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Low Melting Point (low + melting_point)
Selected AbstractsMicrostructure and Properties of SiC Honeycomb StructuresADVANCED ENGINEERING MATERIALS, Issue 12 2008D. Galsterer In this work, a novel processing route was used for fabrication of porous beta-SiC materials below 1450,°C. Honeycomb structures, based on Si, C and Al, were extruded and afterwards converted into SiC based ceramics at temperatures between 1050,°C and 1450,°C in Ar atmosphere. A conversion temperature below 1450,°C was applied due to the low melting point of the used Si-Al-alloy. [source] N-Palmitoyl-4-Hydroxy- L -Proline Palmityl Ester: A Pseudoceramide that Provides Efficient Skin Barrier Repair and ProtectionINTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2006G. Vielhaber Ceramides are the main constituents of the epidermal permeability barrier, and it has been demonstrated that the application of ceramide enriched creams promotes epidermal barrier repair. However, nature-identical ceramides are extremely expensive and difficult to formulate. We therefore developed a new pseudoceramide, N-palmitoyl-4-hydroxy- l -proline palmityl ester (BIO391). Due to its low melting point of £60°C the pseudoceramide BIO391 can easily be incorporated into cosmetic formulations. In addition, it is very safe for use in cosmetics. The efficacy of the pseudoceramide BIO391 was investigated in vivo in a model for detergent-induced barrier disruption. Trans-epidermal water loss, redness, and skin hydration were recorded before and after barrier disruption as well as during the subsequent 9-day treatment with the test products. Barrier repair of skin treated with the pseudoceramide BIO391 was accomplished earlier than that of untreated and vehicle treated skin. Optimum barrier repair was achieved with 1.0% pseudoceramide BIO391 and optimum erythema reduction with 0.5% pseudoceramide BIO391. The optimum dosage could be reduced to 0.1% pseudo-ceramide by synergistic combination with 0.1% (-)-a-bisabolol. In addition, the pseudoceramide BIO391 proved to be as effective as nature-identical ceramides 2 and 3. In summary, N-palmitoyl-4-hydroxy- l -proline palmityl ester is a highly efficient barrier repair agent with efficacy equivalent to that of nature-identical ceramides, and it has excellent formulation properties. [source] Effect of potential on the corrosion behavior of a new titanium alloy for dental implant applications in fluoride mediaMATERIALS AND CORROSION/WERKSTOFFE UND KORROSION, Issue 2 2004A. M. Al-Mayouf Abstract The effect of fluoride ion concentration and pH on the corrosion behavior of TCA (60 Ti 10 Ag 30 Cu), which is a new Ti alloy with low melting point, pure Titanium (Ti), and TAV (TiAl6V4) was examined using open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) at different potentials. Results show that the corrosion resistance of TCA and Ti decrease at anodic potentials compared with results obtained at OCP. At one potential the corrosion resistance decrease depends on NaF concentration and pH. TAV shows less resistance against corrosion in fluoride containing saliva. TCA has potentials more positive than Ti and TAV due to surface enrichment of Cu and Ag as Ti dissolves which accelerates the cathodic reaction. Fluoride ion may not hinder the growth of oxide layers on the surfaces of the electrodes. It will have influence on the properties of the oxide layer causing them to be not protective against corrosion in acid media containing fluoride ions. [source] Comparison of halogen bonding and van der Waals and ,,, interactions in 4,5-dibromo-2-hexyloxyphenolACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Fabio D. Cukiernik The title compound, C12H16BrO2, is an interesting case of a simple organic molecule making use of five different types of intra- and intermolecular interactions (viz. conventional and nonconventional hydrogen bonds, and ,,,, Br...Br and Br...O contacts), all of them relevant in the molecular and crystal structure geometry. The molecules are strictly planar, with an intramolecular O,H...O hydrogen bond, and associate into two-dimensional structures parallel to (01) through two different types of halogen bonding. The planar structures, in turn, stack parallel to each other interlinked by C,H..., and ,,, contacts. Also discussed are the relevant structural features leading to the rather low melting point of the compound. [source] Mononuclear Mixed ,-Ketoester-alkoxide Compound of Titanium as a Promising Precursor for Low-Temperature MOCVD of TiO2 Thin Films,CHEMICAL VAPOR DEPOSITION, Issue 6 2003R. Bhakta A monomeric titanium complex suitable for liquid-injection MOCVD applications is synthesized and its molecular structure is determined by single-crystal X-ray diffraction. [Ti(OiPr)2 -(tbaoac)2] (see Figure), (tbaoac),=,tertiarybutylacetoacetonate), is a volatile alkoxide-(beta)diketonate precursor that has a low melting point and very good solubility in common organic solvents. [source] Pentafluorosulfanyl (SF5) Containing Energetic SaltsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2006Haixiang Gao Abstract New quaternary salts of pentafluorosulfanyl-substituted (SF5) N -methylimidazole (1), 4-amino-1,2,4-triazole (3) or pyridine (5) were prepared and characterized. Most of the salts exhibit good thermal stabilities and low melting points placing them in the ionic liquid class. Their densities range between 1.4 and 1.8 g/cm3. The standard enthalpies of formation for the new salts were calculated by the use of computationally feasible DFT(B3LYP) and MP2 methods in conjunction with an empirical approach based on densities of salts. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Tetraalkylammonium Salts of Weakly Coordinating Aluminates: Ionic Liquids, Materials for Electrochemical Applications and Useful Compounds for Anion InvestigationCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2009Ines Raabe Dr. Abstract Weak and robust? Tetraalkylammonium salts of weakly coordinating fluorinated alkoxyaluminates are easily accessible, chemically robust materials that show interesting physico-chemical properties like low melting points, high electrochemical stability and electric conductivity in weakly polar solvents such as CH2Cl2, Ph-F and toluene. In this study, we investigated the tetraalkylammonium salts of the weakly coordinating fluorinated alkoxyaluminates [pftb], ([Al(O(C(CF3)3)4],), [hfip], ([Al(OC(H)(CF3)2)4],) and [hftb], ([Al(OC(CH3)(CF3)2)4],) in order to obtain information on their undisturbed spectral and structural properties, as well as to study their electrochemical behavior (i.e., conductivities in non-polar solvents and electrochemical windows). Several of the compounds qualify as ionic liquids with melting points as low as 42,°C for [NBu4]+[hfip],. Simple and almost quantitative metathesis reactions yielding these materials in high purity were developed. These [NR4]+ salts serve as model compounds for undisturbed anions and their vibrational spectra,together with simulated spectra based on quantum chemical DFT calculations,were used for the clear assignment of the anion bands. Besides, the ion volumes of the anions (Vion([pftb],)=0.736,nm3, Vion([hftb],)=0.658,nm3, Vion([hfip],)=0.577,nm3) and their decomposition pathways in the mass spectrometric measurements have been established. The salts are highly soluble in non-polar solvents (up to 1.09,mol,L,1 are possible for [NBu4]+[hftb], in CH2Cl2 and 0.41,mol,L,1 for [NBu4]+[hfip], in CHCl3) and show higher molar conductivities if compared to [NBu4]+[PF6],. The electrochemical windows of CH2Cl2, CH3CN and 1,2-F2C6H4 using the [NBu4]+ aluminate electrolytes are up to +0.5,V/,0.7,V larger than those using the standard [NBu4]+[PF6],. [source] Cyclic Quaternary Ammonium Ionic Liquids with Perfluoroalkyltrifluoroborates: Synthesis, Characterization, and PropertiesCHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2006Zhi-Bin Zhou Dr. Abstract New cyclic quaternary ammonium salts, composed of N -alkyl(alkyl ether)- N -methylpyrrolidinium, -oxazolidinium, -piperidinium, or -morpholinium cations (alkyl=nC4H9, alkyl ether=CH3OCH2, CH3OCH2CH2) and a perfluoroalkyltrifluoroborate anion ([RFBF3],, RF=CF3, C2F5, nC3F7, nC4F9), were synthesized and characterized. Most of these salts are liquids at room temperature. The key properties of these salts,phase transitions, thermal stability, density, viscosity, conductivity, and electrochemical windows,were measured and compared to those of their corresponding [BF4], and [(CF3SO2)2N], salts. The structural effect on all the above properties was intensively studied in terms of the identity of the cation and anion, variation of the side chain in the cation (i.e., alkyl versus alkyl ether), and change in the length of the perfluoroalkyl group (RF) in the [RFBF3], ion. The reduction of Li+ ions and reoxidation of Li metal took place in pure N -butyl- N -methylpyrrolidinium pentafluoroethyltrifluoroborate as the supporting electrolyte. Such comprehensive studies enhance the knowledge necessary to design and optimize ionic liquids for many applications, including electrolytes. Some of these new salts show desirable properties, including low melting points, high thermal stabilities, low viscosities, high conductivities, and wide electrochemical windows, and may thus be potential candidates for use as electrolytes in high-energy storage devices. In addition, many salts are ionic plastic crystals. [source] | |||||||||||||