C18 tetraynoic fatty acids and essential oil composition of Mkilua fragrans

The fatty acids 17,18-dihydroxyoctadeca-9,11,13,15-tetraynoic acid (mkiluaynoic acid A) and 18-hydroxyoctadeca-9,11,13,15-tetraynoic acid (mkiluaynoic acid B), 5,7,3',4'-tetrahydroxyflavanol, 3,4-dihydroxybenzoic acid and a mixture of stearic and oleic acids were isolated from fruits and stem barks of Mkilua fragrans (Annonaceae). Mkiluaynoic acid A exhibited antifungal activity against Candida albicans comparable with that of the standard antifungal agent Ketoconazole. Structural determination was achieved by analysis of spectroscopic data. The flower stalks yielded essential oils that mainly consisted of sesquiterpenoids as revealed by GC-MS analysis, whereby 14 sesquiterpenes and four other compounds were identified.     

Development of a reference material for routine performance monitoring of methods measuring polychorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and dioxin-like polychlorinated biphenyls

Matrix–matched environmental certified reference materials (CRMs) are one of the most useful tools to validate analytical methods, assess analytical laboratory performance and to assist in the resolution of data conflicts between laboratories. This paper describes the development of a lake sediment as a CRM for polychorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (DLPCBs). The presence of DLPCBs in the environment is of increased concern and analytical methods are being developed internationally for monitoring DLPCBs in the environment. This paper also reports the results of an international interlaboratory study involving thirty-five laboratories from seventeen countries, conducted to characterize and validate levels of a sediment reference material for PCDDs, PCDFs and DLPCBs.     

Methyl methacrylate polymerization at samarium(II)-grafted MCM-41

Sm(II)-modified periodic mesoporous silica (PMS), Sm[N(SiHMe₂)₂]₂(THF)_x@MCM-41, was used for the synthesis of Sm(II) alkyl, alkoxide, and indenyl surface species via secondary ligand exchange. The performance of the novel Sm(II)-based organometallic–inorganic hybrid materials as initiators for the graft polymerization of methyl methacrylate (MMA) is reported. All of the Sm(II) hybrid materials including the new PMMA–PMS composites were characterized via N₂ physisorption, elemental analysis, FTIR spectroscopy, and scanning electron microscopy (SEM). The organic–inorganic composites revealed complete pore blockage as well as enrichment and strong adhesion of the polymer at the exterior of the porous silica material.     

Classification of malignant gliomas by infrared spectroscopic imaging and linear discriminant analysis

Infrared (IR) spectroscopy provides a sensitive molecular fingerprint for tissue without external markers. Supervised classification models can be trained to identify the tissue type based on the spectroscopic fingerprint. Infrared imaging spectrometers equipped with multi-channel detectors combine the spectral and spatial information. Tissue areas of 4 x 4 mm(2) can be analyzed within a few minutes in the macroscopic imaging mode. An approach is described to apply this methodology to human astrocytic gliomas, which are graded according to their malignancy from one to four. Multiple IR images of three tissue sections from one patient with a malignant glioma are acquired and assigned to the six classes normal brain tissue, astrocytoma grade II, astrocytoma grade III, glioblastoma multiforme grade IV, hemorrhage, and other tissue by a linear discriminant analysis model which was trained by data from a single-channel detector. Before the model is applied here, the spectra are shown to be virtually identical. The first specimen contained approximately 95% malignant glioma regions, that means astrocytoma grade III or glioblastoma. The smaller percentage of 12-34% malignant glioma in the second specimen is consistent with its location at the tumor periphery. The detection of less than 0.2% malignant glioma in the third specimen points to a location outside the tumor. The results were correlated with the cellularity of the tissue which was obtained from the histopathologic gold standard. Potential applications of IR spectroscopic imaging as a rapid tool to complement established diagnostic methods are discussed.     

Synthesis and electron transfer studies of ruthenium-terpyridine-based dyads attached to nanostructured TiO2

A series of bis(terpyridine)RuII complexes have been prepared, where one of the terpyridines is functionalized in the 4'-position by a phosphonic or carboxylic acid group for attachment to TiO2. The other is functionalized, also in the 4'-position, by a potential electron donor. In complexes 1a, 3a, and 4a,b, this donor is tyrosine or hydrogen-bonded tyrosine, while in 2a it is carotenoic amide. The synthesis and photophysical properties of the complexes are discussed. On irradiation with visible light, the formation of a long-lived charge-separated state was anticipated, via primary electron ejection into the TiO2, followed by secondary electron transfer from the donor to the photogenerated RuIII. However, such a charge-separated state could be observed with certainty only with complex 2a. To explain the result, quantum chemical calculations were performed on the different types of complexes.     

Near infrared Raman spectroscopic mapping of native brain tissue and intracranial tumors

This study assessed the diagnostic potential of Raman spectroscopic mapping by evaluating its ability to distinguish between normal brain tissue and the human intracranial tumors gliomas and meningeomas. Seven Raman maps of native specimens were collected ex vivo by a Raman spectrometer with 785 nm excitation coupled to a microscope with a motorized stage. Variations within each Raman map were analyzed by cluster analysis. The dependence of tissue composition on the tissue type in cluster averaged Raman spectra was shown by linear combinations of reference spectra. Normal brain tissue was found to contain higher levels of lipids, intracranial tumors have more hemoglobin and lower lipid to protein ratios, meningeomas contain more collagen with maximum collagen content in normal meninges. One sample was studied without freezing. Whereas tumor regions did not change significantly, spectral changes were observed in the hemoglobin component after snap freezing and thawing to room temperature. The results constitute a basis for subsequent Raman studies to develop classification models for diagnosis of brain tissue.     

Synthesis and characterization of dinuclear ruthenium complexes covalently linked to Ru(II) tris-bipyridine: an approach to mimics of the donor side of photosystem II

To mimic the electron-donor side of photosystem II (PSII), three trinuclear ruthenium complexes (2, 2a, 2b) were synthesized. In these complexes, a mixed-valent dinuclear Ru2(II,III) moiety with one phenoxy and two acetato bridges is covalently linked to a Ru(II) tris-bipyridine photosensitizer. The properties and photoinduced electron/energy transfer of these complexes were studied. The results show that the Ru2(II,III) moieties in the complexes readily undergo reversible one-electron reduction and one-electron oxidation to give the Ru2(II,III) and Ru2(III,III) states, respectively. This could allow for photooxidation of the sensitizer part with an external acceptor and subsequent electron transfer from the dinuclear ruthenium moiety to regenerate the sensitizer. However, all trinuclear ruthenium complexes have a very short excited-state lifetime, in the range of a few nanoseconds to less than 100 ps. Studies by femtosecond time-resolved techniques suggest that a mixture of intramolecular energy and electron transfer between the dinuclear ruthenium moiety and the excited [Ru(bpy)3]2+ photosensitizer is responsible for the short lifetimes. This problem is overcome by anchoring the complexes with ester- or carboxyl-substituted bipyridine ligands (2a, 2b) to nanocrystalline TiO2, and the desired electron transfer from the excited state of the [Ru(bpy)3]2+ moiety to the conduction band of TiO2 followed by intramolecular electron transfer from the dinuclear Ru2(II,III) moiety to photogenerated Ru(III) was observed. The resulting long-lived Ru2(III,III) state decays on the millisecond timescale.     

Efficient current-induced domain-wall displacement in SrRuO3

We demonstrate current-induced displacement of ferromagnetic domain walls in submicrometer fabricated patterns of SrRuO3 films. The displacement, monitored by measuring the extraordinary Hall effect, is induced at zero applied magnetic field and its direction is reversed when the current is reversed. We find that current density in the range of 10(9)-10(10) A/m2 is sufficient for domain-wall displacement when the depinning field varies between 50 to 500 Oe. These results indicate relatively high efficiency of the current in displacing domain walls which we believe is related to the narrow width (approximately 3 nm) of domain walls in this compound.     

Collector Probe Measurements of Impurity Fluxes Injected into the Plasma of the T-10 Tokamak

It is shown that the efflux of impurities injected into the core plasma can be detected by collector probes in the scrape-off plasma. The time evolution, orientation and radial dependences of these effluxes allow to conclude on the impurity confinement in the core plasma and the scrape-off plasma. Moreover, recycling effects can also be measured.     

Shanzhisin methyl ester gentiobioside,a new iridoid - isolation and synthesis

The title compound 1 has been isolated from $\text{Canthium subcordatum}$ and its structure deduced; 1 was synthesised from shanzhiside methyl ester.