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Computer simulation of the infrared and Raman activity of pyrope garnet, and assignment of calculated modes to specific atomic motions

Tracey D. Chaplin、G. D. Price、Nancy L. Ross1998-08-01American Mineralogist

The lattice dynamics computer code PARAPOCS was successfully used to calculate the 240 vibrational frequencies of pyrope garnet, Mg 3 Al 2 Si 3 O 12 , at ambient conditions. The atomic displacement vectors (eigenvectors) for each frequency were also calculated and their symmetry relations analyzed with the aid of fact…

High-pressure geophysics and materialsCrystal Structures and PropertiesSolid-state spectroscopy and crystallography

Partial Stabilization of Tetragonal Zirconia in Oxynitride Glass‐Ceramics

Thomas Höche、Martin Deckwerth、Christian Rüssel1998-08-01Journal of the American Ceramic Society

Nitrogen (via a polymeric AlN precursor) and ZrO 2 are introduced into a MgO‐CaO‐Al 2 O 3 ‐SiO 2 ‐glass. Subsequent crystallization of the glass results in a fine‐grained oxynitride glass‐ceramic. The microstructure of the latter is found to be entirely different for nitrogen concentrations of 4.85 and 9.94 mol%. Not…

Ferroelectric and Piezoelectric MaterialsAdvanced ceramic materials synthesisMicrowave Dielectric Ceramics Synthesis

Synthesis and characterization of polyacrylamide-polyaniline conductive blends

Bibekananda Das、Sumit Kar、Suman Bhusan Chakraborty 等 5 位作者1998-08-01Journal of Applied Polymer Science

Conducting poly(acrylamide) films were synthesized by exposing the polyacrylamide films impregnated with ammonium peroxodisulphate, an oxidizing agent, to hydrochloric acid vapor and then to aniline vapor. The effects of varying the exposure time to aniline vapor and the resulting composite films of polyacrylamide–pol…

Electrochemical sensors and biosensorsConducting polymers and applicationsAnalytical Chemistry and Sensors

The Passivity and Breakdown of Beryllium in Aqueous Solutions

Mary Ann Hill、Darryl P. Butt、R. S. Lillard1998-08-01Journal of The Electrochemical Society

The passivity of 98.0% pure beryllium has been studied in ambient temperature aqueous solutions as a function of pH. Below solution pH 2, potentiodynamic polarization curves exhibited active dissolution at all applied anodic potentials. In solution pH 2 to 12.5 it is shown that beryllium exhibits passive anodic behavi…

Corrosion Behavior and InhibitionHydrogen embrittlement and corrosion behaviors in metalsNon-Destructive Testing Techniques

Viscous properties of nematic liquid crystals composed of biaxial molecules

Marcin Fiałkowski1998-08-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

This paper presents a further improvement of the mean-field method of obtaining the Leslie viscosity coefficients of biaxial nematic liquid crystals presented in our last paper [M. Fialkowski, Phys. Rev. E 55, 2902 (1997)]. We carry out the calculations without using simplifying procedures employed in the cited paper.…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesSurfactants and Colloidal Systems

Calcium Speciation and Exchange Between Blood and Extrapallial Fluid of the Quahog Mercenaria mercenaria (L.)

Padmaja Nair、William E. Robinson1998-08-01Biological Bulletin

Calcium and small organic molecules (e.g., tyrosine, MW 181 Da) introduced into the extrapallial fluid (EPF) of the quahog Mercenaria mercenaria exhibit rapid fluxes across the outer mantle epithelium and are distributed throughout the circulatory system within 3 h. Larger molecules (e.g., bovine serum albumin, MW 66,…

Environmental Toxicology and EcotoxicologyPhysiological and biochemical adaptationsCalcium Carbonate Crystallization and Inhibition

Real‐time three‐dimensional imaging of macroscopic structures

Wilson、Mark A. A. Neil、Juškaitis1998-08-01Journal of Microscopy

We describe an extremely simple method of obtaining optically sectioned images with conventional low-power imaging systems in real time. A single spatial frequency grid pattern is projected onto an object. Images taken at three spatial positions of the grid projection are processed to provide 3D images of macroscopic…

Advanced Electron Microscopy Techniques and ApplicationsSilicon Nanostructures and PhotoluminescenceDigital Holography and Microscopy

Crystal structure of macphersonite (Pb4SO4(CO3)2(OH)2): comparison with leadhillite

I. M. Steele、J. J. Pluth、A. Livingstone1998-08-01Mineralogical Magazine

Abstract The crystal structure of macphersonite (Pb 4 SO 4 (CO 3 ) 2 (OH) 2 , Pcab, a = 9.242(2), b = 23.050(5), c = 10.383(2) Å) from Leadhills, Scotland has been determined to an R = 0.053. The structure has many features in common with its polymorph leadhillite including three distinct types of layers. Layer A incl…

Crystal Structures and PropertiesX-ray Diffraction in CrystallographyMineralogy and Gemology Studies

Scanning Kelvin probe analysis of the potential distribution under small drops of electrolyte

Chider Chen、Carmel B. Breslin、F. Mansfeld1998-08-01Materials and Corrosion

The scanning Kelvin probe has been used to map the potential distribution under small drops of NaCl placed on carbon steel, galvanized steel, stainless steel and an aluminum alloy. The concentration of NaCl has been varied and the effect of chromate as inhibitor has been evaluated. In the absence of chromate local ano…

Corrosion Behavior and InhibitionFuel Cells and Related MaterialsHydrogen embrittlement and corrosion behaviors in metals

Phosphovanadylite; a new vanadium phosphate mineral with a zeolite-type structure

M.D. Medrano、Howard T. Evans、Hans‐Rudolf Wenk 等 4 位作者1998-08-01American Mineralogist

Phosphovanadylite, whose simplified formula is (Ba,Ca,K,Na) x [(V,Al) 4 P 2 (O,OH) 16 ] · 12H 2 O, is a new vanadium phosphate zeolite mineral found in the Phosphoria Formation at Monsanto’s Enoch Valley Mine, Soda Springs, Idaho. Its formula in more detail is (Ba 0.38 Ca 0.20 K 0.06 Na 0.02 ) ∑0.66 [P 2 (V 3.44 Al 0.…

Crystal Structures and PropertiesRadioactive element chemistry and processingChemical Synthesis and Characterization

Topological correlations in soap froths

Kwok Yip Szeto、Tomaso Aste、Wing Yim Tam1998-08-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

Correlation in two-dimensional soap froth is analyzed with the introduction of two point correlators and topological distance. Cells with an equal number of sides repel (with linear correlation) while cells with a different number of sides attract (with nonbilinear correlation) for nearest neighbors, which cannot be e…

Material Dynamics and PropertiesScientific Research and Discoveries

The effects of electric field on the electronic structure of a semiconductor quantum dot

Kai Chang、Jian‐Bai Xia1998-08-01Journal of Applied Physics

The effect of electric field on the electronic structure of a spherical quantum dot is studied in the framework of the effective-mass envelope-function theory. The dependence of the energy of electron states and hole states on the applied electric field and on the quantum dot size is investigated; the mixing of heavy…

Semiconductor Quantum Structures and DevicesQuantum Dots Synthesis And PropertiesAdvanced Semiconductor Detectors and Materials

Polylactones, 43. Polymerization of L-lactide catalyzed by zinc amino acid salts

Hans R. Kricheldorf、Dirk‐Olaf Damrau1998-08-01Macromolecular Chemistry and Physics

The usefulness of the zinc salts of five different amino acids or amino acid derivatives as polymerization catalyst of L-lactide was studied and compared. The five amino acid (derivatives) were: N-acetyl-glycine, N-tosylglycine, L-proline, L-pyroglutamic acid and N-acetyl-4-aminobenzoic acid. All polymerizations were…

biodegradable polymer synthesis and propertiesCollagen: Extraction and CharacterizationBiopolymer Synthesis and Applications

ASTM F739 Method for Testing the Permeation Resistance of Protective Clothing Materials: Critical Analysis with Proposed Changes in Procedure and Test-Cell Design

Daniel H. Anna、Edward T. Zellers、Robert Sulewski1998-08-01American Industrial Hygiene Association Journal

ASTM (American Society for Testing and Materials) Method F739-96 specifies a test-cell design and procedures for measuring the permeation resistance of chemical protective clothing. Among the specifications are open-loop collection stream flow rates of 0.050 to 0.150 L/min for a gaseous medium. At elevated temperature…

Polymer crystallization and propertiesTextile materials and evaluationsPolymer Science and PVC

Electrochemical Quartz Crystal Microbalance Studies of Poly(ortho‐toluidine) Films Exposed to Aqueous Perchloric Acid Solutions

Silvana A. Ramírez、A. Robert Hillman1998-08-01Journal of The Electrochemical Society

We describe electrochemical quartz crystal microbalance measurements on poly( o ‐toluidine) (PoT) films exposed to aqueous perchloric acid solutions (pH 0 to 2). Crystal impedance measurements show the films to behave rigidly. PC redox switching occurs in two stages and is accompanied by nonmonotonic mass changes that…

Conducting polymers and applicationsElectrochemical Analysis and ApplicationsAnalytical Chemistry and Sensors

Changes on storage of polyacid‐modified composite resins

Nicholson、Alsarheed1998-08-01Journal of Oral Rehabilitation

Two polyacid-modified composite resins, Dyract and Compoglass, have been studied for water-uptake on storage in three aqueous media, namely pure water, 0.9% NaCl and 1 M NaCl at 37 degrees C, and the results compared with those of a conventional composite resin, Pekafill. The equilibrium water-uptake of Dyract and Com…

Material Properties and Applications

Trace map of a general aperiodic Thue-Morse chain: Electronic properties

Anathnath Ghosh、Samit Karmakar1998-08-01Physical review. B, Condensed matter

We develop an analytical method, using a real-space renormalization-group technique, for calculating the trace maps of quasiperiodic or aperiodic substitutional sequences. This method is quite different from the standard method of calculating the trace map from the recursion relation of the transfer matrices. The stan…

Theoretical and Computational PhysicsGraph theory and applicationsQuasicrystal Structures and Properties

Application of Scanning Vibrating Electrode Techniques to Study the Degradation of Coil-Coated Steel at Edges

F. Zou、C. Barreau、R. Hellouin 等 5 位作者1998-08-01Materials science forum

The Scanning Vibrating Electrode Technique ( SVET ) has been applied to the study of the degradation of coil-coatings at edges. From the results it is shown that the amount of chromate and its availability in the polymer matrix will be important factors for the initiation of corrosion at edges. It is also shown that t…

Corrosion Behavior and InhibitionConcrete Corrosion and DurabilityNon-Destructive Testing Techniques

Physical Gelation in a Triblock Copolymer Solution: In Situ Study of Stress−Strain Behavior and Structural Development

Ralf Kleppinger、Martin van Es、N. Mischenko 等 5 位作者1998-08-01Macromolecules

An in situ study of the microstructure and mechanical properties of polystyrene−poly(ethylene−butylene)−poly styrene (SEBS) triblock copolymer gels was performed. Simultaneous time-resolved synchrotron radiation X-ray scattering and stress−strain measurements at extensions up to λ = 2 indicate that the macroscopic def…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesBlock Copolymer Self-Assembly