TiCl4 and Grignard reagent-promoted ring-opening reactions of various epoxides: synthesis of γ-hydroxy-α,α-difluoromethylenephosphonates

A straightforward methodology for the synthesis of diethyl γ-hydroxy-α,α-difluoromethylenephosphonates is reported. In the presence of titanium tetrachloride, epoxide ring-opening reactions occurred upon treatment with lithium diethyl difluoromethylenephosphonate. When diethyl 3,4-epoxy-1,1-difluorobutylphosphonate was reacted with TiCl₄ and Grignard reagents, the corresponding halohydrins were obtained in very good yields.     

Microfluidic capture and release of bacteria in a conical nanopore array

We present a simple and inexpensive method for the capture and release of bacteria contained in an array of conical nanopores on a membrane inside a microfluidic device. As an example, we demonstrate that cyanobacteria can be captured, one bacterium per pore, in a defined orientation with over 500 bacteria per membrane with viabilities as high as 100%. The device can also specifically capture cyanobacteria from a mixed suspension of cyanobacteria and chlamydomonas with a selectivity as high as 90%.     

Open beauty production in high energy π−-tungsten interactions

We present a study of \(B\bar B\) meson pair production inπ ^? interactions at 140, 194 and 286 GeV incident pion energy. At 286 GeV, where we have the best statistics, we find a model-dependent \(B\bar B\) production cross-section \(\sigma _{BB} = 14_{ - 6}^{ + 7} nb/nucleon\) .     

Particle sorting using a porous membrane in a microfluidic device

Porous membranes have been fabricated based on the development of the perforated membrane mold [Y. Luo and R. N. Zare, Lab Chip, 2008, 8, 1688-1694] to create a single filter that contains multiple pore sizes ranging from 6.4 to 16.6 μm inside a monolithic three-dimensional poly(dimethylsiloxane) microfluidic structure. By overlapping two filters we are able to achieve smaller pore size openings (2.5 to 3.3 μm). This filter operates without any detectable irreversible clogging, which is achieved using a cross-flow placed in front of each filtration section. The utility of a particle-sorting device that contains this filter is demonstrated by separating polystyrene beads of different diameters with an efficiency greater than 99.9%. Additionally, we demonstrate the effectiveness of this particle-sorting device by separating whole blood samples into white blood cells and red blood cells with platelets.     

Curing kinetics study of melamine–urea–formaldehyde resin

The influence of the preconditioning at different temperatures on the cure kinetics of melamine?Curea?Cformaldehyde resins coated on stone wool was investigated under acidic conditions using differential scanning calorimetry and thermogravimetry. The higher pre-treatment temperature was applied, to which resin-coated stone wool was exposed, the lower was the mass loss during the experiment. Kinetic model parameters were determined in two different manners, with the parameters being independent of preconditioning temperature and dependent on the latter. The apparent orders of reaction were approximately two (all of them being within the range 0.96?C2.33), which would imply that cross-linking predominantly proceeds via the bimolecular reaction of either melamine or urea and formaldehyde. Nonetheless, the apparent orders of reaction decreased as a function of preconditioning temperature. The apparent activation energies varied less with preconditioning temperature, assuming values between 64.2 and 78.5?kJ?mol^?1. The applicability of nth-order reaction kinetic models was consequently validated for two other dynamic thermal regimes.     

Advanced vapor recognition materials for selective and fast responsive surface acoustic wave sensors: A review

The necessity of selectively detecting various organic vapors is primitive not only with respect to regular environmental and industrial hazard monitoring, but also in detecting explosives to combat terrorism and for defense applications. Today, the huge arsenal of micro-sensors has revolutionized the traditional methods of analysis by, e.g. replacing expensive laboratory equipment, and has made the remote screening of atmospheric threats possible. Surface acoustic wave (SAW) sensors – based on piezoelectric crystal resonators – are extremely sensitive to even very small perturbations in the external atmosphere, because the energy associated with the acoustic waves is confined to the crystal surface. Combined with suitably designed molecular recognition materials SAW devices could develop into highly selective and fast responsive miniaturized sensors, which are capable of continuously monitoring a specific organic gas, preferably in the sub-ppm regime. For this purpose, different types of recognition layers ranging from nanostructured metal oxides and carbons to pristine or molecularly imprinted polymers and self-assembled monolayers have been applied in the past decade. We present a critical review of the recent developments in nano- and micro-engineered synthetic recognition materials predominantly used for SAW-based organic vapor sensors. Besides highlighting their potential to realize real-time vapor sensing, their limitations and future perspectives are also discussed.     

The interaction of fluorescent nanodiamond probes with cellular media

Fluorescent nanodiamonds (FNDs) are promising tools to image cells, bioanalytes and physical quantities such as temperature, pressure, and electric or magnetic fields with nanometer resolution. To exploit their potential for intracellular applications, the FNDs have to be brought into contact with cell culture media. The interactions between the medium and the diamonds crucially influence sensitivity as well as the ability to enter cells. The authors demonstrate that certain proteins and salts spontaneously adhere to the FNDs and may cause aggregation. This is a first investigation on the fundamental questions on how (a) FNDs interact with the medium, and (b) which proteins and salts are being attracted. A differentiation between strongly binding and weakly binding proteins is made. Not all proteins participate in the formation of FND aggregates. Surprisingly, some main components in the medium seem to play no role in aggregation. Simple strategies to prevent aggregation are discussed. These include adding the proteins, which are naturally present in the cell culture to the diamonds first and then inserting them in the full medium.

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Graphical abstract Schematic of the interaction of nanodiamonds with cell culture medium. Certain proteins and salts adhere to the diamond surface and lead to aggregation or to formation of a protein corona.

     

Ion beam mixing of silicon-tin multilayers

Silicon and tin multilayers of total thickness 200 nm have been deposited at room temperature on beryllium and glass plate substrates under high vacuum (<5. 10^?7 mbar). The average atomic tin fraction of the whole layer varied from 0.12 to 0.60. The samples were irradiated at room temperature with Xe⁺ ions of 900 keV energy with fluences of 1.10¹⁵ to 2.10¹⁶ ions. cm^?2. Rutherford backscattering spectrometry (RBS) was used to check overall composition before irradiation. After irradiation, a substitutional Sn site was evidenced by means of¹¹⁹Sn conversion electron Mössbauer spectroscopy (CEMS), the relative population of which depends on composition and irradiation fluence. Transmission electron microscopy (TEM) was used to monitor the evolution of the samples with irradiation fluence. Electrical measurements show semiconductor behaviour of the mixed multilayers with electrical resistivity ranging from 10² to 10^?3 Ω.cm as a function of composition.     

Electrode and electrodeless impedance measurement for determination of orange juices parameters

Electrical impedance spectroscopy (EIS) is a non-destructive, rapid and real-time measurement method which does not require special high-tech measurement devices and can be applied to food quality assessment. This method is rapid, effective and affords low-cost investigation of the product. The conventional EIS method requires a set of metal electrodes in direct contact with the medium to be measured. The complicated electrochemical processes on the electrodes-electrolyte interface could substantially affect the value of the impedance measured. The present study sought to explore the possibilities of using the impedance method for quality control in orange juices, to introduce the electrodeless method of electrolyte impedance measurement and to compare this with the conventional impedance methods. The electrical properties of the orange juices were described with the help of an equivalent circuit. An equivalent circuit was designed with constant phase element approximation. The values of the equivalent circuit components were fitted using a non-standard algorithm inspired by the behaviour of actual ant colonies. Implementing the electrodeless method obviated the electrodes phenomena effects and the behaviour of the electrolyte is similar to inductance. The proposed electrodeless method is generally applicable to measuring the electrochemical properties of electrolytes.     

Structure and plasmonic properties of thin PMMA layers with ion‐synthesized Ag nanoparticles

Silver nanoparticles are synthesized in polymethylmethacrylate by 30 keV Ag⁺ ion implantation with high fluences. The implantation is accompanied by structural and compositional evolution of the polymer as well as sputtering. The latter causes towering of the shallow nucleated Ag nanoparticles above the surface. The synthesized nanoparticles can be split into two groups: (i) located at the surface and (ii) fully embedded in the shallow layer. These two groups provide corresponding spectral bands related to localized surface plasmon resonance. The bands demonstrate considerable intensity making the synthesized composites promising for plasmonic applications. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 664–672