<Emphasis Type=Italic>trans</Emphasis>-Fatty Acid Isomers in Adipose Tissue Have Divergent Associations with Adiposity in Humans

The aim of this study was to evaluate the association between adipose tissue trans-fatty acid isomers and adiposity. This cross-sectional study included 1,785 subjects from Costa Rica. Fatty acid concentrations (as a percentage of the total fatty acids) in subcutaneous adipose tissue were assessed by gas–liquid chromatography. Dietary intakes were assessed with a food frequency questionnaire. Multivariate linear regression models were used to relate adipose tissue trans-fatty acid content to BMI, waist circumference, and skinfold thickness while adjusting for age, sex, and area of residence. To account for variations in lifestyle, we adjusted for smoking, physical activity, income, self-reported history of diabetes and hypertension, and for adipose tissue alpha-linolenic acid and energy intake in a third model. After adjustments, positive associations were found between 18:2t-fatty acids (primarily from partially hydrogenated oils) and BMI, waist circumference, and skinfold thickness (P for each association <0.01). Rumenic acid was positively associated with skinfold thickness (P < 0.0001), but not with BMI or waist circumference (P > 0.05). Inverse associations were found between 16:1n-7t-fatty acids and skinfold thickness and between 18:1t-fatty acids and BMI and waist circumference (P < 0.0001). This study suggests that individual trans-fatty acid isomers may have divergent effects on adiposity. 18:2t-fatty acids show consistent positive associations with measures of adiposity. These isomer-specific associations are an interesting new finding. Other prospective and intervention studies are necessary to examine these relationships further.     

DLTS study of the influence of annealing on deep level defects induced in xenon ions implanted n-type 4H-SiC

In this study, nitrogen-doped 4H-SiC samples were bombarded with 167 MeV xenon ions to a fluence of 1?×?10⁸ cm^?2 at 300 K prior to the fabrication of Schottky barrier diodes. The implanted samples were annealed at approximately 900 °C for 1 h before the resistive evaporation of nickel Schottky barrier diodes. In comparing the current–voltage results of the implanted devices with as-deposited ones, generation-recombination took place in the implanted Schottky barrier diodes. Four defects (100, 120, 170, and 650 meV) were present in as-deposited Schottky barrier diodes when characterized by deep level transient spectroscopy (DLTS). In addition to the defects observed in the as-deposited samples, two additional defects with activation energies of 400 and 700 meV below the conduction band minimum were induced by Xe ions implantation. The two deep level defects present have signatures similar to defects present after irradiated by MeV electron. The two defects present after irradiation disappeared after annealing at 400 °C which indicate instability of the defects after annealing implanted samples.

     

Identification of ritual blood in African artifacts using TOF-SIMS and synchrotron radiation microspectroscopies

A new protocol is implemented to demonstrate the presence of blood in the patina of African art objects from Mali. Divided into three steps, the protocol first consists in demonstrating the presence of proteins and localizing them in the sample's cross sections using time-of-flight secondary ion mass spectrometry (TOF-SIMS) and synchrotron-based infrared microspectrometry (microFT-IR). In a second time, TOF-SIMS is used to investigate heme, which is a blood marker. If heme is missing, which could mean that it is too degraded to be detected, X-ray microfluorescence (microXRF) and X-ray absorption near-edge microspectroscopy (microXANES) are used to prove the presence of iron in the protein area and to get a fingerprint of its chemical environment. This permits us thus to demonstrate that iron is indeed linked with proteins and not with mineral phases of the sample. Coupled with the ritual context of the objects, this constitutes a proof of the use of blood. Thanks to this protocol, which has the major advantage of avoiding false positive results, the presence of blood has been demonstrated in seven out of the eight studied samples.     

Infrared Spectrum of the v2+ v6 Band of C13C12H6

The infrared spectrum of the v₂+v₆ band of C¹³C¹²H₆ has been analyzed and a value of B₀= 0.64865 ±0.00005 cm⁻¹ determined. When this value is combined with that found in recent work on isotopically normal ethane, a “r_s” value of 1.527±0.004 A for the carboncarbon bond distance is obtained. (Uncertainties are probable errors.)     

Recent advances in atomic-scale spin-polarized scanning tunneling microscopy

The Mn3N2 (010) surface has been studied using spin-polarized scanning tunneling microscopy at the atomic scale. The principle objective of this work is to elucidate the properties and potential of this technique to measure atomic-scale magnetic structures. The experimental approach involves the use of a combined molecular beam epitaxy/scanning tunneling microscopy system that allows the study of atomically clean magnetic surfaces. Several key findings have been obtained. First, both magnetic and non-magnetic atomic-scale information has been obtained in a single spin-polarized image. Magnetic modulation of the height profile having an antiferromagnetic super-period of c = 12.14 A (6 atomic rows) together with a non-magnetic superstructure having a period of c/2 = 6.07 A (3 atomic rows) was observed. Methods of separation of magnetic and non-magnetic profiles are presented. Second, bias voltage-dependent spin-polarized images show a reversal of the magnetic modulation at a particular voltage. This reversal is clearly due to a change in the sign of the magnetic term in the tunnel current. Since this term depends on both the tip's as well as the sample's magnetic local density of states, the reversal can be caused by either the sample or the tip. Third, the shape of the line profile was found to vary with the bias voltage, which is related to the energy-dependent spin contribution from the 2 chemically inequivalent Mn sites on the surface. Overall, the results shown here expand the application of the method of spin-polarized scanning tunneling microscopy to measure atomic-scale magnetic structures.     

PixFRET, an ImageJ plug-in for FRET calculation that can accommodate variations in spectral bleed-throughs

Fluorescence resonance energy transfer (FRET) allows the user to investigate interactions between fluorescent partners. One crucial issue when calculating sensitized emission FRET is the correction for spectral bleed-throughs (SBTs), which requires to calculate the ratios between the intensities in the FRET and in the donor or acceptor settings, when only the donor or acceptor are present. Theoretically, SBT ratios should be constant. However, experimentally, these ratios can vary as a function of fluorophore intensity, and assuming constant values may hinder precise FRET calculation. One possible cause for such a variation is the use of a microscope set-up with different photomultipliers for the donor and FRET channels, a set-up allowing higher speed acquisitions on very dynamic fluorescent molecules in living cells. Herein, we show that the bias introduced by the differential response of the two PMTs can be circumvented by a simple modeling of the SBT ratios as a function of fluorophore intensity. Another important issue when performing FRET is the localization of FRET within the cell or a population of cells. We hence developed a freely available ImageJ plug-in, called PixFRET, that allows a simple and rapid determination of SBT parameters and the display of normalized FRET images. The usefulness of this modeling and of the plug-in are exemplified by the study of FRET in a system where two interacting nuclear receptors labeled with ECFP and EYFP are coexpressed in living cells.     

Influence of concrete strength and length/diameter on the axial capacity of CFT columns

This paper presents an experimental analysis of the confinement effects in steel–concrete composite columns regarding two parameters: concrete compressive strength and column slenderness. Sixteen concrete-filled steel tubular columns with circular cross section were tested under axial loading. The tested columns were filled by concrete with compressive strengths of 30, 60, 80, and 100 MPa, and had length/diameter ratios of 3, 5, 7, and 10. The experimental values of the columns’ ultimate load were compared to the predictions of 4 code provisions: the Brazilian Code NBR 8800:2008, Eurocode 4 (EN 1994-1-1:2004), AINSI/AISC 360:2005, and CAN/CSA S16-01:2001. According to the results, the load capacity of the composite columns increased with increasing concrete strength and decreased with increasing length/diameter ratio. In general, the code provisions were highly accurate in the prediction of column capacity. Among them, the Brazilian Code was the most conservative, while Eurocode 4 presented the values closest to the experimental results.