Treatment with bisphosphonates to mitigate calcification of elastin-containing bioprosthetic materials.

This study evaluated the ability of bisphosphonates (BPAs) of different molecular structures to mitigate the calcification of porcine aortic wall (PAW) and bovine jugular vein wall (BJVW). Tissues cross-linked with glutaraldehyde (GA) or diepoxide (DE) were modified with pamidronic acid (PAM), alendronic acid (ALE), neridronic acid (NER) (type 1 BPAs); 2-(2'-carboxyethylamino)ethylidene-1,1-bisphosphonic acid (CEABA), 2-(5-carboxypentylamino)ethylidene-1,1-bisphosphonic acid (CPABA) (type 2); and zoledronic acid (ZOL) (type 3). After implanting the tissue samples subcutaneously in 100 rats, calcification was examined using atomic absorption spectrophotometry (60-day explants) and light microscopy after von Kossa staining (10- and 30-day explants).

Interaction of a Ti⁻Cu Alloy with Carbon: Synthesis of Composites and Model Experiments.

Titanium carbide (TiC), is the most thermodynamically stable compound in the Ti-C-Cu system, which makes it a suitable reinforcement phase for copper matrix composites. In this work, the interaction of a Ti-Cu alloy with different forms of carbon was investigated to trace the structural evolution leading to the formation of in-situ TiC-Cu composite structures. The reaction mixtures were prepared from TiCu alloy ribbons and carbon black or nanodiamonds to test the possibilities of obtaining fine particles of TiC using ball milling and Spark Plasma Sintering (SPS).

Concomitant cocrystal and salt: no interconversion in the solid state.

A cocrystal and a molecular salt of β-alanine and DL-tartaric acid, CHNO·CHO, of the same chemical composition, were studied over a wide temperature range by single-crystal and powder X-ray diffraction. Neither the interconversion between the two phases nor any polymorphic transitions were observed in the temperature range from 100 K to the melting points. This contrasts with the solvent-mediated phase transition from the salt to the cocrystal in a slurry that has been documented earlier.

Fabrication of Porous Materials by Spark Plasma Sintering: A Review.

Spark plasma sintering (SPS), a sintering method that uses the action of pulsed direct current and pressure, has received a lot of attention due to its capability of exerting control over the microstructure of the sintered material and flexibility in terms of the heating rate and heating mode. Historically, SPS was developed in search of ways to preserve a fine-grained structure of the sintered material while eliminating porosity and reaching a high relative density. These goals have, therefore, been pursued in the majority of studies on the behavior of materials during SPS.

Crystal structure of a 1:1 salt of 4-amino-benzoic acid (vitamin B) with pyrazinoic acid.

The title 1:1 salt, CHNO ·CHNO (systematic name: 4-carb-oxy-anilinium pyrazine-2-carboxyl-ate), was synthesized successfully by slow evaporation of a saturated solution from water-ethanol (1:1 /) mixture and characterized by X-ray diffraction (SCXRD, PXRD) and calorimetry (DSC). The crystal structure of the salt was solved and refined at 150 and 293 K. The salt crystallizes with one mol-ecule of 4-amino-benzoic acid (PABA) and one mol-ecule of pyrazinoic acid (POA) in the asymmetric unit.

Lanthanum-silicate-substituted apatite synthesized by fast mechanochemical method: Characterization of powders and biocoatings produced by micro-arc oxidation.

Lanthanum-silicate substituted apatite with equal concentrations of the substituents in the range of 0.2-6.0 mol were produced by a fast method - mechanochemical synthesis.

New Ablation-Resistant Material Candidate for Hypersonic Applications: Synthesis, Composition, and Oxidation Resistance of HfIr-Based Solid Solution.

The peculiarities of the solid-state interaction in the HfC-Ir system have been studied within the 1000-1600 °C temperature range using a set of modern analytical techniques. It was stated that the interaction of HfC with iridium becomes noticeable at temperatures as low as 1000-1100 °C and results in the formation of HfIr-based substitutional solid solution. The homogeneity range of the HfIr phase was evaluated and refined as HfIr-HfIr.

The effect of amino acid backbone length on molecular packing: crystalline tartrates of glycine, β-alanine, γ-aminobutyric acid (GABA) and DL-α-aminobutyric acid (AABA).

We report a novel 1:1 cocrystal of β-alanine with DL-tartaric acid, CHNO·CHO, (II), and three new molecular salts of DL-tartaric acid with β-alanine {3-azaniumylpropanoic acid-3-azaniumylpropanoate DL-tartaric acid-DL-tartrate, [H(CHNO)]·[H(CHO)], (III)}, γ-aminobutyric acid [3-carboxypropanaminium DL-tartrate, CHNO·CHO, (IV)] and DL-α-aminobutyric acid {DL-2-azaniumylbutanoic acid-DL-2-azaniumylbutanoate DL-tartaric acid-DL-tartrate, [H(CHNO)]·[H(CHO)], (V)}. The crystal structures of binary crystals of DL-tartaric acid with glycine, (I), β-alanine, (II) and (III), GABA, (IV), and DL-AABA, (V), have similar molecular packing and crystallographic motifs. The shortest amino acid (i.

Spin Selectivity in Chiral Linked Systems.

This work has shown spin selectivity in electron transfer (ET) of diastereomers of (R,S)-naproxen-(S)-N-methylpyrrolidine and (R,S)-naproxen-(S)-tryptophan dyads. Photoinduced ET in these dyads is interesting because of the still unexplained phenomenon of stereoselectivity in the drug activity of enantiomers. The chemically induced dynamic nuclear polarization (CIDNP) enhancement coefficients of (R,S)-diastereomers are double those of the (S,S)-analogue.

Crystal structure and proton conductivity of a new Cs(HPO)(HPO)·2HO phase in the caesium di- and monohydrogen orthophosphate system.

The MH(AO) acid salts (M = Cs, Rb, K, Na, Li, NH; A = S, Se, As, P) exhibit ferroelectric properties. The solid acids have low conductivity values and are of interest with regard to their thermal properties and proton conductivity. The crystal structure of caesium dihydrogen orthophosphate monohydrogen orthophosphate dihydrate, Cs(HPO)·2HO, has been solved.

Challenges of Mechanochemistry: Is In Situ Real-Time Quantitative Phase Analysis Always Reliable? A Case Study of Organic Salt Formation.

Mechanochemical methods offer unprecedented academic and industrial opportunities for solvent-free synthesis of novel materials. The need to study mechanochemical mechanisms is growing, and has led to the development of real-time in situ X-ray powder diffraction techniques (RI-XRPD). However, despite the power of RI-XRPD methods, there remain immense challenges.

Quantification and modeling of nanomechanical properties of chlorpropamide α, β, and γ conformational polymorphs.

The nanomechanical properties of the α-, β-, and γ- conformational polymorphs of chlorpropamide were determined by the dynamic contact module continuous stiffness measurement at nanoindenter. The mechanical anisotropy of the α-polymorph was confirmed by indenting different faces, and its deformational behavior was assigned as ductile. Based on the nanoindentation results, the β and γ forms are moderately hard with plastic flow at contact points.

Large porous particles for respiratory drug delivery. Glycine-based formulations.

Large porous particles are becoming increasingly popular as carriers for pulmonary drug delivery with both local and systemic applications. These particles have high geometric diameters (5-30μm) but low bulk density (~0.1g/cm or less) such that the aerodynamic diameter remains low (1-5μm).

Solid-state NMR and computational insights into the crystal structure of silicocarnotite-based bioceramic materials synthesized mechanochemically.

In this work, we report the results of a detailed structural study of a promising bioceramic material silicocarnotite Ca(PO)SiO (SC) synthesized from mechanochemically treated nanosized silicon-substituted hydroxyapatite by annealing at 1000°C. This novel synthetic approach represents an attractive and efficient route towards large-scale manufacturing of the silicocarnotite-based bioceramics. A combination of solid-state nuclear magnetic resonance (NMR), powder X-ray crystallography and density function theory (DFT) calculations has been implemented to characterize the phase composition of the prepared composite materials and to gain insight into the crystal structure of silicocarnotite.

New 1:1 and 2:1 salts in the `DL-norvaline-maleic acid' system as an example of assembling various crystal structures from similar supramolecular building blocks.

Molecular salts and cocrystals of amino acids have potential applications as molecular materials with nonlinear optical, ferroelectric, piezoelectric, and other various target physical properties. The wide choice of amino acids and coformers makes it possible to design various crystal structures. The amino acid-maleic acid system provides a perfect example of a rich variety of crystal structures with different stoichiometries, symmetries and packing motifs built from the molecular building blocks, which are either exactly the same, or differ merely by protonation or as optical isomers.

Hypervalency in Organic Crystals: A Case Study of the Oxicam Sulfonamide Group.

The theoretical charge density of the active pharmaceutical ingredient piroxicam (PXM) was evaluated through density functional theory with a localized basis set. To understand the electronic nature of the sulfur atom within the sulfonamide group, a highly ubiquitous functional group in pharmaceutical molecules, a theoretical charge density study was performed on PXM within the framework of Bader theory. Focus is on developing a topological description of the sulfur atom and its bonds within the sulfonamide group.

Crystal structure of a 2:1 co-crystal of meloxicam with acetyl-endi-carb-oxy-lic acid.

The pharmaceutical 2:1 co-crystal of meloxicam [MXM; systematic name: 4-hy-droxy-2-methyl--(5-methyl-thia-zol-2-yl)-2-1,2-benzo-thia-zine-3-carboxamide 1,1-dioxide] with acetyl-enedi-carb-oxy-lic acid (ACA; systematic name: but-2-ynedioic acid), crystallizes with one MXM mol-ecule and half an ACA mol-ecule in the asymmetric unit, CHNOS·0.5CHO. The mid-point of the triple bond of ACA is located on an inversion centre.

Relation between oxygen stoichiometry and thermodynamic properties and the electronic structure of nonstoichiometric perovskite LaSrCoO.

Continuous phase diagram 3 - δ - log pO - T of the nonstoichiometric perovskite LaSrCoO was obtained in a gas flow reactor by means of the quasi-equilibrium oxygen release technique. The thermodynamic properties of oxides were determined as a function of oxygen nonstoichiometry. Within the framework of the itinerant electron model, the dependence of the oxide nonstoichiometry on the oxygen activity was related to the density of electronic states near the Fermi level.

Supramolecular Complex of Ibuprofen with Larch Polysaccharide Arabinogalactan: Studies on Bioavailability and Pharmacokinetics.

Background And Objectives: In the present work, pharmacological and pharmacokinetic properties of the supramolecular complex of non-steroid anti-inflammatory drug ibuprofen (IBU) with natural polysaccharide arabinogalactan (AG) were studied. The main goals of such complexation were the increase of ibuprofen's bioavailability and decrease its effective dose after oral administration.

Methods: The complex with mass ratio as IBU:AG 1:10 was obtained by mechanochemical synthesis and characterized by water solubility, electron microscopy, differential scanning calorimetry, X-ray powder diffraction analysis and H-nuclear magnetic resonance spectroscopy.

Ice Recrystallization in a Solution of a Cryoprotector and Its Inhibition by a Protein: Synchrotron X-Ray Diffraction Study.

Ice formation and recrystallization is a key phenomenon in freezing and freeze-drying of pharmaceuticals and biopharmaceuticals. In this investigation, high-resolution synchrotron X-ray diffraction is used to quantify the extent of disorder of ice crystals in binary aqueous solutions of a cryoprotectant (sorbitol) and a protein, bovine serum albumin. Ice crystals in more dilute (10 wt%) solutions have lower level of microstrain and larger crystal domain size than these in more concentrated (40 wt%) solutions.

Formation of Aluminum Particles with Shell Morphology during Pressureless Spark Plasma Sintering of Fe-Al Mixtures: Current-Related or Kirkendall Effect?

A need to deeper understand the influence of electric current on the structure and properties of metallic materials consolidated by Spark Plasma Sintering (SPS) stimulates research on inter-particle interactions, bonding and necking processes in low-pressure or pressureless conditions as favoring technique-specific local effects when electric current passes through the underdeveloped inter-particle contacts. Until now, inter-particle interactions during pressureless SPS have been studied mainly for particles of the same material. In this work, we focused on the interactions between particles of dissimilar materials in mixtures of micrometer-sized Fe and Al powders forming porous compacts during pressureless SPS at 500-650 °C.

Structure-forming units of amino acid maleates. Case study of L-valinium hydrogen maleate.

A new salt of L-valinium hydrogen maleate was used as an example to study structure-forming units in amino acid maleates. This compound was crystallized, its structure solved from single-crystal X-ray diffraction data, and the phase purity of the bulk powder sample confirmed by X-ray powder diffraction and FT-IR spectra. The stability of the new salt was analyzed using density functional theory and PIXEL calculations with focus on the C(2)2(12) structure-forming crystallographic motif.

Supramolecular architecture of betulin diacetate complexes with arabinogalactan from Larix sibirica.

Supramolecular ensembles of arabinogalactan (AG) and its complexes with betulin diacetate (BDA) were studied in water and dimethyl sulfoxide (DMSO) using ablation, induced by submillimeter radiation from the free electron laser. Solutions of 1wt% AG resulted in formation of aerosol particles with a maximum size of 60-70nm. In contrast, with DMSO as the solvent, the majority of particles were significantly smaller.

A new active Li-Mn-O compound for high energy density Li-ion batteries.

The search for new materials that could improve the energy density of Li-ion batteries is one of today's most challenging issues. Many families of transition metal oxides as well as transition metal polyanionic frameworks have been proposed during the past twenty years. Among them, manganese oxides, such as the LiMn2O4 spinel or the overlithiated oxide Li[Li1/3Mn2/3]O2, have been intensively studied owing to the low toxicity of manganese-based materials and the high redox potential of the Mn(3+)/Mn(4+) couple.

Isoenergetic Polymorphism: The Puzzle of Tolazamide as a Case Study.

In the present case study of tolazamide we illustrate how many seemingly contradictory results that have been obtained from experimental observations and theoretical calculations can finally start forming a consistent picture: a "puzzle put together". For many years, tolazamide was considered to have no polymorphs. This made this drug substance unique among the large family of sulfonylureas, which was known to be significantly more prone to polymorphism than many other organic compounds.