DOCSLIB.ORG

Universität Bonn Physikalisches Institut

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Universität Bonn Physikalisches Institut DE13F7563 Universität Bonn Physikalisches Institut X-Ray Absorption Spectroscopy in Biological Systems: Opportunities and Limitations von Gudrun Lisa Bovenkamp X-ray absorption spectroscopy has become more important for applications in the material sciences, geology, environmental science and biology, specifically in the field of molecular biology. The scope of this thesis is to add more experimental evidence in order to show how applicable X-ray absorption near edge structure (XANES) is to biology. Two biological systems were investigated, at the molecular level, lead uptake in plants and the effect of silver on bacteria. This investigation also included an analysis of the sensitivity of Pb L3- and Ag L3-XANES spectra with regard to their chemical environment. It was shown that Pb L3- and Ag L3 -XANES spectra are sensitive to an environment with at least differences in the second coordination shell. The non-destructive and element specific properties of XANES are the key advantages that were very important for this investigation. However, in both projects the adequate selection of reference compounds, which required in some cases a chemical synthesis, was the critical factor to determine the chemical speciation and, finally, possible uptake and storage mechanisms for plants and antibacterial mechanisms of silver. The chemical environment of Pb in roots and leaves of plants from four different plant families and a lichen from a former lead mining site in the Eifel mountains in Germany was determined using both solid compounds and aqueous solutions of different ionic strength, which simulate the plant environment. The results can be interpreted in such a way that lead is sorbed on the surface of cell walls. Silver bonding as reaction with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli bacteria was determined using inorganic silver compounds and synthesized silver amino acids. Silver binds to sulfur, amine and carboxyl groups in amino acids. Post address: BONN-IR-2013-07 Nussallee 12 Bonn University 53115 Bonn Mai 2013 Germany ISSN 0172-8741 Universität Bonn Physikalisches Institut X-Ray Absorption Spectroscopy in Biological Systems: Opportunities and Limitations von Gudrun Lisa Bovenkamp aus Dinslaken Dieser Forschungsbericht wurde als Dissertation von der Mathematisch-Naturwissenschaftlichen Fakultät der Universität Bonn angenommen. Angenommen am: 24.5.2013 1. Gutachter: Prof. Dr. Josef Hormes 2. Gutachter: Prof. Dr. Karl Maier Dedicated to my parents, Brigitte Bovenkamp and Armin Bovenkamp Acknowledgements Primarily, I would like to express my deepest gratitude to Prof. Dr. Josef Hormes, my advisor. He gave me this once in a life time chance of becoming a doctor of physics and spending major parts of my PhD time at CAMD, Baton Rouge, LA. It is so much fan to work with him! I am very grateful for all the interesting discussions we had, his patience, his support, and his guidance. I would like to thank Prof. Dr. Karl Maier and Prof. Dr. Marcel Drees for their participation in my PhD committee. I am very grateful to Prof. Dr. Dr. Alexander Prange, our expert in microbiology, for being the fourth member of my PhD committee, for the exciting discussions, and the invaluable experience of working together. I would like to thank the (previous and current) members of the Bonn Synchrotron Radiation (Syli) group: Hubert Blank, Dr. Timna-Joshua Kühn, Martin Niestroj, Mathias Fischer, and Dr. Henning Lichtenberg for their friendship and the discussions over long distances. I would like to thank the members of the INE beamline at ANKA, Dr. Melissa Denecke, Dr. Kathy Dardenne, Dr. Tonya Vitova, Dr. Boris Brendebach, Dr. Jörg Rothe; Dr. Stefan Mangold from the XAS beamline, and Dr. Jörg Göttlicher and Dr. Ralf Steininger from the SUL-X beamline at ANKA; for their great support at all times and the great atmosphere. I would like to thank Dr. Challa Kumar and Dr. Sai Krishna Katla for their discussions and help with the syntheses of the additional compounds and chemical experiments. I am very grateful for the patience and help of Dr. Joshua J. Kas from the FEFF team during our long discussions on the theory of XAS and FEFF calculations. I would like to thank the CAMD family for welcoming me as part of the family, especially Craig Stevens and Dr. John Scott. I would like to thank Dr. Amitava Roy, Dr. Kyungmin Ham, and Gregory Merchan from the X-ray group at CAMD. It is a pleasure working with you! I would like to express my gratitude to Rose and Dr. John Howe for their invaluable help with editing and correcting. Finally, I would like to thank my family and my friends for their love and their unwavering support, especially Brigitte Bovenkamp and John D. Langlois. Contents Chapter 1 - Introduction 1 Chapter 2 - XAS - Theory and Experiment 5 2.1 The Physics of X-ray Absorption Spectroscopy............................................................................ 5 2.1.1 Basics of XAS.......................................................................................................................... 5 2.1.2 XA N ES................................................................................................................................... 6 2.2 Theoretical Aspects of XAS and the FEFF9 c o d e .......................................................................... 7 2.3 Synchrotron Radiation .................................................................................................................. 11 2.4 The XAS experiment....................................................................................................................... 12 2.4.1 Experimental setup and Instrumentation.......................................................................... 12 2.4.2 Data an alysis....................................................................................................................... 15 2.5 Materials and Sample Preparation .............................................................................................. 17 2.5.1 Powder materials and solution experiments for Pb experiments .................................... 17 2.5.2 Powder materials and solution experiments for Ag experim ents.................................... 17 2.5.3 Plant preparation ................................................................................................................ 18 2.5.4 Bacterial strains, media and cultivation ............................................................................ 18 2.6 Other experimental methods . ...................................................................................................... 19 2.6.1 ICP-AES and AAS analysis ................................................................................................... 19 2.6.2 X-ray Tomography experiment and param eters................................................................ 20 2.6.3 XRF experiments .................................................................................................................. 20 2.6.4 XRD experiments.................................................................................................................. 20 2.6.5 FTIR experiments.................................................................................................................. 20 Chapter 3 - Lead uptake in plants 21 3.1 Sensitivity of XANES spectra regarding the chemical environment............................................ 24 3.1.1 Determination of the limit of uncertainty for the sensitivity analysis of XANES spectra .. 25 3.1.2 Determination of the level of sensitivity of XANES spectra................................................ 28 3.1.3 Sensitivity analysis of Pb L3-edge XANES spectra............................................................... 30 3.1.4 Sensitivity analysis of Pb Lr edge XANES spectra............................................................... 32 3.1.5 Sensitivity analysis of Pb M5-edge XANES spectra ............................................................. 33 3.2 Quantitative Analysis using linear combination fittin g ................................................................ 36 3.3 Simulating the biological environment - adequate reference compounds................................. 40 3.3.1 Biological functional groups................................................................................................ 40 3.3.2 Lead in solutions.................................................................................................................. 41 3.4 The uptake of lead in plants........................................................................................................... 43 3.4.1 Pb L3-XANES measurements .............................................................................................. 43 3.4.2 Other techniques................................................................................................................... 50 3.5 FEFF Simulations at Pb L3-edge...................................................................................................... 53 3.5.1 DOS calculations for Pb compounds.................................................................................... 54 i 3.5.2 Simulation of the plant model.............................................................................................. 56 Chapter 4 - Silver speciation in bacteria 59 4.1 Sensitivity of Ag L3-XANES spectra regarding the chemical environment................................... 60 4.1.1 Determination of the
Load more

Recommended publications
  • Perchloric Acid and Some Organic Perchlorates”
    View Article Online / Journal Homepage / Table of Contents for this issue 4 BURTON AND PRAILL: PERCHLORIC ACID [Vol. 80 Perchloric Acid and Some Organic Perchlorates” BY H. BURTON AND P. F. G. PRAILL (Presented at the W’ngof the Society on Wednesday,July 21st, 1954) The history crf perchlorates is summarised and various methods of pre- paration of the acid are noted. The action of perchloric acid and some organic perchlorates on various types of organic compounds, e.g., anhydrides and ethers, is discussed with particular reference to the formation of, especially, the alkyl perchlorates and related compounds. The simple alkyl esters of Published on 01 January 1955. Downloaded by University of Reading 29/10/2017 13:59:35. perchloric acid have long been known to be highly explosive; in the free state they possess many of the properties of covalent compounds. Con- sequently, when experiments that can lead to their formation are carried out, the risk of serious explosion is always present. GROWINGinterest in the applications of perchloric acid to analytical chemistry makes the recognition of its properties imperative. Perchloric acid and the perchlorates have a notorious reputation; this is due to numerous explosions that have been recorded (Hackl’; Meyer and Spormann2; Kahane3; Zahn4; Balks and Wehrrnann5; Young and Campbell6; and others to be mentioned later) and also to the lack of extensive investigations of their properties. Whilst it is not intended that the hazardous properties of perchloric acid should be belittled, it is thought that a better understanding of its character may dispel some of the fears that have * Much of the chemistry of perchloric acid and perchlorates is summarised in “The Chemical Elements and Their Compounds,” by N.
    [Show full text]
  • A Novel Route to Synthesis of Lead Glycolate and Perovskite Lead Titanate, Lead Zirconate, and Lead Zirconate Titanate (PZT)
    36 «“√ “√«‘®—¬ ¡¢. (∫».) 7 (1) : ¡.§. - ¡’.§. 2550 A Novel Route to Synthesis of Lead Glycolate and Perovskite Lead Titanate, Lead Zirconate, and Lead Zirconate Titanate (PZT) via Sol-Gel Process π«—µ°√√¡¢Õß°√–∫«π°“√ —߇§√“–Àå‡≈¥‰°≈‚§‡≈µ·≈–‚§√ß √â“ß·∫∫ ‡æÕ√Õø ‰°µå¢Õ߇≈¥‰∑∑“‡πµ ‡≈¥‡´Õ√傧‡πµ ·≈– ‡≈¥‡´Õ√傧‡πµ‰∑∑“‡πµ ºà“π°√–∫«π°“√‚´≈-‡®≈ Nuchnapa Tangboriboon (πÿ™π¿“ µ—Èß∫√‘∫Ÿ√≥å)* Dr. Sujitra Wongkasemjit (¥√. ÿ®‘µ√“ «ß»å‡°…¡®‘µµå)** Dr. Alexander M. Jameison (¥√. Õ‡≈Á°´“π‡¥Õ√å ‡ÕÁ¡ ‡®¡‘ —π)*** Dr. Anuvat Sirivat (¥√. Õπÿ«—≤πå »‘√‘«—≤πå)**** ABSTRACT The reaction of lead acetate trihydrate Pb(CH3COO)2.3H2O and ethylene glycol, using triethylenetetramine (TETA) as a catalyst, provides, in one step, an access to a polymer-like precursor of lead glycolate [-PbOCH2CH2O-] via oxide one pot synthesis (OOPS). The lead glycolate precursor has superior electrical properties than lead acetate trihydrate, suggesting that the lead glycolate precursor can possibly be used as a starting material mixed with other precursors such as titanium glycolate and sodium tris (glycozirconate) to produce lead titanate, lead zirconate, and lead zirconate titanate by sol-gel transition process. ∫∑§¥¬— àÕ ß“π«‘®—¬π’ȉ¥â»÷°…“°“√‡°‘¥ªØ‘°‘√‘¬“√–À«à“߇≈¥Õ–´’‡µ¥‰µ√‰Œ‡¥√µ ·≈–‡Õ∑‘≈’π‰°≈§Õ≈‚¥¬„™â “√ ‰µ√‡Õ∑‘≈’π‡µµ√–¡’π‡ªìπ§–µ–≈’ µå‡æ◊ËÕ„™â„π°“√º≈‘µ “√µ—Èßµâπ‚æ≈‘‡¡Õ√å§◊Õ‡≈¥‰°≈‚§‡≈µ [-PbOCH2CH2O-] ∑ ”§’Ë ≠™π— ¥Àπ‘ ßµ÷Ë Õ¢∫«π°“√𔉪„™à „π°“√ â ߇§√“–À— å “√‰¥Õ‡≈§µ√‘ °™π‘ ¥µ‘ “ßÊà ‰¥·°â à “√‡øÕ√‚√‰¥Õå ‡≈§µ√‘ °‘ “√·Õπ‰∑‡øÕ√å‚√Õ‘‡≈§µ√‘°·≈– “√‡æ’¬‚´‰¥Õ‘‡≈§µ√‘°®“°°“√ —߇§√“–Àå¥â«¬ “√ª√–°Õ∫ÕÕ°‰´¥å‡æ’¬ß ¢—ÈπµÕπ‡¥’¬«∑’ˇ√’¬°«à“ Oxide One Pot Synthesis (OOPS) ∑”„À≥⠓√µ—Èßµâπ‡≈¥‰°≈‚§‡≈µ¡’ ¡∫—µ‘∑“߉øøÑ“ ¥’°«à“‡≈¥Õ–´’‡µ¥‰µ√‰Œ‡¥√µ πÕ°®“°π’Ȭ—ß “¡“√∂𔉪„™âº ¡°—∫ “√µ—Èßµâπ™π‘¥Õ◊ËπÊ ‡™àπ ‰∑∑“‡π’¬¡ ‰°≈‚§‡≈µ·≈–‚´‡¥’¬¡∑√’ ‰°≈‚§‡´Õ√傧‡πµ‡æ◊ËÕº≈‘µ‡≈¥‰∑∑“‡πµ ‡≈¥‡´Õ√傧‡πµ·≈–‡≈¥‡´Õ√傧‡πµ ‰∑∑“‡πµ ‚¥¬ºà“π°√–∫«π°“√‚´≈-‡®≈∑√“π ‘™—Ëπ Key Words : OOPS, Sol-gel process, Dielectric materials §” ”§—≠ : OOPS °√–∫«π°“√‚´≈-‡®≈ «— ¥ÿ‰¥Õ‘‡≈§µ√‘° * Ph.D.
    [Show full text]
  • The Titanium Industry: a Case Study in Oligopoly and Public Policy
    THE TITANIUM INDUSTRY: A CASE STUDY IN OLIGOPOLY AND PUBLIC POLICY DISSERTATION Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy In the Graduate School of the Ohio State University by FRANCIS GEORGE MASSON, B.A., M.A. The Ohio State University 1 9 5 k Content* L £MR I. INTRODUCTION............................................................................................... 1 II. THE PRODUCT AND ITS APPLICATIONS...................................... 9 Consumption and Uses ................................. 9 Properties ........................................................ ...... 16 III. INDUSTRY STRUCTURE................................................................................ 28 Definition of the I n d u s t r y ............................................ 28 Financial Structure. ..••••••.••. 32 Alloys and Carbide Branch. ........................... 3 k Pigment Branch .............................................................................. 35 Primary Metal Branch ................................. 1*0 Fabrication Branch ................................. $0 IT. INDUSTRY STRUCTURE - CONTINUED............................................. $2 Introduction ................................ $2 World Production and Resources ................................. $3 Nature of the Demand for Ram Materials . $8 Ores and Concentrates Branch. ••••••• 65 Summary.................................................................. 70 V. TAXATION. ANTITRUST AND TARIFF POLICY............................
    [Show full text]
  • ET107, Dehydrated Alcohol, 200 Proof, Undenatured, USP
    Scientific Documentation ET107, Dehydrated Alcohol, 200 Proof, Undenatured, USP Not appropriate for regulatory submission. Please visit www.spectrumchemical.com or contact Tech Services for the most up‐to‐date information contained in this information package. Spectrum Chemical Mfg Corp 769 Jersey Avenue New Brunswick, NJ 08901 Phone 732.214.1300 Ver4.05 16.October.2020 ET107, Dehydrated Alcohol, 200 Proof, Undenatured, USP Table of Contents Product Specification Certificate of Analysis Sample(s) Safety Data Sheet (SDS) Certification of Current Good Manufacturing Practices (cGMP) Manufacturing Process Flowchart Source Statement BSE/TSE Statement Allergen Statement EU Fragrance Allergen Statement GMO Statement Melamine Statement Nitrosamine Statement Animal Testing Statement Organic Compliance Statement Shelf Life Statement Other Chemicals Statement Elemental Impurities Statement Residual Solvents Statement General Label Information – Sample Label General Lot Numbering System Guidance Kosher Certificate Specification for Dehydrated Alcohol, 200 Proof, Undenatured, USP (ET107) Item Number ET107 Item Dehydrated Alcohol, 200 Proof, Undenatured, USP CAS Number 64-17-5 Molecular Formula C2H5OH Molecular Weight 46.07 MDL Number Synonyms Absolute Ethyl Alcohol ; Anhydrous Ethanol ; Ethanol ; Grain Derived Alcohol Test Specification Min Max ASSAY (by VOLUME) 99.5 % NOT MORE OPALESENT CLARITY OF SOLUTION THAN STANDARD NOT MORE INTENSE THAN COLOR OF SOLUTION STANDARD ACIDITY OR ALKALINITY SOLUTION IS PINK SPECIFIC GRAVITY @ 15.56oC 0.7962 UV ABSORPTION: 240 nm 0.40 250 - 260 nm 0.30 270 - 340 nm 0.10 ORGANIC IMPURITIES: METHANOL 200 μL/L ACETALDEHYDE AND ACETAL 10 μL/L BENZENE 2 μL/L SUM OF ALL OTHER IMPURITIES 300 μL/L LIMIT OF NONVOLATILE RESIDUE 2.5 mg ELEMENTAL IMPURITIES AS REPORTED IDENTIFICATION A 0.7962 SPECTRUM MATCHES IDENTIFICATION B REFERENCE IDENTIFICATION (C) LIMIT OF METHANOL 200 μL/L CERTIFIED KOSHER APPEARANCE EXPIRATION DATE DATE OF MANUFACTURE RESIDUAL SOLVENTS AS REPORTED CLASS 3 (solvent) / 1-PROPANOL .
    [Show full text]
  • Silver Perchlorate
    Aug. 20, 1937 SILVERPERCHLORATE AND NITRATE COMPLEXES WITH ALKYNES 434 I refractive index corresponds with that of a mixture contain- method for the separation of a-pinene and &pinene from ing 51.1% a-pinene. each other. The mixture, 2.05 g., was treated with silver perchlorate, Preparation of Silver Nitrate-Cyclohexene Complex.l5- 0.75 e., and left to stand at 25' for 7 hr., when the products Silver nitrate, 3.6 g., was dissolved in a warm mixture of were-separated by the method described abo;e. The cyclohexene, 15 ml., and ethanol, 2 ml. At room tempera- liquid, 1.00 g. (49%), distilled from the mixture had aZ5D ture a system of two colorless phases was formed, and at 0" +30.7", ~Z~LD1.4662. These figures correspond with those the lower phase gave a mass of needle-shaped crystals. of a mixture of a-pinene with @-pinenecontaining 78.3 and Filtration at ca. 4' gave 4.6 g. of product, m.p. 24-32'. 78.2y0 a-pinene, respectively. The liquid, 0.60 g. (297c), Anal. Calcd. for AgNOs.2CsHio: Ag, 32.3. Found: obtained by treating the solid phase with water, 2 ml., had Ag, 33.2, 33.3. aZ5~-14.7', n25~1.4756. These figures correspond with Pinenes and Silver Nitrate.-Attempts to obtain a solid those of a mixture cmtaining 92.2 and %.lyO8-pinene, re- complex were unsuccessful with pinene (practical) or pinene spectively. The agreement between the two methods of diluted with a solvent, for example, acetone, methanol or analysis for both fractions confirms that no chemical change ethanol.
    [Show full text]
  • United States Patent (19) 11 4,260,645 Kerr Et Al
    United States Patent (19) 11 4,260,645 Kerr et al. 45) Apr. 7, 1981 LATENT FINGER PRINT DETECTION 54 OTHER PUBLICATIONS 75 Inventors: F. Michael Kerr, Ottawa; Alan D. Sharp, D. W. A. et al., J. Chem. Soc., Part II, pp. Westland, Chelsea, both of Canada 1855-1858 (1956). 73 Assignee: Canadian Patents and Development C.A., vol. 63,9729d (1965). Limited, Ottawa, Canada C.A., vol. 48, 13520d (1954). 21 Appl. No.: 508 C.A., vol. 61, 6894g (1964). C.A., vol. 48,5704i (1954). 22 Fied: Jan. 2, 1979 C.A., vol. 53, 6866a (1959). 51 int. Cl.......................... B41M 5/00; C09K 3/30; C.A., vol. 48, 3080i (1954). C09K 3/00; G01N 33/16 Primary Examiner-Teddy S. Gron 52 U.S. C. .......................................... 427/1; 106/19; 106/21; 118/31.5; 252/182; 252/408; 422/61 Attorney, Agent, or Firm-Alan A. Thomson 58) Field of Search .................... 106/19, 21; 252/182, 57 ABSTRACT 252/408; 422/61; 118/31.5; 427/1 Latent fingerprints can be detected and visualized by 56) References Cited application to the suspected locale, of a solution, in a U.S. PATENT DOCUMENTS volatile organic solvent of selected silver salts soluble in said solvent. Suitable salts include silver perchlorate 2,235,632 3/1941 Heinecke ............................... 106/21 3,075,852 1/1963 Bonora ..... ... 8/31.5 and silver trifluoroacetate. The solution is preferably 3,148,277 9/1964 Lewanda .. ... 8/31.5 applied as a spray. This non-aqueous solution minimizes 4,182,261 / 1980 Smith et al.
    [Show full text]
  • Circular of the Bureau of Standards No. 539 Volume 5: Standard X-Ray
    : :;.ta^4aya9 . Bl.ig NBS CIRCULAR 539 VOLUME V Reference taken Standard X-ray Diffraction Powder Patterns UNITED STATES DEPARTMENT OF COMMERCE NATIONAL BUREAU OF STANDARDS Standard X-ray Diffraction Powder Patterns The four previously issued volumes in this series are avail- able from the Superintendent of Documents, U. S. Govern- ment Printing Office, Washington 25, D. C., as follows: NBS Circular 539, Volume I, Standard X-ray Diffraction Powder Patterns (Data for 54 inorganic substances) NBS Circular 539, Volume II, Standard X-ray Diffraction Powder Patterns (Data for 30 inorganic substances) NBS Circular 539, Volume III, Standard X-ray Diffraction Powder Patterns (Data for 34 inorganic substances) NBS Circular 539, Volume IV, Standard X-ray Diffraction Powder Patterns (Data for 42 inorganic substances) The price of each volume is 45 cents. Send orders with remittance to: Superintendent of Documents, Government Printing Office, Washington 25, D. C. UNITED STATES DEPARTMENT OF COMMERCE • Sinclair Weeks, Secretary NATIONAL BUREAU OF STANDARDS • A. V. Astin, Director Standard X-ray Diffraction Powder Patterns Howard E. Swanson, Nancy T. Gilfrich, and George M. Ugrinic National Bureau of Standards Circular 539 Volume V, Issued October 21, 1955 For sale by the Superintendent of Documents, U. S. Government Printing Office, Washington 25, D. C. Price 45 cents CONTENTS Page Page Introduction 1 Standard X-ray powder patterns—Continued Standard X-ray powder patterns: Lead titanate, PbTi0 3 39 Ammonium chloroplatinate, (NH 4 ) 2 PtCl 6 3 Magnesium tin, Mg 2 Sn 41 Ammonium chlorostannate, (NH 4 ) 2 SnCl 6 4 Magnesium titanate (geikielite), MgTi0 3 43 Ammonium fluosilicate (cryptohalite), Manganese (II) oxide, (manganosite) MnO._ 45 (NH 4 ) 2 SiF6 5 Molybdenum disulfide (molybdenite), MoS 2 _.
    [Show full text]
  • University of Groningen Targeted Diazotransfer to Proteins Lohse, Jonas
    University of Groningen Targeted diazotransfer to proteins Lohse, Jonas IMPORTANT NOTE: You are advised to consult the publisher's version (publisher's PDF) if you wish to cite from it. Please check the document version below. Document Version Publisher's PDF, also known as Version of record Publication date: 2018 Link to publication in University of Groningen/UMCG research database Citation for published version (APA): Lohse, J. (2018). Targeted diazotransfer to proteins. University of Groningen. Copyright Other than for strictly personal use, it is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), unless the work is under an open content license (like Creative Commons). The publication may also be distributed here under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license. More information can be found on the University of Groningen website: https://www.rug.nl/library/open-access/self-archiving-pure/taverne- amendment. Take-down policy If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Downloaded from the University of Groningen/UMCG research database (Pure): http://www.rug.nl/research/portal. For technical reasons the number of authors shown on this cover page is limited to 10 maximum. Download date: 09-10-2021 Cover design: Andrej Horoschun, https://horoschun.artstation.com/ ISBN (print) 978-94-034-0733-3
    [Show full text]
  • Magnificent Molecules Urea Ian Le Guillou Finds out What Skin Creams, Pretzels and Fertilisers Have in Common
    Magnificent molecules Urea Ian Le Guillou finds out what skin creams, pretzels and fertilisers have in common Urea was the first molecule from a living organism to be highest percentage nitrogen content of solid fertilisers, synthesised in a lab. The honour for this achievement which means less weight is required and it is cheaper to goes to Friedrich Wöhler, who synthesised urea in Berlin transport. The urea typically decomposes into ammonia, in 1828 by reacting silver cyanate and ammonium which can be absorbed by plants. However, ammonia chloride. As so often happens in these stories, Wöhler tends to evaporate, reducing the amount of nitrogen never intended to make urea, but was actually trying to available in the soil. To avoid this, particularly during make ammonium cyanate. However, the significance of the summer, farmers will spread the urea on fields just his discovery was so great that he is now before it is due to rain. known as the father of organic chemistry. The ammonia can also be oxidised by bacteria A little accident in the soil, creating nitrates. Nitrates are easily Before Wöhler, it was still possible to get Urea absorbed by plants, but can be carried away hold of urea but it doesn’t sound pleasant in rain water, running off into nearby lakes and – Herman Boerhaave purified urea from urine 100 rivers. This is a growing problem because it encourages years earlier. Boerhaave’s work on urea was somehow the growth of plants in the water, which can disrupt the forgotten and 50 years later a method for purifying urea local ecosystem.
    [Show full text]
  • Structure and Properties of Lead Zirconate Titanate Thin Films by Pulsed Laser Deposition GOH WEI CHUAN
    Structure and Properties of Lead Zirconate Titanate Thin Films by Pulsed Laser Deposition GOH WEI CHUAN (B.Sc (Hons), NUS) A THESIS SUBMITTED FOR THE DEGREE OF Doctoral of Philosophy Department of Physics National University of Singapore 2005 Acknowledgements I would like to express my deepest gratitude to my supervisors, Prof. Ong Chong Kim and Dr. Yao Kui. I would like to thank Prof. Ong for giving me the opportunity to study and perform research work in the Center of Superconducting and Magnetic Materials (CSMM). His passion and enthusiasm in the search for understanding the underlying physics of the experiments have deeply influenced my mindset in conducting experiments and will continue to be my source of inspiration and guidance. Without Prof. Ong’s constant guidance and criticism, I would have lost my bearing in the vast sea of knowledge, and would not have reached this far. I would also like to express my greatest appreciation to Dr. Yao Kui in Institute of Material Research and Engineering (IMRE). His constant advice and meticulous attention to the theoretical and experimental details had deeply influenced my way of research both in designing experiments and interpreting the results. Without his supervision and encouragements in countless hours of his time, it would not be possible for me to complete my publications and thesis. For that I am in debt to him and will forever remember his advice when pursuing my future endeavors. I am indebted to my fellow colleagues in CSMM, IMRE and Department of Physics, NUS, including A/P Sow Chorng Haur, Xu Sheng Yong, Wang Shi Jie, Li Jie, Yang Tao, Tan Chin Yaw, Rao Xue Song, Chen Lin Feng, Yan Lei, Kong Lin Bing, Liu Hua Jun, Lim Poh Chong, Yu Shu Hui, Gan Bee Keen and all those have shared their time helping me and discussing with me in this project.
    [Show full text]
  • Dielectric and Electrical Properties of Lead Zirconate Titanate
    Available online a t www.derpharmachemica.com Scholars Research Library Der Pharma Chemica, 2015, 7(10):175-185 (http://derpharmachemica.com/archive.html) ISSN 0975-413X CODEN (USA): PCHHAX Dielectric and electrical properties of lead zirconate titanate R. Balusamy a, P. Kumaravel b and N. G. Renganathan c* aDepartment of Mechanical Engineering, Al-Ameen Engineering College, Erode bDepartment of Mechanical Engineering, Institute of Road and Transport Technology, Erode c School of Basic Sciences, Vel Tech University, Chennai _____________________________________________________________________________________________ ABSTRACT o Lead zirconate titanate (PZT) (P bZrO3- PbTiO3) were prepared by mixed oxide method at 1100 C. Crystalline nature of the synthesized PZT has been confirmed by X-ray powder diffraction studies. The particle size and strain is calculated from X-ray peak broadening analysis by using Williamson-Hall plot. The crystallite size is also calculated using Debye-Scherrer’s formula. Also, the surface morphology and particle size of the samples were imaged using scanning electron microscopy (SEM). Dielectric measurement demonstrates that decrease in dielectric constant with increase in temperature. The temperature dependence of the ac conductivity indicated that the conduction process is due to singly ionized (in ferroelectric region) and doubly ionized (in paraelectric region). Key words : PZT ceramics, dielectric spectroscopy, dielectric losses, SEM. _____________________________________________________________________________________________ INTRODUCTION Lead zirconate titanate (PZT) – a ferroelectric ceramic material has piezoelectric properties and reciprocal behavior. This material is used to convert electrical energy into mechanical energy and vice-versa. The material properties of PZT have been the subject for significant research in recent years due to its excellent applications in micro- electromechanical (MEMS) and nano-electromechanical (NEMS) devices.
    [Show full text]
  • Tin Titanate – the Hunt for a New Ferroelectric Perovskite
    Tin Titanate – the hunt for a new ferroelectric perovskite J. Gardner,1 Atul Thakre,2,3 Ashok Kumar,2,3 J. F. Scott,1,4 1 School of Chemistry, University of St. Andrews, St. Andrews, KY16 9ST, United Kingdom 2 CSIR-National Physical Laboratory (CSIR-NPL), Dr. K. S. Krishnan Road, Delhi 110012, India 3 Academy of Scientific and Innovative Research (AcSIR), CSIR-NPL Campus, Dr. K. S. Krishnan Road, Delhi 110012, India 4 School of Physics and Astronomy, University of St. Andrews, St. Andrews, Fife KY16 9SS, United Kingdom Email: [email protected] and [email protected] Abstract We review all the published literature and show that there is no experimental evidence for homogeneous tin titanate SnTiO3 in bulk or thin-film form. Instead a combination of unrelated artefacts are easily misinterpreted. The X-ray Bragg data are contaminated by double scattering from the Si substrate, giving a strong line at the 2-theta angle exactly where perovskite SnTiO3 should appear. The strong dielectric divergence near 560K is irreversible and arises from oxygen site detrapping, accompanied by Warburg/Randles interfacial anomalies. The small (4 uC/cm2) apparent ferroelectric hysteresis remains in samples shown in pure (Sn,Ti)O2 rutile/cassiterite, in which ferroelectricity is forbidden. Only very recent German work reveals real bulk SnTiO3, but this is completely inhomogeneous, consisting of an elaborate array of stacking faults, not suitable for ferroelectric devices. Unpublished TEM data reveal an inhomogeneous SnO layered structured thin films, related to shell-core structures. The harsh conclusion is that there is a combination of unrelated artefacts masquerading as ferroelectricity in powders and ALD films; and only a trace of a second phase in Cambridge PLD data suggests any perovskite content at all.
    [Show full text]