Infra-red assisted sintering of inkjet printed silver tracks on paper substrates

In this study, conductive silver features using inkjet printing have been successfully prepared and their sintering studied. Regarding conductivity, metallic inks are the most efficient available conductive inks, even if important drawbacks regarding the use of such inks in inkjet still exist. Indeed, the sintering step is an important limiting factor for the productivity and the substrate choice. An infrared (IR) drying method was experimented to optimize the sintering treatment time. Trials with glass and paper substrates were performed and proved that IR drying is interesting to optimize sintering. Indeed a similar level of resistance was obtained for conventional heating (200 °C, 5 min) and for IR radiations within a shorter treatment time (3 min). Moreover, the substrate temperature during the IR sintering treatment was controlled. The substrate appears to be a relevant parameter to optimize sintering because its thermal behaviour directly impacts on the treatment duration. And for the first time a sheet resistance of 1.9 Ω sq⁻¹ was obtained on paper substrate after only 2 min of IR treatment without any observation of substrate degradation. The evaluation of an electrical treatment on the sintering of a nanoparticle film was also performed using a corona pre-treatment. This lead appears to be interesting because the study proves that an electrical treatment can initiate the sintering of silver nanoparticles. The current flow generated by the corona electrodes certainly generates a local heating by dissipation of the conductive pattern. Finally, the solutions presented in this article allow reducing the sintering time of silver conductive inkjet inks. However mainly, it proves that using paper as substrate for such inks is now possible.     

Encapsulated energy-transfer cassettes with extremely well resolved fluorescent outputs

This paper concerns the development of water-compatible fluorescent imaging probes with tunable photonic properties that can be excited at a single wavelength. Bichromophoric cassettes 1a-1c consisting of a BODIPY donor and a cyanine acceptor were prepared using a simple synthetic route, and their photophysical properties were investigated. Upon excitation of the BODIPY moiety at 488 nm the excitation energy is transferred through an acetylene bridge to the cyanine dye acceptor, which emits light at approximately 600, 700, and 800 nm, i.e., with remarkable dispersions. This effect is facilitated by efficient energy transfer that gives a "quasi-Stokes" shift between 86 and 290 nm, opening a huge spectral window for imaging. The emissive properties of the cassettes depend on the energy-transfer (ET) mechanism: the faster the transfer, the more efficient it is. Measurements of rates of ET indicate that a through-bond ET takes place in the cassettes 1a and 1b that is 2 orders of magnitude faster than the classical through-space, F?rster ET. In the case of cassette 1c, however, both mechanisms are possible, and the rate measurements do not allow us to discern between them. Thus, the cassettes 1a-1c are well suited for multiplexing experiments in biotechnological methods that involve a single laser excitation source. However, for widespread application of these probes, their solubility in aqueous media must be improved. Consequently, the probes were encapsulated in calcium phosphate/silicate nanoparticles (diameter ca. 22 nm) that are freely dispersible in water. This encapsulation process resulted in only minor changes in the photophysical properties of the cassettes. The system based on cassette 1a was chosen to probe how effectively these nanoparticles could be used to deliver the dyes into cells. Encapsulated cassette 1a permeated Clone 9 rat liver cells, where it localized in the mitochondria and fluoresced through the acceptor part, i.e., red. Overall, this paper reports readily accessible, cyanine-based through-bond ET cassettes that are lypophilic but can be encapsulated to form nanoparticles that disperse freely in water. These particles can be used to enter cells and to label organelles.     

Green synthesis and antioxidant activity of new PEGylated ferulic acids

PEGylation of ferulic acid is described through a green esterification process involving poly(ethylene glycol) (PEG) with three different average molecular weights (200, 400 and 1000 g/mol) as both reactive and solvent. Esterification with PEG400 and PEG1000 leads to original compounds soluble in all proportions in water. These new compounds display an antioxidant activity similar to that of ferulic acid.     

Elongated thrombin binding aptamer: a G-quadruplex cation-sensitive conformational switch

Aptamer-based biosensors offer promising perspectives for high performance, specific detection of proteins. The thrombin binding aptamer (TBA) is a G-quadruplex-forming DNA sequence, which is frequently elongated at one end to increase its analytical performances in a biosensor configuration. Herein, we investigate how the elongation of TBA at its 5'?end affects its structure and stability. Circular dichroism spectroscopy shows that TBA folds in an antiparallel G-quadruplex conformation with all studied cations (Ba(2+), Ca(2+), K(+), Mg(2+), Na(+), NH(4)(+), Sr(2+) and the [Ru(NH(3))(6)](2+/3+) redox marker) whereas other structures are adopted by the elongated aptamers in the presence of some of these cations. The stability of each structure is evaluated on the basis of UV spectroscopy melting curves. Thermal difference spectra confirm the quadruplex character of all conformations. The elongated sequences can adopt a parallel or an antiparallel structure, depending on the nature of the cation; this can potentially confer an ion-sensitive switch behavior. This switch property is demonstrated with the frequently employed redox complex [Ru(NH(3))(6)](3+), which induces the parallel conformation at very low concentrations (10 equiv per strand). The addition of large amounts of K(+) reverts the conformation to the antiparallel form, and opens interesting perspectives for electrochemical biosensing or redox-active responsive devices.     

Local Existence of a Solution of a Semilinear Wave Equation with Gradient in a Neighborhood of Initial Characteristic Hypersurfaces of a Lorentzian Manifold

We analyze an initial value problem for nonlinear wave equations with gradient in the second member, with data given on two transversely intersecting null hypersurfaces of a Lorentzian manifold. Existence and uniqueness of a solution is obtained in a (one-sided future) neighborhood of the initial data null hypersurfaces.     

Determination of the mechanism(s) for the inclusion of arsenate, vanadate, or molybdate anions into hydrotalcites with variable cationic ratio

Hydrotalcites with cationic ratios of 2:1, 3:1, and 4:1 were synthesised using the co-precipitation method. The mechanism of inclusion of arsenate, vanadate, and molybdate into these structures is investigated using the combination of X-ray diffraction, Raman spectroscopy, and thermal analysis. Results show that hydrotalcites with cationic ratios of 3:1 are thermally more stable then the 2:1 and 4:1 structures. The increase in thermal stability of the 3:1 hydrotalcite structures is understood to be due to the intercalation of arsenate, vanadate, or molybdate, by an increase in hydrogen bonds associated with the intercalated anion. The 3:1 vanadate hydrotalcite is the most thermally stable hydrotalcite investigated. It is observed that the predominant mechanism for inclusion of the three anionic species is adsorption for 2:1 and 4:1 hydrotalcites, and intercalation for the 3:1 hydrotalcite structures. The intercalation of arsenate, vanadate, and molybdate into the hydrotalcite structure increased the interlayer distance of the hydrotalcite by 0.14, 0.13, and 0.26 A, respectively.     

Application of adaptive multi-frequency grids to three-dimensional astrophysical radiative transfer

We present a method to solve the three-dimensional (3D) radiative transfer equation for astrophysical applications using adaptive photon transport grids. Contrary to earlier treatments, they are calculated for each frequency separately. Generated minimizing the first-order discretization error in the scattered radiation intensity, they provide global error control for solutions of radiative transfer problems on the grid. We discuss minimization of the grid point number in regions where the optical depth becomes large and show that the method allows for treating applications with optical depth of any value using the concept of penetration depth. The proposed grid generation algorithm is easy to implement, allows pre-calculation of the grids and storage in integer arrays, making a fast solution of the 3D radiative transfer equation possible. The grid generation algorithm is suitable for optimization in cases where simple radiation source distributions are given. Besides discussing application to simple density distribution commonly occurring in astrophysical objects, we illustrate the capabilities of the method by generating grids for an accretion disk around a young star.     

Transition to spatiotemporal chaos in a two-dimensional hydrodynamic system

We study the transition to spatiotemporal chaos in a two-dimensional hydrodynamic experiment where liquid columns take place in the gravity induced instability of a liquid film. The film is formed below a plane grid which is used as a porous media and is continuously supplied with a controlled flow rate. This system can be either ordered (on a hexagonal structure) or disordered depending on the flow rate. We observe, for the first time in an initially structured state, a subcritical transition to spatiotemporal disorder which arises through spatiotemporal intermittency. Statistics of numbers, creations, and fusions of columns are investigated. We exhibit a critical behavior close to the directed percolation one.     

Extraction and refinement of agricultural plant fibers for composites manufacturing

Because of their excellent tensile properties, low density, and natural abundance, cellulose-based plant fibers are a sustainable and biodegradable alternative for synthetic fibers in fiber-reinforced composite materials. However, the extraction of plant fibers can be costly and difficult to control because the fibers are enmeshed in a complex network of biopolymers (principally lignin, pectin, and hemicellulose), which serve both to strengthen the fibers and to bind them to their parent organism. It is necessary to extract or degrade these biopolymers to produce fine plant fibers without adversely altering the fibers themselves in the process. In particular, it is important that both the molecular weight and the degree of crystallinity of the cellulose in the fibers be kept as high as possible. This article reviews chemical treatments, which have been used to extract and refine fibers both from purpose-grown fiber crops, such as hemp and flax, and agricultural waste such as coconut husks and pineapple leaves. The treatments are discussed in terms of changes in the mechanical properties and surface chemistry of the fibers.     

Recognition of Complex Core‐Fucosylated N‐Glycans by a Mini Lectin

The mini fungal lectin PhoSL was recombinantly produced and characterized. Despite a length of only 40 amino acids, PhoSL exclusively recognizes N‐glycans with α1,6‐linked fucose. Core fucosylation influences the intrinsic properties and bioactivities of mammalian N‐glycoproteins and its level is linked to various cancers. Thus, PhoSL serves as a promising tool for glycoprofiling. Without structural precedence, the crystal structure was solved using the zinc anomalous signal, and revealed an interlaced trimer creating a novel protein fold termed β‐prism III. Three biantennary core‐fucosylated N‐glycan azides of 8 to 12 sugars were cocrystallized with PhoSL. The resulting highly resolved structures gave a detailed view on how the exclusive recognition of α1,6‐fucosylated N‐glycans by such a small protein occurs. This work also provided a protein consensus motif for the observed specificity as well as a glimpse into N‐glycan flexibility upon binding.