Numerical Study on an RBF-FD Tangent Plane Based Method for Convection–Diffusion Equations on Anisotropic Evolving Surfaces

In this paper, we present a fully Lagrangian method based on the radial basis function (RBF) finite difference (FD) method for solving convection–diffusion partial differential equations (PDEs) on evolving surfaces. Surface differential operators are discretized by the tangent plane approach using Gaussian RBFs augmented with two-dimensional (2D) polynomials. The main advantage of our method is the simplicity of calculating differentiation weights. Additionally, we couple the method with anisotropic RBFs (ARBFs) to obtain more accurate numerical solutions for the anisotropic growth of surfaces. In the ARBF interpolation, the Euclidean distance is replaced with a suitable metric that matches the anisotropic surface geometry. Therefore, it will lead to a good result on the aspects of stability and accuracy of the RBF-FD method for this type of problem. The performance of this method is shown for various convection–diffusion equations on evolving surfaces, which include the anisotropic growth of surfaces and growth coupled with the solutions of PDEs.     

Identification of extracellular nanoparticle subsets by nuclear magnetic resonance

Exosomes are a subset of secreted lipid envelope-encapsulated extracellular vesicles (EVs) of 50–150 nm diameter that can transfer cargo from donor to acceptor cells. In the current purification protocols of exosomes, many smaller and larger nanoparticles such as lipoproteins, exomers and microvesicles are typically co-isolated as well. Particle size distribution is one important characteristics of EV samples, as it reflects the cellular origin of EVs and the purity of the isolation. However, most of the physicochemical analytical methods today cannot illustrate the smallest exosomes and other small particles like the exomers. Here, we demonstrate that diffusion ordered spectroscopy (DOSY) nuclear magnetic resonance (NMR) method enables the determination of a very broad distribution of extracellular nanoparticles, ranging from 1 to 500 nm. The range covers sizes of all particles included in EV samples after isolation. The method is non-invasive, as it does not require any labelling or other chemical modification. We investigated EVs secreted from milk as well as embryonic kidney and renal carcinoma cells. Western blot analysis and immuno-electron microscopy confirmed expression of exosomal markers such as ALIX, TSG101, CD81, CD9, and CD63 in the EV samples. In addition to the larger particles observed by nanoparticle tracking analysis (NTA) in the range of 70–500 nm, the DOSY distributions include a significant number of smaller particles in the range of 10–70 nm, which are visible also in transmission electron microscopy images but invisible in NTA. Furthermore, we demonstrate that hyperpolarized chemical exchange saturation transfer (Hyper-CEST) with ¹²⁹Xe NMR indicates also the existence of smaller and larger nanoparticles in the EV samples, providing also additional support for DOSY results. The method implies also that the Xe exchange is significantly faster in the EV pool than in the lipoprotein/exomer pool.

Diffusion and xenon NMR based methods to determine a very broad range of sizes and sub-sets of extracellular vesicles.     

New heteroleptic palladium(II) dithiocarbamates: synthesis,characterization, packing and anticancer activity against five different cancer cell lines

Two new heteroleptic palladium(II) complexes have been synthesized by reacting equimolar quantities of palladium(II) chloride, sodium 4‐(2‐methoxyphenyl)piperazine‐1‐carbodithioate and diphenyl‐p‐tolylphosphine ( 1 ) or tri‐p‐tolylphosphine ( 2 ). Complexes 1 and 2 have been characterized using elemental analysis, Fourier transform infrared spectroscopy, multinuclear NMR (¹H, ¹³C and ³¹P) spectroscopy and single‐crystal X‐ray analysis. The latter technique confirms a pseudo square‐planar geometry in which two adjacent positions are occupied by bidentate dithiocarbamate while chloro and substituted triphenylphosphine are present at the remaining two positions. The anticancer activity of both complexes against five different cancer cell lines (LU – human lung carcinoma, established at UIC, Department of Surgical Oncology; MCF7 – human breast adenocarcinoma, ATCC number HTB‐22?; MDA‐MB‐231 – human breast adenocarcinoma, ATCC number HTB‐26?; Hepa‐1c1c7 – mouse liver hepatoma, ATCC number CRL‐2026?; PC‐3 – human prostate adenocarcinoma, ATCC number CRL‐1435?) was determined by MTT assay, revealing 2 has higher activity than 1 . A drug–calf thymus DNA binding study with UV–visible spectroscopy reveals a higher DNA binding affinity of 2 (3.511 × 10⁴ M^?1) than 1 (4.213 × 10³ M^?1). Density functional theory studies confirm the relatively more stable nature of 2 than 1 . Copyright © 2016 John Wiley & Sons, Ltd.     

Enantioselective and Regiodivergent Functionalization of N‐Allylcarbamates by Mechanistically Divergent Multicatalysis

A pair of mechanistically divergent multicatalytic reaction sequences has been developed consisting of nickel‐catalyzed isomerization of N‐allylcarbamates and subsequent phosphoric‐acid‐catalyzed enantioselective functionalization of the resulting intermediates. By appropriate selection of reaction partners, in situ generated imines and ene‐carbamates are mechanistically partitioned to yield opposing functionalized products. Formal α‐functionalization to give protected α‐arylamines is achieved upon enantioselective Friedel–Crafts reaction with arene nucleophiles, whereas formal β‐functionalization is achieved upon reaction with diarylimine electrophiles in an enantioselective Povarov‐[4+2] cycloaddition.     

Simultaneous determination of perfluoroalkyl phosphonates, carboxylates, and sulfonates in drinking water

A trace analytical method based on high performance liquid chromatography coupled to quadrupole time-of-flight high resolution mass spectrometry was developed for simultaneous determination of perfluoroalkyl phosphonates (PFPAs, carbon chain lengths C6,8,10), perfluoroalkyl carboxylates (PFCAs, C5-12), and perfluoroalkyl sulfonates (PFSAs, C4,6,8,10) in drinking water (tap water). Analytes were enriched on a mixed mode co-polymeric sorbent (C8+quaternary amine) using solid phase extraction. Chromatographic separation was achieved on a Zorbax Extend C18 reversed phase column using a mobile phase gradient consisting of water, methanol, and acetonitrile containing 2mM ammonium acetate and 5 mM 1-methyl piperidine. The mass spectrometer was operated in electrospray negative ion mode. Use of 1-methyl piperidine in the mobile phase resulted in a significant increase in instrument sensitivity for PFPAs through improved chromatographic resolution, background suppression, and increased ionization efficiency. Method detection limits for extraction of 500 mL tap water were in the ranges of 0.095-0.17 ng/L, 0.027-0.17 ng/L, and 0.014-0.052 ng/L for PFPAs, PFCAs, and PFSAs, respectively. Whole method recoveries at a spiking level of 0.5 ng/L to 500 mL HPLC grade water were 40-56%, 56-97%, and 55-77% for PFPAs, PFCAs, and PFSAs, respectively. A matrix effect (signal enhancement) was observed in the detection of PFPAs in tap water extracts, leading to calculated recoveries of 249-297% at a 0.5 ng/L spiking level. This effect resulted in an additional improvement of method sensitivity for PFPAs. To compensate for the matrix effect, PFPAs in tap water were quantified using matrix-matched and extracted calibration standards. The method was successfully applied to the analysis of drinking water collected from six European countries. PFPAs were not detected except for perfluorooctyl phosphonate (PFOPA) at close to the detection limit of 0.095 ng/L in two water samples from Amsterdam, the Netherlands. Highest levels were found for perfluorobutane sulfonate (PFBS, 18.8 ng/L) and perfluorooctanoate (PFOA, 8.6 ng/L) in samples from Amsterdam as well as for perfluorooctane sulfonate (PFOS, 8.8 ng/L) in tap water from Stockholm, Sweden.     

Apparent Solubility of Ibuprofen in Dimethyl Dodecyl Ammonium-Propane Sulfonate, DDAPS, Micelles, DDAPS/Butanol Mixtures and in Oil-in-Water Microemulsions Stabilized by DDAPS

Solubility of drugs in aqueous media is a real issue for scientists and a lot of work is going on to resolve the issue. The same is the case for ibuprofen, which is a derivative of propionic acid, belongs to the NSAIDs family and has low solubility in pure water. Therefore, its solubility has been investigated in dimethyl dodecyl ammonium-propane sulfonate, DDAPS, micellar solution, DDAPS/butanol mixtures and in various (hexane, decane and tetradecane) oil-in-water microemulsions to find out a suitable vehicle. The aggregation number, size and flow ability of micelles and microemulsions were estimated using refractive index, viscosity and light scattering measurements. It has been observed that these microemulsions have a higher ability to solubilize ibuprofen than DDAPS/butanol mixtures or DDAPS micelles.     

Miscellaneous applications of ferrocene‐based peptides/amides

This article provides a critical review of the different applications of ferrocene‐based peptides/amides in biological as well as in non‐biological systems. Ferrocene‐based peptides/amides find many applications in different fields such as materials science, medicine, organic synthesis, bio‐organometallic and biological chemistry, asymmetric catalysis, nonlinear optics, in polymer science as redox active polymers and dendrimers, in molecular recognition as biosensors and in electrochemistry). Extensive research is being done on ferrocene‐based peptides/amides but we will highlight the various applications of ferrocene‐based peptides/amides for the period 2006–2010. The main factors that govern the potential biological and non‐biological applications are an electroactive core, a conjugated linker that can act as a chromophore and lower the oxidation potential of the ferrocene part, an amino acid or peptide derivative that can interact with other molecules via hydrogen bonding or any secondary bonding, and symmetric and asymmetric substitution on the ferrocene moiety. Copyright © 2011 John Wiley & Sons, Ltd.     

Experimental comparison of performance and emission characteristics of 4-stroke CI engine operated with Roselle and Jatropha biodiesel blends

The environmental degradation, combined with the continuous depletion of the world's fossil fuel reserves, has forced the search for alternative fuels. This study was performed to investigate the performance of novel biodiesels in the CI engine. The experiments were performed at three different compressions ratios (16:1, 17:1, 18:1) and four loading conditions (25%, 50%, 75%, 100%). Different types of fuels such as jatropha biodiesel (JB), roselle biodiesel (RB), and ternary biodiesel (TB) were prepared and analyzed. The thermal performance of different fuels was analyzed in terms of brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), and exhaust gas temperature (EGT). The emission characteristics such as CO₂ emission, NO_x emission, and smoke emission were analyzed for all types of fuels. The results of these fuels in the engine were compared with mineral diesel (MD). The BTE was increased with increasing compression ratios and loads for all types of fuels. The BSFC was increased with increasing compression ratios but decreased with increasing loads. The increase in emission of NO_x was observed at higher compression ratios and loads. However, the CO₂ emission was decreased at higher loads and lower compression ratio. The performance curves achieved with a 20% jatropha biodiesel blend showed results that were approximate to those obtained with pure MD. The comparative analysis between different fuels showed that JB exhibit higher thermal performance as compared to other biodiesels. Therefore, JB can be a better alternative to conventional fuel.