hydrophobicity differed among the group. The analogs that were not deconjugated were not 7-dehydroxylated either. All of the pseudoconjugated bile acids were efficiently taken up by the liver, and their recovery in bile was similar to that of glycine and taurine ursodiol. From these studies we now know that side chain configuration and conformation are important in the conjugation and deconjugation processes. Mild modification of the side chain can prevent 7-dehydroxylation and thus yield a bile acid more resistant to intestinal bacteria and more bioavailable. Prevention of hepatic conjugation improves biliary secretion and recovery of many analogs.

  8. An Optimized Analogy-Based Project Effort Estimation

    Directory of Open Access Journals (Sweden)

    Mohammad Azzeh

    2014-05-01

    Full Text Available despite the predictive performance of Analogy-Based Estimation (ABE in generating better effort estimates, there is no consensus on: (1 how to predetermine the appropriate number of analogies, (2 which adjustment technique produces better estimates. Yet, there is no prior works attempted to optimize both number of analogies and feature distance weights for each test project. Perhaps rather than using fixed number, it is better to optimize this value for each project individually and then adjust the retrieved analogies by optimizing and approximating complex relationships between features and reflects that approximation on the final estimate. The Artificial Bees Algorithm is utilized to find, for each test project, the appropriate number of closest projects and features distance weights that is used to adjust those analogies’ efforts. The proposed technique has been applied and validated to 8 publically datasets from PROMISE repository. Results obtained show that: (1 the predictive performance of ABE has noticeably been improved, (2 the number of analogies was remarkably variable for each test project. While there are many techniques to adjust ABE, Using optimization algorithm provides two solutions in one technique and appeared useful for datasets with complex structure.

  9. Analog Group Delay Equalizers Design Based on Evolutionary Algorithm

    Directory of Open Access Journals (Sweden)

    M. Laipert

    2006-04-01

    Full Text Available This paper deals with a design method of the analog all-pass filter designated for equalization of the group delay frequency response of the analog filter. This method is based on usage of evolutionary algorithm, the Differential Evolution algorithm in particular. We are able to design such equalizers to be obtained equal-ripple group delay frequency response in the pass-band of the low-pass filter. The procedure works automatically without an input estimation. The method is presented on solving practical examples.

  10. Asymmetric synthesis of -aminophosphonates: The bio-isosteric analogs of -aminobutyric acid

    Indian Academy of Sciences (India)

    Kalisankar Bera; Dwayaja Nadkarni; Iirishi N N Namboothiri

    2013-05-01

    The properties of aminophosphonates as transition state analogs of amino acids, and as antibacterial, antifungal and antiHIV agents attracted considerable attention in recent years. Although many reviews appeared in the literature covering - and -aminophosphonates, -aminophosphonates did not receive sufficient attention despite the fact that parent -aminophosphonic acid and its derivatives are bio-isosteric analogs of GABA (-amino butyric acid). This review provides a critical summary of the significance of -aminophosphonates and various approaches to their synthesis, with particular emphasis to asymmetric versions.

  11. Analog Circuit Design Optimization Based on Evolutionary Algorithms

    Directory of Open Access Journals (Sweden)

    Mansour Barari

    2014-01-01

    Full Text Available This paper investigates an evolutionary-based designing system for automated sizing of analog integrated circuits (ICs. Two evolutionary algorithms, genetic algorithm and PSO (Parswal particle swarm optimization algorithm, are proposed to design analog ICs with practical user-defined specifications. On the basis of the combination of HSPICE and MATLAB, the system links circuit performances, evaluated through specific electrical simulation, to the optimization system in the MATLAB environment, for the selected topology. The system has been tested by typical and hard-to-design cases, such as complex analog blocks with stringent design requirements. The results show that the design specifications are closely met. Comparisons with available methods like genetic algorithms show that the proposed algorithm offers important advantages in terms of optimization quality and robustness. Moreover, the algorithm is shown to be efficient.

  12. GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

    Science.gov (United States)

    Henck, Colin; Nally, Luke

    2007-01-01

    An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

  13. GC-MS Analysis of [gamma]-Hydroxybutyric Acid Analogs: A Forensic Chemistry Experiment

    Science.gov (United States)

    Henck, Colin; Nally, Luke

    2007-01-01

    An upper-division forensic chemistry experiment is described. It involves using glycolic acid and sodium glycolate as analogs of [gamma]-hydroxybutyric acid and its sodium salt. The experiment shows the use of silylation in GC-MS analysis and gives students the opportunity to work with a commonly used silylating reagent,…

  14. {alpha}-methylene and glycidic acid analogs of IPPA as potential myocardial imaging agents

    Energy Technology Data Exchange (ETDEWEB)

    Ruyan, M. K.; Bakan, D. A.; Skinner, R. W. S.; Newman, C.; Gross, M. D.; Counsell, R. E

    1995-01-01

    Using organozinc cross-coupling reactions, two radiolabeled analogs of 15-(p-iodophenyl) pentadecanoic acid (IPPA) have been designed and synthesized as potential scintigraphic imaging agents for the heart. Both 15-(4-iodophenyl)-tridecylglycidic acid and 15-(4-iodophenyl)-2-methylene pentadecanoic acid were synthesized and radioiodinated. In tissue biodistribution studies in rats, only the {alpha}-methylene derivative of IPPA displayed a consistently higher heart to blood ratio and a substantially lower degree of thyroid accumulation than did IPPA alone. With respect to a scintigraphic imaging efficacy, the {alpha}-methylene analog of IPPA and IPPA itself showed essentially equivalent cardiac imaging profiles in rabbits, with a slight extension in imaging time for the {alpha}-methylene analog of IPPA.

  15. Analogy between gambling and measurement-based work extraction

    Science.gov (United States)

    Vinkler, Dror A.; Permuter, Haim H.; Merhav, Neri

    2016-04-01

    In information theory, one area of interest is gambling, where mutual information characterizes the maximal gain in wealth growth rate due to knowledge of side information; the betting strategy that achieves this maximum is named the Kelly strategy. In the field of physics, it was recently shown that mutual information can characterize the maximal amount of work that can be extracted from a single heat bath using measurement-based control protocols, i.e. using ‘information engines’. However, to the best of our knowledge, no relation between gambling and information engines has been presented before. In this paper, we briefly review the two concepts and then demonstrate an analogy between gambling, where bits are converted into wealth, and information engines, where bits representing measurements are converted into energy. From this analogy follows an extension of gambling to the continuous-valued case, which is shown to be useful for investments in currency exchange rates or in the stock market using options. Moreover, the analogy enables us to use well-known methods and results from one field to solve problems in the other. We present three such cases: maximum work extraction when the probability distributions governing the system and measurements are unknown, work extraction when some energy is lost in each cycle, e.g. due to friction, and an analysis of systems with memory. In all three cases, the analogy enables us to use known results in order to obtain new ones.

  16. Improvements of Analog Neural Networks Based on Kalman Filter

    Directory of Open Access Journals (Sweden)

    Z. Raida

    2002-04-01

    Full Text Available In the paper, original improvements of recurrent analog neuralnetworks, which are based on Kalman filter, are presented. Theseimprovements eliminate some disadvantages of the classical Kalmanneural network and enable a real time processing of quickly changingsignals, which appear in adaptive antennas and similar applications.This goal is reached using such circuit elements, which increase theconvergence rate of the network and decrease the dependence ofconvergence rate on the ratio of eigenvalues of the correlation matrixof input signals.

  17. Gray Code ADC Based on an Analog Neural Circuit

    Directory of Open Access Journals (Sweden)

    L. Michaeli

    1995-04-01

    Full Text Available In this paper a new neural ADC design is presented, which is based on the idea to replace all functional components needed in the ADC block scheme by a simple connection of neurons. Transformation of ADC functional scheme into an analog neural structure and its computer simulation is one of the main results of this paper. Furthermore, a discrete component prototype of the proposed A/D converter is discussed and experimental results are also given.

  18. Uptake of triiodothyronine and triiodothyroacetic acid in neonatal rat cardiomyocytes: effects of metabolites and analogs

    NARCIS (Netherlands)

    F.A. Verhoeven; H.H. van der Putten; G. Hennemann; J.M.J. Lamers (Jos); T.J. Visser (Theo); M.E. Everts (Maria)

    2002-01-01

    textabstractCellular and nuclear uptake of [125I]tri-iodothyronine (T3) and [125I]triiodothyroacetic acid (Triac) were compared in cardiomyocytes of 2-3 day old rats, and the effect of thyroid hormone analogs on cellular T(3) uptake was measured. Cells (5-10 x 10(5) per well) were

  19. Calculation of the free energy of solvation for neutral analogs of amino acid side chains

    NARCIS (Netherlands)

    Villa, Alessandra; Mark, AE

    2002-01-01

    The ability of the GROMOS96 force field to reproduce partition constants between water and two less polar solvents (cyclohexane and chloroform) for analogs of 18 of the 20 naturally occurring amino acids has been investigated. The estimations of the solvation free energies in water, in cyclohexane

  20. Wavelet neural network based fault diagnosis in nonlinear analog circuits

    Institute of Scientific and Technical Information of China (English)

    Yin Shirong; Chen Guangju; Xie Yongle

    2006-01-01

    The theories of diagnosing nonlinear analog circuits by means of the transient response testing are studied. Wavelet analysis is made to extract the transient response signature of nonlinear circuits and compress the signature dada. The best wavelet function is selected based on the between-category total scatter of signature. The fault dictionary of nonlinear circuits is constructed based on improved back-propagation(BP) neural network. Experimental results demonstrate that the method proposed has high diagnostic sensitivity and fast fault identification and deducibility.

  1. Ordered cleavage of myeloperoxidase ester bonds releases active site heme leading to inactivation of myeloperoxidase by benzoic acid hydrazide analogs.

    Science.gov (United States)

    Huang, Jiansheng; Smith, Forrest; Panizzi, Peter

    2014-04-15

    Myeloperoxidase (MPO) catalyzes the breakdown of hydrogen peroxide and the formation of the potent oxidant hypochlorous acid. We present the application of the fluorogenic peroxidase substrate 10-acetyl-3,7-dihydroxyphenoxazine (ADHP) in steady-state and transient kinetic studies of MPO function. Using initial kinetic parameters for the MPO system, we characterized under the same conditions a number of gold standards for MPO inhibition, namely 4-amino benzoic acid hydrazide (4-ABAH), isoniazid and NaN3 before expanding our focus to isomers of 4-ABAH and benzoic acid hydrazide analogs. We determined that in the presence of hydrogen peroxide that 4-ABAH and its isomer 2-ABAH are both slow-tight binding inhibitors of MPO requiring at least two steps, whereas NaN3 and isoniazid-based inhibition has a single observable step. We also determined that MPO inhibition by benzoic acid hydrazide and 4-(trifluoromethyl) benzoic acid hydrazide was due to hydrolysis of the ester bond between MPO heavy chain Glu 242 residue and the heme pyrrole A ring, freeing the light chain and heme b fragment from the larger remaining MPO heavy chain. This new mechanism would essentially indicate that the benzoic acid hydrazide analogs impart inhibition through initial ejection of the heme catalytic moiety without prior loss of the active site iron.

  2. An expanded set of amino acid analogs for the ribosomal translation of unnatural peptides.

    Directory of Open Access Journals (Sweden)

    Matthew C T Hartman

    Full Text Available BACKGROUND: The application of in vitro translation to the synthesis of unnatural peptides may allow the production of extremely large libraries of highly modified peptides, which are a potential source of lead compounds in the search for new pharmaceutical agents. The specificity of the translation apparatus, however, limits the diversity of unnatural amino acids that can be incorporated into peptides by ribosomal translation. We have previously shown that over 90 unnatural amino acids can be enzymatically loaded onto tRNA. METHODOLOGY/PRINCIPAL FINDINGS: We have now used a competition assay to assess the efficiency of tRNA-aminoacylation of these analogs. We have also used a series of peptide translation assays to measure the efficiency with which these analogs are incorporated into peptides. The translation apparatus tolerates most side chain derivatives, a few alpha,alpha disubstituted, N-methyl and alpha-hydroxy derivatives, but no beta-amino acids. We show that over 50 unnatural amino acids can be incorporated into peptides by ribosomal translation. Using a set of analogs that are efficiently charged and translated we were able to prepare individual peptides containing up to 13 different unnatural amino acids. CONCLUSIONS/SIGNIFICANCE: Our results demonstrate that a diverse array of unnatural building blocks can be translationally incorporated into peptides. These building blocks provide new opportunities for in vitro selections with highly modified drug-like peptides.

  3. Hamiltonian system for orthotropic plate bending based on analogy theory

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Based on analogy between plane elasticity and plate bending as well as variational principles of mixed energy, Hamiltonian system is further led to orthotropic plate bending problems in this paper. Thus many effective methods of mathematical physics such as separation of variables and eigenfunction expansion can be employed in orthotropic plate bending problems as they are used in plane elasticity. Analytical solutions of rectangular plate are presented directly, which expands the range of analytical solutions. There is an essential distinction between this method and traditional semi-inverse method. Numerical results of orthotropic plate with two lateral sides fixed are included to demonstrate the effectiveness and accuracy of this method.

  4. Lunar Analog

    Science.gov (United States)

    Cromwell, Ronita L.

    2009-01-01

    In this viewgraph presentation, a ground-based lunar analog is developed for the return of manned space flight to the Moon. The contents include: 1) Digital Astronaut; 2) Bed Design; 3) Lunar Analog Feasibility Study; 4) Preliminary Data; 5) Pre-pilot Study; 6) Selection of Stockings; 7) Lunar Analog Pilot Study; 8) Bed Design for Lunar Analog Pilot.

  5. A synthetic uric acid analog accelerates cutaneous wound healing in mice.

    Directory of Open Access Journals (Sweden)

    Srinivasulu Chigurupati

    Full Text Available Wound healing is a complex process involving intrinsic dermal and epidermal cells, and infiltrating macrophages and leukocytes. Excessive oxidative stress and associated inflammatory processes can impair wound healing, and antioxidants have been reported to improve wound healing in animal models and human subjects. Uric acid (UA is an efficient free radical scavenger, but has a very low solubility and poor tissue penetrability. We recently developed novel UA analogs with increased solubility and excellent free radical-scavenging properties and demonstrated their ability to protect neural cells against oxidative damage. Here we show that the uric acid analog (6, 8 dithio-UA, but not equimolar concentrations of UA or 1, 7 dimethyl-UA modified the behaviors of cultured vascular endothelial cells, keratinocytes and fibroblasts in ways consistent with enhancement of the wound healing functions of all three cell types. We further show that 6, 8 dithio-UA significantly accelerates the wound healing process when applied topically (once daily to full-thickness wounds in mice. Levels of Cu/Zn superoxide dismutase were increased in wound tissue from mice treated with 6, 8 dithio-UA compared to vehicle-treated mice, suggesting that the UA analog enhances endogenous cellular antioxidant defenses. These results support an adverse role for oxidative stress in wound healing and tissue repair, and provide a rationale for the development of UA analogs in the treatment of wounds and for modulation of angiogenesis in other pathological conditions.

  6. Analog Optical Computing Based on Dielectric Meta-reflect-array

    CERN Document Server

    Chizari, Ata; Jamali, Mohammad Vahid; Salehi, Jawad A

    2016-01-01

    In this paper, we realize the concept of analog computing using an array of engineered gradient dielectric meta-reflect-array. The proposed configuration consists of individual subwavelength silicon nanobricks in combination with fused silica spacer and silver ground plane realizing a reflection beam with full phase coverage $2\\pi$ degrees as well as amplitude range $0$ to $1$. Spectrally overlapping electric and magnetic dipole resonances, such high-index dielectric metasurfaces can locally and independently manipulate the amplitude and phase of the incident electromagnetic wave. This practically feasible structure overcomes substantial limitations imposed by plasmonic metasurfaces such as absorption losses and low polarization conversion efficiency in the visible range. Using such CMOS-compatible and easily integrable platforms promises highly efficient ultrathin planar wave-based computing systems which circumvent the drawbacks of conventional bulky lens-based signal processors. Based on these key properti...

  7. Investigations and design of pyridine-2-carboxylic acid thiazol-2-ylamide analogs as methionine aminopeptidase inhibitors using 3D-QSAR and molecular docking

    DEFF Research Database (Denmark)

    Hauser, Alexander Sebastian

    2014-01-01

    -dimensional quantitative structure–activity relationship (3D-QSAR) studies were carried out on a series of pyridine-2-carboxylic acid thiazol-2-ylamide-based MetAP inhibitors using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) techniques. The models were...... complexes, four new pyridine-2-carboxylic acid thiazol-2-ylamide analogs were designed. These analogs exhibit significantly better predicted activity than the reported molecules. The present work has implications for the development of novel antibiotics as potent MetAP inhibitors....

  8. The epoxyeicosatrienoic acid analog PVPA ameliorates cyclosporine-induced hypertension and renal injury in rats.

    Science.gov (United States)

    Yeboah, Michael M; Hye Khan, Md Abdul; Chesnik, Marla A; Sharma, Amit; Paudyal, Mahesh P; Falck, John R; Imig, John D

    2016-09-01

    The introduction of calcineurin inhibitors (CNI) into clinical practice in the late 1970s transformed organ transplantation and led to significant improvement in acute rejection episodes. However, despite their significant clinical utility, the use of these agents is hampered by the development of hypertension and nephrotoxicity, which ultimately lead to end-stage kidney disease and overt cardiovascular outcomes. There are currently no effective agents to treat or prevent these complications. Importantly, CNI-free immunosuppressive regimens lack the overall efficacy of CNI-based treatments and put patients at risk of allograft rejection. Cytochrome P-450 epoxygenase metabolites of arachidonic acid, epoxyeicosatrienoic acids (EETs), have potent vasodilator and antihypertensive properties in addition to many cytoprotective effects, but their effects on CNI-induced nephrotoxicity have not been explored. Here, we show that PVPA, a novel, orally active analog of 14,15-EET, effectively prevents the development of hypertension and ameliorates kidney injury in cyclosporine-treated rats. PVPA treatment reduced proteinuria and renal dysfunction induced by cyclosporine. PVPA inhibited inflammatory cell infiltration into the kidney and decreased renal fibrosis. PVPA also reduced tubular epithelial cell apoptosis, attenuated the generation of reactive oxygen species, and modulated the unfolded protein response that is associated with endoplasmic reticulum stress. Consistent with the in vivo data, PVPA attenuated cyclosporine-induced apoptosis of NRK-52E cells in vitro. These data indicate that the cytochrome P-450/EET system offers a novel therapeutic strategy to treat or prevent CNI-induced nephrotoxicity. Copyright © 2016 the American Physiological Society.

  9. Characterization of an organic acid analog model in Adirondack, New York, surface waters

    Science.gov (United States)

    Fakhraei, H.; Driscoll, C. T.

    2013-12-01

    Natural waters include a variety of organic matter that differs in composition and functional groups. Dissolved organic matter is important but difficult to characterize acidic and metal binding (e.g., Al) functional groups in chemical equilibrium models. In this study data from Adirondack Lake Survey were used to calibrate an organic acid analog model in order to quantify the influence of organic acids on surface water chemistry. The study sites in the Adirondack region of New York have diverse levels of dissolved organic carbon (DOC), used as a surrogate for organic acids. DOC in 55 Adirondack surface waters varies from 180 μmol C/l (in Little Echo Pond) to 1263 μmol C/l (in Sunday Pond). To reduce the variability inherited in the large raw data set, suite of mean observations was constructed by grouping and averaging measured data into pH intervals of 0.05 pH units from pH 4.15 to 7.3. A chemical equilibrium model, which includes major solutes in natural waters, was linked to an optimization algorithm (genetic algorithm) to calibrate a triprotic organic analog model which includes proton and aluminum binding by adjusting the dissociation constants and site density of DOC. The object of fitting procedure was to simultaneously minimize the discrepancy between observed and simulated pH, acid neutralizing capacity (ANC), organic monomeric aluminum and inorganic monomeric aluminum. A sensitivity analysis on calibrated values indicate that the speciation of the modeled solutes are most responsive to the dissociation constant of AlOrg= Al3+ + Org3- reaction (Org3- represents organic anion), the site density of DOC and the second H+ dissociation constant of the triprotic organic analog (i.e. H2Org- = 2H+ + Org3- reaction).

  10. Photonic digital-to-analog conversion based on wavelength multiplexing

    Science.gov (United States)

    Yang, Shuna; Hu, Miao; Chi, Hao; Li, Qiliang

    2017-10-01

    A novel photonic digital-to-analog conversion (PDAC) scheme, which is based on optical intensity weighting and multiplexing/summing of different wavelengths, is proposed. The employment of wavelength multiplexing in the system, which conducts the function of modulated light intensity summation, greatly simplifies the system complexity and improves the conversion speed/accuracy limited by large-area photo-detectors and associated electronics. A 4-bit PDAC with a conversion speed of 10 GS/s demonstrates the feasibility of the proposed scheme. In addition, the performance degradation induced by the limited extinction ratios of the applied electro-optic modulators, the synchronization errors among different wavelength channels, and the bit resolutions of the built system is also discussed.

  11. Acid-Base Homeostasis.

    Science.gov (United States)

    Hamm, L Lee; Nakhoul, Nazih; Hering-Smith, Kathleen S

    2015-12-07

    Acid-base homeostasis and pH regulation are critical for both normal physiology and cell metabolism and function. The importance of this regulation is evidenced by a variety of physiologic derangements that occur when plasma pH is either high or low. The kidneys have the predominant role in regulating the systemic bicarbonate concentration and hence, the metabolic component of acid-base balance. This function of the kidneys has two components: reabsorption of virtually all of the filtered HCO3(-) and production of new bicarbonate to replace that consumed by normal or pathologic acids. This production or generation of new HCO3(-) is done by net acid excretion. Under normal conditions, approximately one-third to one-half of net acid excretion by the kidneys is in the form of titratable acid. The other one-half to two-thirds is the excretion of ammonium. The capacity to excrete ammonium under conditions of acid loads is quantitatively much greater than the capacity to increase titratable acid. Multiple, often redundant pathways and processes exist to regulate these renal functions. Derangements in acid-base homeostasis, however, are common in clinical medicine and can often be related to the systems involved in acid-base transport in the kidneys.

  12. An amino acid depleted cell-free protein synthesis system for the incorporation of non-canonical amino acid analogs into proteins.

    Science.gov (United States)

    Singh-Blom, Amrita; Hughes, Randall A; Ellington, Andrew D

    2014-05-20

    Residue-specific incorporation of non-canonical amino acids into proteins is usually performed in vivo using amino acid auxotrophic strains and replacing the natural amino acid with an unnatural amino acid analog. Herein, we present an efficient amino acid depleted cell-free protein synthesis system that can be used to study residue-specific replacement of a natural amino acid by an unnatural amino acid analog. This system combines a simple methodology and high protein expression titers with a high-efficiency analog substitution into a target protein. To demonstrate the productivity and efficacy of a cell-free synthesis system for residue-specific incorporation of unnatural amino acids in vitro, we use this system to show that 5-fluorotryptophan and 6-fluorotryptophan substituted streptavidin retain the ability to bind biotin despite protein-wide replacement of a natural amino acid for the amino acid analog. We envisage this amino acid depleted cell-free synthesis system being an economical and convenient format for the high-throughput screening of a myriad of amino acid analogs with a variety of protein targets for the study and functional characterization of proteins substituted with unnatural amino acids when compared to the currently employed in vivo methodologies.

  13. Visualizing Uncertainty for Probabilistic Weather Forecasting based on Reforecast Analogs

    Science.gov (United States)

    Pelorosso, Leandro; Diehl, Alexandra; Matković, Krešimir; Delrieux, Claudio; Ruiz, Juan; Gröeller, M. Eduard; Bruckner, Stefan

    2016-04-01

    Numerical weather forecasts are prone to uncertainty coming from inaccuracies in the initial and boundary conditions and lack of precision in numerical models. Ensemble of forecasts partially addresses these problems by considering several runs of the numerical model. Each forecast is generated with different initial and boundary conditions and different model configurations [GR05]. The ensembles can be expressed as probabilistic forecasts, which have proven to be very effective in the decision-making processes [DE06]. The ensemble of forecasts represents only some of the possible future atmospheric states, usually underestimating the degree of uncertainty in the predictions [KAL03, PH06]. Hamill and Whitaker [HW06] introduced the "Reforecast Analog Regression" (RAR) technique to overcome the limitations of ensemble forecasting. This technique produces probabilistic predictions based on the analysis of historical forecasts and observations. Visual analytics provides tools for processing, visualizing, and exploring data to get new insights and discover hidden information patterns in an interactive exchange between the user and the application [KMS08]. In this work, we introduce Albero, a visual analytics solution for probabilistic weather forecasting based on the RAR technique. Albero targets at least two different type of users: "forecasters", who are meteorologists working in operational weather forecasting and "researchers", who work in the construction of numerical prediction models. Albero is an efficient tool for analyzing precipitation forecasts, allowing forecasters to make and communicate quick decisions. Our solution facilitates the analysis of a set of probabilistic forecasts, associated statistical data, observations and uncertainty. A dashboard with small-multiples of probabilistic forecasts allows the forecasters to analyze at a glance the distribution of probabilities as a function of time, space, and magnitude. It provides the user with a more

  14. Microwave-Assisted Radiosynthesis of [18F]Fluorinated Fatty Acid Analogs

    Science.gov (United States)

    Belanger, Anthony P.; Pandey, Mukesh K.; DeGrado, Timothy R.

    2010-01-01

    Microwave reactors remain largely underutilized in the field of PET chemistry. This is particularly unfortunate since microwave synthesis elegantly addresses two of the most critical issues of PET radiochemistry with short-lived radionuclides: reaction rate and side-product formation. In this study we investigate the efficiency of synthesis of terminally [18F]fluorinated fatty acid analogs using a commercial microwave reactor in comparison with conventional heating. Methods The labeling precursors were methyl esters of terminally substituted alkyl bromides and iodides. Duration and temperatures of the [18F]fluorination reaction were varied. Chemical and radiochemical purities, and radiochemical yields were investigated for conventional (CH) and microwave-assisted (MW) radiosyntheses. Results The results demonstrate that microwave heating enhanced [18F]fluoride incorporation to >95% (up to 55% improvement), while reducing reaction times to 2 min (~10-fold reduction) or temperatures to 55–60°C (20°C reduction). Overall decay-corrected radiochemical yields of purified [18F]fluoro fatty acids were higher (MW=49.0 ± 4.5%, CH=23.6 ± 3.5%, p<0.05) with microwave heating and side-products were notably fewer. Conclusion For routine synthesis of [18F]fluoro fatty acid analogs, microwave heating is faster, milder, cleaner, less variable and higher yielding than conventional heating and therefore the preferred reaction method. PMID:21492792

  15. New acid BisGMA analogs for dental adhesive applications with antimicrobial activity.

    Science.gov (United States)

    Melinte, Violeta; Buruiana, Tinca; Chibac, Andreea; Mares, Mihai; Aldea, Horia; Buruiana, Emil C

    2016-12-01

    To achieve bisphenol A glycerolate dimethacrylate (BisGMA) analogs with reduced viscosity to be used in the formulation of dental adhesives containing biocidal components. A series of low-viscosity BisGMA derivatives (η: 39-12Pas) modified with 30, 60 and, respectively 80mol% carboxylic acid units were synthesized and characterized. Hydrogen bonding interactions in our monomers, the photopolymerization behavior and implicitly the conversion degree (DC) for some experimental adhesive formulations containing acid-modified BisGMA, commercial BisGMA (only in F1-F3), triethyleneglycol dimethacrylate and 2-hydroxyethyl methacrylate were examined by FTIR spectroscopy. The water effects on the photocrosslinked networks together with the flexural strength/modulus were also investigated. The adhesive penetration into the dentin surface was surveyed by SEM analysis, and the antimicrobial activity triggered by the incorporation of 0.5wt% AgNO3, 10wt% zinc methacrylate or 1wt% triclosan methacrylate in selected adhesive formulations on the growth of Streptococcus mutans and Candida albicans strains was evidenced. The contribution of the hydrogen bonding interactions was found to be lower in BisGMA derivatives than in non-modified BisGMA, and the DC varied between 56.5 (F6) and 83.7% (F1) compared with a control formulation based on BisGMA:TEGDMA (DC=58.2%). The flexural strength and flexural modulus varied in the range 33.7MPa (F6)-54.4MPa (F8)MPa and 0.64 (F6)-1.43 (F8)GPa, respectively. SEM observation of adhesive-dentin interface revealed the formation of resin tags for the carboxyl-containing adhesive, while for the control adhesive they are hardly formed. Also, the microorganism development was inhibited, the proposed materials displaying antimicrobial activity. The experimental formulations based on carboxyl-functionalized BisGMA exhibit a similar or even improved behavior over control sample, suggesting their potential applicability as antimicrobial dental adhesives

  16. X-ray structure based evaluation of analogs of citalopram

    DEFF Research Database (Denmark)

    Topiol, Sid; Bang-Andersen, Benny; Sanchez, Connie

    2017-01-01

    analogs, showing distinct structure-activity relationship (SAR) at both sites that is independent of the SAR at the other site. Analogs with a higher affinity and selectivity than benchmark R-Citalopram (R-Cit) for the S2 versus the S1 site were identified. We deploy structural and computational analyses...... to explain this SAR and demonstrate the potential utility of the newly emerging X-ray structures within the neurotransmitter:sodium Symporter family for drug design....

  17. Grobner Bases for Nonlinear DAE Systems of Analog Circuits

    Directory of Open Access Journals (Sweden)

    Silke J. Spang

    2008-04-01

    Full Text Available Systems of differential equations play an important role in modelling and analysis of many complex systems e.g. in electronics and mechanics. The following article is concerned with a symbolic analysis approach for reduction of the differential index of nonlinear differential algebraic equation (DAE systems, which occur in the modelling and simulation of analog circuits.

  18. Secure Analog Data Transmission Based on Rössler Chaotic System Behavior

    OpenAIRE

    Daniel CURIAC; Ioan FILIP; Florin DRĂGAN

    2000-01-01

    This paper describes a new methodology for increasing the security of analog data transmission based on a mixture of the original analog signal with one of the state variables of Rössler chaotic system. The method is described emphasizing on the practical implementation aspects.

  19. Secure Analog Data Transmission Based on Rössler Chaotic System Behavior

    Directory of Open Access Journals (Sweden)

    Daniel CURIAC

    2000-12-01

    Full Text Available This paper describes a new methodology for increasing the security of analog data transmission based on a mixture of the original analog signal with one of the state variables of Rössler chaotic system. The method is described emphasizing on the practical implementation aspects.

  20. Profiling of hepatic gene expression in rats treated with fibric acid analogs

    Energy Technology Data Exchange (ETDEWEB)

    Cornwell, Paul D.; Souza, Angus T. de; Ulrich, Roger G

    2004-05-18

    Peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptors whose ligands include fatty acids, eicosanoids and the fibrate class of drugs. In humans, fibrates are used to treat dyslipidemias. In rodents, fibrates cause peroxisome proliferation, a change that might explain the observed hepatomegaly. In this study, rats were treated with multiple dose levels of six fibric acid analogs (including fenofibrate) for up to two weeks. Pathological analysis identified hepatocellular hypertrophy as the only sign of hepatotoxicity, and only one compound at the highest dose caused any significant increase in serum ALT or AST activity. RNA profiling revealed that the expression of 1288 genes was related to dose or length of treatment and correlated with hepatocellular hypertrophy. This gene list included expression changes that were consistent with increased mitochondrial and peroxisomal {beta}-oxidation, increased fatty acid transport, increased hepatic uptake of LDL-cholesterol, decreased hepatic uptake of glucose, decreased gluconeogenesis and decreased glycolysis. These changes are likely linked to many of the clinical benefits of fibrate drugs, including decreased serum triglycerides, decreased serum LDL-cholesterol and increased serum HDL-cholesterol. In light of the fact that all six compounds stimulated similar or identical changes in the expression of this set of 1288 genes, these results indicate that hepatomegaly is due to PPAR{alpha} activation, although signaling through other receptors (e.g. PPAR{gamma}, RXR) or through non-receptor pathways cannot be excluded.

  1. Synthesis and evaluation of indazole based analog sensitive Akt inhibitors.

    Science.gov (United States)

    Okuzumi, Tatsuya; Ducker, Gregory S; Zhang, Chao; Aizenstein, Brian; Hoffman, Randy; Shokat, Kevan M

    2010-08-01

    The kinase Akt is a key signaling node in regulating cellular growth and survival. It is implicated in cancer by mutation and its role in the downstream transmission of aberrant PI3K signaling. For these reasons, Akt has become an increasingly important target of drug development efforts and several inhibitors are now reaching clinical trials. Paradoxically it has been observed that active site kinase inhibitors of Akt lead to hyperphosphorylation of Akt itself. To investigate this phenomenon we here describe the application of a chemical genetics strategy that replaces native Akt with a mutant version containing an active site substitution that allows for the binding of an engineered inhibitor. This analog sensitive strategy allows for the selective inhibition of a single kinase. In order to create the inhibitor selective for the analog sensitive kinase, a diversity of synthetic approaches was required, finally resulting in the compound PrINZ, a 7-substituted version of the Abbott Labs Akt inhibitor A-443654.

  2. Inviting Argument by Analogy: Analogical-Mapping-Based Comparison Activities as a Scaffold for Small-Group Argumentation

    Science.gov (United States)

    Emig, Brandon R.; McDonald, Scott; Zembal-Saul, Carla; Strauss, Susan G.

    2014-01-01

    This study invited small groups to make several arguments by analogy about simple machines. Groups were first provided training on analogical (structure) mapping and were then invited to use analogical mapping as a scaffold to make arguments. In making these arguments, groups were asked to consider three simple machines: two machines that they had…

  3. Synthesis, structural characterization and effect on human granulocyte intracellular cAMP levels of abscisic acid analogs.

    Science.gov (United States)

    Bellotti, Marta; Salis, Annalisa; Grozio, Alessia; Damonte, Gianluca; Vigliarolo, Tiziana; Galatini, Andrea; Zocchi, Elena; Benatti, Umberto; Millo, Enrico

    2015-01-01

    The phytohormone abscisic acid (ABA), in addition to regulating physiological functions in plants, is also produced and released by several mammalian cell types, including human granulocytes, where it stimulates innate immune functions via an increase of the intracellular cAMP concentration ([cAMP]i). We synthesized several ABA analogs and evaluated the structure-activity relationship, by the systematical modification of selected regions of these analogs. The resulting molecules were tested for their ability to inhibit the ABA-induced increase of [cAMP]i in human granulocytes. The analogs with modified configurations at C-2' and C-3' abrogated the ABA-induced increase of the [cAMP]i and also inhibited several pro-inflammatory effects induced by exogenous ABA on granulocytes and monocytes. Accordingly, these analogs could be suitable as novel putative anti-inflammatory compounds.

  4. Polyunsaturated fatty acid analogs act antiarrhythmically on the cardiac IKs channel

    DEFF Research Database (Denmark)

    Liin, Sara I.; Silverå Ejneby, Malin; Barro-Soria, Rene;

    2015-01-01

    charge at neutral pH, restore the sensitivity to open IKs channels. PUFA analogs with a positively charged head group inhibit IKs channels. These different PUFA analogs could be developed into drugs to treat cardiac arrhythmias. In support of this possibility, we show that PUFA analogs act...

  5. Suppression of adipose lipolysis by long-chain fatty acid analogs.

    Science.gov (United States)

    Kalderon, Bella; Azazmeh, Narmen; Azulay, Nili; Vissler, Noam; Valitsky, Michael; Bar-Tana, Jacob

    2012-05-01

    Agonist-induced lipolysis of adipose fat is robustly inhibited by insulin or by feedback inhibition by the long-chain fatty acids (LCFA) produced during lipolysis. However, the mode of action of LCFA in suppressing adipose lipolysis is not clear. β,β'-Tetramethyl hexadecanedioic acid (Mββ/ EDICA16) is a synthetic LCFA that is neither esterified into lipids nor β-oxidized, and therefore, it was exploited for suppressing agonist-induced lipolysis in analogy to natural LCFA. Mββ is shown here to suppress isoproterenol-induced lipolysis in the rat in vivo as well as in 3T3-L1 adipocytes. Inhibition of isoproterenol-induced lipolysis is due to decrease in isoproterenol-induced cAMP with concomitant inhibition of the phosphorylation of hormone-sensitive lipase and perilipin by protein kinase A. Suppression of cellular cAMP levels is accounted for by inhibition of the adenylate cyclase due to suppression of Raf1 expression by Mββ-activated AMPK. Suppression of Raf1 is further complemented by induction of components of the unfolded-protein-response by Mββ. Our findings imply genuine inhibition of agonist-induced adipose lipolysis by LCFA, independent of their β-oxidation or reesterification. Mββ suppression of agonist-induced lipolysis and cellular cAMP levels independent of the insulin transduction pathway may indicate that synthetic LCFA could serve as insulin mimetics in the lipolysis context under conditions of insulin resistance.

  6. Molecular simulation of N-acetylneuraminic acid analogs and molecular dynamics studies of cholera toxin-Neu5Gc complex.

    Science.gov (United States)

    Blessy, J Jino; Sharmila, D Jeya Sundara

    2015-01-01

    Cholera toxin (CT) is an AB5 protein complex secreted by the pathogen Vibrio cholera, which is responsible for cholera infection. N-acetylneuraminic acid (NeuNAc) is a derivative of neuraminic acid with nine-carbon backbone. NeuNAc is distributed on the cell surface mainly located in the terminal components of glycoconjugates, and also plays an important role in cell-cell interaction. In our current study, molecular docking and molecular dynamic (MD) simulations were implemented to identify the potent NeuNAc analogs with high-inhibitory activity against CT protein. Thirty-four NeuNAc analogs, modified in different positions C-1/C-2/C-4/C-5/C-7/C-8/C-9, were modeled and docked against the active site of CT protein. Among the 34 NeuNAc analogs, the analog Neu5Gc shows the least extra precision glide score of -9.52 and glide energy of -44.71 kcal/mol. NeuNAc analogs block the CT active site residues HIS:13, ASN:90, LYS:91, GLN:56, GLN:61, and TRP:88 through intermolecular hydrogen bonding. The MD simulation for CT-Neu5Gc docking complex was performed using Desmond. MD simulation of CT-Neu5Gc complex reveals the stable nature of docking interaction.

  7. Comparative effects of curcumin and its analog on alcohol- and polyunsaturated fatty acid-induced alterations in circulatory lipid profiles.

    Science.gov (United States)

    Rukkumani, Rajagopalan; Aruna, Kode; Varma, Penumathsa Suresh; Rajasekaran, Kallikat Narayanan; Menon, Venugopal P

    2005-01-01

    Excessive alcohol intake induces hyperlipidemia. Studies suggest that natural principles and their analogs are known to possess anti-hyperlipidemic properties. In the present work we tested the effect of curcumin, an active principle of turmeric (Curcuma longa), and a curcumin analog on alcohol- and thermally oxidized polyunsaturated fatty acid (deltaPUFA)- induced hyperlipidemia. Male albino Wistar rats were used for the experimental study. Anti-hyperlipidemic activity of curcumin and curcumin analog was evaluated by analyzing the levels of cholesterol, triglycerides (TGs), phospholipids (PLs), and free fatty acids (FFAs). The results showed that the levels of cholesterol, TGs, PLs, and FFAs were increased significantly in alcohol-, deltaPUFA-, and alcohol + deltaPUFA-treated groups, which were brought down significantly on treatment with either of the curcuminoids. Curcumin analog treatment was found to be more effective than curcumin treatment. From the results obtained, we conclude that both curcumin and its analog effectively protect the system against alcohol- and deltaPUFA-induced hyperlipidemia and are possible candidates for the treatment of hyperlipidemia.

  8. Synthesis and evaluation of L-glutamic acid analogs as potential anticancer agents

    Directory of Open Access Journals (Sweden)

    Viswanathan C

    2008-01-01

    Full Text Available Four N-(benzenesulfonyl-L-glutamic acid bis(p-substituted phenylhydrazides were synthesized and evaluated for anticancer activity in vitro in DU-145 and PC-3 prostate cancer and in COLO-205 colon cancer cell lines by MTT assay. The analog with the nitro group substitution exhibited potent activity (% Inhibition 84.7 and 72.0 in DU-145 and PC-3 respectively at 80 mg/ml concentration. Another series of substituted 1-(benzenesulfonyl-5-oxopyrrolidine 2-carboxamides (11a-f were synthesized and evaluated for anticancer activity in vitro in colon (COLO-205, breast (Zr-75-1 and prostate (PC-3 cancer cell lines by MTT assay using adriamycin as standard. Test compounds 11a-c showed potent activity (% Inhibition 61.2 to 79.2 at 20 mg/ml and 67.2 to 87.2 at 40 mg/ml in PC-3 cell line which is superior to the activity of Adriamycin. In comparison compounds 11d-f were less potent. In Zr-75-1 cell line 11a-e showed % inhibition ranging from 32.4 to 54.9 at 10 mg/ml concentration while in COLO-205 cell line 11a-f showed poor activity.

  9. Combined Kinetic Studies and Computational Analysis on Kojic Acid Analogs as Tyrosinase Inhibitors

    Directory of Open Access Journals (Sweden)

    Carlyle Ribeiro Lima

    2014-07-01

    Full Text Available Tyrosinase is a key enzyme in melanin synthesis and widely distributed in plants and animals tissues. In mammals, this enzyme is related to pigment production, involved in wound healing, primary immune response and it can also contribute to catecholamines synthesis in the brain. Consequently, tyrosinase enzyme represents an attractive and selective target in the field of the medicine, cosmetics and bio-insecticides. In this paper, experimental kinetics and computational analysis were used to study the inhibition of tyrosinase by analogous of Kojic acid. The main interactions occurring between inhibitors-tyrosinase complexes and the influence of divalent cation (Cu2+ in enzymatic inhibition were investigated by using molecular docking, molecular dynamic simulations and electrostatic binding free energy by using the Linear Interaction Energy (LIE method. The results showed that the electrostatic binding free energy are correlated with values of constant inhibition (r2 = 0.97.Thus, the model obtained here could contribute to future studies of this important system and, therefore, eventually facilitate development of tyrosinase inhibitors.

  10. Synthesis and Insecticidal Activity of Novel Camptothecin Derivatives Containing Analogs of Chrysanthemic Acid Moieties

    Institute of Scientific and Technical Information of China (English)

    DENG Li; ZHANG Lan; CAO Li-dong; XIE Ru-liang; ZHANG Yan-ning; HE Wei-zhi; JIANG Hong-yun

    2014-01-01

    Creating high-efifcient and environment-friendly pesticides is very important to produce the pollution free agriculture food and maintain the balance of the survival environmental of the human being. According to reports, camptothecin (CPT) and its derivatives are now being explored as a class of botanical insecticide in agriculture due to its novel mode of action. In order to improve the insecticidal activity of CPT, ten novel camptothecin (1) and 10-hydroxycamptothecin (2) derivatives (1a, 1b, 1c, 1d, 1e;2a, 2b, 2c, 2d, 2e) were designed and synthesized via esteriifcation with analogs of chrysanthemic acid, which have outstanding insecticidal activity. The results showed that compound 2a exhibited potent antifeeding effect and the best contact toxicity among the target compounds against the third-instar larvae of beet armyworm, Spodoptera exigua Hübner. Compound 2a was also found to be the most effective cytotoxic compound to the tested insect cell lines, IOZCAS-Spex-II, which were established from the fat bodies of S. exigua. It was proposed that the 10-hydroxyl group in the camptothecin derivatives is a key factor for the antifeeding activity of a compound. The nature of the substituents was considered the major factor in determining the insecticidal activity of these compounds.

  11. THz and mid-IR spectroscopy of interstellar ice analogs: methyl and carboxylic acid groups.

    Science.gov (United States)

    Ioppolo, S; McGuire, B A; Allodi, M A; Blake, G A

    2014-01-01

    A fundamental problem in astrochemistry concerns the synthesis and survival of complex organic molecules (COMs) throughout the process of star and planet formation. While it is generally accepted that most complex molecules and prebiotic species form in the solid phase on icy grain particles, a complete understanding of the formation pathways is still largely lacking. To take full advantage of the enormous number of available THz observations (e.g., Herschel Space Observatory, SOFIA, and ALMA), laboratory analogs must be studied systematically. Here, we present the THz (0.3-7.5 THz; 10-250 cm(-1)) and mid-IR (400-4000 cm(-1)) spectra of astrophysically-relevant species that share the same functional groups, including formic acid (HCOOH) and acetic acid (CH3COOH), and acetaldehyde (CH3CHO) and acetone ((CH3)2CO), compared to more abundant interstellar molecules such as water (H2O), methanol (CH3OH), and carbon monoxide (CO). A suite of pure and mixed binary ices are discussed. The effects on the spectra due to the composition and the structure of the ice at different temperatures are shown. Our results demonstrate that THz spectra are sensitive to reversible and irreversible transformations within the ice caused by thermal processing, suggesting that THz spectra can be used to study the composition, structure, and thermal history of interstellar ices. Moreover, the THz spectrum of an individual species depends on the functional group(s) within that molecule. Thus, future THz studies of different functional groups will help in characterizing the chemistry and physics of the interstellar medium (ISM).

  12. Design and Synthesis of an Inositol Phosphate Analog Based on Computational Docking Studies.

    Science.gov (United States)

    Peng, Zhenghong; Maxwell, David; Sun, Duoli; Ying, Yunming; Schuber, Paul T; Bhanu Prasad, Basvoju A; Gelovani, Juri; Yung, Wai-Kwan Alfred; Bornmann, William G

    2014-01-28

    A virtual library of 54 inositol analog mimics of In(1,4,5)P3 has been docked, scored, and ranked within the binding site of human inositol 1,4,5-trisphosphate 3-kinase A (IP3-3KA). Chemical synthesis of the best scoring structure that also met distance criteria for 3'-OH to -P in Phosphate has been attempted along with the synthesis of (1S,2R,3S,4S)-3-fluoro-2,4-dihydroxycyclohexanecarboxylic acid as an inositol analog, useful for non-invasive visualization and quantitation of IP3-3KA enzymatic activity.

  13. Acids and bases solvent effects on acid-base strenght

    CERN Document Server

    Cox, Brian G

    2013-01-01

    Acids and bases are ubiquitous in chemistry. Our understanding of them, however, is dominated by their behaviour in water. Transfer to non-aqueous solvents leads to profound changes in acid-base strengths and to the rates and equilibria of many processes: for example, synthetic reactions involving acids, bases and nucleophiles; isolation of pharmaceutical actives through salt formation; formation of zwitter- ions in amino acids; and chromatographic separation of substrates. This book seeks to enhance our understanding of acids and bases by reviewing and analysing their behaviour in non-aqueous solvents. The behaviour is related where possible to that in water, but correlations and contrasts between solvents are also presented.

  14. Formation of Amino Acid Precursors by Bombardment of Interstellar Ice Analogs with High Energy Heavy Ions

    Science.gov (United States)

    Kobayashi, Kensei; Mita, Hajime; Yoshida, Satoshi; Shibata, Hiromi; Enomoto, Shingo; Matsuda, Tomoyuki; Fukuda, Hitoshi; Kondo, Kotaro; Oguri, Yoshiyuki; Kebukawa, Yoko

    2016-07-01

    A wide variety of organic compounds have been detected in extraterrestrial bodies. It has been recognized that carbonaceous chondrites contain pristine amino acids [1]. There are several scenarios of the formation of such extraterrestrial amino acids or their precursors. Greenberg proposed a scenario that complex organic compounds were formed in interstellar ices in dense clouds, which were brought into solar system small bodies when the solar system was formed [2]. The ice mantles of interstellar dust particles (ISDs) in dense clouds are composed of H2O, CO, CH3OH, CH4, CO2, NH3, etc. In order to verify the scenario, a number of laboratory experiments have been conducted where interstellar ice analogs were irradiated with high-energy particles [3,4] or UV [5,6], and formation of complex organic compounds including amino acid precursors were detected in the products. Though ion-molecular reactions in gaseous phase and surface reactions on the ice mantles have been studied intensively, much less works on cosmic rays-induced reaction have been reported. In order to study possible formation of complex molecules in interstellar ices, frozen mixtures of water, methanol and ammonia with various mixing ratios were irradiated with high-energy heavy ions such as carbon ions (290 MeV/u) and neon ions (400 MeV/u) from HIMAC, NIRS, Japan. For comparison, gaseous mixtures of water, ammonia, carbon monoxide, carbon dioxide, and/or methane were irradiated with protons (2.5 MeV) from a Tandem accelerator, Tokyo Tech, Japan. Amino acids in the products were determined by cation exchange HPLC after acid hydrolysis. Products, both before and after acid hydrolysis, were also characterized by FT-IR and other techniques. Amino acids were detected in the hydrolyzed products after mixture of CH3OH, NH3 and H2O with various mixing ratios were irradiated with heavy ions, including when their mixing ratio was set close to the reported value of the interstellar ices (10:1:37). In the HIMAC

  15. Genome-wide screening for genes whose deletions confer sensitivity to mutagenic purine base analogs in yeast

    Directory of Open Access Journals (Sweden)

    Kozmin Stanislav G

    2005-06-01

    Full Text Available Abstract Background N-hydroxylated base analogs, such as 6-hydroxylaminopurine (HAP and 2-amino-6-hydroxylaminopurine (AHA, are strong mutagens in various organisms due to their ambiguous base-pairing properties. The systems protecting cells from HAP and related noncanonical purines in Escherichia coli include specialized deoxyribonucleoside triphosphatase RdgB, DNA repair endonuclease V, and a molybdenum cofactor-dependent system. Fewer HAP-detoxification systems have been identified in yeast Saccharomyces cerevisiae and other eukaryotes. Cellular systems protecting from AHA are unknown. In the present study, we performed a genome-wide search for genes whose deletions confer sensitivity to HAP and AHA in yeast. Results We screened the library of yeast deletion mutants for sensitivity to the toxic and mutagenic action of HAP and AHA. We identified novel genes involved in the genetic control of base analogs sensitivity, including genes controlling purine metabolism, cytoskeleton organization, and amino acid metabolism. Conclusion We developed a method for screening the yeast deletion library for sensitivity to the mutagenic and toxic action of base analogs and identified 16 novel genes controlling pathways of protection from HAP. Three of them also protect from AHA.

  16. Down-regulation of the caffeic acid O-methyltransferase gene in switchgrass reveals a novel monolignol analog

    Directory of Open Access Journals (Sweden)

    Tschaplinski Timothy J

    2012-09-01

    Full Text Available Abstract Background Down-regulation of the caffeic acid 3-O-methyltransferase EC 2.1.1.68 (COMT gene in the lignin biosynthetic pathway of switchgrass (Panicum virgatum resulted in cell walls of transgenic plants releasing more constituent sugars after pretreatment by dilute acid and treatment with glycosyl hydrolases from an added enzyme preparation and from Clostridium thermocellum. Fermentation of both wild-type and transgenic switchgrass after milder hot water pretreatment with no water washing showed that only the transgenic switchgrass inhibited C. thermocellum. Gas chromatography–mass spectrometry (GCMS-based metabolomics were undertaken on cell wall aqueous extracts to determine the nature of the microbial inhibitors. Results GCMS confirmed the increased concentration of a number of phenolic acids and aldehydes that are known inhibitors of microbial fermentation. Metabolomic analyses of the transgenic biomass additionally revealed the presence of a novel monolignol-like metabolite, identified as trans-3, 4-dimethoxy-5-hydroxycinnamyl alcohol (iso-sinapyl alcohol in both non-pretreated, as well as hot water pretreated samples. iso-Sinapyl alcohol and its glucoside were subsequently generated by organic synthesis and the identity of natural and synthetic materials were confirmed by mass spectrometric and NMR analyses. The additional novel presence of iso-sinapic acid, iso-sinapyl aldehyde, and iso-syringin suggest the increased activity of a para-methyltransferase, concomitant with the reduced COMT activity, a strict meta-methyltransferase. Quantum chemical calculations were used to predict the most likely homodimeric lignans generated from dehydration reactions, but these products were not evident in plant samples. Conclusions Down-regulation of COMT activity in switchgrass resulted in the accumulation of previously undetected metabolites resembling sinapyl alcohol and its related metabolites, but that are derived from para

  17. Biopharmaceutical Characterization and Bioavailability Study of a Tetrazole Analog of Clofibric Acid in Rat

    Directory of Open Access Journals (Sweden)

    Nancy Vara-Gama

    2017-02-01

    Full Text Available In the current investigation, the physicochemical, biopharmaceutical and pharmacokinetic characterization of a new clofibric acid analog (Compound 1 was evaluated. Compound 1 showed affinity by lipophilic phase in 1 to 5 pH interval, indicating that this compound would be absorbed favorably in duodenum or jejunum. Also, Compound 1 possess two ionic species, first above of pH 4.43 and, the second one is present over pH 6.08. The apparent permeability in everted sac rat intestine model was 8.73 × 10−6 cm/s in duodenum and 1.62 × 10−5 cm/s in jejunum, suggesting that Compound 1 has low permeability. Elimination constant after an oral administration of 50 μg/kg in Wistar rat was 1.81 h−1, absorption constant was 3.05 h−1, Cmax was 3.57 μg/mL at 0.33 h, AUC0–α was 956.54 μ/mL·h and distribution volume was 419.4 mL. To IV administration at the same dose, ke was 1.21 h−1, Vd was 399.6 mL and AUC0–α was 747.81 μ/mL·h. No significant differences were observed between pharmacokinetic parameters at every administration route. Bioavailability evaluated was 10.4%. Compound 1 is metabolized to Compound 2 probably by enzymatic hydrolysis, and it showed a half-life of 9.24 h. With these properties, Compound 1 would be considered as a prodrug of Compound 2 with potential as an antidiabetic and anti dyslipidemic agent.

  18. Recent Advances in Nucleic Acid Binding Aspects of Berberine Analogs and Implications for Drug Design.

    Science.gov (United States)

    Bhowmik, Debipreeta; Kumar, Gopinatha Suresh

    2016-01-01

    Berberine is one of the most widely known alkaloids belonging to the protoberberine group exhibiting myriad therapeutic properties. The anticancer potency of berberine appears to derive from its multiple actions including strong interaction with nucleic acids exhibiting adenine-thymine base pair specificity, inhibition of the enzymes topoisomerases and telomerases, and stabilizing the quadruplex structures. It was realized that the development of berberine as a potential anticancer agent necessitates enhancing its nucleic acid binding efficacy through appropriate structural modifications. More recently a number of such approaches have been attempted in various laboratories with great success. Several derivatives have been synthesized mostly with substitutions at the 8, 9 and 13 positions of the isoquinoline chromophore, and studied for enhanced nucleic acid binding activity. In this article, we present an up to date review of the details of the interaction of berberine and several of its important synthetic 8, 9 and 13 substituted derivatives with various nucleic acid structures reported recently. These studies provide interesting knowledge on the mode, mechanism, sequence and structural specificity of the binding of berberine derivatives and correlate structural and energetic aspects of the interaction providing better understanding of the structure- activity relations for designing and development of berberine based therapeutic agents with higher efficacy and therapeutic potential.

  19. A Loudness Function for Analog and Digital Sound Systems based on Equal Loudness Level Contours

    DEFF Research Database (Denmark)

    Nielsen, Sofus Birkedal

    2016-01-01

    frequency balance will been changed both for LL lower or higher than ML. The differences in ELLC ask for a level based equalization using fractional-order filters. A designing technique for both analog and digital fractional-order filters was developed. The analog solution is based on OPAMs and the digital......A new and better loudness compensation has been designed based on the differences between the Equal Loudness Level Contours (ELLC) in ISO 226:2003. Sound productions are normally being mixed at a high mixing level (ML) but often played at lower listening level (LL) which mean that the perceived...

  20. Using Australian Acidic Playa Lakes as Analogs for Phyllosilicate and Sulfate Depositional Environments on Mars

    Science.gov (United States)

    Baldridge, A. M.; Michalski, J.; Kargel, J.; Hook, S.; Marion, G.; Crowley, J.; Bridges, N.; Brown, A.; Ribeiro da Luz, B.; de Souza Filho, C. R.; Thomson, B.

    2008-12-01

    Recent work on the origin of martian sulfates and their relationship to phyllosilicate deposits suggest that these deposits formed in different eras of Mars' history, under distinct environmental conditions. In southwestern Meridiani Planum phyllosilicates exist in close proximity to sulfate deposits. One possible explanation for this relationship is that it is an unconformable stratigraphic sequence, representing a significant change in aqueous geochemical conditions over time. Specifically, it may be interpreted to record a change in environment from neutral pH aqueous alteration in the Noachian to an acidic evaporitic system in the late Noachian to the Hesperian. On Earth, two different geochemical systems need not be evoked to explain such chemical variation. Acidic playa lakes in Western Australia have large pH differences separated by only a few tens of meters and demonstrate how highly variable chemistries can coexist over short distances in natural environments. Playa lakes on Earth tend to be dominated by lateral flow of water and salts leading to lateral chemical variation. Heterogeneity of playa mineralogy in Australia is due to the varied source rocks of brines and the mixing of dilute oxidizing brines and freshwater with the saturated evaporitic brines. This is evidenced by the ferricretes in the near-shore environment and more soluble phases in basin interiors. Playa lakes on Mars would be much larger than their terrestrial counterparts, leading to the prevalence of large-scale surface and crustal advection of water and salt rather than short-distance lateral flow, except at lake boundaries. Little or no influx of freshwater would preclude the formation of playa rim (e.g., crater rim) ferricretes and silcretes. Instead, we expect to see mainly vertical facies changes, and any diachronous lateral facies changes are expected to occur on very large spatial scales. Comparison of high spatial resolution, hyperspectral airborne data for Australian playa

  1. FinFET Based Tunable Analog Circuit: Design and Analysis at 45 nm Technology

    Directory of Open Access Journals (Sweden)

    Ravindra Singh Kushwah

    2013-01-01

    Full Text Available We included a designing of low power tunable analog circuits built using independently driven FinFETs devices, where the controlling of the back gate provide the output on the front gate. We show that this could be an effective solution to conveniently tune the output of bulk CMOS analog circuits particularly for Schmitt trigger and operational transconductance amplifier circuits. FinFET devices can be used to increase the performance by reducing the leakage current and power dissipation, because front and back gates both are independently controlled. FinFET device has a higher controllability, resulting relatively high Ion/Ioff ratio. In this paper, we proposed a tunable analog circuit such as CMOS amplifier circuit, Schmitt trigger circuit, and operational transconductance amplifier circuit, these circuit blocks are necessary for low noise high performance ICs for analog applications. Gain, phase, group delay, and output response of analog tunable circuits have been discussed in this paper. The proposed FinFET based analog tunable circuits have been designed using Cadence Virtuoso tool at 45 nm.

  2. Feature evaluation and extraction based on neural network in analog circuit fault diagnosis

    Institute of Scientific and Technical Information of China (English)

    Yuan Haiying; Chen Guangju; Xie Yongle

    2007-01-01

    Choosing the right characteristic parameter is the key to fault diagnosis in analog circuit.The feature evaluation and extraction methods based on neural network are presented.Parameter evaluation of circuit features is realized by training results from neural network; the superior nonlinear mapping capability is competent for extracting fault features which are normalized and compressed subsequently.The complex classification problem on fault pattern recognition in analog circuit is transferred into feature processing stage by feature extraction based on neural network effectively, which improves the diagnosis efficiency.A fault diagnosis illustration validated this method.

  3. Doubling-resolution analog-to-digital conversion based on PIC18F45K80

    Directory of Open Access Journals (Sweden)

    Yueyang Yuan

    2014-08-01

    Full Text Available Aiming at the analog signal being converted into the digital with a higher precision, a method to improve the analog-to-digital converter (ADC resolution is proposed and described. Based on the microcomputer PIC18F45K80 in which the internal ADC modules are embedded, a circuit is designed for doubling the resolution of ADC. According to the circuit diagram, the mathematical formula for calculating this resolution is derived. The corresponding software and print circuit board assembly is also prepared. With the experiment, a 13 bit ADC is achieved based on the 12 bit ADC module predesigned in the PIC18F45K80.

  4. Larger bases and mixed analog/digital neural nets

    Energy Technology Data Exchange (ETDEWEB)

    Beiu, V.

    1998-12-31

    The paper overviews results dealing with the approximation capabilities of neural networks, and bounds on the size of threshold gate circuits. Based on an explicit numerical algorithm for Kolmogorov`s superpositions the authors show that minimum size neural networks--for implementing any Boolean function--have the identity function as the activation function. Conclusions and several comments on the required precision are ending the paper.

  5. Polyunsaturated fatty acids synergize with lipid droplet binding thalidomide analogs to induce oxidative stress in cancer cells

    Directory of Open Access Journals (Sweden)

    Madácsi Ramóna

    2010-06-01

    Full Text Available Abstract Background Cytoplasmic lipid-droplets are common inclusions of eukaryotic cells. Lipid-droplet binding thalidomide analogs (2,6-dialkylphenyl-4/5-amino-substituted-5,6,7-trifluorophthalimides with potent anticancer activities were synthesized. Results Cytotoxicity was detected in different cell lines including melanoma, leukemia, hepatocellular carcinoma, glioblastoma at micromolar concentrations. The synthesized analogs are non-toxic to adult animals up to 1 g/kg but are teratogenic to zebrafish embryos at micromolar concentrations with defects in the developing muscle. Treatment of tumor cells resulted in calcium release from the endoplasmic reticulum (ER, induction of reactive oxygen species (ROS, ER stress and cell death. Antioxidants could partially, while an intracellular calcium chelator almost completely diminish ROS production. Exogenous docosahexaenoic acid or eicosapentaenoic acid induced calcium release and ROS generation, and synergized with the analogs in vitro, while oleic acid had no such an effect. Gene expression analysis confirmed the induction of ER stress-mediated apoptosis pathway components, such as GADD153, ATF3, Luman/CREB3 and the ER-associated degradation-related HERPUD1 genes. Tumor suppressors, P53, LATS2 and ING3 were also up-regulated in various cell lines after drug treatment. Amino-phthalimides down-regulated the expression of CCL2, which is implicated in tumor metastasis and angiogenesis. Conclusions Because of the anticancer, anti-angiogenic action and the wide range of applicability of the immunomodulatory drugs, including thalidomide analogs, lipid droplet-binding members of this family could represent a new class of agents by affecting ER-membrane integrity and perturbations of ER homeostasis.

  6. Problems and Projects Based Approach For Analog Electronic Circuits' Course

    Directory of Open Access Journals (Sweden)

    Vahé Nerguizian

    2009-04-01

    Full Text Available New educational methods and approaches are recently introduced and implemented at several North American and European universities using Problems and Projects Based Approach (PPBA. The PPBA employs a teaching technique based mostly on competences/skills rather than only on knowledge. This method has been implemented and proven by several pedagogical instructors and authors at several educational institutions. This approach is used at different disciplines such as medicine, biology, engineering and many others. It has the advantage to improve the student's skills and the knowledge retention rate, and reflects the 21st century industrial/company needs and demands. Before implementing this approach to a course, a good resources preparation and planning is needed upfront by the responsible or instructor of the course to achieve the course and students related objectives. This paper presents the preparation, the generated documentation and the implementation of a pilot project utilizing PPBA education for a second year undergraduate electronic course over a complete semester, and for two different class groups (morning and evening groups. The outcome of this project (achieved goals, observed difficulties and lessons learned is presented based on different tools such as students 'in class' communication and feedback, different course evaluation forms and the professor/instructor feedback. Resources, challenges, difficulties and recommendations are also assessed and presented. The impact, the effect and the results (during and at the end of the academic fall session of the PPBA on students and instructor are discussed, validated, managed and communicated to help other instructor in taking appropriate approach decisions with respect to this new educational approach compared to the classical one.

  7. Investigations and design of pyridine-2-carboxylic acid thiazol-2-ylamide analogs as methionine aminopeptidase inhibitors using 3D-QSAR and molecular docking

    DEFF Research Database (Denmark)

    Hauser, Alexander Sebastian

    2014-01-01

    complexes, four new pyridine-2-carboxylic acid thiazol-2-ylamide analogs were designed. These analogs exhibit significantly better predicted activity than the reported molecules. The present work has implications for the development of novel antibiotics as potent MetAP inhibitors....

  8. Investigations and design of pyridine-2-carboxylic acid thiazol-2-ylamide analogs as methionine aminopeptidase inhibitors using 3D-QSAR and molecular docking

    DEFF Research Database (Denmark)

    Hauser, Alexander Sebastian

    2014-01-01

    complexes, four new pyridine-2-carboxylic acid thiazol-2-ylamide analogs were designed. These analogs exhibit significantly better predicted activity than the reported molecules. The present work has implications for the development of novel antibiotics as potent MetAP inhibitors....

  9. Model atmospheres for Mercury based on a lunar analogy

    Science.gov (United States)

    Hodges, R. R., Jr.

    1974-01-01

    Similarities in daytime spectral reflectivities and nighttime infrared emission from Mercury and the moon are shown to imply that the atmosphere of Mercury must be tenuous, like that of the moon. The theory of formation, transport, and loss in the lunar atmosphere is applied to Mercury. Models of the Hermian atmosphere at perihelion and aphelion are presented, based on the solar wind as the dominant source of gases. Only the noncondensable species - hydrogen, helium and neon - are considered. Of these, helium is the most abundant atmospheric gas, with maximum concentration of about 40,000,000 per cu cm at the nighttime surface. The maximum concentration of H2 is 6,000,000 per cu cm, and that of neon is 700,000 per cu cm.

  10. Comparison of Nootropic and Neuroprotective Features of Aryl-Substituted Analogs of Gamma-Aminobutyric Acid.

    Science.gov (United States)

    Tyurenkov, I N; Borodkina, L E; Bagmetova, V V; Berestovitskaya, V M; Vasil'eva, O S

    2016-02-01

    GABA analogs containing phenyl (phenibut) or para-chlorophenyl (baclofen) substituents demonstrated nootropic activity in a dose of 20 mg/kg: they improved passive avoidance conditioning, decelerated its natural extinction, and exerted antiamnestic effect on the models of amnesia provoked by scopolamine or electroshock. Tolyl-containing GABA analog (tolibut, 20 mg/kg) exhibited antiamnestic activity only on the model of electroshock-induced amnesia. Baclofen and, to a lesser extent, tolibut alleviated seizures provoked by electroshock, i.e. both agents exerted anticonvulsant effect. All examined GABA aryl derivatives demonstrated neuroprotective properties on the maximum electroshock model: they shortened the duration of coma and shortened the period of spontaneous motor activity recovery. In addition, these agents decreased the severity of passive avoidance amnesia and behavioral deficit in the open field test in rats exposed to electroshock. The greatest neuroprotective properties were exhibited by phenyl-containing GABA analog phenibut.

  11. LNA (locked nucleic acid) and analogs as triplex-forming oligonucleotides

    DEFF Research Database (Denmark)

    Højland, Torben; Kumar, Surender; Babu, Bolle Ravindra

    2007-01-01

    The triplex-forming abilities of some conformationally restricted nucleotide analogs are disclosed and compared herein. 2'-Amino-LNA monomers proved to be less stabilising to triplexes than LNA monomers when incorporated into a triplex-forming third strand. N2'-functionalisation of 2'-amino......-LNA monomers with a glycyl unit induced the formation of exceptionally stable triplexes. Nucleotide analogs containing a C2',C3'-oxymethylene linker (E-type furanose conformation) or a C2',C4'-propylene linker (N-type furanose conformation) had no significant effect on triplex stability proving...

  12. A novel prediction method about single components of analog circuits based on complex field modeling.

    Science.gov (United States)

    Zhou, Jingyu; Tian, Shulin; Yang, Chenglin

    2014-01-01

    Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator) calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits' single components. At last, it uses particle filter (PF) to update parameters for the model and predicts remaining useful performance (RUP) of analog circuits' single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments.

  13. A Novel Prediction Method about Single Components of Analog Circuits Based on Complex Field Modeling

    Directory of Open Access Journals (Sweden)

    Jingyu Zhou

    2014-01-01

    Full Text Available Few researches pay attention to prediction about analog circuits. The few methods lack the correlation with circuit analysis during extracting and calculating features so that FI (fault indicator calculation often lack rationality, thus affecting prognostic performance. To solve the above problem, this paper proposes a novel prediction method about single components of analog circuits based on complex field modeling. Aiming at the feature that faults of single components hold the largest number in analog circuits, the method starts with circuit structure, analyzes transfer function of circuits, and implements complex field modeling. Then, by an established parameter scanning model related to complex field, it analyzes the relationship between parameter variation and degeneration of single components in the model in order to obtain a more reasonable FI feature set via calculation. According to the obtained FI feature set, it establishes a novel model about degeneration trend of analog circuits’ single components. At last, it uses particle filter (PF to update parameters for the model and predicts remaining useful performance (RUP of analog circuits’ single components. Since calculation about the FI feature set is more reasonable, accuracy of prediction is improved to some extent. Finally, the foregoing conclusions are verified by experiments.

  14. Diagnosis of soft faults in analog integrated circuits based on fractional correlation

    Institute of Scientific and Technical Information of China (English)

    Deng Yong; Shi Yibing; Zhang Wei

    2012-01-01

    Aiming at the problem of diagnosing soft faults in analog integrated circuits,an approach based on fractional correlation is proposed.First,the Volterra series of the circuit under test (CUT) decomposed by the fractional wavelet packet are used to calculate the fractional correlation functions.Then,the calculated fractional correlation functions are used to form the fault signatures of the CUT.By comparing the fault signatures,the different soft faulty conditions of the CUT are identified and the faults are located.Simulations of benchmark circuits illustrate the proposed method and validate its effectiveness in diagnosing soft faults in analog integrated circuits.

  15. A MEMS-Based Power-Scalable Hearing Aid Analog Front End.

    Science.gov (United States)

    Deligoz, I; Naqvi, S R; Copani, T; Kiaei, S; Bakkaloglu, B; Sang-Soo Je; Junseok Chae

    2011-06-01

    A dual-channel directional digital hearing aid front end using microelectromechanical-systems microphones, and an adaptive-power analog processing signal chain are presented. The analog front end consists of a double differential amplifier-based capacitance-to-voltage conversion circuit, 40-dB variable gain amplifier (VGA) and a power-scalable continuous time sigma delta analog-to-digital converter (ADC), with 68-dB signal-to-noise ratio dissipating 67 μ W from a 1.2-V supply. The MEMS microphones are fabricated using a standard surface micromachining technology. The VGA and power-scalable ADC are fabricated on a 0.25-μ m complementary metal-oxide semciconductor TSMC process.

  16. Mixing Problem Based Learning And Conventional Teaching Methods In An Analog Electronics Course

    NARCIS (Netherlands)

    Podges, J.M.; Kommers, P.A.M.; Winnips, K.; Joolingen, van W.R.

    2014-01-01

    This study, undertaken at the Walter Sisulu University of Technology (WSU) in South Africa, describes how problem-based learning (PBL) affects the first year ‘analog electronics course’, when PBL and the lecturing mode is compared. Problems were designed to match real-life situations. Data betwee

  17. Mixing Problem Based Learning And Conventional Teaching Methods In An Analog Electronics Course

    NARCIS (Netherlands)

    Podges, J.M.; Kommers, Petrus A.M.; Winnips, K.; van Joolingen, Wouter

    2014-01-01

    This study, undertaken at the Walter Sisulu University of Technology (WSU) in South Africa, describes how problem-based learning (PBL) affects the first year ‘analog electronics course’, when PBL and the lecturing mode is compared. Problems were designed to match real-life situations. Data between

  18. Analogical and Category-Based Inference: A Theoretical Integration with Bayesian Causal Models

    Science.gov (United States)

    Holyoak, Keith J.; Lee, Hee Seung; Lu, Hongjing

    2010-01-01

    A fundamental issue for theories of human induction is to specify constraints on potential inferences. For inferences based on shared category membership, an analogy, and/or a relational schema, it appears that the basic goal of induction is to make accurate and goal-relevant inferences that are sensitive to uncertainty. People can use source…

  19. Property-Based Monitoring of Analog and Mixed-Signal Systems

    Science.gov (United States)

    Havlicek, John; Little, Scott; Maler, Oded; Nickovic, Dejan

    In the recent past, there has been a steady growth of the market for consumer embedded devices such as cell phones, GPS and portable multimedia systems. In embedded systems, digital, analog and software components are combined on a single chip, resulting in increasingly complex designs that introduce richer functionality on smaller devices. As a consequence, the potential insertion of errors into a design becomes higher, yielding an increasing need for automated analog and mixed-signal validation tools. In the purely digital setting, formal verification based on properties expressed in industrial specification languages such as PSL and SVA is nowadays successfully integrated in the design flow. On the other hand, the validation of analog and mixed-signal systems still largely depends on simulation-based, ad-hoc methods. In this tutorial, we consider some ingredients of the standard verification methodology that can be successfully exported from digital to analog and mixed-signal setting, in particular property-based monitoring techniques. Property-based monitoring is a lighter approach to the formal verification, where the system is seen as a "black-box" that generates sets of traces, whose correctness is checked against a property, that is its high-level specification. Although incomplete, monitoring is effectively used to catch faults in systems, without guaranteeing their full correctness.

  20. Choleretic effect of structural analogs of valproic acid in the rat.

    Science.gov (United States)

    Watkins, J B; Klaassen, C D

    1983-03-01

    A comparison of structure-choleretic activity relationship has been made for several branched- and straight-chain carboxylic acids including valproic acid. Cumulative bile flow was 13.8, 23.8, 29.4 and 14.9 ml/4hr/kg body weight for dimethyl-, diethyl-, dipropyl- (valproic acid), and dibutyl-acetic acid, respectively, after iv administration of approximately equimolar doses (1100 mumoles/kg). Except for dibutylacetic acid, maximal bile flow increased from control rates of 50-60 to 120-140 microliters/min/kg. Administration of higher doses of 2,2-dimethylbutanoic acid and 2-ethylbutanoic acid did not increase maximal bile flow above 125-140 microliters/min/kg but did prolong the duration of choleresis. Maximal and cumulative bile flows increased with length of carboxylic acid chain for 2,2-dimethyl substituted acids (2,2-dimethylacetic acid to 2,2-dimethylbutanoic acid). If the two methyl groups were on C-3 (3-methylbutanoic acid), no change in bile flow was observed. Straight-chain acids from C-5 to C-11 and pent-4-enoic acid did not alter bile flow. Thus, the effectiveness of several branched-chain carboxylic acids as choleretics parallel their ability as anticonvulsants. In contrast, the straight-chain acids which cause central nervous system depression have no choleretic activity.

  1. Communication disruption of guava moth (Coscinoptycha improbana) using a pheromone analog based on chain length.

    Science.gov (United States)

    Suckling, D M; Dymock, J J; Park, K C; Wakelin, R H; Jamieson, L E

    2013-09-01

    The guava moth, Coscinoptycha improbana, an Australian species that infests fruit crops in commercial and home orchards, was first detected in New Zealand in 1997. A four-component pheromone blend was identified but is not yet commercially available. Using single sensillum recordings from male antennae, we established that the same olfactory receptor neurons responded to two guava moth sex pheromone components, (Z)-11-octadecen-8-one and (Z)-12-nonadecen-9-one, and to a chain length analog, (Z)-13-eicosen-10-one, the sex pheromone of the related peach fruit moth, Carposina sasakii. We then field tested whether this non-specificity of the olfactory neurons might enable disruption of sexual communication by the commercially available analog, using male catch to synthetic lures in traps in single-tree, nine-tree and 2-ha plots. A disruptive pheromone analog, based on chain length, is reported for the first time. Trap catches for guava moth were disrupted by three polyethylene tubing dispensers releasing the analog in single-tree plots (86% disruption of control catches) and in a plots of nine trees (99% disruption). Where peach fruit moth pheromone dispensers were deployed at a density of 1000/ha in two 2-ha areas, pheromone traps for guava moth were completely disrupted for an extended period (up to 470 days in peri-urban gardens in Mangonui and 422 days in macadamia nut orchards in Kerikeri). In contrast, traps in untreated areas over 100 m away caught 302.8 ± 128.1 moths/trap in Mangonui and 327.5 ± 78.5 moths/ trap in Kerikeri. The longer chain length in the pheromone analog has greater longevity than the natural pheromone due to its lower volatility. Chain length analogs may warrant further investigation for mating disruption in Lepidoptera, and screening using single-sensillum recording is recommended.

  2. A Case Study Analysing the Process of Analogy-Based Learning in a Teaching Unit about Simple Electric Circuits

    Science.gov (United States)

    Paatz, Roland; Ryder, James; Schwedes, Hannelore; Scott, Philip

    2004-01-01

    The purpose of this case study is to analyse the learning processes of a 16-year-old student as she learns about simple electric circuits in response to an analogy-based teaching sequence. Analogical thinking processes are modelled by a sequence of four steps according to Gentner's structure mapping theory (activate base domain, postulate local…

  3. Palmitic acid analogs exhibit nanomolar binding affinity for the HIV-1 CD4 receptor and nanomolar inhibition of gp120-to-CD4 fusion.

    Directory of Open Access Journals (Sweden)

    Elena E Paskaleva

    Full Text Available BACKGROUND: We recently reported that palmitic acid (PA is a novel and efficient CD4 fusion inhibitor to HIV-1 entry and infection. In the present report, based on in silico modeling of the novel CD4 pocket that binds PA, we describe discovery of highly potent PA analogs with increased CD4 receptor binding affinities (K(d and gp120-to-CD4 inhibition constants (K(i. The PA analogs were selected to satisfy Lipinski's rule of drug-likeness, increased solubility, and to avoid potential cytotoxicity. PRINCIPAL FINDINGS: PA analog 2-bromopalmitate (2-BP was most efficacious with K(d approximately 74 nM and K(i approximately 122 nM, ascorbyl palmitate (6-AP exhibited slightly higher K(d approximately 140 nM and K(i approximately 354 nM, and sucrose palmitate (SP was least efficacious binding to CD4 with K(d approximately 364 nM and inhibiting gp120-to-CD4 binding with K(i approximately 1486 nM. Importantly, PA and its analogs specifically bound to the CD4 receptor with the one to one stoichiometry. SIGNIFICANCE: Considering observed differences between K(i and K(d values indicates clear and rational direction for improving inhibition efficacy to HIV-1 entry and infection. Taken together this report introduces a novel class of natural small molecules fusion inhibitors with nanomolar efficacy of CD4 receptor binding and inhibition of HIV-1 entry.

  4. PHYSIOLOGY OF ACID BASE BALANCE

    Directory of Open Access Journals (Sweden)

    Awati

    2014-12-01

    Full Text Available Acid-base, electrolyte, and metabolic disturbances are common in the intensive care unit. Almost all critically ill patients often suffer from compound acid-base and electrolyte disorders. Successful evaluation and management of such patients requires recognition of common patterns (e.g., metabolic acidosis and the ability to dissect one disorder from another. The intensivists needs to identify and correct these condition with the easiest available tools as they are the associated with multiorgan failure. Understanding the elements of normal physiology in these areas is very important so as to diagnose the pathological condition and take adequate measures as early as possible. Arterial blood gas analysis is one such tool for early detection of acid base disorder. Physiology of acid base is complex and here is the attempt to simplify it in our day to day application for the benefit of critically ill patients.

  5. Production of tranilast [N-(3',4'-dimethoxycinnamoyl)-anthranilic acid] and its analogs in yeast Saccharomyces cerevisiae.

    Science.gov (United States)

    Eudes, Aymerick; Baidoo, Edward E K; Yang, Fan; Burd, Helcio; Hadi, Masood Z; Collins, F William; Keasling, Jay D; Loqué, Dominique

    2011-02-01

    Biological synthesis of therapeutic drugs beneficial for human health using microbes offers an alternative production strategy to the methods that are commonly employed such as direct extraction from source organisms or chemical synthesis. In this study, we evaluated the potential for yeast (Saccharomyces cerevisiae) to be used as a catalyst for the synthesis of tranilast and various tranilast analogs (cinnamoyl anthranilates). Several studies have demonstrated that these phenolic amides have antioxidant properties and potential therapeutic benefits including antiinflammatory, antiproliferative, and antigenotoxic effects. The few cinnamoyl anthranilates naturally produced in plants such as oats and carnations result from the coupling of various hydroxycinnamoyl-CoAs to anthranilic acid. In order to achieve the microbial production of tranilast and several of its analogs, we engineered a yeast strain to co-express a 4-coumarate/CoA ligase (4CL, EC 6.2.1.12) from Arabidopsis thaliana and a hydroxycinnamoyl/benzoyl-CoA/anthranilate N-hydroxycinnamoyl/benzoyltransferase (HCBT, EC 2.3.1.144) from Dianthus caryophyllus. This modified yeast strain allowed us to produce tranilast and 26 different cinnamoyl anthranilate molecules within a few hours after exogenous supply of various combinations of cinnamic acids and anthranilate derivatives. Our data demonstrate the feasibility of rapidly producing a wide range of defined cinnamoyl anthranilates in yeast and underline a potential for the biological designed synthesis of naturally and non-naturally occurring molecules.

  6. ANALOG I/O MODULE TEST SYSTEM BASED ON EPICS CA PROTOCOL AND ACTIVEX CA INTERFACE

    Energy Technology Data Exchange (ETDEWEB)

    YENG,YHOFF,L.

    2003-10-13

    Analog input (ADC) and output (DAC) modules play a substantial role in device level control of accelerator and large experiment physics control system. In order to get the best performance some features of analog modules including linearity, accuracy, crosstalk, thermal drift and so on have to be evaluated during the preliminary design phase. Gain and offset error calibration and thermal drift compensation (if needed) may have to be done in the implementation phase as well. A natural technique for performing these tasks is to interface the analog VO modules and GPIB interface programmable test instruments with a computer, which can complete measurements or calibration automatically. A difficulty is that drivers of analog modules and test instruments usually work on totally different platforms (vxworks VS Windows). Developing new test routines and drivers for testing instruments under VxWorks (or any other RTOS) platform is not a good solution because such systems have relatively poor user interface and developing such software requires substantial effort. EPICS CA protocol and ActiveX CA interface provide another choice, a PC and LabVIEW based test system. Analog 110 module can be interfaced from LabVIEW test routines via ActiveX CA interface. Test instruments can be controlled via LabVIEW drivers, most of which are provided by instrument vendors or by National Instruments. Labview also provides extensive data analysis and process functions. Using these functions, users can generate powerful test routines very easily. Several applications built for Spallation Neutron Source (SNS) Beam Loss Monitor (BLM) system are described in this paper.

  7. The Effects of Trivalent Lanthanide Cationization on the Electron Transfer Dissociation of Acidic Fibrinopeptide B and its Analogs

    Science.gov (United States)

    Commodore, Juliette J.; Cassady, Carolyn J.

    2016-09-01

    Electrospray ionization (ESI) on mixtures of acidic fibrinopeptide B and two peptide analogs with trivalent lanthanide salts generates [M + Met + H]4+, [M + Met]3+, and [M + Met -H]2+, where M = peptide and Met = metal (except radioactive promethium). These ions undergo extensive and highly efficient electron transfer dissociation (ETD) to form metallated and non-metallated c- and z-ions. All metal adducted product ions contain at least two acidic sites, which suggest attachment of the lanthanide cation at the side chains of one or more acidic residues. The three peptides undergo similar fragmentation. ETD on [M + Met + H]4+ leads to cleavage at every residue; the presence of both a metal ion and an extra proton is very effective in promoting sequence-informative fragmentation. Backbone dissociation of [M + Met]3+ is also extensive, although cleavage does not always occur between adjacent glutamic acid residues. For [M + Met - H ]2+, a more limited range of product ions form. All lanthanide metal peptide complexes display similar fragmentation except for europium (Eu). ETD on [M + Eu - H]2+ and [M + Eu]3+ yields a limited amount of peptide backbone cleavage; however, [M + Eu + H]4+ dissociates extensively with cleavage at every residue. With the exception of the results for Eu(III), metallated peptide ion formation by ESI, ETD fragmentation efficiencies, and product ion formation are unaffected by the identity of the lanthanide cation. Adduction with trivalent lanthanide metal ions is a promising tool for sequence analysis of acidic peptides by ETD.

  8. Wideband Analog Transmission System Based on the External Intensity Electro-Optic Modulator

    Directory of Open Access Journals (Sweden)

    Jiri Svarny

    2016-01-01

    Full Text Available The work deals with design and integration of an analog electro-optic transmission system suitable for some specialized tasks of diagnostics and measurements. The system is based on principle of external intensity modulation of fiber guided laser radiation. Besides wideband and almost lossless transmission the system tolerates extreme length of the transmitting medium and ensures ultimate galvanic barrier between the input and output.

  9. Elevated Levels of DNA Strand Breaks Induced by a Base Analog in the Human Cell Line with the P32T ITPA Variant

    Directory of Open Access Journals (Sweden)

    Irina S.-R. Waisertreiger

    2010-01-01

    Full Text Available Base analogs are powerful antimetabolites and dangerous mutagens generated endogenously by oxidative stress, inflammation, and aberrant nucleotide biosynthesis. Human inosine triphosphate pyrophosphatase (ITPA hydrolyzes triphosphates of noncanonical purine bases (i.e., ITP, dITP, XTP, dXTP, or their mimic: 6-hydroxyaminopurine (HAP deoxynucleoside triphosphate and thus regulates nucleotide pools and protects cells from DNA damage. We demonstrate that the model purine base analog HAP induces DNA breaks in human cells and leads to elevation of levels of ITPA. A human polymorphic allele of the ITPA, 94C->A encodes for the enzyme with a P32T amino-acid change and leads to accumulation of nonhydrolyzed ITP. The polymorphism has been associated with adverse reaction to purine base-analog drugs. The level of both spontaneous and HAP-induced DNA breaks is elevated in the cell line with the ITPA P32T variant. The results suggested that human ITPA plays a pivotal role in the protection of DNA from noncanonical purine base analogs.

  10. Imidase catalyzing desymmetric imide hydrolysis forming optically active 3-substituted glutaric acid monoamides for the synthesis of gamma-aminobutyric acid (GABA) analogs.

    Science.gov (United States)

    Nojiri, Masutoshi; Hibi, Makoto; Shizawa, Hiroaki; Horinouchi, Nobuyuki; Yasohara, Yoshihiko; Takahashi, Satomi; Ogawa, Jun

    2015-12-01

    The recent use of optically active 3-substituted gamma-aminobutyric acid (GABA) analogs in human therapeutics has identified a need for an efficient, stereoselective method of their synthesis. Here, bacterial strains were screened for enzymes capable of stereospecific hydrolysis of 3-substituted glutarimides to generate (R)-3-substituted glutaric acid monoamides. The bacteria Alcaligenes faecalis NBRC13111 and Burkholderia phytofirmans DSM17436 were discovered to hydrolyze 3-(4-chlorophenyl) glutarimide (CGI) to (R)-3-(4-chlorophenyl) glutaric acid monoamide (CGM) with 98.1% enantiomeric excess (e.e.) and 97.5% e.e., respectively. B. phytofirmans DSM17436 could also hydrolyze 3-isobutyl glutarimide (IBI) to produce (R)-3-isobutyl glutaric acid monoamide (IBM) with 94.9% e.e. BpIH, an imidase, was purified from B. phytofirmans DSM17436 and found to generate (R)-CGM from CGI with specific activity of 0.95 U/mg. The amino acid sequence of BpIH had a 75% sequence identity to that of allantoinase from A. faecalis NBRC13111 (AfIH). The purified recombinant BpIH and AfIH catalyzed (R)-selective hydrolysis of CGI and IBI. In addition, a preliminary investigation of the enzymatic properties of BpIH and AfIH revealed that both enzymes were stable in the range of pH 6-10, with an optimal pH of 9.0, stable at temperatures below 40 °C, and were not metalloproteins. These results indicate that the use of this class of hydrolase to generate optically active 3-substituted glutaric acid monoamide could simplify the production of specific chiral GABA analogs for drug therapeutics.

  11. Nucleic Acid Extraction from Synthetic Mars Analog Soils for in situ Life Detection

    Science.gov (United States)

    Mojarro, Angel; Ruvkun, Gary; Zuber, Maria T.; Carr, Christopher E.

    2017-08-01

    Biological informational polymers such as nucleic acids have the potential to provide unambiguous evidence of life beyond Earth. To this end, we are developing an automated in situ life-detection instrument that integrates nucleic acid extraction and nanopore sequencing: the Search for Extra-Terrestrial Genomes (SETG) instrument. Our goal is to isolate and determine the sequence of nucleic acids from extant or preserved life on Mars, if, for example, there is common ancestry to life on Mars and Earth. As is true of metagenomic analysis of terrestrial environmental samples, the SETG instrument must isolate nucleic acids from crude samples and then determine the DNA sequence of the unknown nucleic acids. Our initial DNA extraction experiments resulted in low to undetectable amounts of DNA due to soil chemistry-dependent soil-DNA interactions, namely adsorption to mineral surfaces, binding to divalent/trivalent cations, destruction by iron redox cycling, and acidic conditions. Subsequently, we developed soil-specific extraction protocols that increase DNA yields through a combination of desalting, utilization of competitive binders, and promotion of anaerobic conditions. Our results suggest that a combination of desalting and utilizing competitive binders may establish a "universal" nucleic acid extraction protocol suitable for analyzing samples from diverse soils on Mars.

  12. Low Voltage Analog Circuit Design Based on the Flipped Voltage Follower

    Directory of Open Access Journals (Sweden)

    Neeraj Yadav

    2012-03-01

    Full Text Available The desire for portability of electronics equipment generated a need for low power system in battery products like hearing aids, implantable cardiac pacemakers, cell phones and hand held multimedia terminals. Low voltage analog circuit design differs considerably from those of high voltage analog circuit design. This paper present the basic cell knows as “flipped voltage follower” for low voltage/ low power operation. The detailed classification of basic topologies derived from the FVF cell is presented and there is a low voltage current mirror based on FVF cell has been presented. All the Circuit has been simulated using Hspice tool 0.18µm CMOS Technology. Different quality factors such as frequency response, power consumption are considered. A compression also made between previous current mirror and new designed current mirror. The layout of the current mirror has been also designed using Cadence tool.

  13. Induction of porcine host defense peptide gene expression by short-chain fatty acids and their analogs.

    Directory of Open Access Journals (Sweden)

    Xiangfang Zeng

    Full Text Available Dietary modulation of the synthesis of endogenous host defense peptides (HDPs represents a novel antimicrobial approach for disease control and prevention, particularly against antibiotic-resistant infections. However, HDP regulation by dietary compounds such as butyrate is species-dependent. To examine whether butyrate could induce HDP expression in pigs, we evaluated the expressions of a panel of porcine HDPs in IPEC-J2 intestinal epithelial cells, 3D4/31 macrophages, and primary monocytes in response to sodium butyrate treatment by real-time PCR. We revealed that butyrate is a potent inducer of multiple, but not all, HDP genes. Porcine β-defensin 2 (pBD2, pBD3, epididymis protein 2 splicing variant C (pEP2C, and protegrins were induced markedly in response to butyrate, whereas pBD1 expression remained largely unaltered in any cell type. Additionally, a comparison of the HDP-inducing efficacy among saturated free fatty acids of different aliphatic chain lengths revealed that fatty acids containing 3-8 carbons showed an obvious induction of HDP expression in IPEC-J2 cells, with butyrate being the most potent and long-chain fatty acids having only a marginal effect. We further investigated a panel of butyrate analogs for their efficacy in HDP induction, and found glyceryl tributyrate, benzyl butyrate, and 4-phenylbutyrate to be comparable with butyrate. Identification of butyrate and several analogs with a strong capacity to induce HDP gene expression in pigs provides attractive candidates for further evaluation of their potential as novel alternatives to antibiotics in augmenting innate immunity and disease resistance of pigs.

  14. Conformation Analysis and Comparison of Epristeride(17β-N-t-Butylcarboxamide-androst-3,5-diene-3-carboxylic Acid) and Its Analogs

    Institute of Scientific and Technical Information of China (English)

    YAO Li-xin

    2005-01-01

    Conformations of Epristeride(17-β-N-t-butylcarboxamide-androst-3,5-diene-3-carboxylic acid) and its analogs were analyzed with the random search method and compared by means of the methods for steroid conformers, Connolly surfaces, dihedral angles, and molecular accessibility probes with protons, hydroxyl and methyl groups contained simultaneously. Analog d is different from others, which is in accordance with the preliminary clinical trial results under double blind conditions.

  15. Structure-property study of the Raman spectroscopy detection of fusaric acid and analogs

    Science.gov (United States)

    Food security can benefit from the development of selective methods to detect toxins. Fusaric acid is a mycotoxin produced by certain fungi occasionally found in agricultural commodities. Raman spectroscopy allows selective detection of analytes associated with certain spectral characteristics relat...

  16. Molten fatty acid based microemulsions.

    Science.gov (United States)

    Noirjean, Cecile; Testard, Fabienne; Dejugnat, Christophe; Jestin, Jacques; Carriere, David

    2016-06-21

    We show that ternary mixtures of water (polar phase), myristic acid (MA, apolar phase) and cetyltrimethylammonium bromide (CTAB, cationic surfactant) studied above the melting point of myristic acid allow the preparation of microemulsions without adding a salt or a co-surfactant. The combination of SANS, SAXS/WAXS, DSC, and phase diagram determination allows a complete characterization of the structures and interactions between components in the molten fatty acid based microemulsions. For the different structures characterized (microemulsion, lamellar or hexagonal phases), a similar thermal behaviour is observed for all ternary MA/CTAB/water monophasic samples and for binary MA/CTAB mixtures without water: crystalline myristic acid melts at 52 °C, and a thermal transition at 70 °C is assigned to the breaking of hydrogen bounds inside the mixed myristic acid/CTAB complex (being the surfactant film in the ternary system). Water determines the film curvature, hence the structures observed at high temperature, but does not influence the thermal behaviour of the ternary system. Myristic acid is partitioned in two "species" that behave independently: pure myristic acid and myristic acid associated with CTAB to form an equimolar complex that plays the role of the surfactant film. We therefore show that myristic acid plays the role of a solvent (oil) and a co-surfactant allowing the fine tuning of the structure of oil and water mixtures. This solvosurfactant behaviour of long chain fatty acid opens the way for new formulations with a complex structure without the addition of any extra compound.

  17. A language based on analogy to communicate cultural concepts in SETI

    Science.gov (United States)

    Musso, Paolo

    2011-02-01

    The present paper is a synthesis of three presentation given by myself at the Toulouse IAC 2001 ( Analogy as a tool to communicate abstract concepts in SETI), the Bremen IAC 2003 ( From maths to culture: towards an effective message), and the Vancouver IAC 2004 ( Philosophical and religious implications of extraterrestrial intelligent life). Its aim is to find a way to make our cultural concepts understandable to hypothetical extraterrestrials (ETs) in a SETI communication. First of all, I expose the reasons why I think that analogy could be a good tool for this purpose. Then, I try to show that this is possible only in the context of an integrated language, using both abstract symbols and pictures, also sketching two practical examples about some basic concepts of our moral and religious tradition. Further studies are required to determine whether this method could be extended to the higher-level abstract concepts in the other fields of our culture. Finally, I discuss the possible role of mathematics, logic and natural science in the construction of an analogy-based language for interstellar messages with a cultural content and a possible way of managing this matter from a social point of view.

  18. Models of Metabolic Community Structure in Martian Habitable Environments: Constraints from a Terrestrial Analog Acid-Sulfate Fumarole Environment, Cerro Negro Volcano, Nicaragua

    Science.gov (United States)

    Rogers, K. L.; McCollom, T. M.; Hynek, B. M.

    2014-12-01

    Microbial habitability in extreme environments on Earth is described by microscale geochemical conditions that constrain metabolic niches in concert with long-term habitat stability that is governed by dynamic geologic processes. Using terrestrial analogs to identify habitable martian environments requires correlating microscale geochemical constraints with reconstructions of past martian environments that are based on global-scale observations. While past martian environments can be characterized by primary parameters (e.g. pH, redox, mineralogy, thermal history), microbial habitability on Earth is a complex function of both primary and derived parameters (e.g. metabolic reaction energetics, chemical & thermal gradients, flow dynamics). In recent years we have been investigating acid-sulfate fumaroles at the Mars analog site, Cerro Negro Volcano, Nicaragua, where habitability is constrained by steep thermal gradients, spatially- and temporally-variable vent dynamics, and limited water and nutrient availability. The most common niche identified thus far is found in fumaroles that host mixed photosynthetic and chemosynthetic endolithic microbial communities. One such endolith is dominated by acidic red algae (Cyanidiales), aerobic bacterial heterotrophs (Ktedonobacteria), and archaeal thermoacidophiles (Hyperthermus, Caldisphaera, and Thermofilum). An analysis of the metabolic structure suggests that primary production by the red algae supports the growth of heterotrophic thermoacidophiles. Diversification among the chemoheterotrophs with respect to temperature and oxygen tolerance suggests community adaptation to environmental gradients or variable venting dynamics. Furthermore, individual cells within the endolith are silica-encrusted, providing the possibility for biosignature formation and preservation. Putative hydrothermal environments on early Mars with similar conditions could have supported endolithic communities with comparable metabolic strategies. Even

  19. Experimental Acid Weathering of Fe-Bearing Mars Analog Minerals and Rocks: Implications for Aqueous Origin of Hematite-Bearing Sediments in Meridiani Planum, Mars

    Science.gov (United States)

    Golden, D. C.; Koster, A. M.; Ming, D. W.; Morris, R. V.; Mertzman, S. A.

    2011-01-01

    A working hypothesis for Meridiani evaporite formation involves the evaporation of fluids derived from acid weathering of Martian basalts and subsequent diagenesis [1, 2]. However, there are no reported experimental studies for the formation of jarosite and gray hematite (spherules), which are characteristic of Meridiani rocks from Mars analog precursor minerals. A terrestrial analog for hematite spherule formation from basaltic rocks under acidic hydrothermal conditions has been reported [3], and we have previously shown that the hematite spherules and jarosite can be synthetically produced in the laboratory using Fe3+ -bearing sulfate brines under hydrothermal conditions [4]. Here we expand and extend these studies by reacting Mars analog minerals with sulfuric acid to form Meridiani-like rock-mineral compositions. The objective of this study is to provide environmental constraints on past aqueous weathering of basaltic materials on Mars.

  20. The AMP analog AICAR modulates the Treg/Th17 axis through enhancement of fatty acid oxidation.

    Science.gov (United States)

    Gualdoni, Guido A; Mayer, Katharina A; Göschl, Lisa; Boucheron, Nicole; Ellmeier, Wilfried; Zlabinger, Gerhard J

    2016-11-01

    T cells must tightly regulate their metabolic processes to cope with varying bioenergetic demands depending on their state of differentiation. The metabolic sensor AMPK is activated in states of low energy supply and modulates cellular metabolism toward a catabolic state. Although this enzyme is known to be particularly active in regulatory T (Treg) cells, its impact on T helper (Th)-cell differentiation is poorly understood. We investigated the impact of several AMPK activators on Treg-cell differentiation and found that the direct activator AICAR (5-aminoimidazole-4-carboxamide ribonucleotide), but not the indirect activators metformin and 2-deoxyglucose, strongly enhanced Treg-cell induction by specifically enhancing Treg-cell expansion. Conversely, Th17 generation was impaired by the agent. Further investigation of the metabolic background of our observations revealed that AICAR enhanced both cellular mitochondrogenesis and fatty acid uptake. Consistently, increased Treg induction was entirely reversible on inhibition of fatty acid oxidation, thus confirming the dependence of AICAR's effects on metabolic pathways alterations. Translating our findings to an in vivo model, we found that the substance enhanced Treg cell generation on IL-2 complex-induced immune stimulation. We provide a previously unrecognized insight into the delicate interplay between immune cell function and metabolism and delineate a potential novel strategy for metabolism-targeting immunotherapy.-Gualdoni, G. A., Mayer, K. A., Göschl, L., Boucheron, N., Ellmeier, W., Zlabinger, G. J. The AMP analog AICAR modulates the Treg/Th17 axis through enhancement of fatty acid oxidation.

  1. Myeloid differentiation and retinoblastoma phosphorylation changes in HL-60 cells induced by retinoic acid receptor- and retinoid X receptor-selective retinoic acid analogs.

    Science.gov (United States)

    Brooks, S C; Kazmer, S; Levin, A A; Yen, A

    1996-01-01

    The ability of subtypes of retinoic acid receptors (RARs) and retinoid X receptors (RXRs) singly and in combination to elicit myeloid differentiation, G1/0-specific growth arrest, and retinoblastoma (RB) tumor suppressor protein dephosphorylation was determined in the human myeloblastic leukemia cell line HL-60 using subtype-selective retinoic acid (RA) analogs. RA analogs that selectively bind only to RARs (Am580 and/or TTNPB) or to RXRs (Ro 25-6603, SR11237, and/or SR11234) did not elicit the above-mentioned three cellular responses. In contrast, simultaneous treatment with both an RAR-selective ligand (Am580 or TTNPB) and an RXR-selective ligand (Ro 25-6603, SR11237, or SR11234) induced all three cellular processes. An RAR alpha-selective ligand used with an RXR-selective ligand generated the same responses as did all-trans RA or 9-cis RA, which affect both families of receptors, suggesting an important role for RAR alpha among RAR subtypes in eliciting cellular response. Consistent with this finding, the RAR alpha antagonist, Ro 41-5253, reduced the level of the cellular responses elicited by treatment with an RAR alpha-selective ligand plus RXR-selective ligand. The coupling of the shift of RB to its hypophosphorylated form with G1/0 arrest and differentiation in response to ligands is consistent with a possible role of RB as a downstream target or effector of RAR alpha and RXR in combination.

  2. Acid-Labile Amphiphilic PEO-b-PPO-b-PEO Copolymers: Degradable Poloxamer Analogs.

    Science.gov (United States)

    Worm, Matthias; Kang, Biao; Dingels, Carsten; Wurm, Frederik R; Frey, Holger

    2016-05-01

    Poly ((ethylene oxide)-b-(propylene oxide)-b-(ethylene oxide)) triblock copolymers commonly known as poloxamers or Pluronics constitute an important class of nonionic, biocompatible surfactants. Here, a method is reported to incorporate two acid-labile acetal moieties in the backbone of poloxamers to generate acid-cleavable nonionic surfactants. Poly(propylene oxide) is functionalized by means of an acetate-protected vinyl ether to introduce acetal units. Three cleavable PEO-PPO-PEO triblock copolymers (Mn,total = 6600, 8000, 9150 g·mol(-1) ; Mn,PEO = 2200, 3600, 4750 g·mol(-1) ) have been synthesized using anionic ring-opening polymerization. The amphiphilic copolymers exhibit narrow molecular weight distributions (Ð = 1.06-1.08). Surface tension measurements reveal surface-active behavior in aqueous solution comparable to established noncleavable poloxamers. Complete hydrolysis of the labile junctions after acidic treatment is verified by size exclusion chromatography. The block copolymers have been employed as surfactants in a miniemulsion polymerization to generate polystyrene (PS) nanoparticles with mean diameters of ≈200 nm and narrow size distribution, as determined by dynamic light scattering and scanning electron microscopy. Acid-triggered precipitation facilitates removal of surfactant fragments from the nanoparticles, which simplifies purification and enables nanoparticle precipitation "on demand."

  3. Generation of reactive oxygen species by a novel berberine–bile acid analog mediates apoptosis in hepatocarcinoma SMMC-7721 cells

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingyong, E-mail: li_qingyong@126.com [Key Laboratory of Forest Plant Ecology (Northeast Forestry University), Ministry of Education (China); Zhang, Li; Zu, Yuangang; Liu, Tianyu; Zhang, Baoyou; He, Wuna [Key Laboratory of Forest Plant Ecology (Northeast Forestry University), Ministry of Education (China)

    2013-04-19

    Graphical abstract: - Highlights: • Anticancer effects of B4, a novel berberine–bile acid analog, were tested. • B4 inhibited cell proliferation in hepatocellular carcinoma cells. • It also stimulated mitochondrial ROS production and membrane depolarization. • Effects of B4 were inhibited by a non-specific ROS scavenger. • Regulation of ROS generation may be a strategy for treating hepatic carcinoma. - Abstract: 2,3-Methenedioxy-9-O-(3′α,7′α-dihydroxy-5′β-cholan-24′-propy-lester) berberine (B4) is a novel berberine–bile acid analog synthesized in our laboratory. Previously, we showed that B4 exerted greater cytotoxicity than berberine in several human cancer cell lines. Therefore, we further evaluated the mechanism governing its anticancer actions in hepatocellular carcinoma SMMC-7721 cells. B4 inhibited the proliferation of SMMC-7721 cells, and stimulated reactive oxygen species (ROS) production and mitochondrial membrane depolarization; anti-oxidant capacity was reduced. B4 also induced the release of cytochrome c from the mitochondria to the cytosol and an increase in poly ADP-ribose polymerase (PARP) cleavage products, reflective of caspase-3 activation. Moreover, B4 induced the nuclear translocation of apoptosis-inducing factor (AIF) and a rise in DNA fragmentation. Pretreatment with the anti-oxidant N-acetylcysteine (NAC) inhibited B4-mediated effects, including cytotoxicity, ROS production, mitochondrial membrane depolarization increase in intracellular Ca{sup 2+}, cytochrome c release, PARP cleavage, and AIF translocation. Our data suggest that B4 induces ROS-triggered caspase-dependent and caspase-independent apoptosis pathways in SMMC-7721 cells and that ROS production may be a specific potential strategy for treating hepatic carcinoma.

  4. Radiolysis of Amino Acids in Outer Solar-System Ice Analogs

    Science.gov (United States)

    Gerakines, Perry A.; Hudson, Reggie L.

    2011-01-01

    Amino acids have been found in cometary dust particles and in the organic component of meteorites. These molecules, important for pre-biotic chemistry and for active biological systems, might be formed in cold planetary or interstellar environments and then delivered to H20-rich surfaces in the outer solar system. Many models for the availability of organic species on Earth and elsewhere depend on the ability of these molecules to survive in radiation-rich space environments. This poster presents results of O.8-MeV proton radiolysis of ice films at lS-140K. using infrared spectroscopy, the destruction rates of glycine, alanine, and phenylalanine have been determined for both pure films and those containing amino acids diluted in H2o. our results are discussed in terms of the survivability of these molecules in the icy surfaces present in the outer solar system and the possibility of their detection by instruments on board the New Horizons spacecraft

  5. Analog series-based scaffolds: computational design and exploration of a new type of molecular scaffolds for medicinal chemistry

    Science.gov (United States)

    Dimova, Dilyana; Stumpfe, Dagmar; Hu, Ye; Bajorath, Jürgen

    2016-01-01

    Aim: Computational design of and systematic search for a new type of molecular scaffolds termed analog series-based scaffolds. Materials & methods: From currently available bioactive compounds, analog series were systematically extracted, key compounds identified and new scaffolds isolated from them. Results: Using our computational approach, more than 12,000 scaffolds were extracted from bioactive compounds. Conclusion: A new scaffold definition is introduced and a computational methodology developed to systematically identify such scaffolds, yielding a large freely available scaffold knowledge base.

  6. Analog series-based scaffolds: computational design and exploration of a new type of molecular scaffolds for medicinal chemistry.

    Science.gov (United States)

    Dimova, Dilyana; Stumpfe, Dagmar; Hu, Ye; Bajorath, Jürgen

    2016-12-01

    Computational design of and systematic search for a new type of molecular scaffolds termed analog series-based scaffolds. From currently available bioactive compounds, analog series were systematically extracted, key compounds identified and new scaffolds isolated from them. Using our computational approach, more than 12,000 scaffolds were extracted from bioactive compounds. A new scaffold definition is introduced and a computational methodology developed to systematically identify such scaffolds, yielding a large freely available scaffold knowledge base.

  7. An analog integrated signal processing circuit for on-chip diffusion-based gas analysis

    Science.gov (United States)

    Sadeghi, Hesam; Ghafarinia, Vahid

    2013-07-01

    In diffusion-based gas analysis, the transient of gas diffusion process is recorded by a generic gas sensor to serve as a fingerprint for qualitative and quantitative analysis of gaseous samples. Following the acquisition of these specific signals, any standalone gas analyzer requires a pattern recognition system for pattern classification. The classic digital pattern recognition methods require computing hardware of adequate computational throughput. In this paper, we have followed a straightforward mathematical procedure to relate the signals to their associated target gases. We have shown that the procedure can be implemented by a set of analog functions. Based on the results, we have designed an analog integrated circuit, in 0.18 µm standard CMOS process, for processing the diffusion-based transient signals. The main circuit components are a low-pass filter, the differentiator, the feature extractor and an artificial neural network. The output of the circuit is a 2-bit binary code that specifies the target gas. The circuit successfully classified four alcoholic vapors by processing the experimentally obtained response patterns. The proposed signal processing circuit, the semiconductor gas sensor and the diffusion channel can all be implemented on a single substrate to fabricate an integrated micro gas analyzer.

  8. Effective low-power wearable wireless surface EMG sensor design based on analog-compressed sensing.

    Science.gov (United States)

    Balouchestani, Mohammadreza; Krishnan, Sridhar

    2014-12-17

    Surface Electromyography (sEMG) is a non-invasive measurement process that does not involve tools and instruments to break the skin or physically enter the body to investigate and evaluate the muscular activities produced by skeletal muscles. The main drawbacks of existing sEMG systems are: (1) they are not able to provide real-time monitoring; (2) they suffer from long processing time and low speed; (3) they are not effective for wireless healthcare systems because they consume huge power. In this work, we present an analog-based Compressed Sensing (CS) architecture, which consists of three novel algorithms for design and implementation of wearable wireless sEMG bio-sensor. At the transmitter side, two new algorithms are presented in order to apply the analog-CS theory before Analog to Digital Converter (ADC). At the receiver side, a robust reconstruction algorithm based on a combination of ℓ1-ℓ1-optimization and Block Sparse Bayesian Learning (BSBL) framework is presented to reconstruct the original bio-signals from the compressed bio-signals. The proposed architecture allows reducing the sampling rate to 25% of Nyquist Rate (NR). In addition, the proposed architecture reduces the power consumption to 40%, Percentage Residual Difference (PRD) to 24%, Root Mean Squared Error (RMSE) to 2%, and the computation time from 22 s to 9.01 s, which provide good background for establishing wearable wireless healthcare systems. The proposed architecture achieves robust performance in low Signal-to-Noise Ratio (SNR) for the reconstruction process.

  9. Effective Low-Power Wearable Wireless Surface EMG Sensor Design Based on Analog-Compressed Sensing

    Directory of Open Access Journals (Sweden)

    Mohammadreza Balouchestani

    2014-12-01

    Full Text Available Surface Electromyography (sEMG is a non-invasive measurement process that does not involve tools and instruments to break the skin or physically enter the body to investigate and evaluate the muscular activities produced by skeletal muscles. The main drawbacks of existing sEMG systems are: (1 they are not able to provide real-time monitoring; (2 they suffer from long processing time and low speed; (3 they are not effective for wireless healthcare systems because they consume huge power. In this work, we present an analog-based Compressed Sensing (CS architecture, which consists of three novel algorithms for design and implementation of wearable wireless sEMG bio-sensor. At the transmitter side, two new algorithms are presented in order to apply the analog-CS theory before Analog to Digital Converter (ADC. At the receiver side, a robust reconstruction algorithm based on a combination of ℓ1-ℓ1-optimization and Block Sparse Bayesian Learning (BSBL framework is presented to reconstruct the original bio-signals from the compressed bio-signals. The proposed architecture allows reducing the sampling rate to 25% of Nyquist Rate (NR. In addition, the proposed architecture reduces the power consumption to 40%, Percentage Residual Difference (PRD to 24%, Root Mean Squared Error (RMSE to 2%, and the computation time from 22 s to 9.01 s, which provide good background for establishing wearable wireless healthcare systems. The proposed architecture achieves robust performance in low Signal-to-Noise Ratio (SNR for the reconstruction process.

  10. Effective Low-Power Wearable Wireless Surface EMG Sensor Design Based on Analog-Compressed Sensing

    Science.gov (United States)

    Balouchestani, Mohammadreza; Krishnan, Sridhar

    2014-01-01

    Surface Electromyography (sEMG) is a non-invasive measurement process that does not involve tools and instruments to break the skin or physically enter the body to investigate and evaluate the muscular activities produced by skeletal muscles. The main drawbacks of existing sEMG systems are: (1) they are not able to provide real-time monitoring; (2) they suffer from long processing time and low speed; (3) they are not effective for wireless healthcare systems because they consume huge power. In this work, we present an analog-based Compressed Sensing (CS) architecture, which consists of three novel algorithms for design and implementation of wearable wireless sEMG bio-sensor. At the transmitter side, two new algorithms are presented in order to apply the analog-CS theory before Analog to Digital Converter (ADC). At the receiver side, a robust reconstruction algorithm based on a combination of ℓ1-ℓ1-optimization and Block Sparse Bayesian Learning (BSBL) framework is presented to reconstruct the original bio-signals from the compressed bio-signals. The proposed architecture allows reducing the sampling rate to 25% of Nyquist Rate (NR). In addition, the proposed architecture reduces the power consumption to 40%, Percentage Residual Difference (PRD) to 24%, Root Mean Squared Error (RMSE) to 2%, and the computation time from 22 s to 9.01 s, which provide good background for establishing wearable wireless healthcare systems. The proposed architecture achieves robust performance in low Signal-to-Noise Ratio (SNR) for the reconstruction process. PMID:25526357

  11. Reaction of trifluoroacetaldehyde with amino acids, nucleotides, lipid nucleophiles, and their analogs.

    Science.gov (United States)

    Yin, H; Crowder, R J; Jones, J P; Anders, M W

    1996-01-01

    Trihaloacetaldehydes are used as sedatives, are key intermediates in the metabolism of 1,1,1,2-tetrahaloethanes, some of which are chlorofluorocarbon substitutes, and are metabolites of trihaloethanols, which are intestinal and bone marrow toxins. In the present study, trifluoroacetaldehyde was used as a model to examine the reactions of trihaloacetaldehydes with cellular nucleophiles, including amino acids, nucleotides, and lipid components. Reaction of trifluoroacetaldehyde hydrate (10 mM) with amino acids (100 mM) in buffer at pH 7.0 and 30 degrees C showed that only L-cysteine formed stable adducts, which were identified as (2R,4R)- and (2S,4R)-2-(trifluoromethyl)thiazolidine-4-carboxylic acid. The absolute stereochemistry of (2R,4R)- and (2S,4R)-2-(trifluoromethyl)thiazolidine-4-carboxylic acid was determined by homonuclear Overhauser effect experiments. The diastereoisomers were formed in a 2.8:1 ratio at 37 degrees C and in a 1:4.0 ratio at 80 degrees C. Trifluoroacetaldehyde also reacted with L-cysteine methyl ester and 2-mercaptoethylamine to form stable thiazolidine derivatives, but did not react with N-acetyl-L-cysteine. The reaction of trifluoroacetaldehyde with the amino groups of ATP, GMP, CMP, L-citrulline, and urea resulted in the formation of stable imines. TMP, which lacks an exocyclic amino group, did not react. Glutathione reacted with trifluoroacetaldehyde to form (2R,5R)- and (2S,5R)-5-amino-6-[carboxymethyl)imino]-2-(trifluoromethyl)-1,3- oxathiane, whose formation was accompanied by simultaneous cleavage of the glutamyl moiety. The reactivity of nucleophilic groups with trifluoroacetaldehyde follows the order SH > NH2 > OH. The results of the present study indicate that trifluoroacetaldehyde covalently modifies cellular nucleophiles. The biological significance of these reactions warrants further investigation. The reaction of trifluoroacetaldehyde with L-cysteine and glutathione may afford routes for the stereoselective synthesis of

  12. Synthesis, molecular modeling and biological evaluation of two new chicoric acid analogs.

    Science.gov (United States)

    Righi, Giuliana; Pelagalli, Romina; Isoni, Valerio; Tirotta, Ilaria; Dallocchio, Roberto; Dessì, Alessandro; Macchi, Beatrice; Frezza, Caterina; Rossetti, Ilaria; Bovicelli, Paolo

    2017-02-01

    Two conformationally constrained compounds similar to chicoric acid but lacking the catechol and carboxyl groups were prepared. In these analogues, the single bond between the two caffeoyl fragments has been replaced with a chiral oxirane ring and both aromatic residues modified protecting completely or partially the catechol moiety as methyl ether. Preliminary molecular modelling studies carried out on the two analogues showed interactions near the active site of HIV integrase; however, in comparison with raltegravir, the biological evaluation confirmed that CAA-1 and CAA-2 were unable to inhibit infection at lower concentration.

  13. Reactive Distillation for Esterification of Bio-based Organic Acids

    Energy Technology Data Exchange (ETDEWEB)

    Fields, Nathan; Miller, Dennis J.; Asthana, Navinchandra S.; Kolah, Aspi K.; Vu, Dung; Lira, Carl T.

    2008-09-23

    The following is the final report of the three year research program to convert organic acids to their ethyl esters using reactive distillation. This report details the complete technical activities of research completed at Michigan State University for the period of October 1, 2003 to September 30, 2006, covering both reactive distillation research and development and the underlying thermodynamic and kinetic data required for successful and rigorous design of reactive distillation esterification processes. Specifically, this project has led to the development of economical, technically viable processes for ethyl lactate, triethyl citrate and diethyl succinate production, and on a larger scale has added to the overall body of knowledge on applying fermentation based organic acids as platform chemicals in the emerging biorefinery. Organic acid esters constitute an attractive class of biorenewable chemicals that are made from corn or other renewable biomass carbohydrate feedstocks and replace analogous petroleum-based compounds, thus lessening U.S. dependence on foreign petroleum and enhancing overall biorefinery viability through production of value-added chemicals in parallel with biofuels production. Further, many of these ester products are candidates for fuel (particularly biodiesel) components, and thus will serve dual roles as both industrial chemicals and fuel enhancers in the emerging bioeconomy. The technical report from MSU is organized around the ethyl esters of four important biorenewables-based acids: lactic acid, citric acid, succinic acid, and propionic acid. Literature background on esterification and reactive distillation has been provided in Section One. Work on lactic acid is covered in Sections Two through Five, citric acid esterification in Sections Six and Seven, succinic acid in Section Eight, and propionic acid in Section Nine. Section Ten covers modeling of ester and organic acid vapor pressure properties using the SPEAD (Step Potential

  14. The Effects of Analogies and Mathematics Ability on Students' Programming Learning Using Computer-Based Learning.

    Science.gov (United States)

    Lai, Shu-Ling; Repman, Judith L.

    1996-01-01

    Purposes of this study were to determine: (1) if analogies and elaboration and placement of the analogies help novices learning a computer-programming language; (2) if students' mathematics ability influences programming learning; and (3) the interaction effects between analogy and mathematics ability. Subjects were 156 college students. Results…

  15. A New Automated Design Method Based on Machine Learning for CMOS Analog Circuits

    Science.gov (United States)

    Moradi, Behzad; Mirzaei, Abdolreza

    2016-11-01

    A new simulation based automated CMOS analog circuit design method which applies a multi-objective non-Darwinian-type evolutionary algorithm based on Learnable Evolution Model (LEM) is proposed in this article. The multi-objective property of this automated design of CMOS analog circuits is governed by a modified Strength Pareto Evolutionary Algorithm (SPEA) incorporated in the LEM algorithm presented here. LEM includes a machine learning method such as the decision trees that makes a distinction between high- and low-fitness areas in the design space. The learning process can detect the right directions of the evolution and lead to high steps in the evolution of the individuals. The learning phase shortens the evolution process and makes remarkable reduction in the number of individual evaluations. The expert designer's knowledge on circuit is applied in the design process in order to reduce the design space as well as the design time. The circuit evaluation is made by HSPICE simulator. In order to improve the design accuracy, bsim3v3 CMOS transistor model is adopted in this proposed design method. This proposed design method is tested on three different operational amplifier circuits. The performance of this proposed design method is verified by comparing it with the evolutionary strategy algorithm and other similar methods.

  16. Design of Multi-Valued Quaternary Based Analog-to-Digital Converter

    Directory of Open Access Journals (Sweden)

    A. H.M.Z. Alam

    2009-01-01

    Full Text Available Problem statement: The design of multi-valued quaternary based Analog-to-Digital Converter (ADC circuit was presented. The ADC generates multi-valued logic outputs rather than the conventional binary output system to overall reduction in circuit complexity and size. Approach: Design was implemented using pipeline ADC architecture and was simulated using model parameters based on standard 0.13 µm CMOS process. Results: Performance analysis of the design showed desirable performance parameters in terms of response, low power consumption, and a sampling rate of 10 MHz at a supply voltage of 1.3V was achieved. Conclusion/Recommendations: The ADC design was suitable for the needs of mixed-signal integrated circuit design and can be implemented as a conversion circuit for systems based on multiple-valued logic design.

  17. Structured Analog CMOS Design

    CERN Document Server

    Stefanovic, Danica

    2008-01-01

    Structured Analog CMOS Design describes a structured analog design approach that makes it possible to simplify complex analog design problems and develop a design strategy that can be used for the design of large number of analog cells. It intentionally avoids treating the analog design as a mathematical problem, developing a design procedure based on the understanding of device physics and approximations that give insight into parameter interdependences. The proposed transistor-level design procedure is based on the EKV modeling approach and relies on the device inversion level as a fundament

  18. Nucleic acid based logical systems.

    Science.gov (United States)

    Han, Da; Kang, Huaizhi; Zhang, Tao; Wu, Cuichen; Zhou, Cuisong; You, Mingxu; Chen, Zhuo; Zhang, Xiaobing; Tan, Weihong

    2014-05-12

    Researchers increasingly visualize a significant role for artificial biochemical logical systems in biological engineering, much like digital logic circuits in electrical engineering. Those logical systems could be utilized as a type of servomechanism to control nanodevices in vitro, monitor chemical reactions in situ, or regulate gene expression in vivo. Nucleic acids (NA), as carriers of genetic information with well-regulated and predictable structures, are promising materials for the design and engineering of biochemical circuits. A number of logical devices based on nucleic acids (NA) have been designed to handle various processes for technological or biotechnological purposes. This article focuses on the most recent and important developments in NA-based logical devices and their evolution from in vitro, through cellular, even towards in vivo biological applications.

  19. Novel CCII-based Field Programmable Analog Array and its Application to a Sixth-Order Butterworth LPF

    OpenAIRE

    S. A. Mahmoud; Soliman, E. A.

    2013-01-01

    In this paper, a field programmable analog array (FPAA) is proposed. The proposed FPAA consists of seven configurable analog blocks (CABs) arranged in a hexagonal lattice such that the CABs are directly connected to each other. This structure improves the overall frequency response of the chip by decreasing the parasitic capacitances in the signal path. The CABS of the FPAA is based on a novel fully differential digitally programmable current conveyor (DPCCII). The programmability of the DPCC...

  20. Modulation of DNA methylation and gene expression in cultured sycamore cells treated by hypomethylating base analog.

    Science.gov (United States)

    Ngernprasirtsiri, J; Akazawa, T

    1990-12-12

    The selective suppression of photosynthetic genes in both the nuclear and plastid genomes of the nonphotosynthetic white wild-type cell line of sycamore (Acer pseudoplatanus) has been found to be inversely related to the presence of a variety of methylated bases, especially 5-methylcytosine (5-MeCyt) and N6-methyladenine (N6-MeAde), localized in regions of the plastid genome containing silent genes. We used hypomethylating base analogs to manipulate the level of cytosine and adenine methylation in the white cells of sycamore, and examined the effects of changes in methylation on gene expression. Treatment with 5-azacytidine (5-AzaCyd) and N6-benzyladenine (N6-BzlAde) decreased cytosine and adenine methylation. This was accompanied by restoration of transcriptional activity in photosynthetic genes which are usually suppressed. Both 5-MeCyt and N6-MeAde suppressed nuclear gene expression, but only 5-MeCyt suppressed plastid gene expression.

  1. Multisensor transducer based on a parallel fiber optic digital-to-analog converter

    Directory of Open Access Journals (Sweden)

    Grechishnikov Vladimir

    2017-01-01

    Full Text Available Considered possibility of creating a multisensory information converter (MSPI based on new fiber-optic functional element-digital-to-analog (DAC fiber optic converter. The use of DAC fiber-optic provides jamming immunity combined with low weight and cost of indicators .Because of that MSPI scheme was developed based on parallel DAC fiber-optic (Russian Federation Patent 157416. We came up with an equation for parallel DAC fiber-optic. An eleborate general mathematical model of the proposed converter. Developed a method for reducing conversion errors by placing the DAC transfer function between i and i + 1 ADC quantization levels. By using this model it allows you to obtain reliable information about the technical capabilities of a converter without the need for costly experiments.

  2. Noise-shaping gradient descent-based online adaptation algorithms for digital calibration of analog circuits.

    Science.gov (United States)

    Chakrabartty, Shantanu; Shaga, Ravi K; Aono, Kenji

    2013-04-01

    Analog circuits that are calibrated using digital-to-analog converters (DACs) use a digital signal processor-based algorithm for real-time adaptation and programming of system parameters. In this paper, we first show that this conventional framework for adaptation yields suboptimal calibration properties because of artifacts introduced by quantization noise. We then propose a novel online stochastic optimization algorithm called noise-shaping or ΣΔ gradient descent, which can shape the quantization noise out of the frequency regions spanning the parameter adaptation trajectories. As a result, the proposed algorithms demonstrate superior parameter search properties compared to floating-point gradient methods and better convergence properties than conventional quantized gradient-methods. In the second part of this paper, we apply the ΣΔ gradient descent algorithm to two examples of real-time digital calibration: 1) balancing and tracking of bias currents, and 2) frequency calibration of a band-pass Gm-C biquad filter biased in weak inversion. For each of these examples, the circuits have been prototyped in a 0.5-μm complementary metal-oxide-semiconductor process, and we demonstrate that the proposed algorithm is able to find the optimal solution even in the presence of spurious local minima, which are introduced by the nonlinear and non-monotonic response of calibration DACs.

  3. Is neoclassical microeconomics formally valid? An approach based on an analogy with equilibrium thermodynamics

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, Tania; Domingos, Tiago [Environment and Energy Section, DEM, Instituto Superior Tecnico, Avenida Rovisco Pais, 1, 1049-001 Lisboa (Portugal)

    2006-06-10

    The relation between Thermodynamics and Economics is a paramount issue in Ecological Economics. Two different levels can be distinguished when discussing it: formal and substantive. At the formal level, a mathematical framework is used to describe both thermodynamic and economic systems. At the substantive level, thermodynamic laws are applied to economic processes. In Ecological Economics, there is a widespread claim that neoclassical economics has the same mathematical formulation as classical mechanics and is therefore fundamentally flawed because: (1) utility does not obey a conservation law as energy does; (2) an equilibrium theory cannot be used to study irreversible processes. Here, we show that neoclassical economics is based on a wrong formulation of classical mechanics, being in fact formally analogous to equilibrium thermodynamics. The similarity between both formalisms, namely that they are both cases of constrained optimisation, is easily perceived when thermodynamics is looked upon using the Tisza-Callen axiomatisation. In this paper, we take the formal analogy between equilibrium thermodynamics and economic systems far enough to answer the formal criticisms, proving that the formalism of neoclassical economics has irreversibility embedded in it. However, the formal similarity between equilibrium thermodynamics and neoclassical microeconomics does not mean that economic models are in accordance with mass, energy and entropy balance equations. In fact, neoclassical theory suffers from flaws in the substantive integration with thermodynamic laws as has already been fully demonstrated by valuable work done by ecological economists in this field. (author)

  4. Small Molecule AngIV-based Analogs to Treat Alzheimers Disease

    Directory of Open Access Journals (Sweden)

    John W Wright

    2016-06-01

    Full Text Available Alzheimer’s disease (AD patients are presently without adequate treatment thus new therapeutic approaches are needed to slow and hopefully reverse disease progression. Neurotrophic agents such as nerve growth factor and brain-derived neurotrophic factor have received research attention concerning their potential to treat AD but have not progressed to clinical trials due to their large size, inability to penetrate the blood-brain barrier (BBB, and the high cost of synthesis. This review focuses on one over looked neurotrophin, hepatocyte growth factor (HGF that acts via the Type 1 tyrosine kinase receptor Met to mediate stem cell differentiation, synaptogenesis, neurogenesis, and protect against tissue insults in a wide range of cell types including neurons. We have determined that the brain angiotensin and HGF/c-Met systems interact in such a way that angiotensin IV (AngIV-based analogs including Nle1-AngIV, Norleual-AngIV, Dihexa, and others influence HGF dimerization which is a prerequisite to binding at the Met receptor. Several of these analogs have shown the ability to facilitate the formation of new functional synaptic connections in hippocampal slices, promote neurogenesis, and augment memory consolidation and retrieval in animal models of AD. This family of compounds represents a new class of drugs with lead candidates that are orally active, penetrate the BBB sufficiently to reach therapeutic concentrations, and reverse memory deficits seen in animal models of dementia.

  5. Synthesis and structure-activity relationship of p-carborane-based non-secosteroidal vitamin D analogs.

    Science.gov (United States)

    Fujii, Shinya; Kano, Atsushi; Songkram, Chalermkiat; Masuno, Hiroyuki; Taoda, Yoshiyuki; Kawachi, Emiko; Hirano, Tomoya; Tanatani, Aya; Kagechika, Hiroyuki

    2014-02-15

    1α,25-Dihydroxyvitamin D3 [1α,25(OH)₂D₃: 1] is a specific modulator of nuclear vitamin D receptor (VDR), and novel vitamin D analogs are therapeutic candidates for multiple clinical applications. We recently developed non-secosteroidal VDR agonists bearing a p-carborane cage (a carbon-containing boron cluster) as a hydrophobic core structure. These carborane derivatives are structurally quite different from classical secosteroidal vitamin D analogs. Here, we report systematic synthesis and activity evaluation of carborane-based non-secosteroidal vitamin D analogs. The structure-activity relationships of carborane derivatives are different from those of secosteroidal vitamin D derivatives, and in particular, the length and the substituent position of the dihydroxylated side chain are rather flexible in carborane derivatives. The structure-activity relationships presented here should be helpful in development of non-secosteroidal vitamin D analogs for clinical applications.

  6. Medicinally Used Asarum Species: High-Resolution LC-MS Analysis of Aristolochic Acid Analogs and In vitro Toxicity Screening in HK-2 Cells

    Directory of Open Access Journals (Sweden)

    Johanna Michl

    2017-05-01

    Full Text Available Species of Asarum are used in traditional Chinese medicine and, similar to members of the genus Aristolochia, they contain aristolochic acid analogs (AAAs. These compounds are known for their nephrotoxic and carcinogenic effects. So far, the phytochemistry and nephrotoxicity of species of Asarum is not well studied. A high-resolution LC-MS-based metabolomic approach was used to study the phytochemical variation in medicinally used Asarum species. The cytotoxicity of the samples was assessed using human kidney (HK-2 cells. The majority of samples contained potentially nephrotoxic AAAs, including 9-methoxy aristolactam (AL IV, AL I, and AL IV. These compounds were present in methanol as well as water extracts. AAAs were detected in all parts of the plant. The majority of the extracts were not cytotoxic to HK-2 cells at the doses tested. However, other mechanisms relating to aristolochic acid nephropathy and cancer development, such as DNA adduct formation may occur. The results of this study provide a model for assessing lesser-known plant species for toxicity.

  7. Determination of an organic-acid analog of DOC for use in copper toxicity studies on salmonids

    Energy Technology Data Exchange (ETDEWEB)

    MacRae, R.K.; Meyer, J.S.; Hansen, J.A.; Bergman, H.L. [Univ. of Wyoming, Laramie, WY (United States); Maest, A.; Marr, J.; Beltman, D.; Lipton, J. [Hagler Bailly, Inc., Boulder, CO (United States)

    1995-12-31

    Concentrations of dissolved copper in streams draining mine sites often exceed concentrations shown to cause acute and chronic mortality in salmonids. However, toxicity and impaired behaviors may be modified by dissolved organic carbon (DOC) and other inorganic components present in the site water. The effects of DOC on copper speciation, and thus bioavailability and toxicity, were determined by titrating stream waters with copper, using a cupric ion-specific electrode to detect free copper concentrations. Effects of various competing cations (e.g., Ca{sup +2}, Co{sup +2}) on copper-DOC binding were also evaluated. Titration results were evaluated using Scatchard and non-linear regression analyses to quantify the strength and capacity of copper-DOC binding. Inorganic speciation was determined using the geochemical model MINEQL{sup +}. Results of these titrations indicated the presence of two or three distinct copper binding components in site water DOC. Three commercially available organic acids where then chosen to mimic the binding characteristics of natural DOC. This DOC-analog was used successfully in fish toxicity studies to evaluate the influence of DOC on copper bioavailability. Geochemical models were developed to predict copper speciation in both laboratory test waters and site waters, for any typical combination of water chemistry parameters (pH, alkalinity, [DOC], etc.). A combined interpretation of fish toxicity and modeling results indicate that some DOC-bound copper was bioavailable.

  8. Influence of Iron on Production of the Antibacterial Compound Tropodithietic Acid and Its Noninhibitory Analog in Phaeobacter inhibens.

    Science.gov (United States)

    D'Alvise, Paul W; Phippen, Christopher B W; Nielsen, Kristian F; Gram, Lone

    2015-10-30

    Tropodithietic acid (TDA) is an antibacterial compound produced by some Phaeobacter and Ruegeria spp. of the Roseobacter clade. TDA production is studied in marine broth or agar since antibacterial activity in other media is not observed. The purpose of this study was to determine how TDA production is influenced by substrate components. High concentrations of ferric citrate, as present in marine broth, or other iron sources were required for production of antibacterially active TDA. However, when supernatants of noninhibitory, low-iron cultures of Phaeobacter inhibens were acidified, antibacterial activity was detected in a bioassay. The absence of TDA in nonacidified cultures and the presence of TDA in acidified cultures were verified by liquid chromatography-high-resolution mass spectrometry. A noninhibitory TDA analog (pre-TDA) was produced by P. inhibens, Ruegeria mobilis F1926, and Phaeobacter sp. strain 27-4 under low-iron concentrations and was instantaneously converted to TDA when pH was lowered. Production of TDA in the presence of Fe(3+) coincides with formation of a dark brown substance, which could be precipitated by acid addition. From this brown pigment TDA could be liberated slowly with aqueous ammonia, and both direct-infusion mass spectrometry and elemental analysis indicated a [Fe(III)(TDA)2]x complex. The pigment could also be produced by precipitation of pure TDA with FeCl3. Our results raise questions about how biologically active TDA is produced in natural marine settings where iron is typically limited and whether the affinity of TDA to iron points to a physiological or ecological function of TDA other than as an antibacterial compound. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  9. The synthesis and characterization of analogs of the antimicrobial compound squalamine: 6 beta-hydroxy-3-aminosterols synthesized from hyodeoxycholic acid.

    Science.gov (United States)

    Jones, S R; Kinney, W A; Zhang, X; Jones, L M; Selinsky, B S

    1996-10-01

    Analogs of the aminosterol antimicrobial agent squalamine have been synthesized beginning from hyodeoxycholic acid. After carboxylic acid esterification and oxidation of both alcohol functions to ketones, the A/B ring junction was converted from cis to trans by acid-catalyzed isomerization. Different polyamines were added to the 3-keto group by reductive amination, yielding both the 3 alpha and 3 beta addition products. The synthetic products exhibited potent, broad-spectrum antimicrobial activity similar to that of the parent compound. Changing the identity of the polyamine or the stereochemistry of addition has little effect upon antimicrobial activity but appears to change the selectivity of the agents. The analogs are synthesized with high yield from inexpensive starting materials and are promising alternatives to squalamine as potential antibiotics.

  10. A dynamic CMOS multiplier for analog VLSI based on exponential pulse-decay modulation

    Science.gov (United States)

    Massengill, Lloyd W.

    1991-03-01

    A clocked, charge-based, CMOS modulator circuit is presented. The circuit, which performs a semilinear multiplication function, has applications in arrayed analog VLSI architectures such as parallel filters and neural network systems. The design presented is simple in structure, uses no operational amplifiers for the actual multiplication function, and uses no power in the static mode. Two-quadrant weighting of an input signal is accomplished by control of the magnitude and decay time of an exponential current pulse, resulting in the delivery of charge packets to a shared capacitive summing bus. The cell is modular in structure and can be fabricated in a standard CMOS process. An analytical derivation of the operation of the circuit, SPICE simulations, and MOSIS fabrication results are presented. The simulation studies indicate that the circuit is inherently tolerant to temperature effects, absolute device sizing errors, and clock-feedthrough transients.

  11. Photonic Beamformer Model Based on Analog Fiber-Optic Links’ Components

    Science.gov (United States)

    Volkov, V. A.; Gordeev, D. A.; Ivanov, S. I.; Lavrov, A. P.; Saenko, I. I.

    2016-08-01

    The model of photonic beamformer for wideband microwave phased array antenna is investigated. The main features of the photonic beamformer model based on true-time-delay technique, DWDM technology and fiber chromatic dispersion are briefly analyzed. The performance characteristics of the key components of photonic beamformer for phased array antenna in the receive mode are examined. The beamformer model composed of the components available on the market of fiber-optic analog communication links is designed and tentatively investigated. Experimental demonstration of the designed model beamforming features includes actual measurement of 5-element microwave linear array antenna far-field patterns in 6-16 GHz frequency range for antenna pattern steering up to 40°. The results of experimental testing show good accordance with the calculation estimates.

  12. Autonomous, Computer-Based Behavioral Health Countermeasure Evaluation at HI-SEAS Mars Analog.

    Science.gov (United States)

    Anderson, Allison P; Fellows, Abigail M; Binsted, Kim A; Hegel, Mark T; Buckey, Jay C

    Living in an isolated, confined environment (ICE) can induce conflict, stress, and depression. Computer-based behavioral health countermeasures are appealing for training and treatment in ICEs because they provide confidentiality and do not require communication with the outside environment. We evaluated the Virtual Space Station (VSS), a suite of interactive computer-delivered psychological training and treatment programs, at the Hawaii Space Exploration Analog and Simulation (HI-SEAS) III expedition. Six subjects (3 male, 3 female) spent 8 mo in group-isolation and used the Conflict, Stress, and Depression modules in the VSS. Survey evaluations, data collected within the program, and postdeployment interviews were collected. This crew dealt with behavioral health issues common to ICEs. The VSS proved to be a valuable resource and was used both as intended, and in unanticipated ways, to help maintain behavioral health. The Conflict and Stress Modules were rated as highly acceptable (1.8 on a 7-point Likert scale). The crew identified a total of 13 stressors and worked on 9 problems through the VSS. Opinions about the modules were highly individualized. Crewmembers identified exercises in the VSS that were applicable and not applicable to their needs. Additional content to improve the program was identified. Autonomous, confidential training and treatment for behavioral health issues will need to be a critical component of long duration spaceflight travel. This work provides an evaluation of such a tool in a relevant ICE. Anderson AP, Fellows AM, Binsted KA, Hegel MT, Buckey JC. Autonomous, computer-based behavioral health countermeasure evaluation at HI-SEAS Mars analog. Aerosp Med Hum Perform. 2016; 87(11):912-920.

  13. Stereoselective synthesis of nicotinamide beta-riboside and nucleoside analogs.

    Science.gov (United States)

    Franchetti, Palmarisa; Pasqualini, Michela; Petrelli, Riccardo; Ricciutelli, Massimo; Vita, Patrizia; Cappellacci, Loredana

    2004-09-20

    The beta-anomers of N-ribofuranosylnicotine-3-carboxamide (beta-NAR) and its nicotinic acid analog (beta-NaR) were obtained by stereoselective synthesis via glycosylation of the presilylated bases under Vorbruggen's protocol. A NAR analog, methylated in position 3 of the ribosylic moiety, is also reported.

  14. The Acid-Base Titration of a Very Weak Acid: Boric Acid

    Science.gov (United States)

    Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

    2012-01-01

    A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

  15. The Acid-Base Titration of a Very Weak Acid: Boric Acid

    Science.gov (United States)

    Celeste, M.; Azevedo, C.; Cavaleiro, Ana M. V.

    2012-01-01

    A laboratory experiment based on the titration of boric acid with strong base in the presence of d-mannitol is described. Boric acid is a very weak acid and direct titration with NaOH is not possible. An auxiliary reagent that contributes to the release of protons in a known stoichiometry facilitates the acid-base titration. Students obtain the…

  16. Modular Hybrid Energy Concept Employing a Novel Control Structure Based on a Simple Analog System

    Directory of Open Access Journals (Sweden)

    PETREUS, D.

    2016-05-01

    Full Text Available This paper proposes a novel control topology which enables the setup of a low cost analog system leading to the implementation of a modular energy conversion system. The modular concept is based on hybrid renewable energy (solar and wind and uses high voltage inverters already available on the market. An important feature of the proposed topology is a permanently active current loop, which assures short circuit protection and simplifies the control loops compensation. The innovative analogue solution of the control structure is based on a dedicated integrated circuit (IC for power factor correction (PFC circuits, used in a new configuration, to assure an efficient inverter start-up. The energy conversion system (control structure and maximum power point tracking algorithm is simulated using a new macromodel-based concept, which reduces the usual computational burden of the simulator and achieves high processing speed. The proposed novel system is presented in this article from concept, through the design and implementation stages, is verified through simulation and is validated by experimental results.

  17. Analog optical computing based on a dielectric meta-reflect array.

    Science.gov (United States)

    Chizari, Ata; Abdollahramezani, Sajjad; Jamali, Mohammad Vahid; Salehi, Jawad A

    2016-08-01

    In this Letter, we realize the concept of analog computing using an engineered gradient dielectric meta-reflect-array. The proposed configuration consists of individual subwavelength silicon nanobricks, in combination with a fused silica spacer and silver ground plane, realizing a reflection beam with full phase coverage of 2π degrees, as well as an amplitude range of 0 to 1. Spectrally overlapping electric and magnetic dipole resonances, such high-index dielectric metasurfaces can locally and independently manipulate the amplitude and phase of the incident electromagnetic wave. This practically feasible structure overcomes substantial limitations imposed by plasmonic metasurfaces such as absorption losses and low polarization conversion efficiency in the visible range. Using such CMOS-compatible and easily integrable platforms promises highly efficient ultrathin planar wave-based computing systems that circumvent the drawbacks of conventional bulky lens-based signal processors. Based on these key properties and the general concept of spatial Fourier transformation, we design and realize broadband mathematical operators such as the differentiator and integrator in the telecommunication wavelengths.

  18. Non-racemic Amino Acid Production by Ultraviolet Irradiation of Achiral Interstellar Ice Analogs with Circularly Polarized Light

    Science.gov (United States)

    de Marcellus, Pierre; Meinert, Cornelia; Nuevo, Michel; Filippi, Jean-Jacques; Danger, Grégoire; Deboffle, Dominique; Nahon, Laurent; Le Sergeant d'Hendecourt, Louis; Meierhenrich, Uwe J.

    2011-02-01

    The delivery of organic matter to the primitive Earth via comets and meteorites has long been hypothesized to be an important source for prebiotic compounds such as amino acids or their chemical precursors that contributed to the development of prebiotic chemistry leading, on Earth, to the emergence of life. Photochemistry of inter/circumstellar ices around protostellar objects is a potential process leading to complex organic species, although difficult to establish from limited infrared observations only. Here we report the first abiotic cosmic ice simulation experiments that produce species with enantiomeric excesses (e.e.'s). Circularly polarized ultraviolet light (UV-CPL) from a synchrotron source induces asymmetric photochemistry on initially achiral inter/circumstellar ice analogs. Enantioselective multidimensional gas chromatography measurements show significant e.e.'s of up to 1.34% for (13C)-alanine, for which the signs and absolute values are related to the helicity and number of CPL photons per deposited molecule. This result, directly comparable with some L excesses measured in meteorites, supports a scenario in which exogenous delivery of organics displaying a slight L excess, produced in an extraterrestrial environment by an asymmetric astrophysical process, is at the origin of biomolecular asymmetry on Earth. As a consequence, a fraction of the meteoritic organic material consisting of non-racemic compounds may well have been formed outside the solar system. Finally, following this hypothesis, we support the idea that the protosolar nebula has indeed been formed in a region of massive star formation, regions where UV-CPL of the same helicity is actually observed over large spatial areas.

  19. Synthesis of Novel Homo-N-Nucleoside Analogs Composed of a Homo-1,4-Dioxane Sugar Analog and Substituted 1,3,5-Triazine Base Equivalents

    Directory of Open Access Journals (Sweden)

    Qiang Yu

    2008-12-01

    Full Text Available Enantioselective syntheses from dimethyl tartrate of 1,3,5-triazine homo-N-nucleoside analogs, containing a 1,4-dioxane moiety replacing the sugar unit in natural nucleosides, were accomplished. The triazine heterocycle in the nucleoside analogs was further substituted with combinations of NH2, OH and Cl in the 2,4-triazine positions.

  20. Supporting Analogy-based Effort Estimation with the Use of Ontologies

    Directory of Open Access Journals (Sweden)

    Joanna Kowalska

    2014-06-01

    Full Text Available The paper concerns effort estimation of software development projects, in particular, at the level of product delivery stages. It proposes a new approach to model project data to support expert-supervised analogy-based effort estimation. The data is modeled using Semantic Web technologies, such as Resource Description Framework (RDF and Ontology Language for the Web (OWL. Moreover, in the paper, we define a method of supervised case-based reasoning. The method enables to search for similar projects’ tasks at different levels of abstraction. For instance, instead of searching for a task performed by a specific person, one could look for tasks performed by people with similar capabilities. The proposed method relies on ontology that defines the core concepts and relationships. However, it is possible to introduce new classes and relationships, without the need of altering the search mechanisms. Finally, we implemented a prototype tool that was used to preliminary validate the proposed approach. We observed that the proposed approach could potentially help experts in estimating non-trivial tasks that are often underestimated.

  1. A Vague Decision Method for Analog Circuit Fault Diagnosis Based on Description Sphere

    Institute of Scientific and Technical Information of China (English)

    LUO Hui; WANG Youren; CUI Jiang

    2011-01-01

    This paper proposes a vague decision method for analog circuit fault diagnosis based on description sphere.Firstly,the proposed method uses the wavelet transform as the preprocessor to extract fault features from the output voltages of the circuit under test (CUT).And then,each class sample is trained to produce a minimum description sphere.Finally,the test samples are detected by a defined vague decision rule,which is based on the vague weight distance between the test data and the center of description sphere.The defined decision rule fuses the truth and false membership degrees of the test sample and the weight of the description sphere,and it can effectively deal with the uncertain information.The reliability of the defined decision rule is proved theoretically.This new diagnostic method is first applied to testing two actual circuits,and then it is compared with other two diagnostic methods.The experimental results show that the proposed technique can achieve good performance and reduce the diagnostic time.

  2. The pyruvic acid analog 3-bromopyruvate interferes with the tetrazolium reagent MTS in the evaluation of cytotoxicity.

    Science.gov (United States)

    Ganapathy-Kanniappan, Shanmugasundaram; Geschwind, Jean-Francois H; Kunjithapatham, Rani; Buijs, Manon; Syed, Labiq H; Rao, Pramod P; Ota, Shinichi; Vali, Mustafa

    2010-04-01

    3-Bromopyruvate (3BrPA) is a pyruvate analog known for its alkylating property. Recently, several reports have documented the antiglycolytic and anticancer effects of 3BrPA and its potential for therapeutic applications. 3BrPA-mediated cytotoxicity has been evaluated in vitro by various methods including tetrazolium salt (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide)-based assays such as MTT, MTS, and so on. However, growing body of evidences has shown that tetrazolium reagent may interfere with the test compounds. In this study, we investigated whether the tetrazolium reagent interferes with the assessment of 3BrPA cytotoxicity. The results of the tetrazolium-based MTS assay were compared with 3 distinct cell viability detection methods, that is, Trypan Blue staining, ATP depletion, and Annexin V staining in 2 different cell lines, Vx-2 and HepG2. The MTS assay data showed false positive results by indicating increased cell viability at 1 mM and 2 mM 3BrPA whereas the other cell viability assays demonstrated that both Vx-2 and HepG2 cells are not viable at the same treatment conditions. In order to validate the direct interaction of 3BrPA with MTS reagent, we tested cell-free media incubated with different concentrations of 3BrPA. The results of cell-free media showed an increase in absorbance in a dose-dependent manner confirming the interaction of MTS with 3BrPA. Thus, our data clearly demonstrate that 3BrPA interferes with the accuracy of MTS-based cytotoxicity evaluation. Hence, we suggest that employing multiple methods of biochemical as well as morphological cytotoxicity assays is critical to evaluate 3BrPA-mediated cell death.

  3. Down-regulation of the Caffeic acid O-methyltransferase Gene in Switchgrass Reveals a Novel Monolignol Analog

    Energy Technology Data Exchange (ETDEWEB)

    Tschaplinski, Timothy J [ORNL; Standaert, Robert F [ORNL; Engle, Nancy L [ORNL; Martin, Madhavi Z [ORNL; Sangha, Amandeep K [ORNL; Parks, Jerry M [ORNL; Smith, Jeremy C [ORNL; Samuel, Reichel [ORNL; Pu, Yunqiao [ORNL; Ragauskas, A J [Georgia Institute of Technology; Hamilton, Choo Yieng [ORNL; Fu, Chunxiang [Noble Foundation; Wang, Zeng-Yu [Noble Foundation; Davison, Brian H [ORNL; Dixon, Richard A [Noble Foundation; Mielenz, Jonathan R [ORNL

    2012-01-01

    Down-regulation of the caffeic acid 3-O-methyltransferase (COMT) gene in the lignin biosynthetic pathway of switchgrass (Panicum virgatum) resulted in cell walls of transgenic plants releasing more constituent sugars after pretreatment by dilute acid and treatment with glycosyl hydrolases from an added enzyme preparation and from Clostridium thermocellum. Fermentation of both wild-type and transgenic switchgrass after milder hot water pretreatment with no water washing showed that only the transgenic switchgrass inhibited C. thermocellum. Gas chromatography-mass spectrometry-based metabolomics were undertaken on cell wall aqueous extracts to determine the nature of the microbial inhibitors, confirming the increased concentration of a number of phenolic acids and aldehydes that are known inhibitors of fermentation. Metabolomic analyses of the transgenic biomass additionally revealed the presence of a novel monolignol-like metabolite, identified as trans-3, 4-dimethoxy-5-hydroxycinnamyl alcohol (iso-sinapyl alcohol) in both non-pretreated, as well as hot water pretreated samples. Although there was no indication that iso-sinapyl alcohol was integrated into the cell wall, diversion of substrates from sinapyl alcohol to free iso-sinapyl alcohol, its glucoside, and associated upstream lignin pathway changes, including increased phenolic aldehydes and acids, are associated with more facile cell wall deconstruction, and to the observed inhibitory effect on microbial growth.

  4. Urea, glycolic acid, and glycerol in an organic residue produced by ultraviolet irradiation of interstellar/pre-cometary ice analogs.

    Science.gov (United States)

    Nuevo, Michel; Bredehöft, Jan Hendrik; Meierhenrich, Uwe J; d'Hendecourt, Louis; Thiemann, Wolfram H-P

    2010-03-01

    More than 50 stable organic molecules have been detected in the interstellar medium (ISM), from ground-based and onboard-satellite astronomical observations, in the gas and solid phases. Some of these organics may be prebiotic compounds that were delivered to early Earth by comets and meteorites and may have triggered the first chemical reactions involved in the origin of life. Ultraviolet irradiation of ices simulating photoprocesses of cold solid matter in astrophysical environments have shown that photochemistry can lead to the formation of amino acids and related compounds. In this work, we experimentally searched for other organic molecules of prebiotic interest, namely, oxidized acid labile compounds. In a setup that simulates conditions relevant to the ISM and Solar System icy bodies such as comets, a condensed CH(3)OH:NH(3) = 1:1 ice mixture was UV irradiated at approximately 80 K. The molecular constituents of the nonvolatile organic residue that remained at room temperature were separated by capillary gas chromatography and identified by mass spectrometry. Urea, glycolic acid, and glycerol were detected in this residue, as well as hydroxyacetamide, glycerolic acid, and glycerol amide. These organics are interesting target molecules to be searched for in space. Finally, tentative mechanisms of formation for these compounds under interstellar/pre-cometary conditions are proposed.

  5. VHDL-based programming environment for Floating-Gate analog memory cell

    Directory of Open Access Journals (Sweden)

    Carlos Alberto dos Reis Filho

    2005-02-01

    Full Text Available An implementation in CMOS technology of a Floating-Gate Analog Memory Cell and Programming Environment is presented. A digital closed-loop control compares a reference value set by user and the memory output and after cycling, the memory output is updated and the new value stored. The circuit can be used as analog trimming for VLSI applications where mechanical trimming associated with postprocessing chip is prohibitive due to high costs.

  6. Identification of potent 11mer glucagon-like peptide-1 receptor agonist peptides with novel C-terminal amino acids: Homohomophenylalanine analogs.

    Science.gov (United States)

    Haque, Tasir S; Lee, Ving G; Riexinger, Douglas; Lei, Ming; Malmstrom, Sarah; Xin, Li; Han, Songping; Mapelli, Claudio; Cooper, Christopher B; Zhang, Ge; Ewing, William R; Krupinski, John

    2010-05-01

    We report the identification of potent agonists of the Glucagon-Like Peptide-1 Receptor (GLP-1R). These compounds are short, 11 amino acid peptides containing several unnatural amino acids, including (in particular) analogs of homohomophenylalanine (hhPhe) at the C-terminal position. Typically the functional activity of the more potent peptides in this class is in the low picomolar range in an in vitro cAMP assay, with one example demonstrating excellent in vivo activity in an ob/ob mouse model of diabetes.

  7. Empirical source strength correlations for rans-based acoustic analogy methods

    Science.gov (United States)

    Kube-McDowell, Matthew Tyndall

    JeNo is a jet noise prediction code based on an acoustic analogy method developed by Mani, Gliebe, Balsa, and Khavaran. Using the flow predictions from a standard Reynolds-averaged Navier-Stokes computational fluid dynamics solver, JeNo predicts the overall sound pressure level and angular spectra for high-speed hot jets over a range of observer angles, with a processing time suitable for rapid design purposes. JeNo models the noise from hot jets as a combination of two types of noise sources; quadrupole sources dependent on velocity fluctuations, which represent the major noise of turbulent mixing, and dipole sources dependent on enthalpy fluctuations, which represent the effects of thermal variation. These two sources are modeled by JeNo as propagating independently into the far-field, with no cross-correlation at the observer location. However, high-fidelity computational fluid dynamics solutions demonstrate that this assumption is false. In this thesis, the theory, assumptions, and limitations of the JeNo code are briefly discussed, and a modification to the acoustic analogy method is proposed in which the cross-correlation of the two primary noise sources is allowed to vary with the speed of the jet and the observer location. As a proof-of-concept implementation, an empirical correlation correction function is derived from comparisons between JeNo's noise predictions and a set of experimental measurements taken for the Air Force Aero-Propulsion Laboratory. The empirical correlation correction is then applied to JeNo's predictions of a separate data set of hot jets tested at NASA's Glenn Research Center. Metrics are derived to measure the qualitative and quantitative performance of JeNo's acoustic predictions, and the empirical correction is shown to provide a quantitative improvement in the noise prediction at low observer angles with no freestream flow, and a qualitative improvement in the presence of freestream flow. However, the results also demonstrate

  8. A Fault Dictionary-Based Fault Diagnosis Approach for CMOS Analog Integrated Circuits

    Directory of Open Access Journals (Sweden)

    Mouna Karmani

    2011-10-01

    Full Text Available In this paper, we propose a simulation-before-test (SBT fault diagnosis methodology based on the use of afault dictionary approach. This technique allows the detection and localization of the most likely defects ofopen-circuit type occurring in Complementary Metal–Oxide–Semiconductor (CMOS analog integratedcircuits (ICs interconnects. The fault dictionary is built by simulating the most likely defects causing thefaults to be detected at the layout level. Then, for each injected fault, the spectre’s frequency responses andthe power consumption obtained by simulation are stored in a table which constitutes the fault dictionary.In fact, each line in the fault dictionary constitutes a fault signature used to identify and locate aconsidered defect. When testing, the circuit under test is excited with the same stimulus, and the responsesobtained are compared to the stored ones. To prove the efficiency of the proposed technique, a full customCMOS operational amplifier is implemented in 0.25 μm technology and the most likely faults of opencircuittype are deliberately injected and simulated at the layout level.

  9. Synthesis and Biological Evaluation of 2-Aminobenzothiazole and Benzimidazole Analogs Based on the Clathrodin Structure.

    Science.gov (United States)

    Montalvão, Sofia; Leino, Teppo O; Kiuru, Paula S; Lillsunde, Katja-Emilia; Yli-Kauhaluoma, Jari; Tammela, Päivi

    2016-02-01

    A series of 2-aminobenzothiazole and benzimidazole analogs based on the clathrodin scaffold was synthesized and investigated for their antimicrobial and antiproliferative activities as well as for their effects in hepatitis C virus (HCV) replicon model. Compound 7, derived from 2-aminobenzothiazole, exhibited moderate antimicrobial activity only against the Gram-positive bacterium, Enterococcus faecalis. In the antiviral assay, compounds 4d and 7 were found to suppress the HCV replicon by >70%, but also to exhibit cytotoxicity against the host cells (35 and 44%, respectively). Compounds 4a and 7 demonstrated good activity in the antiproliferative assays on the human melanoma cell line A-375. To assess the selectivity of the effects between cancerous and noncancerous cells, a mouse fibroblast cell line was used. The IC50 values for compound 7 against the melanoma cell line A-375 and the fibroblast cell line BALB/c 3T3 were 16 and 71 µM, respectively, yielding fourfold selectivity toward the cancer cell line. These results suggest that compound 7 should be studied further in order to fully explore its potential for drug development.

  10. A combined noise analysis and power supply current based testing of CMOS analog integrated circuits

    Science.gov (United States)

    Srivastava, Ashok; Pulendra, Vani K.; Yellampalli, Siva

    2005-05-01

    A technique integrating the noise analysis based testing and the conventional power supply current testing of CMOS analog integrated circuits is presented for bridging type faults due to manufacturing defects. The circuit under test (CUT) is a CMOS amplifier designed for operation at +/- 2.5 V and implemented in 1.5 μm CMOS process. The faults simulating possible manufacturing defects have been introduced using the fault injection transistors. The amplifier circuit is analyzed and simulated in SPICE for its performance with and without fault injections. The faults in the CUT are identified by observing the variation in the equivalent noise voltage at the output of CUT. In power supply current testing, the current (IPS) through the power supply voltage, VDD is measured under the application of an AC input stimulus. The effect of parametric variation is taken into consideration by determining the tolerance limit using the Monte-Carlo analysis. The fault is identified if the power supply current, IPS lies outside the deviation given by Monte-Carlo analysis. Simulation results are in close agreement with the corresponding experimental values.

  11. A Fault Dictionary-Based Fault Diagnosis Approach for CMOS Analog Integrated Circuits

    Directory of Open Access Journals (Sweden)

    Mouna Karmani

    2011-09-01

    Full Text Available In this paper, we propose a simulation-before-test (SBT fault diagnosis methodology based on the use of a fault dictionary approach. This technique allows the detection and localization of the most likely defects of open-circuit type occurring in Complementary Metal–Oxide–Semiconductor (CMOS analog integrated circuits (ICs interconnects. The fault dictionary is built by simulating the most likely defects causing the faults to be detected at the layout level. Then, for each injected fault, the spectre’s frequency responses and the power consumption obtained by simulation are stored in a table which constitutes the fault dictionary.In fact, each line in the fault dictionary constitutes a fault signature used to identify and locate a considered defect. When testing, the circuit under test is excited with the same stimulus, and the responses obtained are compared to the stored ones. To prove the efficiency of the proposed technique, a full custom CMOS operational amplifier is implemented in 0.25 μm technology and the most likely faults of open circuit type are deliberately injected and simulated at the layout level.

  12. A New Digital to Analog Converter Based on Low-Offset Bandgap Reference

    Directory of Open Access Journals (Sweden)

    Jinpeng Qiu

    2017-01-01

    Full Text Available This paper presents a new 12-bit digital to analog converter (DAC circuit based on a low-offset bandgap reference (BGR circuit with two cascade transistor structure and two self-contained feedback low-offset operational amplifiers to reduce the effects of offset operational amplifier voltage effect on the reference voltage, PMOS current-mirror mismatch, and its channel modulation. A Start-Up circuit with self-bias current architecture and multipoint voltage monitoring is employed to keep the BGR circuit working properly. Finally, a dual-resistor ladder DAC-Core circuit is used to generate an accuracy DAC output signal to the buffer operational amplifier. The proposed circuit was fabricated in CSMC 0.5 μm 5 V 1P4M process. The measured differential nonlinearity (DNL of the output voltages is less than 0.45 LSB and integral nonlinearity (INL less than 1.5 LSB at room temperature, consuming only 3.5 mW from a 5 V supply voltage. The DNL and INL at −55°C and 125°C are presented as well together with the discussion of possibility of improving the DNL and INL accuracy in future design.

  13. Charge plasma technique based dopingless accumulation mode junctionless cylindrical surrounding gate MOSFET: analog performance improvement

    Science.gov (United States)

    Trivedi, Nitin; Kumar, Manoj; Haldar, Subhasis; Deswal, S. S.; Gupta, Mridula; Gupta, R. S.

    2017-09-01

    A charge plasma technique based dopingless (DL) accumulation mode (AM) junctionless (JL) cylindrical surrounding gate (CSG) MOSFET has been proposed and extensively investigated. Proposed device has no physical junction at source to channel and channel to drain interface. The complete silicon pillar has been considered as undoped. The high free electron density or induced N+ region is designed by keeping the work function of source/drain metal contacts lower than the work function of undoped silicon. Thus, its fabrication complexity is drastically reduced by curbing the requirement of high temperature doping techniques. The electrical/analog characteristics for the proposed device has been extensively investigated using the numerical simulation and are compared with conventional junctionless cylindrical surrounding gate (JL-CSG) MOSFET with identical dimensions. For the numerical simulation purpose ATLAS-3D device simulator is used. The results show that the proposed device is more short channel immune to conventional JL-CSG MOSFET and suitable for faster switching applications due to higher I ON/ I OFF ratio.

  14. Phase-unwrapping approach based on dual-frequency analog structured light

    Science.gov (United States)

    Wang, Beiyi; Yu, Xiaoyang; Wu, Haibin; Zhang, Jixun; Meng, Xiaoliang

    2017-01-01

    Among the structured light 3-D measurement approaches, the multi-period analog encoded structured light (AESL) has advantages such as high resolution and high sampling rate owing to its point-to-point calculation method. However, phase unwrapping is always a problem when employing the multi-period AESL. Therefore, we propose a novel phase unwrapping approach based on dual-frequency AESL. We demonstrate the principle of the proposed phase unwrapping approach through theoretical analysis and the applicable condition for the proposed approach is determined through error analysis. We perform experiments using the proposed and classical heterodyne approaches and compare the results. The experimental results for the standard plane show that the average value of the root mean square error with the heterodyne approach is 1.08 mm, and that with the proposed approach is 0.62 mm, which is a reduction by 43%. Further, the experimental results for the complicated surfaces show that the reconstructed object obtained using the proposed approach is fine and smooth, and the detailed features are clearly displayed. The experiments verify both the accuracy and the suitability of the proposed approach.

  15. Analog computing

    CERN Document Server

    Ulmann, Bernd

    2013-01-01

    This book is a comprehensive introduction to analog computing. As most textbooks about this powerful computing paradigm date back to the 1960s and 1970s, it fills a void and forges a bridge from the early days of analog computing to future applications. The idea of analog computing is not new. In fact, this computing paradigm is nearly forgotten, although it offers a path to both high-speed and low-power computing, which are in even more demand now than they were back in the heyday of electronic analog computers.

  16. Multichannel analog-to-digital converters based on current mirrors for the optical systems

    Science.gov (United States)

    Krasilenko, Vladimir G.; Nikolskyy, A. I.; Nikolska, M. A.; Lobodzinska, R. F.

    2011-12-01

    The paper considers results of designing and modeling analogue-digital converters (ADC) based on current mirrors for the optical systems and neural networks with parallel inputs-outputs. Such ADC, named us multichannel analog-todigital converters based on current mirrors (M ADC CM). Compared with usual converters, for example, reading, a bitby- bit equilibration, and so forth, have a number of advantages: high speed and reliability, simplicity, small power consumption, the big degree of integration in linear and matrix structures. The considered aspects of designing of M_ADC CM in binary codes. Base digit cells (ABC) of such M_ADC CM, series-pipelined are connected in structures, consist from 20-30 CMOS the transistors, one photodiode, have low (1,5-3,5) supply voltage, work in current modes with the maximum values of currents (10-40)μA. Therefore such new principles of realization high-speed low-discharge M_ADC CM have allowed, as have shown modeling experiments, to reach time of transformation less than 20-30 nS at 5-6 bits of a binary code and the general power 1-5 mW. The quantity easily cascadable ABC depends on wordlength ADC, and makes n, and provides quantity of levels of quantization equal N=2n. Such simple enough on structure M ADC CM, having low power consumption CMOS-technologies has made 40 MHz, and can be increased 10 times) and accuracy (Δquantization 156,25nA for I max10μA) characteristics is show. The range can be transformed optical signals, taking into account sensitivity of modern photodetectors makes 20-200 μW in such ADC. M_ADC CM open new prospects for realization linear and matrix (with picture operands) micro photoelectronic structures which are necessary for neural networks, digital optoelectronic processors, neurofuzzy controllers, and so forth.

  17. Model, analysis, and evaluation of the effects of analog VLSI arithmetic on linear subspace-based image recognition.

    Science.gov (United States)

    Carvajal, Gonzalo; Figueroa, Miguel

    2014-07-01

    Typical image recognition systems operate in two stages: feature extraction to reduce the dimensionality of the input space, and classification based on the extracted features. Analog Very Large Scale Integration (VLSI) is an attractive technology to achieve compact and low-power implementations of these computationally intensive tasks for portable embedded devices. However, device mismatch limits the resolution of the circuits fabricated with this technology. Traditional layout techniques to reduce the mismatch aim to increase the resolution at the transistor level, without considering the intended application. Relating mismatch parameters to specific effects in the application level would allow designers to apply focalized mismatch compensation techniques according to predefined performance/cost tradeoffs. This paper models, analyzes, and evaluates the effects of mismatched analog arithmetic in both feature extraction and classification circuits. For the feature extraction, we propose analog adaptive linear combiners with on-chip learning for both Least Mean Square (LMS) and Generalized Hebbian Algorithm (GHA). Using mathematical abstractions of analog circuits, we identify mismatch parameters that are naturally compensated during the learning process, and propose cost-effective guidelines to reduce the effect of the rest. For the classification, we derive analog models for the circuits necessary to implement Nearest Neighbor (NN) approach and Radial Basis Function (RBF) networks, and use them to emulate analog classifiers with standard databases of face and hand-writing digits. Formal analysis and experiments show how we can exploit adaptive structures and properties of the input space to compensate the effects of device mismatch at the application level, thus reducing the design overhead of traditional layout techniques. Results are also directly extensible to multiple application domains using linear subspace methods.

  18. A reuse-based framework for the design of analog and mixed-signal ICs

    Science.gov (United States)

    Castro-Lopez, Rafael; Fernandez, Francisco V.; Rodriguez Vazquez, Angel

    2005-06-01

    Despite the spectacular breakthroughs of the semiconductor industry, the ability to design integrated circuits (ICs) under stringent time-to-market (TTM) requirements is lagging behind integration capacity, so far keeping pace with still valid Moore"s Law. The resulting gap is threatening with slowing down such a phenomenal growth. The design community believes that it is only by means of powerful CAD tools and design methodologies - and, possibly, a design paradigm shift - that this design gap can be bridged. In this sense, reuse-based design is seen as a promising solution, and concepts such as IP Block, Virtual Component, and Design Reuse have become commonplace thanks to the significant advances in the digital arena. Unfortunately, the very nature of analog and mixed-signal (AMS) design has hindered a similar level of consensus and development. This paper presents a framework for the reuse-based design of AMS circuits. The framework is founded on three key elements: (1) a CAD-supported hierarchical design flow that facilitates the incorporation of AMS reusable blocks, reduces the overall design time, and expedites the management of increasing AMS design complexity; (2) a complete, clear definition of the AMS reusable block, structured into three separate facets or views: the behavioral, structural, and layout facets, the two first for top-down electrical synthesis and bottom-up verification, the latter used during bottom-up physical synthesis; (3) the design for reusability set of tools, methods, and guidelines that, relying on intensive parameterization as well as on design knowledge capture and encapsulation, allows to produce fully reusable AMS blocks. A case study and a functional silicon prototype demonstrate the validity of the paper"s proposals.

  19. Optical Flow in a Smart Sensor Based on Hybrid Analog-Digital Architecture

    Directory of Open Access Journals (Sweden)

    Pablo Guzmán

    2010-03-01

    Full Text Available The purpose of this study is to develop a motion sensor (delivering optical flow estimations using a platform that includes the sensor itself, focal plane processing resources, and co-processing resources on a general purpose embedded processor. All this is implemented on a single device as a SoC (System-on-a-Chip. Optical flow is the 2-D projection into the camera plane of the 3-D motion information presented at the world scenario. This motion representation is widespread well-known and applied in the science community to solve a wide variety of problems. Most applications based on motion estimation require work in real-time; hence, this restriction must be taken into account. In this paper, we show an efficient approach to estimate the motion velocity vectors with an architecture based on a focal plane processor combined on-chip with a 32 bits NIOS II processor. Our approach relies on the simplification of the original optical flow model and its efficient implementation in a platform that combines an analog (focal-plane and digital (NIOS II processor. The system is fully functional and is organized in different stages where the early processing (focal plane stage is mainly focus to pre-process the input image stream to reduce the computational cost in the post-processing (NIOS II stage. We present the employed co-design techniques and analyze this novel architecture. We evaluate the system’s performance and accuracy with respect to the different proposed approaches described in the literature. We also discuss the advantages of the proposed approach as well as the degree of efficiency which can be obtained from the focal plane processing capabilities of the system. The final outcome is a low cost smart sensor for optical flow computation with real-time performance and reduced power consumption that can be used for very diverse application domains.

  20. Optical flow in a smart sensor based on hybrid analog-digital architecture.

    Science.gov (United States)

    Guzmán, Pablo; Díaz, Javier; Agís, Rodrigo; Ros, Eduardo

    2010-01-01

    The purpose of this study is to develop a motion sensor (delivering optical flow estimations) using a platform that includes the sensor itself, focal plane processing resources, and co-processing resources on a general purpose embedded processor. All this is implemented on a single device as a SoC (System-on-a-Chip). Optical flow is the 2-D projection into the camera plane of the 3-D motion information presented at the world scenario. This motion representation is widespread well-known and applied in the science community to solve a wide variety of problems. Most applications based on motion estimation require work in real-time; hence, this restriction must be taken into account. In this paper, we show an efficient approach to estimate the motion velocity vectors with an architecture based on a focal plane processor combined on-chip with a 32 bits NIOS II processor. Our approach relies on the simplification of the original optical flow model and its efficient implementation in a platform that combines an analog (focal-plane) and digital (NIOS II) processor. The system is fully functional and is organized in different stages where the early processing (focal plane) stage is mainly focus to pre-process the input image stream to reduce the computational cost in the post-processing (NIOS II) stage. We present the employed co-design techniques and analyze this novel architecture. We evaluate the system's performance and accuracy with respect to the different proposed approaches described in the literature. We also discuss the advantages of the proposed approach as well as the degree of efficiency which can be obtained from the focal plane processing capabilities of the system. The final outcome is a low cost smart sensor for optical flow computation with real-time performance and reduced power consumption that can be used for very diverse application domains.

  1. Unity and disunity in evolutionary sciences: process-based analogies open common research avenues for biology and linguistics.

    Science.gov (United States)

    List, Johann-Mattis; Pathmanathan, Jananan Sylvestre; Lopez, Philippe; Bapteste, Eric

    2016-08-20

    For a long time biologists and linguists have been noticing surprising similarities between the evolution of life forms and languages. Most of the proposed analogies have been rejected. Some, however, have persisted, and some even turned out to be fruitful, inspiring the transfer of methods and models between biology and linguistics up to today. Most proposed analogies were based on a comparison of the research objects rather than the processes that shaped their evolution. Focusing on process-based analogies, however, has the advantage of minimizing the risk of overstating similarities, while at the same time reflecting the common strategy to use processes to explain the evolution of complexity in both fields. We compared important evolutionary processes in biology and linguistics and identified processes specific to only one of the two disciplines as well as processes which seem to be analogous, potentially reflecting core evolutionary processes. These new process-based analogies support novel methodological transfer, expanding the application range of biological methods to the field of historical linguistics. We illustrate this by showing (i) how methods dealing with incomplete lineage sorting offer an introgression-free framework to analyze highly mosaic word distributions across languages; (ii) how sequence similarity networks can be used to identify composite and borrowed words across different languages; (iii) how research on partial homology can inspire new methods and models in both fields; and (iv) how constructive neutral evolution provides an original framework for analyzing convergent evolution in languages resulting from common descent (Sapir's drift). Apart from new analogies between evolutionary processes, we also identified processes which are specific to either biology or linguistics. This shows that general evolution cannot be studied from within one discipline alone. In order to get a full picture of evolution, biologists and linguists need to

  2. A Novel Approach To Diagnosis Of Analog Circuit Incipient Faults Based On KECA And OAO LSSVM

    Directory of Open Access Journals (Sweden)

    Zhang Chaolong

    2015-06-01

    Full Text Available Correct incipient identification of an analog circuit fault is conducive to the health of the analog circuit, yet very difficult. In this paper, a novel approach to analog circuit incipient fault identification is presented. Time responses are acquired by sampling outputs of the circuits under test, and then the responses are decomposed by the wavelet transform in order to generate energy features. Afterwards, lower-dimensional features are produced through the kernel entropy component analysis as samples for training and testing a one-against-one least squares support vector machine. Simulations of the incipient fault diagnosis for a Sallen-Key band-pass filter and a two-stage four-op-amp bi-quad low-pass filter demonstrate the diagnosing procedure of the proposed approach, and also reveal that the proposed approach has higher diagnosis accuracy than the referenced methods.

  3. Zero-Gravity Locomotion Simulators: New Ground-Based Analogs for Microgravity Exercise Simulation

    Science.gov (United States)

    Perusek, Gail P.; DeWitt, John K.; Cavanagh, Peter R.; Grodsinsky, Carlos M.; Gilkey, Kelly M.

    2007-01-01

    Maintaining health and fitness in crewmembers during space missions is essential for preserving performance for mission-critical tasks. NASA's Exercise Countermeasures Project (ECP) provides space exploration exercise hardware and monitoring requirements that lead to devices that are reliable, meet medical, vehicle, and habitat constraints, and use minimal vehicle and crew resources. ECP will also develop and validate efficient exercise prescriptions that minimize daily time needed for completion of exercise yet maximize performance for mission activities. In meeting these mission goals, NASA Glenn Research Center (Cleveland, OH, USA), in collaboration with the Cleveland Clinic (Cleveland, Ohio, USA), has developed a suite of zero-gravity locomotion simulators and associated technologies to address the need for ground-based test analog capability for simulating in-flight (microgravity) and surface (partial-gravity) exercise to advance the health and safety of astronaut crews and the next generation of space explorers. Various research areas can be explored. These include improving crew comfort during exercise, and understanding joint kinematics and muscle activation pattern differences relative to external loading mechanisms. In addition, exercise protocol and hardware optimization can be investigated, along with characterizing system dynamic response and the physiological demand associated with advanced exercise device concepts and performance of critical mission tasks for Exploration class missions. Three zero-gravity locomotion simulators are currently in use and the research focus for each will be presented. All of the devices are based on a supine subject suspension system, which simulates a reduced gravity environment by completely or partially offloading the weight of the exercising test subject s body. A platform for mounting treadmill is positioned perpendicularly to the test subject. The Cleveland Clinic Zero-g Locomotion Simulator (ZLS) utilizes a

  4. Enantiomeric excesses induced in amino acids by ultraviolet circularly polarized light irradiation of extraterrestrial ice analogs: A possible source of asymmetry for prebiotic chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Modica, Paola; De Marcellus, Pierre; D' Hendecourt, Louis Le Sergeant [Univ. Paris-Sud, Institut d' Astrophysique Spatiale, UMR 8617, F-91405 Orsay (France); Meinert, Cornelia; Meierhenrich, Uwe J. [Univ. Nice Sophia Antipolis, Institut de Chimie de Nice, UMR 7272 CNRS, F-06108 Nice (France); Nahon, Laurent, E-mail: laurent.nahon@synchrotron-soleil.fr, E-mail: ldh@ias.u-psud.fr [Synchrotron SOLEIL, F-91192 Gif-sur-Yvette (France)

    2014-06-10

    The discovery of meteoritic amino acids with enantiomeric excesses of the L-form (ee {sub L}) has suggested that extraterrestrial organic materials may have contributed to prebiotic chemistry and directed the initial occurrence of the ee {sub L} that further led to homochirality of amino acids on Earth. A proposed mechanism for the origin of ee {sub L} in meteorites involves an asymmetric photochemistry of extraterrestrial ices by UV circularly polarized light (CPL). We have performed the asymmetric synthesis of amino acids on achiral extraterrestrial ice analogs by VUV CPL, investigating the chiral asymmetry transfer at two different evolutionary stages at which the analogs were irradiated (regular ices and/or organic residues) and at two different photon energies (6.6 and 10.2 eV). We identify 16 distinct amino acids and precisely measure the L-enantiomeric excesses using the enantioselective GC × GC-TOFMS technique in five of them: α-alanine, 2,3-diaminopropionic acid, 2-aminobutyric acid, valine, and norvaline, with values ranging from ee {sub L} = –0.20% ± 0.14% to ee {sub L} = –2.54% ± 0.28%. The sign of the induced ee {sub L} depends on the helicity and the energy of CPL, but not on the evolutionary stage of the samples, and is the same for all five considered amino acids. Our results support an astrophysical scenario in which the solar system was formed in a high-mass star-forming region where icy grains were irradiated during the protoplanetary phase by an external source of CPL of a given helicity and a dominant energy, inducing a stereo-specific photochemistry.

  5. Characterization of facies and permeability patterns in carbonate reservoirs based on outcrop analogs. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Kerans, C.; Lucia, F.J.; Senger, R.K.; Fogg, G.E.; Nance, H.S.; Hovorka, S.D.

    1993-07-01

    The primary objective of this research is to develop methods for better describing the three-dimensional geometry of carbonate reservoir flow units as related to conventional or enhanced recovery of oil. San Andres and Grayburg reservoirs were selected for study because of the 13 Bbbl of remaining mobile oil and 17 Bbbl of residual oil in these reservoirs. The key data base is provided by detailed characterization of geologic facies and rock permeability in reservior-scale outcrops of the Permian San Andres Formation in the Guadalupe Mountains of New Mexico. Emphasis is placed on developing an outcrop analog for San Andres strata that can be used as (1) a guide to interpreting the regional and local geologic framework of the subsurface reservoirs (2) a data source illustrating the scales and patterns of variability of rock-fabric facies and petrophysical properties, particularly in lateral dimension, and on scales that cannot be studied during subsurface reservoir characterization. The research approach taken to achieve these objectives utilizes the integration of geologic description, geostatistical techniques, and reservoir flow simulation experiments. Results from this research show that the spatial distribution of facies relative to the waterflood direction can significantly affect how the reservoir produces. Bypassing of unswept oil occurs due to cross flow of injected water from high permeability zones into lower permeability zones were high permeability zones terminate. An area of unswept oil develops because of the slower advance of the water-injection front in the lower permeability zones. When the injection pattern is reversed, the cross-flow effect changes due to the different arrangements of rock-fabric flow units relative to the flow of injected water, and the sweep efficiency is significantly different. Flow across low-permeability mudstones occurs showing that these layers do not necessarily represent flow barriers.

  6. Nucleic Acid-Based Nanoconstructs

    Science.gov (United States)

    Focuses on the design, synthesis, characterization, and development of spherical nucleic acid constructs as effective nanotherapeutic, single-entity agents for the treatment of glioblastoma multiforme and prostate cancers.

  7. The Conjugate Acid-Base Chart.

    Science.gov (United States)

    Treptow, Richard S.

    1986-01-01

    Discusses the difficulties that beginning chemistry students have in understanding acid-base chemistry. Describes the use of conjugate acid-base charts in helping students visualize the conjugate relationship. Addresses chart construction, metal ions, buffers and pH titrations, and the organic functional groups and nonaqueous solvents. (TW)

  8. The Kidney and Acid-Base Regulation

    Science.gov (United States)

    Koeppen, Bruce M.

    2009-01-01

    Since the topic of the role of the kidneys in the regulation of acid base balance was last reviewed from a teaching perspective (Koeppen BM. Renal regulation of acid-base balance. Adv Physiol Educ 20: 132-141, 1998), our understanding of the specific membrane transporters involved in H+, HCO , and NH transport, and especially how these…

  9. Students' Alternate Conceptions on Acids and Bases

    Science.gov (United States)

    Pan, Hanqing; Henriques, Laura

    2015-01-01

    Knowing what students bring to the classroom can and should influence how we teach them. This study is a review of the literature associated with secondary and postsecondary students' ideas about acids and bases. It was found that there are six types of alternate ideas about acids and bases that students hold. These are: macroscopic properties of…

  10. The Kidney and Acid-Base Regulation

    Science.gov (United States)

    Koeppen, Bruce M.

    2009-01-01

    Since the topic of the role of the kidneys in the regulation of acid base balance was last reviewed from a teaching perspective (Koeppen BM. Renal regulation of acid-base balance. Adv Physiol Educ 20: 132-141, 1998), our understanding of the specific membrane transporters involved in H+, HCO , and NH transport, and especially how these…

  11. Crystal Structures of KPC-2 and SHV-1 β-Lactamases in Complex with the Boronic Acid Transition State Analog S02030.

    Science.gov (United States)

    Nguyen, Nhu Q; Krishnan, Nikhil P; Rojas, Laura J; Prati, Fabio; Caselli, Emilia; Romagnoli, Chiara; Bonomo, Robert A; van den Akker, Focco

    2016-01-04

    Resistance to expanded-spectrum cephalosporins and carbapenems has rendered certain strains of Klebsiella pneumoniae the most problematic pathogens infecting patients in the hospital and community. This broad-spectrum resistance to β-lactamases emerges in part via the expression of KPC-2 and SHV-1 β-lactamases and variants thereof. KPC-2 carbapenemase is particularly worrisome, as the genetic determinant encoding this β-lactamase is rapidly spread via plasmids. Moreover, KPC-2, a class A enzyme, is difficult to inhibit with mechanism-based inactivators (e.g., clavulanate). In order to develop new β-lactamase inhibitors (BLIs) to add to the limited available armamentarium that can inhibit KPC-2, we have structurally probed the boronic acid transition state analog S02030 for its inhibition of KPC-2 and SHV-1. S02030 contains a boronic acid, a thiophene, and a carboxyl triazole moiety. We present here the 1.54- and 1.87-Å resolution crystal structures of S02030 bound to SHV-1 and KPC-2 β-lactamases, respectively, as well as a comparative analysis of the S02030 binding modes, including a previously determined S02030 class C ADC-7 β-lactamase complex. S02030 is able to inhibit vastly different serine β-lactamases by interacting with the conserved features of these active sites, which includes (i) forming the bond with catalytic serine via the boron atom, (ii) positioning one of the boronic acid oxygens in the oxyanion hole, and (iii) utilizing its amide moiety to make conserved interactions across the width of the active site. In addition, S02030 is able to overcome more distantly located structural differences between the β-lactamases. This unique feature is achieved by repositioning the more polar carboxyl-triazole moiety, generated by click chemistry, to create polar interactions as well as reorient the more hydrophobic thiophene moiety. The former is aided by the unusual polar nature of the triazole ring, allowing it to potentially form a unique C-H…O 2

  12. How Science Students Can Learn about Unobservable Phenomena Using Computer-Based Analogies

    Science.gov (United States)

    Trey, L.; Khan, S.

    2008-01-01

    A novel instructional computer simulation that incorporates a dynamic analogy to represent Le Chatelier's Principle was designed to investigate the contribution of this feature to students' understanding. Two groups of 12th grade Chemistry students (n=15) interacted with the computer simulation during the study. Both groups did the same…

  13. Detecting lung cancer symptoms with analogic CNN algorithms based on a constrained diffusion template

    Energy Technology Data Exchange (ETDEWEB)

    Hirakawa, Satoshi; Nishio, Yoshifumi; Ushida, Akio; Ueno, Junji; Kasem, I.; Nishitani, Hiromu [Tokushima Univ. (Japan); Rekeczky, C.; Roska, T.

    1997-07-01

    In this article, a new type of diffusion template and an analogic CNN algorithm using this diffusion template for detecting some lung cancer symptoms in X-ray films are proposed. The performance of the diffusion template is investigated and our CNN algorithm is verified to detect some key lung cancer symptoms, successfully. (author)

  14. Entecavir Combined With Adefovir Ameliorates Patients With Chronic Hepatitis B Who Fail to Respond to Nucleotide (Acid) Analog Monotherapy.

    Science.gov (United States)

    Li, Xiang-Yong; You, Xu; Jie, Yu-Sheng; Lin, Guo-Li; Wu, Yuan-Kai; Huang, Ming-Xing; Zhang, Min; Li, Zhan-Yi; Xie, Dong-Ying; Gao, Zhi-Liang; Chong, Yu-Tian

    2017-05-01

    The aim of this study was to evaluate the efficacy and safety of entecavir (ETV) combined treatment with adefovir (ADV) on chronic hepatitic B (CHB) patients who failed to respond to nucleotide (acid) analog (NA) treatment. On this basis, the possible factors in the combined treatment of these patients will be analyzed. The safety, biochemical index, and the possible factors that might affect the ETV and ADV combined treatment at different points in time were retrospectively analyzed. The biochemical index included the following: virological response, hepatitis B virus (HBV) DNA decline, primary nonresponse, biochemical response, and the hepatitis B virus E antigen/hepatitis B virus E antibody seroconversion rate. There were 94 CHB patients and compensated liver cirrhosis patients who received ETV plus ADV treatment for over 12 weeks after failure of treatment with NAs. The authors have also investigated 76 CHB patients (80.9%) and 18 hepatitis B cirrhosis patients (19.1%) in this study. The HBV DNA baseline was 4.4 ± 1.4 log10 IU/mL, and the positive rate of HBeAg before salvage treatment was 78.7% (74/94). The sample sizes were 94, 78, 42, 10, 6, and 1 for follow-up of 24, 48, 96, 144, 192, and 240 weeks, respectively. The virological responses (HBV DNA < 2 log10 IU/mL) and biochemical responses were 52.1%, 74.3%, and 90.4% and 63.1%, 61.6%, and 81.1%, respectively, at 24, 48, and 96 weeks, which showed significant differences (P < 0.001 and P < 0.005, respectively). The HBV DNA decline was presented as mean ± SEM, which were 1.53 ± 1.23, 1.75 ± 1.37, 2.07 ± 1.54, and 2.39 ± 1.77 log10 IU/mL at 12, 24, 48, and 96 weeks, respectively. They showed significant differences compared with the baseline (χ = 8.084, P < 0.05). The rate of primary nonresponse was 30.9% (29/94), and the primary treatment failure rates were 26.6% (25/94), 24.4% (19/78), and 4.8% (2/42) at 24, 48, and 96 weeks, respectively. They all have statistical difference (P = 0.011 < 0

  15. Distributed Episodic and Analogical Reasoning (DEAR)

    Science.gov (United States)

    2010-04-01

    ends analysis Carbonell 1983 Modeling of Analogy Making Structure Mapping Theory (SMT) Gentner 1984 Agent based approach to analogy making...Mapping Engine (SME) Forbus 1990 Learning by analogy with larger domains Prodigy/Analogy Veloso and Carbonell 1991 Analogical Retrieval Engine MAC/FAC

  16. Synthesis of Marine α-Methoxylated Fatty Acid Analogs that Effectively Inhibit the Topoisomerase IB from Leishmania donovani with a Mechanism Different from that of Camptothecin

    Directory of Open Access Journals (Sweden)

    Rosa M. Reguera

    2013-09-01

    Full Text Available Sponges biosynthesize α-methoxylated fatty acids with unusual biophysical and biological properties and in some cases they display enhanced anticancer activities. However, the antiprotozoal properties of the α-methoxylated fatty acids have been less studied. In this work, we describe the total synthesis of (5Z,9Z-(±-2-methoxy-5, 9-eicosadienoic acid (1 and its acetylenic analog (±-2-methoxy-5,9-eicosadiynoic acid (2, and report that they inhibit (EC50 values between 31 and 22 µM the Leishmania donovani DNA topoisomerase IB enzyme (LdTopIB. The inhibition of LdTopIB (EC50 = 53 µM by the acid (±-2-methoxy-6-icosynoic acid (12 was studied as well. The potency of LdTopIB inhibition followed the trend 2 > 1 > 12, indicating that the effectiveness of inhibition depends on the degree of unsaturation. All of the studied α-methoxylated fatty acids failed to inhibit the human topoisomerase IB enzyme (hTopIB at 100 µM. However, the α-methoxylated fatty acids were capable of inhibiting an active but truncated LdTopIB with which camptothecin (CPT cannot interact suggesting that the methoxylated fatty acids inhibit LdTopIB with a mechanism different from that of CPT. The diunsaturated fatty acids displayed low cytotoxicity towards Leishmania infantum promastigotes (EC50 values between 260 and 240 µM, but 12 displayed a better cytotoxicity towards Leishmania donovani promastigotes (EC50 = 100 µM and a better therapeutic index.

  17. Mechanical Analogy-based Iterative Method for Solving a System of Linear Equations

    Directory of Open Access Journals (Sweden)

    Yu. V. Berchun

    2015-01-01

    Full Text Available The paper reviews prerequisites to creating a variety of the iterative methods to solve a system of linear equations (SLE. It considers the splitting methods, variation-type methods, projection-type methods, and the methods of relaxation.A new iterative method based on mechanical analogy (the movement without resistance of a material point, that is connected by ideal elastically-linear constraints with unending guides defined by equations of solved SLE. The mechanical system has the unique position of stable equilibrium, the coordinates of which correspond to the solution of linear algebraic equation. The model of the mechanical system is a system of ordinary differential equations of the second order, integration of which allows you to define the point trajectory. In contrast to the classical methods of relaxation the proposed method does not ensure a trajectory passage through the equilibrium position. Thus the convergence of the method is achieved through the iterative stop of a material point at the moment it passes through the next (from the beginning of the given iteration minimum of potential energy. After that the next iteration (with changed initial coordinates starts.A resource-intensive process of numerical integration of differential equations in order to obtain a precise law of motion (at each iteration is replaced by defining its approximation. The coefficients of the approximating polynomial of the fourth order are calculated from the initial conditions, including higher-order derivatives. The resulting approximation enables you to evaluate the kinetic energy of a material point to calculate approximately the moment of time to reach the maximum kinetic energy (and minimum of the potential one, i.e. the end of the iteration.The software implementation is done. The problems with symmetric positive definite matrix, generated as a result of using finite element method, allowed us to examine a convergence rate of the proposed method

  18. Putting Thought in Accordance with Things: The Demise of Animal-Based Analogies for Plant Functions

    Science.gov (United States)

    Barker, Miles

    Scientists' attempts to understand plant functions by ascribing animal functions to plants - the analogist tradition, derived from Aristotle - began to be superseded in Europe by an experimentalist tradition in the seventeenth century. In classrooms today, science students learning about plant functions (exemplified here by the topic of transpiration) face a parallel dilemma: the pitching of their own habitual mental processes of analogy building (enhanced by the suggestive morphology of plants)and the persuasiveness of everyday language (for example, about plants and water)against the new experimental evidence presented by the teacher. In the case oftranspiration, six practical suggestions whereby teachers can support students in thisstruggle to put their thoughts (especially everyday mental models) in accordance withthings (classroom experimental evidence) are advanced. The wider implications forhow we teach about Living Things, and how we view the status of analogies in sciencegenerally, are discussed.

  19. Space Station Habitability Recommendations Based on a Systematic Comparative Analysis of Analogous Conditions

    Science.gov (United States)

    Stuster, Jack W.

    1986-01-01

    Conditions analogous to the proposed NASA Space Station are systematically analyzed in order to extrapolate design guidelines and recommendations concerning habitability and crew productivity. Analogous environments studied included Skylab, Sealab, Tektite, submarines, Antarctic stations and oil drilling platforms, among others. These analogues were compared and rated for size and composition of group, social organization, preparedness for mission, duration of tour, types of tasks, physical and psychological isolation, personal motivation, perceived risk, and quality of habitat and life support conditions. One-hundred design recommendations concerning, sleep, clothing, exercise, medical support, personal hygiene, food preparation, group interaction, habitat aesthetics, outside communications, recreational opportunities, privacy and personal space, waste disposal, onboard training, simulation and task preparation, and behavioral and physiological requirements associated with a microgravity environment, are provided.

  20. BPM Analog front-end electronics based on the AD8307 log amplifier

    Science.gov (United States)

    Shurter, R. B.; Gilpatrick, J. D.; Power, J.

    2000-11-01

    Beam position monitor (BPM) signal-processing electronics utilizing the Analog Devices AD8307 logarithmic amplifier has been developed for the Low Energy Demonstration Accelerator (LEDA), part of the Accelerator Production of Tritium (APT) project at Los Alamos. The low-pass filtered 350 MHz fundamental signal from each of the four microstrip electrodes in a BPM is "detected" by an AD8307 log amp, amplified and scaled to accommodate the 0 to +5 V input of an analog-to-digital (A/D) converter. The resultant four digitized signals represent a linear power relationship to the electrode signals, which are in turn related to beam current and position. As the AD8307 has a potential dynamic range of approximately 92 dB, much attention must be given to noise reduction, sources of which can be digital signals on the same board, power supplies, inter-channel coupling, stray RF and others. This paper will describe the operational experience of this particular analog front-end electronic circuit design.

  1. BPM ANALOG FRONT-END ELECTRONICS BASED ON THE AD8307 LOG AMPLIFIER

    Energy Technology Data Exchange (ETDEWEB)

    R. SHURTER; ET AL

    2000-06-01

    Beam position monitor (BPM) signal-processing electronics utilizing the Analog Devices AD8307 logarithmic amplifier has been developed for the Low Energy Demonstration Accelerator (LEDA), part of the Accelerator Production of Tritium (APT) project at Los Alamos. The low-pass filtered 350 MHz fundamental signal from each of the four microstrip electrodes in a BPM is ''detected'' by an AD8307 log amp, amplified and scaled to accommodate the 0 to +5V input of an analog-to-digital (A/D) converter. The resultant four digitized signals represent a linear power relationship to the electrode signals, which are in turn related to beam current and position. As the AD8307 has a potential dynamic range of approximately 92 dB, much attention must be given to noise reduction, sources of which can be digital signals on the same board, power supplies, inter-channel coupling, stray RF and others. This paper will describe the operational experience of this particular analog front-end electronic circuit design.

  2. A Large Span Crossbeam Vibration Frequencies Analysis Based on an Analogous Beam Method

    Directory of Open Access Journals (Sweden)

    Zhifeng Liu

    2013-01-01

    Full Text Available The novel method of an analogous beam is studied, which the flexural rigidity and mass per unit length correspond was described as the reciprocal of the mass per unit and the reciprocal of the flexural rigidity of the beam. It is shown that both beams possess the same natural frequencies of flexural vibration. In order to approximate calculation of these frequencies, the continuously distributed mass of the original beam is substituted for a number of concentrated masses. The analogous beam then becomes a chain of rigid links connected by pins and equipped with springs restraining the relative rotation of adjacent links. The equations of motion for the analogous beam can be solved by a procedure which consists of assuming a value for the natural frequency and calculating the deflections successively from one end of the beam to the other. Under normal circumstances, there will be a certain error, and one boundary condition will not be satisfied. The procedure is repeated with different values of the frequency until the error is removed. The method is illustrated by an example of a Crossbeam for which the fundamental frequency is found.

  3. Analysis of the resolution-bandwidth-noise trade-off in wavelength-based photonic analog-to-digital converters.

    Science.gov (United States)

    Stigwall, Johan; Galt, Sheila

    2006-06-20

    The performance of wavelength-based photonic analog-to-digital converters (ADCs) is theoretically analyzed in terms of resolution and bandwidth as well as of noise tolerance. The analysis applies to any photonic ADC in which the analog input signal is converted into the wavelength of an optical carrier, but special emphasis is put on the spectrometerlike setup in which the wavelength is mapped to a spatial spot position. The binary output signals are then retrieved by an array of fan-out diffractive optical elements that redirect the beam onto the correct detectors. In particular, the case when the input signal controls the wavelength directly such that it will chirp in frequency during each sampling pulse or interval is studied. This chirping obviously broadens the spot on the diffractive optical element array; the effect of this broadening on noise tolerance and comparator accuracy is analytically analyzed, and accurate numerical calculations of the probability of error are presented.

  4. Inductive, Analogical, and Communicative Generalization

    Directory of Open Access Journals (Sweden)

    Adri Smaling

    2003-03-01

    Full Text Available Three forms of inductive generalization - statistical generalization, variation-based generalization and theory-carried generalization - are insufficient concerning case-to-case generalization, which is a form of analogical generalization. The quality of case-to-case generalization needs to be reinforced by setting up explicit analogical argumentation. To evaluate analogical argumentation six criteria are discussed. Good analogical reasoning is an indispensable support to forms of communicative generalization - receptive and responsive (participative generalization — as well as exemplary generalization.

  5. Synthesis of MR-49, a deiodinated analog of tetraiodothyroacetic acid (tetrac), as a novel pro-angiogenesis modulator.

    Science.gov (United States)

    Rajabi, Mehdi; Sudha, Thangirala; Darwish, Noureldien H E; Davis, Paul J; Mousa, Shaker A

    2016-08-15

    The tyrosine-based hormones 3,3',5-triiodo-l-thyronine (l-T3) and l-thyroxine (l-T4) that are produced by the thyroid gland control metabolic functions. Iodothyronine deiodinase enzymes convert l-T4 to l-T3, the form of thyroid hormone critical to genomic actions within cells and regulation of metabolism, and to reverse-l-T3, a hormone isoform that is largely inactive. We used tertiary amines in a study of deiodination based on derivatives of tetraiodothyroacetic acid (tetrac)-a naturally occurring derivative of l-T4-to mimic the action of the iodothyronine deiodinases and deiodination of the outer ring iodines. Deiodinated tetrac, MR-49, was found to be pro-angiogenic, with this activity exceeding that of l-T3 and l-T4 in a hemoglobin Matrigel® plug assay of angiogenesis. Tetrac is anti-angiogenic via several nongenomic pathways, and the present studies of MR-49 reveal the critical contribution of outer ring iodines to the angiogenic properties of thyroid hormone analogues, which may have utility as pro-angiogenic pharmaceuticals. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Cyclic pentapeptide analogs based on endomorphin-2 structure: cyclization studies using liquid chromatography combined with on-line mass spectrometry and tandem mass spectrometry.

    Science.gov (United States)

    Piekielna, Justyna; Kluczyk, Alicja; Perlikowska, Renata; Janecka, Anna

    2014-05-01

    The cyclization of linear analogs based on endomorphin-2 structure, Tyr/Dmt-d-Lys-Phe-Phe-Asp-NH2 and Tyr/Dmt-d-Cys-Phe-Phe-Cys-NH2 (where Dmt=2',6'-dimethyltyrosine), resulting in obtaining lactam or disulfide derivatives, was studied using liquid chromatography combined with on-line mass spectrometry (LC-MS) and tandem mass spectrometry (LC-MS/MS). In case of cyclization via an amide bond, the formation of the cyclic monomers, cyclic but not linear dimers and even traces of cyclic trimers was observed. Disulfide bridge containing peptides was obtained by the solid-phase synthesis of the linear sequences, followed by either in-solution or on-resin cyclization. In case of the in-solution cyclization, the expected cyclic monomers were the only products. When oxidation of the cysteine residues was performed when the peptides were still on the resin, cyclic monomer and two cyclodimers, parallel and antiparallel, were found. Digestion of the isolated cyclodimers with α-chymotrypsin allowed for their unambiguous identification. The comparison of the cyclic monomer/dimer ratios for analogs with Tyr versus Dmt in position 1 revealed that the presence of the exocyclic Dmt favored formation of the cyclic monomer, most likely due to the increased steric bulk of this amino acid side-chain as compared with Tyr.

  7. Boronic acid-based autoligation of nucleic acids

    DEFF Research Database (Denmark)

    Barbeyron, R.; Vasseur, J.-J.; Smietana, M.;

    2013-01-01

    Abstract: The development of synthetic systems displaying dynamic and adaptive characteristics is a formidable challenge with wide applications from biotechnology to therapeutics. Recently, we described a dynamic and programmable nucleic acid-based system relying on the formation of reversible...... boronate internucleosidic linkages. The DNA- or RNA-templated system comprises a 5′-ended boronic acid probe connecting a 3′-ended ribonucleosidic oligonucleotide partner. To explore the dominant factors that control the reversible linkage, we synthesized a series of 3′-end modified ribonucleotidic strands...

  8. Enhanced killing of breast cancer cells by a d-amino acid analog of the winter flounder-derived pleurocidin NRC-03.

    Science.gov (United States)

    Hilchie, Ashley L; Haney, Evan F; Pinto, Devanand M; Hancock, Robert E W; Hoskin, David W

    2015-12-01

    Cationic antimicrobial peptides (CAPs) defend against pathogens and, in some cases, exhibit potent anticancer activities. We previously reported that the pleurocidin NRC-03 causes lysis of breast cancer and multiple myeloma cells. NRC-03 also reduces the EC50 of other cytotoxic compounds and prevents tumor growth in vivo. However, the therapeutic utility of NRC-03 may be limited by its susceptibility to degradation by proteases. The goal of this study was to characterize the anticancer activities of a d-amino acid analog of NRC-03 ([D]-NRC-03) that was predicted to be resistant to proteolytic degradation. Unlike NRC-03, [D]-NRC-03 was not degraded by human serum or trypsin and, in comparison to NRC-03, showed increased killing of breast cancer cells, including multidrug-resistant cells; however, [D]-NRC-03 was somewhat more cytotoxic than NRC-03 for several types of normal cells. Importantly, [D]-NRC-03 was more effective than NRC-03 in vivo since 4-fold less peptide was required for an equivalent inhibitory effect on the growth of breast cancer cell xenografts in immune-deficient mice. These findings demonstrate that a d-amino acid analog of NRC-03 overcomes a major limitation to the therapeutic use of NRC-03, namely peptide stability. Further modification of [D]-NRC-03 is required to improve its selectivity for cancer cells.

  9. Analog earthquakes

    Energy Technology Data Exchange (ETDEWEB)

    Hofmann, R.B. [Center for Nuclear Waste Regulatory Analyses, San Antonio, TX (United States)

    1995-09-01

    Analogs are used to understand complex or poorly understood phenomena for which little data may be available at the actual repository site. Earthquakes are complex phenomena, and they can have a large number of effects on the natural system, as well as on engineered structures. Instrumental data close to the source of large earthquakes are rarely obtained. The rare events for which measurements are available may be used, with modfications, as analogs for potential large earthquakes at sites where no earthquake data are available. In the following, several examples of nuclear reactor and liquified natural gas facility siting are discussed. A potential use of analog earthquakes is proposed for a high-level nuclear waste (HLW) repository.

  10. Whole body acid-base modeling revisited.

    Science.gov (United States)

    Ring, Troels; Nielsen, Søren

    2017-04-01

    The textbook account of whole body acid-base balance in terms of endogenous acid production, renal net acid excretion, and gastrointestinal alkali absorption, which is the only comprehensive model around, has never been applied in clinical practice or been formally validated. To improve understanding of acid-base modeling, we managed to write up this conventional model as an expression solely on urine chemistry. Renal net acid excretion and endogenous acid production were already formulated in terms of urine chemistry, and we could from the literature also see gastrointestinal alkali absorption in terms of urine excretions. With a few assumptions it was possible to see that this expression of net acid balance was arithmetically identical to minus urine charge, whereby under the development of acidosis, urine was predicted to acquire a net negative charge. The literature already mentions unexplained negative urine charges so we scrutinized a series of seminal papers and confirmed empirically the theoretical prediction that observed urine charge did acquire negative charge as acidosis developed. Hence, we can conclude that the conventional model is problematic since it predicts what is physiologically impossible. Therefore, we need a new model for whole body acid-base balance, which does not have impossible implications. Furthermore, new experimental studies are needed to account for charge imbalance in urine under development of acidosis.

  11. Acid-base disorders: learning the basics.

    Science.gov (United States)

    Ayers, Phil; Dixon, Carman; Mays, Andrew

    2015-02-01

    Nutrition support practitioners should be confident in their ability to recognize and treat various metabolic and respiratory disorders encountered in daily practice. A clinician's comprehension of the underlying physiologic processes and/or exogenous causes that occur during acid-base disorders is essential when making therapeutic decisions regarding fluids, parenteral nutrition, and electrolyte management. This invited review will discuss basic metabolic and respiratory disorders while briefly addressing mixed acid-base disorders. © 2014 American Society for Parenteral and Enteral Nutrition.

  12. Graph-Based Symbolic Technique and Its Application in the Frequency Response Bound Analysis of Analog Integrated Circuits

    Directory of Open Access Journals (Sweden)

    E. Tlelo-Cuautle

    2014-01-01

    Full Text Available A new graph-based symbolic technique (GBST for deriving exact analytical expressions like the transfer function H(s of an analog integrated circuit (IC, is introduced herein. The derived H(s of a given analog IC is used to compute the frequency response bounds (maximum and minimum associated to the magnitude and phase of H(s, subject to some ranges of process variational parameters, and by performing nonlinear constrained optimization. Our simulations demonstrate the usefulness of the new GBST for deriving the exact symbolic expression for H(s, and the last section highlights the good agreement between the frequency response bounds computed by our variational analysis approach versus traditional Monte Carlo simulations. As a conclusion, performing variational analysis using our proposed GBST for computing the frequency response bounds of analog ICs, shows a gain in computing time of 100x for a differential circuit topology and 50x for a 3-stage amplifier, compared to traditional Monte Carlo simulations.

  13. Novel CCII-based Field Programmable Analog Array and its Application to a Sixth-Order Butterworth LPF

    Directory of Open Access Journals (Sweden)

    S. A. Mahmoud

    2013-06-01

    Full Text Available In this paper, a field programmable analog array (FPAA is proposed. The proposed FPAA consists of seven configurable analog blocks (CABs arranged in a hexagonal lattice such that the CABs are directly connected to each other. This structure improves the overall frequency response of the chip by decreasing the parasitic capacitances in the signal path. The CABS of the FPAA is based on a novel fully differential digitally programmable current conveyor (DPCCII. The programmability of the DPCCII is achieved using digitally controlled three-bit MOS ladder current division network. No extra biasing circuit is required to generate specific analog control voltage signals. The DPCCII has constant standby power consumption, offset voltage, bandwidth and harmonic distortions over all its programming range. A sixth-order Butterworth tunable LPF suitable for WLAN/WiMAX receivers is realized on the proposed FPAA. The filter power consumption is 5.4mW from 1V supply; it’s cutoff frequency is tuned from 5.2 MHz to 16.9 MHz. All the circuits are realized using 90nm CMOS technology from TSMC. All simulations are carried out using Cadence.

  14. Comparison of two analog-based downscaling methods for regional reference evapotranspiration forecasts

    Science.gov (United States)

    Tian, Di; Martinez, Christopher J.

    2012-12-01

    SummaryThe objective of this study was to compare the performance of natural analog (NA) and constructed analog (CA) methods to produce both probabilistic and deterministic downscaled daily reference evapotranspiration (ETo) forecasts in the southeastern United States. The 1-15 day, 15-member ETo forecasts were produced from 1979 to 2009 using the Penman-Monteith equation and a forecast analog approach with a combination of the Global Forecast System (GFS) reforecasts and NCEP-DOE Reanalysis 2 climatology, and were downscaled using the North American Regional Reanalysis (NARR). The Pearson correlation coefficient (R), mean squared error skill score (MSESS), and Bias were used to evaluate the skill of downscaled deterministic forecasts. The Linear Error in Probability Space (LEPS) skill score, Brier Skill Score (BSS), relative operating characteristic, and reliability diagrams were used to evaluate the skill of downscaled probabilistic forecasts. Overall, CA showed slightly higher skill than NA in terms of the metrics for deterministic forecasts, while for probabilistic forecasts NA showed higher skill than CA regarding the BSS in five categories (terciles, and 10th and 90th percentiles) and lower skill than CA regarding the LEPS skill score. Both CA and NA produced skillful deterministic results in the first 3 lead days, while the skill was higher for CA than for NA. Probabilistic NA forecasts exhibited higher resolution and reliability than CA, likely due to a larger ensemble size. Forecasts by both methods showed the lowest skill in the Florida peninsula and in mountainous areas, likely due to the fact that these features were not well-resolved in the model forecast.

  15. Slow-light plasmonic metamaterial based on dressed-state analog of electromagnetically-induced transparency

    CERN Document Server

    Raza, Søren

    2015-01-01

    We consider a simple configuration for realizing one-dimensional slow-light metamaterials with large bandwidth-delay products using stub-shaped Fabry-Perot resonators as building blocks. Each metaatom gives rise to large group indices due to a classical analog of the dressed-state picture of electromagnetically-induced transparency. By connecting up to eight metaatoms, we find bandwidth-delay products over unity and group indices approaching 100. Our approach is quite general and can be applied to any type of Fabry-Perot resonators and tuned to different operating wavelengths.

  16. Theoretical models of pentamidine analogs activity based on their DNA minor groove complexes.

    Science.gov (United States)

    Zołek, Teresa; Maciejewska, Dorota

    2010-05-01

    The B-DNA binding property of pentamidine analogs was analyzed employing molecular dynamic simulations and UV-vis absorption spectroscopy. Their AATT and ATAT sequence preferences were also examined. In theoretical energy computations, we considered two solvation models: the implicit model I, where the solvent is characterized by a dielectric constant and the explicit model E, where water molecules are treated as discrete entities. The binding energy correlates well with the increase of melting temperature of the 5'-d(CGCGAATTCGCG)(2)-3' and 5'-d(CGCGATATCGCG)(2)-3' dodecamers after complexation with ligands (DeltaTm), and deduced models predicted adequately the DNA affinities of the studied diamidines.

  17. A Direct, Biomass-Based Synthesis of Benzoic Acid: Formic Acid-Mediated Deoxygenation of the Glucose-Derived Materials Quinic Acid and Shikimic Acid

    Energy Technology Data Exchange (ETDEWEB)

    Arceo, Elena; Ellman, Jonathan; Bergman, Robert

    2010-05-03

    An alternative biomass-based route to benzoic acid from the renewable starting materials quinic acid and shikimic acid is described. Benzoic acid is obtained selectively using a highly efficient, one-step formic acid-mediated deoxygenation method.

  18. All digital monolithic scanning readout based on Sigma-Delta analog to digital conversion

    Science.gov (United States)

    Mandl, William; Rutschow, Carl

    1992-07-01

    It is generally accepted that sensor systems can benefit from some form of on-focal-plane A/D conversion in terms of overall system noise improvement. The issue of whether or not the Delta-Sigma modulation process can be applied to the development of an approach using conventional A/D converters or cryogenic circuit materials is addressed from the standpoint of the scanning focal plane. Each pixel row of the scanning sensor is treated as a continuous analog signal source with a fixed signal bandwidth. By allocating a Delta-Sigma converter per sensor pixel row, theory predicts the oversample rate required to achieve the designed conversion resolution. The Delta-Sigma consists of two major parts. The modulator, which samples the analog input and develops a corresponding digital bit stream, and the digital signal processor, which compresses the bit stream into the Nyquist rate multibit codes and performs noise filtering, are described. Only the modulator needs to be on the focal plane since its output is digital. This reduces the development problem to one of fitting the modulator only into the allocated space and power budget per sensor.

  19. Novel acridine-based N-acyl-homoserine lactone analogs induce endoreduplication in the human oral squamous carcinoma cell line SAS.

    Science.gov (United States)

    Chai, Hongbo; Hazawa, Masaharu; Hosokawa, Yoichiro; Igarashi, Jun; Suga, Hiroaki; Kashiwakura, Ikuo

    2012-01-01

    The cytotoxicity of novel acridine-based N-acyl-homoserine lactone (AHL) analogs was investigated on the human oral squamous carcinoma cell line SAS. One analog induced G2/M phase arrest at 5.3-10.6 µM and induced polyploidy at a higher dose (21.2 µM). Importantly, treatment of SAS cells with a combination of the AHL analog and the Jun N-terminal kinase (JNK) inhibitor, SP600125, prevented mitosis and induced polyploidy. The AHL analog synergized with X-irradiation to inhibit clonogenic survival of SAS cells; however, its radiosensitizing effects were relative to not X-irradiation-induced apoptosis but mitotic failure following enhanced expression of Aurora A and B. These results suggest that the active AHL analog showed growth-suppressive and radiosensitizing effects, which involve polyploidy followed by G2/M accumulation and atypical cell death in the SAS cell line.

  20. A Mars Analog for Wet-Based Glacial Alteration of Volcanic Terrains: Thermal Infrared Remote Sensing at Three Sisters, Oregon, U.S.A.

    Science.gov (United States)

    Rutledge, A. M.; Scudder, N. A.; Horgan, B.; Rampe, E. B.

    2016-09-01

    This study characterizes wet-based glacial weathering products at a volcanic Mars analog site using thermal infrared remote sensing. Decorrelation stretches are used to examine the geographic relationships between compositional units.

  1. Challenges in Analogical Reasoning

    CERN Document Server

    Lin, Shih-Yin

    2016-01-01

    Learning physics requires understanding the applicability of fundamental principles in a variety of contexts that share deep features. One way to help students learn physics is via analogical reasoning. Students can be taught to make an analogy between situations that are more familiar or easier to understand and another situation where the same physics principle is involved but that is more difficult to handle. Here, we examine introductory physics students' ability to use analogies in solving problems involving Newton's second law. Students enrolled in an algebra-based introductory physics course were given a solved problem involving tension in a rope and were then asked to solve another problem for which the physics is very similar but involved a frictional force. They were asked to point out the similarities between the two problems and then use the analogy to solve the friction problem.

  2. Optical Analog-to-digital Conversion Scheme Based on Tunable Fabry-Perot Resonator

    Institute of Scientific and Technical Information of China (English)

    LI Zheng

    2007-01-01

    Proposed is an interference type of optical analog-to-digital conversion(ADC). The refractive index of Fabry-Perot cavity changes with different voltages. The Fabry-Perot resonator converts electronic intensity into light wavelength through selecting lights of different wavelengthes. The parameters of the scheme are acquired with the transmission matrix of optical element and the time of steady-state light field. The maximum sampling speedes of 4-bit, 6-bit, 7-bit, 8-bit and 9-bit(ADC) are 1.695×1010 count/s, 4.33×109 count/s, 2.38×109 count/s, 1.24×109 count/s and 5.9×108 count/s, respectively.

  3. A Sub Threshold Source Coupled Logic Based Design of Low Power CMOS Analog Multiplexer

    Directory of Open Access Journals (Sweden)

    G.Deepika

    2014-11-01

    Full Text Available A novel approach for designing Ultra Low Power and wide dynamic range circuit for multiplexing analog signals is presented. The design operates in weak inversion (Sub threshold region and uses Source - Coupled Logic ( SCL circuit. The bias current of the SCL gates is varied to scale down linearly the power consumption and the operating frequency. The multiplexer design employs CMOS transistors as transmission gate with dynamic threshold voltage. The design exhibits low power dissipation, high dynamic range and good linearity. The design was implemented in 180 nm technology and was operated at a supply voltage of 400 mV with a bias current ranging in the order of few Pico-amperes. The ON and OFF resistance of the transmission gate achieved were 27 ohms and 10 M ohms respectively. The power dissipation achieved is around 0.79 µW for a dynamic range of 1µV to 0.4 V.

  4. Automatic parametric fault detection in complex analog systems based on a method of minimum node selection

    Directory of Open Access Journals (Sweden)

    Bilski Adrian

    2016-09-01

    Full Text Available The aim of this paper is to introduce a strategy to find a minimal set of test nodes for diagnostics of complex analog systems with single parametric faults using the support vector machine (SVM classifier as a fault locator. The results of diagnostics of a video amplifier and a low-pass filter using tabu search along with genetic algorithms (GAs as node selectors in conjunction with the SVM fault classifier are presented. General principles of the diagnostic procedure are first introduced, and then the proposed approach is discussed in detail. Diagnostic results confirm the usefulness of the method and its computational requirements. Conclusions on its wider applicability are provided as well.

  5. Alternate source term models for Yucca Mountain performance assessment based on natural analog data and secondary mineral solubility

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, W.M.; Codell, R.B.

    1999-07-01

    Performance assessment calculations for the proposed high level radioactive waste repository at Yucca Mountain, Nevada, were conducted using the Nuclear Regulatory Commission Total-System Performance Assessment (TPA 3.2) code to test conceptual models and parameter values for the source term based on data from the Pena Blanca, Mexico, natural analog site and based on a model for coprecipitation and solubility of secondary schoepite. In previous studies the value for the maximum constant oxidative alteration rate of uraninite at the Nopal I uranium body at Pena Blanca was estimated. Scaling this rate to the mass of uranium for the proposed Yucca Mountain repository yields an oxidative alteration rate of 22 kg/y, which was assumed to be an upper limit on the release rate from the proposed repository. A second model was developed assuming releases of radionuclides are based on the solubility of secondary schoepite as a function of temperature and solution chemistry. Releases of uranium are given by the product of uranium concentrations at equilibrium with schoepite and the flow of water through the waste packages. For both models, radionuclides other than uranium and those in the cladding and gap fraction were modeled to be released at a rate proportional to the uranium release rate, with additional elemental solubility limits applied. Performance assessment results using the Pena Blanca oxidation rate and schoepite solubility models for Yucca Mountain were compared to the TPA 3.2 base case model, in which release was based on laboratory studies of spent fuel dissolution, cladding and gap release, and solubility limits. Doses calculated using the release rate based on natural analog data and the schoepite solubility models were smaller than doses generated using the base case model. These results provide a degree of confidence in safety predictions using the base case model and an indication of how conservatism in the base case model may be reduced in future analyses.

  6. Multiple Propofol-binding Sites in a γ-Aminobutyric Acid Type A Receptor (GABAAR) Identified Using a Photoreactive Propofol Analog*♦

    Science.gov (United States)

    Jayakar, Selwyn S.; Zhou, Xiaojuan; Chiara, David C.; Dostalova, Zuzana; Savechenkov, Pavel Y.; Bruzik, Karol S.; Dailey, William P.; Miller, Keith W.; Eckenhoff, Roderic G.; Cohen, Jonathan B.

    2014-01-01

    Propofol acts as a positive allosteric modulator of γ-aminobutyric acid type A receptors (GABAARs), an interaction necessary for its anesthetic potency in vivo as a general anesthetic. Identifying the location of propofol-binding sites is necessary to understand its mechanism of GABAAR modulation. [3H]2-(3-Methyl-3H-diaziren-3-yl)ethyl 1-(phenylethyl)-1H-imidazole-5-carboxylate (azietomidate) and R-[3H]5-allyl-1-methyl-5-(m-trifluoromethyl-diazirynylphenyl)barbituric acid (mTFD-MPAB), photoreactive analogs of 2-ethyl 1-(phenylethyl)-1H-imidazole-5-carboxylate (etomidate) and mephobarbital, respectively, have identified two homologous but pharmacologically distinct classes of intersubunit-binding sites for general anesthetics in the GABAAR transmembrane domain. Here, we use a photoreactive analog of propofol (2-isopropyl-5-[3-(trifluoromethyl)-3H-diazirin-3-yl]phenol ([3H]AziPm)) to identify propofol-binding sites in heterologously expressed human α1β3 GABAARs. Propofol, AziPm, etomidate, and R-mTFD-MPAB each inhibited [3H]AziPm photoincorporation into GABAAR subunits maximally by ∼50%. When the amino acids photolabeled by [3H]AziPm were identified by protein microsequencing, we found propofol-inhibitable photolabeling of amino acids in the β3-α1 subunit interface (β3Met-286 in β3M3 and α1Met-236 in α1M1), previously photolabeled by [3H]azietomidate, and α1Ile-239, located one helical turn below α1Met-236. There was also propofol-inhibitable [3H]AziPm photolabeling of β3Met-227 in βM1, the amino acid in the α1-β3 subunit interface photolabeled by R-[3H]mTFD-MPAB. The propofol-inhibitable [3H]AziPm photolabeling in the GABAAR β3 subunit in conjunction with the concentration dependence of inhibition of that photolabeling by etomidate or R-mTFD-MPAB also establish that each anesthetic binds to the homologous site at the β3-β3 subunit interface. These results establish that AziPm as well as propofol bind to the homologous intersubunit sites in the

  7. Radiolysis of Amino Acids by Heavy and Energetic Cosmic Ray Analogs in Simulated Space Environments: $\\alpha$-Glycine Zwitterion Form

    CERN Document Server

    Portugal, Williamary; Boduch, Philippe; Rothard, Hermann; Andrade, Diana P P

    2014-01-01

    In this work, we studied the stability of the glycine molecule in the crystalline zwitterion form, known as {\\alpha}-glycine ($^{+}$NH$_{3}$CH$_{2}$COO$^{-}$) under action of heavy cosmic ray analogs. The experiments were conducted in a high vacuum chamber at heavy ions accelerator GANIL, in Caen, France. The samples were bombarded at two temperatures (14 K and 300 K) by $^{58}$Ni$^{11+}$ ions of 46 MeV until the final fluence of $10^{13}$ ions cm$^{-2}$. The chemical evolution of the sample was evaluated in-situ using Fourrier Transformed Infrared (FTIR) spectrometer. The bombardment at 14 K produced several daughter species such as OCN$^-$, CO, CO$_2$, and CN$^-$. The results also suggest the appearing of peptide bonds during irradiation but this must be confirmed by further experiments. The halflives of glycine in Interstellar Medium were estimated to be 7.8 $\\times 10^3$ years (300 K) and 2.8 $\\times 10^3$ years (14 K). In the Solar System the values were 8.4 $\\times 10^2$ years (300 K) and 3.6 $\\times 10...

  8. Design of A 5-Bit Fully Parallel Analog to Digital Converter Using Common Gate Differrential Mos Pair-Based Comparator

    Science.gov (United States)

    Aytar, Oktay

    2015-09-01

    This paper presents a novel comparator structure based on the common gate differential MOS pair. The proposed comparator has been applied to fully parallel analog to digital converter (A/D converter). Furthermore, this article presents 5 bit fully parallel A/D Converter design using the cadence IC5141 design platform and NCSU(North Carolina State University) design kit with 0.18 μm CMOS technology library. The proposed fully parallel A/D converter consist of resistor array block, comparator block, 1-n decoder block and programmable logic array. The 1-n decoder block includes latch block and thermometer code circuit that is implemented using transmission gate based multiplexer circuit. Thus, sampling frequency and analog bandwidth are increased. The INL and DNL of the proposed fully parallel A/D converter are (0/ + 0.63) LSB and (-0.26/ + 0.31) LSB at a sampling frequency of 5 GS/s with an input signal of 50 MHz, respectively. The proposed fully parallel A/D Converter consumes 340 mW from 1.8 V supply.

  9. Acid-base balance in heart failure.

    Science.gov (United States)

    Frangiosa, A; De Santo, L S; Anastasio, P; De Santo, N G

    2006-01-01

    In end-stage heart failure, various acid-base disorders can be discovered due to the renal loss of hydrogen ions and hydrogen ion movements into cells, the reduction of the effective circulating volume, hypoxemia and renal failure. This justifies the occurrence of metabolic alkalosis, metabolic acidosis, respiratory alkalosis, as well as respiratory acidosis alone or in combination. Several studies have been published on the acid-base state in heart failure. In a 1951 study, Squires et al analyzed the distribution of body fluid in congestive heart failure by taking into consideration the abnormalities in serum electrolyte concentration and in acid-base equilibrium. A recent study by Milionis et al, analyzed 86 patients with congestive heart failure receiving conventional treatment; the majority of these patients exhibited hypokalemia, hyponatremia, hypocalcemia and hypophosphatemia. Disorders in acid-base balance were noted in 37.2% of patients. In a recent study, 70 patients with severe congestive heart failure before heart transplantation showed high-normal pH, slightly reduced pCO 2 and a slight loss of hydrogen ions. After heart transplantation, stability of blood pH and hydrogen ion concentrations was found. In contrast, bicarbonate and pCO 2 increased significantly. The data led us to formulate the diagnosis of a mixed acid-base disorder that includes respiratory alkalosis and metabolic alkalosis before heart transplantation. In heart failure, the presence of acid-base imbalance associated with the activation of mechanisms that lead to salt and water retention reveals evidence concerning the pivotal role of the kidney in determining the outcome of these patients.

  10. Topology of RNA-protein nucleobase-amino acid π-π interactions and comparison to analogous DNA-protein π-π contacts.

    Science.gov (United States)

    Wilson, Katie A; Holland, Devany J; Wetmore, Stacey D

    2016-05-01

    The present work analyzed 120 high-resolution X-ray crystal structures and identified 335 RNA-protein π-interactions (154 nonredundant) between a nucleobase and aromatic (W, H, F, or Y) or acyclic (R, E, or D) π-containing amino acid. Each contact was critically analyzed (including using a visual inspection protocol) to determine the most prevalent composition, structure, and strength of π-interactions at RNA-protein interfaces. These contacts most commonly involve F and U, with U:F interactions comprising one-fifth of the total number of contacts found. Furthermore, the RNA and protein π-systems adopt many different relative orientations, although there is a preference for more parallel (stacked) arrangements. Due to the variation in structure, the strength of the intermolecular forces between the RNA and protein components (as determined from accurate quantum chemical calculations) exhibits a significant range, with most of the contacts providing significant stability to the associated RNA-protein complex (up to -65 kJ mol(-1)). Comparison to the analogous DNA-protein π-interactions emphasizes differences in RNA- and DNA-protein π-interactions at the molecular level, including the greater abundance of RNA contacts and the involvement of different nucleobase/amino acid residues. Overall, our results provide a clearer picture of the molecular basis of nucleic acid-protein binding and underscore the important role of these contacts in biology, including the significant contribution of π-π interactions to the stability of nucleic acid-protein complexes. Nevertheless, more work is still needed in this area in order to further appreciate the properties and roles of RNA nucleobase-amino acid π-interactions in nature.

  11. Hypokalemic paralysis and acid-base balance

    Directory of Open Access Journals (Sweden)

    Ivo Casagranda

    2006-10-01

    Full Text Available Three cases of hypokalemic paralysis are reported, presenting to the Emergency Department. The first is a patient with a hypokalemic periodic paralysis with a normal acid-base status, the second is a case of hypokalemic flaccid paralysis of all extremities with a normal anion gap metabolic acidosis, the last is a patient with a hypokalemic distal paralysis of right upper arm with metabolic alkalosis. Afterwards some pathophysiologic principles and the clinical aspects of hypokalemia are discussed and an appropriate approach to do in Emergency Department, to identify the hypokalemic paralysis etiologies in the Emergency Department, is presented, beginning from the evaluation of acid-base status.

  12. A Sub Threshold Source Coupled Logic Based Design of Low Power CMOS Analog Multiplexer

    Directory of Open Access Journals (Sweden)

    G.Deepika

    2014-08-01

    Full Text Available A novel approach for designing Ultra Low Power and wide dynamic range circuit for multiplexing analog signals is presented. The design operates in weak i nversion (Sub threshold region and uses Source - Coupled Logic ( SCL circuit. The bias current of t he SCL gates is varied to scale down linearly the p ower consumption and the operating frequency. The multip lexer design employs CMOS transistors as transmission gate with dynamic threshold voltage. T he design exhibits low power dissipation, high dynamic range and good linearity. The design was im plemented in 180 nm technology and was operated at a supply voltage of 400 mV with a bias current rang ing in the order of few Pico-amperes. The ON and OFF resistance of the transmission gate achieved we re 27 ohms and 10 M ohms respectively. The power dissipation achieved is around 0.79 μ W for a dynami c range of 1μ V to 0.4 V.

  13. High-Precision CMOS Analog Computational Circuits Based on a New Linearly Tunable OTA

    Directory of Open Access Journals (Sweden)

    A. Naderi Saatlo

    2016-06-01

    Full Text Available Implementation of CMOS current-mode analog computational circuits are presented in this paper. A new Linearly Tunable OTA is employed in a modified structure as a basic building block for implementation of the circuits either linear or nonlinear functions. The proposed trans-conductance amplifier provides a constant Gm over a wide range of input voltage which allows the implementation of high precision computational circuits including square rooting, squaring, multiplication and division functions. Layout pattern of the proposed circuit confirms that the circuit can be implemented in 102μm*69μm active area. In order to verify the performance of the circuits, the post layout simulation results are presented through the use of HSPICE and Cadence with TSMC level 49 (BSIM3v3 parameters for 0.18 μm CMOS technology, where under supply voltage of 1.8 V, the maximum relative error of the circuits within 500 µA of input range is about 11 μA (2.2 % error and the THD remains as low as 1.2 % for the worst case. Moreover, the power dissipation of the complete structure is found to be 0.66 mW.

  14. Influence of Iron on Production of the Antibacterial Compound Tropodithietic Acid and Its Noninhibitory Analog in Phaeobacter inhibens

    OpenAIRE

    D'Alvise, Paul W.; Phippen, Christopher B. W.; Nielsen, Kristian F; Gram, Lone

    2016-01-01

    Tropodithietic acid (TDA) is an antibacterial compound produced by some Phaeobacter and Ruegeria spp. of the Roseobacter clade. TDA production is studied in marine broth or agar since antibacterial activity in other media is not observed. The purpose of this study was to determine how TDA production is influenced by substrate components. High concentrations of ferric citrate, as present in marine broth, or other iron sources were required for production of antibacterially active TDA. However,...

  15. Synthesis and biological evaluation of cholecystokinin analogs in which the Asp-Phe-NH2 moiety has been replaced by a 3-amino-7-phenylheptanoic acid or a 3-amino-6-(phenyloxy)hexanoic acid.

    Science.gov (United States)

    Amblard, M; Rodriguez, M; Lignon, M F; Galas, M C; Bernad, N; Artis-Noël, A M; Hauad, L; Laur, J; Califano, J C; Aumelas, A

    1993-10-01

    Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-2-phenylethyl ester (JMV180), an analog of the C-terminal octapeptide of cholecystokinin (CCK-8), shows interesting biological activities behaving as an agonist at the high-affinity CCK binding sites and as an antagonist at the low-affinity CCK binding sites in rat pancreatic acini. Although we did not observe any major hydrolysis of the ester bond of Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-2-phenylethyl ester in our in vitro studies, we were aware of a possible and rapid cleavage of this ester bond during in vivo studies. To improve the stability of Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-2-phenylethyl ester, we decided to synthesize analogs in which the ester bond would be replaced by a carba (CH2-CH2) linkage. We synthesized the 3-amino-7-phenylheptanoic acid (beta-homo-Aph) with the R configuration in order to mimic the Asp-2-phenylethyl ester moiety and the 3-amino-6-(phenyloxy)hexanoic acid (H-beta-homo-App-OH), an analog of H-beta-homo-Aph-OH in which a methylene group has been replaced by an oxygen. (R)-beta-Homo-Aph and (R)-H-beta-homo-App-OH were introduced in the CCK-8 sequence to produce Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-(R)-beta-homo-Aph-OH and Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-(R)-beta-homo-App-OH. Both compounds were able to recognize the CCK receptor on rat pancreatic acini (IC50 = 12 +/- 8 nM and 13 +/- 5 nM, respectively), on brain membranes (IC50 = 32 +/- 2 nM and 57 +/- 5 nM, respectively), and on Jurkat T cells (IC50 = 75 +/- 15 nM and 65 +/- 21 nM, respectively). Like Boc-Tyr(SO3H)-Nle-Gly-Trp-Nle-Asp-2-phenylethyl ester, both compounds produced maximal stimulation of amylase secretion (EC50 = 6 +/- 2 nM and 4 +/- 2 nM, respectively) with no decrease of the secretion at high concentration indicating that these compounds probably act as agonists at the high-affinity peripheral CCK-receptor and as antagonists at the low-affinity CCK-receptor. Replacing the tryptophan by a D-tryptophan in such analogs produced full CCK

  16. A Comparison between Physics-based and Polytropic MHD Models for Stellar Coronae and Stellar Winds of Solar Analogs

    Science.gov (United States)

    Cohen, O.

    2017-02-01

    The development of the Zeeman–Doppler Imaging (ZDI) technique has provided synoptic observations of surface magnetic fields of low-mass stars. This led the stellar astrophysics community to adopt modeling techniques that have been used in solar physics using solar magnetograms. However, many of these techniques have been neglected by the solar community due to their failure to reproduce solar observations. Nevertheless, some of these techniques are still used to simulate the coronae and winds of solar analogs. Here we present a comparative study between two MHD models for the solar corona and solar wind. The first type of model is a polytropic wind model, and the second is the physics-based AWSOM model. We show that while the AWSOM model consistently reproduces many solar observations, the polytropic model fails to reproduce many of them, and in the cases where it does, its solutions are unphysical. Our recommendation is that polytropic models, which are used to estimate mass-loss rates and other parameters of solar analogs, must first be calibrated with solar observations. Alternatively, these models can be calibrated with models that capture more detailed physics of the solar corona (such as the AWSOM model) and that can reproduce solar observations in a consistent manner. Without such a calibration, the results of the polytropic models cannot be validated, but they can be wrongly used by others.

  17. A Study of an Architecture Design Learning Process Based on Social Learning, Course Teaching, Interaction, and Analogical Thinking

    Directory of Open Access Journals (Sweden)

    Yun-Wu Wu

    2014-01-01

    Full Text Available The students in the vocational education of architecture design in Taiwan often face many learning obstacles, such as no problem solving ability and lack of creativity. Therefore, this study used a social learning model as a learning strategy in the architecture design learning process to solve related learning difficulties. Firstly, this study used cognitive development teaching activities and a learning process based on analogical thinking and analogical reasoning to build the social learning model. Secondly, the social learning model of this study was implemented in the teaching of a required course of architecture design for 120 freshmen in China University of Technology. The questionnaire survey results were then statically analyzed and compared to measure the differences in the students’ knowledge about architecture designs before and after the teaching in this study. In this study, the social learning model is proven helpful in inspiring the students’ creativity by converting new knowledge of architecture design into schemas and hence retaining the new knowledge for future application. The social learning model can be applied in the teaching of architecture design in other schools, while more research can be conducted in the future to further confirm its feasibility to promote effective learning.

  18. Performance investigation of InAs based dual electrode tunnel FET on the analog/RF platform

    Science.gov (United States)

    Anand, Sunny; Sarin, R. K.

    2016-09-01

    In this paper for the first time, InAs based doping-less Tunnel FET is proposed and investigated. This paper also demonstrates and discusses the impact of gate stacking (SiO2 + HfO2) with equivalent oxide thickness EOT = 0.8 for analog/RF performance. The charge plasma technique is used to form source/drain region on an intrinsic InAs body by selecting proper work function of metal electrode. The paper compares different combinations of gate stacking (SiO2 and HfO2) on the basis of different analog and RF parameters such as transconductance (gm), transconductance to drive current ratio (gm/ID), output conductance (gd), intrinsic gain (AV), total gate capacitance (Cgg) and unity-gain cutoff frequency (fT). The proposed device produces an ON state current of ION ∼6 mA along with ION/IOFF ∼1012, point subthreshold slope (SS ∼ 1.9 mV/dec), average subthreshold slope (AV-SS ∼ 14.2 mV/dec) and cut-off frequency in Terahertz. The focus of this work is to eliminate the fabrication issues and providing the enhanced performance compared to doped device.

  19. Fault Modeling and Testing for Analog Circuits in Complex Space Based on Supply Current and Output Voltage

    Directory of Open Access Journals (Sweden)

    Hongzhi Hu

    2015-01-01

    Full Text Available This paper deals with the modeling of fault for analog circuits. A two-dimensional (2D fault model is first proposed based on collaborative analysis of supply current and output voltage. This model is a family of circle loci on the complex plane, and it simplifies greatly the algorithms for test point selection and potential fault simulations, which are primary difficulties in fault diagnosis of analog circuits. Furthermore, in order to reduce the difficulty of fault location, an improved fault model in three-dimensional (3D complex space is proposed, which achieves a far better fault detection ratio (FDR against measurement error and parametric tolerance. To address the problem of fault masking in both 2D and 3D fault models, this paper proposes an effective design for testability (DFT method. By adding redundant bypassing-components in the circuit under test (CUT, this method achieves excellent fault isolation ratio (FIR in ambiguity group isolation. The efficacy of the proposed model and testing method is validated through experimental results provided in this paper.

  20. Fermented probiotic beverages based on acid whey

    Directory of Open Access Journals (Sweden)

    Katarzyna Skryplonek

    2015-12-01

    Full Text Available Background. Production of fermented probiotic beverages can be a good method for acid whey usage. The obtained products combine a high nutritional value of whey with health benefits claimed for probiotic bac- teria. The aim of the study was to define quality properties of beverages based on fresh acid whey and milk with addition of buttermilk powder or sweet whey powder. Material and methods. Samples were inoculated with two strains of commercial probiotic cultures: Lac- tobacillus acidophilus La-5 or Bifidobacterium animalis Bb-12. After fermentation, samples were stored at refrigerated conditions. After 1, 4, 7, 14 and 21 days sensory characteristics, hardness, acetaldehyde content, titratable acidity, pH acidity and count of bacteria cells were evaluated. Results. Throughout all storage period, the number of bacteria was higher than 8 log cfu/ml in the all sam- ples. Beverages with La-5 strain had higher hardness and acidity, whilst samples with Bb-12 contained more acetaldehyde. Samples with buttermilk powder had better sensory properties than with sweet whey powder. Conclusions. Obtained products made of acid whey combined with milk and fortified with buttermilk pow- der or sweet whey powder, are good medium for growth and survival of examined probiotic bacteria strains. The level of bacteria was sufficient to provide health benefits to consumers.

  1. The Effects of Spaceflight and a Spaceflight Analog on Neurocognitive Perfonnance: Extent, Longevity, and Neural Bases

    Science.gov (United States)

    Seidler, R. D.; Mulavara, A. P.; Koppelmans, V.; Erdeniz, B.; Kofman, I. S.; DeDios, Y. E.; Szecsy, D. L.; Riascos-Castaneda, R. F.; Wood, S. J.; Bloomberg, J. J.

    2014-01-01

    We are conducting ongoing experiments in which we are performing structural and functional magnetic resonance brain imaging to identify the relationships between changes in neurocognitive function and neural structural alterations following a six month International Space Station mission and following 70 days exposure to a spaceflight analog, head down tilt bedrest. Our central hypothesis is that measures of brain structure, function, and network integrity will change from pre to post intervention (spaceflight, bedrest). Moreover, we predict that these changes will correlate with indices of cognitive, sensory, and motor function in a neuroanatomically selective fashion. Our interdisciplinary approach utilizes cutting edge neuroimaging techniques and a broad ranging battery of sensory, motor, and cognitive assessments that will be conducted pre flight, during flight, and post flight to investigate potential neuroplastic and maladaptive brain changes in crewmembers following long-duration spaceflight. Success in this endeavor would 1) result in identification of the underlying neural mechanisms and operational risks of spaceflight-induced changes in behavior, and 2) identify whether a return to normative behavioral function following re-adaptation to Earth's gravitational environment is associated with a restitution of brain structure and function or instead is supported by substitution with compensatory brain processes. With the bedrest study, we will be able to determine the neural and neurocognitive effects of extended duration unloading, reduced sensory inputs, and increased cephalic fluid distribution. This will enable us to parse out the multiple mechanisms contributing to any spaceflight-induced neural structural and behavioral changes that we observe in the flight study. In this presentation I will discuss preliminary results from six participants who have undergone the bed rest protocol. These individuals show decrements in balance and functional mobility

  2. Glycine/Glycolic acid based copolymers

    NARCIS (Netherlands)

    in 't Veld, P.J.A.; in 't Veld, Peter J.A.; Shen, Zheng-Rong; Shen, Z.; Takens, Gijsbert A.J.; Takens, G.A.J.; Dijkstra, Pieter J.; Feijen, Jan

    1994-01-01

    Glycine/glycolic acid based biodegradable copolymers have been prepared by ring-opening homopolymerization of morpholine-2,5-dione, and ring-opening copolymerization of morpholine-2,5-dione and glycolide. The homopolymerization of morpholine-2,5-dione was carried out in the melt at 200°C for 3 min

  3. Jigsaw Cooperative Learning: Acid-Base Theories

    Science.gov (United States)

    Tarhan, Leman; Sesen, Burcin Acar

    2012-01-01

    This study focused on investigating the effectiveness of jigsaw cooperative learning instruction on first-year undergraduates' understanding of acid-base theories. Undergraduates' opinions about jigsaw cooperative learning instruction were also investigated. The participants of this study were 38 first-year undergraduates in chemistry education…

  4. The Magic Sign: Acids, Bases, and Indicators.

    Science.gov (United States)

    Phillips, Donald B.

    1986-01-01

    Presents an approach that is used to introduce elementary and junior high students to a series of activities that will provide concrete experiences with acids, bases, and indicators. Provides instructions and listings of needed solutions and materials for developing this "magic sign" device. Includes background information and several…

  5. Jigsaw Cooperative Learning: Acid-Base Theories

    Science.gov (United States)

    Tarhan, Leman; Sesen, Burcin Acar

    2012-01-01

    This study focused on investigating the effectiveness of jigsaw cooperative learning instruction on first-year undergraduates' understanding of acid-base theories. Undergraduates' opinions about jigsaw cooperative learning instruction were also investigated. The participants of this study were 38 first-year undergraduates in chemistry education…

  6. Glycine/Glycolic acid based copolymers

    NARCIS (Netherlands)

    Veld, in 't Peter J.A.; Shen, Zheng-Rong; Takens, Gijsbert A.J.; Dijkstra, Pieter J.; Feijen, Jan

    1994-01-01

    Glycine/glycolic acid based biodegradable copolymers have been prepared by ring-opening homopolymerization of morpholine-2,5-dione, and ring-opening copolymerization of morpholine-2,5-dione and glycolide. The homopolymerization of morpholine-2,5-dione was carried out in the melt at 200°C for 3 min u

  7. Application of palladium-catalyzed carboxyl anhydride-boronic acid cross coupling in the synthesis of novel bile acids analogs with modified side chains.

    Science.gov (United States)

    Mayorquín-Torres, Martha C; Flores-Álamo, Marcos; Iglesias-Arteaga, Martin A

    2015-09-01

    Palladium-catalyzed cross coupling of 4-methoxycarbonyl phenyboronic acid with acetylated bile acids in which the carboxyl functions was activated by formation of a mixed anhydride with pivalic anhydride afforded the cross coupled compounds, which were converted in novel side chain modified bile acids by one pot carbonyl reduction/removal of the protecting acetyl groups by Wolff-Kishner reduction. Unambiguous assignments of the NMR signals and crystal characterization of the heretofore unknown compounds are provided. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Cytocompatibility of novel extracellular matrix protein analogs of biodegradable polyester polymers derived from α-hydroxy amino acids.

    Science.gov (United States)

    Lecht, Shimon; Cohen-Arazi, Naomi; Cohen, Gadi; Ettinger, Keren; Momic, Tatjana; Kolitz, Michal; Naamneh, Majdi; Katzhendler, Jehoshua; Domb, Abraham J; Lazarovici, Philip; Lelkes, Peter I

    2014-01-01

    One of the challenges in regenerative medicine is the development of novel biodegradable materials to build scaffolds that will support multiple cell types for tissue engineering. Here we describe the preparation, characterization, and cytocompatibility of homo- and hetero-polyesters of α-hydroxy amino acid derivatives with or without lactic acid conjugation. The polymers were prepared by a direct condensation method and characterized using gel permeation chromatography, (1)H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, differential scanning calorimetry, optical activity, and solubility. The surface charge of the polymers was evaluated using zeta potential measurements. The polymers were coated onto glass cover slips followed by characterization using nano-surface profiler, thin film reflectometry, and atomic force microscopy (AFM). Their interaction with endothelial and neuronal cells was assessed using adhesion, proliferation, and differentiation assays. Of the characterized polymers, Poly-HOVal-LA, but not Poly-(D)HOPhe, significantly augmented nerve growth factor (NGF)-induced neuronal differentiation of the PC12 pheochromcytoma cells. In contrast, Poly-HOLeu increased by 20% the adhesion of endothelial cells, but did not affect PC12 cell differentiation. NGF-induced Erk1/2 phosphorylation in PC12 cells grown on the different polymers was similar to the effect observed for cells cultured on collagen type I. While no significant association could be established between charge and the differentiative/proliferative properties of the polymers, AFM analysis indicated augmentation of NGF-induced neuronal differentiation on smooth polymer surfaces. We conclude that overall selective cytocompatibility and bioactivity might render α-hydroxy amino acid polymers useful as extracellular matrix-mimicking materials for tissue engineering.

  9. A synthetic combinatorial strategy for developing a-conotoxin analogs as potent a7 nicotinic acetylcholine receptor antagonists

    DEFF Research Database (Denmark)

    Armishaw, Christopher J; Singh, Narender; Medina-Franco, Jose L;

    2010-01-01

    ) nAChR Fluo-4/Ca2+ assay, allowing amino acids that confer antagonistic activity for this receptor to be identified. A second series of individual alpha-conotoxin analogs based on the combinations of defined active amino acid residues from positional scan synthetic combinatorial library screening...... data were synthesized. Several analogs exhibited significantly improved antagonist activity for the alpha(7) nAChR compared with WT-ImI. Binding interactions between the analogs and the alpha(7) nAChR were explored using a homology model of the amino-terminal domain based on a crystal structure...... of an acetylcholine-binding protein. Finally, a third series of refined analogs was synthesized based on modeling studies, which led to several analogs with refined pharmacological properties. Of the 96 individual alpha-conotoxin analogs synthesized, three displayed > or =10-fold increases in antagonist potency...

  10. Relationship between Aldose reductase and superoxide dismutase inhibition capacities of indole-based analogs of melatonin derivatives

    Directory of Open Access Journals (Sweden)

    Daş-Evcimen N.

    2009-01-01

    Full Text Available Aldose reductase (AR has been implicated in the etiology of diabetic complications. Under diabetic conditions, the elevated vascular glucose level causes an increased flux through the polyol pathway, which induces functional and morphological changes associated with secondary diabetic complications such as cataract, neuropathy, and nephrop­athy. Oxidative stress, antioxidants, and the polyol pathway have recently been found to be linked in pathological states. A large number of structurally different compounds have been studied as potent in vitro AR inhibitors (ARIs. However, with few exceptions, these compounds did not show clinical benefit, and some even produced serious side effects. In view of the ARI activity of certain indole derivative compounds and antioxidant properties of melatonin, we investigated some indole-based analogs of melatonin derivatives. Antioxidant and ARI activity tests were applied to nine indole derivatives that are substituted at the third and fifth positions. Also, the relationship between ARI and antioxidant enzyme activity is discussed.

  11. Low power analog front-end electronics in deep submicrometer CMOS technology based on gain enhancement techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gómez-Galán, J.A., E-mail: jgalan@uhu.es [Dpto de Ingeniería Electrónica, Sist. Informáticos y Automática, Universidad de Huelva (Spain); Sánchez-Rodríguez, T.; Sánchez-Raya, M.; Martel, I. [Dpto de Ingeniería Electrónica, Sist. Informáticos y Automática, Universidad de Huelva (Spain); López-Martín, A. [Dpto de Ingeniería Eléctrica y Electrónica, Universidad Pública de Navarra (Spain); Carvajal, R.G. [Dpto de Ingeniería Electrónica, Universidad de Sevilla (Spain); Ramírez-Angulo, J. [Klipsch School of Electrical Engineering, New Mexico State University (United States)

    2014-06-01

    This paper evaluates the design of front-end electronics in modern technologies to be used in a new generation of heavy ion detectors—HYDE (FAIR, Germany)—proposing novel architectures to achieve high gain in a low voltage environment. As conventional topologies of operational amplifiers in modern CMOS processes show limitations in terms of gain, novel approaches must be raised. The work addresses the design using transistors with channel length of no more than double the feature size and a supply voltage as low as 1.2 V. A front-end system has been fabricated in a 90 nm process including gain boosting techniques based on regulated cascode circuits. The analog channel has been optimized to match a detector capacitance of 5 pF and exhibits a good performance in terms of gain, speed, linearity and power consumption.

  12. Rover-Based Instrumentation and Scientific Investigations During the 2012 Analog Field Test on Mauna Kea Volcano, Hawaii

    Science.gov (United States)

    Graham, L. D.; Graff, T. G.

    2013-01-01

    Rover-based 2012 Moon and Mars Analog Mission Activities (MMAMA) were recently completed on Mauna Kea Volcano, Hawaii. Scientific investigations, scientific input, and operational constraints were tested in the context of existing project and protocols for the field activities designed to help NASA achieve the Vision for Space Exploration [1]. Several investigations were conducted by the rover mounted instruments to determine key geophysical and geochemical properties of the site, as well as capture the geological context of the area and the samples investigated. The rover traverse and associated science investigations were conducted over a three day period on the southeast flank of the Mauna Kea Volcano, Hawaii. The test area was at an elevation of 11,500 feet and is known as "Apollo Valley" (Fig. 1). Here we report the integration and operation of the rover-mounted instruments, as well as the scientific investigations that were conducted.

  13. Increased urinary excretion of analogs of Krebs cycle metabolites and arabinose in two brothers with autistic features.

    Science.gov (United States)

    Shaw, W; Kassen, E; Chaves, E

    1995-08-01

    A marked increase in analogs of Krebs cycle metabolites was found in the urine of two brothers with autistic features. These metabolites included citramalic, tartaric (3-OH-malic), and 3-oxoglutaric acids and compounds tentatively identified as a citric acid analog and partially identified as a phenylcarboxylic acid by the fragmentation pattern of the trimethylsilyl (TMS) derivatives of the compounds and mass shifts of the same compounds derivatized with perdeuterated N,O-bis(trimethylsilyl)trifluoroacetamide. The molecular mass of the TMS derivative of the tentatively identified citric acid analog was 596 Da, based on a finding of a significant M - 15 ion at m/z 581. The citric acid analog was excreted in quantities as high as 137 mmol/mol creatinine, based on the response factor of citric acid as a surrogate calibrator. A carbohydrate with a retention time and mass spectrum identical to arabinose was also found in high concentrations in the urine of these brothers.

  14. The first proton sponge-based amino acids: synthesis, acid-base properties and some reactivity.

    Science.gov (United States)

    Ozeryanskii, Valery A; Gorbacheva, Anastasia Yu; Pozharskii, Alexander F; Vlasenko, Marina P; Tereznikov, Alexander Yu; Chernov'yants, Margarita S

    2015-08-21

    The first hybrid base constructed from 1,8-bis(dimethylamino)naphthalene (proton sponge or DMAN) and glycine, N-methyl-N-(8-dimethylamino-1-naphthyl)aminoacetic acid, was synthesised in high yield and its hydrobromide was structurally characterised and used to determine the acid-base properties via potentiometric titration. It was found that the basic strength of the DMAN-glycine base (pKa = 11.57, H2O) is on the level of amidine amino acids like arginine and creatine and its structure, zwitterionic vs. neutral, based on the spectroscopic (IR, NMR, mass) and theoretical (DFT) approaches has a strong preference to the zwitterionic form. Unlike glycine, the DMAN-glycine zwitterion is N-chiral and is hydrolytically cleaved with the loss of glycolic acid on heating in DMSO. This reaction together with the mild decarboxylative conversion of proton sponge-based amino acids into 2,3-dihydroperimidinium salts under air-oxygen was monitored with the help of the DMAN-alanine amino acid. The newly devised amino acids are unique as they combine fluorescence, strongly basic and redox-active properties.

  15. Quantum Analog Computing

    Science.gov (United States)

    Zak, M.

    1998-01-01

    Quantum analog computing is based upon similarity between mathematical formalism of quantum mechanics and phenomena to be computed. It exploits a dynamical convergence of several competing phenomena to an attractor which can represent an externum of a function, an image, a solution to a system of ODE, or a stochastic process.

  16. Mineralogy of evaporite deposits on Mars: Constraints from laboratory, field, and remote measurements of analog terrestrial acid saline lakes

    Science.gov (United States)

    Bridges, N.; Núñez, J. I.; Seelos, F. P., IV; Hook, S. J.; Baldridge, A. M.; Thomson, B. J.

    2015-12-01

    Remote compositional data from imaging spectrometers such as CRISM, OMEGA, and TES, and high-resolution imagery from MOC, CTX, and HiRISE have provided invaluable information for improving our understanding of the composition and geologic history of the martian surface and identifying potential past and present habitable environments on Mars. Simulated CRISM spectra and summary parameter maps and HiRISE color images were generated using airborne hyperspectral data of two acid-saline lakes in Western Australia. These locations are applicable to Mars, as they contain a suite of clays, sulfates, and salts formed under variable pH and salinity - mineralogies similar to those observed in Noachian and Hesperian terrain. The remote datasets were used to make surface composition predictions which were then verified through field study and sample analysis. We find phyllosilicates intermixed with sulfates in sulfate-rich surfaces exhibit variable spectral responses, even for similar conditions and abundances seen in the field. Where sulfates, such as gypsum and alunite, are found, phyllosilicates are intermixed or reside beneath the surface yet are not always detected. This suggests that geologic complexities may mask phyllosilicate detection at or near the surface on Mars where only sulfates have so far been found.

  17. Modulated regeneration of acid-etched human tooth enamel by a functionalized dendrimer that is an analog of amelogenin.

    Science.gov (United States)

    Chen, Mei; Yang, Jiaojiao; Li, Jiyao; Liang, Kunneng; He, Libang; Lin, Zaifu; Chen, Xingyu; Ren, Xiaokang; Li, Jianshu

    2014-10-01

    In the bioinspired repair process of tooth enamel, it is important to simultaneously mimic the organic-matrix-induced biomineralization and increase the binding strength at the remineralization interface. In this work, a fourth-generation polyamidoamine dendrimer (PAMAM) is modified by dimethyl phosphate to obtain phosphate-terminated dendrimer (PAMAM-PO3H2) since it has a similar dimensional scale and peripheral functionalities to that of amelogenin, which plays important role in the natural development process of enamel. Its phosphate group has stronger affinity for calcium ion than carboxyl group and can simultaneously provide strong hydroxyapatite (HA)-binding capability. The MTT assay demonstrates the low cytotoxicity of PAMAM-PO3H2. Adsorption tests indicate that PAMAM-PO3H2 can be tightly adsorbed on the human tooth enamel. Scanning electron microscopy and X-ray diffraction are used to analyze the remineralization process. After being incubated in artificial saliva for 3weeks, there is a newly generated HA layer of 11.23μm thickness on the acid-etched tooth enamel treated by PAMAM-PO3H2, while the thickness for the carboxyl-terminated one (PAMAM-COOH) is only 6.02μm. PAMAM-PO3H2 can regulate the remineralization process to form ordered new crystals oriented along the Z-axis and produce an enamel prism-like structure that is similar to that of natural tooth enamel. The animal experiment also demonstrates that PAMAM-PO3H2 can induce significant HA regeneration in the oral cavity of rats. Thus PAMAM-PO3H2 shows great potential as a biomimetic restorative material for human tooth enamel.

  18. Biotinylation of a propargylated cyclic (3'-5') diguanylic acid and of its mono-6-thioated analog under "click" conditions.

    Science.gov (United States)

    Grajkowski, Andrzej; Cieślak, Jacek; Schindler, Christian; Beaucage, Serge L

    2013-03-01

    Commercial N(2)-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-2'-O-(propargyl)guanosine is converted to its 3'-O-levulinyl ester in a yield of 91%. The reaction of commercial N(2)-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-2'-O-tert-butyldimethylsilyl-3'-O-[(2-cyanoethyl)-N,N-diisopropylaminophosphinyl]guanosine with N(2)-isobutyryl-2'-O-propargyl-3'-O-(levulinyl)guanosine provides, after P(III) oxidation, 3'-/5'-deprotection, and purification, the 2'-O-propargylated guanylyl(3'-5')guanosine 2-cyanoethyl phosphate triester in a yield of 88%. Phosphitylation of this dinucleoside phosphate triester with 2-cyanoethyl tetraisopropylphosphordiamidite and 1H-tetrazole, followed by an in situ intramolecular cyclization, gives the propargylated cyclic dinucleoside phosphate triester, which is isolated in a yield of 40% after P(III) oxidation and purification. Complete removal of the nucleobases, phosphates, and 2'-O-tert-butyldimethylsilyl protecting groups leads to the desired propargylated c-di-GMP diester. Cycloaddition of a biotinylated azide with the propargylated c-di-GMP diester under click conditions provides the biotinylated c-di-GMP conjugate in an isolated yield of 62%. Replacement of the 6-oxo function of N(2)-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-3'-O-levulinyl-2'-O-(propargyl)guanosine with a 2-cyanoethylthio group is effected by treatment with 2,4,6-triisopropybenzenesulfonyl chloride and triethylamine to give a 6-(2,4,6-triisopropylbenzenesulfonic acid) ester intermediate. Reaction of this key intermediate with 3-mercaptoproprionitrile and triethylamine, followed by 5'-dedimethoxytritylation, affords the 6-(2-cyanoethylthio)guanosine derivative in a yield of 70%. The 5'-hydroxy function of this derivative is reacted with commercial N(2)-isobutyryl-5'-O-(4,4'-dimethoxytrityl)-2'-O-tert-butyldimethylsilyl-3'-O-[(2-cyanoethyl)-N,N-diisopropylaminophosphinyl]guanosine. The reaction product is then converted to the mono-6-thioated c-di- GMP biotinylated conjugate under

  19. Design of Butterworth analog filter based on Matlab%基于Matlab的巴特沃斯滤波器设计

    Institute of Scientific and Technical Information of China (English)

    王大伟; 贾荣丛; 王划一

    2012-01-01

    为了得到较纯净的真实信号,对巴特沃斯模拟滤波器的幅频特性、设计方法及设计步骤进行了研究,利用Matlab程序,设计了巴特沃斯模拟滤波器,给出了Matlab设计程序,并分析了巴特沃斯模拟滤波器的幅频特性.利用Matlab程序绘制了巴特沃斯模拟滤波器的幅频特性曲线,并利用Matlab实现了模拟滤波器原型到模拟低通、高通、带通、带阻滤波器的转换.由模拟滤波器原型设计模拟高通滤波器的实例说明了滤波器频率转换效果.%The paper described the amplitude-frequency characteristics, the design method and procedure of Butterworth analog filter to obtain real signal. Butterworth analog filter was designed based on Matlab. The paper presented the design procedure of the filter based on Matlab and analyzed the amplitude-frequency characteristics of Butterworth analog filter. Matlab program was used to draw the amplitude-frequency characteristic curve of Butterworth analog filter and realize the conversion from analog filter prototype to analog low-pass, high-pass, band-pass and band-stop filter. Through the design of analog filter prototype, high-pass filter simulation shows the effects of frequency conversion.

  20. Parametric estimation in the wave buoy analogy - an elaborated approach based on energy considerations

    DEFF Research Database (Denmark)

    Montazeri, Najmeh; Nielsen, Ulrik Dam

    2014-01-01

    the ship’s wave-induced responses based on different statistical inferences including parametric and non-parametric approaches. This paper considers a concept to improve the estimate obtained by the parametric method for sea state estimation. The idea is illustrated by an analysis made on full-scale...

  1. A comparison of acceptance- and control-based strategies for coping with food cravings: an analog study.

    Science.gov (United States)

    Forman, Evan M; Hoffman, Kimberly L; McGrath, Kathleen B; Herbert, James D; Brandsma, Lynn L; Lowe, Michael R

    2007-10-01

    The present study utilized an analog paradigm to investigate the effectiveness of two strategies for coping with food cravings, which was theorized to be critical to the maintenance of weight loss. Ninety-eight undergraduate students were given transparent boxes of chocolate Hershey's Kisses and instructed to keep the chocolates with them, but not to eat them, for 48 h. Before receiving the Kisses, participants were randomized to receive either (a) no intervention, (b) instruction in control-based coping strategies such as distraction and cognitive restructuring, or (c) instruction in acceptance-based strategies such as experiential acceptance and defusion techniques. Measures included the Power of Food Scale (PFS; a measure of psychological sensitivity to the food environment), self-report ratings of chocolate cravings and surreptitiously recorded chocolate consumption. Results suggested that the effect of the intervention depended on baseline PFS levels, such that acceptance-based strategies were associated with better outcomes (cravings, consumption) among those reporting the highest susceptibility to the presence of food, but greater cravings among those who scored lowest on the PFS. It was observed that craving self-report measures predicted chocolate consumption, and baseline PFS levels predicted both cravings and consumption. Results are discussed in terms of the implications for weight loss maintenance strategies.

  2. Superconductivity in SnO: a nonmagnetic analog to Fe-based superconductors?

    Science.gov (United States)

    Forthaus, M K; Sengupta, K; Heyer, O; Christensen, N E; Svane, A; Syassen, K; Khomskii, D I; Lorenz, T; Abd-Elmeguid, M M

    2010-10-08

    We discovered that under pressure SnO with α-PbO structure, the same structure as in many Fe-based superconductors, e.g., β-FeSe, undergoes a transition to a superconducting state for p≳6 GPa with a maximum Tc of 1.4 K at p=9.3 GPa. The pressure dependence of Tc reveals a domelike shape and superconductivity disappears for p≳16 GPa. It is further shown from band structure calculations that SnO under pressure exhibits a Fermi surface topology similar to that reported for some Fe-based superconductors and that the nesting between the hole and electron pockets correlates with the change of Tc as a function of pressure.

  3. Synthesis and structural characterization of some trisulfide analoges of thiouracil-based antithyroid drugs

    Science.gov (United States)

    Bhabak, Krishna P.; Bhowmick, Debasish

    2012-08-01

    Thiourea-based antithyroid drugs are effectively used for the treatment of hyperthyroidism. In this paper, we describe the synthesis of new trisulfides (11-12) from the commonly used thiourea-based antithyroid drugs such as 6-n-propyl-2-thiouracil (PTU) and 6-methyl-2-thiouracil (MTU) in the reaction with I2/KI system. Structural analysis by single crystal X-ray diffraction studies revealed the stabilization of trisulfides by a lactam-lactim tautomerism facilitating effective intramolecular as well as intermolecular non-covalent interactions. Although the structures of both trisulfides were found to be quite similar, a notable difference in the intermolecular interactions was observed between compounds 11 and 12 leading to different structural patterns. Structural stabilization of these trisulfides by tautomerism followed by intramolecular as well as intermolecular H-bonds makes these molecules as perfect examples in molecular recognition with self-complementary donor and acceptor units within a single molecule.

  4. Superconductivity in SnO: A Nonmagnetic Analog to Fe-Based Superconductors?

    DEFF Research Database (Denmark)

    Forthaus, M. K.; Sengupta, K.; Heyer, O.;

    2010-01-01

    We discovered that under pressure SnO with α-PbO structure, the same structure as in many Fe-based superconductors, e.g., β-FeSe, undergoes a transition to a superconducting state for p≳6  GPa with a maximum Tc of 1.4 K at p=9.3  GPa. The pressure dependence of Tc reveals a domelike shape...... and superconductivity disappears for p≳16  GPa. It is further shown from band structure calculations that SnO under pressure exhibits a Fermi surface topology similar to that reported for some Fe-based superconductors and that the nesting between the hole and electron pockets correlates with the change of Tc...

  5. A Loudness Function for Analog and Digital Sound Systems based on Equal Loudness Level Contours

    DEFF Research Database (Denmark)

    Nielsen, Sofus Birkedal

    2016-01-01

    A new and better loudness compensation has been designed based on the differences between the Equal Loudness Level Contours (ELLC) in ISO 226:2003. Sound productions are normally being mixed at a high mixing level (ML) but often played at lower listening level (LL) which mean that the perceived f...... solution is realized in a 16/32 bit fixed point DSP and could be implemented in any sound producing system....

  6. Analogy of strain energy density based bone-remodeling algorithm and structural topology optimization.

    Science.gov (United States)

    Jang, In Gwun; Kim, Il Yong; Kwak, Byung Ban

    2009-01-01

    In bone-remodeling studies, it is believed that the morphology of bone is affected by its internal mechanical loads. From the 1970s, high computing power enabled quantitative studies in the simulation of bone remodeling or bone adaptation. Among them, Huiskes et al. (1987, "Adaptive Bone Remodeling Theory Applied to Prosthetic Design Analysis," J. Biomech. Eng., 20, pp. 1135-1150) proposed a strain energy density based approach to bone remodeling and used the apparent density for the characterization of internal bone morphology. The fundamental idea was that bone density would increase when strain (or strain energy density) is higher than a certain value and bone resorption would occur when the strain (or strain energy density) quantities are lower than the threshold. Several advanced algorithms were developed based on these studies in an attempt to more accurately simulate physiological bone-remodeling processes. As another approach, topology optimization originally devised in structural optimization has been also used in the computational simulation of the bone-remodeling process. The topology optimization method systematically and iteratively distributes material in a design domain, determining an optimal structure that minimizes an objective function. In this paper, we compared two seemingly different approaches in different fields-the strain energy density based bone-remodeling algorithm (biomechanical approach) and the compliance based structural topology optimization method (mechanical approach)-in terms of mathematical formulations, numerical difficulties, and behavior of their numerical solutions. Two numerical case studies were conducted to demonstrate their similarity and difference, and then the solution convergences were discussed quantitatively.

  7. Determination of therapeutic γ-aminobutyric acid analogs in forensic whole blood by hydrophilic interaction liquid chromatography-electrospray tandem mass spectrometry.

    Science.gov (United States)

    Sørensen, Lambert K; Hasselstrøm, Jørgen B

    2014-05-01

    Vigabatrin, pregabalin, gabapentin and baclofen are γ-aminobutyric acid analogs that are used in the treatment of epileptic seizures (vigabatrin, pregabalin and gabapentin) and spasticity (baclofen). The intake of these drugs may induce adverse reactions and impair the ability of an individual to drive a vehicle. There have also been reports of cases of intoxication and fatalities from overdoses. For rapid and accurate quantification of these drugs in forensic cases, an ultraperformance liquid chromatography tandem mass spectrometry method using pneumatically assisted electrospray ionization has been developed. The technique has been validated on both ante- and postmortem human whole blood. The protein in the blood samples was removed by the addition of a mixture of methanol and acetonitrile, and the extract was ultrafiltered and diluted with acetonitrile. The separation was performed by hydrophilic interaction liquid chromatography. Calibration of the system was achieved through use of matrix-matched calibrants combined with isotope dilution. The lower limits of quantification were 0.02-0.04 mg/L, and the relative intra-laboratory reproducibility standard deviations were 89%. The trueness expressed as the relative bias of the test results was within ±7% at concentrations of 1-40 mg/L for vigabatrin, pregabalin and gabapentin and of 0.1-4 mg/L for baclofen.

  8. Regulation of the Contribution of Integrin to Cell Attachment on Poly(2-Methoxyethyl Acrylate (PMEA Analogous Polymers for Attachment-Based Cell Enrichment.

    Directory of Open Access Journals (Sweden)

    Takashi Hoshiba

    Full Text Available Cell enrichment is currently in high demand in medical engineering. We have reported that non-blood cells can attach to a blood-compatible poly(2-methoxyethyl acrylate (PMEA substrate through integrin-dependent and integrin-independent mechanisms because the PMEA substrate suppresses protein adsorption. Therefore, we assumed that PMEA analogous polymers can change the contribution of integrin to cell attachment through the regulation of protein adsorption. In the present study, we investigated protein adsorption, cell attachment profiles, and attachment mechanisms on PMEA analogous polymer substrates. Additionally, we demonstrated the possibility of attachment-based cell enrichment on PMEA analogous polymer substrates. HT-1080 and MDA-MB-231 cells started to attach to poly(butyl acrylate (PBA and poly(tetrahydrofurfuryl acrylate (PTHFA, on which proteins could adsorb well, within 1 h. HepG2 cells started to attach after 1 h. HT-1080, MDA-MB-231, and HepG2 cells started to attach within 30 min to PMEA, poly(2-(2-methoxyethoxy ethyl acrylate-co-butyl acrylate (30:70 mol%, PMe2A and poly(2-(2-methoxyethoxy ethoxy ethyl acrylate-co-butyl acrylate (30:70 mol%, PMe3A, which suppress protein adsorption. Moreover, the ratio of attached cells from a cell mixture can be changed on PMEA analogous polymers. These findings suggested that PMEA analogous polymers can be used for attachment-based cell enrichment.

  9. Are all analogies created equal? Prefrontal cortical functioning may predict types of analogical reasoning.

    Science.gov (United States)

    Chrysikou, Evangelia G; Thompson-Schill, Sharon L

    2010-06-01

    Abstract The proposed theory can account for analogies based on learned relationships between elements in the source and target domains. However, its explanatory power regarding the discovery of new relationships during analogical reasoning is limited. We offer an alternative perspective for the role of PFC in analogical thought that may better address different types of analogical mappings.

  10. Investigating Students' Reasoning about Acid-Base Reactions

    Science.gov (United States)

    Cooper, Melanie M.; Kouyoumdjian, Hovig; Underwood, Sonia M.

    2016-01-01

    Acid-base chemistry is central to a wide range of reactions. If students are able to understand how and why acid-base reactions occur, it should provide a basis for reasoning about a host of other reactions. Here, we report the development of a method to characterize student reasoning about acid-base reactions based on their description of…

  11. Single- and two-phase flow in microfluidic porous media analogs based on Voronoi tessellation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Mengjie [Colorado School of Mines, Golden; Xiao, Feng [Colorado School of Mines, Golden; Johnson-Paben, Rebecca [Colorado School of Mines, Golden; Retterer, Scott T [ORNL; Yin, Xiaolong [Colorado School of Mines, Golden; Neeves, Keith B [ORNL

    2012-01-01

    The objective of this study was to create a microfluidic model of complex porous media for studying single and multiphase flows. Most experimental porous media models consist of periodic geometries that lend themselves to comparison with well-developed theoretical predictions. However, most real porous media such as geological formations and biological tissues contain a degree of randomness and complexity that is not adequately represented in periodic geometries. To design an experimental tool to study these complex geometries, we created microfluidic models of random homogeneous and heterogeneous networks based on Voronoi tessellations. These networks consisted of approximately 600 grains separated by a highly connected network of channels with an overall porosity of 0.11 0.20. We found that introducing heterogeneities in the form of large cavities within the network changed the permeability in a way that cannot be predicted by the classical porosity-permeability relationship known as the Kozeny equation. The values of permeability found in experiments were in excellent agreement with those calculated from three-dimensional lattice Boltzmann simulations. In two-phase flow experiments of oil displacement with water we found that the surface energy of channel walls determined the pattern of water invasion, while the network topology determined the residual oil saturation. These results suggest that complex network topologies lead to fluid flow behavior that is difficult to predict based solely on porosity. The microfluidic models developed in this study using a novel geometry generation algorithm based on Voronoi tessellation are a new experimental tool for studying fluid and solute transport problems within complex porous media.

  12. Experimental comparison of different oscillation-based test techniques in an analog block

    Science.gov (United States)

    Suenaga, Kay; Picos, Rodrigo; Bota, Sebastia; Roca, Miquel; Garcia-Moreno, Eugeni

    2005-06-01

    This paper experimentally analyses the capabilities of an Oscillation-Based Test technique for diagnosis purposes. To evaluate the feasibility of this test strategy, the technique is applied to an Operational Transconductance Amplifier with fault injection capabilities. The application of this methodology has low impact on circuit performances. Voltage and current magnitude have been considered as test observables. The effects of catastrophic and parametric defects (bridges, opens and shorts) are analyzed in this work. Results show that by a right choice of the test observable, this technique provides high fault coverage levels even in the case of process variations.

  13. High-affinity DNA base analogs as supramolecular, nanoscale promoters of macroscopic adhesion.

    Science.gov (United States)

    Anderson, Cyrus A; Jones, Amanda R; Briggs, Ellen M; Novitsky, Eric J; Kuykendall, Darrell W; Sottos, Nancy R; Zimmerman, Steven C

    2013-05-15

    Adhesion phenomena are essential to many biological processes and to synthetic adhesives and manufactured coatings and composites. Supramolecular interactions are often implicated in various adhesion mechanisms. Recently, supramolecular building blocks, such as synthetic DNA base-pair mimics, have drawn attention in the context of molecular recognition, self-assembly, and supramolecular polymers. These reversible, hydrogen-bonding interactions have been studied extensively for their adhesive capabilities at the nano- and microscale, however, much less is known about their utility for practical adhesion in macroscopic systems. Herein, we report the preparation and evaluation of supramolecular coupling agents based on high-affinity, high-fidelity quadruple hydrogen-bonding units (e.g., DAN·DeUG, Kassoc = 10(8) M(-1) in chloroform). Macroscopic adhesion between polystyrene films and glass surfaces modified with 2,7-diamidonaphthyridine (DAN) and ureido-7-deazaguanine (DeUG) units was evaluated by mechanical testing. Structure-property relationships indicate that the designed supramolecular interaction at the nanoscale plays a key role in the observed macroscopic adhesive response. Experiments probing reversible adhesion or self-healing properties of bulk samples indicate that significant recovery of initial strength can be realized after failure but that the designed noncovalent interaction does not lead to healing during the process of adhesion loss.

  14. Polarization splitter based on a three waveguide directional coupler using quantum mechanical analogies

    Science.gov (United States)

    Aashna, Pragati; Thyagarajan, K.

    2017-06-01

    We propose a novel waveguide polarization splitter based on the optical analogue of two-photon Rabi oscillations and stimulated Raman adiabatic passage in a three waveguide directional coupler. Both these processes are borrowed from three level quantum mechanical atomic systems, in which an intermediate level is used to transfer the population from one state to another without any population occupation in the intermediate level. To show the practical feasibility of the device, simulations have been carried out on waveguides in lithium niobate and we show that two orthogonal polarizations can be separated at the output using the proposed three waveguide structures. We also show that the proposed structure is robust against changes in phase mismatch parameters, as well as wavelength of operation.

  15. Electrode-induced digital-to-analog resistive switching in TaO x -based RRAM devices.

    Science.gov (United States)

    Li, Xinyi; Wu, Huaqiang; Bin Gao; Wu, Wei; Wu, Dong; Deng, Ning; Cai, Jian; Qian, He

    2016-07-29

    In RRAM devices, electrodes play a significant role during the switching process. In this paper, different top electrodes are used for TaO y /Ta2O5-x /AlO σ triple-oxide-layer devices. Top electrode-induced digital resistive switching to analog resistive switching was observed. For Pt top electrode (TE) devices, abrupt digital resistive switching behavior was observed, while Al TE devices showed gradual analog resistive switching behavior. Devices with various AlO σ thicknesses and sizes were fabricated and characterized to evaluate the reliability of the analog resistive switching. The physical mechanisms responsible for this electrode-induced resistive switching behavior were discussed.

  16. EFFECT OF CASEIN-BASED SEMISYNTHETIC FOOD ON RENAL ACID EXCRETION AND ACID-BASE STATE OF BLOOD IN DOGS

    NARCIS (Netherlands)

    ZIJLSTRA, WG; LANGBROEK, AJM; KRAAN, J; RISPENS, P; NIJMEIJER, A

    1995-01-01

    Urinary acid excretion and blood acid-base stare were determined in dogs fed a casein-based semi-synthetic food (SSF), to which different amounts of salts had been added, in comparison with feeding normal dog food. Net acid excretion (NAE) and inorganic acid excretion (IAE) increased during SSF feed

  17. Engineering a long-acting, potent GLP-1 analog for microstructure-based transdermal delivery.

    Science.gov (United States)

    Yang, Peng-Yu; Zou, Huafei; Chao, Elizabeth; Sherwood, Lance; Nunez, Vanessa; Keeney, Michael; Ghartey-Tagoe, Esi; Ding, Zhongli; Quirino, Herlinda; Luo, Xiaozhou; Welzel, Gus; Chen, Guohua; Singh, Parminder; Woods, Ashley K; Schultz, Peter G; Shen, Weijun

    2016-04-12

    Antidiabetic treatments aiming to reduce body weight are currently gaining increased interest. Exendin-4, a glucagon-like peptide-1 (GLP-1) receptor agonist administered twice daily via s.c. injection, improves glycemic control, often with associated weight reduction. To further improve the therapeutic efficacy of exendin-4, we have developed a novel peptide engineering strategy that incorporates a serum protein binding motif onto a covalent side-chain staple and applied to the peptide to enhance its helicity and, as a consequence, its potency and serum half-life. We demonstrated that one of the resulting peptides, E6, has significantly improved half-life and glucose tolerance in an oral glucose tolerance test in rodents. Chronic treatment of E6 significantly decreased body weight and fasting blood glucose, improved lipid metabolism, and also reduced hepatic steatosis in diet-induced obese mice. Moreover, the high potency of E6 allowed us to administer this peptide using a dissolvable microstructure-based transdermal delivery system. Pharmacokinetic and pharmacodynamic studies in guinea pigs showed that a single 5-min application of a microstructure system containing E6 significantly improved glucose tolerance for 96 h. This delivery strategy may offer an effective and patient-friendly alternative to currently marketed GLP-1 injectables and can likely be extended to other peptide hormones.

  18. Dual delivery systems based on polyamine analog BENSpm as prodrug and gene delivery vectors

    Science.gov (United States)

    Zhu, Yu

    Combination drug and gene therapy shows promise in cancer treatment. However, the success of such strategy requires careful selection of the therapeutic agents, as well as development of efficient delivery vectors. BENSpm (N 1, N11-bisethylnorspermine), a polyamine analogue targeting the intracellular polyamine pathway, draws our special attention because of the following reasons: (1) polyamine pathway is frequently dysregulated in cancer; (2) BENSpm exhibits multiple functions to interfere with the polyamine pathway, such as to up-regulate polyamine metabolism enzymes and down-regulate polyamine biosynthesis enzymes. Therefore BENSpm depletes all natural polyamines and leads to apoptosis and cell growth inhibition in a wide range of cancers; (3) preclinical studies proved that BENSpm can act synergistically with various chemotherapy agents, making it a promising candidate in combination therapy; (4) multiple positive charges in BENSpm enable it as a suitable building block for cationic polymers, which can be further applied to gene delivery. In this dissertation, our goal was to design dual-function delivery vector based on BENSpm that can function as a gene delivery vector and, after intracellular degradation, as an active anticancer agent targeting dysregulated polyamine metabolism. We first demonstrated strong synergism between BENSpm and a potential therapeutic gene product TRAIL. Strong synergism was obtained in both estrogen-dependent MCF-7 breast cancer cells and triple-negative MDA-MB-231 breast cancer cells. Significant dose reduction of TRAIL in combination with BENSpm in MDA-MB-231 cells, together with the fact that BENSpm rendered MCF-7 cells more sensitive to TRAIL treatment verified our rationale of designing BENSpm-based delivery platform. This was expected to be beneficial for overcoming drug resistance in chemotherapy, as well as boosting the therapeutic effect of therapeutic genes. We first designed a lipid-based BENSpm dual vector (Lipo

  19. Bipolar Membranes for Acid Base Flow Batteries

    Science.gov (United States)

    Anthamatten, Mitchell; Roddecha, Supacharee; Jorne, Jacob; Coughlan, Anna

    2011-03-01

    Rechargeable batteries can provide grid-scale electricity storage to match power generation with consumption and promote renewable energy sources. Flow batteries offer modular and flexible design, low cost per kWh and high efficiencies. A novel flow battery concept will be presented based on acid-base neutralization where protons (H+) and hydroxyl (OH-) ions react electrochemically to produce water. The large free energy of this highly reversible reaction can be stored chemically, and, upon discharge, can be harvested as usable electricity. The acid-base flow battery concept avoids the use of a sluggish oxygen electrode and utilizes the highly reversible hydrogen electrode, thus eliminating the need for expensive noble metal catalysts. The proposed flow battery is a hybrid of a battery and a fuel cell---hydrogen gas storing chemical energy is produced at one electrode and is immediately consumed at the other electrode. The two electrodes are exposed to low and high pH solutions, and these solutions are separated by a hybrid membrane containing a hybrid cation and anion exchange membrane (CEM/AEM). Membrane design will be discussed, along with ion-transport data for synthesized membranes.

  20. Biodegradable polyesters based on succinic acid

    Directory of Open Access Journals (Sweden)

    Nikolić Marija S.

    2003-01-01

    Full Text Available Two series of aliphatic polyesters based on succinic acid were synthesized by copolymerization with adipic acid for the first series of saturated polyesters, and with fumaric acid for the second series. Polyesters were prepared starting from the corresponding dimethyl esters and 1,4-butanediol by melt transesterification in the presence of a highly effective catalyst tetra-n-butyl-titanate, Ti(0Bu4. The molecular structure and composition of the copolyesters was determined by 1H NMR spectroscopy. The effect of copolymer composition on the physical and thermal properties of these random polyesters were investigated using differential scanning calorimetry. The degree of crystallinity was determined by DSC and wide angle X-ray. The degrees of crystallinity of the saturated and unsaturated copolyesters were generally reduced with respect to poly(butylene succinate, PBS. The melting temperatures of the saturated polyesters were lower, while the melting temperatures of the unsaturated copolyesters were higher than the melting temperature of PBS. The biodegradability of the polyesters was investigated by enzymatic degradation tests. The enzymatic degradation tests were performed in a buffer solution with Candida cylindracea lipase and for the unsaturated polyesters with Rhizopus arrhizus lipase. The extent of biodegradation was quantified as the weight loss of polyester films. Also the surface of the polyester films after degradation was observed using optical microscopy. It could be concluded that the biodegradability depended strongly on the degree of crystallinity, but also on the flexibility of the chain backbone. The highest biodegradation was observed for copolyesters containing 50 mol.% of adipic acid units, and in the series of unsaturated polyesters for copolyesters containing 5 and 10 mol.% of fumarate units. Although the degree of crystallinity of the unsaturated polyesters decreased slightly with increasing unsaturation, the biodegradation

  1. The Effect of Combining Analogy-Based Simulation and Laboratory Activities on Turkish Elementary School Students' Understanding of Simple Electric Circuits

    Science.gov (United States)

    Unlu, Zeynep Koyunlu; Dokme, Ibilge

    2011-01-01

    The purpose of this study was to investigate whether the combination of both analogy-based simulation and laboratory activities as a teaching tool was more effective than utilizing them separately in teaching the concepts of simple electricity. The quasi-experimental design that involved 66 seventh grade students from urban Turkish elementary…

  2. Structure-based design and synthesis of a bivalent iminobiotin analog showing strong affinity toward a low immunogenic streptavidin mutant.

    Science.gov (United States)

    Kawato, Tatsuya; Mizohata, Eiichi; Shimizu, Yohei; Meshizuka, Tomohiro; Yamamoto, Tomohiro; Takasu, Noriaki; Matsuoka, Masahiro; Matsumura, Hiroyoshi; Kodama, Tatsuhiko; Kanai, Motomu; Doi, Hirofumi; Inoue, Tsuyoshi; Sugiyama, Akira

    2015-01-01

    The streptavidin/biotin interaction has been widely used as a useful tool in research fields. For application to a pre-targeting system, we previously developed a streptavidin mutant that binds to an iminobiotin analog while abolishing affinity for natural biocytin. Here, we design a bivalent iminobiotin analog that shows 1000-fold higher affinity than before, and determine its crystal structure complexed with the mutant protein.

  3. Teaching Acid/Base Physiology in the Laboratory

    Science.gov (United States)

    Friis, Ulla G.; Plovsing, Ronni; Hansen, Klaus; Laursen, Bent G.; Wallstedt, Birgitta

    2010-01-01

    Acid/base homeostasis is one of the most difficult subdisciplines of physiology for medical students to master. A different approach, where theory and practice are linked, might help students develop a deeper understanding of acid/base homeostasis. We therefore set out to develop a laboratory exercise in acid/base physiology that would provide…

  4. Using Willie's Acid-Base Box for Blood Gas Analysis

    Science.gov (United States)

    Dietz, John R.

    2011-01-01

    In this article, the author describes a method developed by Dr. William T. Lipscomb for teaching blood gas analysis of acid-base status and provides three examples using Willie's acid-base box. Willie's acid-base box is constructed using three of the parameters of standard arterial blood gas analysis: (1) pH; (2) bicarbonate; and (3) CO[subscript…

  5. Using Willie's Acid-Base Box for Blood Gas Analysis

    Science.gov (United States)

    Dietz, John R.

    2011-01-01

    In this article, the author describes a method developed by Dr. William T. Lipscomb for teaching blood gas analysis of acid-base status and provides three examples using Willie's acid-base box. Willie's acid-base box is constructed using three of the parameters of standard arterial blood gas analysis: (1) pH; (2) bicarbonate; and (3) CO[subscript…

  6. Assessing College Students' Understanding of Acid Base Chemistry Concepts

    Science.gov (United States)

    Wan, Yanjun Jean

    2014-01-01

    Typically most college curricula include three acid base models: Arrhenius', Bronsted-Lowry's, and Lewis'. Although Lewis' acid base model is generally thought to be the most sophisticated among these three models, and can be further applied in reaction mechanisms, most general chemistry curricula either do not include Lewis' acid base model, or…

  7. Teaching Acid/Base Physiology in the Laboratory

    Science.gov (United States)

    Friis, Ulla G.; Plovsing, Ronni; Hansen, Klaus; Laursen, Bent G.; Wallstedt, Birgitta

    2010-01-01

    Acid/base homeostasis is one of the most difficult subdisciplines of physiology for medical students to master. A different approach, where theory and practice are linked, might help students develop a deeper understanding of acid/base homeostasis. We therefore set out to develop a laboratory exercise in acid/base physiology that would provide…

  8. A 97 dB dynamic range CSA-based readout circuit with analog temperature compensation for MEMS capacitive sensors

    Science.gov (United States)

    Tao, Yin; Chong, Zhang; Huanming, Wu; Qisong, Wu; Haigang, Yang

    2013-11-01

    This paper presents a charge-sensitive-amplifier (CSA) based readout circuit for capacitive microelectro-mechanical-system (MEMS) sensors. A continuous-time (CT) readout structure using the chopper technique is adopted to cancel the low frequency noise and improve the resolution of the readout circuits. An operational trans-conductance amplifier (OTA) structure with an auxiliary common-mode-feedback-OTA is proposed in the fully differential CSA to suppress the chopper modulation induced disturbance at the OTA input terminal. An analog temperature compensation method is proposed, which adjusts the chopper signal amplitude with temperature variation to compensate the temperature drift of the CSA readout sensitivity. The chip is designed and implemented in a 0.35 μm CMOS process and is 2.1 × 2.1 mm2 in area. The measurement shows that the readout circuit achieves 0.9 aF / √Hz capacitive resolution, 97 dB dynamic range in 100 Hz signal bandwidth, and 0.8 mV/fF sensitivity with a temperature drift of 35 ppm/°C after optimized compensation.

  9. Potential applications of curcumin and its novel synthetic analogs and nanotechnology-based formulations in cancer prevention and therapy

    Directory of Open Access Journals (Sweden)

    Batra Surinder K

    2011-08-01

    Full Text Available Abstract Curcumin has attracted great attention in the therapeutic arsenal in clinical oncology due to its chemopreventive, antitumoral, radiosensibilizing and chemosensibilizing activities against various types of aggressive and recurrent cancers. These malignancies include leukemias, lymphomas, multiple myeloma, brain cancer, melanoma and skin, lung, prostate, breast, ovarian, liver, gastrointestinal, pancreatic and colorectal epithelial cancers. Curcumin mediates its anti-proliferative, anti-invasive and apoptotic effects on cancer cells, including cancer stem/progenitor cells and their progenies, through multiple molecular mechanisms. The oncogenic pathways inhibited by curcumin encompass the members of epidermal growth factor receptors (EGFR and erbB2, sonic hedgehog (SHH/GLIs and Wnt/β-catenin and downstream signaling elements such as Akt, nuclear factor-kappa B (NF-κB and signal transducers and activators of transcription (STATs. In counterbalance, the high metabolic instability and poor systemic bioavailability of curcumin limit its therapeutic efficacy in human. Of great therapeutic interest, the selective delivery of synthetic analogs or nanotechnology-based formulations of curcumin to tumors, alone or in combination with other anticancer drugs, may improve their chemopreventive and chemotherapeutic efficacies against cancer progression and relapse. Novel curcumin formulations may also be used to reverse drug resistance, eradicate the total cancer cell mass and improve the anticarcinogenic efficacy of the current anti-hormonal and chemotherapeutic treatments for patients with various aggressive and lethal cancers.

  10. Photonic compressive sensing for analog-to-information conversion with a delay-line based microwave photonic filter

    Science.gov (United States)

    Zhu, Zhijing; Chi, Hao; Jin, Tao; Zheng, Shilie; Jin, Xiaofeng; Zhang, Xianmin

    2016-07-01

    Compressive sensing (CS) in the photonic domain is highly promising for analog-to-information conversion of sparse signals due to its potential capability of high input bandwidth and digitization with sub-Nyquist sampling. In this paper, we suggest that the concept of delay-line based microwave photonic filter be used in photonic CS to realize the low-pass filtering (LPF) function which is required in CS. A microwave photonic filter (MPF) with a dispersive element and fiber delay lines is applied in photonic CS to achieve better performance and flexibility. In the approach, the input radio-frequency signal and the pseudorandom bit sequence (PRBS) are modulated on a multi-wavelength optical carrier and propagate through a dispersive element. The modulated optical signal is split into multiple channels with tunable delay lines. The multiple wavelengths, dispersive element and multiple channels constitute a reconfigurable low-pass microwave filter. Experiment and simulations are presented to demonstrate the feasibility and potentials of this approach.

  11. The μ3 model of acids and bases: extending the Lewis theory to intermetallics.

    Science.gov (United States)

    Stacey, Timothy E; Fredrickson, Daniel C

    2012-04-02

    A central challenge in the design of new metallic materials is the elucidation of the chemical factors underlying the structures of intermetallic compounds. Analogies to molecular bonding phenomena, such as the Zintl concept, have proven very productive in approaching this goal. In this Article, we extend a foundational concept of molecular chemistry to intermetallics: the Lewis theory of acids and bases. The connection is developed through the method of moments, as applied to DFT-calibrated Hückel calculations. We begin by illustrating that the third and fourth moments (μ(3) and μ(4)) of the electronic density of states (DOS) distribution tune the properties of a pseudogap. μ(3) controls the balance of states above and below the DOS minimum, with μ(4) then determining the minimum's depth. In this way, μ(3) predicts an ideal occupancy for the DOS distribution. The μ(3)-ideal electron count is used to forge a link between the reactivity of transition metals toward intermetallic phase formation, and that of Lewis acids and bases toward adduct formation. This is accomplished through a moments-based definition of acidity which classifies systems that are electron-poor relative to the μ(3)-ideal as μ(3)-acidic, and those that are electron-rich as μ(3)-basic. The reaction of μ(3) acids and bases, whether in the formation of a Lewis acid/base adduct or an intermetallic phase, tends to neutralize the μ(3) acidity or basicity of the reactants. This μ(3)-neutralization is traced to the influence of electronegativity differences at heteroatomic contacts on the projected DOS curves of the atoms involved. The role of μ(3)-acid/base interactions in intermetallic phases is demonstrated through the examination of 23 binary phases forming between 3d metals, the stability range of the CsCl type, and structural trends within the Ti-Ni system.

  12. Liquid Crystalline Furandicarboxylic Acid-based Aaromatic Polyesters

    NARCIS (Netherlands)

    WILSENS, CAROLUS HENRICUS R. MARIA; RASTOGI, SANJAY; VELD, MARTIJN ARNOLDUS JOHANNES; KLOP, ENNO ANTON; NOORDOVER, BART ADRIANUS JOHANNES

    2013-01-01

    The invention pertains to a fully aromatic liquid crystalline furandicarboxylic acid- based aromatic polyester obtainable from a mixture of monomers comprising 2,5- furandicarboxylic acid, p-hydroxybenzoic acid, an aromatic diol, and 5-40 mol% of an aromatic monocarboxylic acid selected from vanilli

  13. Delayed administration of the nucleic acid analog 2Cl-C.OXT-A attenuates brain damage and enhances functional recovery after ischemic stroke.

    Science.gov (United States)

    Okabe, Naohiko; Nakamura, Emi; Himi, Naoyuki; Narita, Kazuhiko; Tsukamoto, Ikuko; Maruyama, Tokumi; Sakakibara, Norikazu; Nakamura, Takehiro; Itano, Toshifumi; Miyamoto, Osamu

    2013-04-19

    2Cl-C.OXT-A (COA-Cl) is a novel nucleic acid analog that enhances angiogenesis through extracellular signal-regulated kinase 1 or 2 (ERK1/2) activation. ERK1/2 is a well-known kinase that regulates cell survival, proliferation and differentiation in the central nervous system. We performed in vitro and in vivo experiments to investigate whether COA-Cl can attenuate neuronal damage and enhance recovery after brain ischemia. In primary cortical neuron cultures, COA-Cl prevented neuronal injury after 2h of oxygen-glucose deprivation. COA-Cl increased phospho-ERK levels in a dose-dependent manner and COA-Cl-induced neuroprotection and ERK1/2 activation was inhibited by suramin or PD98059. The effect of COA-Cl was evaluated in vivo with 60min of middle cerebral artery occlusion combined with bilateral common carotid artery occlusion. COA-Cl or saline was injected intracerebroventricularly 5min after reperfusion. COA-Cl significantly reduced infarct volume and improved neurological deficits upon injection of 15 or 30μg/kg COA-Cl. Moreover, COA-Cl reduced the number of TUNEL positive cells in ischemic boundary, while rCBF was not significantly changed by COA-Cl administration. We also evaluated the effect of delayed COA-Cl administration on recovery from brain ischemia by continuous administration of COA-Cl from 1 to 8 days after reperfusion. Delayed continuous COA-Cl administration also reduced infarct volume. Furthermore, COA-Cl enhanced peri-infarct angiogenesis and synaptogenesis, resulting in improved motor function recovery. Our findings demonstrate that COA-Cl exerts both neuroprotective and neurorestorative effects over a broad therapeutic time window, suggesting COA-Cl might be a novel and potent therapeutic agent for ischemic stroke.

  14. Behavior of the guanine base in G-quadruplexes probed by the fluorescent guanine analog, 6-methyl isozanthopterin

    Energy Technology Data Exchange (ETDEWEB)

    Han, Ji Hoon; Chitrapriya, Nataraj; Lee, Hyun Suk; Lee, Young Ae; Kim, Seog K. [Dept. of Chemistry, Yeungnam University, Gyeongsan (Korea, Republic of); Jung, Maeng Joon [Dept. of Chemistry, Kyungpook National University, Daegu (Korea, Republic of)

    2017-02-15

    In this study, circular dichroism (CD) spectrum and fluorescence techniques were used to examine the dynamic properties and microenvironment of the guanine base (G) at the central loop and at the middle of the G-stem of the G-quadruplex formed from the G{sub 3}T{sub 2}G{sub 3}TGTG{sub 3}T{sub 2}G{sub 3} sequence (G-quadruplex 1), in which the G base at the 10th and 13th position were replaced with a fluorescent G analog, 6-methyl isoxanthopterin (6MI) (G-quadruplex 2 and 3, respectively). For all G-quadruplexes, the CD spectrum revealed a positive band at 263 nm and a shoulder at 298 nm, and the thermal melting profiles were the sum of at least two sigmoidal curves. These observations indicated the presence of two conformers in the G-quadruplex. The fluorescence intensity of G-quadruplex 2 was greater than 3, as expected from the extent of stacking interaction, which is larger in the G(6MI)G sequence than the T(6MI)T sequence. The efficiency of fluorescence quenching by the polar acrylamide quencher and negatively charged I− quencher were larger for G-quadruplex 3, suggesting that 6MI in the G(6MI)G stem is exposed more to the aqueous environment compared to that in the T(6MI)T central loop. In the latter case, 6MI may direct to the center of the top G-quartet layer. The possibility of hydrogen bond formation between the carbonyl group of 6MI and the acrylamide of the G-quadruplex 3 was proposed.

  15. Reasoning by Analogy in Constructing Mathematical Ideas.

    Science.gov (United States)

    English, Lyn D.

    A powerful way of understanding something new is by analogy with something already known. An analogy is defined as a mapping from one structure, which is already known (the base or source), to another structure that is to be inferred or discovered (the target). The research community has given considerable attention to analogical reasoning in the…

  16. Terrestrial Spaceflight Analogs: Antarctica

    Science.gov (United States)

    Crucian, Brian

    2013-01-01

    Alterations in immune cell distribution and function, circadian misalignment, stress and latent viral reactivation appear to persist during Antarctic winterover at Concordia Station. Some of these changes are similar to those observed in Astronauts, either during or immediately following spaceflight. Others are unique to the Concordia analog. Based on some initial immune data and environmental conditions, Concordia winterover may be an appropriate analog for some flight-associated immune system changes and mission stress effects. An ongoing smaller control study at Neumayer III will address the influence of the hypoxic variable. Changes were observed in the peripheral blood leukocyte distribution consistent with immune mobilization, and similar to those observed during spaceflight. Alterations in cytokine production profiles were observed during winterover that are distinct from those observed during spaceflight, but potentially consistent with those observed during persistent hypobaric hypoxia. The reactivation of latent herpesviruses was observed during overwinter/isolation, that is consistently associated with dysregulation in immune function.

  17. Bedside Analysis of Acid-Base Balance

    Directory of Open Access Journals (Sweden)

    Yu. S. Podlesskikh

    2006-01-01

    Full Text Available Laboratory service is one of the most hang-the-expense items in the cost of treatment of patients in an intensive care unit. Isolated acid-base balance (ABB impairments are rare in clinical practice. These impairments are generally combined and they frequently cause a drastic change in the pH value of blood. Early detection of their origin and its elimination are of profound importance in these situations. Miniaturization of analyzers has made it possible to conduct some investigations and particularly to determine ABB just in the intensive care unit or operating suite. The attached software permits creation of a database and transmission of information to the laboratory network. One year’s experience has indicated that the quality of reagents and reference substances allows real-time determination of the values of ABB with a high degree of accuracy and reproducibility at a patient’s bed. 

  18. Genome-wide mutation avalanches induced in diploid yeast cells by a base analog or an APOBEC deaminase.

    Directory of Open Access Journals (Sweden)

    Artem G Lada

    Full Text Available Genetic information should be accurately transmitted from cell to cell; conversely, the adaptation in evolution and disease is fueled by mutations. In the case of cancer development, multiple genetic changes happen in somatic diploid cells. Most classic studies of the molecular mechanisms of mutagenesis have been performed in haploids. We demonstrate that the parameters of the mutation process are different in diploid cell populations. The genomes of drug-resistant mutants induced in yeast diploids by base analog 6-hydroxylaminopurine (HAP or AID/APOBEC cytosine deaminase PmCDA1 from lamprey carried a stunning load of thousands of unselected mutations. Haploid mutants contained almost an order of magnitude fewer mutations. To explain this, we propose that the distribution of induced mutation rates in the cell population is uneven. The mutants in diploids with coincidental mutations in the two copies of the reporter gene arise from a fraction of cells that are transiently hypersensitive to the mutagenic action of a given mutagen. The progeny of such cells were never recovered in haploids due to the lethality caused by the inactivation of single-copy essential genes in cells with too many induced mutations. In diploid cells, the progeny of hypersensitive cells survived, but their genomes were saturated by heterozygous mutations. The reason for the hypermutability of cells could be transient faults of the mutation prevention pathways, like sanitization of nucleotide pools for HAP or an elevated expression of the PmCDA1 gene or the temporary inability of the destruction of the deaminase. The hypothesis on spikes of mutability may explain the sudden acquisition of multiple mutational changes during evolution and carcinogenesis.

  19. Analog and VLSI circuits

    CERN Document Server

    Chen, Wai-Kai

    2009-01-01

    Featuring hundreds of illustrations and references, this book provides the information on analog and VLSI circuits. It focuses on analog integrated circuits, presenting the knowledge on monolithic device models, analog circuit cells, high performance analog circuits, RF communication circuits, and PLL circuits.

  20. Transport Selectivity of a Diethylene Glycol Dimethacrylate-Based Thymine-imprinted Polymeric Membrane over a Cellulose Support for Nucleic Acid Bases

    Institute of Scientific and Technical Information of China (English)

    QU Xiang-Jin; CHEN Chang-Bao; ZHOU Jie; WU Chun-Hui

    2007-01-01

    The binding mechanism between 9-vinyladenine and pyrimidine base thymine in methanol was studied with UV-visible spectrophotometric method. Based on this study, using thymine as a template molecule, 9-vinyladenine as a novel functional monomer and diethylene glycol dimethacrylate as a new cross-linker, a specific diethylene glycol dimethacrylate-based molecularly imprinted polymeric membrane was prepared over a cellulose support.Then, the resultantly polymeric membrane morphologies were visualized with scanning electron microscopy and its permselectivity was examined using thymine, uracil, cytosine, adenine and guanine as substrates. This result showed that the imprinting polymeric membrane prepared with diethylene glycol dimethacrylate exhibited higher transport capacity for the template molecule thymine and its optimal analog uracil than other nucleic acid bases. The membrane also took on higher permselectivity than the imprinted membrane made with ethylene glycol dimethacrylate as a cross-linker. When a mixture including five nucleic acid bases thymine, uracil, cytosine, adenine and guanine passed through the diethylene glycol dimethacrylate-based thymine-imprinted polymeric membrane,recognition of the membrane for the template molecule thymine and its optimal analog uracil was demonstrated. It was predicted that the molecularly imprinted membrane prepared with diethylene glycol dimethacrylate as cross-linker might be applicable to thymine assay of absolute hydrolysates of DNA or uracil assay of absolute hydrolysates of RNA in biological samples because of its high selectivity for the template molecule thymine and its optimal analog uracil.

  1. Physico-Chemical, and Sensory Properties of Soy Based Gouda Cheese Analog Made from Different Concentration of Fat, Sodium Citrate and Various Cheese Starter Cultures

    OpenAIRE

    Abu Amar; Ingrid Surono

    2013-01-01

    Gouda cheese analog (GCA) was made using soy protein isolate (SPI), skim milk powder (SMP), fat (palm fat and butter fat), and water (W) at optimal ratio of SPI : SMP : F : W = 14 : 6 : 20 : 60. The effects of butter fat, sodium citrate, and cheese starter culture on the sensory properties of ripened product were assessed by preference test, hedonic test, and the texture profile analysis (TPA) of GCA. The free fatty acids, water-soluble nitrogen, and reduction in pH value of progel were also ...

  2. Whole-body acid-base modeling revisited

    DEFF Research Database (Denmark)

    Ring, Troels; Nielsen, Søren

    2017-01-01

    The textbook account of whole-body acid-base balance in terms of endogenous acid production, renal net acid excretion and gastrointestinal alkali absorption which is the only comprehensive model around, has never been applied in clinical practice or been formally validated. In order to improve...... understanding of acid-base modeling, we managed to write up this conventional model as an expression solely on urine chemistry. Renal net acid excretion and endogenous acid production was already formulated in terms of urine chemistry, and we could from the literature also see gastrointestinal alkali absorption...

  3. 基于边界扫描的模拟电路BIT技术研究%Research on BIT for Analog Circuit Based on Boundary Scan Technology

    Institute of Scientific and Technical Information of China (English)

    冯长江; 薛冰; 李晓峰

    2012-01-01

    Most of the analog circuit testable design based on boundary scan which still uses the analog test bus prescribed by IEEE1149. 4 standard has not been realized the built-in-test design actually. The extraction and comparison of analog signal are difficult. According to these problems, a design of BIT structure for analog circuit based on boundary scan is presented, which takes the rectangular pulse as actuator and uses analog switch as auxiliary bridge. Each module function timing results show the rationality of the design, and to integrate op-amp uA741 as measured circuit, the pulse count of the signal rising edge fully proves the feasibility of the structure.%边界扫描技术在模拟电路的可测性设计大多仍停留在IEEE1149.4标准所规定的模拟测试总线上,并没有做到真正意义上的内建自测试设计;针对模拟电路信号提取和比较相对困难的测试难点,提出采用方波脉冲作为测试激励信号的方法,并以模拟开关为辅助桥梁,设计了基于边界扫描的模拟电路BIT结构;通过各个模块功能的时序仿真证明了该结构设计的合理性,并以集成运放uA741作为被测电路,通过信号上升沿脉冲计数充分证明该结构的可行性.

  4. When Gesture Becomes Analogy.

    Science.gov (United States)

    Cooperrider, Kensy; Goldin-Meadow, Susan

    2017-07-01

    Analogy researchers do not often examine gesture, and gesture researchers do not often borrow ideas from the study of analogy. One borrowable idea from the world of analogy is the importance of distinguishing between attributes and relations. Gentner (, ) observed that some metaphors highlight attributes and others highlight relations, and called the latter analogies. Mirroring this logic, we observe that some metaphoric gestures represent attributes and others represent relations, and propose to call the latter analogical gestures. We provide examples of such analogical gestures and show how they relate to the categories of iconic and metaphoric gestures described previously. Analogical gestures represent different types of relations and different degrees of relational complexity, and sometimes cohere into larger analogical models. Treating analogical gestures as a distinct phenomenon prompts new questions and predictions, and illustrates one way that the study of gesture and the study of analogy can be mutually informative. Copyright © 2017 Cognitive Science Society, Inc.

  5. A novel, mild, specific and indirect maleimido-based radioiodolabeling method; Radiolabeling of analogs derived from parathyroid hormone (PTH) and PTH-related protein (PTHrP)

    Energy Technology Data Exchange (ETDEWEB)

    Chorev, M.; Caulfield, M.P.; Roubini, E.; McKee, R.L.; Gibbons, S.W.; Chih-Tai Leu; Levy, J.J.; Rosenblatt, M.

    1992-01-01

    In an effort to design a mild, non-oxidative and site-specific means of radiolabeling bioactive molecules we have employed maleimido-sulfhydryl chemistry to produce bioactive hormone radioligands. We have prepared two novel radioiodolabeled reagents, 3'-maleimidopropanoyl-3-[sup 125]I-tyramide and its retro analog, N-maleoyl-N'-3-(4-hydroxy-3-[sup 125]I-phenyl)propanoyl ethylenediamide, by either oxidative radioiodination of the precursors or radiolabeling of the phenolic component prior to its incorporation into the radiolabeling reagents. These reagents were then used to radiolabel analogs of parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) in an efficient way, yielding reaction mixtures which were easily purified. The radioligands obtained are stable upon storage and bind in an reversible manner to a single population of binding sites displaying affinity in the low nanomolar range. The potencies of these analogs are comparable to the non-modified PTH and PTH rP analogs. This study demonstrates the utility of the novel maleimido-based indirect radioiodination approach and highlights some of its advantages over either direct oxidative procedures or acylation using the Bolton-Hunter reagent. (au).

  6. Formation of a Phyllosilicate-, K-feldspar-, and Sulfate-Bearing Hematite Ridge on Mauna Kea Volcano, Hawaii, Under Hydrothermal, Acid-Sulfate Conditions: Process and Mineralogical Analog for the Hematite Ridge on Mt. Sharp, Gale Crater, Mars.

    Science.gov (United States)

    Ming, D. W.; Morris, R. V.; Adams, M. E.; Catalano, J. G.; Graff, T. G.; Arvidson, R. E.; Guinness, E. A.; Hamilton, J. C.; Mertzman, S. A.; Fraeman, A.

    2015-12-01

    The Mars Science Laboratory rover Curiosity is currently moving upslope on Mt. Sharp in Gale Crater toward a hematite-bearing ridge. This hematite exposure was originally detected in CRISM spectra and subsequently mapped as part of a ~200 m wide, 6.5 km long ridge extending roughly parallel to the base of Mt. Sharp. CRISM spectra in the region suggest that hematite, smectite, and hydrated sulfates occur as secondary phases in lower layers of Mt. Sharp, separated by an unconformity from overlying anhydrous strata. A potential process and mineralogical analog is a hematite-bearing and weathering-resistant stratum (ridge) is exposed on the Puu Poliahu cinder cone on Mauna Kea (MK) volcano, Hawaii. The MK ridge is the product of hydrothermal alteration of basaltic precursors under acid-sulfate conditions. We are acquiring chemical and mineralogical (VNIR, Mid-IR, and backscatter Moessbauer spectroscopy, and transmission XRD) data on the MK ridge area that correspond to rover and orbiting spacecraft measurements at Gale Crater and elsewhere. The hematite-bearing stratum does not have detectable sulfate minerals by XRD, and hematite is variably present as up to mm-sized black crystals which, together with associated trioctahedral smectite and K-feldspar (from XRD), imply hydrothermal conditions. Adjacent to the MK hematite-bearing stratum are sulfates (jarosite and alunite) that are evidence for aqueous alteration under acid-sulfate conditions, and more soluble sulfates are absent but such phases would not persist if formed because of annual precipitation. Dioctahedral smectite is associated with red hematite and alunite-rich samples. The black and red hematite zones have the highest and lowest MgO/Al2O3 and K2O/Na2O ratios, respectively. Hematite, smectite, jarosite, and K-feldspar have been detected by Curiosity XRD downslope from the Mt. Sharp hematite ridge. MK field work and samples were obtained with PISCES partnership and OMKM, MKMB, BLNR, and KKMC permissions.

  7. A Fault Signature Characterization Based Analog Circuit Testing Scheme and the Extension of IEEE 1149.4 Standard

    Science.gov (United States)

    San-Um, Wimol; Tachibana, Masayoshi

    An analog circuit testing scheme is presented. The testing technique is a sinusoidal fault signature characterization, involving the measurement of DC offset, amplitude, frequency and phase shift, and the realization of two crossing level voltages. The testing system is an extension of the IEEE 1149.4 standard through the modification of an analog boundary module, affording functionalities for both on-chip testing capability, and accessibility to internal components for off-chip testing. A demonstrating circuit-under-test, a 4th-order Gm-C low-pass filter, and the proposed analog testing scheme are implemented in a physical level using 0.18-µm CMOS technology, and simulated using Hspice. Both catastrophic and parametric faults are potentially detectable at the minimum parameter variation of 0.5%. The fault coverage associated with CMOS transconductance operational amplifiers and capacitors are at 94.16% and 100%, respectively. This work offers the enhancement of standardizing test approach, which reduces the complexity of testing circuit and provides non-intrusive analog circuit testing.

  8. Identification of acid-base catalytic residues of high-Mr thioredoxin reductase from Plasmodium falciparum.

    Science.gov (United States)

    McMillan, Paul J; Arscott, L David; Ballou, David P; Becker, Katja; Williams, Charles H; Müller, Sylke

    2006-11-03

    High-M(r) thioredoxin reductase from the malaria parasite Plasmodium falciparum (PfTrxR) contains three redox active centers (FAD, Cys-88/Cys-93, and Cys-535/Cys-540) that are in redox communication. The catalytic mechanism of PfTrxR, which involves dithiol-disulfide interchanges requiring acid-base catalysis, was studied by steady-state kinetics, spectral analyses of anaerobic static titrations, and rapid kinetics analysis of wild-type enzyme and variants involving the His-509-Glu-514 dyad as the presumed acid-base catalyst. The dyad is conserved in all members of the enzyme family. Substitution of His-509 with glutamine and Glu-514 with alanine led to TrxR with only 0.5 and 7% of wild type activity, respectively, thus demonstrating the crucial roles of these residues for enzymatic activity. The H509Q variant had rate constants in both the reductive and oxidative half-reactions that were dramatically less than those of wild-type enzyme, and no thiolateflavin charge-transfer complex was observed. Glu-514 was shown to be involved in dithiol-disulfide interchange between the Cys-88/Cys-93 and Cys-535/Cys-540 pairs. In addition, Glu-514 appears to greatly enhance the role of His-509 in acid-base catalysis. It can be concluded that the His-509-Glu-514 dyad, in analogy to those in related oxidoreductases, acts as the acid-base catalyst in PfTrxR.

  9. Acid-base bifunctional catalytic surfaces for nucleophilic addition reactions.

    Science.gov (United States)

    Motokura, Ken; Tada, Mizuki; Iwasawa, Yasuhiro

    2008-09-01

    This article illustrates the modification of oxide surfaces with organic amine functional groups to create acid-base bifunctional catalysts, summarizing our previous reports and also presenting new data. Immobilization of organic amines as bases on inorganic solid-acid surfaces afforded highly active acid-base bifunctional catalysts, which enabled various organic transformations including C--C coupling reactions, though these reactions did not proceed with either the homogeneous amine precursors or the acidic supports alone. Spectroscopic characterization, such as by solid-state MAS NMR and FTIR, revealed not only the interactions between acidic and basic sites but also bifunctional catalytic reaction mechanisms.

  10. The use of J-coupling as a sole criterion to assign the total absolute stereochemistry of new pyrrolidinone class synthetic analogs, derived from S-pyroglutamic acid

    Science.gov (United States)

    Kellici, Tahsin F.; Ntountaniotis, Dimitrios; Vanioti, Marianna; Golic Grdadolnik, Simona; Simcic, Mihael; Michas, Georgios; Moutevelis-Minakakis, Panagiota; Mavromoustakos, Thomas

    2017-02-01

    During the synthesis of new pyrrolidinone analogs possessing biological activity it is intriguing to assign their absolute stereochemistry as it is well known that drug potency is influenced by the stereochemistry. The combination of J-coupling information with theoretical results was used in order to establish their total stereochemistry when the chiral center of the starting material has known absolute stereochemistry. The J-coupling can be used as a sole criterion for novel synthetic analogs to identify the right stereochemistry. This approach is extremely useful especially in the case of analogs whose 2D NOESY spectra cannot provide this information. Few synthetic examples are given to prove the significance of this approach.

  11. ACID-BASE INTERACTIONS BETWEEN POLYMERS AND FILLERS

    Institute of Scientific and Technical Information of China (English)

    WANG Qingguo; CHEN Fute; HUANG Yuanfu; ZHOU Qingli

    1987-01-01

    Inverse gas chromatography(IGC) and Fourier-transform infrared (FT-IR) techniques were applied to determining the relative acid-base strength of polymers and coupling agents. The acid-base characteristics of fillers such as CaCO3 could be altered by treatment with different coupling agents. It was shown that some mechanical properties of filled polymers were obviously associated with acid-base interactions between polymers and fillers.

  12. Learning by Analogy: Discriminating between Potential Analogs

    Science.gov (United States)

    Richland, Lindsey E.; McDonough, Ian M.

    2010-01-01

    The ability to successfully discriminate between multiple potentially relevant source analogs when solving new problems is crucial to proficiency in a mathematics domain. Experimental findings in two different mathematical contexts demonstrate that providing cues to support comparative reasoning during an initial instructional analogy, relative to…

  13. Acid-base strengths in pyridine

    NARCIS (Netherlands)

    Bos, M.; Dahmen, E.A.M.F.

    1971-01-01

    Although pyridine is a solvent with a low dielectric constant, spectrophotometric determinations show simple dissociation without ion pairs as intermediates for some sulfonphthaleins and polynitrophenols in pyridine. The salts of a number of amines and hydrochloric acid, perchloric acid and picric

  14. Quinoline based receptor in fluorometric discrimination of carboxylic acids

    Directory of Open Access Journals (Sweden)

    2008-12-01

    Full Text Available Quinoline and naphthalene-based fluororeceptors 1 and 2 have been designed and synthesized for detection of hydroxy carboxylic acids in less polar solvents. The receptor 1 shows monomer emission quenching followed by excimer emission upon hydrogen bond-mediated complexation of carboxylic acids. The excimer emission distinguishes aromatic dicarboxylic acids from aliphatic dicarboxylic acids and even long chain aliphatic dicarboxylic acids from short chain aliphatic dicarboxylic acids. The receptor 1 is found to be selective for citric acid with a strong excimer emission in CHCl3. On the contrary, the receptor 2 exhibited less binding constant value and did not form any excimer upon complexation with the same acids under similar conditions. This established the role of quinoline ring nitrogen in binding with the acids.

  15. Intuitive analog circuit design

    CERN Document Server

    Thompson, Marc

    2013-01-01

    Intuitive Analog Circuit Design outlines ways of thinking about analog circuits and systems that let you develop a feel for what a good, working analog circuit design should be. This book reflects author Marc Thompson's 30 years of experience designing analog and power electronics circuits and teaching graduate-level analog circuit design, and is the ideal reference for anyone who needs a straightforward introduction to the subject. In this book, Dr. Thompson describes intuitive and ""back-of-the-envelope"" techniques for designing and analyzing analog circuits, including transistor amplifi

  16. Enhanced Acid/Base Catalysis in High Temperature Liquid Water

    Institute of Scientific and Technical Information of China (English)

    Xiu Yang LU; Qi JING; Zhun LI; Lei YUAN; Fei GAO; Xin LIU

    2006-01-01

    Two novel and environmentally benign solvent systems, organic acids-enriched high temperature liquid water (HTLW) and NH3-enriched HTLW, were developed, which can enhance the reaction rate of acid/base-catalyzed organic reactions in HTLW. We investigated the decomposition of fructose in organic acids-enriched HTLW, hydrolysis of cinnamaldehyde and aldol condensation of phenylaldehyde with acetaldehyde in NH3-enriched HTLW. The experimental results demonstrated that organic acids-enriched or NH3-enriched HTLW can greatly accelerate acid/base-catalyzed organic reactions in HTLW.

  17. Recognition of Nucleic Acid Junctions Using Triptycene-Based Molecules

    OpenAIRE

    Barros, Stephanie A.; Chenoweth, David M.

    2014-01-01

    Nucleic acid modulation by small molecules is an essential process across the kingdoms of life. Targeting nucleic acids with small molecules represents a significant challenge at the forefront of chemical biology. Nucleic acid junctions are ubiquitous structural motifs in nature and in designed materials. Herein, we describe a new class of structure specific nucleic acid junction stabilizers based on a triptycene scaffold. Triptycenes provide significant stabilization of DNA and RNA three-way...

  18. History of medical understanding and misunderstanding of Acid base balance.

    Science.gov (United States)

    Aiken, Christopher Geoffrey Alexander

    2013-09-01

    To establish how controversies in understanding acid base balance arose, the literature on acid base balance was reviewed from 1909, when Henderson described how the neutral reaction of blood is determined by carbonic and organic acids being in equilibrium with an excess of mineral bases over mineral acids. From 1914 to 1930, Van Slyke and others established our acid base principles. They recognised that carbonic acid converts into bicarbonate all non-volatile mineral bases not bound by mineral acids and determined therefore that bicarbonate represents the alkaline reserve of the body and should be a physiological constant. They showed that standard bicarbonate is a good measure of acidosis caused by increased production or decreased elimination of organic acids. However, they recognised that bicarbonate improved low plasma bicarbonate but not high urine acid excretion in diabetic ketoacidosis, and that increasing pCO2 caused chloride to shift into cells raising plasma titratable alkali. Both indicate that minerals influence pH. In 1945 Darrow showed that hyperchloraemic metabolic acidosis in preterm infants fed milk with 5.7 mmol of chloride and 2.0 mmol of sodium per 100 kcal was caused by retention of chloride in excess of sodium. Similar findings were made but not recognised in later studies of metabolic acidosis in preterm infants. Shohl in 1921 and Kildeberg in 1978 presented the theory that carbonic and organic acids are neutralised by mineral base, where mineral base is the excess of mineral cations over anions and organic acid is the difference between mineral base, bicarbonate and protein anion. The degree of metabolic acidosis measured as base excess is determined by deviation in both mineral base and organic acid from normal.

  19. Chip-based sequencing nucleic acids

    Energy Technology Data Exchange (ETDEWEB)

    Beer, Neil Reginald

    2014-08-26

    A system for fast DNA sequencing by amplification of genetic material within microreactors, denaturing, demulsifying, and then sequencing the material, while retaining it in a PCR/sequencing zone by a magnetic field. One embodiment includes sequencing nucleic acids on a microchip that includes a microchannel flow channel in the microchip. The nucleic acids are isolated and hybridized to magnetic nanoparticles or to magnetic polystyrene-coated beads. Microreactor droplets are formed in the microchannel flow channel. The microreactor droplets containing the nucleic acids and the magnetic nanoparticles are retained in a magnetic trap in the microchannel flow channel and sequenced.

  20. Chip-based sequencing nucleic acids

    Science.gov (United States)

    Beer, Neil Reginald

    2014-08-26

    A system for fast DNA sequencing by amplification of genetic material within microreactors, denaturing, demulsifying, and then sequencing the material, while retaining it in a PCR/sequencing zone by a magnetic field. One embodiment includes sequencing nucleic acids on a microchip that includes a microchannel flow channel in the microchip. The nucleic acids are isolated and hybridized to magnetic nanoparticles or to magnetic polystyrene-coated beads. Microreactor droplets are formed in the microchannel flow channel. The microreactor droplets containing the nucleic acids and the magnetic nanoparticles are retained in a magnetic trap in the microchannel flow channel and sequenced.

  1. Synthesis of variants of Marfey's reagent having d-amino acids as chiral auxiliaries and liquid-chromatographic enantioseparation of (RS)-Mexiletine in spiked plasma: assessment and comparison with L-amino acid analogs.

    Science.gov (United States)

    Bhushan, Ravi; Vashistha, Vinod Kumar

    2015-01-30

    Five d-amino acids have been used for the first time to synthesize chiral derivatizing reagents (as variants of Marfey's reagent) by nucleophilic displacement of one of the fluorine atoms in 1,5-difluoro-2,4-dinitrobenzene as against the literature reports on application of only l-amino acids or their amides as chiral auxiliaries in dinitrobenzene (DNB) moiety. Five other DNB based reagents were also prepared by nucleophilic substitution of fluorine atom with the set of the same amino acids in l-configuration, as chiral auxiliaries. These reagents were characterized and used for synthesis of diastereomers of (RS)-Mexiletine spiked in human plasma. Diastereomers were synthesized employing microwave irradiation and were separated on reversed-phase C18 column. Performance of the two types of chiral derivatizing reagents was compared. The reagents containing d-amino acids provided enhanced separation of diastereomers than those containing l-amino acids. The best resolution was obtained using mobile phase consisting of acetonitrile and 0.1% trifluoroacetic acid in gradient mode. The detection was carried out at 340nm. The method so developed was validated for linearity, accuracy and precision. The limit of quantitation was found to be approximately 25.2ngmL(-1) in human plasma.

  2. Proton exchange between oxymethyl radical and acids and bases: semiempirical quantum-chemical study

    Directory of Open Access Journals (Sweden)

    Irina Pustolaikina

    2016-12-01

    Full Text Available The reactions with proton participation are widely represented in the analytical, technological and biological chemistry. Quantum-chemical study of the exchange processes in hydrogen bonding complexes will allow us to achieve progress in the understanding of the elementary act mechanism of proton transfer in hydrogen bonding chain as well as the essence of the acid-base interactions. Oxymethyl radical •CH2ОН is small in size and comfortable as a model particle that well transmits protolytic properties of paramagnetic acids having more complex structure. Quantum-chemical modeling of proton exchange reaction oxymethyl radical ∙CH2OH and its diamagnetic analog CH3OH with amines, carboxylic acids and water was carried out using UAM1 method with the help of Gaussian-2009 program. QST2 method was used for the search of transition state, IRC procedure was applied for the calculation of descents along the reaction coordinate. The difference in the structure of transition states of ∙CH2OH/ CH3OH with bases and acids has been shown. It has been confirmed that in the case of bases, consecutive proton exchange mechanism was fixed, and in the case of complexes with carboxylic acids parallel proton exchange mechanism was fixed. The similarity in the reaction behavior of paramagnetic and diamagnetic systems in the proton exchange has been found. It was suggested that the mechanism of proton exchange reaction is determined by the structure of the hydrogen bonding cyclic complex, which is, in turn, depends from the nature of the acid-base interactions partners.

  3. Geometric Patterns for Neighboring Bases Near the Stacked State in Nucleic Acid Strands.

    Science.gov (United States)

    Sedova, Ada; Banavali, Nilesh K

    2017-03-14

    Structural variation in base stacking has been analyzed frequently in isolated double helical contexts for nucleic acids, but not as often in nonhelical geometries or in complex biomolecular environments. In this study, conformations of two neighboring bases near their stacked state in any environment are comprehensively characterized for single-strand dinucleotide (SSD) nucleic acid crystal structure conformations. An ensemble clustering method is used to identify a reduced set of representative stacking geometries based on pairwise distances between select atoms in consecutive bases, with multiple separable conformational clusters obtained for categories divided by nucleic acid type (DNA/RNA), SSD sequence, stacking face orientation, and the presence or absence of a protein environment. For both DNA and RNA, SSD conformations are observed that are either close to the A-form, or close to the B-form, or intermediate between the two forms, or further away from either form, illustrating the local structural heterogeneity near the stacked state. Among this large variety of distinct conformations, several common stacking patterns are observed between DNA and RNA, and between nucleic acids in isolation or in complex with proteins, suggesting that these might be stable stacking orientations. Noncanonical face/face orientations of the two bases are also observed for neighboring bases in the same strand, but their frequency is much lower, with multiple SSD sequences across categories showing no occurrences of such unusual stacked conformations. The resulting reduced set of stacking geometries is directly useful for stacking-energy comparisons between empirical force fields, prediction of plausible localized variations in single-strand structures near their canonical states, and identification of analogous stacking patterns in newly solved nucleic acid containing structures.

  4. Ionisation constants of inorganic acids and bases in aqueous solution

    CERN Document Server

    Perrin, D D

    2013-01-01

    Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution, Second Edition provides a compilation of tables that summarize relevant data recorded in the literature up to the end of 1980 for the ionization constants of inorganic acids and bases in aqueous solution. This book includes references to acidity functions for strong acids and bases, as well as details about the formation of polynuclear species. This text then explains the details of each column of the tables, wherein column 1 gives the name of the substance and the negative logarithm of the ionization constant and column 2

  5. 基于五光谱TDICCD的模拟信号发生器设计%Design of Analog Signal Generator Based on Five-spectral TDICCD

    Institute of Scientific and Technical Information of China (English)

    王旭; 刘正敏; 樊奔; 何志宽

    2014-01-01

    首先介绍了延迟积分电荷耦合器件(TDICCD)的基本原理,并根据某高分辨率多光谱航天相机定制的一款五光谱TDICCD的输出特性,设计了一种基于五光谱TDICCD的模拟信号发生器,给出了该模拟信号发生器的系统组成,包括图像处理电路、数模转换电路和模拟信号滤波电路。最后通过测试验证了该系统的信号波形、信号噪声和输出图像都满足设计要求,其输出的16通道模拟五光谱TDICCD信号频率可以达到20MHz,噪声控制在10mV以内,具有高精度、多通道和低噪声等特点。目前该模拟信号发生器已成功应用到新一代高分辨率多光谱TDICCD相机成像电路系统的研制中。%The paper introduces the principle of TDICCD firstly, and then designs an analog signal generator based on five-spectral TDICCD, according to the output characteristic of five-spectral TDICCD customized by a high resolution multi-spectral TDICCD camera. Analog signal generator consists of image processing circuit, digital-to-analog conversion circuit and analog signal filter circuit. Finally, verified by the system of signal, signal to noise ratio and the output images meet the design requirements. The system has the characteristics of high precision, multi-channel and low noise, whose 16 channels can analog five-spectral TDICCD signal frequency up to 20MHz and the signal to noise ratio is less than 10mV. The analog signal generator has been successfully applied in the development of imaging circuit system of the new generation high resolution multi-spectral TDICCD camera.

  6. Physico-Chemical, and Sensory Properties of Soy Based Gouda Cheese Analog Made from Different Concentration of Fat, Sodium Citrate and Various Cheese Starter Cultures

    Directory of Open Access Journals (Sweden)

    Abu Amar

    2013-04-01

    Full Text Available Gouda cheese analog (GCA was made using soy protein isolate (SPI, skim milk powder (SMP, fat (palm fat and butter fat, and water (W at optimal ratio of SPI : SMP : F : W = 14 : 6 : 20 : 60. The effects of butter fat, sodium citrate, and cheese starter culture on the sensory properties of ripened product were assessed by preference test, hedonic test, and the texture profile analysis (TPA of GCA. The free fatty acids, water-soluble nitrogen, and reduction in pH value of progel were also measured. The use of 100% butter fat (BF produced strong Gouda flavor. It could be due to the fatty acids content in BF; in contrast, product with 100% palm fat (PF produced tasteless GCA. It might be due to fatty acids content in PF, middle, and long chain fatty acids. Single cheese starter culture could not develop Gouda flavor during ripening. The use of mixed fat (50% BF and 50% PF and mixed cheese starter culture together with Brevibacterium linens developed a suitable characteristic flavor of Gouda product during ripening. The addition of 0.5% sodium citrate could improve the flavor; nevertheless, it reduced the stability of texture.

  7. A Closer Look at Acid-Base Olfactory Titrations

    Science.gov (United States)

    Neppel, Kerry; Oliver-Hoyo, Maria T.; Queen, Connie; Reed, Nicole

    2005-01-01

    Olfactory titrations using raw onions and eugenol as acid-base indicators are reported. An in-depth investigation on olfactory titrations is presented to include requirements for potential olfactory indicators and protocols for using garlic, onions, and vanillin as acid-base olfactory indicators are tested.

  8. What is the Ultimate Goal in Acid-Base Regulation?

    Science.gov (United States)

    Balakrishnan, Selvakumar; Gopalakrishnan, Maya; Alagesan, Murali; Prakash, E. Sankaranarayanan

    2007-01-01

    It is common to see chapters on acid-base physiology state that the goal of acid-base regulatory mechanisms is to maintain the pH of arterial plasma and not arterial PCO [subscript 2] (Pa[subscript CO[subscript 2

  9. The Roles of Acids and Bases in Enzyme Catalysis

    Science.gov (United States)

    Weiss, Hilton M.

    2007-01-01

    Many organic reactions are catalyzed by strong acids or bases that protonate or deprotonate neutral reactants leading to reactive cations or anions that proceed to products. In enzyme reactions, only weak acids and bases are available to hydrogen bond to reactants and to transfer protons in response to developing charges. Understanding this…

  10. Disorders of Acid-Base Balance: New Perspectives.

    Science.gov (United States)

    Seifter, Julian L; Chang, Hsin-Yun

    2017-01-01

    Disorders of acid-base involve the complex interplay of many organ systems including brain, lungs, kidney, and liver. Compensations for acid-base disturbances within the brain are more complete, while limitations of compensations are more apparent for most systemic disorders. However, some of the limitations on compensations are necessary to survival, in that preservation of oxygenation, energy balance, cognition, electrolyte, and fluid balance are connected mechanistically. This review aims to give new and comprehensive perspective on understanding acid-base balance and identifying associated disorders. All metabolic acid-base disorders can be approached in the context of the relative losses or gains of electrolytes or a change in the anion gap in body fluids. Acid-base and electrolyte balance are connected not only at the cellular level but also in daily clinical practice. Urine chemistry is essential to understanding electrolyte excretion and renal compensations. Many constructs are helpful to understand acid-base, but these models are not mutually exclusive. Electroneutrality and the close interconnection between electrolyte and acid-base balance are important concepts to apply in acid-base diagnoses. All models have complexity and shortcuts that can help in practice. There is no reason to dismiss any of the present constructs, and there is benefit in a combined approach.

  11. A new representation of acid-base disturbances

    NARCIS (Netherlands)

    M. Hekking (Marcel); E.S. Gelsema; J. Lindemans (Jan)

    1994-01-01

    textabstractThe acid-base status of intensive care patients is monitored on the basis of three quantities. The graphical representation which may be of help for the monitoring task is therefore cumbersome. The classical Siggaard-Andersen acid-base chart is such a representation, but it is only suite

  12. The Roles of Acids and Bases in Enzyme Catalysis

    Science.gov (United States)

    Weiss, Hilton M.

    2007-01-01

    Many organic reactions are catalyzed by strong acids or bases that protonate or deprotonate neutral reactants leading to reactive cations or anions that proceed to products. In enzyme reactions, only weak acids and bases are available to hydrogen bond to reactants and to transfer protons in response to developing charges. Understanding this…

  13. Connecting Acids and Bases with Encapsulation... and Chemistry with Nanotechnology

    Science.gov (United States)

    Criswell, Brett

    2007-01-01

    The features and the development of various new acids and bases activity sets that combines chemistry with nanotechnology are being described. These sets lead to the generation of many nanotechnology-based pharmaceuticals for the treatment of various diseases.

  14. Connecting Acids and Bases with Encapsulation... and Chemistry with Nanotechnology

    Science.gov (United States)

    Criswell, Brett

    2007-01-01

    The features and the development of various new acids and bases activity sets that combines chemistry with nanotechnology are being described. These sets lead to the generation of many nanotechnology-based pharmaceuticals for the treatment of various diseases.

  15. Firing Efficiency of Cluster Bomb Based on Method of Analogy%基于类比法的子母弹射击效率评定研究

    Institute of Scientific and Technical Information of China (English)

    殷培江; 李君; 张立生

    2012-01-01

    The method of analogy is a familiar logistic organon used in the mess of research domain, but it's rarely used in evaluation martial category. The firing efficiency of cluster bomb based on method of analogy have many advantage, for instance it is briefness, practicability, economy, and convenient for largely reckon. The paper builds the evaluation index system of the firing efficiency with cluster bomb, we found the comparable from cluster bomb to another ammunition in classical model, build the mathematics model based on method of analogy in the next place. The paper serve as an example of several emblematic targets, and display status of firing efficiency with several emblematic targets used the radar chart, we have compared the conclusions with method of analogy and emulation mode, validate the firing efficiency of cluster bomb based on method of analogy is feasible.%类比法是一种较为常见的逻辑推理方法,在各研究领域均有应用,但在军事评估领域却应用甚少.基于类比法的子母弹射击效率评定具有简单、实用、经济、便于大量计算等优点.根据子母弹与传统弹药在射击效率评定过程中的相似性,在经典毁伤评估模型的基础上,通过类比法建立字母弹的射击效率评定模型.列举了几种典型目标,并以子母弹的类比法模型进行射击效率评定,最后将类比法所得结论与目标仿真法的结论反映在雷达图上,通过数据比对验证了类比法对子母弹射击效率评定的可行性.

  16. 基于Aspen Plus的克劳斯硫回收过程模拟%Analog of ClausSulfur Recovery Process Based on Aspen Plus

    Institute of Scientific and Technical Information of China (English)

    林发现; 丁玲; 陈延林; 李繁荣; 师慧灵; 邹隐文

    2011-01-01

    Adopting Aspen Plus process analog calculation software,process flow for Claus sulfur recovery was simulated,simulated data was good coincident with the data demarcated by analog software used specially for sulfur recovery;on that basis,author has studied the influence of Claus key data on process flow by use of Aspen Plus modular analysis function,its conclusion was coincident with practical production process;result indicates that it has optimizing role for both design calculation and production operation based on the Claus sulfur recovery process analog.%采用Aspen P lus工艺模拟计算软件模拟了克劳斯硫回收工艺过程,模拟数据与硫回收专用模拟软件的标定数据吻合较好;在此基础上,利用Aspen P lus模块化分析功能,研究了克劳斯工艺的关键数据对工艺过程的影响,其结论与实际生产过程相符合;结果表明,基于Aspen P lus的克劳斯硫回收过程模拟,对设计计算和生产操作均具有优化作用。

  17. Total synthesis of dihydrolysergic acid and dihydrolysergol: development of a divergent synthetic strategy applicable to rapid assembly of D-ring analogs

    Science.gov (United States)

    Lee, Kiyoun; Poudel, Yam B.; Glinkerman, Christopher M.; Boger, Dale L.

    2015-01-01

    The total syntheses of dihydrolysergic acid and dihydrolysergol are detailed based on a Pd(0)-catalyzed intramolecular Larock indole cyclization for the preparation of the embedded tricyclic indole (ABC ring system) and a subsequent powerful inverse electron demand Diels–Alder reaction of 5-carbomethoxy-1,2,3-triazine with a ketone-derived enamine for the introduction of a functionalized pyridine, serving as the precursor for a remarkably diastereoselective reduction to the N-methylpiperidine D-ring. By design, the use of the same ketone-derived enamine and a set of related complementary heterocyclic azadiene [4 + 2] cycloaddition reactions permitted the late stage divergent preparation of a series of alternative heterocyclic derivatives not readily accessible by more conventional approaches. PMID:26273113

  18. Computer-guided design, synthesis, and protein kinase C affinity of a new salicylate-based class of bryostatin analogs.

    Science.gov (United States)

    Wender, Paul A; Nakagawa, Yu; Near, Katherine E; Staveness, Daryl

    2014-10-03

    Bryostatin 1 is in clinical trials for the treatment of cancer and Alzheimer's disease and is a candidate for a first-in-class approach to HIV/AIDS eradication. It is neither readily available nor optimally suited for clinical use. Using a function oriented synthesis strategy, a new class of bryostatin-inspired analogs was designed with a simplified salicylate-derived subunit, enabling step-economical synthesis (23 total steps) of agents exhibiting bryostatin-like affinity to protein kinase C (PKC).

  19. Selection of the optimum combination of responses for Wave Buoy Analogy - An approach based on local sensitivity analysis

    DEFF Research Database (Denmark)

    Montazeri, Najmeh; Nielsen, Ulrik Dam; Jensen, Jørgen Juncher

    2016-01-01

    One method to estimate the wave spectrum onboard ships is to use measured ship responses. In this method, known also as Wave Buoy Analogy, amongst various responses that are available from sensor measurements, a couple of responses (at least three) are usually utilized. Selec-tion of the best...... combination of ship responses is important. Optimally, this selection should not be implemented manually in onboard applications. Therefore, availability of an automatic response selection procedure would be a great advantage for decision support. In this paper, a local sensitivity analysis is applied...

  20. Quantification of Lewis acid induced Brønsted acidity of protogenic Lewis bases.

    Science.gov (United States)

    Lathem, A Paige; Heiden, Zachariah M

    2017-05-09

    Proton transfer promoted by the coordination of protogenic Lewis bases to a Lewis acid is a critical step in catalytic transformations. Although the acidification of water upon coordination to a Lewis acid has been known for decades, no attempts have been made to correlate the Brønsted acidity of the coordinated water molecule with Lewis acid strength. To probe this effect, the pKa's (estimated error of 1.3 pKa units) in acetonitrile of ten protogenic Lewis bases coordinated to seven Lewis acids containing Lewis acidities varying 70 kcal mol(-1), were computed. To quantify Lewis acid strength, the ability to transfer a hydride (hydride donor ability) from the respective main group hydride was used. Coordination of a Lewis acid to water increased the acidity of the bound water molecule between 20 and 50 pKa units. A linear correlation exhibiting a 2.6 pKa unit change of the Lewis acid-water adduct per ten kcal mol(-1) change in hydride donor ability of the respective main group hydride was obtained. For the ten protogenic Lewis bases studied, the coordinated protogenic Lewis bases were acidified between 10 and 50 pKa units. On average, a ten kcal mol(-1) change in hydride donor ability of the respective main group hydride resulted in about a 2.8 pKa unit change in the Brønsted acidity of the Lewis acid-Lewis base adducts. Since attempts to computationally investigate the pKa of main group dihydrogen complexes were unsuccessful, experimental determination of the first reported pKa of a main group dihydrogen complex is described. The pKa of H2-B(C6F5)3 was determined to be 5.8 ± 0.2 in acetonitrile.

  1. Analog and hybrid computing

    CERN Document Server

    Hyndman, D E

    2013-01-01

    Analog and Hybrid Computing focuses on the operations of analog and hybrid computers. The book first outlines the history of computing devices that influenced the creation of analog and digital computers. The types of problems to be solved on computers, computing systems, and digital computers are discussed. The text looks at the theory and operation of electronic analog computers, including linear and non-linear computing units and use of analog computers as operational amplifiers. The monograph examines the preparation of problems to be deciphered on computers. Flow diagrams, methods of ampl

  2. Efficiency and hardware comparison of analog control-based and digital control-based 70 W two-stage power factor corrector and DC-DC converters

    DEFF Research Database (Denmark)

    Török, Lajos; Munk-Nielsen, Stig

    2011-01-01

    A comparison of an analog and a digital controller driven 70 W two-stage power factor corrector converter is presented. Both controllers are operated in average current-mode-control for the PFC and peak current control for the DC-DC converter. Digital controller design and converter modeling...... is described. Results show that digital control can compete with the analog one in efficiency, PFC and THD....

  3. Environmental temperature effect on the far-infrared absorption features of aromatic-based Titan's aerosol analogs

    Science.gov (United States)

    Gautier, Thomas; Trainer, Melissa G.; Loeffler, Mark J.; Sebree, Joshua A.; Anderson, Carrie M.

    2017-01-01

    Benzene detection has been reported in Titan's atmosphere both in the stratosphere at ppb levels by remote sensing (Coustenis et al., 2007; Vinatier et al., 2007) and in the thermosphere at ppm levels by the Cassini's Ion and Neutral Mass Spectrometer (Waite et al., 2007). This detection supports the idea that aromatic and heteroaromatic reaction pathways may play an important role in Titan's atmospheric chemistry, especially in the formation of aerosols. Indeed, aromatic molecules are easily dissociated by ultraviolet radiation and can therefore contribute significantly to aerosol formation. It has been shown recently that aerosol analogs produced from a gas mixture containing a low concentration of aromatic and/or heteroaromatic molecules (benzene, naphthalene, pyridine, quinoline and isoquinoline) have spectral signatures below 500 cm-1, a first step towards reproducing the aerosol spectral features observed by Cassini's Composite InfraRed Spectrometer (CIRS) in the far infrared (Anderson and Samuelson 2011, and references therein). In this work we investigate the influence of environmental temperature on the absorption spectra of such aerosol samples, simulating the temperature range to which aerosols, once formed, are exposed during their transport through Titan's stratosphere. Our results show that environmental temperature does not have any major effect on the spectral shape of these aerosol analogs in the far-infrared, which is consistent with the CIRS observations.

  4. Synchronization sampling method based on delta-sigma analog-digital converter for underwater towed array system

    Science.gov (United States)

    Jiang, Jia-Jia; Duan, Fa-Jie; Li, Yan-Chao; Hua, Xiang-Ning

    2014-03-01

    Synchronization sampling is very important in underwater towed array system where every acquisition node (AN) samples analog signals by its own analog-digital converter (ADC). In this paper, a simple and effective synchronization sampling method is proposed to ensure synchronized operation among different ANs of the underwater towed array system. We first present a master-slave synchronization sampling model, and then design a high accuracy phase-locked loop to synchronize all delta-sigma ADCs to a reference clock. However, when the master-slave synchronization sampling model is used, both the time-delay (TD) of messages traveling along the wired transmission medium and the jitter of the clocks will bring out synchronization sampling error (SSE). Therefore, a simple method is proposed to estimate and compensate the TD of the messages transmission, and then another effective method is presented to overcome the SSE caused by the jitter of the clocks. An experimental system with three ANs is set up, and the related experimental results verify the validity of the synchronization sampling method proposed in this paper.

  5. Salmonella enterica MTAN at 1.36 Å resolution: a structure-based design of tailored transition state analogs.

    Science.gov (United States)

    Haapalainen, Antti M; Thomas, Keisha; Tyler, Peter C; Evans, Gary B; Almo, Steven C; Schramm, Vern L

    2013-06-04

    Accumulation of 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH) in bacteria disrupts the S-adenosylmethionine pool to alter biological methylations, synthesis of polyamines, and production of quorum-sensing molecules. Bacterial metabolism of MTA and SAH depends on MTA/SAH nucleosidase (MTAN), an enzyme not present in humans and a target for quorum sensing because MTAN activity is essential for synthesis of autoinducer-2 molecules. Crystals of Salmonella enterica MTAN with product and transition state analogs of MTA and SAH explain the structural contacts causing pM binding affinity for the inhibitor and reveal a "water-wire" channel for the catalytic nucleophile. The crystal structure shows an extension of the binding pocket filled with polyethylene glycol. We exploited this discovery by the design and synthesis of tailored modifications of the currently existing transition state analogs to fill this site. This site was not anticipated in MTAN structures. Tailored inhibitors with dissociation constants of 5 to 15 pM are characterized.

  6. Development of molecular docking-based binding energy to predict the joint effect of BPA and its analogs.

    Science.gov (United States)

    Zhang, Hong-Chang; Hu, Xia-Lin; Yin, Da-Qiang; Lin, Zhi-Fen

    2011-04-01

    A general proposal for predicting the joint effect of endocrine disrupting chemicals by examining binding energy models was developed in this study. 2,2-bis(4-hydroxyphenyl)propane (BPA) and 11 of its analogs were chosen, and the estrogenic activity of each compound was measured by determining its EC50 value using a recombinant gene yeast assay. Binding energies (BEs) were calculated using Surflex-Docking software. The analysis of the relationship between EC50 values and BEs showed that there is a linear correlation between the BEs and EC50 values. Furthermore, the analysis of the given binary and quaternary mixtures of BPA and three of its analogs showed that the joint effects of the mixtures were affected by the proportions of the chemicals in each mixture and their relative binding energy. The correlation between the joint effects of mixtures and the binding energy of the individual compounds has been described using one formula, which can be used to predict the joint effects of other mixtures.

  7. General base-general acid catalysis by terpenoid cyclases.

    Science.gov (United States)

    Pemberton, Travis A; Christianson, David W

    2016-07-01

    Terpenoid cyclases catalyze the most complex reactions in biology, in that more than half of the substrate carbon atoms often undergo changes in bonding during the course of a multistep cyclization cascade that proceeds through multiple carbocation intermediates. Many cyclization mechanisms require stereospecific deprotonation and reprotonation steps, and most cyclization cascades are terminated by deprotonation to yield an olefin product. The first bacterial terpenoid cyclase to yield a crystal structure was pentalenene synthase from Streptomyces exfoliatus UC5319. This cyclase generates the hydrocarbon precursor of the pentalenolactone family of antibiotics. The structures of pentalenene synthase and other terpenoid cyclases reveal predominantly nonpolar active sites typically lacking amino acid side chains capable of serving general base-general acid functions. What chemical species, then, enables the Brønsted acid-base chemistry required in the catalytic mechanisms of these enzymes? The most likely candidate for such general base-general acid chemistry is the co-product inorganic pyrophosphate. Here, we briefly review biological and nonbiological systems in which phosphate and its derivatives serve general base and general acid functions in catalysis. These examples highlight the fact that the Brønsted acid-base activities of phosphate derivatives are comparable to the Brønsted acid-base activities of amino acid side chains.

  8. Carbon-based strong solid acid for cornstarch hydrolysis

    Science.gov (United States)

    Nata, Iryanti Fatyasari; Irawan, Chairul; Mardina, Primata; Lee, Cheng-Kang

    2015-10-01

    Highly sulfonated carbonaceous spheres with diameter of 100-500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO3H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO3H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst.

  9. Effect of benzoic acid supplementation on acid-base status and mineralmetabolism in catheterized growing pigs

    DEFF Research Database (Denmark)

    Nørgaard, Jan Værum; Fernández, José Adalberto; Sørensen, Kristina Ulrich;

    2010-01-01

    Benzoic acid (BA) in diets for growing pigs results in urinary acidification and reduced ammonia emission. The objective was to study the impact of BA supplementation on the acid-base status and mineral metabolism in pigs. Eight female 50-kg pigs, fitted with a catheter in the abdominal aorta, were...

  10. Facile syntheses of dissymmetric ferrocene-functionalized Lewis acids and acid-base pairs.

    Science.gov (United States)

    Morgan, Ian R; Di Paolo, Angela; Vidovic, Dragoslav; Fallis, Ian A; Aldridge, Simon

    2009-12-21

    A facile synthetic approach is reported for the synthesis of dissymmetric 1,2-ferrocenediyl Lewis acids and mixed acid-base pairs including the first example of a 1-phosphino-2-borylferrocene; the use of non-racemic electrophiles allows for the isolation of single diastereomer products.

  11. A novel method based solely on FPGA units enabling measurement of time and charge of analog signals in Positron Emission Tomography

    CERN Document Server

    Pałka, M; Białas, P; Czerwiński, E; Kapłon, Ł; Kochanowski, A; Korcyl, G; Kowal, J; Kowalski, P; Kozik, T; Krzemień, W; Molenda, M; Moskal, P; Niedźwiecki, Sz; Pawlik, M; Raczyński, L; Rudy, Z; Salabura, P; Sharma, N G; Silarski, M; Słomski, A; Smyrski, J; Strzelecki, A; Wiślicki, W; Zieliński, M; Zoń, N

    2013-01-01

    This article presents a novel technique for precise measurement of time and charge based solely on FPGA (Field Programmable Gate Array) device and few satellite discrete electronic components used in Positron Emission Tomography (PET). Described approach simplifies electronic circuits, reduces the power consumption, lowers costs, merges front-end electronics with digital electronics and also makes more compact final design. Furthermore, it allows to measure time when analog signals cross a reference voltage at different threshold levels with a very high precision of $\\sim$ 10ps (rms) and thus enables sampling of signals in a voltage domain.

  12. Polymerization of amino acids containing nucleotide bases

    Science.gov (United States)

    Ben Cheikh, Azzouz; Orgel, Leslie E.

    1990-01-01

    The nucleoamino acids 1-(3'-amino,3'-carboxypropyl)uracil (3) and 9-(3'-amino,3'-carboxypropyl)adenine (4) have been prepared as (L)-en-antiomers and as racemic mixtures. When 3 or 4 is suspended in water and treated with N,N'-carbon-yldiimidazole, peptides are formed in good yield. The products formed from the (L)-enantiomers are hydrolyzed to the monomeric amino acids by pronase. Attempts to improve the efficiency of these oligomerizations by including a polyuridylate template in the reaction mixture were not successful. Similarly, oligomers derived from the (L)-enantiomer of 3 did not act as templates to facilitate the oligomerization of 4.

  13. Carbon-based strong solid acid for cornstarch hydrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Nata, Iryanti Fatyasari, E-mail: yanti_tkunlam@yahoo.com [Chemical Engineering Study Program, Faculty of Engineering, Lambung Mangkurat University, Jl. A. Yani Km. 36 Banjarbaru, South Kalimantan 70714 (Indonesia); Irawan, Chairul; Mardina, Primata [Chemical Engineering Study Program, Faculty of Engineering, Lambung Mangkurat University, Jl. A. Yani Km. 36 Banjarbaru, South Kalimantan 70714 (Indonesia); Lee, Cheng-Kang, E-mail: cklee@mail.ntust.edu.tw [Department of Chemical Engineering, National Taiwan University of Science and Technology, 43 Keelung Rd. Sec.4, Taipei 106, Taiwan (China)

    2015-10-15

    Highly sulfonated carbonaceous spheres with diameter of 100–500 nm can be generated by hydrothermal carbonization of glucose in the presence of hydroxyethylsulfonic acid and acrylic acid at 180 °C for 4 h. The acidity of the prepared carbonaceous sphere C4-SO{sub 3}H can reach 2.10 mmol/g. It was used as a solid acid catalyst for the hydrolysis of cornstarch. Total reducing sugar (TRS) concentration of 19.91 mg/mL could be obtained by hydrolyzing 20 mg/mL cornstarch at 150 °C for 6 h using C4-SO{sub 3}H as solid acid catalyst. The solid acid catalyst demonstrated good stability that only 9% decrease in TRS concentration was observed after five repeat uses. The as-prepared carbon-based solid acid catalyst can be an environmentally benign replacement for homogeneous catalyst. - Highlights: • Carbon solid acid was successfully prepared by one-step hydrothermal carbonization. • The acrylic acid as monomer was effectively reduce the diameter size of particle. • The solid acid catalyst show good catalytic performance of starch hydrolysis. • The solid acid catalyst is not significantly deteriorated after repeated use.

  14. Nucleic Acid--Based Nanodevices in Biological Imaging

    Science.gov (United States)

    Chakraborty, Kasturi; Veetil, Aneesh T.

    2017-01-01

    The nanoscale engineering of nucleic acids has led to exciting molecular technologies for high-end biological imaging. The predictable base pairing, high programmability, and superior new chemical and biological methods used to access nucleic acids with diverse lengths and in high purity, coupled with computational tools for their design, have allowed the creation of a stunning diversity of nucleic acid--based nanodevices. Given their biological origin, such synthetic devices have a tremendous capacity to interface with the biological world, and this capacity lies at the heart of several nucleic acid--based technologies that are finding applications in biological systems. We discuss these diverse applications and emphasize the advantage, in terms of physicochemical properties, that the nucleic acid scaffold brings to these contexts. As our ability to engineer this versatile scaffold increases, its applications in structural, cellular, and organismal biology are clearly poised to massively expand. PMID:27294440

  15. Nucleic Acid-Based Nanodevices in Biological Imaging.

    Science.gov (United States)

    Chakraborty, Kasturi; Veetil, Aneesh T; Jaffrey, Samie R; Krishnan, Yamuna

    2016-06-02

    The nanoscale engineering of nucleic acids has led to exciting molecular technologies for high-end biological imaging. The predictable base pairing, high programmability, and superior new chemical and biological methods used to access nucleic acids with diverse lengths and in high purity, coupled with computational tools for their design, have allowed the creation of a stunning diversity of nucleic acid-based nanodevices. Given their biological origin, such synthetic devices have a tremendous capacity to interface with the biological world, and this capacity lies at the heart of several nucleic acid-based technologies that are finding applications in biological systems. We discuss these diverse applications and emphasize the advantage, in terms of physicochemical properties, that the nucleic acid scaffold brings to these contexts. As our ability to engineer this versatile scaffold increases, its applications in structural, cellular, and organismal biology are clearly poised to massively expand.

  16. Teaching acid/base physiology in the laboratory

    DEFF Research Database (Denmark)

    Friis, Ulla G; Plovsing, Ronni; Hansen, Klaus;

    2010-01-01

    Acid/base homeostasis is one of the most difficult subdisciplines of physiology for medical students to master. A different approach, where theory and practice are linked, might help students develop a deeper understanding of acid/base homeostasis. We therefore set out to develop a laboratory...... exercise in acid/base physiology that would provide students with unambiguous and reproducible data that clearly would illustrate the theory in practice. The laboratory exercise was developed to include both metabolic acidosis and respiratory alkalosis. Data were collected from 56 groups of medical...

  17. Respiratory Acid-Base Disorders in the Critical Care Unit.

    Science.gov (United States)

    Hopper, Kate

    2017-03-01

    The incidence of respiratory acid-base abnormalities in the critical care unit (CCU) is unknown, although respiratory alkalosis is suspected to be common in this population. Abnormal carbon dioxide tension can have many physiologic effects, and changes in Pco2 may have a significant impact on outcome. Monitoring Pco2 in CCU patients is an important aspect of critical patient assessment, and identification of respiratory acid-base abnormalities can be valuable as a diagnostic tool. Treatment of respiratory acid-base disorders is largely focused on resolution of the primary disease, although mechanical ventilation may be indicated in cases with severe respiratory acidosis. Published by Elsevier Inc.

  18. Phase-Based Binocular Perception of Motion in Depth: Cortical-Like Operators and Analog VLSI Architectures

    Science.gov (United States)

    Sabatini, Silvio P.; Solari, Fabio; Cavalleri, Paolo; Bisio, Giacomo Mario

    2003-12-01

    We present a cortical-like strategy to obtain reliable estimates of the motions of objects in a scene toward/away from the observer (motion in depth), from local measurements of binocular parameters derived from direct comparison of the results of monocular spatiotemporal filtering operations performed on stereo image pairs. This approach is suitable for a hardware implementation, in which such parameters can be gained via a feedforward computation (i.e., collection, comparison, and punctual operations) on the outputs of the nodes of recurrent VLSI lattice networks, performing local computations. These networks act as efficient computational structures for embedded analog filtering operations in smart vision sensors. Extensive simulations on both synthetic and real-world image sequences prove the validity of the approach that allows to gain high-level information about the 3D structure of the scene, directly from sensorial data, without resorting to explicit scene reconstruction.

  19. Phase-Based Binocular Perception of Motion in Depth: Cortical-Like Operators and Analog VLSI Architectures

    Directory of Open Access Journals (Sweden)

    Silvio P. Sabatini

    2003-06-01

    Full Text Available We present a cortical-like strategy to obtain reliable estimates of the motions of objects in a scene toward/away from the observer (motion in depth, from local measurements of binocular parameters derived from direct comparison of the results of monocular spatiotemporal filtering operations performed on stereo image pairs. This approach is suitable for a hardware implementation, in which such parameters can be gained via a feedforward computation (i.e., collection, comparison, and punctual operations on the outputs of the nodes of recurrent VLSI lattice networks, performing local computations. These networks act as efficient computational structures for embedded analog filtering operations in smart vision sensors. Extensive simulations on both synthetic and real-world image sequences prove the validity of the approach that allows to gain high-level information about the 3D structure of the scene, directly from sensorial data, without resorting to explicit scene reconstruction.

  20. Understanding the link between circumferential dikes and eruptive fissures around calderas based on numerical and analog models

    Science.gov (United States)

    Corbi, Fabio; Rivalta, Eleonora; Pinel, Virginie; Maccaferri, Francesco; Acocella, Valerio

    2016-06-01

    Active calderas are seldom associated with circumferential eruptive fissures, but eroded magmatic complexes reveal widespread circumferential dikes. This suggests that, while the conditions to emplace circumferential dikes are easily met, mechanisms must prevent them from reaching the surface. We explain this discrepancy with experiments of air injection into gelatin shaped as a volcano with caldera. Analog dikes show variable deflection, depending on the competition between overpressure, Pe, and topographic unloading, Pl; when Pl/Pe = 4.8-5.3, the dikes propagate orthogonal to the least compressive stress. Due to the unloading, they become circumferential and stall below the caldera rim; buoyancy is fundamental for the further rise and circumferential fissure development. Numerical models quantitatively constrain the stress orientation within the gelatin, explaining the observed circumferential dikes. Our results explain how dikes propagate below the rim of felsic and mafic calderas, but only in the latter they are prone to feed circumferential fissures.

  1. Design of a reliable PUF circuit based on R-2R ladder digital-to-analog convertor

    Science.gov (United States)

    Pengjun, Wang; Xuelong, Zhang; Yuejun, Zhang; Jianrui, Li

    2015-07-01

    A novel physical unclonable functions (PUF) circuit is proposed, which relies on non-linear characteristic of analog voltage generated by R-2R ladder DAC. After amplifying the deviation signal, the robustness of the DAC-PUF circuit has increased significantly. The DAC-PUF circuit is designed in TSMC 65 nm CMOS technology and the layout occupies 86.06 × 63.56 μm2. Monte Carlo simulation results show that the reliability of the DAC-PUF circuit is above 98% over a comprehensive range of environmental variation, such as temperature and supply voltage. Project supported by the National Natural Science Foundation of China (Nos. 61474068, 61404076, 61274132), the Zhejiang Provincial Natural Science Foundation of China (No. LQ14F040001), and the K. C. Wong Magna Fund in Ningbo University, China.

  2. A new Michaelis-Menten-based kinetic model for transport and phosphorylation of glucose and its analogs in skeletal muscle.

    Science.gov (United States)

    Huang, Hsuan-Ming; Ismail-Beigi, Faramarz; Muzic, Raymond F

    2011-08-01

    A new model is introduced that individually resolves the delivery, transport, and phosphorylation steps of metabolism of glucose and its analogs in skeletal muscle by interpreting dynamic positron emission tomography (PET) data. The model uniquely utilizes information obtained from the competition between glucose and its radiolabeled analogs. Importantly, the model avoids use of a lumped constant which may depend on physiological state. Four basic physiologic quantities constitute our model parameters, including the fraction of total tissue space occupied by interstitial space (f(IS)), a flow-extraction product and interstitial (IS(g)) and intracellular (IC(g)) glucose concentrations. Using the values of these parameters, cellular influx (CI) and efflux (CE) of glucose, glucose phosphorylation rate (PR), and maximal transport (V(G)) and phosphorylation capacities (V(H)) can all be determined. Herein, the theoretical derivation of our model is addressed and characterizes its properties via simulation. Specifically, the model performance is evaluated by simulation of basal and euglycemic hyperinsulinemic (EH) conditions. In fitting the model-generated, synthetic data (including noise), mean estimates of all but IC(g) of the parameter values are within 5% of their values for both conditions. In addition, mean errors of CI, PR, and V(G) are less than 5% whereas those of VH and CE are not. It is concluded that under the conditions tested, the novel model can provide accurate parameter estimates and physiological quantities, except IC(g) and two quantities that are dependent on IC(g), namely CE and VH. However, the ability to estimate IC(g) seems to improve with increases in intracellular glucose concentrations as evidenced by comparing IC(g) estimates under basal vs EH conditions.

  3. Environmentally Benign Bifunctional Solid Acid and Base Catalysts

    NARCIS (Netherlands)

    Elmekawy, A.; Shiju, N.R.; Rothenberg, G.; Brown, D.R.

    2014-01-01

    Solid bifunctional acid-​base catalysts were prepd. in two ways on an amorphous silica support: (1) by grafting mercaptopropyl units (followed by oxidn. to propylsulfonic acid) and aminopropyl groups to the silica surface (NH2-​SiO2-​SO3H)​, and (2) by grafting only aminopropyl groups and then parti

  4. Acid-base transport in pancreas-new challenges

    DEFF Research Database (Denmark)

    Novak, Ivana; Haanes, Kristian Agmund; Wang, Jing

    2013-01-01

    Along the gastrointestinal tract a number of epithelia contribute with acid or basic secretions in order to aid digestive processes. The stomach and pancreas are the most extreme examples of acid (H+) and base (HCO-3) transporters, respectively. Nevertheless, they share the same challenges of tra...

  5. All-optical analog comparator

    Science.gov (United States)

    Li, Pu; Yi, Xiaogang; Liu, Xianglian; Zhao, Dongliang; Zhao, Yongpeng; Wang, Yuncai

    2016-08-01

    An analog comparator is one of the core units in all-optical analog-to-digital conversion (AO-ADC) systems, which digitizes different amplitude levels into two levels of logical ‘1’ or ‘0’ by comparing with a defined decision threshold. Although various outstanding photonic ADC approaches have been reported, almost all of them necessitate an electrical comparator to carry out this binarization. The use of an electrical comparator is in contradiction to the aim of developing all-optical devices. In this work, we propose a new concept of an all-optical analog comparator and numerically demonstrate an implementation based on a quarter-wavelength-shifted distributed feedback laser diode (QWS DFB-LD) with multiple quantum well (MQW) structures. Our results show that the all-optical comparator is very well suited for true AO-ADCs, enabling the whole digital conversion from an analog optical signal (continuous-time signal or discrete pulse signal) to a binary representation totally in the optical domain. In particular, this all-optical analog comparator possesses a low threshold power (several mW), high extinction ratio (up to 40 dB), fast operation rate (of the order of tens of Gb/s) and a step-like transfer function.

  6. Boronic acid-tethered amphiphilic hyaluronic acid derivative-based nanoassemblies for tumor targeting and penetration.

    Science.gov (United States)

    Jeong, Jae Young; Hong, Eun-Hye; Lee, Song Yi; Lee, Jae-Young; Song, Jae-Hyoung; Ko, Seung-Hak; Shim, Jae-Seong; Choe, Sunghwa; Kim, Dae-Duk; Ko, Hyun-Jeong; Cho, Hyun-Jong

    2017-02-16

    (3-Aminomethylphenyl)boronic acid (AMPB)-installed hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs), including manassantin B (MB), were fabricated for tumor-targeted delivery. The amine group of AMPB was conjugated to the carboxylic acid group of hyaluronic acid (HA) via amide bond formation, and synthesis was confirmed by spectroscopic methods. HACE-AMPB/MB NPs with a 239-nm mean diameter, narrow size distribution, negative zeta potential, and >90% drug encapsulation efficiency were fabricated. Exposed AMPB in the outer surface of HACE-AMPB NPs (in the aqueous environment) may react with sialic acid of cancer cells. The improved cellular accumulation efficiency, in vitro antitumor efficacy, and tumor penetration efficiency of HACE-AMPB/MB NPs, compared with HACE/MB NPs, in MDA-MB-231 cells (CD44 receptor-positive human breast adenocarcinoma cells) may be based on the CD44 receptor-mediated endocytosis and phenylboronic acid-sialic acid interaction. Enhanced in vivo tumor targetability, infiltration efficiency, and antitumor efficacies of HACE-AMPB NPs, compared with HACE NPs, were observed in a MDA-MB-231 tumor-xenografted mouse model. In addition to passive tumor targeting (based on an enhanced permeability and retention effect) and active tumor targeting (interaction between HA and CD44 receptor), the phenylboronic acid-sialic acid interaction can play important roles in augmented tumor targeting and penetration of HACE-AMPB NPs. STATEMENT OF SIGNIFICANCE: (3-Aminomethylphenyl)boronic acid (AMPB)-tethered hyaluronic acid-ceramide (HACE)-based nanoparticles (NPs), including manassantin B (MB), were fabricated and their tumor targeting and penetration efficiencies were assessed in MDA-MB-231 (CD44 receptor-positive human adenocarcinoma) tumor models. MB, which exhibited antitumor efficacies via the inhibition of angiogenesis and hypoxia inducible factor (HIF)-1, was entrapped in HACE-AMPB NPs in this study. Phenylboronic acid located in the outer surface

  7. 基于数模混合的混沌映射实现∗%Chaotic map implementation based on digital-analog hybrid metho d

    Institute of Scientific and Technical Information of China (English)

    党小宇; 李洪涛; 袁泽世; 胡文

    2015-01-01

    , which confines the system performance. In this paper, a new digital-analog hybrid chaotic map with only one analog capacitor is constructed to produce random numbers. Firstly, the block diagram of digital-analog hybrid system based on the single capacitance feedback is given, and the model of the system is derived from the block diagram. Secondly, the simple logistic map is applied to the model and its nonlinear dynamics behaviors are analyzed and compared to verify the correctness and effectiveness of the proposed method. Then a more complex two-way coupled saw tooth map is used to produce pseudorandom sequences through simulation smoothly. When designing the circuits of the system, a digital-analog hybrid implementation with field programmable logic gate array and a single analog capacitor is used to realize chaotic maps, showing that it can overcome the finite word length effect of digital implementation. NIST, a general statistical test suiting for random and pseudorandom number generator cryptographic applications, is used to test the sequences produced by the new system. The results show that the new hybrid system is insensitive to the evolution of circuit parameters and the randomness of sequence is in accordance with the practical application. The circuit implementation verifies the numerical simulation and theoretical results. The high speed digital devices and a single analog capacitance are applied to the proposed random sequence generator, and therefore it can be integrated easily into the systems of digital encryption, secure communication and radar waveform generation.

  8. Analogies of Information Security

    OpenAIRE

    Sole, Amund Bauck

    2016-01-01

    In this thesis it will be tested wither analogies and metaphors would make it easier to teach the fundamental subjects of information security and hacking to people with no previous background in computer science and only basic computer skills. This will be done by conducting interview on people with no background in computer science to see what analogies work the best for different topics in information security. From the analogy getting the best response, a small game will be designed with ...

  9. Analog circuit design

    CERN Document Server

    Dobkin, Bob

    2012-01-01

    Analog circuit and system design today is more essential than ever before. With the growth of digital systems, wireless communications, complex industrial and automotive systems, designers are being challenged to develop sophisticated analog solutions. This comprehensive source book of circuit design solutions aids engineers with elegant and practical design techniques that focus on common analog challenges. The book's in-depth application examples provide insight into circuit design and application solutions that you can apply in today's demanding designs. <

  10. Analogy in CLAM

    OpenAIRE

    Melis, Erica

    1999-01-01

    CL A M is a proof planner, developed by the Dream group in Edinburgh,that mainly operates for inductive proofs. This paper addresses the questionhow an analogy model that I developed independently of CL A M can beapplied to CL A M and it presents analogy-driven proof plan construction as acontrol strategy of CL A M . This strategy is realized as a derivational analogythat includes the reformulation of proof plans. The analogical replay checkswhether the reformulated justifications of the sour...

  11. Understanding & Teaching Genetics Using Analogies

    Science.gov (United States)

    Woody, Scott; Himelblau, Ed

    2013-01-01

    We present a collection of analogies that are intended to help students better understand the foreign and often nuanced vocabulary of the genetics curriculum. Why is it called the "wild type"? What is the difference between a locus, a gene, and an allele? What is the functional (versus a rule-based) distinction between dominant and…

  12. A locked nucleic Acid-based nanocrawler

    DEFF Research Database (Denmark)

    Astakhova, I Kira; Pasternak, Karol; Campbell, Meghan A

    2013-01-01

    Herein we introduce a novel fluorescent LNA/DNA machine, a nanocrawler, which reversibly moves along a directionally polar complementary road controlled by affinity-enhancing locked nucleic acid (LNA) monomers and additional regulatory strands. Polyaromatic hydrocarbon (PAH) dyes attached to 2......'-amino-LNA monomers are incorporated at four stations of the system, enabling simple detection of the position of the nanocrawler via a step-specific color signal. The sensing is provided by highly sensitive, chemically stable, and photostable PAH LNA interstrand communication systems, including pyrene...

  13. Acid-Base Pairs in Lewis Acidic Zeolites Promote Direct Aldol Reactions by Soft Enolization.

    Science.gov (United States)

    Lewis, Jennifer D; Van de Vyver, Stijn; Román-Leshkov, Yuriy

    2015-08-17

    Hf-, Sn-, and Zr-Beta zeolites catalyze the cross-aldol condensation of aromatic aldehydes with acetone under mild reaction conditions with near quantitative yields. NMR studies with isotopically labeled molecules confirm that acid-base pairs in the Si-O-M framework ensemble promote soft enolization through α-proton abstraction. The Lewis acidic zeolites maintain activity in the presence of water and, unlike traditional base catalysts, in acidic solutions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Renal acidification responses to respiratory acid-base disorders.

    Science.gov (United States)

    Madias, Nicolaos E

    2010-01-01

    Respiratory acid-base disorders are those abnormalities in acid-base equilibrium that are expressed as primary changes in the arterial carbon dioxide tension (PaCO2). An increase in PaCO2 (hypercapnia) acidifies body fluids and initiates the acid-base disturbance known as respiratory acidosis. By contrast, a decrease in PaCO2 (hypocapnia) alkalinizes body fluids and initiates the acid-base disturbance known as respiratory alkalosis. The impact on systemic acidity of these primary changes in PaCO2 is ameliorated by secondary, directional changes in plasma [HCO3¯] that occur in 2 stages. Acutely, hypercapnia or hypocapnia yields relatively small changes in plasma [HCO3¯] that originate virtually exclusively from titration of the body's nonbicarbonate buffers. During sustained hypercapnia or hypocapnia, much larger changes in plasma [HCO3¯] occur that reflect adjustments in renal acidification mechanisms. Consequently, the deviation of systemic acidity from normal is smaller in the chronic forms of these disorders. Here we provide an overview of the renal acidification responses to respiratory acid-base disorders. We also identify gaps in knowledge that require further research.

  15. Priming analogical reasoning with false memories.

    Science.gov (United States)

    Howe, Mark L; Garner, Sarah R; Threadgold, Emma; Ball, Linden J

    2015-08-01

    Like true memories, false memories are capable of priming answers to insight-based problems. Recent research has attempted to extend this paradigm to more advanced problem-solving tasks, including those involving verbal analogical reasoning. However, these experiments are constrained inasmuch as problem solutions could be generated via spreading activation mechanisms (much like false memories themselves) rather than using complex reasoning processes. In three experiments we examined false memory priming of complex analogical reasoning tasks in the absence of simple semantic associations. In Experiment 1, we demonstrated the robustness of false memory priming in analogical reasoning when backward associative strength among the problem terms was eliminated. In Experiments 2a and 2b, we extended these findings by demonstrating priming on newly created homonym analogies that can only be solved by inhibiting semantic associations within the analogy. Overall, the findings of the present experiments provide evidence that the efficacy of false memory priming extends to complex analogical reasoning problems.

  16. Efficiency and hardware comparison of analog control-based and digital control-based 70 W two-stage power factor corrector and DC-DC converters

    DEFF Research Database (Denmark)

    Török, Lajos; Munk-Nielsen, Stig

    2011-01-01

    A comparison of an analog and a digital controller driven 70 W two-stage power factor corrector converter is presented. Both controllers are operated in average current-mode-control for the PFC and peak current control for the DC-DC converter. Digital controller design and converter modeling is d...... is described. Results show that digital control can compete with the analog one in efficiency, PFC and THD.......A comparison of an analog and a digital controller driven 70 W two-stage power factor corrector converter is presented. Both controllers are operated in average current-mode-control for the PFC and peak current control for the DC-DC converter. Digital controller design and converter modeling...

  17. Switched-Current Technology Based Reconfigurable Analog Circuit for Multi-Function Analog Signal Processing%面向多功能模拟信号处理的开关电流型可重构模拟电路研究

    Institute of Scientific and Technical Information of China (English)

    王友仁; 祝鸣涛; 任晋华; 崔江; 林华

    2011-01-01

    现有的离散时间型可重构模拟电路采用开关电容技术,存在功能有限、带宽低、与数字CMOS工艺不兼容等问题.本文提出了一种基于电流模取样数据技术的可重构模拟电路,能够与数字CMOS工艺技术兼容.设计了细粒度开关电流型可重构模拟单元,设计了面向开关电流型CAB互连的可编程网络结构.在4×2规模的可重构模拟阵列上,重构实现了三个典型模拟电路应用实例,实验结果证明了所设计开关电流型可重构模拟电路是有效的,能重构实现多种功能的模拟电路.%Conventional discrete time mode reconfigurable analog circuits are designed with the switched capacitor teclnology,which have the disadvantage of function limitation,tower band pass,ani being not compatible with digital CMOS process technology in hybrid integrated circuits. This paper presented a Reconfigurable Analog Circuit (RAC) based on Current Mode Sampled Data Technology (CMSDT), which was fully compatible with the digital CMOS process. The Configurable Analog Block (CAB) based on switched current technology was developed,and the progrannable intercnnect network structure for the switched currenyCAB was proposed. Three analog circuits for application examples have been achieved respectively by reconfiguration in the 4 × 2 recongurable analog array. The simulation experimental results show that the designed reconfigurable analog circuit is effective and can realize multi-function analog circuit with reconfiguration.

  18. An Olfactory Indicator for Acid-Base Titrations.

    Science.gov (United States)

    Flair, Mark N.; Setzer, William N.

    1990-01-01

    The use of an olfactory acid-base indicator in titrations for visually impaired students is discussed. Potential olfactory indicators include eugenol, thymol, vanillin, and thiophenol. Titrations performed with each indicator with eugenol proved to be successful. (KR)

  19. Acid-base and potassium disorders in liver disease.

    Science.gov (United States)

    Ahya, Shubhada N; José Soler, Maria; Levitsky, Josh; Batlle, Daniel

    2006-11-01

    Acid-base and potassium disorders occur frequently in the setting of liver disease. As the liver's metabolic function worsens, particularly in the setting of renal dysfunction, hemodynamic compromise, and hepatic encephalopathy, acid-base disorders ensue. The most common acid-base disorder is respiratory alkalosis. Metabolic acidosis alone or in combination with respiratory alkalosis also is common. Acid-base disorders in patients with liver disease are complex. The urine anion gap may help to distinguish between chronic respiratory alkalosis and hyperchloremic metabolic acidosis when a blood gas is not available. A negative urine anion gap helps to rule out chronic respiratory alkalosis. In this disorder a positive urine anion gap is expected owing to suppressed urinary acidification. Distal renal tubular acidosis occurs in autoimmune liver disease such as primary biliary cirrhosis, but often is a functional defect from impaired distal sodium delivery. Potassium disorders are often the result of the therapies used to treat advanced liver disease.

  20. Synthesis and catalytic application of amino acid based dendritic macromolecules

    NARCIS (Netherlands)

    Koten, G. van; Gossage, R.A.; Jastrzebski, J.T.B.H.; Ameijde, J. van; Mulders, S.J.E.; Brouwer, Arwin J.; Liskamp, R.M.J.

    1999-01-01

    The use of amino acid based dendrimers as molecular scaffolds for the attachment of catalytically active organometallic Ni ''pincer'' complexes, via a urea functionality, is described; the dendrimer catalysts have comparable activity to their mononuclear (NCN)NiX analogues.

  1. Acid-base strengths in m-cresol

    NARCIS (Netherlands)

    Bos, M.; Dahmen, E.A.M.F.

    1971-01-01

    For various acids and bases dissociation constants were determined conductimetrically in m-cresol. A glass electrode was calibrated by means of some compounds with dissociation constants known from conductivity measurements. Potentiometric titrations with this calibrated glass electrode gave dissoci

  2. Towards lactic acid bacteria-based biorefineries.

    Science.gov (United States)

    Mazzoli, Roberto; Bosco, Francesca; Mizrahi, Itzhak; Bayer, Edward A; Pessione, Enrica

    2014-11-15

    Lactic acid bacteria (LAB) have long been used in industrial applications mainly as starters for food fermentation or as biocontrol agents or as probiotics. However, LAB possess several characteristics that render them among the most promising candidates for use in future biorefineries in converting plant-derived biomass-either from dedicated crops or from municipal/industrial solid wastes-into biofuels and high value-added products. Lactic acid, their main fermentation product, is an attractive building block extensively used by the chemical industry, owing to the potential for production of polylactides as biodegradable and biocompatible plastic alternative to polymers derived from petrochemicals. LA is but one of many high-value compounds which can be produced by LAB fermentation, which also include biofuels such as ethanol and butanol, biodegradable plastic polymers, exopolysaccharides, antimicrobial agents, health-promoting substances and nutraceuticals. Furthermore, several LAB strains have ascertained probiotic properties, and their biomass can be considered a high-value product. The present contribution aims to provide an extensive overview of the main industrial applications of LAB and future perspectives concerning their utilization in biorefineries. Strategies will be described in detail for developing LAB strains with broader substrate metabolic capacity for fermentation of cheaper biomass.

  3. Demonstration of an online tool to assist managed care formulary evidence-based decision making: meta-analysis of topical prostaglandin analog efficacy

    Directory of Open Access Journals (Sweden)

    Kymes SM

    2011-07-01

    Full Text Available Steven M Kymes1, Caroline Burk2, Todd Feinman3, Julia M Williams4, David A Hollander41Department of Ophthalmology and Visual Sciences, Washington University School of Medicine, St Louis, MO, USA; 2Health Outcomes, Allergan Inc, Irvine, CA, USA; 3Doctor Evidence LLC, Santa Monica, CA, USA; 4Global Medical Affairs, Allergan Inc, Irvine, CA, USABackground: The purpose of this paper was to demonstrate the use of an online service for conducting a systematic review and meta-analysis of the efficacy of topical prostaglandin analogs in reducing intraocular pressure (IOP in glaucoma and ocular hypertension.Methods: An online service provider (Doctor Evidence reviewed and extracted data from the peer-reviewed literature through September 2009. Randomized controlled studies of at least three months' duration assessing at least two prostaglandin analogs in patients with primary open-angle glaucoma, ocular hypertension, or normal-tension glaucoma were included. The primary endpoint was mean IOP. Summary estimates were created using random-effects models. The Q Chi-square test was used to assess statistical heterogeneity.Results: Sixteen studies satisfied the inclusion criteria and were analyzed. On average, greater IOP-lowering was seen with bimatoprost relative to latanoprost (1 mmHg, P = 0.025 and travoprost (0.8 mmHg, P = 0.033 based on mean IOP after 12–26 weeks of treatment. No statistical difference was observed in IOP-lowering between latanoprost and travoprost (P = 0.841. Findings were similar to previously published meta-analyses of topical prostaglandin analogs.Conclusion: Systematic reviews relying on meta-analytic techniques to create summary statistics are considered to be the "gold standard" for synthesizing evidence to support clinical decision-making. However, the process is time-consuming, labor-intensive, and outside the capability of most formulary managers. We have demonstrated the effectiveness of a commercial service that facilitates

  4. Synthesis and antimicrobial activities of new higher amino acid Schiff base derivatives of 6-aminopenicillanic acid and 7-aminocephalosporanic acid

    Science.gov (United States)

    Özdemir (nee Güngör), Özlem; Gürkan, Perihan; Özçelik, Berrin; Oyardı, Özlem

    2016-02-01

    Novel β-lactam derivatives (1c-3c) (1d-3d) were produced by using 6-aminopenicillanic acid (6-APA), 7-aminocephalosporanic acid (7-ACA) and the higher amino acid Schiff bases. The synthesized compounds were characterized by elemental analysis, IR, 1H/13C NMR and UV-vis spectra. Antibacterial activities of all the higher amino acid Schiff bases (1a-3a) (1b-3b) and β-lactam derivatives were screened against three gram negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Acinetobacter baumannii RSKK 02026), three gram positive bacteria (Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 07005, Bacillus subtilis ATCC 6633) and their drug-resistant isolates by using broth microdilution method. Two fungi (Candida albicans and Candida krusei) were used for antifungal activity.

  5. Acid-base homeostasis in the human system

    Science.gov (United States)

    White, R. J.

    1974-01-01

    Acid-base regulation is a cooperative phenomena in vivo with body fluids, extracellular and intracellular buffers, lungs, and kidneys all playing important roles. The present account is much too brief to be considered a review of present knowledge of these regulatory systems, and should be viewed, instead, as a guide to the elements necessary to construct a simple model of the mutual interactions of the acid-base regulatory systems of the body.

  6. Kislinsko-bazno ravnovesje: Acid-base balance:

    OpenAIRE

    2002-01-01

    Acids are donors, while bases are acceptors of protons in solutions. Many various acids and bases are incorporated into organisms by everyday alimentation and cell metabolism, while the output routes are the respiratory system, kidneys and gastrointestinal system. The concentration of free protonsin the blood (expressed as pH value) is strictly regulated, as it has agreat impact on cell metabolism. There are many ways in which organisms defend themselves against harmful pH changes. The first ...

  7. A low-power inverter-based CMOS level-crossing analog-to-digital converter for low-frequency biosignal sensing

    Science.gov (United States)

    Tanaka, Suiki; Niitsu, Kiichi; Nakazato, Kazuo

    2016-03-01

    Low-power analog-to-digital conversion is a key technique for power-limited biomedical applications such as power-limited continuous glucose monitoring. However, a conventional uniform-sampling analog-to-digital converter (ADC) is not suitable for nonuniform biosignals. A level-crossing ADC (LC-ADC) is a promising candidate for low-power biosignal processing because of its event-driven properties. The LC-ADC acquires data by level-crossing sampling. When an input signal crosses the threshold level, the LC-ADC samples the signal. The conventional LC-ADC employs a power-hungry comparator. In this paper, we present a low-power inverter-based LC-ADC. By adjusting the threshold level of the inverter, it can be used as a threshold-fixed window comparator. By using the inverter as an alternative to a comparator, power consumption can be markedly reduced. As a result, the total power consumption is successfully reduced by 90% of that of previous LC-ADC. The inverter-based LC-ADC was found to be very suitable for use in power-limited biomedical devices.

  8. A Power Conditioning Stage Based on Analog-Circuit MPPT Control and a Superbuck Converter for Thermoelectric Generators in Spacecraft Power Systems

    Science.gov (United States)

    Sun, Kai; Wu, Hongfei; Cai, Yan; Xing, Yan

    2014-06-01

    A thermoelectric generator (TEG) is a very important kind of power supply for spacecraft, especially for deep-space missions, due to its long lifetime and high reliability. To develop a practical TEG power supply for spacecraft, a power conditioning stage is indispensable, being employed to convert the varying output voltage of the TEG modules to a definite voltage for feeding batteries or loads. To enhance the system reliability, a power conditioning stage based on analog-circuit maximum-power-point tracking (MPPT) control and a superbuck converter is proposed in this paper. The input of this power conditioning stage is connected to the output of the TEG modules, and the output of this stage is connected to the battery and loads. The superbuck converter is employed as the main circuit, featuring low input current ripples and high conversion efficiency. Since for spacecraft power systems reliable operation is the key target for control circuits, a reset-set flip-flop-based analog circuit is used as the basic control circuit to implement MPPT, being much simpler than digital control circuits and offering higher reliability. Experiments have verified the feasibility and effectiveness of the proposed power conditioning stage. The results show the advantages of the proposed stage, such as maximum utilization of TEG power, small input ripples, and good stability.

  9. The Bipolar Field-Effect Transistor:Ⅶ. The Unipolar Current Mode for Analog-RF Operation(Two-MOS-Gates on Pure-Base

    Institute of Scientific and Technical Information of China (English)

    Jie Binbin; Sah Chih-Tang

    2009-01-01

    This paper reports the DC steady-state current-voltage and conductance-voltage characteristics of a Bipolar Field-Effect Transistor (BiFET) under the unipolar (electron) current mode of operation, with bipolar (elec-tron and hole) charge distributions considered. The model BiFET example presented has two MOS-gates on the two surfaces of a thin pure silicon base layer with electron and hole contacts on both edges of the thin base. The hole contacts on both edges of the thin pure base layer are grounded to give zero hole current. This 1-transistor analog-RF Basic Building Block nMOS amplifier circuit, operated in the unipolar current mode, complements the 1-transistor digital Basic Build Block CMOS voltage inverter circuit, operated in the bipolar-current mode just presented by us.

  10. A mechanism-based 3D-QSAR approach for classification and prediction of acetylcholinesterase inhibitory potency of organophosphate and carbamate analogs

    Science.gov (United States)

    Lee, Sehan; Barron, Mace G.

    2016-04-01

    Organophosphate (OP) and carbamate esters can inhibit acetylcholinesterase (AChE) by binding covalently to a serine residue in the enzyme active site, and their inhibitory potency depends largely on affinity for the enzyme and the reactivity of the ester. Despite this understanding, there has been no mechanism-based in silico approach for classification and prediction of the inhibitory potency of ether OPs or carbamates. This prompted us to develop a three dimensional prediction framework for OPs, carbamates, and their analogs. Inhibitory structures of a compound that can form the covalent bond were identified through analysis of docked conformations of the compound and its metabolites. Inhibitory potencies of the selected structures were then predicted using a previously developed three dimensional quantitative structure-active relationship. This approach was validated with a large number of structurally diverse OP and carbamate compounds encompassing widely used insecticides and structural analogs including OP flame retardants and thio- and dithiocarbamate pesticides. The modeling revealed that: (1) in addition to classical OP metabolic activation, the toxicity of carbamate compounds can be dependent on biotransformation, (2) OP and carbamate analogs such as OP flame retardants and thiocarbamate herbicides can act as AChEI, (3) hydrogen bonds at the oxyanion hole is critical for AChE inhibition through the covalent bond, and (4) π-π interaction with Trp86 is necessary for strong inhibition of AChE. Our combined computation approach provided detailed understanding of the mechanism of action of OP and carbamate compounds and may be useful for screening a diversity of chemical structures for AChE inhibitory potency.

  11. Analog circuit diagnosis with fault dictionary method based on DAGSVC*%基于DAGSVC的模拟电路故障字典法

    Institute of Scientific and Technical Information of China (English)

    姜媛媛; 韩振云; 崔江

    2011-01-01

    Focusing on the design of problem of fault diagnosis of analog circuit and classifier with support vector machines(SVMs) ,a new method of fault dictionary based on directed acyclic graph SVMs classifier (DAGSVC) is presented, and a specification for estimating the average test complexity of the support vector machine classifier (SVC) is also compared. Two actual analog filter are tested to validate the proposed method,whose performance is proven to be superior to the traditional methods, such as “1-v-r” SVC and “l-v-1” SVC. The proposed method, being proper to perform analog circuit diagnosis and faults isolation,could also achieve almost the same diagnosis rate as the clustering binary tree SVC,whose test structure is not unique.%针对模拟电路的故障诊断和支持向量机分类器的设计问题,讨论了一种基于有向无环图支持向量机分类器(DAGSVC)的故障字典新方法,并比较了几种支持向量机故障分类器的平均测试复杂度指标.通过对2个实际模拟滤波器的实际测试和验证表明:该方法性能要优于"1-v-r"SVC,"1-v-1"SVC等常规的故障分类器,并和聚类二叉树SVC的诊断性能接近,适合模拟电路的故障分类和诊断.

  12. A novel protein characterization based on Pseudo Amino Acids composition and Star-like graph topological indices.

    Science.gov (United States)

    He, Pingan; Tao, Hong; Ma, Tingting; Dai, Qi; Yao, Yuhua

    2017-02-17

    In the work, a new description of proteins based on five topological indices of star-like graph representation and the occurrence frequency of 20 amino acids was proposed to compare the similarities of proteins. A phylogenetic tree of eight ND6 proteins was constructed to demonstrate the effectiveness and rationality of our approach. Analogously, we applied this method to RNA polymerase proteins of some subtypes of influenza virus to infer their phylogenetic relationship. The results showed that the phylogenetic relationship among RNA polymerase of influenza virus is closely related to distributions of species virus host and geographical distribution.

  13. Speed limits for acid-base chemistry in aqueous solutions.

    Science.gov (United States)

    Donten, Mateusz L; Vandevondele, Joost; Hamm, Peter

    2012-01-01

    Proton transfer reactions, including acid-base recombination, are commonly considered to occur 'nearly instantaneously'. However, their actual time scales may stretch far into the microsecond range, as acid-base reactions are diffusion controlled and the concentrations are low near neutral pH. The interplay of competing bases in the pH relaxation is illustrated using a model acid-base system consisting of o-nitrobenzaldehyde (oNBA) as a proton cage and acetate ions and hydroxyl ions as bases. The kinetically controlled behavior leads to highly counterintuitive states, i.e. acetate ions are transiently protonated for hundreds of nanoseconds despite the presence of a much stronger base OH-.

  14. Mineral formation on metallic copper in a `Future repository site environment`: Textural considerations based on natural analogs

    Energy Technology Data Exchange (ETDEWEB)

    Amcoff, Oe. [Uppsala Univ. (Sweden). Inst. of Earth Sciences

    1998-01-01

    Copper mineral formation in the Swedish `repository site environment` is discussed. Special attention is given to ore mineral textures (=the spatial relation among minerals), with examples given from nature. It is concluded: By analogy with observations from natural occurrences, an initial coating of Cu-oxide on the canister surface (because of entrapped air during construction) will probably not hinder a later sulphidation process. Early formation of Cu-sulphides on the canister surface may be accompanied by formation of CuFe-sulphides. The latter phase(s) may form through replacement of the Cu-sulphides or, alternatively, by means of reaction between dissolved copper and fine-grained iron sulphide (pyrite) in the surrounding bentonite. Should for some reason the bentonite barrier fail and the conditions become strongly oxidizing, we can expect crustifications and rhythmic growths of Cu(II)-phases, like malachite (Cu{sub 2}(OH){sub 2}CO{sub 3}). A presence of Fe{sup 2} in the clay minerals making up the bentonite might prove to have an adverse effect on the canister stability, since, in this case, the bentonite might be expected to act as a sink for dissolved copper. The mode of mineral growth along the copper - bentonite interface remains an open question.

  15. Response Generation Norms for Verbal Analogies.

    Science.gov (United States)

    Ingram, Albert; Pellegrino, James W.

    Normative data were collected for the generation of responses to 150 incomplete verbal analogies. Two types of normative data are provided: (a) the probabilities associated with each response produced for each analogy base and (b) the probabilities that initial responses represented the appropriate semantic relationship, with a division of…

  16. Hydraulic Capacitor Analogy

    Science.gov (United States)

    Baser, Mustafa

    2007-01-01

    Students have difficulties in physics because of the abstract nature of concepts and principles. One of the effective methods for overcoming students' difficulties is the use of analogies to visualize abstract concepts to promote conceptual understanding. According to Iding, analogies are consistent with the tenets of constructivist learning…

  17. Challenges in Using Analogies

    Science.gov (United States)

    Lin, Shih-Yin; Singh, Chandralekha

    2011-01-01

    Learning physics requires understanding the applicability of fundamental principles in a variety of contexts that share deep features. One way to help students learn physics is via analogical reasoning. Students can be taught to make an analogy between situations that are more familiar or easier to understand and another situation where the same…

  18. Discovery of high potency, single-chain insulin analogs with a shortened B-chain and nonpeptide linker.

    Science.gov (United States)

    Kaur, Zachary P; Ochman, Alexander R; Mayer, John P; Gelfanov, Vasily M; DiMarchi, Richard D

    2013-08-16

    A series of novel, single chain insulin analogs containing polyethylene glycol based connecting segments were synthesized by native chemical ligation and tested for biological activity. While the full length single chain insulin analogs exhibited low potency, deletion of amino acids B26-B30 unexpectedly generated markedly higher activity. This observation is unprecedented in all previous studies of single chain insulin analogs and is consistent with the presumption that in the native hormone this sequence must translocate to achieve high potency insulin receptor interaction. Optimization of the sequence yielded an insulin analog with potency and selectivity comparable to that of native insulin. These results establish a basis for discovery of novel higher potency, single chain insulin analogs of shortened length.

  19. Synaptic dynamics in analog VLSI.

    Science.gov (United States)

    Bartolozzi, Chiara; Indiveri, Giacomo

    2007-10-01

    Synapses are crucial elements for computation and information transfer in both real and artificial neural systems. Recent experimental findings and theoretical models of pulse-based neural networks suggest that synaptic dynamics can play a crucial role for learning neural codes and encoding spatiotemporal spike patterns. Within the context of hardware implementations of pulse-based neural networks, several analog VLSI circuits modeling synaptic functionality have been proposed. We present an overview of previously proposed circuits and describe a novel analog VLSI synaptic circuit suitable for integration in large VLSI spike-based neural systems. The circuit proposed is based on a computational model that fits the real postsynaptic currents with exponentials. We present experimental data showing how the circuit exhibits realistic dynamics and show how it can be connected to additional modules for implementing a wide range of synaptic properties.

  20. Estimation of channel mismatches in time-interleaved analog-to-digital converters based on fractional delay and sine curve fitting.

    Science.gov (United States)

    Guo, Lianping; Tian, Shulin; Jiang, Jun

    2015-03-01

    This paper proposes an algorithm to estimate the channel mismatches in time-interleaved analog-to-digital converter (TIADC) based on fractional delay (FD) and sine curve fitting. Choose one channel as the reference channel and apply FD to the output samples of reference channel to obtain the ideal samples of non-reference channels with no mismatches. Based on least square method, the sine curves are adopted to fit the ideal and the actual samples of non-reference channels, and then the mismatch parameters can be estimated by comparing the ideal sine curves and the actual ones. The principle of this algorithm is simple and easily understood. Moreover, its implementation needs no extra circuits, lowering the hardware cost. Simulation results show that the estimation accuracy of this algorithm can be controlled within 2%. Finally, the practicability of this algorithm is verified by the measurement results of channel mismatch errors of a two-channel TIADC prototype.

  1. Structure-based virtual screening, molecular docking, ADMET and molecular simulations to develop benzoxaborole analogs as potential inhibitor against Leishmania donovani trypanothione reductase.

    Science.gov (United States)

    Pandey, Rajan Kumar; Kumbhar, Bajarang Vasant; Sundar, Shyam; Kunwar, Ambarish; Prajapati, Vijay Kumar

    2017-02-01

    Visceral leishmaniasis (VL) is the most fatal form of leishmaniasis and it affects 70 countries worldwide. Increasing drug resistant for antileishmanial drugs such as miltefosine, sodium stibogluconate and pentamidine has been reported in the VL endemic region. Amphotericin B has shown potential antileishmanial activity in different formulations but its cost of treatment and associated nephrotoxicity have limited its use by affected people living in the endemic zone. To control the VL infection in the affected countries, it is necessary to develop new antileishmanial compounds with high efficacy and negligible toxicity. Computer aided programs such as binding free energy estimation; ADMET prediction and molecular dynamics simulation can be used to investigate novel antileishmanial molecules in shorter duration. To develop antileishmanial lead molecule, we performed standard precision (SP) docking for 1160 benzoxaborole analogs along with reference inhibitors against trypanothione reductase of Leishmania parasite. Furthermore, extra precision (XP) docking, ADMET prediction, prime MM-GBSA was conducted over 115 ligands, showing better docking score than reference inhibitors to get potential antileishmanial compounds. Simultaneously, area under the curve (AUC) was estimated using ROC plot to validate the SP and XP docking protocol. Later on, two benzoxaborole analogs with best MM-GBSA ΔG-bind were subjected to molecular simulation and docking confirmation to ensure the ligand interaction with TR. The presented drug discovery based on computational study confirms that BOB27 can be used as a potential drug candidate and warrants further experimental investigation to fight against VL in endemic areas.

  2. Broadband receiver-based distortion elimination in phase-modulated analog optical links using four-wave mixing

    Science.gov (United States)

    Bhatia, Amit; Ting, Hong-Fu; Foster, Mark A.

    2015-03-01

    We present a method for full distortion elimination in phase-modulated analog optical links using the nonlinear optical process of four-wave mixing (FWM). Phase-modulated links consist of a laser and phase modulator in the transmitter and an interferometer (or local oscillator) and photodiode in the receiver. Phase modulation is a linear process, so distortion is introduced in the interferometric detection process. Quadrature biasing eliminates even-order distortion products, leaving only odd-order distortion. Here we introduce a method for eliminating these odd-order distortion products in the receiver. A small portion of the phase-modulated signal is tapped and combined with an unmodulated CW laser to seed a cascaded FWM comb source. This process generates an array of lightwaves with integer multiples of the signal's phase modulation. By suitably scaling and combining these lightwaves with the original signal the overall transfer function of the interferometric receiver can be linearized (or given another tailored shape) through a Fourier synthesis approach. By combining a single lightwave from the generated comb with the original signal, we demonstrate the complete elimination of third-order distortion from the phase-modulated link leaving fifth-order distortion as the dominate source of distortion. We show a 17.6-dB SFDR improvement (1-Hz bandwidth) for a 6 GHz link operating at 5-mA total photocurrent and a 16.4-dB SFDR improvement (1-Hz bandwidth) for a 15 GHz link operating at 10-mA total photocurrent. By appropriately combining additional lightwaves from the generated comb, higher-order distortion products can be eliminated to produce an ideal linear (or custom shaped) transfer function.

  3. Direct enantioseparation of underivatized aliphatic 3-hydroxyalkanoic acids with a quinine-based zwitterionic chiral stationary phase.

    Science.gov (United States)

    Ianni, Federica; Pataj, Zoltán; Gross, Harald; Sardella, Roccaldo; Natalini, Benedetto; Lindner, Wolfgang; Lämmerhofer, Michael

    2014-10-10

    While aliphatic 2-hydroxyalkanoic acids have been more or less successfully enantioseparated with various chiral stationary phases by HPLC and GC, analogous applications on underivatized aliphatic 3-hydroxyalkanoic acids are completely absent in the scientific literature. With the aim of closing this gap, the enantioseparation of 3-hydroxybutyric acid, 3-hydroxydecanoic acid and 3-hydroxymyristic acid has been performed with two ion-exchange type chiral stationary phases (CSPs): one containing the anion-exchange type tert-butyl carbamoyl quinine chiral selector motif (Chiralpak QN-AX), and the other carrying the new zwitterionic variant based on trans-(S,S)-2-aminocyclohexanesulfonic acid-derivatized quinine carbamate (Chiralpak ZWIX(+)) as the chiral selector and enantiodiscriminating element, respectively. The zwitterionic enantiorecognition material provided better results in terms of enantioselectivity and resolution compared to the anion-exchanger CSP at reduced retention times due to the intramolecular counterion effect imposed by the sulfonic acid moiety and its competition with the 3-hydroxyalkanoic acid analyte for ionic interaction at the quininium-anion exchanger site. It is thus recommended as the CSP of first choice for enantioseparations of the class of aliphatic 3-hydroxyalkanoic acids. With use of polar organic eluent composed of ACN/MeOH/AcOH - 95/5/0.05 (v/v/v), a good compromise in terms of analysis time and enantioresolution quality was accomplished. The major experimental variables have been investigated for optimization of the resolution and allowed to derive information on the enantiorecognition mechanism. Corresponding Chiralpak ZWIX(-), based on pseudo-enantiomeric selector derived from quinidine and trans-(R,R)-2-aminocyclohexanesulfonic acid with opposite configurations provided reversed enantiomer elution orders. It has further to be stressed that these separations can be obtained with mass spectrometry compatible mobile phases.

  4. Assessment of acid-base balance. Stewart's approach.

    Science.gov (United States)

    Fores-Novales, B; Diez-Fores, P; Aguilera-Celorrio, L J

    2016-04-01

    The study of acid-base equilibrium, its regulation and its interpretation have been a source of debate since the beginning of 20th century. Most accepted and commonly used analyses are based on pH, a notion first introduced by Sorensen in 1909, and on the Henderson-Hasselbalch equation (1916). Since then new concepts have been development in order to complete and make easier the understanding of acid-base disorders. In the early 1980's Peter Stewart brought the traditional interpretation of acid-base disturbances into question and proposed a new method. This innovative approach seems more suitable for studying acid-base abnormalities in critically ill patients. The aim of this paper is to update acid-base concepts, methods, limitations and applications. Copyright © 2015 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.

  5. Role of acids and bases in nanoparticle growth

    Science.gov (United States)

    Yli-Juuti, Taina; Barsanti, Kelley; Bzdek, Bryan; Hildebrandt Ruiz, Lea; Jokinen, Tuija; Kieloaho, Antti-Jussi; Makkonen, Ulla; Petäjä, Tuukka; Ruuskanen, Taina; Johnston, Murray; Kulmala, Markku; Riipinen, Ilona

    2014-05-01

    Secondary aerosol particles that are formed in atmosphere by gas-to-particle conversion during new particle formation events have potential to affect climate significantly due to their typically high number concentrations. This, however, requires that the freshly formed nanoparticles of about 1 nm in diameter grow tens of nanometers and reach climatically relevant sizes, i.e. sizes where they can act as cloud condensation nuclei. During the growth towards larger sizes the nanoparticles are subject to coagulational losses, and the rate at which the nanoparticles grow by condensation of vapors is a key factor affecting their probability to survive to climatically relevant sizes. Vapors that condense on the nanoparticles can be produced in the atmosphere from volatile compounds through gas phase chemical reactions, and their volatility can also be further lowered by particle phase processes. Therefore, particle composition and particle phase processes may influence nanoparticle growth. We study the growth of atmospheric nanoparticles and especially the role of particle phase salt formation in the nanoparticle growth using MABNAG model (Model for Acid-Base chemistry in NAnoparticle Growth) and by comparing to atmospheric measurements. MABNAG is a condensation growth model for aqueous solution particles. In MABNAG the dynamics of gas phase mass transport of vapors to particle are coupled with thermodynamics of particle phase acid-base chemistry, and both the composition and size dependence of equilibrium vapor pressures are accounted for. The model is applied especially for boreal forest environment. Here nanoparticle growth is modeled with a system of water, two acids (sulfuric acid and an organic acid) and two bases (ammonia and an amine) as condensing vapors. Focus is on the neutralization of acids by the bases and the related effects on the particle growth. According to the model predictions the enhancement of condensation of organic acid due to salt formation is

  6. Computational approaches to analogical reasoning current trends

    CERN Document Server

    Richard, Gilles

    2014-01-01

    Analogical reasoning is known as a powerful mode for drawing plausible conclusions and solving problems. It has been the topic of a huge number of works by philosophers, anthropologists, linguists, psychologists, and computer scientists. As such, it has been early studied in artificial intelligence, with a particular renewal of interest in the last decade. The present volume provides a structured view of current research trends on computational approaches to analogical reasoning. It starts with an overview of the field, with an extensive bibliography. The 14 collected contributions cover a large scope of issues. First, the use of analogical proportions and analogies is explained and discussed in various natural language processing problems, as well as in automated deduction. Then, different formal frameworks for handling analogies are presented, dealing with case-based reasoning, heuristic-driven theory projection, commonsense reasoning about incomplete rule bases, logical proportions induced by similarity an...

  7. Poly (ricinoleic acid) based novel thermosetting elastomer.

    Science.gov (United States)

    Ebata, Hiroki; Yasuda, Mayumi; Toshima, Kazunobu; Matsumura, Shuichi

    2008-01-01

    A novel bio-based thermosetting elastomer was prepared by the lipase-catalyzed polymerization of methyl ricinoleate with subsequent vulcanization. Some mechanical properties of the cured carbon black-filled polyricinoleate compounds were evaluated as a thermosetting elastomer. It was found that the carbon black-filled polyricinoleate compounds were readily cured by sulfur curatives to produce a thermosetting elastomer that formed a rubber-like sheet with a smooth and non-sticky surface. The curing behaviors and mechanical properties were dependent on both the molecular weight of the polyricinoleate and the amount of the sulfur curatives. Cured compounds consisting of polyricinoleate with a molecular weight of 100,800 showed good mechanical properties, such as a hardness of 48 A based on the durometer A measurements, a tensile strength at break of 6.91 MPa and an elongation at break of 350%.

  8. Acid-base disturbance in patients with cirrhosis

    DEFF Research Database (Denmark)

    Henriksen, Jens H; Bendtsen, Flemming; Møller, Søren

    2015-01-01

    PURPOSE: Acid-base disturbances were investigated in patients with cirrhosis in relation to hemodynamic derangement to analyze the hyperventilatory effects and the metabolic compensation. METHODS: A total of 66 patients with cirrhosis and 44 controls were investigated during a hemodynamic study......, and effects of unidentified ions (all Pacid-base disturbances could not be identified. CONCLUSION: Hypocapnic alkalosis is related to disease severity and hyperdynamic systemic circulation in patients with cirrhosis. The metabolic compensation includes...... alterations in serum albumin and water retention that may result in a delicate acid-base balance in these patients....

  9. Nanopore-based sequencing and detection of nucleic acids.

    Science.gov (United States)

    Ying, Yi-Lun; Zhang, Junji; Gao, Rui; Long, Yi-Tao

    2013-12-09

    Nanopore-based techniques, which mimic the functions of natural ion channels, have attracted increasing attention as unique methods for single-molecule detection. The technology allows the real-time, selective, high-throughput analysis of nucleic acids through both biological and solid-state nanopores. In this Minireview, the background and latest progress in nanopore-based sequencing and detection of nucleic acids are summarized, and light is shed on a novel platform for nanopore-based detection. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Developmental Patterns in the Solution of Verbal Analogies.

    Science.gov (United States)

    Sternberg, Robert J.; Nigro, Georgia

    1980-01-01

    Examines developmental patterns in the solution of verbal analogies. Twenty subjects in each of grades 3, 6, 9, and in college were tested on their relative abilities to solve 180 verbal analogies based on five different verbal relations. (CM)

  11. Parallel proton transfer pathways in aqueous acid-base reactions

    NARCIS (Netherlands)

    Cox, M.J.; Bakker, H.J.

    2008-01-01

    We study the mechanism of proton transfer (PT) between the photoacid 8-hydroxy-1,3, 6-pyrenetrisulfonic acid (HPTS) and the base chloroacetate in aqueous solution. We investigate both proton and deuteron transfer reactions in solutions with base concentrations ranging from 0.25M to 4M. Using femtose

  12. Soil Studies: Applying Acid-Base Chemistry to Environmental Analysis.

    Science.gov (United States)

    West, Donna M.; Sterling, Donna R.

    2001-01-01

    Laboratory activities for chemistry students focus attention on the use of acid-base chemistry to examine environmental conditions. After using standard laboratory procedures to analyze soil and rainwater samples, students use web-based resources to interpret their findings. Uses CBL probes and graphing calculators to gather and analyze data and…

  13. Soil Studies: Applying Acid-Base Chemistry to Environmental Analysis.

    Science.gov (United States)

    West, Donna M.; Sterling, Donna R.

    2001-01-01

    Laboratory activities for chemistry students focus attention on the use of acid-base chemistry to examine environmental conditions. After using standard laboratory procedures to analyze soil and rainwater samples, students use web-based resources to interpret their findings. Uses CBL probes and graphing calculators to gather and analyze data and…

  14. The coulometric titration of acids and bases in dimethylsulfoxide media

    NARCIS (Netherlands)

    Bos, M.; IJpma, S.T.; Dahmen, E.A.M.F.

    1976-01-01

    The coulometric titration of 20–200 μeq of acids and bases in DMSO media is described. In the titration of bases, the electro-oxidation of hydrogen at a platinized platinum electrode is used as the source of protons. The conditions for 100 % current efficiency at this electrode are low current

  15. A European Acid Rain Program based on the US experience

    DEFF Research Database (Denmark)

    Brandt, U. Steiner; Svendsen, Gert Tinggaard

    2000-01-01

    The paper shows that cost-effective involvement of the source location involves utmost difficulty in practice. Based on the RAINS model, it is recommended that source location should be ignored in a European market for SO2, as is the case in the US Acid Rain Program. Based on the political target...

  16. Farnesyl pyrophosphate synthase enantiospecificity with a chiral risedronate analog, [6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl(hydroxy)methylene]bis(phosphonic acid) (NE-10501): Synthetic, structural, and modeling studies

    Energy Technology Data Exchange (ETDEWEB)

    Deprele, Sylvine; Kashemirov, Boris A.; Hogan, James M.; Ebetino, Frank H.; Barnett, Bobby L.; Evdokimov, Artem; McKenna, Charles E. (USC); (UCIN); (PG)

    2008-08-19

    The complex formed from crystallization of human farnesyl pyrophosphate synthase (hFPPS) from a solution of racemic [6,7-dihydro-5H-cyclopenta[c]pyridin-7-yl(hydroxy)methylene]bis(phosphonic acid) (NE-10501, 8), a chiral analog of the anti-osteoporotic drug risedronate, contained the R enantiomer in the enzyme active site. This enantiospecificity was assessed by computer modeling of inhibitor-active site interactions using Autodock 3, which was also evaluated for predictive ability in calculations of the known configurations of risedronate, zoledronate, and minodronate complexed in the active site of hFPPS. In comparison with these structures, the 8 complex exhibited certain differences, including the presence of only one Mg{sup 2+}, which could contribute to its 100-fold higher IC{sub 50}. An improved synthesis of 8 is described, which decreases the number of steps from 12 to 8 and increases the overall yield by 17-fold.

  17. Hard and soft acids and bases: atoms and atomic ions.

    Science.gov (United States)

    Reed, James L

    2008-07-07

    The structural origin of hard-soft behavior in atomic acids and bases has been explored using a simple orbital model. The Pearson principle of hard and soft acids and bases has been taken to be the defining statement about hard-soft behavior and as a definition of chemical hardness. There are a number of conditions that are imposed on any candidate structure and associated property by the Pearson principle, which have been exploited. The Pearson principle itself has been used to generate a thermodynamically based scale of relative hardness and softness for acids and bases (operational chemical hardness), and a modified Slater model has been used to discern the electronic origin of hard-soft behavior. Whereas chemical hardness is a chemical property of an acid or base and the operational chemical hardness is an experimental measure of it, the absolute hardness is a physical property of an atom or molecule. A critical examination of chemical hardness, which has been based on a more rigorous application of the Pearson principle and the availability of quantitative measures of chemical hardness, suggests that the origin of hard-soft behavior for both acids and bases resides in the relaxation of the electrons not undergoing transfer during the acid-base interaction. Furthermore, the results suggest that the absolute hardness should not be taken as synonymous with chemical hardness but that the relationship is somewhat more complex. Finally, this work provides additional groundwork for a better understanding of chemical hardness that will inform the understanding of hardness in molecules.

  18. Satellite-Based Thermophysical Analysis of Volcaniclastic Deposits: A Terrestrial Analog for Mantled Lava Flows on Mars

    Directory of Open Access Journals (Sweden)

    Mark A. Price

    2016-02-01

    Full Text Available Orbital thermal infrared (TIR remote sensing is an important tool for characterizing geologic surfaces on Earth and Mars. However, deposition of material from volcanic or eolian activity results in bedrock surfaces becoming significantly mantled over time, hindering the accuracy of TIR compositional analysis. Moreover, interplay between particle size, albedo, composition and surface roughness add complexity to these interpretations. Apparent Thermal Inertia (ATI is the measure of the resistance to temperature change and has been used to determine parameters such as grain/block size, density/mantling, and the presence of subsurface soil moisture/ice. Our objective is to document the quantitative relationship between ATI derived from orbital visible/near infrared (VNIR and thermal infrared (TIR data and tephra fall mantling of the Mono Craters and Domes (MCD in California, which were chosen as an analog for partially mantled flows observed at Arsia Mons volcano on Mars. The ATI data were created from two images collected ~12 h apart by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER instrument. The results were validated with a quantitative framework developed using fieldwork that was conducted at 13 pre-chosen sites. These sites ranged in grain size from ash-sized to meter-scale blocks and were all rhyolitic in composition. Block size and mantling were directly correlated with ATI. Areas with ATI under 2.3 × 10−2 were well-mantled with average grain size below 4 cm; whereas values greater than 3.0 × 10−2 corresponded to mantle-free surfaces. Correlation was less accurate where checkerboard-style mixing between mantled and non-mantled surfaces occurred below the pixel scale as well as in locations where strong shadowing occurred. However, the results validate that the approach is viable for a large majority of mantled surfaces on Earth and Mars. This is relevant for determining the volcanic history of Mars, for

  19. Investigation of Higher Brain Functions in Music Composition Using Models of the Cortex Based on Physical System Analogies.

    Science.gov (United States)

    Leng, Xiaodan

    The trion model was developed using the Mountcastle organizational principle for the column as the basic neuronal network in the cortex and the physical system analogy of Fisher's ANNNI spin model. An essential feature is that it is highly structured in time and in spatial connections. Simulations of a network of trions have shown that large numbers of quasi-stable, periodic spatial-temporal firing patterns can be excited. Characteristics of these patterns include the quality of being readily enhanced by only a small change in connection strengths, and that the patterns evolve in certain natural sequences from one to another. With only somewhat different parameters than used for studying memory and pattern recognition, much more flowing and intriguing patterns emerged from the simulations. The results were striking when these probabilistic evolutions were mapped onto pitches and instruments to produce music: For example different simple mappings of the same evolution give music having the "flavor" of a minuet, a waltz, folk music, or styles of specific periods. A theme can be learned so that evolutions have this theme and its variations reoccurring more often. That the trion model is a viable model for the coding of musical structure in human composition and perception is suggested. It is further proposed that model is relevant for examining creativity in the higher cognitive functions of mathematics and chess, which are similar to music. An even higher level of cortical organization was modeled by coupling together several trion networks. Further, one of the crucial features of higher brain function, especially in music composition or appreciation, is the role of emotion and mood as controlled by the many neuromodulators or neuropeptides. The MILA model whose underlying basis is zero-level representation of Kac-Moody algebra is used to modulate periodically the firing threshold of each network. Our preliminary results show that the introduction of "neuromodulation

  20. Ionic liquid supported acid/base-catalyzed production of biodiesel.

    Science.gov (United States)

    Lapis, Alexandre A M; de Oliveira, Luciane F; Neto, Brenno A D; Dupont, Jairton

    2008-01-01

    The transesterification (alcoholysis) reaction was successfully applied to synthesize biodiesel from vegetable oils using imidazolium-based ionic liquids under multiphase acidic and basic conditions. Under basic conditions, the combination of the ionic liquid 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (BMINTf2), alcohols, and K2CO3 (40 mol %) results in the production of biodiesel from soybean oil in high yields (>98%) and purity. H2SO4 immobilized in BMINTf2 efficiently promotes the transesterification reaction of soybean oil and various primary and secondary alcohols. In this multiphase process the acid is almost completely retained in the ionic liquid phase, while the biodiesel forms a separate phase. The recovered ionic liquid containing the acid could be reused at least six times without any significant loss in the biodiesel yield or selectivity. In both catalytic processes (acid and base), the reactions proceed as typical multiphasic systems in which the formed biodiesel accumulates as the upper phase and the glycerol by-product is selectively captured by the alcohol-ionic liquid-acid/base phase. Classical ionic liquids such as 1-n-butyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate are not stable under these acidic or basic conditions and decompose.

  1. Troubleshooting analog circuits

    CERN Document Server

    Pease, Robert A

    1991-01-01

    Troubleshooting Analog Circuits is a guidebook for solving product or process related problems in analog circuits. The book also provides advice in selecting equipment, preventing problems, and general tips. The coverage of the book includes the philosophy of troubleshooting; the modes of failure of various components; and preventive measures. The text also deals with the active components of analog circuits, including diodes and rectifiers, optically coupled devices, solar cells, and batteries. The book will be of great use to both students and practitioners of electronics engineering. Other

  2. A computational study of ultrafast acid dissociation and acid-base neutralization reactions. I. The model.

    Science.gov (United States)

    Maurer, Patrick; Thomas, Vibin; Rivard, Ugo; Iftimie, Radu

    2010-07-28

    Ultrafast, time-resolved investigations of acid-base neutralization reactions have recently been performed using systems containing the photoacid 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) and various Bronsted bases. Two conflicting neutralization mechanisms have been formulated by Mohammed et al. [Science 310, 83 (2005)] and Siwick et al. [J. Am. Chem. Soc. 129, 13412 (2007)] for the same acid-base system. Herein an ab initio molecular dynamics based computational model is formulated, which is able to investigate the validity of the proposed mechanisms in the general context of ground-state acid-base neutralization reactions. Our approach consists of using 2,4,6-tricyanophenol (exp. pKa congruent with 1) as a model for excited-state HPTS( *) (pKa congruent with 1.4) and carboxylate ions for the accepting base. We employ our recently proposed dipole-field/quantum mechanics (QM) treatment [P. Maurer and R. Iftimie, J. Chem. Phys. 132, 074112 (2010)] of the proton donor and acceptor molecules. This approach allows one to tune the free energy of neutralization to any desired value as well as model initial nonequilibrium hydration effects caused by a sudden increase in acidity, making it possible to achieve a more realistic comparison with experimental data than could be obtained via a full-QM treatment of the entire system. It is demonstrated that the dipole-field/QM model reproduces correctly key properties of the 2,4,6-tricyanophenol acid molecule including gas-phase proton dissociation energies and dipole moments, and condensed-phase hydration structure and pKa values.

  3. Deoxyribonucleic acid base compositions of dermatophytes.

    Science.gov (United States)

    Davison, F D; Mackenzie, D W; Owen, R J

    1980-06-01

    DNA was extracted and purified from 55 dermatophyte isolates representing 34 species of Trichophyton, Microsporum and Epidermophyton. The base compositions of the chromosomal DNA were determined by CsCl density gradient centrifugation and were found to be in the narrow range of 48.7 to 50.3 mol % G + C. A satellite DNA component assumed to be of mitochondrial origin was present in most strains, with a G + C content ranging from 14.7 to 30.8 mol % G + C. Heterogeneity in microscopic and colonial characteristics was not reflected in differences in the mean G + C content of the chromosomal DNAs. Strains varied in the G + C contents of satelite DNA, but these did not correlate with traditional species concepts.

  4. All-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an analog on the electromagnetically induced transparency effect

    Science.gov (United States)

    Wang, Boyun; Xiong, Liangbin; Zeng, Qingdong; Chen, Zhihong; Lv, Hao; Ding, Yaoming; Du, Jun; Yu, Huaqing

    2016-06-01

    We theoretically and numerically investigate all-optical Mach-Zehnder interferometer switching based on the phase-shift multiplication effect of an all-optical analog on the electromagnetically induced transparency effect. The free-carrier plasma dispersion effect modulation method is applied to improve the tuning rate with a response time of picoseconds. All observed schemes are analyzed rigorously through finite-difference time-domain simulations and coupled-mode formalism. Compared with no phase-shift multiplication effect, the average pump power of all-optical switching required to yield the π-phase shift difference decreases by 55.1%, and the size of the modulation region is reduced by 50.1% when the average pump power reaches 60.8 mW. This work provides a new direction for low-power consumption and miniaturization of microstructure integration light-controlled switching devices in optical communication and quantum information processing.

  5. Structure-based design, synthesis and biological testing of etoposide analog epipodophyllotoxin-N-mustard hybrid compounds designed to covalently bind to topoisomerase II and DNA.

    Science.gov (United States)

    Yadav, Arun A; Wu, Xing; Patel, Daywin; Yalowich, Jack C; Hasinoff, Brian B

    2014-11-01

    Drugs that target DNA topoisomerase II isoforms and alkylate DNA represent two mechanistically distinct and clinically important classes of anticancer drugs. Guided by molecular modeling and docking a series of etoposide analog epipodophyllotoxin-N-mustard hybrid compounds were designed, synthesized and biologically characterized. These hybrids were designed to alkylate nucleophilic protein residues on topoisomerase II and thus produce inactive covalent adducts and to also alkylate DNA. The most potent hybrid had a mean GI(50) in the NCI-60 cell screen 17-fold lower than etoposide. Using a variety of in vitro and cell-based assays all of the hybrids tested were shown to target topoisomerase II. A COMPARE analysis indicated that the hybrids had NCI 60-cell growth inhibition profiles matching both etoposide and the N-mustard compounds from which they were derived. These results supported the conclusion that the hybrids displayed characteristics that were consistent with having targeted both topoisomerase II and DNA.

  6. A High-Resolution Transmission-Type (TT) Phaser Based on Reflection-Type (RT) Units for Radio Analog Signal Processing (R-ASP)

    CERN Document Server

    Zou, Lianfeng

    2014-01-01

    A high Radio Analog Signal Processing (R-ASP) resolution transmission-type (TT) phaser based on reflection-type (RT) phaser units is introduced, theoretically studied and experimentally demonstrated. It is first shown that RT phasers inherently exhibit higher R-ASP resolution than their TT counterparts because their group delay swing is proportional to the reflection coefficient associated with a resonator coupling mechanism (admittance inverter), easy to maximize towards unity, rather than to a coupled-line coupling coefficient, typically restricted to values will inferior to unity, as in the RT case. Moreover, a detailed sensitivity analysis reveals that the proposed phaser is simultaneously features high R-ASP resolution and low sensitivity to fabrication tolerance, which makes it an ideal solution for R-ASP. The proposed phaser exhibits a 5 ns group delay swing over a fractional bandwidth of about 50% around 4 GHz.

  7. Effect of the back bias on the analog performance of standard FD and UTBB transistors-based self-cascode structures

    Science.gov (United States)

    Doria, Rodrigo T.; Flandre, Denis; Trevisoli, Renan; de Souza, Michelly; Pavanello, Marcelo A.

    2017-09-01

    This work demonstrates that active back biasing can improve significantly the analog performance of two-transistors self-cascode structures. The study was performed by applying both standard and UTBB fully depleted (FD) SOI MOSFETs to the structures and has shown that a voltage gain improvement of about 7 dB is obtained when a forward back bias is applied to the drain-sided transistor of standard FD devices-based structure. In the case of UTBB transistors, an improvement larger than 5 dB of the output voltage gain is shown depending on the back bias applied to both n- or p-type devices. Finally, it is shown that the mirroring precision of current mirrors composed by SC structures can be more than 20% better than the one composed by single devices and the improvement is better when adequate back bias is applied.

  8. Astrobionibbler: In Situ Microfluidic Subcritical Water Extraction of Amino Acids

    Science.gov (United States)

    Noell, A. C.; Fisher, A. M.; Takano, N.; Fors-Francis, K.; Sherrit, S.; Grunthaner, F.

    2016-10-01

    A fluidic-chip based instrument for subcritical water extraction (SCWE) of amino acids and other organics from powder samples has been developed. A variety of soil analog extractions have been performed to better understand SCWE capabilities.

  9. Micelle-bound structures and dynamics of the hinge deleted analog of melittin and its diastereomer: implications in cell selective lysis by D-amino acid containing antimicrobial peptides.

    Science.gov (United States)

    Saravanan, Rathi; Bhunia, Anirban; Bhattacharjya, Surajit

    2010-02-01

    Melittin, the major component of the honey bee venom, is a 26-residue hemolytic and membrane active peptide. Structures of melittin determined either in lipid environments by NMR or by use of X-ray demonstrated two helical regions at the N- and C-termini connected by a hinge or a bend at the middle. Here, we show that deletion of the hinge residues along with two C-terminal terminal Gln residues (Q25 and Q26), yielding a peptide analog of 19-residue or Mel-H, did not affect antibacterial activity but resulted in a somewhat reduced hemolytic activity. A diastereomer of Mel-H or Mel-(d)H containing d-amino acids [(d)V5, (d)V8, (d)L11 and (d)K16] showed further reduction in hemolytic activity without lowering antibacterial activity. We have carried out NMR structures, dynamics (H-D exchange and proton relaxation), membrane localization by spin labeled lipids, pulse-field-gradient (PFG) NMR and isothermal titration calorimetry (ITC) in dodecylphosphocholine (DPC) micelles, as a mimic to eukaryotic membrane, to gain insights into cell selectivity of these melittin analogs. PFG-NMR showed Mel-H and Mel-(d)H both were similarly partitioned into DPC micelles. ITC demonstrated that Mel-H and Mel-(d)H interact with DPC with similar affinity. The micelle-bound structure of Mel-H delineated a straight helical conformation, whereas Mel-(d)H showed multiple beta-turns at the N-terminus and a short helix at the C-terminus. The backbone amide-proton exchange with solvent D(2)O demonstrated a large difference in dynamics between Mel-H and Mel-(d)H, whereby almost all backbone protons of Mel-(d)H showed a much faster rate of exchange as compared to Mel-H. Proton T(1) relaxation had suggested a mobile backbone of Mel-(d)H peptide in DPC micelles. Resonance perturbation by paramagnetic lipids indicated that Mel-H inserted deeper into DPC micelles, whereas Mel-(d)H is largely located at the surface of the micelle. Taken together, results presented in this study demonstrated that the

  10. Synthesis and characterization of boric acid mediated metal-organic frameworks based on trimesic acid and terephthalic acid

    Science.gov (United States)

    Ozer, Demet; Köse, Dursun A.; Şahin, Onur; Oztas, Nursen Altuntas

    2017-08-01

    The new metal-organic framework materials based on boric acid reported herein. Sodium and boron containing metal-organic frameworks were synthesized by one-pot self-assembly reaction in the presence of trimesic acid and terephthalic acid in water/ethanol solution. Boric acid is a relatively cheap boron source and boric acid mediated metal-organic framework prepared mild conditions compared to the other boron source based metal-organic framework. The synthesized compounds were characterized by FT-IR, p-XRD, TGA/DTA, elemental analysis, 13C-MAS NMR, 11B-NMR and single crystal measurements. The molecular formulas of compounds were estimated as C18H33B2Na5O28 and C8H24B2Na2O17 according to the structural analysis. The obtained complexes were thermally stable. Surface properties of inorganic polymer complexes were investigated by BET analyses and hydrogen storage properties of compound were also calculated.

  11. TV Analog Station Transmitters

    Data.gov (United States)

    Department of Homeland Security — This file is an extract from the Consolidated Database System (CDBS) licensed by the Media Bureau. It consists of Analog Television Stations (see Rule Part47 CFR...

  12. Analog multivariate counting analyzers

    CERN Document Server

    Nikitin, A V; Armstrong, T P

    2003-01-01

    Characterizing rates of occurrence of various features of a signal is of great importance in numerous types of physical measurements. Such signal features can be defined as certain discrete coincidence events, e.g. crossings of a signal with a given threshold, or occurrence of extrema of a certain amplitude. We describe measuring rates of such events by means of analog multivariate counting analyzers. Given a continuous scalar or multicomponent (vector) input signal, an analog counting analyzer outputs a continuous signal with the instantaneous magnitude equal to the rate of occurrence of certain coincidence events. The analog nature of the proposed analyzers allows us to reformulate many problems of the traditional counting measurements, and cast them in a form which is readily addressed by methods of differential calculus rather than by algebraic or logical means of digital signal processing. Analog counting analyzers can be easily implemented in discrete or integrated electronic circuits, do not suffer fro...

  13. Discovery and SARs of trans-3-aryl acrylic acids and their analogs as novel anti-tobacco mosaic virus (TMV) agents.

    Science.gov (United States)

    Wu, Meng; Wang, Ziwen; Meng, Chuisong; Wang, Kailiang; Hu, Yanna; Wang, Lizhong; Wang, Qingmin

    2013-01-01

    A series of trans-3-aryl acrylic acids 1-27 and their derivatives 28-34 were prepared and evaluated for their antiviral activity against tobacco mosaic virus (TMV) for the first time. The bioassay results showed that most of these compounds exhibited good antiviral activity against TMV, of which compounds 1, 5, 6, 20, 27 and 34 exhibited significantly higher activity against TMV than commercial Ribavirin both in vitro and in vivo. Furthermore, these compounds have more simple structure than commercial Ribavirin, and can be synthesized more efficiently. These new findings demonstrate that trans-3-aryl acrylic acids and their derivatives represent a new template for antiviral studies and could be considered for novel therapy against plant virus infection.

  14. Discovery and SARs of trans-3-aryl acrylic acids and their analogs as novel anti-tobacco mosaic virus (TMV agents.

    Directory of Open Access Journals (Sweden)

    Meng Wu

    Full Text Available A series of trans-3-aryl acrylic acids 1-27 and their derivatives 28-34 were prepared and evaluated for their antiviral activity against tobacco mosaic virus (TMV for the first time. The bioassay results showed that most of these compounds exhibited good antiviral activity against TMV, of which compounds 1, 5, 6, 20, 27 and 34 exhibited significantly higher activity against TMV than commercial Ribavirin both in vitro and in vivo. Furthermore, these compounds have more simple structure than commercial Ribavirin, and can be synthesized more efficiently. These new findings demonstrate that trans-3-aryl acrylic acids and their derivatives represent a new template for antiviral studies and could be considered for novel therapy against plant virus infection.

  15. Acid-base patterns in acute severe asthma.

    Science.gov (United States)

    Raimondi, Guillermo A; Gonzalez, Silvia; Zaltsman, Jorge; Menga, Guillermo; Adrogué, Horacio J

    2013-12-01

    Acid-base status in acute severe asthma (ASA) remains undefined; some studies report complete absence of metabolic acidosis, whereas others describe it as present in one fourth of patients or more. Conclusion discrepancies would therefore appear to derive from differences in assessment methodology. Only a systematic approach centering on patient clinical findings can correctly establish true acid-base disorder prevalence levels. This study examines acid-base patterns in ASA (314 patients), taking into account both natural history of disease and treatment, in patients free of other diseases altering acid-base status. Data were collected from patients admitted for ASA without prior history of chronic bronchitis, emphysema, kidney or liver disease, heart failure, uncontrolled diabetes mellitus or gastrointestinal illness. Informed consent was obtained for all patients, after study protocol approval by the Institutional Review Board. Arterial blood gases, plasma electrolytes, lactate levels, and FEV(1) were measured on arrival. Severe airway obstruction was found with FEV(1) values of 25.6 ± 10.0%, substantial hypoxemia (PaO(2) 66.1 ± 11.9 mmHg) and increased A-a O(2) gradient (39.3 ± 12.3 mmHg) breathing room air. While respiratory alkalosis occurred in patients with better preservation of FEV1, respiratory acidosis was observed with more severe airway obstruction, as was increased lactate in the majority of patients, independent of PaO(2) and PaCO(2) levels. Predominant acid-base patterns observed in ASA in this patient population included primary hypocapnia, or less frequently, primary hypercapnia. Lactic acidosis occurred in 11% of patients and presented consistently as a mixed acid-base disorder. These findings suggest lactic acidosis results from the combined effects of both ASA and medication-related sympathetic effects.

  16. Regulated acid-base transport in the collecting duct.

    Science.gov (United States)

    Wagner, Carsten A; Devuyst, Olivier; Bourgeois, Soline; Mohebbi, Nilufar

    2009-05-01

    The renal collecting system serves the fine-tuning of renal acid-base secretion. Acid-secretory type-A intercalated cells secrete protons via a luminally expressed V-type H(+)-ATPase and generate new bicarbonate released by basolateral chloride/bicarbonate exchangers including the AE1 anion exchanger. Efficient proton secretion depends both on the presence of titratable acids (mainly phosphate) and the concomitant secretion of ammonia being titrated to ammonium. Collecting duct ammonium excretion requires the Rhesus protein RhCG as indicated by recent KO studies. Urinary acid secretion by type-A intercalated cells is strongly regulated by various factors among them acid-base status, angiotensin II and aldosterone, and the Calcium-sensing receptor. Moreover, urinary acidification by H(+)-ATPases is modulated indirectly by the activity of the epithelial sodium channel ENaC. Bicarbonate secretion is achieved by non-type-A intercalated cells characterized by the luminal expression of the chloride/bicarbonate exchanger pendrin. Pendrin activity is driven by H(+)-ATPases and may serve both bicarbonate excretion and chloride reabsorption. The activity and expression of pendrin is regulated by different factors including acid-base status, chloride delivery, and angiotensin II and may play a role in NaCl retention and blood pressure regulation. Finally, the relative abundance of type-A and non-type-A intercalated cells may be tightly regulated. Dysregulation of intercalated cell function or abundance causes various syndromes of distal renal tubular acidosis underlining the importance of these processes for acid-base homeostasis.

  17. Synthesis of Paclitaxel Analogs

    OpenAIRE

    Xu, Zhibing

    2010-01-01

    Paclitaxel is one of the most successful anti-cancer drugs, particularly in the treatment of breast cancer and ovarian cancer. For the investigation of the interaction between paclitaxel and MD-2 protein, and development of new antagonists for lipopolysaccharide, several C10 A-nor-paclitaxel analogs have been synthesized and their biological activities have been evaluated. In order to reduce the myelosuppression effect of the paclitaxel, several C3â ² and C4 paclitaxel analogs have been synth...

  18. FGF growth factor analogs

    Science.gov (United States)

    Zamora, Paul O [Gaithersburg, MD; Pena, Louis A [Poquott, NY; Lin, Xinhua [Plainview, NY; Takahashi, Kazuyuki [Germantown, MD

    2012-07-24

    The present invention provides a fibroblast growth factor heparin-binding analog of the formula: ##STR00001## where R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, X, Y and Z are as defined, pharmaceutical compositions, coating compositions and medical devices including the fibroblast growth factor heparin-binding analog of the foregoing formula, and methods and uses thereof.

  19. Analog circuits cookbook

    CERN Document Server

    Hickman, Ian

    2013-01-01

    Analog Circuits Cookbook presents articles about advanced circuit techniques, components and concepts, useful IC for analog signal processing in the audio range, direct digital synthesis, and ingenious video op-amp. The book also includes articles about amplitude measurements on RF signals, linear optical imager, power supplies and devices, and RF circuits and techniques. Professionals and students of electrical engineering will find the book informative and useful.

  20. Troger's base molecular scaffolds in dicarboxylic acid recognition.

    Science.gov (United States)

    Goswami, S; Ghosh, K; Dasgupta, S

    2000-04-07

    Artificial receptors (1-5) have been designed and synthesized from simple precursors. The chain length selectivity studies of dicarboxylic acids within the cavities of new fluorescent Troger's base molecular frameworks (1-3) have been carried out with a critical examination of their role of rigidity as well as flexibility in selective binding in comparison to receptor 5. The chiral resolution of the racemic Troger's base receptors (1 and 2) by chiral recognition with (+)- camphoric acid using hydrogen-bonding interactions has been studied.

  1. Carbon Dot Based Sensing of Dopamine and Ascorbic Acid

    Directory of Open Access Journals (Sweden)

    Upama Baruah

    2014-01-01

    Full Text Available We demonstrate carbon dot based sensor of catecholamine, namely, dopamine and ascorbic acid. Carbon dots (CDs were prepared from a green source: commercially available Assam tea. The carbon dots prepared from tea had particle sizes of ∼0.8 nm and are fluorescent. Fluorescence of the carbon dots was found to be quenched in the presence of dopamine and ascorbic acid with greater sensitivity for dopamine. The minimum detectable limits were determined to be 33 μM and 98 μM for dopamine and ascorbic acid, respectively. The quenching constants determined from Stern-Volmer plot were determined to be 5 × 10−4 and 1 × 10−4 for dopamine and ascorbic acid, respectively. A probable mechanism of quenching has been discussed in the paper.

  2. A computational model of analogical reasoning

    Institute of Scientific and Technical Information of China (English)

    李波; 赵沁平

    1997-01-01

    A computational model of analogical reasoning is presented, which divides analogical reasoning process into four subprocesses, i.e. reminding, elaboration, matching and transfer. For each subprocess, its role and the principles it follows are given. The model is discussed in detail, including salient feature-based reminding, relevance-directed elaboration, an improved matching model and a transfer model. And the advantages of this model are summarized based on the results of BHARS, which is an analogical reasoning system implemented by this model.

  3. Relativistic effects on acidities and basicities of Brønsted acids and bases containing gold.

    Science.gov (United States)

    Koppel, Ilmar A; Burk, Peeter; Kasemets, Kalev; Koppel, Ivar

    2013-11-07

    It is usually believed that relativistic effects as described by the Dirac-Schrödinger equation (relative to the classical or time-independent Schrödinger equation) are of little importance in chemistry. A closer look, however, reveals that some important and widely known properties (e.g., gold is yellow, mercury is liquid at room temperature) stem from relativistic effects. So far the influence of relativistic effects on the acid-base properties has been mostly ignored. Here we show that at least for compounds of gold such omission is completely erroneous and would lead to too high basicity and too low acidity values with errors in the range of 25-55 kcal mol(-1) (or 20 to 44 powers of ten in pK(a) units) in the gas-phase. These findings have important implications for the design of new superstrong acids and bases, and for the understanding of gold-catalysed reactions.

  4. 100 gigasamples per second 12 bits optoelectronic analog-to-digital converter design and implementation based on cellular polyphase-sampling architecture

    Science.gov (United States)

    Villa-Angulo, Carlos

    The next generation digital information systems such as high performance computers, multigigabit/sec communication networks, distributed sensors, three dimensional digital imaging systems etc, will require analog-to-digital converters (ADCs) with high sampling rates exceeding 10 Gigasamples per second (GSPS) and high bit resolution of at least 10 bits. Such performance criteria are difficult to achieve with silicon electronics technology because the switching speeds peak at about 10-20GHz. Also, timing jitters, amplitude fluctuations, phase noise, thermal noise, and harmonic distortion, all contribute to reductions in ADC bit resolution as sampling rate increases. Photonics ADCs are rapidly emerging as the enabling technologies for high-performance digital signal processing systems. For this technology, high optical pulses repetition rate (in the order of GHz) with low time jitter and pulse width in the femtoseconds regime are the major attractive characteristics of optical sources. In this dissertation work, a novel 102.4 GSPS 12-bit optoelectronic analog-to-digital converter architecture that is based on a Cellular Polyphase-Sampling architecture is introduced. First, a 102.4 GHz all-optical clock was designed and implemented using a femtosecond laser source and passive optical components. Second, a novel optoelectronic architecture for optical sampling and parallel demultiplexing of different phases (polyphase) of an input analog signal is presented. The optoelectronic sampling and demultiplexing architecture is composed by 20 optoelectronic subcircuit referred as "OE-Cell"; these have been designed and implemented using optical passive components and InGaAs PIN photodiodes. A unique feature of this approach is that the optically sampled RF signal always remains in the electrical domain and thus eliminates the need for electrical-to-optical and optical-to-electrical conversions. The electrical-in to electrical-out transfer functions of the sampling and

  5. Low Power CMOS Analog Multiplier

    Directory of Open Access Journals (Sweden)

    Shipra Sachan

    2015-12-01

    Full Text Available In this paper Low power low voltage CMOS analog multiplier circuit is proposed. It is based on flipped voltage follower. It consists of four voltage adders and a multiplier core. The circuit is analyzed and designed in 0.18um CMOS process model and simulation results have shown that, under single 0.9V supply voltage, and it consumes only 31.8µW quiescent power and 110MHZ bandwidth.

  6. Electrical Circuits and Water Analogies

    Science.gov (United States)

    Smith, Frederick A.; Wilson, Jerry D.

    1974-01-01

    Briefly describes water analogies for electrical circuits and presents plans for the construction of apparatus to demonstrate these analogies. Demonstrations include series circuits, parallel circuits, and capacitors. (GS)

  7. A knowledge based advisory system for acid/base titrations in non-aqueous solvents

    NARCIS (Netherlands)

    Bos, M.; Linden, van der W.E.

    1996-01-01

    A computer program was developed that could advice on the choice of solvent and titrant for acid/base titrations in nonaqueous media. It is shown that the feasibility of a titration in a given solvent can be calculated from solvent properties and intrinsic acid/base properties of the sample componen

  8. Design of cinnamaldehyde amino acid Schiff base compounds based on the quantitative structure–activity relationship

    Science.gov (United States)

    Hui Wang; Mingyue Jiang; Shujun Li; Chung-Yun Hse; Chunde Jin; Fangli Sun; Zhuo Li

    2017-01-01

    Cinnamaldehyde amino acid Schiff base (CAAS) is a new class of safe, bioactive compounds which could be developed as potential antifungal agents for fungal infections. To design new cinnamaldehyde amino acid Schiff base compounds with high bioactivity, the quantitative structure–activity relationships (QSARs) for CAAS compounds against Aspergillus niger (A. niger) and...

  9. The Effect of Mini-PEG-Based Spacer Length on Binding and Pharmacokinetic Properties of a 68Ga-Labeled NOTA-Conjugated Antagonistic Analog of Bombesin

    Directory of Open Access Journals (Sweden)

    Zohreh Varasteh

    2014-07-01

    Full Text Available The overexpression of gastrin-releasing peptide receptor (GRPR in cancer can be used for peptide-receptor mediated radionuclide imaging and therapy. We have previously shown that an antagonist analog of bombesin RM26 conjugated to 1,4,7-triazacyclononane-N,N',N''-triacetic acid (NOTA via a diethyleneglycol (PEG2 spacer (NOTA-PEG2-RM26 and labeled with 68Ga can be used for imaging of GRPR-expressing tumors. In this study, we evaluated if a variation of mini-PEG spacer length can be used for optimization of targeting properties of the NOTA-conjugated RM26. A series of analogs with different PEG-length (n = 2, 3, 4, 6 was synthesized, radiolabeled and evaluated in vitro and in vivo. The IC50 values of natGa-NOTA-PEGn-RM26 (n = 2, 3, 4, 6 were 3.1 ± 0.2, 3.9 ± 0.3, 5.4 ± 0.4 and 5.8 ± 0.3 nM, respectively. In normal mice all conjugates demonstrated similar biodistribution pattern, however 68Ga-NOTA-PEG3-RM26 showed lower liver uptake. Biodistribution of 68Ga-NOTA-PEG3-RM26 was evaluated in nude mice bearing PC-3 (prostate cancer and BT-474 (breast cancer xenografts. High uptake in tumors (4.6 ± 0.6%ID/g and 2.8 ± 0.4%ID/g for PC-3 and BT-474 xenografts, respectively and high tumor-to-background ratios (tumor/blood of 44 ± 12 and 42 ± 5 for PC-3 and BT-474 xenografts, respectively were found already at 2 h p.i. of 68Ga-NOTA-PEG3-RM26. Results of this study suggest that variation in the length of the PEG spacer can be used for optimization of targeting properties of peptide-chelator conjugates. However, the influence of the mini-PEG length on biodistribution is minor when di-, tri-, tetra- and hexaethylene glycol are compared.

  10. Potential development and recharge of ground water in Mill Creek Valley, Butler and Hamilton Counties, Ohio, based on analog model analysis

    Science.gov (United States)

    Fidler, Richard E.

    1971-01-01

    Mill Creek valley is part of the greater Cincinnati industrial area in southwestern Ohio. In 1964, nearly 30 percent of the water supply in the study area of about 27 square miles was obtained from wells in the glacial-outwash aquifer underlying the valley. Ground-water demand has increased steadily since the late 1800's, and excessive pumpage during the years of World War II caused water levels to decline to critical levels. Natural recharge to the aquifer, from precipitation, is about 8.5 mgd (million gallons per day). In 1964, the total water use was about 30 mgd, of which 8.1 mgd was obtained from wells in Mill Creek valley, and the remainder was imported from outside the basin. With rapid industrial expansion and population growth, demand for ground water is continuing to increase. By the year 2000 ground-water pumpage is expected to exceed 25 mgd. At a public hearing before the Ohio Water Commission in 1961, artificial recharge of the aquifer through injection wells was proposed as a possible solution to the Mill Creek valley water-supply problem. The present study attempts to determine the feasibility of injection-well recharge systems in the Mill Creek valley. Although basically simple, the hydrologic system in Mill Creek valley is complex in detail and is difficult to evaluate using conventional quantitative methods. Because of this complexity, an electric analog model was used to test specific development plans. Three hypothetical pumping plans were developed by projecting past pumpage data to the years 1980 and 2000. Various combinations of injection wells were tested on the model under different hypothetical conditions of pumpage. Based on analog model analysis, from three to eight inject-ion wells, with an approximate input of 2 mgd each, would reverse the trend in declining groundwater levels and provide adequate water to meet anticipated future demands.

  11. Novel acyclonucleoside analog bearing a 1,2,4-triazole–Schiff base: Synthesis, characterization and analytical studies using square wave-adsorptive stripping voltammetry and HPLC

    Directory of Open Access Journals (Sweden)

    Ali F. Alghamdi

    2017-09-01

    Full Text Available New acyclonucleoside analogs tethered by a 1,2,4-triazole scaffold were synthesized through the condensation of 4-amino-5-(2-phenyleth-1-yl-2,4-dihydro-3H-1,2,4-triazole-3-thione (2 with benzaldehyde followed by the alkylation of the resulting Schiff base (3with 2-bromoethanol, 3-chloropropanol and/or 3-chloropropan-1,2-diol. Voltammetric studies were carried out for the analysis of 1 × 10−6 mol L−1 of the newly synthesized acyclonucleoside analogs (4–6 using square wave-adsorptive stripping voltammetry (SW-AdSV. The sharp voltammetric peak and high reduction current were recorded using a Britton–Robinson B–R pH 10 buffer at Ep = −1250 mV on the hanging mercury drop surface (HMDE and Ag/AgCl reference electrode. Several experimental conditions were studied, such as the supporting electrolytes, the pH, and the accumulation time, as well as the potential, the scan rate, the frequency and the step potential for 4-benzylideneamino-5-(2-phenyleth-1-yl-3-[(2,3-dihydroxyprop-1-ylthio]-1,2,4-triazole (6. The analytical performance of the voltammetric technique was investigated through the analysis of the calibration curve, the detection limit, the recovery and the stability. The voltammetric analytical applications were evaluated by the recovery of compound (6 in the urine and plasma samples. The HPLC technique was also applied for the separation of compound (6 from interference using a C-18 (5 μm column with UV detection at 254 nm.

  12. Influence of Iron on Production of the Antibacterial Compound Tropodithietic Acid and Its Noninhibitory Analog in Phaeobacter inhibens

    DEFF Research Database (Denmark)

    D'Alvise, Paul W; Phippen, Christopher B W; Nielsen, Kristian Fog

    2016-01-01

    , and Phaeobacter sp. strain 27-4 under low-iron concentrations and was instantaneously converted to TDA when pH was lowered. Production of TDA in the presence of Fe3+ coincides with formation of a dark brown substance, which could be precipitated by acid addition. From this brown pigment TDA could be liberated...... slowly with aqueous ammonia, and both direct-infusion mass spectrometry and elemental analysis indicated a [FeIII(TDA)2]x complex. The pigment could also be produced by precipitation of pure TDA with FeCl3. Our results raise questions about how biologically active TDA is produced in natural marine...

  13. Two-zone SiGe base heterojunction bipolar charge plasma transistor for next generation analog and RF applications

    Science.gov (United States)

    Bramhane, Lokesh Kumar; Singh, Jawar

    2017-01-01

    For next generation terahertz applications, heterojunction bipolar transistor (HBT) with reduced dimensions and charge plasma (CP) can be a potential candidate due to simplified and inexpensive process. In this paper, a symmetric lateral two-zone SiGe base heterojunction bipolar charge plasma transistor (HBCPT) with an extruded (extended) base is proposed and its performance at circuit level is studied. The linearly graded electric field in the proposed HBCPT provides improved self gain (β) and cut-off frequency (fT). Two-dimensional (2-D) TCAD and small-signal model based simulations of the proposed HBCPT demonstrates high self gain β 35-172.93 and fT of 1-4 THz for different device parameters. Moreover, fT of 1104.9 GHz and β of 35 can be achieved by decreasing Nb up to 8.2 ×1017cm-3 . Although, fT of 2 THz and 4 THz can also be achieved by reducing the base resistance up to 10 Ω and increasing the emitter/collector length up to 63 nm, respectively. The small-signal analysis of common-emitter amplifier based on the proposed HBCPT demonstrate high voltage gain of 50.11 as compared to conventional HBT (18.1).

  14. Acid-base transport in pancreas-new challenges

    DEFF Research Database (Denmark)

    Novak, Ivana; Haanes, Kristian Agmund; Wang, Jing

    2013-01-01

    Along the gastrointestinal tract a number of epithelia contribute with acid or basic secretions in order to aid digestive processes. The stomach and pancreas are the most extreme examples of acid (H+) and base (HCO-3) transporters, respectively. Nevertheless, they share the same challenges...... to consider in pancreas are the proton pumps (H-K-ATPases), as well as the calcium-activated K and Cl channels, such as K3.1 and TMEM16A/ANO1. Local regulators, such as purinergic signaling, fine-tune, and coordinate pancreatic secretion. Lastly, we speculate whether dys-regulation of acid-base transport...... contributes to pancreatic diseases including cystic fibrosis, pancreatitis, and cancer. © 2013 Novak, Haanes and Wang....

  15. Molecular mechanisms of acid-base sensing by the kidney.

    Science.gov (United States)

    Brown, Dennis; Wagner, Carsten A

    2012-05-01

    A major function of the kidney is to collaborate with the respiratory system to maintain systemic acid-base status within limits compatible with normal cell and organ function. It achieves this by regulating the excretion and recovery of bicarbonate (mainly in the proximal tubule) and the secretion of buffered protons (mainly in the distal tubule and collecting duct). How proximal tubular cells and distal professional proton transporting (intercalated) cells sense and respond to changes in pH, bicarbonate, and CO(2) status is a question that has intrigued many generations of renal physiologists. Over the past few years, however, some candidate molecular pH sensors have been identified, including acid/alkali-sensing receptors (GPR4, InsR-RR), kinases (Pyk2, ErbB1/2), pH-sensitive ion channels (ASICs, TASK, ROMK), and the bicarbonate-stimulated adenylyl cyclase (sAC). Some acid-sensing mechanisms in other tissues, such as CAII-PDK2L1 in taste buds, might also have similar roles to play in the kidney. Finally, the function of a variety of additional membrane channels and transporters is altered by pH variations both within and outside the cell, and the expression of several metabolic enzymes are altered by acid-base status in parts of the nephron. Thus, it is possible that a master pH sensor will never be identified. Rather, the kidney seems equipped with a battery of molecules that scan the epithelial cell environment to mount a coordinated physiologic response that maintains acid-base homeostasis. This review collates current knowledge on renal acid-base sensing in the context of a whole organ sensing and response process.

  16. Synthesis and Evaluation of Optical 2-Benzyl-5-bromo-4- oxopentanoic Acids as Transition-state Analog Inhibitors against Carboxypeptidase A

    Institute of Scientific and Technical Information of China (English)

    JIN,Jing-Yi; WANG,Shou-Feng; XUAN,Wei; SHENG,Ji-Wen; WANG,Si-Hong; TIAN,Guan-Rong

    2008-01-01

    Both enantiomers of 2-benzyl-5-bromo-4-oxopentanoic acid were prepared utilizing the diazo ketones as the key intermediates. The compounds were assayed for inhibitory activity against carboxypeptidase A (CPA, EC 3.4.17.1). The (R)-form is 260-fold more potent than the corresponding (S)-form. The finding that (R)-form, which belongs to the L-series, is mostly responsible for the inhibitory activity accords with the substrate specificity of CPA.For comparison, both the optical forms of 2-benzyl-4-oxopentanoic acid were also synthesized and evaluated as the inhibitors against CPA. These results reveal that the introduction of a bromo group at the α-position of ketones can significantly enhance the electrophilicity of the carbonyl group. Further molecular docking study suggested that the gem-diol form of the α-bromo ketone, which mimics the transition state in the CPA catalytic process, could chelate the zinc ion in the active site of CPA and thus result in the strong inhibition.

  17. The Role of Causal Models in Analogical Inference

    Science.gov (United States)

    Lee, Hee Seung; Holyoak, Keith J.

    2008-01-01

    Computational models of analogy have assumed that the strength of an inductive inference about the target is based directly on similarity of the analogs and in particular on shared higher order relations. In contrast, work in philosophy of science suggests that analogical inference is also guided by causal models of the source and target. In 3…

  18. Josephson junction analog and quasiparticle-pair current

    DEFF Research Database (Denmark)

    Bak, Christen Kjeldahl; Pedersen, Niels Falsig

    1973-01-01

    A close analogy exists between a Josephson junction and a phase-locked loop. A new type of electrical analog based on this principle is presented. It is shown that the inclusion in this analog of a low-pass filter gives rise to a current of the same form as the Josephson quasiparticle-pair current...

  19. A taxonomy-based approach to shed light on the babel of mathematical analogies for rice simulation

    Science.gov (United States)

    For most biophysical domains, different models are available and the extent to which their structures differ with respect to differences in outputs was never quantified. We use a taxonomy-based approach to address the question with thirteen rice models. Classification keys and binary attributes for ...

  20. Intramolecular hydrogen bond between 4-oxo and 3-carboxylic groups in quinolones and their analogs. Crystal structures of 7-methyl- and 6-fluoro-1,4-dihydro-4-oxocinnoline-3-carboxylic acids

    Science.gov (United States)

    Główka, Marek L.; Martynowski, Dariusz; Olczak, Andrzej; Bojarska, Joanna; Szczesio, Małgorzata; Kozłowska, Krystyna

    2003-09-01

    Crystal structures of two cinnoline analogs of quinolones and statistics on quinolones molecular forms observed in the crystal state have been determined. It has been shown that common quinolones may be divided into two main types, depending on presence of proton acceptor, usually aliphatic amine group, capable of protonation under mild conditions. Quinolones lacking amine group or having one(s) bound to an aromatic system exist at physiological pH mainly in a free acid form, in which acidic hydrogen atom is locked into an intramolecular hydrogen bond. The phenomenon enhances permeability of quinolones through lipophilic cell membranes but decreases the concentration of carboxylate form capable of specific binding with bacterial DNA. Molecular (neutral) form was observed exclusively in the crystalline state for these quinolones. The dominant forms seem different for quinolones having amine substituents with unconjugated lone pair electrons at N atom. Even in the crystalline state, they may exist also in a zwitterionic form, which was found to dominate in secondary amines crystallised at neutral pH. Our limited data suggest that position and order of amine group may play important role in controlling quinolones absorption, transport and concentration and thus their biological profile.

  1. Acid-base metabolism: implications for kidney stones formation.

    Science.gov (United States)

    Hess, Bernhard

    2006-04-01

    The physiology and pathophysiology of renal H+ ion excretion and urinary buffer systems are reviewed. The main focus is on the two major conditions related to acid-base metabolism that cause kidney stone formation, i.e., distal renal tubular acidosis (dRTA) and abnormally low urine pH with subsequent uric acid stone formation. Both the entities can be seen on the background of disturbances of the major urinary buffer system, NH3+ NH4+. On the one hand, reduced distal tubular secretion of H+ ions results in an abnormally high urinary pH and either incomplete or complete dRTA. On the other hand, reduced production/availability of NH4+ is the cause of an abnormally low urinary pH, which predisposes to uric acid stone formation. Most recent research indicates that the latter abnormality may be a renal manifestation of the increasingly prevalent metabolic syndrome. Despite opposite deviations from normal urinary pH values, both the dRTA and uric acid stone formation due to low urinary pH require the same treatment, i.e., alkali. In the dRTA, alkali is needed for improving the body's buffer capacity, whereas the goal of alkali treatment in uric acid stone formers is to increase the urinary pH to 6.2-6.8 in order to minimize uric acid crystallization.

  2. Current chemical concepts of acids and bases and their application to anionic ("acid") and cationic ("basic") dyes.

    Science.gov (United States)

    Puchtler, H; Meloan, S N; Spencer, M

    1985-01-01

    In biomedical studies, dyes are divided into "acid" and "basic" dyes. This classification cannot be reconciled with current chemical definitions of acids and bases. Brönsted-Lowry acids are compounds that can donate protons; bases are proton acceptors. The definition of acids and bases is independent of the electric charge, i.e. acids and bases can be neutral, anionic or cationic. Reactions between acids and bases result in formation of new acid-base pairs. Lewis acids and bases do not depend on a particular element, but are characterized by their electronic configurations. Lewis bases are electron donors; Lewis acids are electron acceptors. This classification is also unrelated to the electric charge. Lewis acids and bases interact by formation of coordinate covalent bonds. In histochemistry and histology, dyes containing -SO3-, -COO- and/or -O- groups are classified as "acid" dyes. However, such compounds are electron pair donors and hence Brönsted-Lowry and Lewis anionic bases. Dyes carrying a positive charge are termed "basic" dyes. Chemically, many cationic dyes are Lewis acids because they can add a base, e.g. OH-, acetate, halides. The hypothesis that transformation of -NH2 into ammonium groups imparts "basic" properties to dyes is untenable; ammonium groups are proton donors and hence acids. Furthermore, conversion of an amino into an ammonium group blocks a lone electron pair and the color of the dye changes drastically, e.g. from violet to green and yellow. It appears therefore highly unlikely that ammonium groups are responsible for binding of cationic ("basic") dyes. In histochemistry, it is usually not of critical importance whether anionic or cationic dyes are chemically acids or bases.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Interactions between acid- and base-functionalized surfaces

    NARCIS (Netherlands)

    Giesbers, M.; Kleijn, J.M.; Cohen Stuart, M.A.

    2002-01-01

    In this paper we present an AFM force study on interactions between chemically modified surfaces. Surfaces with terminal groups of either NH2 or COOH were obtained by chemisorption of a silane-based compound (3-amino-propyltriethoxysilane) on silica or a thiol compound (11-mercapto undecanoic acid)

  4. Students' Understanding of Acids/Bases in Organic Chemistry Contexts

    Science.gov (United States)

    Cartrette, David P.; Mayo, Provi M.

    2011-01-01

    Understanding key foundational principles is vital to learning chemistry across different contexts. One such foundational principle is the acid/base behavior of molecules. In the general chemistry sequence, the Bronsted-Lowry theory is stressed, because it lends itself well to studying equilibrium and kinetics. However, the Lewis theory of…

  5. Turkish Prospective Chemistry Teachers' Alternative Conceptions about Acids and Bases

    Science.gov (United States)

    Boz, Yezdan

    2009-01-01

    The purpose of this study was to obtain prospective chemistry teachers' conceptions about acids and bases concepts. Thirty-eight prospective chemistry teachers were the participants. Data were collected by means of an open-ended questionnaire and semi-structured interviews. Analysis of data indicated that most prospective teachers did not have…

  6. Asymmetric bipolar membranes in acid-base electrodialysis

    NARCIS (Netherlands)

    Wilhelm, Friedrich G.; Punt, Ineke; Vegt, van der Nico F.A.; Strathmann, H.; Wessling, M.

    2002-01-01

    In this experimental study, the influence of asymmetric bipolar membranes on the salt impurities in the acid and base product is investigated. The thickness of one, the other, or both ion-permeable layers of a bipolar membrane is increased. With increased layer thickness, the current-voltage curves

  7. Acid-Base Disorders--A Computer Simulation.

    Science.gov (United States)

    Maude, David L.

    1985-01-01

    Describes and lists a program for Apple Pascal Version 1.1 which investigates the behavior of the bicarbonate-carbon dioxide buffer system in acid-base disorders. Designed specifically for the preclinical medical student, the program has proven easy to use and enables students to use blood gas parameters to arrive at diagnoses. (DH)

  8. Photoresponsive self-assemblies based on fatty acids.

    Science.gov (United States)

    Fameau, A-L; Arnould, A; Lehmann, M; von Klitzing, R

    2015-02-18

    Photoresponsive surfactant system based on fatty acids has been developed by the introduction in aqueous solution of a photoacid generator (PAG). Self-assembly transitions are triggered by UV irradiation due to a pH change induced by the presence of PAG.

  9. Students' Understanding of Acids/Bases in Organic Chemistry Contexts

    Science.gov (United States)

    Cartrette, David P.; Mayo, Provi M.

    2011-01-01

    Understanding key foundational principles is vital to learning chemistry across different contexts. One such foundational principle is the acid/base behavior of molecules. In the general chemistry sequence, the Bronsted-Lowry theory is stressed, because it lends itself well to studying equilibrium and kinetics. However, the Lewis theory of…

  10. Turkish Prospective Chemistry Teachers' Alternative Conceptions about Acids and Bases

    Science.gov (United States)

    Boz, Yezdan

    2009-01-01

    The purpose of this study was to obtain prospective chemistry teachers' conceptions about acids and bases concepts. Thirty-eight prospective chemistry teachers were the participants. Data were collected by means of an open-ended questionnaire and semi-structured interviews. Analysis of data indicated that most prospective teachers did not have…

  11. A Reasoning System using Inductive Inference of Analogical Union

    OpenAIRE

    Miyahara, Tetsuhiro

    1988-01-01

    Analogical reasoning derives a new fact based on the analogous facts previously known. Inductive inference is a process of gaining a general rule from examples. We propose a new reasoning system using inductive inference and analogical reasoning. which is applicable to intellectual information processing and we characterize its power. Given an enumeration of paired examples. this system inductively infers a program representing the paring and constructs an analogical union. It reasons by anal...

  12. Plasmonics-based SERS nanobiosensor for homogeneous nucleic acid detection.

    Science.gov (United States)

    Wang, Hsin-Neng; Fales, Andrew M; Vo-Dinh, Tuan

    2015-05-01

    Developing a simple and efficient nucleic acid detection technology is essential for clinical diagnostics. Here, we describe a new conceptually simple and selective "turn on" plasmonics-based nanobiosensor, which integrates non-enzymatic DNA strand-displacement hybridization for specific nucleic acid target identification with surface-enhanced Raman scattering (SERS) detection. This SERS nanobiosensor is a target label-free, and rapid nanoparticle-based biosensing system using a homogeneous assay format that offers a simple and efficient tool for nucleic acid diagnostics. Our results showed that the nanobiosensor provided a limit of detection of ~0.1nM (200amol) in the current bioassay system, and exhibited high specificity for single nucleotide mismatch discrimination. Surface-enhanced Raman scattering (SERS) is a sensitive technique that enhances Raman scattering by molecules adsorbed on rough metal surfaces. The enhancement means that the technique may even detect single molecules. In this article, the authors describe a simple and efficient nucleic acid detection technology using SERS, with "OFF-to-ON" signal switch upon nucleic acid target identification and capture, which provides high sensitivity and specificity for single nucleotide mismatch discrimination. This new technology will be most welcomed in clinical diagnostics. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Parallel proton transfer pathways in aqueous acid-base reactions

    OpenAIRE

    Cox, M. J.; Bakker, H.J.

    2008-01-01

    We study the mechanism of proton transfer (PT) between the photoacid 8-hydroxy-1,3, 6-pyrenetrisulfonic acid (HPTS) and the base chloroacetate in aqueous solution. We investigate both proton and deuteron transfer reactions in solutions with base concentrations ranging from 0.25M to 4M. Using femtosecond midinfrared spectroscopy, we probe the vibrational responses of HPTS, its conjugate photobase, the hydrated proton/deuteron, and chloroacetate. The measurement of these four resonances allows ...

  14. Advances in Analog Circuit Design 2015

    CERN Document Server

    Baschirotto, Andrea; Harpe, Pieter

    2016-01-01

    This book is based on the 18 tutorials presented during the 24th workshop on Advances in Analog Circuit Design. Expert designers present readers with information about a variety of topics at the frontier of analog circuit design, including low-power and energy-efficient analog electronics, with specific contributions focusing on the design of efficient sensor interfaces and low-power RF systems. This book serves as a valuable reference to the state-of-the-art, for anyone involved in analog circuit research and development. ·         Provides a state-of-the-art reference in analog circuit design, written by experts from industry and academia; ·         Presents material in a tutorial-based format; ·         Includes coverage of high-performance analog-to-digital and digital to analog converters, integrated circuit design in scaled technologies, and time-domain signal processing.

  15. Model for acid-base chemistry in nanoparticle growth (MABNAG

    Directory of Open Access Journals (Sweden)

    T. Yli-Juuti

    2013-03-01

    Full Text Available Climatic effects of newly-formed atmospheric secondary aerosol particles are to a large extent determined by their condensational growth rates. However, all the vapors condensing on atmospheric nanoparticles and growing them to climatically relevant sizes are not identified yet and the effects of particle phase processes on particle growth rates are poorly known. Besides sulfuric acid, organic compounds are known to contribute significantly to atmospheric nanoparticle growth. In this study a particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth was developed to study the effect of salt formation on nanoparticle growth, which has been proposed as a potential mechanism lowering the equilibrium vapor pressures of organic compounds through dissociation in the particle phase and thus preventing their evaporation. MABNAG is a model for monodisperse aqueous particles and it couples dynamics of condensation to particle phase chemistry. Non-zero equilibrium vapor pressures, with both size and composition dependence, are considered for condensation. The model was applied for atmospherically relevant systems with sulfuric acid, one organic acid, ammonia, one amine and water in the gas phase allowed to condense on 3–20 nm particles. The effect of dissociation of the organic acid was found to be small under ambient conditions typical for a boreal forest site, but considerable for base-rich environments (gas phase concentrations of about 1010 cm−3 for the sum of the bases. The contribution of the bases to particle mass decreased as particle size increased, except at very high gas phase concentrations of the bases. The relative importance of amine versus ammonia did not change significantly as a function of particle size. While our results give a reasonable first estimate on the maximum contribution of salt formation to nanoparticle growth, further studies on, e.g. the thermodynamic properties of the atmospheric organics

  16. Acid-base thermochemistry of gaseous oxygen and sulfur substituted amino acids (Ser, Thr, Cys, Met).

    Science.gov (United States)

    Riffet, Vanessa; Frison, Gilles; Bouchoux, Guy

    2011-11-07

    Acid-base thermochemistry of isolated amino acids containing oxygen or sulfur in their side chain (serine, threonine, cysteine and methionine) have been examined by quantum chemical computations. Density functional theory (DFT) was used, with B3LYP, B97-D and M06-2X functionals using the 6-31+G(d,p) basis set for geometry optimizations and the larger 6-311++G(3df,2p) basis set for energy computations. Composite methods CBS-QB3, G3B3, G4MP2 and G4 were applied to large sets of neutral, protonated and deprotonated conformers. Conformational analysis of these species, based on chemical approach and AMOEBA force field calculations, has been used to identify the lowest energy conformers and to estimate the population of conformers expected to be present at thermal equilibrium at 298 K. It is observed that G4, G4MP2, G3B3, CBS-QB3 composite methods and M06-2X DFT lead to similar conformer energies. Thermochemical parameters have been computed using either the most stable conformers or equilibrium populations of conformers. Comparison of experimental and theoretical proton affinities and Δ(acid)H shows that the G4 method provides the better agreement with deviations of less than 1.5 kJ mol(-1). From this point of view, a set of evaluated thermochemical quantities for serine, threonine, cysteine and methionine may be proposed: PA = 912, 919, 903, 938; GB = 878, 886, 870, 899; Δ(acid)H = 1393, 1391, 1396, 1411; Δ(acid)G = 1363, 1362, 1367, 1382 kJ mol(-1). This study also confirms that a non-negligible ΔpS° is associated with protonation of methionine and that the most acidic hydrogen of cysteine in the gas phase is that of the SH group. In several instances new conformers were identified thus suggesting a re-examination of several IRMPD spectra.

  17. Enzymes for fatty acid-based hydrocarbon biosynthesis.

    Science.gov (United States)

    Herman, Nicolaus A; Zhang, Wenjun

    2016-12-01

    Surging energy consumption and environmental concerns have stimulated interest in the production of chemicals and fuels through sustainable and renewable approaches. Fatty acid-based hydrocarbons, such as alkanes and alkenes, are of particular interest to directly replace fossil fuels. Towards this effort, understanding of hydrocarbon-producing enzymes is the first indispensable step to bio-production of hydrocarbons. Here, we review recent advances in the discovery and mechanistic study of enzymes capable of converting fatty acid precursors into hydrocarbons, and provide perspectives on the future of this rapidly growing field. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Analog to Digital Conversion in Physical Measurements

    CERN Document Server

    Kapitaniak, T; Feudel, U; Grebogi, C

    1999-01-01

    There exist measuring devices where an analog input is converted into a digital output. Such converters can have a nonlinear internal dynamics. We show how measurements with such converting devices can be understood using concepts from symbolic dynamics. Our approach is based on a nonlinear one-to-one mapping between the analog input and the digital output of the device. We analyze the Bernoulli shift and the tent map which are realized in specific analog/digital converters. Furthermore, we discuss the sources of errors that are inevitable in physical realizations of such systems and suggest methods for error reduction.

  19. Digital and analog communication systems

    Science.gov (United States)

    Shanmugam, K. S.

    1979-01-01

    The book presents an introductory treatment of digital and analog communication systems with emphasis on digital systems. Attention is given to the following topics: systems and signal analysis, random signal theory, information and channel capacity, baseband data transmission, analog signal transmission, noise in analog communication systems, digital carrier modulation schemes, error control coding, and the digital transmission of analog signals.

  20. Analogical Reasoning in Geometry Education

    Science.gov (United States)

    Magdas, Ioana

    2015-01-01

    The analogical reasoning isn't used only in mathematics but also in everyday life. In this article we approach the analogical reasoning in Geometry Education. The novelty of this article is a classification of geometrical analogies by reasoning type and their exemplification. Our classification includes: analogies for understanding and setting a…

  1. Acid-base transport in pancreas – new challenges

    Directory of Open Access Journals (Sweden)

    Ivana eNovak

    2013-12-01

    Full Text Available Along the gastrointestinal tract a number of epithelia contribute with acid or basic secretions in order to aid digestive processes. The stomach and pancreas are the most extreme examples of acid (H+ and base (HCO3- transporters, respectively. Nevertheless, they share the same challenges of transporting acid and bases across epithelia and effectively regulating their intracellular pH. In this review, we will make use of comparative physiology to enlighten the cellular mechanisms of pancreatic HCO3- and fluid secretion, which is still challenging physiologists. Some of the novel transporters to consider in pancreas are the proton pumps (H+-K+-ATPases, as well as the calcium-activated K+ and Cl- channels, such as KCa3.1 and TMEM16A/ANO1. Local regulators, such as purinergic signalling, fine-tune and coordinate pancreatic secretion. Lastly, we speculate whether dys-regulation of acid-base transport contributes to pancreatic diseases including cystic fibrosis, pancreatitis and cancer.

  2. Enzymatic Polymerization of Furan-2,5-Dicarboxylic Acid-Based Furanic-Aliphatic Polyamides as Sustainable Alternatives to Polyphthalamides.

    Science.gov (United States)

    Jiang, Yi; Maniar, Dina; Woortman, Albert J J; Alberda van Ekenstein, Gert O R; Loos, Katja

    2015-11-09

    Furan-2,5-dicarboxylic acid (FDCA)-based furanic-aliphatic polyamides can be used as promising sustainable alternatives to polyphthalamides (semiaromatic polyamides) and be applied as high performance materials with great commercial interest. In this study, poly(octamethylene furanamide) (PA8F), an analog to poly(octamethylene terephthalamide) (PA8T), is successfully produced via Novozym 435 (N435)-catalyzed polymerization, using a one-stage method in toluene and a temperature-varied two-stage method in diphenyl ether, respectively. The enzymatic polymerization results in PA8F with high weight-average molecular weight (M̅(w)) up to 54000 g/mol. Studies on the one-stage enzymatic polymerization in toluene indicate that the molecular weights of PA8F increase significantly with the concentration of N435; with an optimal reaction temperature of 90 °C. The temperature-varied, two-stage enzymatic polymerization in diphenyl ether yields PA8F with higher molecular weights, as compared to the one-stage procedure, at higher reaction temperatures. MALDI-ToF MS analysis suggests that eight end groups are present in the obtained PA8F: ester/amine, ester/ester, amine/amine, acid/amine, ester/acid, acid/acid, ester/amide, and no end groups (cyclic). Compared to PA8T, the obtained PA8F possesses a similar Tg and similar crystal structures, a comparable Td, but a lower Tm.

  3. Development of a Ground-Based Analog to the Advanced Resistive Exercise Device Aboard the International Space Station

    Science.gov (United States)

    Newby, Nathaniel J.; Scott-Pandorf, M. M.; Caldwell, E.; DeWitt, J.K.; Fincke, R.; Peters, B.T.

    2010-01-01

    NASA and Wyle engineers constructed a Horizontal Exercise Fixture (HEF) that was patented in 2006. Recently modifications were made to HEF with the goal of creating a device that mimics squat exercise on the Advanced Resistive Exercise Device (ARED) and can be used by bed rest subjects who must remain supine during exercise. This project posed several engineering challenges, such as how best to reproduce the hip motions (we used a sled that allowed hip motion in the sagittal plane), how to counterweight the pelvis against gravity (we used a pulley and free-weight mechanism), and how to apply large loads (body weight plus squat load) to the shoulders while simultaneously supporting the back against gravity (we tested a standard and a safety bar that allowed movement in the subject s z-axis, both of which used a retractable plate for back support). METHODS An evaluation of the HEF was conducted with human subjects (3F, 3M), who performed sets of squat exercises of increasing load from 10-repetition maximum (RM) up to 1-RM. Three pelvic counterweight loads were tested along with each of the two back-support squat bars. Data collection included 3-dimensional ground reaction forces (GRF), muscle activation (EMG), body motion (video-based motion capture), and subjective comments. These data were compared with previous ground-based ARED study data. RESULTS All subjects in the evaluation were able to perform low- to high-loading squats on the HEF. Four of the 6 subjects preferred a pelvic counterweight equivalent to 60 percent of their body weight. Four subjects preferred the standard squat bar, whereas 2 female subjects preferred the safety bar. EMG data showed muscle activation in the legs and low back typical of squat motion. GRF trajectories and eccentric-concentric loading ratios were similar to ARED. CONCLUSION: Squat exercise performed on HEF approximated squat exercise on ARED.

  4. [Blood acid-base balance of sportsmen during physical activity].

    Science.gov (United States)

    Petrushova, O P; Mikulyak, N I

    2014-01-01

    The aim of this study was to investigate the acid-base balance parameters in blood of sportsmen by physical activity. Before exercise lactate concentration in blood was normal. Carbon dioxide pressure (рСО2), bicarbonate concentration (НСО3 -), base excess (BE), were increased immediately after physical activity lactate concentration increased, while pH, BE, НСО3 -, рСО2 decreased in capillary blood of sportsmen. These changes show the development of lactate-acidosis which is partly compensated with bicarbonate buffering system and respiratory alkalosis. During postexercise recovery lactate concentration decreased, while рСО2, НСО3 -, BE increased. The results of this study can be used for diagnostics of acid-base disorders and their medical treatment for preservation of sportsmen physical capacity.

  5. 基于果蝇优化算法的模拟滤波器设计%Design of Analog Filter Based on Fruit Fly Optimization Algorithm

    Institute of Scientific and Technical Information of China (English)

    肖正安

    2012-01-01

    基于粒子群优化算法的无源模拟滤波器优化设计方法容易陷入局部最优,收敛速度慢迭代次数多、运算量大且稳定性不够好。提出果蝇优化算法对滤波器的整个参数空间进行高效并行搜索直到获得最优的参数值,实例仿真表明,采用该方法设计的滤波器在相同的带宽准确度及阻带衰减的情况下,具有更快的运算速度及收敛性能。%The optimum design of passive simulation filters based on Particle Swarm Optimization algorithm has slow convergence velocity and may easily fall into local optimum,more iterative times,large computational complexity,and stability is not good enough.A passive analog filter optimization design method is proposed based on the Fruit Fly Optimization Algorithm(FOA),and it optimizes the circuit's parameters in the whole parameters space effectively and globally by FOA until gain the best parameters.The simulation results on the MATLAB show that our algorithm has global convergence and higher speed of optimization.

  6. Food composition and acid-base balance: alimentary alkali depletion and acid load in herbivores.

    Science.gov (United States)

    Kiwull-Schöne, Heidrun; Kiwull, Peter; Manz, Friedrich; Kalhoff, Hermann

    2008-02-01

    Alkali-enriched diets are recommended for humans to diminish the net acid load of their usual diet. In contrast, herbivores have to deal with a high dietary alkali impact on acid-base balance. Here we explore the role of nutritional alkali in experimentally induced chronic metabolic acidosis. Data were collected from healthy male adult rabbits kept in metabolism cages to obtain 24-h urine and arterial blood samples. Randomized groups consumed rabbit diets ad libitum, providing sufficient energy but variable alkali load. One subgroup (n = 10) received high-alkali food and approximately 15 mEq/kg ammonium chloride (NH4Cl) with its drinking water for 5 d. Another group (n = 14) was fed low-alkali food for 5 d and given approximately 4 mEq/kg NH4Cl daily for the last 2 d. The wide range of alimentary acid-base load was significantly reflected by renal base excretion, but normal acid-base conditions were maintained in the arterial blood. In rabbits fed a high-alkali diet, the excreted alkaline urine (pH(u) > 8.0) typically contained a large amount of precipitated carbonate, whereas in rabbits fed a low-alkali diet, both pH(u) and precipitate decreased considerably. During high-alkali feeding, application of NH4Cl likewise decreased pH(u), but arterial pH was still maintained with no indication of metabolic acidosis. During low-alkali feeding, a comparably small amount of added NH4Cl further lowered pH(u) and was accompanied by a significant systemic metabolic acidosis. We conclude that exhausted renal base-saving function by dietary alkali depletion is a prerequisite for growing susceptibility to NH4Cl-induced chronic metabolic acidosis in the herbivore rabbit.

  7. Playing with a double-edged sword: Analogies in biochemistry

    Science.gov (United States)

    Orgill, Marykay

    Analogy pervades our everyday reasoning. No situation we encounter is exactly like a situation we have encountered previously, and our ability to learn and survive in the world is based on our ability to find similarities between past and present situations and use the knowledge we have gained from past situations to manage current situations. Analogies can be powerful teaching tools because they can make new material intelligible to students by comparing it to material that is already familiar. It is clear, though, that not all analogies are good and that not all good analogies are useful to all students. In this study, I have used textbook analysis, classroom observations, student interviews and instructor interviews to determine the role that analogies play in biochemistry learning. Analogies are an important teaching technique in biochemistry classes, being used more often in both biochemistry classes and textbooks than they are in high school chemistry classes and textbooks. Most biochemistry students like, pay particular attention to, and remember the analogies their instructors provide; and they use these analogies to understand, visualize, and recall information from class. Even though students like and use analogies, they do not understand what analogies are or the mechanism by which they improve learning. For the students, analogies are simply any teaching technique that eases understanding, visualization, or recall. Instructors, on the other hand, have a good understanding of what analogies are and of how they should be presented in class; but they do not use analogies as effectively as they should. They do not plan, explain or identify the limitations of the analogies they use in class. However, regardless of how effectively instructors present analogies in class, this study indicates that, in general, analogies are useful in promoting understanding, visualization, recall, and motivation in biochemistry students at all levels. They would be even more

  8. Final Project Report for project titled "Fluoroalkylphosphonic-acid-based proton conductors"

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Creager

    2011-12-08

    The overall objective of this research was to create new proton-conducting polymer electrolytes for use in energy conversion devices including hydrogen fuel cells that could operate at high temperatures (95-130 C) and under low relative humidity (< 50% RH) conditions. The new polymers were based on the fluoroalkylphosphonic and phosphinic acid (FPA) groups (see illustration below) which offer prospects for rapid proton transport by a proton-hopping mechanism similar to that which operates in phosphoric acid, a well-known proton-transporting electrolyte that is used in a class of hydrogen fuel cells that work well under the conditions noted above and are already commercially successful. The two specific project objectives were as follows: (1) synthesize and characterize new proton-conducting electrolytes based on the fluoroalkylphosphonic and phosphinic acid (FPA) functional groups; and (2) create and apply new computer models to study protonic conduction in FPA-based electrolytes. The project was successful in creating the desired polymer electrolytes and also a series of molecular model compounds which were used to study proton transport in FPA electrolytes in general. Computer models were created to study both structure and proton-transport dynamics in the electrolytes, particularly the molecular model compounds. Rapid proton transport by a hopping mechanism was found in many of the model compounds and correlations with transport rates with molecular structure were identified. Several polymeric analogs of FPA model compounds were prepared and studied, however FPA-based polymeric materials having very high protonic conductivities under either wet or dry conditions were not obtained. Several possible reasons for the failure of polymeric materials to exhibit the expected high protonic conductivities were identified, including a failure of the polymers to adopt the phase-separated secondary structure/morphology necessary for high proton conductivity, and an

  9. Hard and soft acids and bases: structure and process.

    Science.gov (United States)

    Reed, James L

    2012-07-05

    Under investigation is the structure and process that gives rise to hard-soft behavior in simple anionic atomic bases. That for simple atomic bases the chemical hardness is expected to be the only extrinsic component of acid-base strength, has been substantiated in the current study. A thermochemically based operational scale of chemical hardness was used to identify the structure within anionic atomic bases that is responsible for chemical hardness. The base's responding electrons have been identified as the structure, and the relaxation that occurs during charge transfer has been identified as the process giving rise to hard-soft behavior. This is in contrast the commonly accepted explanations that attribute hard-soft behavior to varying degrees of electrostatic and covalent contributions to the acid-base interaction. The ability of the atomic ion's responding electrons to cause hard-soft behavior has been assessed by examining the correlation of the estimated relaxation energies of the responding electrons with the operational chemical hardness. It has been demonstrated that the responding electrons are able to give rise to hard-soft behavior in simple anionic bases.

  10. Model for acid-base chemistry in nanoparticle growth (MABNAG)

    Science.gov (United States)

    Yli-Juuti, T.; Barsanti, K.; Hildebrandt Ruiz, L.; Kieloaho, A.-J.; Makkonen, U.; Petäjä, T.; Ruuskanen, T.; Kulmala, M.; Riipinen, I.

    2013-12-01

    Climatic effects of newly-formed atmospheric secondary aerosol particles are to a large extent determined by their condensational growth rates. However, all the vapours condensing on atmospheric nanoparticles and growing them to climatically relevant sizes are not identified yet and the effects of particle phase processes on particle growth rates are poorly known. Besides sulfuric acid, organic compounds are known to contribute significantly to atmospheric nanoparticle growth. In this study a particle growth model MABNAG (Model for Acid-Base chemistry in NAnoparticle Growth) was developed to study the effect of salt formation on nanoparticle growth, which has been proposed as a potential mechanism lowering the equilibrium vapour pressures of organic compounds through dissociation in the particle phase and thus preventing their evaporation. MABNAG is a model for monodisperse aqueous particles and it couples dynamics of condensation to particle phase chemistry. Non-zero equilibrium vapour pressures, with both size and composition dependence, are considered for condensation. The model was applied for atmospherically relevant systems with sulfuric acid, one organic acid, ammonia, one amine and water in the gas phase allowed to condense on 3-20 nm particles. The effect of dissociation of the organic acid was found to be small under ambient conditions typical for a boreal forest site, but considerable for base-rich environments (gas phase concentrations of about 1010 cm-3 for the sum of the bases). The contribution of the bases to particle mass decreased as particle size increased, except at very high gas phase concentrations of the bases. The relative importance of amine versus ammonia did not change significantly as a function of particle size. While our results give a reasonable first estimate on the maximum contribution of salt formation to nanoparticle growth, further studies on, e.g. the thermodynamic properties of the atmospheric organics, concentrations of low

  11. Amino acid substitutions in HIV-1 reverse transcriptase with corresponding residues from HIV-2. Effect on kinetic constants and inhibition by non-nucleoside analogs.

    Science.gov (United States)

    Bacolla, A; Shih, C K; Rose, J M; Piras, G; Warren, T C; Grygon, C A; Ingraham, R H; Cousins, R C; Greenwood, D J; Richman, D

    1993-08-05

    Nevirapine is a highly potent and specific inhibitor of human immunodeficiency virus type 1 (HIV-1) polymerase, but is inactive against HIV-2 and other polymerase. Previous studies demonstrated that residues 176-190 of HIV-1 reverse transcriptase (RT) can confer nevirapine sensitivity to HIV-2 RT. To better characterize the role of this sequence in HIV-1 RT, we have progressively substituted residues 176-190 of HIV-2 RT for those of HIV-1 RT and monitored the impact on the kinetic properties; inhibitory activity of nevirapine (11-cyclopropyl-5,11-dihydro-4-methyl-6H-dipyrido[2,3-b:2',3'-e] [1,4]diazepin-6-one), E-BPU (5-ethyl-1-benzyloxymethyl-6-(phenylthio)-uracil), and TIBO-R82150 ((+)-S-4,5,6,7-tetrahydro-5-methyl-6-(3-methyl-2-butenyl)imidazo[4,5,1-j k] [1,4]benzodiazepin-2(1H)-thione); and inhibitor-induced fluorescence changes of the mutant enzymes. The study revealed that in addition to Try-181 and Tyr-188, a new amino acid residue (Gly-190) plays an important role in determining susceptibility to nevirapine and E-BPU, but not to TIBO-R82150. These data argue that these non-nucleoside inhibitors fit differently, even though they share a common binding pocket. Nevirapine was seen to exert inhibitory activity by altering the interaction of the enzyme with the template-primer. Kinetic parameters were modulated by the template (DNA versus RNA) as well as by some of the mutations.

  12. Synthetic heparin-binding factor analogs

    Science.gov (United States)

    Pena, Louis A.; Zamora, Paul O.; Lin, Xinhua; Glass, John D.

    2010-04-20

    The invention provides synthetic heparin-binding growth factor analogs having at least one peptide chain, and preferably two peptide chains branched from a dipeptide branch moiety composed of two trifunctional amino acid residues, which peptide chain or chains bind a heparin-binding growth factor receptor and are covalently bound to a non-signaling peptide that includes a heparin-binding domain, preferably by a linker, which may be a hydrophobic linker. The synthetic heparin-binding growth factor analogs are useful as pharmaceutical agents, soluble biologics or as surface coatings for medical devices.

  13. Analogical Learning and Automated Rule Constructions

    Institute of Scientific and Technical Information of China (English)

    周哈阳

    1991-01-01

    This paper describes some experiments of analogical learning and automated rule construction.The present investigation focuses on knowledge acquisition,learning by analyogy,and knowledge retention.The developed system initially learns from scratch,gradually acquires knowledge from its environment through trial-and-error interaction,incrementally augments its knowledge base,and analogically solves new tasks in a more efficient and direct manner.

  14. Automated Integrated Analog Filter Design Issues

    OpenAIRE

    2015-01-01

    An analysis of modern automated integrated analog circuits design methods and their use in integrated filter design is done. Current modern analog circuits automated tools are based on optimization algorithms and/or new circuit generation methods. Most automated integrated filter design methods are only suited to gmC and switched current filter topologies. Here, an algorithm for an active RC integrated filter design is proposed, that can be used in automated filter designs. The algorithm is t...

  15. Protein Structure Prediction with Visuospatial Analogy

    Science.gov (United States)

    Davies, Jim; Glasgow, Janice; Kuo, Tony

    We show that visuospatial representations and reasoning techniques can be used as a similarity metric for analogical protein structure prediction. Our system retrieves pairs of α-helices based on contact map similarity, then transfers and adapts the structure information to an unknown helix pair, showing that similar protein contact maps predict similar 3D protein structure. The success of this method provides support for the notion that changing representations can enable similarity metrics in analogy.

  16. Bio-based production of organic acids with Corynebacterium glutamicum.

    Science.gov (United States)

    Wieschalka, Stefan; Blombach, Bastian; Bott, Michael; Eikmanns, Bernhard J

    2013-03-01

    The shortage of oil resources, the steadily rising oil prices and the impact of its use on the environment evokes an increasing political, industrial and technical interest for development of safe and efficient processes for the production of chemicals from renewable biomass. Thus, microbial fermentation of renewable feedstocks found its way in white biotechnology, complementing more and more traditional crude oil-based chemical processes. Rational strain design of appropriate microorganisms has become possible due to steadily increasing knowledge on metabolism and pathway regulation of industrially relevant organisms and, aside from process engineering and optimization, has an outstanding impact on improving the performance of such hosts. Corynebacterium glutamicum is well known as workhorse for the industrial production of numerous amino acids. However, recent studies also explored the usefulness of this organism for the production of several organic acids and great efforts have been made for improvement of the performance. This review summarizes the current knowledge and recent achievements on metabolic engineering approaches to tailor C. glutamicum for the bio-based production of organic acids. We focus here on the fermentative production of pyruvate, L- and D-lactate, 2-ketoisovalerate, 2-ketoglutarate, and succinate. These organic acids represent a class of compounds with manifold application ranges, e.g. in pharmaceutical and cosmetics industry, as food additives, and economically very interesting, as precursors for a variety of bulk chemicals and commercially important polymers.

  17. The Neoarchaean surficial sulphur cycle: An alternative hypothesis based on analogies with 20th-century atmospheric lead.

    Science.gov (United States)

    Gallagher, M; Whitehouse, M J; Kamber, B S

    2017-05-01

    We revisit the S-isotope systematics of sedimentary pyrite in a shaly limestone from the ca. 2.52 Ga Gamohaan Formation, Upper Campbellrand Subgroup, Transvaal, South Africa. The analysed rock is interpreted to have been deposited in a water depth of ca. 50-100 m, in a restricted sub-basin on a drowning platform. A previous study discovered that the pyrites define a nonzero intercept δ(34) SV-CDT -Δ(33) S data array. The present study carried out further quadruple S-isotope analyses of pyrite, confirming and expanding the linear δ(34) SV-CDT -Δ(33) S array with an δ(34) S zero intercept at ∆(33) S ca. +5. This was previously interpreted to indicate mixing of unrelated S-sources in the sediment environment, involving a combination of recycled sulphur from sulphides that had originally formed by sulphate-reducing bacteria, along with elemental sulphur. Here, we advance an alternative explanation based on the recognition that the Archaean seawater sulphate concentration was likely very low, implying that the Archaean ocean could have been poorly mixed with respect to sulphur. Thus, modern oceanic sulphur systematics provide limited insight into the Archaean sulphur cycle. Instead, we propose that the 20th-century atmospheric lead event may be a useful analogue. Similar to industrial lead, the main oceanic input of Archaean sulphur was through atmospheric raindown, with individual giant point sources capable of temporally dominating atmospheric input. Local atmospheric S-isotope signals, of no global significance, could thus have been transmitted into the localised sediment record. Thus, the nonzero intercept δ(34) SV-CDT -Δ(33) S data array may alternatively represent a very localised S-isotope signature in the Neoarchaean surface environment. Fallout from local volcanic eruptions could imprint recycled MIF-S signals into pyrite of restricted depositional environments, thereby avoiding attenuation of the signal in the subdued, averaged global open ocean

  18. Acid-base properties of Baltic Sea dissolved organic matter

    Science.gov (United States)

    Hammer, Karoline; Schneider, Bernd; Kuliński, Karol; Schulz-Bull, Detlef E.

    2017-09-01

    Calculations related to the marine CO2 system that are based on alkalinity data may be strongly biased if the contributions of organic compounds are ignored. In coastal seas, concentrations of dissolved organic matter (DOM) are frequently high and alkalinity from inorganic compounds is low. In this study, based on measurements of total alkalinity, total CO2, and pH, we determined the organic alkalinity, Aorg, in water from the central Baltic Sea. The maximum Aorg measured in the surface mixed layer during the spring bloom was > 50 μmol/kg-SW but the Aorg decreased with depth and approached zero below the permanent halocline. This behavior could be attributed to the decreased pH of deeper water layers. The data were used to calculate the bulk dissociation constant, KDOM, for marine DOM and the fraction f of dissolved organic carbon (DOC) that acts as a carrier for acid-base functional groups. The p KDOM (7.27) agreed well with the value (7.34) previously estimated in a preliminary study of organic alkalinity in the Baltic Sea. The fraction of carbon atoms carrying acid-base groups was 17% and was somewhat higher than previously reported (12%). Spike experiments performed using artificial seawater and three different humic/fulvic substances tested whether the acid-base properties of these substances explain the results of our field study. Specifically, Aorg was determined at different concentrations (DOC) of the added humic/fulvic substances. The relationship between Aorg and the DOC concentrations indicated that humic/fulvic substances are more acidic (p KDOM < 6.5) than the bulk DOC natural occurring in the Baltic Sea.

  19. Developing nucleic acid-based electrical detection systems

    Directory of Open Access Journals (Sweden)

    Gabig-Ciminska Magdalena

    2006-03-01

    Full Text Available Abstract Development of nucleic acid-based detection systems is the main focus of many research groups and high technology companies. The enormous work done in this field is particularly due to the broad versatility and variety of these sensing devices. From optical to electrical systems, from label-dependent to label-free approaches, from single to multi-analyte and array formats, this wide range of possibilities makes the research field very diversified and competitive. New challenges and requirements for an ideal detector suitable for nucleic acid analysis include high sensitivity and high specificity protocol that can be completed in a relatively short time offering at the same time low detection limit. Moreover, systems that can be miniaturized and automated present a significant advantage over conventional technology, especially if detection is needed in the field. Electrical system technology for nucleic acid-based detection is an enabling mode for making miniaturized to micro- and nanometer scale bio-monitoring devices via the fusion of modern micro- and nanofabrication technology and molecular biotechnology. The electrical biosensors that rely on the conversion of the Watson-Crick base-pair recognition event into a useful electrical signal are advancing rapidly, and recently are receiving much attention as a valuable tool for microbial pathogen detection. Pathogens may pose a serious threat to humans, animal and plants, thus their detection and analysis is a significant element of public health. Although different conventional methods for detection of pathogenic microorganisms and their toxins exist and are currently being applied, improvements of molecular-based detection methodologies have changed these traditional detection techniques and introduced a new era of rapid, miniaturized and automated electrical chip detection technologies into pathogen identification sector. In this review some developments and current directions in

  20. Are Scientific Analogies Metaphors?

    Science.gov (United States)

    1981-02-01

    psychospiritual processes. A more modern example of unclarified analogy is Freud’s (1973; reprinted from 1955) discussion of anal- eroticism , in which...299-304. Freud, S. On transformations of instinct as exemplified in anal eroticism . In J. Strachey (Ed.), The standard 37 edition of the complete