Functional MRI using super-resolved spatiotemporal encoding

Recently, new ultrafast imaging sequences such as rapid acquisition by sequential excitation and refocusing (RASER) and hybrid spatiotemporal encoding (SPEN) magnetic resonance imaging (MRI) have been proposed, in which the phase encoding of conventional echo planar imaging (EPI) is replaced with a SPEN. In contrast to EPI, SPEN provides significantly higher immunity to frequency heterogeneities including those caused by B₀ inhomogeneities and chemical shift offsets. Utilizing the inherent robustness of SPEN, it was previously shown that RASER can be used to successfully perform functional MRI (fMRI) experiments in the orbitofrontal cortex — a task which is challenging using EPI due to strong magnetic susceptibility variation near the air-filled sinuses. Despite this superior performance, systematic analyses have shown that, in its initial implementation, the use of SPEN was penalized by lower signal-to-noise ratio (SNR) and higher radiofrequency power deposition as compared to EPI-based methods. A recently developed reconstruction algorithm based on super-resolution principles is able to alleviate both of these shortcomings; the use of this algorithm is hereby explored within an fMRI context. Specifically, a series of fMRI measurements on the human visual cortex confirmed that the super-resolution algorithm retains the statistical significance of the blood oxygenation level dependent (BOLD) response, while significantly reducing the power deposition associated with SPEN and restoring the SNR to levels that are comparable with those of EPI.     

Hydration of humic and fulvic acids studied by DSC

Qualitative and quantitative aspects of hydration of four humic acids (HA) and three fulvic acids (FA) originating from different sources were investigated. DSC experiments at subambient temperatures were carried out in order to monitor differences in ice behavior originating from freezable water surrounding humic molecules. It was found that kinetic effects play a significant role in hydration processes of both HA and FA. In fact, the hydration took part over 21?days which was detected as a progressive decrease in ice melting enthalpy. Simultaneously, the peak shapes and positions changed indicating structural changes in the physical structure of the humic substances. In case of FA, the dependency of melting enthalpy on water concentration showed a linear trend resembling a complete hydration previously observed for water-soluble hydrophilic polymers. In contrast, the melting enthalpy of some HA increased in a step-like way with increasing water content, suggesting preservation of original hydrophobic scaffold during the hydration. The differences between the rather young FA and the rather old HA lead to the conclusion that water can play a significant role in processes of humification. We assume that separation of hydrophobic and hydrophilic domains and thus increase in nanoscale heterogeneity represents an important physical contribution to the overall humification process. It was also demonstrated that the higher content of oxygen in humic molecules is not the only indicator of higher water holding capacity. Instead the porosity of humic matrix seems to contribute as additional parameter into these processes.     

On-chip fabrication of silver microflower arrays as a catalytic microreactor for allowing in situ SERS monitoring

Silver microflower arrays constructed by upright nanoplates and attached nanoparticles were fabricated inside a microfluidic channel, thus a robust catalytic microreactor for allowing in situ SERS monitoring was proposed. On-chip catalytic reduction shows that the silver microflowers have high catalytic activity and SERS enhancement.     

Preparation of quinolinium salts differing in the length of the alkyl side chain

Quaternary quinolinium salts differing in alkyl chain length are members of a widespread group of cationic surfactants. These compounds have numerous applications in various branches of industry and research. In this work, the preparation of quinoline-derived cationic surface active agents differing in the length of the side alkyl chains (from C? to C??) is described. An HPLC method was successfully developed for distinction of all members of the series of prepared long-chain quinolinium derivatives. In conclusion, some possibilities of intended tests or usage have been summarized. In vitro testing using a microdilution broth method showed good activity of a substance with a C12 chain length against Gram-positive cocci and Candida species.     

Hydrogenolysis goes bio: from carbohydrates and sugar alcohols to platform chemicals

In view of the diminishing oil resources and the ongoing climate change, the use of efficient and environmentally benign technologies for the utilization of renewable resources has become indispensible. Therein, hydrogenolysis reactions offer a promising possibility for future biorefinery concepts. These reactions result in the cleavage of C-C and C-O bonds by hydrogen and allow direct access to valuable platform chemicals already integrated in today's value chains. Thus, hydrogenolysis bears the potential to bridge currently available technologies and future biomass-based refinery concepts. This Review highlights past and present developments in this field, with special emphasis on the direct utilization of cellulosic feedstocks.     

Detailed insight into the hydrogen bonding interactions in acetone-methanol mixtures. A molecular dynamics simulation and Voronoi polyhedra analysis study

Voronoi polyhedra (VP) analysis of mixtures of acetone and methanol is reported on the basis of molecular dynamics computer simulations, performed at 300 K and 1 bar. The composition of the systems investigated covers the entire range from neat acetone to neat methanol. Distribution of the volume, reciprocal volume and asphericity parameter of the VP as well as that of the area of the individual VP faces and of the radius of the empty voids located between the molecules are calculated. To investigate the tendency of the like molecules to self-associate the analyses are repeated by disregarding one of the two components. The self-aggregates of the disregarded component thus turn into large empty voids, which are easily detectable in VP analysis. The obtained results reveal that both molecules show self-association, but this behavior is considerably stronger among the acetone than among the methanol molecules. The strongest self-association of the acetone and methanol molecules is found in their mole fraction ranges of 02-0.5 and 0.5-0.6, respectively. The caging effect around the methanol molecules is found to be stronger than around acetones. Finally, the local environment of the acetone molecules turns out to be more spherical than that of the methanols, not only in the respective neat liquids, but also in their mixtures.     

On-Line Chain Partitions of Orders: A Survey

On-line chain partition is a two-player game between Spoiler and Algorithm. Spoiler presents, point by point, a partially ordered set. Algorithm assigns incoming points (immediately and irrevocably) to the chains which constitute a chain partition of the order. The value of the game for orders of width w is a minimum number val(w) such that Algorithm has a strategy using at most val(w) chains on orders of width at most w. There are many recent results about variants of the general on-line chain partition problem. With this survey we attempt to give an overview over the state of the art in this field. As particularly interesting aspects of the article we see:

Structure of praseodymium and neodymium gallate glasses

The rare-earth gallate glasses R₄Ga₆O₁₅, where R denotes Pr or Nd, were prepared using an aerodynamic levitator and laser heating system. The structure was studied by applying the method of isomorphic substitution in neutron diffraction which allows for an identification of the gallium and rare-earth coordination environments. The results give a mean Ga-O coordination number of 4.2(1) at a distance of 1.85(2) Å and a mean R-O coordination number of 7.4(2) at a mean distance of 2.38(2) Å. The experimental results are consistent with a glass network built from GaO₄ tetrahedra and with the presence of GaO₆ octahedra at the 10(5)% level.     

Nitrosyl iron complexes--synthesis, structure and biology

Nitrosyl complexes of iron are formed in living species in the presence of nitric oxide. They are considered a form in which NO can be stored and stabilized within a living cell. Upon entering a topic in bioinorganic chemistry the researcher faces a wide spectrum of issues concerning synthetic methods, the structure and chemical properties of the complex on the one hand, and its biological implications on the other. The aim of this review is to present the newest knowledge on nitrosyl iron complexes, summarizing the issues that are important for understanding the nature of nitrosyl iron complexes, their possible interactions, behavior in vitro and in vivo, handling of the preparations etc. in response to the growing interest in these compounds. Herein we focus mostly on the dinitrosyl iron complexes (DNICs) due to their prevailing occurrence in NO-treated biological samples. This article reviews recent knowledge on the structure, chemical properties and biological action of DNICs and some mononitrosyls of heme proteins. Synthetic methods are also briefly reviewed.     

Solvent response of polymers for micromachine manipulation

A novel solvent responsive polymer micromachine has been successfully fabricated by two-photon photopolymerization (TPP) of methacrylate-based photoresists. The moving part of the micromachine could be easily driven by interfacial solvent polarity induced swelling and shrinking of the photopolymer networks. Furthermore, the driving performance of the micromachine could be precisely modulated by varying the laser scanning step length during fabrication.