Acidic Melts Research Articles

Solid phase synthesis and structural characterization of an oxo-molybdenum(V) porphyrin: triplet state ESR spectrum of μ-oxo bridged molybdenum(V) dimer

The solid state synthesis of molybdenum porphyrin using [ Mo ( NO )2( py )2( Cl )2] as the metal source and H 2 TPP (5,10,15,20-meso-tetraphenylporphyrin) in 3,5-dinitrobenzoic acid melt is described. Complex [ Mo V O ( TPP )(3,5- DNB )] (1) (3,5-DNB = 3,5-dinitrobenzoate ion) is isolated in almost quantitative yield. 1 is characterized by single-crystal X-ray structure analysis, electron paramagnetic resonance, electronic, FT-IR spectroscopy, and by magnetic moment measurements. 1 in basic alumina column on elution with DCM/Ethyl acetate as solvent hydrolyzed to μ-oxo bridged dimeric molybdenum(V) complex [{ Mo V ( O )( TPP )}2 O ] (2). 2 shows a interesting triplet state ESR spectrum in the solid state with half field signal suggesting two independent Mo ( V ) centers in the complex.

Solid-state actinide acid phosphites from phosphorous acid melts

The reaction of UO3 and H3PO3 at 100°C and subsequent reaction with dimethylformamide (DMF) produces crystals of the compound (NH2(CH3)2)[UO2(HPO2OH)(HPO3)]. This compound crystallizes in space group P21/n and consists of layers of uranyl pentagonal bipyramids that share equatorial vertices with phosphite units, separated by dimethylammonium. In contrast, the reaction of phosphorous acid and actinide oxides at 210°C produces a viscous syrup. Subsequent dilution in solvents and use of standard solution-state methods results in the crystallization of two polymorphs of the actinide acid phosphites An(HPO2OH)4 (An=U, Th) and of the mixed acid phosphite–phosphite U(HPO3)(HPO2OH)2(H2O)·2(H2O). α- and β-An(HPO2OH)4 crystallize in space groups C2/c and P21/n, respectively, and comprise a three-dimensional network of An4+ cations in square antiprismatic coordination corner-sharing with protonated phosphite units, whereas U(HPO3)(HPO2OH)2(H2O)2·(H2O) crystallizes in a layered structure in space group Pbca that is composed of An4+ cations in square antiprismatic coordination corner-sharing with protonated phosphites and water ligands. We discuss our findings in using solid inorganic reagents to produce a solution-workable precursor from which solid-state compounds can be crystallized.

Preparation of LaB3O6:Eu3+ phosphors by a facile precursor method and their luminescent properties

The LaB3O6:Eu3+ phosphors were prepared by calcining the precursors which were synthesized by boric acid melting method using rare earth oxide and boric acid as raw materials, and they were characterized by EDS, XRD, IR, SEM and PL. The influences of reaction temperature for the preparation of precursor and subsequent calcination temperature and time of precursor on the luminescence properties of LaB3O6:Eu3+ phosphor were investigated. The results showed that the LaB3O6:Eu3+ phosphors with maximum luminescent intensity were obtained by calcining precursor at 1000°C for 6h, in which the precursor was prepared at 200°C for 72h. Compared with the conventional high temperature solid-state reaction method, the pure LaB3O6:Eu3+ phosphor can be obtained at relatively lower calcination temperature by the precursor method and exhibits much stronger emission intensity.

Manufacturing Technique and Property Evaluations of Conductive Nonwoven Fabrics

Conductive textiles can be used in diverse fields, such as antistatic materials, sensors, materials for electromagnetic shielding and biomedical. This study produces nonwoven fabrics with polylactic acid (PLA) and polyaniline (PAN) and the resulting PLA/PAN nonwoven fabrics are evaluated with electromagnetic shielding effectiveness (EMSE) and air permeability. Polylactic acid (PLA) and low melting point polylactic acid (LPLA) are made into nonwoven fabrics, which are then spray-coated with different amount of PAN solution to form PLA/PAN nonwoven fabrics. The fabrics are laminated with various numbers of layers, and then thermally pressed. The experiment results show that the PAN amount and lamination number are proportional to the EMSE of the PLA/PAN nonwoven fabrics.

Investigation on fluoroacidity of molten fluorides solutions in relation with mass transport

Equilibria between species in solution and its corresponding gaseous species were investigated in various molten fluorides mixtures. From the measurements of boron and silicon kinetic constant of gas release, a relative fluoroacidity scale of solvents was proposed. Due to very high kinetic rates of SiF4(g) and BF3(g) release for the most acidic melts, another approach to evaluate fluoroacidity based on mass transport was considered. Relationships between bridging fluorine atoms, viscosity and fluoroacidity was demonstrated. Diffusion coefficients of Si(IV) and B(III) ions were measured and correlated to the viscosity through the Schmidt number (Sc) defined as the ratio between solvent viscosity and solute diffusivity. These results confirmed the fluoroacidity scale previously obtained, validating the original approach developed on mass transport.

Speciation of cobalt-chloride-based ionic liquids and electrodeposition of Co wires

The speciation and coordination of cobalt-chloride-based ionic liquids with various mole percentages of CoCl2 were investigated using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS), X-ray absorption spectroscopy (XAS), ultraviolet-visible absorption spectroscopy, and cyclic voltammetry. The coordination number and the mean Co-Cl bond length decreases with increasing CoCl2 concentration, indicating that various Co(II) chloride compounds such as CoCl42-, Co2Cl5-, and Co3Cl7− are formed depending on the molar ratio of CoCl2 and EMIC in the melt. While the [CoCl4]2− complex formed in the Lewis basic melts and is electrochemically inactive within the electrochemical window of the melt, the other coordination-unsaturated cobalt chloride compounds formed in Lewis acidic melts can be electrochemically reduced to cobalt metal. The template-free electrodeposition of Co nanowires can be achieved from 40-60 mol% and 50-50 mol% CoCl2-EMIC (1-ethyl-3-methylimidazolium chloride) ionic liquids without any additives. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were used to characterize the surface of the deposits.

Unusual acid melts in the area of the unique Rosia Montana gold deposit, Apuseni Mountains, Romania: Evidence from inclusions in quartz

Crystalline and melt inclusions were studied in large (up to 2 cm across) dipyramidal quartz phenocrysts from Miocene dacites in the area of the Rosia Montana Au-Ag deposit in Romania. Data were obtained on the homogenization of fluid inclusions and the composition of crystalline inclusions and glasses in more than 40 melt inclusions, which were analyzed on a electron microprobe. The minerals identified in the crystalline inclusions are plagioclase (An 51–62), orthoclase, micas (biotite and phengite), zircon, magnetite (TiO2 = 2.8 wt %), and Fe sulfide. Two types of the melts were distinguished when studying the glasses of the melt inclusions. Type 1 of the melts is unusual in composition. The average composition of 20 inclusions is as follows (wt %): 76.1 SiO2, 0.39 TiO2, 6.23 Al2O3, 4.61 FeO, 0.09 MnO, 1.64 MgO, 3.04 CaO, 2.79 Na2O, 3.79 K2O (Na2O/K2O = 0.74), 0.07 P2O5, 0.02 Cl. The composition of type 2 of the melts is typical of acid magmas. The average of 23 inclusion analyses is (wt %) 79.3 SiO2, 0.16 TiO2, 10.27 Al2O3, 0.63 FeO, 0.08 MnO, 0.29 MgO, 1.83 CaO, 3.56 Na2O, 2.79 K2O (Na2O/K2O = 1.28), 0.08 P2O5, 0.05 Cl. The compositions of these melts significantly differ in concentrations of Ti, Al, Fe, Mg, Ca, Na, and K. The high analytical totals of the analyses (close to 100 wt %, more specifically 98.9 and 99.0 wt %, respectively) testify that the melts were generally poor in water. Two inclusions of type 1 and two inclusions of type 2 were analyzed on an ion probe, and their analyses show remarkable differences in the concentrations of certain trace elements. These concentrations (in ppm) are for the melts of types 1 and 2, respectively, as follows: 10.0 and 0.69 for Be, 29.3 and 5.7 for B, 6.4 and 1.4 for Cr, 146 and 6.9 for V, 74 and 18 for Cu, 92 and 29 for Rb, 45 and 15 for Zr, 1.7 and 0.6 for Hf, 10.3 and 2.3 for Pb, and 52 and 1.3 for U. The Th/U ratio of these two melt types are also notably different: 0.04 and 0.19 for type 1 and 2.0 and 2.9 for type 2. These data led us to conclude that the magmatic melts were derived from two different sources. Our data on the melts of type 1 testify that the magmatic chamber was contaminated with compositionally unusual crustal rocks (perhaps, sedimentary, metamorphic, or hydrothermal rocks enriched in Si, Fe, Mg, U, and some other components). This can explain the ore-forming specifics of magmatic chambers in the area.

Characterization of the phase structure of proton exchanged channel waveguides in Z cut LiNbO3 using wet etching technique

We report the results of a systematic study of the structure of channel waveguides fabricated on Z cut LiNbO3 in benzoic acid melt. It was found that the proton-exchange region consists of three phases of HxLi1−xNbO3 solid solution.

In silico Analysis of TCR Vβ7 of Two Patients with Type 1 Diabetes Mellitus

Objective:To compare the sequences and crystal structures of variable region of beta chain 7 (Vβ7) of T cell receptor (TCR) of two patients with type 1 diabetes mellitus (T1DM).Patients and Methods:The skewness of TCR Vβ7 of two T1DM patients were detected with real-time florescence quantitative polymerase chain reaction (FQ-PCR) and deoxyribonucleic acid (DNA) melting curve analysis technique followed by being sequenced, the crystal structures of them were simulated according to CPH models 2.0 Server, IMGT database, and RasMol 2 software.Results:The whole sequences of TCR Vβ7 of T1DM patient-1 were “CASRTAGQYEQYFGPGTR”, that of patient-2 were “CASRTAGQYEQFFGPGTR”; the only difference between them lied on the 12th amino acid. The crystal structures of Vβ7 of the two patients simulated with backbone model were rather similar, while that with sphere model were obviously different.Conclusion:Although the TCR Vβ7 of the T1DM patients share the similar gene sequences, their crystal structures simulated with sphere model are different, and the mechanism needs further study.

A Novel Fatty Acid Profile Index--the Lipophilic Index--and Risk of Myocardial Infarction

The lipophilic index (LI), a mean measure of fatty acid melting points, has been proposed to capture overall fatty acid profile and may play an important role in the etiology of coronary heart disease. We aimed to determine the association between LI in diet and in adipose tissue and metabolic risk factors for myocardial infarction (MI) and risk of MI. We used a population-based, matched case-control study of nonfatal first acute MI conducted in Costa Rica between 1994 and 2004, with 1,627 case-control pairs. The LI is defined as the mean of the melting points of specific fatty acids in diet or adipose tissue. LIs in diet and adipose tissue were significantly associated with higher plasma triglyceride concentrations, low-density lipoprotein cholesterol concentrations, and low-density:high-density lipoprotein cholesterol ratio. Comparing extreme quintiles for the LI in diet or adipose tissue, the odds ratios for MI were 1.57 (95% confidence interval: 1.22, 2.02; P for trend < 0.001) for dietary LI and 1.30 (95% confidence interval: 1.00, 1.69; P for trend = 0.02) for adipose tissue LI in the multivariable models. We hypothesize that a higher LI in diet and in adipose tissue represents decreased fatty acid fluidity and could play an important role in the etiology of coronary heart disease.

Cyclic Voltammetry and XAS Studies of Transition Metal Chlorides in the Ionic Liquid 1-Ethyl-3-Methyl Imidazolium Chloride/ Aluminum Chloride

Anhydrous nickel, niobium and tantalum chlorides were studied with cyclic voltammetry and X-ray absorption spectroscopy (XAS) in acidic and basic aluminum chloride/1-ethyl-3-methyl imidazolium chloride (EMIC) ionic liquids. Nickel chloride in an acidic melt displays metal stripping peaks which are not observed in the basic melt. XAS analysis shows that the nickel is tetrahedrally coordinated in the basic melt while in the acidic melt, it is coordinated by 6 chloride ions that are also associated with aluminum ions. For Nb2Cl10, the XAS data shows that the Nb has a coordination shell of 5 in both the acidic and basic melts, indicating that the Nb2Cl10 breaks up into two NbCl5 entities in both melts. For Ta2Cl10 in the acidic melt, the tantalum has five chlorides in its coordination shell. In the basic solution, the tantalum is coordinated by 7 chlorides. This indicates that the Lewis acidity of the tantalum chloride causes the Ta to coordinate differently in the acidic and the basic ionic liquids.

Electrochemical Investigation of Quinone Complexation by Lewis Acids in a Chloroaluminate Ionic Liquid

The electrochemical behavior of 9,10-anthraquinone (AQ) has been investigated in the initially neutral aluminum chloride : 1-ethyl-3-methylimidazolium chloride ionic liquid. It has been found that AQ is characterized by a single irreversible redox process in the neutral melt. Additions of AlCl3 cause a positive potential shift, first by the formation of two reversible redox processes corresponding to AlCl3 complexes of AQ under mildly acidic conditions, and then by the appearance of a shifted irreversible redox process in an acidic melt. HfCl4 additions cause similar behavior, except that the reversible systems persist at higher Lewis acid levels than for AlCl3. At the 11:1 Lewis acid: AQ point, AQ is still soluble as an orange solution for AlCl3 additions, but a yellow solid precipitates from a yellow (amber) solution for HfCl4 additions.

Synthesis and characterization of novel fluorinated pyridine-based polyimides

New pyridine-containing polyimides based on fluorinated γ-Х-pyridylenediamines (X=H, Cl, NH2, O-linkage) and dianhydride 6FDA were prepared by one-step polycondensation in benzoic acid melt. Molecular weight of the polymers enlarges with an increase of nucleophilicity of the pyridylenediamines and solubility of the macromolecules in the reaction medium. 4,4′-Oxydianiline was used as a co-monomer to prepare high-molecular pyridine-containing PI films with good mechanical properties. The polyimides and co-polyimides obtained are soluble in amide solvents, have good thermal and thermooxidative characteristics. Parameters of the polyimides pyrolysis, which provide consecutive elimination of different elements, were found.

Effect of the ethylene-acrylic acid melt index on the structural characteristics and properties of high-density polyethylene/layered double hydroxide nanocomposites prepared via the master-batch method

High-density polyethylene/Mg2Al-layered double hydroxide nanocomposites with different ethylene-acrylic acid random copolymer/Mg2Al-layered double hydroxide master batches were prepared by melt-mixing. The effect of the ethylene-acrylic acid random copolymer melt index on the exfoliated/intercalated nanocomposite structures was investigated by X-ray diffraction, transmission electron microscopy, Fourier transform infrared spectroscopy and scanning electron microscopy. The crystallization behavior and thermal property of the nanocomposites were determined via differential scanning calorimetry, thermogravimetric analysis, dynamic mechanical analysis and cone calorimetry. The Mg2Al-layered double hydroxide layers were well-dispersed at the nanometer level, providing direct evidence of the formation of intercalated/exfoliated nanocomposites, as well as the important effect of ethylene-acrylic acid random copolymer melt index on these structures and their properties. Lower ethylene-acrylic acid random copolymer melt index resulted in higher exfoliation and better dispersion of layered double hydroxide in the high-density polyethylene matrix. Reductions in the heat release rate, total heat release and the carbonic oxide and carbon dioxide production of the nanocomposites were also observed. These phenomena led to higher thermal stability and changes in the storage modulus, tan δ and loss modulus of the nanocomposites, as well as improvement in the heterogeneous nucleation effect of layered double hydroxide on high-density polyethylene.

Proton-exchanged optical waveguides in LiTaO3: phase composition and stress

Planar optical waveguide layers were obtained in Z-cut LiTaO3 crystal substrates via proton exchange. Two different media were used as proton sources: benzoic acid melt and lithium hydrogensulphate vapors, controlling the thickness of the waveguides by duration and temperature of the proton exchange process and also by post-exchange annealing. The intrinsic stress caused by the penetration of the hydrogen ions into the crystal lattice was estimated by the optical integral method. The phase composition of proton-exchanged layers was analyzed based on the mode and IR-absorption spectra. An attempt to relate the level of stress to the level of proton doping has been made.

Inorganic–Organic Hybrid Materials Based on Amino Acid Modified Hydrotalcites Used as UV‐Absorber Fillers for Polybutylene Succinate

AbstractPolybutylene succinate (PBS)‐functionalized nanocomposites with amino acid tyrosine (TYR)‐ and tryptophan (TRY)‐hybrid‐interleaved layered double hydroxide (LDH) materials exhibit interesting anti‐UV properties and rheological properties. Embedding amino acid into the layered double hydroxide container preserves the UV shielding property of the pristine organic molecule. When employed in an aliphatic polymer such as PBS, chain scission occurs during photoageing and accelerates the degradation of the raw material. However the embedded inorganic amino acid melt blended with PBS prevents such degradative phenomenon. An investigation of their structure–property relationship (i.e., nonmiscibility and expanded PBS nanocomposite structures) was conducted. The nonmiscible structure observed for LDH‐TYR was found to be associated with a chain‐extender behaviour, whereas the interleaved structure of PBS‐LDH‐TRY yielded a liquid–gel transition. Both PBS nanocomposite structures were found to be stable under agressive UV conditions, whereas amino acid free of an LDH container resulted in a deleterious effect when dispersed in PBS, largely promoting PBS chain scission. Hence amino acid organically modified hydrotalcites appear to hold promise for use as UV absorbers when dispersed into other aliphatic biodegradable polymers.

Phosphoric acid purification by suspension melt crystallization: Parametric study of the crystallization and sweating steps

AbstractIn order to purify phosphoric acid, the suspension melt crystallization process was studied. The suspension crystallization experiments were carried out with 80, 84 and 88 wt% phosphoric acid melt at the cooling rates of 0.05, 0.1 and 0.2 K/min, respectively. Sweating experiments were executed for various crystals obtained in suspension crystallization step. The purification effects of the sweating parameters including sweating time, initial inclusion amount and initial impurity content were studied. The inclusion fraction increases with the increase in cooling rate. The inclusion fraction of the crystals which were formed with feed concentration of 84 wt% phosphoric acid melt is lowest among the three feed concentrations. Different impurities have different purification performances during sweating. High inclusion amount and low impurity concentration favor the purification of H3PO4·0.5H2O crystals during sweating.

Improving lactic acid melt polycondensation: The role of co‐catalyst

AbstractA study on lactic acid polycondensation under melt conditions was carried out and a preliminary assessment revealed tin powder as a very good catalyst for poly(lactic acid) (PLA) synthesis by melt polycondensation while confirming previous information on SnCl2 good performance. However, these catalysts also promoted side reactions leading to racemization and yellowing of the final polymer. The use of p‐toluenesulphonic acid (p‐TSA) or triphenylphosphine (PPh3) as co‐catalysts proved to be very effective hindering colour formation and allowing synthesizing PLA samples with enhanced properties. The addition of these compounds to neat tin powder increased the PLA optical purity, whereas their addition to SnCl2 speeded up the polymerization. A significant increase in molecular weight, from 32,500 to 52,000 g mol−1, was recorded, with the new catalytic system SnCl2/PPh3 showing catalytic activity comparable with the one reported in the literature for SnCl2/p‐TSA. Several characterization techniques were used for assessing polymer samples: the molecular weights were determined by SEC, thermal behavior measured by DSC, and racemization extent calculated from specific rotation measurements. UV/vis spectroscopy was confirmed as a powerful technique for evaluating yellowing of final polymers. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Emplacement, structural and P-T evolution of the &amp;tilde;346 Ma Miřetín Pluton (eastern Teplá-Barrandian Zone, Bohemian Massif): implications for regional transpressional tectonics

* �Correspondingauthor The calc-alkaline Miřetin Pluton (newly dated at 346 Ma ± 5 Ma; an U-Pb age obtained by laser-ablation ICP MS me- thod on zircons) is a NNE-SSW elongated intrusive body emplaced into the upper- to mid- crustal rocks of the Policka Unit (eastern Tepla-Barrandian Zone; Bohemian Massif). Its composition reveals similarities to other calc-alkaline granitoids, which are mostly interpreted as products of magma mixing between the basic magmas derived from mantle wedge above a subduction zone with crustally-derived acid melts. The conditions of magma crystallization estimated at 653-681 °C and 0.29-0.43 GPa roughly correspond to peak metamorphic evolution of the host volcano-sedimentary rocks of the northwestern part of the Policka and Hlinsko units. The Miřetin Pluton was emplaced into a NNE-SSW oriented transpressional domain, well recognized on a regional scale along the eastern margin of the Tepla-Barrandian Zone. During, or shortly after the magma emplacement, the Miřetin Pluton was affected by pervasive submagmatic to high-T solid-state deformation, reflecting an additional strain increment of regional transpression in a narrow zone of thermal softening. Sharply superimposed low-T solid-state fabric preserved along the western part of the Pluton was connected with normal shearing between the Policka Unit at the bottom and the overlying Hlinsko Unit after 335 Ma.

Inclusions of unusual acid melts in quartz from dacite of the Unique Au Deposit Roşia Montana (Romania)

Inclusions of unusual acid melts in quartz from dacite of the Unique Au Deposit Roşia Montana (Romania)