Silk‐Pectin Hydrogel with Superior Mechanical Properties,Biodegradability, and Biocompatibility

A new method is developed to prepare silk hydrogels and silk‐pectin hydrogels via dialysis against methanol to obtain hydrogels with high concentrations of silk fibroin. The relationship between the mechanical and biological properties and the structure of the silk‐pectin hydrogels is subsequently evaluated. The present results suggest that pectin associates with silk molecules when the silk concentration exceeds 15 wt%, suggesting that a silk concentration of over 15 wt% is critical to construct interacting silk‐pectin networks. The silk‐pectin hydrogel reported here is composed of a heterogeneous network, which is different from fiber‐reinforced, interpenetrated networks and double‐network hydrogels, as well as high‐stiffness hydrogels (elastic modulus of 4.7 ± 0.9 MPa, elastic stress limit of 3.9 ± 0.1 MPa, and elastic strain limit of 48.4 ± 0.5%) with regard to biocompatibility and biodegradability.     

Thickness and refractive index of DPPC and DPPE monolayers by multiple-beam interferometry

The thickness and refractive index of 1,2-dipalmitoyl-sn-glycero-3-phosphatidyl choline (DPPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) monolayers Langmuir--Blodgett (LB) deposited on mica were measured in dry air and bulk water using multiple-beam interferometry (MBI). Measurements of thickness using atomic force microscopy (AFM) of identical monolayers, and X-ray reflectivity (XRR) of the monolayers on quartz were taken for comparison. The measurement of the properties of solid-supported monolayers in dry air allows lipid optical properties to be determined free from solvent effects. The thickness and refractive index measured by MBI were 25.5?±?0.6 Å and 1.485?±?0.007 for DPPE monolayers, and 23.9?±?0.5 Å and 1.478?±?0.006 for DPPC monolayers in dry air. These thicknesses are consistent with the other techniques used in this work as well as other measurements in the literature. The refractive indices of solid-supported lipid monolayers have not been previously measured. The values are higher than previous measurements on black lipid films done by reflectometry, which is attributed to increased lipid packing density and the absence of hydrocarbon solvents. Applying water to the monolayers had no measurable effect on their properties, indicating that any change in hydration was below detection.

Synthesis,crystal structure,and electrochemical properties of Ni(II) and Cu(II) complexes with two unsymmetrical N2O2 Schiff base ligands

Nickel(II) and copper(II) complexes of two unsymmetrical tetradentate Schiff base ligands [Ni(Me-salabza)] (1), [Cu(Me-salabza)] (2) and [Ni(salabza)] (3), {H₂salabza = N,N′-bis[(salicylidene)-2-aminobenzylamine] and H₂Me-salabza = N,N′-bis[(methylsalicylidene)-2-aminobenzylamine]}, have been synthesized and characterized by elemental analysis and spectroscopic methods. The crystal structures of 2 and 3 complexes have been determined by single crystal X-ray diffraction. Both copper(II) and nickel(II) ions adopt a distorted square planar geometry in [Cu(Me-salabza)] and [Ni(salabza)] complexes. The cyclic voltammetric studies of these complexes in dichloromethane indicate the electronic effects of the methyl groups on redox potential.     

Pseudo‐3D RSSI‐based WSN localization algorithm using linear regression

Receiver Strength Signal Indication based Wireless Sensor Networks offer a cheap solution for location‐aware applications. For a final breakthrough these systems need fast deployment and easy auto‐configuration. In this study, we use the real‐life iMinds test bed to expand a two‐dimensional localization algorithm to the pseudo third dimension with very low additional computational time. Our experiments show that this fast three‐dimensional algorithm has no outliers and avoids manual calibration. Our algorithm has lower position errors than a maximum likelihood algorithm with a mean square error cost function. Furthermore, with non‐parametric statistical tests, we show that our previously designed two‐dimensional preprocessing performs equally well in pseudo‐three dimensions: the preprocessing reduces the position error in a statistically significant way.Copyright © 2013 John Wiley & Sons, Ltd.     

Investigation of Rotating Arc-Catalytic Reactor for CF4 Removal with High Energy Efficiency

Plasma Chemistry and Plasma Processing - CF4 is commonly used in semiconductor industries, and its removal requires a large amount of energy because it is a highly stable perfluorinated compound....     

Chemical Strategies for Dendritic Magneto-plasmonic Nanostructures Applied to Surface-Enhanced Raman Spectroscopy

Chemical analyses in the field using surface-enhanced Raman scattering (SERS) protocols are expected to be part of several analytical procedures applied to water quality monitoring. To date, these endeavors have been supported by developments in SERS substrate nanofabrication, instrumentation portability, and the internet of things. Here, we report distinct chemical strategies for preparing magneto-plasmonic (Fe₃O₄ : Au) colloids, which are relevant in the context of trace-level detection of water contaminants due to their inherent multifunctionality. The main objective of this research is to investigate the role of poly(amidoamine) dendrimers (PAMAMs) in the preparation of SERS substrates integrating both functionalities into single nanostructures. Three chemical routes were investigated to design magneto-plasmonic nanostructures that translate into different ways for assessing SERS detection by using distinct interfaces. Hence, a series of magneto-plasmonic colloids have been characterized and then assessed for their SERS activity by using a model pesticide (thiram) dissolved in aqueous samples.     

In situ and operando electrochemistry of redox enzymes

Understanding the biocatalytic or the interfacial electron transfer processes of redox enzymes is decisive to develop high-performance biofuel cells, mimetic catalysts, bioelectrosynthesis reactors, biosensors, and bioelectronic devices. The state-of-art of redox enzyme electrochemistry lies in using in situ and operando instrumentation, in which protein electrochemistry is resourcefully coupled to or hyphenated with numerous analytical techniques. Nevertheless, there is still a lot to research about the manipulation of redox proteins in the unusual sample holding environments, and bioelectrodes engineering emerges as a key. Here, we discuss these challenges in detail, focusing on contemporary instrumentation setups.     

Poly(Pyridinium Salt)s Containing 2,7-Diamino-9,9′-Dioctylfluorene Moieties with Various Organic Counterions Exhibiting Both Lyotropic Liquid-Crystalline and Light-Emitting Properties

A series of poly(pyridinium salt)s-fluorene main-chain ionic polymers with various organic counterions were synthesized by using ring-transmutation polymerization and metathesis reactions. Their chemical structures were characterized by Fourier Transform Infrared (FTIR), proton (¹H), and fluorine 19 (¹⁹F) nuclear magnetic resonance (NMR) spectrometers. These polymers showed a number-average molecular weight (M_ns) between 96.5 and 107.8 kg/mol and polydispersity index (PDI) in the range of 1.12–1.88. They exhibited fully-grown lyotropic phases in polar protic and aprotic solvents at different critical concentrations. Small-angle X-ray scattering for one polymer example indicates lyotropic structure formation for 60–80% solvent fraction. A lyotropic smectic phase contains 10 nm polymer platelets connected by tie molecules. The structure also incorporates a square packing motif within platelets. Thermal properties of polymers were affected by the size of counterions as determined by differential scanning calorimetry and thermogravimetric analysis measurements. Their ultraviolet-visible (UV-Vis) absorption spectra in different organic solvents were essentially identical, indicating that the closely spaced π-π* transitions occurred in their conjugated polymer structures. In contrast, the emission spectra of polymers exhibited a positive solvatochromism on changing the polarity of solvents. They emitted green lights in both polar and nonpolar organic solvents and showed blue light in the film-states, but their λ_em peaks were dependent on the size of the counterions. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), and their λ_em peaks were blue shifted.     

Observation of competing order in a high-Tc superconductor using femtosecond optical pulses

We present studies of the photoexcited quasiparticle dynamics in Tl(2)Ba(2)Ca(2)Cu(3)O(y) (Tl-2223) using femtosecond optical techniques. Deep into the superconducting state (below 40 K), a dramatic change occurs in the temporal dynamics associated with photoexcited quasiparticles rejoining the condensate. This is suggestive of entry into a coexistence phase which, as our analysis reveals, opens a gap in the density of states (in addition to the superconducting gap), and furthermore, competes with superconductivity resulting in a depression of the superconducting gap.     

Probing the Local Reaction Environment During High Turnover Carbon Dioxide Reduction with Ag-Based Gas Diffusion Electrodes

Discerning the influence of electrochemical reactions on the electrode microenvironment is an unavoidable topic for electrochemical reactions that involve the production of OH⁻ and the consumption of water. That is particularly true for the carbon dioxide reduction reaction (CO₂RR), which together with the competing hydrogen evolution reaction (HER) exert changes in the local OH⁻ and H₂O activity that in turn can possibly affect activity, stability, and selectivity of the CO₂RR. We determine the local OH⁻ and H₂O activity in close proximity to a CO₂-converting Ag-based gas diffusion electrode (GDE) with product analysis using gas chromatography. A Pt nanosensor is positioned in the vicinity of the working GDE using shear-force-based scanning electrochemical microscopy (SECM) approach curves, which allows monitoring changes invoked by reactions proceeding within an otherwise inaccessible porous GDE by potentiodynamic measurements at the Pt-tip nanosensor. We show that high turnover HER/CO₂RR at a GDE lead to modulations of the alkalinity of the local electrolyte, that resemble a 16 m KOH solution, variations that are in turn linked to the reaction selectivity.