Occurrence of 5α-cholesta-7,24-dien-3β-ol and 23-dehydrolophenol in the bean lipids of Vanilla madagascariensis

Eleven 4-desmethylsterols, four 4,4-dimethylsterols, and twelve 4-methylsterols were identified in Vanilla madagascariensis beans. The 4-desmethylsterol fraction was characterized by a high level of 5α-cholesta-7,24(25)-dien-3β-ol (35.3%). The 4-methylsterol fraction was characterized by a high level of 31-norcycloartenol (57.5%) and the presence of 23-dehydrolophenol (9.4%). Cycloartenol (72.9%), cyclosadol (12.7%), parkeol (9.7%), and 24-dehydrotirucallol (4.7%) were identified in the 4,4-dimethylsterol fraction.     

Myelinosome Organelles in the Retina of R6/1 Huntington Disease (HD) Mice: Ubiquitous Distribution and Possible Role in Disease Spreading

Visual deficit is one of the complications of Huntington disease (HD), a fatal neurological disorder caused by CAG trinucleotide expansions in the Huntingtin gene, leading to the production of mutant Huntingtin (mHTT) protein. Transgenic HD R6/1 mice expressing human HTT exon1 with 115 CAG repeats recapitulate major features of the human pathology and exhibit a degeneration of the retina. Our aim was to gain insight into the ultrastructure of the pathological HD R6/1 retina by electron microscopy (EM). We show that the HD R6/1 retina is enriched with unusual organelles myelinosomes, produced by retinal neurons and glia. Myelinosomes are present in all nuclear and plexiform layers, in the synaptic terminals of photoreceptors, in the processes of retinal neurons and glial cells, and in the subretinal space. In vitro study shows that myelinosomes secreted by human retinal glial Müller MIO-M1 cells transfected with EGFP-mHTT-exon1 carry EGFP-mHTT-exon1 protein, as revealed by immuno-EM and Western-blotting. Myelinosomes loaded with mHTT-exon1 are incorporated by naive neuronal/neuroblastoma SH-SY5Y cells. This results in the emergence of mHTT-exon1 in recipient cells. This process is blocked by membrane fusion inhibitor MDL 28170. Conclusion: Incorporation of myelinosomes carrying mHTT-exon1 in recipient cells may contribute to HD spreading in the retina. Exploring ocular fluids for myelinosome presence could bring an additional biomarker for HD diagnostics.     

Nanovolume analysis with secondary ion mass spectrometry using massive projectiles

A variant of secondary ion mass spectrometry is presented where the surface is bombarded with individual gold nanoparticles each resolved in time and space with a corresponding event-by-event detection of the secondary ions (SIs). The projectile used, Au400(4+), with impact energy of 136 keV, generates high SI yields. Typically, there is co-emission of multiple SIs from a single impact, i.e., emission of SIs from molecules co-located within a nanovolume with dimensions in the 10-nm range. The ability to detect co-located molecules was tested on samples consisting of alternating nanometric layers of oppositely charged polyions, poly(diallyldimethylammonium chloride), poly(styrenesulfonate) (PSS), and clay nanoplatelets. To achieve signal statistics, the chemical analysis was carried out with a sequence of stochastic impacts making this method suitable for characterization of similar nanoparticles or spots dispersed on a surface. Attomole detection sensitivity was achieved for PSS. The homogeneity of assembled layers could be assessed with approximately 10-nm resolution.     

Na2BaMg（PO4）2： synthesis, crystal structure and europium photoluminescence properties

Na2BaMg(PO4)2 was synthesized and characterized by X-ray diffraction, differential thermal analysis (DTA), 31P NMR spectroscopy and photoluminescence measurements. This compound crystallized in the P3m...     

Rheological studies of the cure of epoxy/polyester powder coatings containing titanium dioxide

The cure characteristics of a series of powder coatings containing titanium dioxide dispersed in an epoxy/polyester matrix are reported. The titanium dioxide pigments were produced via both the chloride and sulfate routes and coated with varying amounts of alumina and silica. Comparison data for formulations containing zinc oxide and silica are also included. The time to gelation for these powder coatings depends on a number of factors. Increasing the level of flow agent significantly reduces the time to gelation. The presence of traces of zinc inhibits cure in the case of the sulfate-based pigments. Varying levels of alumina and silica in the coating on the titanium dioxide coating also influence the time to gelation. Increasing the level of silica on the chloride-based coating increases the time to gelation, whereas in the case of the sulfate based coating the time to gelation is shortened. These differences are attributed to the effects of zinc in the coating and the effectiveness of the dicyandiamide catalysts.     

N-nitrosamines and residual nitrite in cured meats from the Dutch market

Summary A total of 140 samples of 16 kinds of cured meats were analyzed for contents of residual nitrite andN-nitrosamines. Nitrite was determined by reaction with sulfanilamide/naphthylethylenediamine and colorimetric measurement.N-nitrosamines were isolated from the samples by vacuum distillation and determined by gas-chromatography with chemiluminescence detection (GC-TEA). In six samples no nitrite was detectable (< 1 mg NaNO₂/kg), the remaining samples contained 1–140 mg NaNO₂/kg, median value 6.8 mg/kg. In 46 samples (33%) noN-nitrosamines were detected, i.e. less than 0.1–0.5 g/kg of the individual nitrosamines, depending upon their structure.N-nitrosodimethylamine (NDMA) was the nitrosamine present most frequently, in 75 samples, contents were 0.1–0.9 g/kg, mean 0.3 g/kg. OtherN-nitrosamines found were:N-nitrosopiperidine (NPIP), 10 times, 0.3-25 g/kg;N-nitrosodiethylamine (NDEA), three times, 0.2–0.9 g/kg;N-nitrosopyrrolidine (NPYR), three times, 1.3–4.2 g/kg;N-nitrosomorpholine, once, 0.7 g/kg andN-nitrosothiazolidine (NTHZ), 36 times, 0.5–91 g/kg, mean 5.7 g/kg. NTHZ was found most often and with the highest contents in smoked products. Frying of bacon and cured, smoked pork bellies led to substantially increased levels of NPYR in both products, and for the pork bellies also of NTHZ. In five samples of cured, smoked pork bellies after frying NTHZ-contents of 3.6–490 g/kg (mean 179) were found. No correlation between residual nitrite levels andN-nitrosamine contents could be established. Investigations during the nineteen seventies gave much higher levels for NDMA, NDEA, NPIP and NPYR in Dutch cured meats than now found; at that time NTHZ was not measured.

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N-Nitrosamine und Restnitrit in holländischen Fleischerzeugnissen

Zusammenfassung Insgesamt wurden 140 Proben von 16 verschiedenen Fleischerzeugnissen auf ihren Gehalt an Restnitrit und flüchtigenN-Nitrosamine geprüft Nitrit wurde nach Reaktion mit Sulfanilamid/Naphthylethylendiamin colorimetrisch bestimmt.N-Nitrosamine wurden mittels Vakuumdestillation aus den Proben isoliert und mit Gaschromatographie-Chemiluminescenzdetektion (GC-TEA) gemessen. In 6 Proben war kein Nitrit nachweisbar (< 1 mg NaN0₂/kg), die Nitritgehalte der übrigen Proben lagen zwischen 1 und 140 mg NaNO₂/kg, Medianwert 6,8 mg/kg. In 46 Proben (33%) waren keineN-Nitrosamine nachweisbar d.h. weniger als 0,1–0,5 g/kg.N-Nitrosodimethylamin (NDMA) kam am häufigsten vor, in 75 Proben mit Gehalten von 0,1–0,9 g/kg, Mittelwert 0,3 g/kg. Von den sonstigen Nitrosaminen waren nachweisbar:N-Nitrosopiperidin (NPIP), 0,3–25 g/kg (zehnmal);N-Nitrosodiethylamin (NDEA), 0,2–91 g/kg (dreimal),N-Nitrosopyrrolidin (NPYR), 1,3–4,2 g/kg (dreimal),N-Nitrosomorpholin (NMOR), 0,7 g/kg (einmal) undN-Nitrosothiazolidin (NTHZ), 0,5–91 g/kg (36mal), Mittelwert 5,7 g/kg. NTHZ wurde am häufigsten und mit den höchsten Mengen in geräucherten Produkten gefunden. Braten von Bacon und Frühstückspeck erhöhte die Gehalte an NPYR erheblich in beiden Produkten und bei Frühstückspeck auch den Gehalt an NTHZ. In 5 Proben Frühstückspeck wurden nach dem Braten NTHZ-Gehalte von 3,6–490 g/kg (Mittelwert 179) gemessen. Es konnte keine Beziehung zwischen den Gehalten an Restnitrit undN-Nitrosaminen festgestellt werden. Untersuchungen in den siebziger Jahren ergaben viel höhere Gehalte an NDMA, NDEA, NPIP und NPYR in holländischen Fleischwaren als die jetzt gefundenen; auf NTHZ wurde damals nicht analysiert.

     

Mapping local microstructure and mechanical performance around carbon nanotube grafted silica fibres: methodologies for hierarchical composites

The introduction of carbon nanotubes (CNTs) modifies bulk polymer properties, depending on intrinsic quality, dispersion, alignment, interfacial chemistry and mechanical properties of the nanofiller. These effects can be exploited to enhance the matrices of conventional microscale fibre-reinforced polymer composites, by using primary reinforcing fibres grafted with CNTs. This paper presents a methodology that combines atomic force microscopy, polarised Raman spectroscopy, and nanoindentation techniques, to study the distribution, alignment and orientation of CNTs in the vicinity of epoxy-embedded micrometre-scale silica fibres, as well as, the resulting local mechanical properties of the matrix. Raman maps of key features in the CNT spectra clearly show the CNT distribution and orientation, including a 'parted' morphology associated with long grafted CNTs. The hardness and indentation modulus of the epoxy matrix were improved locally by 28% and 24%, respectively, due to the reinforcing effects of CNTs. Moreover, a slower stress relaxation was observed in the epoxy region containing CNTs, which may be due to restricted molecular mobility of the matrix. The proposed methodology is likely to be relevant to further studies of nanocomposites and hierarchical composites.     

Parametric analysis of runway stone lofting mechanisms

The influence of various factors affecting the severity of runway debris lofting mechanisms was investigated by performing numerical simulations and drop-weight impact experiments to assess the likelihood of a stone impact. Geometrical characterisation of stones collected from airfields led to a generic model of a tyre rolling over stones of various shape with different overlaps, orientations, and densities. In numerical simulations of a 0.4 m diameter aircraft tyre rolling at 70 m/s, a 10 mm diameter spherical stone was lofted at a maximum vertical speed of 35 m/s. For equivalent mass prolate spheroid stones, the loft speeds were 11–34% lower depending on the stone orientation. Objects with flat surfaces exhibited different lofting mechanisms and lower angular velocities. The conditions most conducive to stone lofting were very stiff, small diameter, sharp cornered tyres rolling on ground with a high friction coefficient over spherical stones such that just under half the stone diameter was covered by the tyre. The stone loft speed was approximately proportional to the square root of the tyre tread stiffness. Finally, tyre tread grooves could throw stones upwards at the tyre-ground separation speed, which was 17 m/s for the conditions mentioned earlier.