Novel synthesis of highly ordered mesoporous Fe2O3/SiO2 nanocomposites for a room temperature VOC sensor

The controlled synthesis of mesoporous silica and metal oxide nanocomposites with a highly ordered porous structure and large specific surface area for specific applications has been an attractive topic in the field of porous materials. Herein, we introduce a novel method for the fabrication of highly ordered mesoporous structured and large specific surface area Fe₂O₃/SiO₂ nanocomposites, and consider their application in room temperature gas sensors. The mesoporous Fe₂O₃/SiO₂ nanocomposites were synthesised by a two-step method, which combines the hydrothermal growth of Fe₂O₃ nanoparticles and the microemulsion phase of Brij 56 (C₁₆EO₁₀) surfactant as templates in instantly direct-templating synthesis. This synthesis method enables the fabrication of mesoporous Fe₂O₃/SiO₂ nanocomposites without distortion of the ordered porous structure after calcination at high temperature. The synthesised materials were found to be efficient in a room temperature VOC sensor application, with good recovery.     

Determination of melagatran in rabbit plasma by high-performance liquid chromatography with automated column switching

Melagatran is an active thrombin inhibitor showing oral and parenteral bioavailability for antithrombotic therapy. A simple and convenient liquid chromatographic method has been developed and applied to the analysis of melagatran in rabbit plasma. The clean-up and separation of the sample solutions were performed by automated on-line column switching HPLC. The method validation shows the suitability of the column switching liquid chromatographic system for the quantitation of melagatran in biological fluids.     

On local cohomology and Hilbert function of powers of ideals

Let I be a homogeneous ideal in a polynomial ring R=K[x₁,,x_m], where K is an infinite field. In this article we investigate the asymptotic behaviour of the a_i-invariants and the regularity index of the ring R/Iⁿ when n»0.Both authors were supported by the Academy of Finland, Project 48556. The first named author was also supported in part by the National Basic Research Program (Vietnam)Mathematics Subject Classification (2000):13D40, 13D45     

L-equivalence of systems of functions in many-valued logics

Translated from Algebra i Logika, Vol. 27, No. 1, pp. 37–47, January–February, 1988.     

A Tunable picosecond dye laser based on cavity quenching and spectro-temporal selection

The development of a tunable picosecond dye laser, based on quenching cavity (QC) in an oscillator and spectro-temporal selection (STS) before amplification, is described. A theoretical model was constructed for the calculation of temporal and spectral evolutions of dye laser emission using a series of equations representing population inversions. The pulsewidth, linewidth, and pulse energy, obtained experimentally, were 90 ps, 0.2 nm, and 10 J, respectively. The tunable range, in which a single picosecond pulse can be obtained, was expanded from 4 to 20 nm for a single dye solution by applying QC to STS. Thus, the spectral region was covered from 320 to 360 nm using two laser dyes, i.e., BM-terphenyl and BBQ. Experimental data obtained using the instrument were in reasonably good agreement with values predicted from theory. PACS 42.55.Mv; 42.60.By     

Magnetism due to oxygen vacancies and/or defects in undoped semiconducting and insulating oxide thin films

Room temperature ferromagnetism was observed in HfO₂, TiO₂, and In₂O₃ films grown on yttrium-stabilized zirconia, LaAlO₃, and MgO substrates, respectively. While the magnetic moment is rather modest in the case of In₂O₃ films, it is very large in the other two cases. Thin film form, which might create necessary defects and/or oxygen vacancies, must be the main reason for undoped semiconducting and insulating oxides to become ferromagnetic. From the results, a serious question arises if a transition-metal doping indeed plays any essential role in producing ferromagnetism (FM) in non-magnetic oxides.     

From Open‐Shell Singlet Diradicaloid to Closed‐Shell Global Antiaromatic Macrocycles

A dithieno[a,h]‐s‐indacene‐ (DTI‐) based diradicaloid DTI‐2Br was synthesized and its open‐shell singlet diradical character was validated by magnetic measurements. On the other hand, its macrocyclic trimer DTI‐MC3 and tetramer DTI‐MC4 turned out to be closed‐shell compounds with global antiaromaticity, which was supported by X‐ray crystallographic analysis and NMR spectroscopy, assisted by ACID and 2D‐ICSS calculations. Such change can be explained by a subtle balance between two types of antiferromagnetic spin–spin coupling along the π‐conjugated macrocycles. The dications of DTI‐MC3 and DTI‐MC4 turned out to be open‐shell singlet diradical dications, with a singlet–triplet energy gap of ?2.90 and ?2.60 kcal mol^?1, respectively. At the same time, they are both global aromatic. Our studies show that intramolecular spin–spin interactions play important roles on electronic properties of π‐conjugated macrocycles.     

Unexpected Strong Luminescence of Polysiloxanes Containing Carbazolyl and C60 Moeities as Side Chains

Two types of polysiloxanes,which contain both C60 moieties and carbazolyl groups in the side chains with a difference in the numbers of the reacting site on C60 molecules,were synthesized and their fluorescent properties were studied to distinguish the role of C60 in the luminescent polymers.Our results demonstrated that when C60 moieties are bonded to the polymers as multisubstituents but not linked to the luminescent moieties directly,the luminescence of the resultant polymers were still very strong instead of quenching,even the substituted degree is only 1.01.