Dynamic covalent hydrazine chemistry as a selective extraction and cleanup technique for the quantification of the Fusarium mycotoxin zearalenone in edible oils

A novel, cost-efficient method for the analytical extraction of the Fusarium mycotoxin zearalenone (ZON) from edible oils by dynamic covalent hydrazine chemistry (DCHC) was developed and validated for its application with high performance liquid chromatography-fluorescence detection (HPLC-FLD). ZON is extracted from the edible oil by hydrazone formation on a polymer resin functionalised with hydrazine groups and subsequently released by hydrolysis. Specifity and precision of this approach are superior to liquid partitioning or gel permeation chromatography (GPC). DCHC also extracts zearalanone (ZAN) but not α-/β-zearalenol or -zearalanol. The hydrodynamic properties of ZON, which were estimated using molecular simulation data, indicate that the compound is unaffected by nanofiltration through the resin pores and thus selectively extracted. The method's levels of detection and quantification are 10 and 30 μg/kg, using 0.2 g of sample. Linearity is given in the range of 10–20,000 μg/kg, the average recovery being 89%. Bias and relative standard deviations do not exceed 7%. In a sample survey of 44 commercial edible oils based on various agricultural commodities (maize, olives, nuts, seeds, etc.) ZON was detected in four maize oil samples, the average content in the positive samples being 99 μg/kg. The HPLC-FLD results were confirmed by HPLC–tandem mass spectrometry and compared to those obtained by a liquid partitioning based sample preparation procedure.     

Classroom Response Systems: Effects on the Critical Analysis Skills of Students in Introductory Science Courses

College instructors often teach scientific thinking by asking students to review and analyze a primary research article. The main purpose of this study was to explore how classroom response systems (CRS) could help impact the quality of written analysis papers submitted for this assignment by students taking 100‐level biology courses at a medium‐sized suburban, two‐year college in the northeastern United States. Students in all participating course sections received written instructions on five key elements of critical analysis (CA) to include in scientific study analysis papers. Classroom instruction on recognizing these key elements in primary research papers was provided either via CRS or via an instructor‐facilitated classroom discussion enhanced by the same PowerPoint presentation. A rubric, designed specifically for this assignment, was validated prior to its use in this study. Fifty students participated in the study, and those who received the CRS intervention achieved significantly higher CA scores for identifying implications of study findings, while the group that received only written instructions achieved significantly higher CA scores for discussing the credibility of the references used by the authors in planning the critiqued study. The implications of this study are discussed along with ideas for future research.     

Bounds on convex reliability functions with known first moments

In this paper, upper and lower bounds are derived for convex reliability functions (or survival functions) with known first n moments. The case where the mean and the variance are given (n = 2) is discussed in details and explicit expressions are provided. Extensions for n ? 3 moments are described. Comparisons with existing bounds are performed.     

α-Glucosidase inhibitory activity of marine sponges collected in Mauritius waters

This report describes the use of α-glucosidase to evaluate the anti-diabetic potential of extracts from marine sponges collected in the Mauritius waters. Initial screening at 1.0 mg/mL of 141 extracts obtained from 47 sponge species revealed 10 extracts with inhibitory activity greater than 85%. Seven of the 10 extracts were further tested at 0.1 and 0.01 mg/mL and only the methanol extract of two sponges namely Acanthostylotella sp. (ASSM) and Echinodictyum pykei (EPM) showed inhibition activity greater than 60% at 0.1 mg/mL with an IC₅₀ value of 0.16 ± 0.02 and 0.04 ± 0.01 mg/mL, respectively, while being inactive at 0.01 mg/mL.     

Surface‐Functionalized Nanoparticles by Olefin Metathesis: A Chemoselective Approach for In Vivo Characterization of Atherosclerosis Plaque

The use of click chemistry reactions for the functionalization of nanoparticles is particularly useful to modify the surface in a well‐defined manner and to enhance the targeting properties, thus facilitating clinical translation. Here it is demonstrated that olefin metathesis can be used for the chemoselective functionalization of iron oxide nanoparticles with three different examples. This approach enables, in one step, the synthesis and functionalization of different water‐stable magnetite‐based particles from oleic acid‐coated counterparts. The surface of the nanoparticles was completely characterized showing how the metathesis approach introduces a large number of hydrophilic molecules on their coating layer. As an example of the possible applications of these new nanocomposites, a focus was taken on atherosclerosis plaques. It is also demonstrated how the in vitro properties of one of the probes, particularly its Ca²⁺‐binding properties, mediate their final in vivo use; that is, the selective accumulation in atherosclerotic plaques. This opens promising new applications to detect possible microcalcifications associated with plaque vulnerability. The accumulation of the new imaging tracers is demonstrated by in vivo magnetic resonance imaging of carotids and aorta in the ApoE^?/? mouse model and the results were confirmed by histology.     

Enhanced ordering in gold nanoparticles self-assembly through excess free ligands

Self-assembly of nanometer-sized particles is an elegant and economical approach to achieve dense patterns over large areas beyond the resolution and throughput capabilities of electron-beam lithography. In this paper, we present results of self-assembly of oleylamine-capped gold nanoparticles with 8.0 ± 0.3 nm diameter into densely packed and well-ordered monolayers with center-to-center distance of ～11 nm. Self-assembly was done in a Langmuir-Blodgett trough and picked up onto Si substrates. The nanoparticles undesirably assembled within micrometer-sized "droplets" that were organic in nature. However, within these droplets, we observed that the addition of the excess ligand, oleylamine, drastically enhanced the self-assembly of the nanoparticles into monolayers with near-perfect ordering. This approach has the potential use in templated self-assembly of nanoparticles for rearranging poorly ordered assembly into a commensurate prepatterned substrate.     

Synthesis and characterisation of luminescent rhenium tricarbonyl complexes with axially coordinated 1,2,3-triazole ligands

A series of 1-alkyl-4-aryl-1,2,3-triazoles (1-methyl-4-phenyl-1,2,3-triazole (1a); 1-propyl-4-phenyl-1,2,3-triazole (1b); 1-benzyl-4-phenyl-1,2,3-triazole (1c); 1-propyl-4-p-tolyl-1,2,3-triazole (1d)) have been prepared through a one-pot procedure involving in situ generation of the alkyl azide from a halide precursor followed by copper catalysed alkyne/azide cycloaddition (CuAAC) with the appropriate aryl alkyne. Cationic Re(I) complexes [Re(bpy)(CO)(3)(1a-d)]PF(6) (2a-d) were then prepared by stirring [Re(bpy)(CO)(3)Cl] with AgPF(6) in dichloromethane in the presence of ligands 1a-d. X-ray crystal structures were obtained for 2a and 2b. In the solid state, 2a adopts a highly distorted geometry, which is not seen for 2b, in which the plane of the triazole ligand tilts by 13° with respect to the Re-N bond as a result of a π-stacking interaction between the Ph substituent and one of the rings of the bpy ligand. This π-stacking interaction also results in severe twisting of the bpy ligand. Infrared spectra of 2a-d exhibit ν(CO) bands at ～2035 and ～1926 cm(-1) suggesting that these ligands are marginally better donors than pyridine (ν(CO) = 2037, 1932 cm(-1)). The complexes are luminescent in aerated dichloromethane at room temperature with emission maxima at 542 to 552 nm comparable to that of the pyridine analogue (549 nm) and blue shifted relative to the parent chloride complex. Long luminescent lifetimes are observed for the triazole complexes (475 to 513 ns) in aerated dichloromethane solutions at room temperature.