Boron-chelate assisted synthesis of new bipyrazole derivatives

1. Download high-res image (99KB)
2. Download full-size image

     

High‐Pressure Synthesis of a Nitrogen‐Rich Inclusion Compound ReN8⋅x N2 with Conjugated Polymeric Nitrogen Chains

A nitrogen‐rich compound, ReN₈?x N₂, was synthesized by a direct reaction between rhenium and nitrogen at high pressure and high temperature in a laser‐heated diamond anvil cell. Single‐crystal X‐ray diffraction revealed that the crystal structure, which is based on the ReN₈ framework, has rectangular‐shaped channels that accommodate nitrogen molecules. Thus, despite a very high synthesis pressure, exceeding 100 GPa, ReN₈?x N₂ is an inclusion compound. The amount of trapped nitrogen (x) depends on the synthesis conditions. The polydiazenediyl chains [?N=N?]_∞ that constitute the framework have not been previously observed in any compound. Ab initio calculations on ReN₈?x N₂ provide strong support for the experimental results and conclusions.     

SMART: A data reporting standard for mass spectrometry imaging By Ying Xi,Alexandria L. Sohn,Alena N. Joignant,Stephanie M. Cologna,Boone M. Prentice and David C. Muddiman

Mass spectrometry imaging (MSI) is an important analytical technique that simultaneously reports the spatial location and abundance of detected ions in biological, chemical, clinical, and pharmaceutical studies. As MSI grows in popularity, it has become evident that data reporting varies among different research groups and between techniques. The lack of consistency in data reporting inherently creates additional challenges in comparing intra- and inter-laboratory MSI data. In this tutorial, we propose a unified data reporting system, SMART, based on the common features shared between techniques. While there are limitations to any reporting system, SMART was decided upon after significant discussion to more easily understand and benchmark MSI data. SMART is not intended to be comprehensive but rather capture essential baseline information for a given MSI study; this could be within a study (e.g., effect of spot size on the measured ion signals) or between two studies (e.g., different MSI platform technologies applied to the same tissue type). This tutorial does not attempt to address the confidence with which annotations are made nor does it deny the importance of other parameters that are not included in the current SMART format. Ultimately, the goal of this tutorial is to discuss the necessity of establishing a uniform reporting system to communicate MSI data in publications and presentations in a simple format to readily interpret the parameters and baseline outcomes of the data.     

Influence of laser photobiomodulation upon connective tissue remodeling during wound healing

The modulation of collagen fibers during experimental skin wound healing was studied in 112 Wistar rats submitted to laser photobiomodulation treatment. A standardized 8mm-diameter wound was made on the dorsal skin of all animals. In half of them, 0.2ml of a silica suspension was injected along the border of the wound in order to enhance collagen deposition and facilitate observation. The others received saline as vehicle. The treatment was carried out by means of laser rays from an aluminum-gallium arsenide diode semiconductor with 9mW applied every other day (total dose=4J/cm(2)) on the borders of the wound. Tissue sections obtained from four experimental groups representing sham-irradiated animals, laser, silica and the association of both, were studied after 3, 7, 10, 15, 20, 30 and 60 days from the laser application. The wounded skin area was surgically removed and submitted to histological, immunohistochemical, ultrastructural, and immunofluorescent studies. Besides the degree and arrangement of collagen fibers and of their isotypes, the degree of edema, the presence of several cell types especially pericytes and myofibroblasts, were described and measured. The observation of Sirius-red stained slides under polarized microscopy revealed to be of great help during the morphological analysis of the collagen tissue dynamic changes. It was demonstrated that laser application was responsible for edema regression and a diminution in the number of inflammatory cells (p<0.05). An evident increase in the number of actin-positive cells was observed in the laser-treated wounds. Collagen deposition was less than expected in silica-treated wounds, and laser treatment contributed to its better differentiation and modulation in all irradiated groups. Thus, laser photobiomodulation was able to induce several modifications during the cutaneous healing process, especially in favoring newly-formed collagen fibers to be better organized and compactedly disposed.     

Density functional model studies of uranyl adsorption on (001) surfaces of kaolinite

The adsorption of uranyl on two types of neutral (001) surfaces of kaolinite, tetrahedral Si(t) and octahedral Al(o), was studied by means of density functional periodic slab model calculations. Various types of model surface complexes, adsorbed at different sites, were optimized and adsorption energies were estimated. As expected, the Si(t) surface was found to be less reactive than the Al(o) surface. At the neutral Al(o) surface, only adsorption at protonated sites is calculated to be exothermic for inner- as well as outer-sphere adsorption complexes, with monodentate coordination being preferred. Adsorption energies as well as structural features of the adsorption complexes are mainly determined by the number of deprotonated surface hydroxyl groups involved. Outer-sphere complexes on both surfaces exhibit a shorter U-O bond to the aqua ligand of uranyl that is in direct contact with the surface than to the other aqua ligands. This splitting of the shell of equatorial U-O bonds is at variance with common expectations for outer-sphere surface complexes of uranyl.     

Biocompatible Size‐Defined Dendrimer–Albumin Binding Protein Hybrid Materials as a Versatile Platform for Biomedical Applications

For the design of a biohybrid structure as a ligand‐tailored drug delivery system (DDS), it is highly sophisticated to fabricate a DDS based on smoothly controllable conjugation steps. This article reports on the synthesis and the characterization of biohybrid conjugates based on noncovalent conjugation between a multivalent biotinylated and PEGylated poly(amido amine) (PAMAM) dendrimer and a tetrameric streptavidin‐small protein binding scaffold. This protein binding scaffold (SA‐ABDwt) possesses nM affinity toward human serum albumin (HSA). Thus, well‐defined biohybrid structures, finalized by binding of one or two HSA molecules, are available at each conjugation step in a controlled molar ratio. Overall, these biohybrid assemblies can be used for (i) a controlled modification of dendrimers with the HSA molecules to increase their blood‐circulation half‐life and passive accumulation in tumor; (ii) rendering dendrimers a specific affinity to various ligands based on mutated ABD domain, thus replacing tedious dendrimer–antibody covalent coupling and purification procedures.

     

Inhibition of Calcium Oxalate Monohydrate Crystal Growth in High and Low Ionic Strength Solutions

The effect of additives on the kinetics of growth of calcium oxalate monohydrate crystals has been studied. Conductivity and potentiometry measurements have been compared. Growth rates were calculated from precipitate curves by a cubic spline method. An approach consisting on the calculation of rate constants and orders of reaction from logarithmic plots of growth rate versus supersaturation has been followed to study crystal growth kinetics. This method revealed that the presence of additives is causing not only a decrease on the rate constant but an increase on the order of reaction as well. The effect of additives (EDTA, citrate and phytate) was considerably weaker in high ionic strength media. Phytate produced a complete blockage of crystal growth in concentrations as low as 2 × 10^—6 mole/L in both methods.     

Separation of PCR-ready DNA from dairy products using magnetic hydrophilic microspheres and poly(ethylene glycol)-NaCl water solutions

Carboxyl group-containing magnetic nonporous poly(2-hydroxyethyl methacrylate-co-glycidyl methacrylate) (P(HEMA-co-GMA)) and magnetic glass microspheres were used for the isolation of bacterial DNA. P(HEMA-co-GMA) microspheres were prepared by the dispersion polymerization in toluene/2-methylpropan-1-ol mixture in the presence of magnetite nanoparticles obtained by coprecipitation of Fe(II) and Fe(III) salts with ammonium hydroxide. Carboxyl groups were then introduced by oxidation of the microspheres with potassium permanganate. The most extensive DNA recovery was achieved at PEG 6000 concentrations of 12% or 16% and 2 M NaCl. The method proposed was used for bacterial DNA isolation from different dairy products containing Bifidobacterium and Lactobacillus cells. The presence of target DNA and the quality of isolated DNA were checked by polymerase chain reaction (PCR) amplification with specific primers.     

Isolation of polymerase chain reaction-ready bacterial DNA from Lake Baikal sediments by carboxyl-functionalised magnetic polymer microspheres

Carboxyl group-containing magnetic nonporous poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate) (P(HEMA-co-EDMA)) microspheres were used for the isolation of polymerase chain reaction (PCR)-ready DNA from samples of Baikal sediments. DNA was isolated using the phenol extraction method or the Soil DNA Isolation Kit. The occurrence of false-negative results in PCR caused by the presence of extracellular inhibitors in DNA samples was solved using solid phase reversible DNA immobilisation. PCR-ready DNA was reversibly adsorbed to the microspheres in the presence of 8.0% (w/v) poly(ethylene glycol) (PEG 6000) and 2.0M sodium chloride concentrations. The adsorbed DNA was released from the microspheres in a low ionic strength TE buffer. The quality of isolated DNA was checked by PCR amplification.