Low-Temperature Plasma Sintering of Inkjet-Printed Metal Salt Decomposition Inks on Flexible Substrates

Due to their complex formulation, conductive nanoparticle inks for inkjet printing are limited in terms of the types of metals and substrates that can be utilized. A new and simplified class of inks called metal salt decomposition (MSD) inks has the potential to introduce a multitude of metals, which can be printed directly onto a wide range of substrates. Here, the use of atmospheric oxygen plasma to develop polycrystalline Au and Pt films at processing temperatures near room temperature (≈33 °C) with excellent conductivities up to 10⁵ S m⁻¹ is demonstrated. The conformal nature of the ink allows metal films to be printed onto a broad range of temperature-sensitive substrates including polymers, papers, and fabric. The Au ink is then used to build a simple light-emitting diode circuit showing its flexibility, durability, and long-term stability as deposited thin metal films. Additionally, such inks cost less than one-third the price of similar nanoparticle inks highlighting their overall affordability and good stability.     

Rheology of Cement Mortars with Crushed Fine Aggregates of Different Lithological Types

Crushed fine aggregates are widely used for full or partial replacement of natural sands in concretes. The crushed sands present different characteristics from the natural sand, especially if taking into account the content of microfine particle, the distribution of particle sizes, the shape features, besides the different lithological origin. From the rheological point of view, the crushed sands frequently provide mixtures with high yield stress, high viscosity, high cohesion and internal friction, which hinders its use in concrete. This study is focused on the evaluation of the rheological behavior of concrete mortar phase when using different lithological types of crushed sand in total replacement of natural sand. The lithological types surveyed were granite, calcitic limestone, dolomite limestone and mica schist. Each of these sand types was studied in two ways： in natura and with adjusted grading curve. The results show the best performance of calcitic limestone providing lower viscosities and lower yield stress in mortars.     

Stability of Aqueous Barium Titanate Suspensions for MLCC Inkjet Printing

BaTiO₃‐based materials are currently used for the fabrication of multilayer ceramic capacitors (MLCC) because of their high dielectric properties. The inkjet printing (IJP) process can be used to fabricate MLCC of complex configurations by integrating internal electrodes and dielectric layers in a single step using a multi printing‐head system. Stabilized aqueous suspensions of BaTiO₃‐based powders are required to obtain dielectric inks adapted to IJP. This study investigates the influence of BaTiO₃ powder hydrolysis in water on the surface chemistry and stability in relationship with the milling step used to adjust the powder grain size to IJP. Optimum parameters for a good stability of BaTiO₃ suspensions are identified. The selected dispersant is a polyacrylate (PAA) for which the content is adjusted to minimize the sedimentation rates as required by IJP. Moreover, the addition of ethylene glycol is shown to be necessary to avoid the formation of a gel structure which could result from the interaction of borates ions leached from the surface of BaTiO₃ with the PAA dispersant. A mechanism of gel formation is proposed.     

Reversibility of Thermal Transitions in Dilute Dioctadecyl-Dimethyl-Ammonium Bromide Vesicles

Dioctadecyl-dimethyl-ammonium bromide (DODAB) vesicles can be characterized by their differential scanning calorimetry (DSC) thermograms comprised of two endotherms at T _s ≈ 36 °C and T _m ≈ 45 °C in the heating, ascribed respectively to the subgel-to-gel and gel-to-liquid crystalline transitions, and two exotherms at T′_m ≈ 40 °C and T′_s ≈ 16 °C in the cooling, ascribed respectively to the liquid crystalline-to-gel and gel-to-subgel transitions. It has been reported but not proved that the T _m-transitions, the T′_m-transitions, the T _s-transitions, and the T′_s-transitions are reverse to each other, displaying hystheresis ΔT _m ≈ 5 °C and ΔT _s ≈ 20–25 °C, respectively. By investigating the effects of the initial scanning temperature (T _i) on the transition enthalpies (ΔH _m, ΔH _s, ΔH′_m and ΔH′_s), we have seen that these transitions are the reverse to each other and display different kinetics.     

Relaxation of rapidly quenched metallic glasses: Effect of the relaxation state on the slow low temperature dynamics

The relaxation spectrum of rapidly quenched Mg₆₅Cu₂₅Y₁₀ metallic glass ribbons is studied by mechanical spectroscopy at temperatures below and around the glass transition. The comparison between hyper-quenched and relaxed samples is used to examine the origin of the low temperature “excess wing” of internal friction commonly observed in mechanical spectroscopy of metallic glasses. The results show that the excess wing can be attributed to access of the system to the broad α-relaxation process while evidence of secondary relaxations is not found. This suggests that in this glassy system the activation energies of structural relaxation and low temperature deformation are directly related to the activation energy of the main relaxation process of the glassy state.     

Selenium Bioaccumulation in Shiitake Mushrooms: A Nutritional Alternative Source of this Element

Mushrooms have effective mechanisms to absorb and accumulate trace elements from substrates and, therefore could be used as a strategy to produce mineral-enriched food and nutritional supplements. This study aimed to enrich shiitake mushrooms with selenium (Se), an important dietary element in human health. Strains of Lentinula edodes (Berk.) were grown on artificial logs composed of eucalyptus sawdust, and were subjected to cold shock in water containing sodium selenite (Na(2) SeO(3) ) at concentrations of up to 1.28 mM. The content of Se in the mushrooms increased linearly with increasing amounts of Na(2) SeO(3) added to the cold water although above 0.96 mM, mushroom formation was inhibited. Concentrations greater than 17 mg Se 100/g of dried mushrooms were observed after treatment with 0.64 mM Na(2) SeO(3) . Shiitake mushroom had a demonstrate potential to offer an effective and economical way to produce Se-enriched products and, the strategy of adding selenite in cold water, used in this study, showed promising once it does not interfere with mycelial growth. Practical Application: Selenium is an essential trace element for both human and animals and is required for the 21st amino acid, selenocysteine, which is used for the synthesis of about a dozen selenoenzymes. In this study, it is demonstrated that shiitake mushroom is a good Se accumulator and only one step during fructification was necessary to obtained enriched mushroom. Se enriched shiitake mushroom can be considered to be an excellent source of this element and used to consumption in different ways.     

Synthesis and characterization of carboxymethylated red angico (Anadenanthera macrocarpa) exudate polysaccharide

Red angico is a heteropolysaccharide (arabinogalactan) obtained from Anadenanthera macrocarpa trees. Carboxymethylation of angico gum (AG) with monochloroacetic acid (MCA) in alkaline aqueous medium resulted in samples which were characterized by ¹³C nuclear magnetic resonance spectroscopy and gel permeation chromatography. The effects of reaction parameters, such as alkali concentration, MCA/AG ratio and temperature on the reaction yield and degree of substitution (DS) were investigated. The DS and MCA total efficiency values increase up to 2 h reaction time and then decrease. The DS varied from 0.11 to 1.10 depending on NaOH/MCA/AG ratio and temperature. The highest MCA total efficiency (0.57) was obtained for NaOH/MCA/AG molar ratio equal to 3:1:1, at 70°C. (DS = 0.63, yield = 91.0%). Nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC) analysis shows that polymer degradation was observed in all samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2985–2991, 2007     

Chitosan-coated pectin beads: Characterization and in vitro release of mangiferin

Microspheres of low degree of esterification (DE) pectin with calcium and the same sphere coated with chitosan (PCaC) were prepared. The spheres have diameters in the range 650–680 μm. The layer of chitosan is about of 5–15 μm thick. To obtain firm and stable PCaC beads, chitosan was reacetylated. Two different degrees of acetylation, giving PCaC50 and PCaC80 were adopted. The beads were characterized by FTIR, SEM and swelling measurements. Mangiferin was loaded in PCaC reacetylated in two different ways: by addition in pectin solution (M_p) and by addition in CaCl₂ solution (M_c). The yield in producing the beads, the efficiency in encapsulation and the content of mangiferin in beads were determined. A swelling kinetics study was done in simulated gastric fluid (SGF, pH 1.2) and in simulated intestine fluid (SIF, pH 7.4). The release of mangiferin from the beads was performed in SGF followed by the release in SIF. Based on the yield and efficiency in encapsulation the best bead was found to be PCaC50-M_p. The highest release (7.8 mg of mangiferin/g of bead) was achieved by the PCaC50-M_c. For all beads more bioactive was released in SGF than in SIF.     

High rate UWB CMOS transceiver chipset for WBAN and biomedical applications

This work presents a high rate UWB transceiver chipset implemented in a 130 nm CMOS technology for WBAN and biomedical applications in the 3–5 GHz band. The transmitter architecture is based on a double-filter excitation technique that can generate high magnitude pulses and address bipolar modulations such as BPSK. Measurements show that bipolar pulses with a peak-to-peak voltage of 1.9 Vpp for a power consumption of 139 µW@100 kbps can be generated. The receiver is a non-coherent architecture based on LNA followed by an envelope detector. A BER of 10^?3 is achieved for a 3–5 GHz input peak-to-peak amplitude of 3.4 mVpp which corresponds to a ?89.3 dBm sensitivity at 100 kbps. The energy consumption of the receiver and of the transmitter is respectively 0.144 nJ/bit and 196 pJ/bit at 100 Mbps. To improve the budget link of our non-coherent based transceiver a Randomly Alternate OOK signaling is proposed which leads to an estimated communication range of 2.36 m in a free space propagation channel.