Temperature-dependent crystal structure of the isopropanol clathrate of Dianin's compound

The title compound undergoes two order-disorder transitions between 15 and 299 K, dictated by ordering of the guest molecules in the host cages, and resulting in three related crystal structures. We anticipate behaviour of this kind to be widespread, and speculate that the concept of "the crystal structure" for individual Dianin's clathrates may be elusive.     

Patterning functional materials using channel diffused plasma-etched self-assembled monolayer templates

A simple and cost-effective methodology for large-area micrometer-scale patterning of a wide range of metallic and oxidic functional materials is presented. Self-assembled monolayers (SAM) of alkyl thiols on Au were micropatterned by channel-diffused oxygen plasma etching, a method in which selected areas of SAM were protected from plasma oxidation via a soft lithographic stamp. The patterned SAMs were used as templates for site-selective electrodeposition, electroless deposition and solution-phase deposition of functional materials such as ZnO, Ni, Ag thin films, and ZnO nanowires. The patterned SAMs and functional materials were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), atomic force microscopy (AFM), and tunneling AFM (TUNA).     

Synthesis and anion-exchange reactions of a new anionic clay, α-magnesium hydroxide

A new anionic clay, α-magnesium hydroxide, was synthesized by hydrolysis of magnesium acetate in propylene glycol. The structure of this α-hydroxide is similar to that of hydrotalcites. It consists of positively charged magnesium hydroxide layers arising out of partial protonation of the hydroxyl groups of the [Mg(OH)(2)] layers and loosely held anions in the interlayer region. As expected it ages readily in water to give β-magnesium hydroxide, brucite. While anion-exchange reactions of α-magnesium hydroxide could not be carried out in aqueous medium a number of anion-exchange reactions could be carried out successfully in ethanol medium.     

Trifluoroethanol and 19F magic angle spinning nuclear magnetic resonance as a basic surface hydroxyl reactivity probe for zirconium(IV) hydroxide structures

A novel technique for determining the relative accessibility and reactivity of basic surface hydroxyl sites by reacting various zirconium(IV) hydroxide materials with 2,2,2-trifluoroethanol (TFE) and characterizing the resulting material using (19)F magic angle spinning (MAS) nuclear magnetic resonance (NMR) is presented here. Studied here are three zirconium hydroxide samples, two unperturbed commercial materials, and one commercial material that is crushed by a pellet press. Factors, such as the ratio of bridging/terminal hydroxyls, surface area, and pore size distribution, are examined and found to affect the ability of the zirconium(IV) hydroxide to react with TFE. X-ray diffraction, nitrogen isotherms, and (1)H MAS NMR were used to characterize the unperturbed materials, while thermogravitric analysis with gas chromatography and mass spectrometry along with the (19)F MAS NMR were used to characterize the materials that were reacted with TFE. Zirconium hydroxide materials with a high surface area and a low bridging/terminal hydroxyl ratio were found to react TFE in the greatest amounts.     

Enhancing the discrimination accuracy between metastases, gliomas and meningiomas on brain MRI by volumetric textural features and ensemble pattern recognition methods

Three-dimensional (3D) texture analysis of volumetric brain magnetic resonance (MR) images has been identified as an important indicator for discriminating among different brain pathologies. The purpose of this study was to evaluate the efficiency of 3D textural features using a pattern recognition system in the task of discriminating benign, malignant and metastatic brain tissues on T1 postcontrast MR imaging (MRI) series. The dataset consisted of 67 brain MRI series obtained from patients with verified and untreated intracranial tumors. The pattern recognition system was designed as an ensemble classification scheme employing a support vector machine classifier, specially modified in order to integrate the least squares features transformation logic in its kernel function. The latter, in conjunction with using 3D textural features, enabled boosting up the performance of the system in discriminating metastatic, malignant and benign brain tumors with 77.14%, 89.19% and 93.33% accuracy, respectively. The method was evaluated using an external cross-validation process; thus, results might be considered indicative of the generalization performance of the system to "unseen" cases. The proposed system might be used as an assisting tool for brain tumor characterization on volumetric MRI series.     

Pattern recognition system for the discrimination of multiple sclerosis from cerebral microangiopathy lesions based on texture analysis of magnetic resonance images

In this study, a pattern recognition system has been developed for the discrimination of multiple sclerosis (MS) from cerebral microangiopathy (CM) lesions based on computer-assisted texture analysis of magnetic resonance images. Twenty-three textural features were calculated from MS and CM regions of interest, delineated by experienced radiologists on fluid attenuated inversion recovery images and obtained from 11 patients diagnosed with clinically definite MS and from 18 patients diagnosed with clinically definite CM. The probabilistic neural network classifier was used to construct the proposed pattern recognition system and the generalization of the system to unseen data was evaluated using an external cross validation process. According to the findings of the present study, statistically significant differences exist in the values of the textural features between CM and MS: MS regions were darker, of higher contrast, less homogeneous and rougher as compared to CM.     

Improved MALDI-TOF imaging yields increased protein signals at high molecular mass

Matrix assisted laser desorption ionization (MALDI) mass spectrum images are created from an array of mass spectra collected over a tissue surface. We have increased the mass range of proteins that can be detected in tissue sections from kidneys, heart, lung and brain of different rodent species by a modification of the sandwich technique, which involves co-crystallizing matrix with analyte. A tissue section is placed upon a drop of sinapinic acid matrix dissolved in 90% ethanol and 0.5% Triton X-100. Once the matrix has dried, a seed layer of sinapinic crystals is added as a dispersion in xylene. Additional layers of sinapinic acid are added as solutions in 90% ethanol followed by 50% acetonitrile. Numerous peaks with signal to noise ratio of four or greater are observed between 25 kDa to 50 kDa. This represents approximately 10 times as many peaks as are detected using traditional matrix spotting and spraying.     

Leaf anatomy affects the extraction of photosynthetic pigments by DMSO

Dimethylsulfoxide (DMSO) is a widely used solvent for the extraction of chlorophylls (Chls) from leaves of higher plants. The method is preferred because the time-consuming steps of grinding and centrifuging are not required and the extracts are stable for a long time period. However, the extraction efficiency of this solvent is not comparable among plant species, whereas the particular leaf anatomical characteristics responsible for this unevenness remain unknown. In order to examine the influence of leaf anatomy on the extraction efficiency of DMSO (i.e. the concentration of Chls extracted with DMSO as % of the concentration of Chls extracted with 80% acetone), leaves of 19 plant species with different anatomical characteristics were incubated for 40min in DMSO at 65 degrees C. Under these conditions, heterobaric leaves, which are characterized by the occurrence of bundle sheath extensions in the mesophyll, showed lower extraction efficiency of DMSO compared to homobaric leaves and conifer needles. Microscopical observations of DMSO incubated leaf tissues showed that bundle sheath extensions behave as anatomical barriers which prevent the diffusion of DMSO within heterobaric leaves, even after prolonged incubation with the solvent. The effect was stronger in heterobaric leaves possessing thick bundle sheath extensions. The extraction efficiency of DMSO in these leaves was improved by vacuum infiltration of the samples in the presence of warm (65 degrees C) solvent.