Iridescent Colors from Films Made of Polymeric Core-Shell Particles

Summary Brilliant and angle-dependent iridescent colors were obtained from polymer films produced via colloidal crystallization of monodisperse core-shell particles by drying aqueous dispersions. By variation of the particle size, the brilliant color could be varied throughout the visible spectrum. The color effects of the smooth thin films exhibit excellent thermal and water stability. The morphology of the core-shell particles and the properties of the corresponding films were characterized by dynamic light scattering (DLS), atomic force microscopy (AFM), differential scanning calorimetry (DSC), and reflection spectrum measurements. The results indicate that the brilliance of the film is strongly dependent on size and quality of the crystalline domains.     

Zwei eigenartige Ersatzmittel

Ohne ZusammenfassungMitteilung aus dem Staatlichen Chemischen Untersuchungsamt für die Auslandsfleischbeschau in Cleve (Vorsteher: Dr. M. Fritzsche).     

Decohesion Kinetics of PEDOT:PSS Conducting Polymer Films

The highly conductive polymer PEDOT:PSS is a widely used hole transport layer and transparent electrode in organic electronic devices. To date, the mechanical and fracture properties of this conductive polymer layer are not well understood. Notably, the decohesion rate of the PEDOT:PSS layer and its sensitivity to moist environments has not been reported, which is central in determining the lifetimes of organic electronic devices. Here, it is demonstrated that the decohesion rate is highly sensitive to the ambient moisture content, temperature, and mechanical stress. The kinetic mechanisms are elucidated using atomistic bond rupture models and the decohesion process is shown to be facilitated by a chemical reaction between water molecules from the environment and strained hydrogen bonds. Hydrogen bonds are the predominant bonding mechanism between individual PEDOT:PSS grains within the layer and cause a significant loss in cohesion when they are broken. Understanding the decohesion kinetics and mechanisms in these films is essential for the mechanical integrity of devices containing PEDOT:PSS layers and yields general guidelines for the design of more reliable organic electronic devices.     

Conductive Transparent TiNx/TiO2 Hybrid Films Deposited on Plastics in Air Using Atmospheric Plasma Processing

The successful deposition of conductive transparent TiN_x/TiO₂ hybrid films on both polycarbonate and silicon substrates from a titanium ethoxide precursor is demonstrated in air using atmospheric plasma processing equipped with a high‐temperature precursor delivery system. The hybrid film chemical composition, deposition rates, optical and electrical properties along with the adhesion energy to the polycarbonate substrate are investigated as a function of plasma power and plasma gas composition. The film is a hybrid of amorphous and crystalline rutile titanium oxide phases and amorphous titanium nitride that depend on the processing conditions. The visible transmittance increases from 71% to 83% with decreasing plasma power and increasing nitrogen content of the plasma gas. The film resistivity is in the range of ～8.5 × 10¹ to 2.4 × 10⁵ ohm cm. The adhesion energy to the polycarbonate substrate varies from ～1.2 to 8.5 J/m² with increasing plasma power and decreasing plasma gas nitrogen content. Finally, annealing the film or introducing hydrogen to the primary plasma gas significantly affects the composition and decreases thin‐film resistivity.     

Investigation of the SCC behaviour of alloy 2024 using the slow strain rate technique

The stress corrosion cracking (SCC) behaviour of 2024 plate in T351 and T851 tempers was investigated in short transverse direction performing accelerated tests under constant deformation, constant load and slow strain rate conditions. Corrosive media used were: aqueous 3.5% NaCl solution, an aqueous solution of 2% NaCl + 0.5% Na₂CrO₄ at pH 3 (according to LN 65666), an aqueous solution of 3% NaCl + 0.3% H₂O₂, and substitute ocean water according to ASTM D1141. Alternate immersion tests in 3.5% NaCl solution indicated the low SCC resistance of the alloy 2024-T351 as well as the improved SCC behaviour due to aging to T851 condition. Similar results were obtained from constant load tests under permanent immersion conditions in the acidified chloride-chromate solution, in 3% NaCl solution with peroxide, and in substitute ocean water, whereas no SCC failure was observed with specimens which were permanently immersed in 3.5% NaCl solution. Using the slow strain rate method, 3% NaCl + 0.3% H₂O₂ and substitute ocean water were found to be effective synthetic environments. The other two electrolytes did not promote severe stress corrosion cracking with alloy 2024-T351. The SCC behaviour of 2024-T851 was difficult to determine employing the slow strain rate technique. Large scatter in data, observed even in inert environment, and the low elongation of the aged material, exacerbated by a further degradation of ductility due to pitting and intergranular corrosion, precluded an evaluation.     

Heat Treatment and Properties of Nitrogen Alloyed, Martensitic, Corrosion-resistant Steels

This paper gives a short introduction to the typical process route and material properties of these steels in comparison to standard martensitic corrosiun-resistant steels. The typical response of these steels to various heat treatment parameters is shown and explained using the three grades M333, N360 and M340 (all made by Boehler Edelstahl GmbH) as examples, and the physical metallurgy of these steels and its consequences for practical heat treatment is explained. The correlation between tempering parameters and their effect on the toughness and corrosion properties is explained in particular detail, showing that these new steels not only offer far better properly combinations under the usual heat treatment parameters than standard martensitic corrosion-resistant steels, but that they also open the door to extending heat treatment combinations and properties.     

A detailed protocol for the measurement of TGF-beta1 in human blood samples

Bisphosphonates are compounds derived from pyrophosphate, a byproduct of cellular cleavage of adenosine triphosphate (ATP), and are resistant to alkaline phosphatase by virtue of replacement of oxygen by carbon. The high affinity of the P-C-P structure for hydroxyapatite accounts for deposition in bone. Modification of the two side chains of carbon alters the potency of the drugs. Of those that have either completed or are undergoing clinical trials, the order of increasing potency for inhibition of bone resorption is etidronate, clodronate, tiludronate, pamidronate, alendronate, residronate and ibandronate (potency range: 1 to 10,000). Less than 5% of bisphosphonates are absorbed and the half life is a few hours. The drugs must be given on an empty stomach because food and beverages interfere with gastrointestinal absorption. Of the absorbed fraction, as much as 60% is taken up by the skeleton and the remainder is excreted unchanged in the urine. Etidronate, tiludronate, residronate, and alendronate are given orally, clodronate intravenously, and pamidronate and ibandronate by either route. At lower concentrations, bisphosphonates inhibit osteoclatic bone resorption, whereas at higher concentrations they may inhibit mineralization and cause osteomalacia. Inhibition of mineralization diminishes with increasing potency. In postmenopausal women, etidronate and alendronate for 3 yr were shown to inhibit bone resorption, increase bone mineral density (BMD) of the lumbar spine and hip, and prevent fractures without producing osteomalacia. Bone formation also is reduced as a consequence of diminished bone resorption but reduction is less than the reduction of bone resorption. In higher doses bisphosphonates may cause upper gastrointestinal disturbances but in recommended doses they generally are well tolerated and have an excellent safety profile.