Ultrasound treatment enhances cholesterol removal ability of lactobacilli

This study aimed to evaluate the effect of ultrasound treatment on the cholesterol removing ability of lactobacilli. Viability of lactobacilli cells was significantly increased (P < 0.05) immediately after treatment, but higher intensity of 100 W and longer duration of 3 min was detrimental on cellular viability (P < 0.05). This was attributed to the disruption of membrane lipid bilayer, cell lysis and membrane lipid peroxidation upon ultrasound treatment at higher intensity and duration. Nevertheless, the effect of ultrasound on membrane properties was reversible, as the viability of ultrasound-treated lactobacilli was increased (P < 0.05) after fermentation at 37 °C for 20 h. The removal of cholesterol by ultrasound-treated lactobacilli via assimilation and incorporation of cholesterol into the cellular membrane also increased significantly (P < 0.05) upon treatment, as observed from the increased ratio of membrane C:P. Results from fluorescence anisotropies showed that most of the incorporated cholesterol was saturated in the regions of phospholipids tails, upper phospholipids, and polar heads of the membrane bilayer.     

多介质流体界面的守恒型跟踪法

本文中,我们对茅德康在【D.K.Mao,Towards front-tracking based on conservation in two space dimensionsⅡ,tracking discontinuities in capturing fashion,J.Comput.Phys.,226,(2007),pp 1550-1588】一文中所建立的守恒型跟踪法进行了改进,成功将算法运用到多介质流体界面的计算中.最后,我们使用改进后的算法计算了两个数值算例,验证了算法的有效性.     

Simultaneous CO concentration and temperature measurements using tunable diode laser absorption spectroscopy near 2.3 μm

Simultaneous measurements of carbon monoxide (CO) mole fraction and temperature using tunable diode laser absorption spectroscopy (TDLAS) near 2.3 μm are reported. The measurement method uses ro-vibrational transitions [R(27): v″ = 1 → v′ = 3] and [R(6): v″ = 0 → v′ = 2] in the first overtone band of CO near 2.3 μm (~4,278 cm^?1). The measurements were performed in the post flame environment of fuel rich premixed ethylene–air flames with a N₂ co-flow, stabilized over a water cooled McKenna burner. Non-uniformity in the temperature and CO mole fraction, along the absorption line of sight, in the mixing layer of the co-flow, was considered during data analysis. The TDLAS based temperature measurements (±80 K) were in good agreement with those obtained using N₂ vibrational coherent anti-Stokes Raman scattering (±20 K), and the CO mole fraction measurements were in good agreement with the equilibrium values, for equivalence ratios lower than 1.8. A signal to noise ratio of 45 was achieved at an equivalence ratio of 1 for a CO concentration of 0.8 % at 1,854 K.     

A New,Simple and Versatile Strategy for the Synthesis of Short Segments of Zigzag‐Type Carbon Nanotubes

Short segments of zigzag single‐walled carbon nanotubes (SWCNTs) were obtained from a calixarene scaffold by using a completely new, simple and expedited strategy that allowed fine‐tuning of their diameters. This new approach also allows for functionalised short segments of zigzag SWCNTs to be obtained; a prerequisite towards their lengthening. These new SWCNT short segments/calixarene composites show interesting behaviour in solution. DFT analysis of these new compounds also suggests interesting photophysical behaviour. Along with the synthesis of various SWCNTs segments, this approach also constitutes a powerful tool for the construction of new, radially oriented π systems.     

Second-order advantage in determining Co (II) in real samples using kinetic-spectrophotometric data matrices and multivariate curve resolution-alternating least square approach

In the present study, multivariate curve resolution coupled to alternating least-squares (MCR-ALS) was used to analyze kinetic-spectroscopic second-order data. The purpose of the study was to achieve important second-order advantage under the conditions of extreme spectral overlapping among sample components. The obtained experimental data indicated that MCR-ALS, unlike other second-order multivariate calibration algorithms, can conveniently handle the investigated analytical problem provided that matrix augmentation is implemented in the spectral mode instead of the usual kinetic mode. In this work, row-wise augmentation was used to break rank deficiency under conditions of extreme spectral overlapping among sample components. The approach was applied to determine Cobalt (II) based on its oxidation reaction with Fe (III) and 1, 10-phenantroline in micellar media. The results indicated good analytical performance toward the analyte despite the intense spectral overlapping and the presence of unexpected constituents in the test samples. The maximum and minimum band boundaries of feasible solutions corresponding to the species profiles were estimated by multivariate curve resolution. The results of the study indicated that unique solution can be practically obtained using MCR-ALS under the selection of suitable constraints such as trilinearity.     

Chemically and Electrochemically Triggered Assembly of Viologen Radicals: Towards Multiaddressable Molecular Switches

We have established that bipyridinium radicals can be reversibly π‐dimerized under the combined effects of chemical (proton transfer) and electrochemical (electron transfer) stimuli. Our investigations also led to the discovery that a bis‐pyridinyl appended calixarene intermediate is involved in a fully reversible redox‐triggered σ‐dimerization process. The structure of the most stable intramolecular σ‐dimer was provided by computational chemistry and its complete conversion into a noncovalent π‐dimer could be triggered chemically by addition of protons, leading to the formation of protonated cation radicals. Theoretical data collected with the N‐methylated and N‐protonated π‐dimers also support the existence of multivariant orientations in π‐bonded dimers of viologen cation‐radicals.     

Ultra‐Tuning of the Rare‐Earth fcu‐MOF Aperture Size for Selective Molecular Exclusion of Branched Paraffins

Using isoreticular chemistry allows the design and construction of a new rare‐earth metal (RE) fcu ‐MOF with a suitable aperture size for practical steric adsorptive separations. The judicious choice of a relatively short organic building block, namely fumarate, to bridge the 12‐connected RE hexanuclear clusters has afforded the contraction of the well‐defined RE‐ fcu ‐MOF triangular window aperture, the sole access to the two interconnected octahedral and tetrahedral cages. The newly constructed RE (Y³⁺ and Tb³⁺) fcu ‐MOF analogues display unprecedented total exclusion of branched paraffins from normal paraffins. The resultant window aperture size of about 4.7 Å, regarded as a sorbate‐size cut‐off, enabled a complete sieving of branched paraffins from normal paraffins. The results are supported by collective single gas and mixed gas/vapor adsorption and calorimetric studies.     

Synthesis of highly dispersed,block copolymer‐grafted TiO2 nanoparticles within neat block copolymer films

The objective of the study is to formulate exclusive block copolymer (BCP) nanocomposites by dispersing bcp end‐grafted nanoparticles (bcp‐g‐nps) of PMMA‐b‐PS‐g‐TiO₂ within PS‐b‐PMMA matrix. PMMA‐b‐PS‐g‐TiO₂ is synthesized using a “grafting‐to” approach and characterized by XPS and TGA to establish that the copolymer chains were bonded to NPs. Good dispersion of bcp‐g‐nps in PMMA and PS‐PMMA bcp films is observed, in contrast to poor dispersion in PS films. In PS‐PMMA films, the compatible and identical bcp nature of the end‐grafted polymer, and large NP size caused it to span across entire PS‐PMMA domains. Poor and good dispersion in PS and PMMA matrices, respectively, can be rationalized by the fact that NPs interactions are driven by the PMMA at the outer corona of the bcp‐g‐nps. Developing bcp‐g‐nps as a strategic route to preparation of highly dispersed high permittivity NPs like titanium dioxide (TiO₂) in bcp matrix can have important ramifications for energy storage devices. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 468–478