Synthesis of cyclic carbonates from epoxides: Use of reticular oxygen of Al2O3 or Al2O3-supported CeOx for the selective epoxidation of propene

Reticular oxygen of Al₂O₃ or CeO_x supported on Al₂O₃ was used for the epoxidation of propene without any double bond cleavage. In batch reaction, Al₂O₃ alone was able to convert propene into propene oxide (PO) with 100% selectivity and 2% conversion of propene with a close to 3:1 ratio with respect to the number of Al(III) reduced to elemental Al. When Ce₂O₃/Al₂O₃ or CeO₂/Al₂O₃ was used, Al remained in its +3 oxidation state, while the Ce oxide was the oxidant as demonstrated by XPS analyses. CeO_x/Al₂O₃ was more active (propene conversion yield of 4–5%) but the selectivity was lower (70%) as PO was isomerized into acetone and propionaldehyde.

Interestingly the use of reticular oxygen very much improves the selectivity with respect to the use of pure O₂. In fact, while propene was more efficiently oxidized (10%) with O₂ in presence of Al₂O₃ or CeO_x/Al₂O₃, the selectivity was as low as 40% because C1 and C2 products were formed. However, the use of reticular oxygen represents a selective two-step technique for the use of molecular oxygen as oxidant of propene. The used oxides can be re-oxidized and the whole process can be further improved towards higher yields.

PO is quantitatively converted into propene carbonate by reaction with CO₂ in presence of Nb₂O₅.     

<Emphasis Type="Italic">X</Emphasis>- and <Emphasis Type="Italic">Y</Emphasis>-invariants of partial differential operators in the plane

In the paper, a classical computer algebra problem—symbolic solution of differential equations—is considered. Particularly, widely used Darboux theorems on transformation of hyperbolic operators in the plane are extended to the space of invariants by means of differential substitutions. X- and Y-invariants for such operators are introduced as solutions of some equations written in terms of the Laplace invariants of operator L with respect to gauge transformations. Explicit formulas of transformations of sets of X- and Y-invariants under the Darboux transformations are obtained.     

SYNTACTIC SIMPLIFICATION AND SEMANTIC ENRICHMENT—TRIMMING DEPENDENCY GRAPHS FOR EVENT EXTRACTION

In our approach to event extraction, dependency graphs constitute the fundamental data structure for knowledge capture. Two types of trimming operations pave the way to more effective relation extraction. First, we simplify the syntactic representation structures resulting from parsing by pruning informationally irrelevant lexical material from dependency graphs. Second, we enrich informationally relevant lexical material in the simplified dependency graphs with additional semantic meta data at several layers of conceptual granularity. These two aggregation operations on linguistic representation structures are intended to avoid overfitting of machine learning‐based classifiers which we use for event extraction (besides manually curated dictionaries). Given this methodological framework, the corresponding JReX system developed by the Julie Lab Team from Friedrich‐Schiller‐Universität Jena (Germany) scored on 2nd rank among 24 competing teams for Task 1 in the “BioNLP’09 Shared Task on Event Extraction,” with 45.8% recall, 47.5% precision and 46.7% F1‐score on all 3,182 events. In more recent experiments, based on slight modifications of JReX and using the same data sets, we were able to achieve 45.9% recall, 57.7% precision, and 51.1% F1‐score.     

Tailoring mesoporous-silica nanoparticles for robust immobilization of lipase and biocatalysis

The rational design of nano-carriers is critical for modem enzyme immobilization for advanced biocatalysis.Herein,we report the synthesis of octadecylalkylmodified mesoporous-silica nanoparticles (C18-MSNs) with a high C18 content (～19 wt.％) and tunable pore sizes (1.6-13 nm).It is demonstrated that the increased hydrophobic content and a tailored pore size (slightly larger than the size of lipase) are responsible for the high performance of immobilized lipase.The optimized C18-MSNs exhibit a loading capacity of 711 mg/g and a specific activity 5.23 times higher than that of the free enzyme.Additionally,93％ of the initial activity is retained after reuse five times,which is better than the best performance reported to date.Our findings pave the way for the robust immobilization of lipase for biocatalytic applications.     

Cavitation technologies for dispergation and homogenization

The results of tests carried out in industrial conditions are presented. They allow one to propose cavitation technologies of dispergation and homogenization for fabricating emulsions and suspensions under the action of ultrasonic, hydrodynamic, and hydroacoustic cavitation. The dispergation regimes were found for materials with various physicochemical properties, including viscous media (natural juices with pulp) and materials with a lamella structure (bentonite). Cavitation effects intensify dispergation processes and allow one to produce materials with submicronic dimension of the particles; this considerably increases the sedimentation period of the suspensions.     

Ferroelectric properties of LC systems including chiral dopants with different molecular structure

Abstract— New ferroelectric liquid crystals (FLCs) on the basis of the eutectic mixture of phenylbenzoate derivatives including chiral components (CCs) with a different number and position of carbonyl groups in their molecular core have been investigated. The ferroelectric characteristics such as the spontaneous polarization, smectic tilt angle, rotational viscosity, and repolarization time as well as their concentration dependences are analyzed. On the basis of the previous and obtained results, the influence of peculiarities of the molecular structure of CCs on mentioned properties of FLCs are generalized.     

Additive manufacturing of polymer-derived ceramic matrix composites

This study presents a fabrication method and identifies processing bounds for additively manufacturing (AM) ceramic matrix composites (CMCs), comprising a silicon oxycarbide (SiOC) ceramic matrix. A digital light projection printer was used to photopolymerize a siloxane-based preceramic resin containing inert ceramic reinforcement. A subsequent pyrolysis converted the preceramic polymer to SiOC. Particle reinforcements of 0 to 40% by volume in the green state were uniformly dispersed in the printed samples to study their effects on pyrolysis mass loss and shrinkage, and CMC notch sensitivity and strength. Both particle and whisker reinforcements toughened the glassy SiOC matrix (1 MPa m^1/2), reaching values >3 MPa m^1/2. Bending strengths of >300 MPa (>150 MPa (g cm⁻³)⁻¹) and a Weibull modulus of 10 were measured on AM samples without surface finish. We identified two pore formation mechanisms that placed processing bounds on sample size and reinforcement volume fraction. Methods for increasing these bounds are discussed. With properties commensurate to traditionally processed technical ceramics, the presented process allows for free-form fabrication of high-performance AM CMC components.     

Initial anisotropy in demineralized bovine cortical bone in compressive cyclic loading–unloading

The mechanical properties of demineralized bovine cortical femur bone were investigated by cyclic loading–unloading compression in three anatomical directions (longitudinal, radial, transverse) within the physiological strain range. The loading responses in the radial and transverse directions were nearly linear up to 2% strain, while the response in longitudinal direction was strongly non-linear in that range. The unloading responses were non-linear for each anatomical direction, giving rise to overall loading–unloading hysteresis and cyclic dissipation of energy. The mechanical properties were observed to be anisotropic: the radial direction was found to be the most energy dissipative, while the longitudinal direction appeared to be the stiffest bone direction. The cyclic loading mostly affects the bone stiffness in the radial and transverse directions, while the longitudinal direction was found to be the least affected. These anisotropic properties can be attributed to the differences in collagen fibers alignment and different microstructural architecture in three different anatomical bone directions.     

Effects of Aqueous Dispersions of C60, C70 and Gd@C82 Fullerenes on Genes Involved in Oxidative Stress and Anti-Inflammatory Pathways

Background: Fullerenes and metallofullerenes can be considered promising nanopharmaceuticals themselves and as a basis for chemical modification. As reactive oxygen species homeostasis plays a vital role in cells, the study of their effect on genes involved in oxidative stress and anti-inflammatory responses are of particular importance. Methods: Human fetal lung fibroblasts were incubated with aqueous dispersions of C₆₀, C₇₀, and Gd@C₈₂ in concentrations of 5 nM and 1.5 µM for 1, 3, 24, and 72 h. Cell viability, intracellular ROS, NOX4, NFκB, PRAR-γ, NRF2, heme oxygenase 1, and NAD(P)H quinone dehydrogenase 1 expression have been studied. Results & conclusion: The aqueous dispersions of C₆₀, C₇₀, and Gd@C₈₂ fullerenes are active participants in reactive oxygen species (ROS) homeostasis. Low and high concentrations of aqueous fullerene dispersions (AFD) have similar effects. C₇₀ was the most inert substance, C₆₀ was the most active substance. All AFDs have both “prooxidant” and “antioxidant” effects but with a different balance. Gd@C₈₂ was a substance with more pronounced antioxidant and anti-inflammatory properties, while C₇₀ had more pronounced “prooxidant” properties.