Toward single molecule detection of staphylococcal enterotoxin B: mobile sandwich immunoassay on gliding microtubules

An immunoassay based on gliding microtubules (MTs) is described for the detection of staphylococcal enterotoxin B. Detection is performed in a sandwich immunoassay format. Gliding microtubules carry the antigen-specific "capture" antibody, and bound analyte is detected using a fluorescent viral scaffold as the tracer. A detailed modification scheme for the MTs postpolymerization is described along with corresponding quantification by fluorescence spectroscopy. The resultant antibody-MTs maintain their morphology and gliding capabilities. We report a limit of detection down to 0.5 ng/mL during active transport in a 30 min assay time and down to 1 ng/mL on static surfaces. This study demonstrates the kinesin/MT-mediated capture, transport, and detection of the biowarfare agent SEB in a microfluidic format.     

Concentrations of Foliar Quercetin in Natural Populations of White Birch (Betula pubescens) Increase with Latitude

We investigated latitudinal and regional variations in the composition and concentrations of foliar flavonoids and condensed tannins in wild populations of white birch (Betula pubescens EHRH) in a large climatic transect in Finland. Concentrations of quercetin derivatives were correlated positively with latitude. By contrast, the concentrations of apigenin and naringenin derivatives were correlated negatively with latitude. These compound-specific latitudinal gradients compensated each other, resulting in no changes in the concentration of total flavonoids. Our results thus demonstrate a qualitative, but not quantitative, latitude-associated gradient in the foliar flavonoids in white birch. Due to higher antioxidant capacity of the quercetin derivatives in relation to other flavonoids, the qualitative change can reflect higher adaptation to light in the north than south. An investigation on a regional scale in the northern boreal zone showed that the temperature sum was correlated positively and soil P concentration was correlated negatively with the concentrations of foliar flavonoid, while the concentration of condensed tannins was correlated with slope. The variation in concentrations of flavonoids at large-scale geographical patterns is in line with the conjecture that foliar flavonoids are synthesized for protection against photooxidative stress.     

Organic Geochemical Evaluations of Bituminous Rock and Coals in Miocene Himmetoglu Basin (Bolu,Turkey)

Abstract

The studied area is a lake basin located in Bolu basin in Turkey. In the basin, from Upper Cretaceous to Upper Miocene 3,000-m thickness sediments were deposited. Upper Miocene Himmetoglu formation consisted of sandstone, claystone, and marl. To the middle level of the formation are located coal, bituminous limestone, and bituminous shales. In the basin, there are two coal beds whose thicknesses range from 1 to 13 m. The coals are easily breakable and black in color. In the coal beds exists some bituminous limestone and bituminous shales, and their thicknesses are between 5 and 45 cm. The amount of organic matter of the bituminous rocks from the Upper Miocene Himmetoglu formation are between 6.83 and 56.34 wt%, and the amount of organic matter of the bituminous limestone from the formation are between 13.58 and 57.16 wt%. These values indicate that these rocks have very good source potential. According to hydrogen index (HI), S ₂/S ₃, HI-T _max, and HI-OI (oxygen index) parameters, kerogen types of the bituminous rocks and coals belonging to Upper Miocene Himmetoglu formation are Type I, Type II, and Type III. In accordance with HI, S ₂/S ₃, HI-T _max, and HI-OI parameters, the bituminous rocks and coals from the Upper Miocene Himmetoglu formation are mostly immature.     

Investigation of Organic Carbon and Iron Group Elements in Bituminous Rocks

In this study, geochemical and biogeochemical features of the organic-rich bituminous shales of the Bolu-Mengen area were investigated. The deposition levels of carbon and iron group metals (Mn, Ni, V, Cr, Co, Ti, Sc) within the bituminous shales and their correlation were also examined. Samples studied contain high amount of organic carbon (Corg), and they have Type I and Type II kerogenes that can generally produce oil and gas. Corg distribution in the samples was found as 0.55–0.99% for 5 samples, 1.23–1.96% for 9 samples, 2.31–3.95% for 5 samples and 4.12–19.14% for 15 samples. 75–100% of the organic material is determined to be amorphous and algal. Corg and metal contents of the bituminous shales in the area are characteristic with cyclic changes. Samples with high Corg values show high correlation with Fe group elements. The variations in cogenetic Corg and metal contents in samples are also discussed.     

Odour and flavour perception in flavoured model systems: Influence of sodium chloride,umami compounds and serving temperature

The effects of salt (0% or 0.5% of NaCl) and umami compounds (0% or 0.3% of monosodium glutamate (MSG) + 0.15% of disodium salts of ribonucleotides) on odour and flavour attributes of beef broth model systems (BG) were studied at two serving temperatures (25 and 50 °C). Flavoured BG samples were prepared using 1-octen-3-ol (35 mg l^?1) and 2,6-dimethylpyrazine (100 mg l^?1) alone (BGO and BGD) or in combination (BGOD). A noticeable odour and flavour potentiator effect of NaCl on flavour intensities (overall, broth-like and saltiness in all samples; mushroom flavour in BGO and BGOD samples; nutty and cocoa flavour in BGD and BGOD samples), partly related to a “salting out” phenomenon, was found. Compared to 2,6-dimethylpyrazine, 1-octen-3-ol provided a less congruent flavour, which could explain the absence of a potentiator effect of umami compounds on mushroom flavour intensity. Cocoa and nutty flavour intensities increased with serving temperature in both BGD and BGOD model systems. However, mushroom odour and flavour increased in BGOD model systems but not in BGO samples, as a result of the likely enhancement effect displayed by the presence of 2,6-dimethylpyrazine. Salting-out phenomenon on particular aroma-active volatile compounds was established using sensory analysis. The potentiator flavour effect of MSG and NaCl was dependent on the characteristics of the model systems.     

Analysis of Neighbourhood Effects and Work Behaviour: Evidence from Paris

This paper highlights the effects of being located in a deprived neighbourhood on unemployment. Interest is focused on the consequences of neighbourhood effects. The paper uses the 1999 Population Census for Paris and the three surrounding sub-regional administrative districts in order to estimate different models that take into account the potential endogeneity bias of the residential location choice. The study first runs a bivariate probit model that includes the residential location as an endogenous variable. A probit model is also run on a sub-sample of households living in public housing with the idea that for them the location choice is exogenous. Whatever the method used, it is shown that living within the most deprived neighbourhoods, in terms of local composition, decreases the probability of employment.     

Natural frequencies and critical loads of beams and columns with damaged boundaries using Chebyshev polynomials

The effects of damaged boundaries on natural frequencies and critical loads of beams and columns of variable cross section with conservative and non-conservative loads are investigated. The shifted Chebyshev polynomials are used to solve the one-dimensional transverse vibration problem, in which the ordinary differential equation is reduced to an algebraic eigenvalue problem. The advantages of this method are that it is easily employed in a symbolic form and that the number of polynomials may be adjusted to attain convergence. In the present study, the damaged boundary is modeled by linear translational and torsional springs, and the effects of the damage severity on the natural frequencies are studied. It is shown that as the amount of damage increases the natural frequencies decrease at rates which vary with the mode number. The method is applied to the instability problems of both uniform and uniformly tapered beams with and without follower forces, and the results for the undamaged cases show agreement when compared with results available in the literature. Convergence studies are carried out to determine the number of Chebyshev polynomials that should be used in the proposed method.     

Colour properties,stability, and free radical scavenging activity of jambolan (Syzygium cumini) fruit anthocyanins in a beverage model system: Natural and copigmented anthocyanins

The colour and stability properties of jambolan anthocyanins, both natural and copigmented forms, were investigated in beverage model as well as their radical scavenging ability. Natural anthocyanins of jambolan revealed low colour intensity due to glycosylation structure of the anthocyanins as diglucoside. The intermolecular copigmentation of anthocyanins with sinapic acid, caffeic acid, ferulic acid, and rosemary polyphenolic extract could enhance the colour intensity, which was observed through spectrometric parameters, such as hyperchromic effect (ΔA_vis-max) and bathochromic shift (Δλ_vis-max). In addition of sinapic acid, caffeic acid, and rosemary polyphenolics also increased the stability of the anthocyanin colour during exposure to white fluorescent light and storage at refrigeration and room temperatures, whereas on high thermal treatments, this phenomenon was not observed. Furthermore, beverage model coloured with natural or copigmented anthocyanins revealed DPPH radical-scavenging activity. The AEAC values indicated that the beverage models with copigmented anthocyanins had higher scavenging activity than the beverage with natural anthocyanins.     

Correlation of nanostructural parameters and macromechanical behaviour of hyperbranched‐modified polypropylene using time‐resolved small‐angle X‐ray scattering measurements

Polypropylene (PP) is modified utilizing a poly(ester amide)‐based hyperbranched polymer (PS). A maleic‐modified PP is used to enhance the compatibility. Usual tensile experiments are carried out. The nanocrystalline structure is studied using small‐angle X‐ray scattering (SAXS) while a uniaxial mechanical load is simultaneously applied. SAXS patterns are analysed using procedures written in PV‐WAVE. The chord distribution function (CDF) is calculated and nanostructural parameters such as long period (l_p) and nanodeformation (?_Nano) are extracted. The correlations between macromechanical parameters and nanostructures are studied. Mechanical results show that PS has a plasticizing effect. Reactively blended samples demonstrate enhanced mechanical properties. SAXS patterns reveal a well‐known structure of PP as a peculiar architecture of the nanostructure. Crystalline branching occurs in a geometry that is known as a mother–daughter crystal lamellar structure, also called a crosshatching structure. It is concluded that adding PS distorts the stacking of crystalline domains. The structural information from SAXS patterns in reciprocal space is visualized in real space in the calculated CDFs. The CDFs indicate that in simple blends, l_p of the crystalline stacks increases compared to blank PP. Nevertheless, reactively blended samples show an increase of l_p compared to blank PP; however, they possess smaller l_p compared to simple blends. © 2012 Society of Chemical Industry     

Novel method of dispersion of multiwalled carbon nanotubes in a flexible epoxy matrix

We describe a simple and novel method for dispersing multiwalled carbon nanotubes (MWCNTs) in a flexible epoxy matrix. The MWCNTs were modified with half‐neutralized dicarboxylic acids having different numbers of carbon atoms. The modified MWCNTs were prereacted with epoxy in the presence of triphenylphosphine. The dispersion of the MWCNTs and the enhancement in the tensile properties were found to be better for composites prepared with a solvent. Among the half‐neutralized dicarboxylic acids used, half‐neutralized adipic acid (HNAA) exhibited the best performance. Scanning electron microscopy and transmission electron microscopy studies clearly indicated an improvement in the level of dispersion of the MWCNTs with the addition of the modifier. The good dispersion of the MWCNTs and the resulting improvement in their properties were attributed to the cation–π interactions (the cation of HNAA and the π‐electron clouds of the MWCNTs) between the HNAA and MWCNTs and the chemical bonding of ? COOH groups of HNAA and the epoxy resin. The cation–π interaction and chemical bonding was assessed with Fourier transform infrared spectroscopy and Raman spectroscopy. This approach did not destroy the π–electron clouds of the MWCNTs in contrast to a chemical functionalization strategy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2610–2618, 2013