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"Mack, John"
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The sea : a cultural history
Explores the diversity of the seas themselves, maritime technologies, especially the practice of navigation, and different cultures surrounding the sea.
Book
Molecular and cellular basis of acid taste sensation in Drosophila
Acid taste, evoked mainly by protons (H
+
), is a core taste modality for many organisms. The hedonic valence of acid taste is bidirectional: animals prefer slightly but avoid highly acidic foods. However, how animals discriminate low from high acidity remains poorly understood. To explore the taste perception of acid, we use the fruit fly as a model organism. We find that flies employ two competing taste sensory pathways to detect low and high acidity, and the relative degree of activation of each determines either attractive or aversive responses. Moreover, we establish one member of the fly Otopetrin family, Otopetrin-like a (OtopLa), as a proton channel dedicated to the gustatory detection of acid. OtopLa defines a unique subset of gustatory receptor neurons and is selectively required for attractive rather than aversive taste responses. Loss of
otopla
causes flies to reject normally attractive low-acid foods. Therefore, the identification of OtopLa as a low-acid sensor firmly supports our competition model of acid taste sensation. Altogether, we have discovered a binary acid-sensing mechanism that may be evolutionarily conserved between insects and mammals.
Many animals, including mammals and insects, like slightly acidic yet dislike highly acidic foods, but how animals discriminate low from high acidity is unclear. Here the authors demonstrate that the fruit fly uses an evolutionarily conserved taste receptor to distinguish low from high concentrations of acid.
Journal Article
Mathematics and its teaching in the Asia-Pacific region
\"This book provides the global mathematics education community with information on the recent and current status of the teaching of mathematics in a group of island nations in the Asia-Pacific region. Sri Lanka, Indonesia, Japan, the Philippines, Australia, Papua New Guinea, New Zealand, and twelve nations in the South Pacific Ocean. It is the third volume in a series conceived by Dr Bruce Vogeli of Columbia University Teachers College and published by WSP, aimed at producing contemporary accounts of mathematics teaching in a world-wide group of nations. Previous volumes have covered Central and South American nations and a selection of Muslim nations respectively\"-- Provided by publisher.
Book
Corrosion Resistance of Aluminum against Acid Activation: Impact of Benzothiazole-Substituted Gallium Phthalocyanine
This study describes the adsorption behavior of organic inhibitors at the aluminum-HCl solution interface and their corrosion inhibition performance. The organic inhibitors employed are: 4-(benzo [d]thiazol-2ylthio)phthalonitrile (BTThio) and tetrakis[(benzo[d]thiazol-2-yl-thio)phthalo- cyaninato]gallium(III) chloride (ClGaBTThioPc). The corrosion behavior of these inhibitors is investigated using electrochemical and computational techniques. Open circuit potential results reveal predominant cathodic character for the mechanism of aluminum corrosion inhibition by the inhibitors. Inhibition efficiency values from potentiodynamic polarization measurements increase from 46.9 to 70.8% for BTThio and 59.7 to 81.0% for ClGaBTThioPc within the concentration range of 2 to 10 μM. Scanning electron microscopy (SEM) measurements reveal protection of the metal surface from acid attack, in the presence of the inhibitors and energy dispersive X-ray (EDX) measurements show that the most probable way by which the inhibitors protect the metal surface would be by shielding it from the corrosion attacks of Cl− from the acid. Quantum chemical parameters corroborate well with experimental findings.
Journal Article
The Photodynamic Anticancer and Antibacterial Activity Properties of a Series of meso-Tetraarylchlorin Dyes and Their Sn(IV) Complexes
A series of tetraarylchlorins with 3-methoxy-, 4-hydroxy- and 3-methoxy-4-hydroxyphenyl meso-aryl rings (1-3-Chl) and their Sn(IV) complexes (1-3-SnChl) were synthesized and characterized so that their potential utility as photosensitizer dyes for use in photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) can be assessed. The photophysicochemical properties of the dyes were assessed prior to in vitro PDT activity studies against MCF-7 breast cancer cells through irradiation with Thorlabs 625 or 660 nm LED for 20 min (240 or 280 mW·cm−2). PACT activity studies were performed against both planktonic bacteria and biofilms of Gram-(+) S. aureus and Gram-(−) E. coli upon irradiation with Thorlabs 625 and 660 nm LEDs for 75 min. The heavy atom effect of the Sn(IV) ion results in relatively high singlet oxygen quantum yield values of 0.69−0.71 for 1-3-SnChl. Relatively low IC50 values between 1.1−4.1 and 3.8−9.4 µM were obtained for the 1-3-SnChl series with the Thorlabs 660 and 625 nm LEDs, respectively, during the PDT activity studies. 1-3-SnChl were also found to exhibit significant PACT activity against planktonic S. aureus and E. coli with Log10 reduction values of 7.65 and >3.0, respectively. The results demonstrate that the Sn(IV) complexes of tetraarylchlorins merit further in depth study as photosensitizers in biomedical applications.
Journal Article
The American West : a new interpretive history
The newly revised second edition of this concise, engaging, and unorthodox history of America's West has been updated to incorporate new research, including recent scholarship on Native American lives and cultures. An ideal text for course work, it presents the West as both frontier and region, examining the clashing of different cultures and ethnic groups that occurred in the western territories from the first Columbian contacts between Native Americans and Europeans up to the end of the twentieth century.
Book
NIR Absorbing AzaBODIPY Dyes for pH Sensing
Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes 2a and 2b were synthesized and characterized that differ depending on whether the dimethylaniline substituents are introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH2Cl2. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH2Cl2, and a fluorescence “turn-on” effect in the NIR region. The pH dependence studies reveal that the pKa values of the non-protonated 2a and 2b molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.
Journal Article
Circular dichroism and magnetic circular dichroism spectroscopy for organic chemists
CD and MCD spectroscopy can provide key information about the conformations and electronic states of chromophore containing molecules. However, the theory has remained too challenging and inaccessible for many organic chemists and biochemists and only a few researchers have carried out detailed quantitative analyses of their spectral data. This is not surprising as people who excel at spectroscopic theory usually lack the skills set required to design and synthesise the molecules that would be most appropriate for describing and explaining the theory of CD and MCD spectroscopy. Most of the books that have been written on the subject have, therefore, been based on very dense sets of mathematical equations. This timely book rectifies that situation by summarizing the relationship between the different types of spectra and by describing in detail the qualitative and quantitative methods which can readily be used to analyse CD and MCD spectral data. During the last decade the authors have successfully synthesized several molecules to illustrate key points related to the theory of CD and MCD spectroscopy, resulting in this definitive book providing key practical knowledge in a readily accessible style. It is aimed primarily at organic chemists and biochemists and is required reading for researchers active in the field. In the introduction, the book describes the types of information that can be derived from CD and MCD spectroscopy. After a detailed explanation of the theory of electronic absorption spectroscopy, it then provides practical in depth examples of the various analytical methods that can be carried out with CD and MCD spectral data. This makes the theory of these techniques much more accessible for researchers who do not specialise in physical chemistry. The book concludes by briefly summarizing the key mathematical expressions associated with each technique.
eBook
Low-Symmetry Phthalocyanines Bearing Carboxy-Groups: Synthesis, Spectroscopic and Quantum-Chemical Characterization
The synthesis and characterization of A3B-type phthalocyanines, ZnPc1–4, bearing bulky 2,6-diisopropylphenoxy-groups or chlorine atoms on isoindoline units “A” and either one or two carboxylic anchors on isoindoline unit “B” are reported. A comparison of molecular modelling with the conventional time dependent—density functional theory (TD-DFT) approach and its simplified sTD-DFT approximation provides further evidence that the latter method accurately reproduces the key trends in the spectral properties, providing colossal savings in computer time for quite large molecules. This demonstrates that it is a valuable tool for guiding the rational design of new phthalocyanines for practical applications.
Journal Article