Alkoholatkorrosion von Aluminium (EN AC‐48100), Einfluss von Temperatur sowie Ethanol‐ und Wassergehalt

The corrosion behaviour of the aluminium alloy EN AC‐48100 (Al‐17wt%Si‐4wt%Cu‐Mg) was investigated in ethanol fuels with different contents of water (0.05 vol.‐%, 0.2 vol.‐%, 0.35 vol.‐%), at different temperatures (20°C, 60°C, 80°C), and with different contents of ethanol (10 vol.‐%, 25 vol.‐%, 50 vol.‐%, 85 vol.‐%). A interdependency of the corrosion with the temperature and the water content in the fuels was determined. At a temperature of 80°C in an ethanol fuel with less than 0.05 vol.‐% water, strong corrosion starts soon after immersion. An influence of the ethanol content to the degree of corrosion was determined for fuels with ethanol contents below 25 vol.‐% notably. Based on the observations and measurements, a theory for the multi stage character of the corrosion mechanism of aluminium alloys in dry ethanol fuels was developed.     

Electrospray Ionization‐Mass Spectrometry Analysis Reveals Migration of Cyclic Lactide Oligomers from Polylactide Packaging in Contact with Ethanolic Food Simulant

Electrospray ionization‐mass spectrometry analysis revealed rapid migration of cyclic oligomers from polylactide (PLA) packaging when stored in contact with 96% ethanol. The mass losses in contact with water, 3% acetic acid, 10% ethanol and isooctane were 3 to 5 times smaller and no migration of cyclic oligomers was observed. The presence of cyclic oligomers in the original PLA films and their solubility in ethanol, thus, explains the rapid mass loss for PLA in contact with ethanolic food simulant. On prolonged ageing no further mass loss was observed in 96% ethanol, whereas mass loss in aqueous food simulants increased because of hydrolysis of PLA matrix or the cyclic oligomers to water‐soluble linear products. The mass losses were generally somewhat smaller for the stereocomplex material compared with the poly‐l ‐lactide materials. Similar trend was observed for solvent uptakes, which is easily explained by the higher degree of crystallinity and stronger secondary interactions in the stereocomplex material. The use of ethanol as a fatty food simulant for PLA materials could, thus, lead to overestimation of the overall migration values. Copyright © 2012 John Wiley & Sons, Ltd.     

The Influence of High‐pressure Processing on the Migration of Irganox 1076 from Polyethylene Films

This study investigated the influence of high‐pressure processing (HPP) on the migration of Irganox 1076 from low‐density polyethylene films to 10 and 95% ethanol as food simulants. Pouches made from the low‐density polyethylene films were pressured at 600 and 800 MPa for 5 min at 25 and 75 °C. Control samples were not high‐pressure processed. The mass transfer of Irganox 1076 from the films towards the ethanol was monitored over a 40‐day period and quantified using a high‐performance liquid chromatography method. The results showed a lower level of Irganox migration from the films to the ethanol at lower when compared with higher pressure treatments. At the processing temperature of 75 °C, the migration appeared higher when compared with the samples treated at 25 °C. The migration in the HPP samples was higher than that of the controls. The results of this study showed that HPP at higher temperatures caused a higher level of chemical migration from polyethylene when compared with samples not treated by this technique. Copyright © 2013 John Wiley & Sons, Ltd.     

Modulation of Molecular Spatial Distribution and Chemisorption with Perforated Nanosheets for Ethanol Electro‐oxidation

Integrating thermodynamically favorable ethanol reforming reactions with hybrid water electrolysis will allow room‐temperature production of high‐value organic products and decoupled hydrogen evolution. However, electrochemical reforming of ethanol has not received adequate attention due to its low catalytic efficiency and poor selectivity, which are caused by the multiple groups and chemical bonds of ethanol. In addition to the thermodynamic properties affected by the electronic structure of the catalyst, the dynamics of molecule/ion dynamics in electrolytes also play a significant role in the efficiency of a catalyst. The relatively large size and viscosity of the ethanol molecule necessitates large channels for molecule/ion transport through catalysts. Perforated CoNi hydroxide nanosheets are proposed as a model catalyst to synergistically regulate the dynamics of molecules and electronic structures. Molecular dynamics simulations directly reveal that these nanosheets can act as a “dam” to enrich ethanol molecules and facilitate permeation through the nanopores. Additionally, the charge transfer behavior of heteroatoms modifies the local charge density to promote molecular chemisorption. As expected, the perforated nanosheets exhibit a small potential (1.39 V) and high Faradaic efficiency for the conversion of ethanol into acetic acid. Moreover, the concept in this work provides new perspectives for exploring other molecular catalysts.     

Inhibition of microbial growth in ready‐to‐eat food stored at ambient temperature by modified atmosphere packaging

This study was undertaken to develop a modified atmosphere package to control microbial growth in ready‐to‐eat (RTE) products stored at ambient temperature. Ethanol and/or limonene associated with modified atmosphere (CO₂ : O₂ : N₂ = 30% : 5% : 65%) was used to inhibit the growth of total air‐borne microorganisms and Escherichia coli in RTE products stored at 25°C. The results indicated that 0.05% ethanol vapour in the headspace was effective to inhibit the growth of air‐borne microorganisms and E. coli at 25°C for 72 h in a model study, and the effectiveness was related to ethanol content. Both 73 ppm limonene and 0.05% ethanol vapour enhanced the bacteriostatic effect of modified atmosphere in RTE sushi roll products, and no off‐flavour was detected using this formulated gas; however, no significant inhibitory effect was observed for RTE cold noodle products. This study concludes that combinations of carbon dioxide, ethanol or limonene vapours are effective to inhibit microbial growth in RTE food at ambient temperature, and the outcome may be due to the hurdle effect. Copyright © 2003 John Wiley & Sons, Ltd.     

Selective Etching Induced Synthesis of Hollow Rh Nanospheres Electrocatalyst for Alcohol Oxidation Reactions

The hollow noble metal nanostructures have attracted wide attention in catalysis/electrocatalysis. Here a two‐step procedure for constructing hollow Rh nanospheres (Rh H‐NSs) with clean surface is described. By selectively removing the surfactant and Au core of Au‐core@Rh‐shell nanostructures (Au@Rh NSs), the surface‐cleaned Rh H‐NSs are obtained, which contain abundant porous channels and large specific surface area. The as‐prepared Rh H‐NSs exhibit enhanced inherent activity for the methanol oxidation reaction (MOR) compared to state‐of‐the‐art Pt nanoparticles in alkaline media. Further electrochemical experiments show that Rh H‐NSs also have high activity for the electrooxidation of formaldehyde and formate (intermediate species in the course of the MOR) in alkaline media. Unfortunately, Rh H‐NSs have low electrocatalytic activity for the ethanol and 1‐propanol oxidation reactions in alkaline media. All electrochemical results indicate that the order of electrocatalytic activity of Rh H‐NSs for alcohol oxidation reaction is methanol (C₁) > ethanol (C₂) > 1‐propanol (C₃). This work highlights the synthesis route of Rh hollow nanostructures, and indicates the promising application of Rh nanostructures in alkaline direct methanol fuel cells.     

A systematic study on the stability of UV ink photoinitiators in food simulants using GC

Several studies have been published on the stability of plastic monomers and additives in food simulants. However, there are practically no published results about the stability of ink components in food simulants. In this work, the stability of two ultraviolet (UV) ink photoinitiators (PIs) in one aqueous and in two substitute fat food simulants was studied under various time–temperature conditions. Furthermore, the addition of the stabilizing agent hydroquinone monomethyl ester (HQMME) in the same conditions was considered as a comparative experiment. The PIs tested were 1‐hydroxycyclohexyl‐1‐phenyl ketone (Irgacure‐184) and benzyldimethyl ketal (Irgacure‐651). The various test conditions included exposure of 10 days to temperatures of 20, 40 and 60°C for 10% ethanol and 95% ethanol simulants, and exposure of 2 days to temperatures of 20, 40 and 60°C for isooctane. Following exposure to these conditions, the additive samples were analysed. The extracts of samples exposed to various temperature conditions as well as unexposed spiked controls and blanks were analysed by gas chromatography (GC) on a non‐polar (5%‐phenyl)‐methylpolysiloxane capillary column. The results showed that the protective effect of HQMME was not obvious in all test conditions under dark conditions. The Irgacure‐184 was quite stable under all test conditions whether the stabilizing agent was added or not. Irgacure‐651 was stable almost under all test conditions, except in 10% ethanol at 60°C. The mass spectrum of decomposed product of Irgacure‐651 was detected by GC‐MS (Mass Spectrum), and the structure of the decomposed product was obtained by mass spectrographic analysis. The method of detection and disposal is also applicable for UV ink PI migration testing from several different paper or paperboard‐plastic coating layer materials into the food simulants used in the study. Copyright © 2008 John Wiley & Sons, Ltd. 2008     

Ultrathin Vein‐Like Iridium–Tin Nanowires with Abundant Oxidized Tin as High‐Performance Ethanol Oxidation Electrocatalysts

Iridium (Ir) holds great promise for ethanol oxidation reaction (EOR), while its practical applications suffer from the limited shape‐controlled synthesis due to its low‐energy barrier for nucleation. To overcome this limitation, the preparation of a new class of ultrathin vein‐like Ir–tin nanowires (Ir? Sn NWs) with abundant oxidized Sn is reported. By tuning the ratio of Ir to Sn, the optimized Ir₆₇Sn₃₃/C exhibits the highest mass density of 95.6 mA mg^?1 Ir for EOR at low potential (0.04 V), which is 4.1‐fold and 20‐fold higher than that of Ir/C and the commercial Pt/C, respectively. It also exhibits the smallest Tafel slope of 153 mV dec^?1 and superior stability after 2 h chronoamperometric measurement. Electrochemical measurements and X‐ray photoelectron spectra results confirm that the abundant oxidized Sn promotes a complete oxidization of ethanol into CO₂ at low potential. This work highlights the importance of non‐noble metal on enhancing the EOR performance.     

Mesoporous Block‐Copolymer Nanospheres Prepared by Selective Swelling

Block‐copolymer (BCP) nanospheres with hierarchical inner structure are of great interest and importance due to their possible applications in nanotechnology and biomedical engineering. Mesoporous BCP nanospheres with multilayered inner channels are considered as potential drug‐delivery systems and templates for multifunctional nanomaterials. Selective swelling is a facile pore‐making strategy for BCP materials. Herein, the selective swelling‐induced reconstruction of BCP nanospheres is reported. Two poly(styrene‐block‐2‐vinylpyridine) (PS‐b‐P2VP) samples with different compositions (PS₂₃₆₀₀‐b‐P2VP₁₀₄₀₀ and PS₂₇₇₀₀‐b‐P2VP₄₃₀₀) are used as model systems. The swelling reconstruction of PS‐b‐P2VP in ethanol, 1‐pyrenebutyric acid (PBA)/ethanol, or HCl/ethanol (pH = 2.61) is characterized by scanning electron microscopy and transmission electron microscopy. It is observed that the length of the swellable block in BCP is a critical factor in determining the behavior and nanostructures of mesoporous BCP nanospheres in selective swelling. Moreover, it is demonstrated that the addition of PBA modifies the swelling structure of PS₂₃₆₀₀‐b‐P2VP₁₀₄₀₀ through the interaction between PBA and P2VP blocks, which results in BCP nanospheres with patterned pores of controllable size. The patterned pores can be reversibly closed by annealing the mesoporous BCP nanospheres in different selective solvents. The controllable and reversible open/closed reconstruction of BCP nanospheres can be used to enclose functional nanoparticles or drugs inside the nanospheres. These mesoporous BCP nanospheres are further decorated with gold nanoparticles by UV photoreduction. The enlarged decoration area in mesoporous BCP nanospheres will enhance their activity and sensitivity as a catalyst and electrochemical sensor.     

2D PdAg Alloy Nanodendrites for Enhanced Ethanol Electroxidation

The development of highly active and stable electrocatalysts for ethanol electroxidation is of decisive importance to the successful commercialization of direct ethanol fuel cells. Despite great efforts invested over the past decade, their progress has been notably slower than expected. In this work, the facile solution synthesis of 2D PdAg alloy nanodendrites as a high‐performance electrocatalyst is reported for ethanol electroxidation. The reaction is carried out via the coreduction of Pd and Ag precursors in aqueous solution with the presence of octadecyltrimethylammonium chloride as the structural directing agent. Final products feature small thickness (5–7 nm) and random in‐plane branching with enlarged surface areas and abundant undercoordinated sites. They exhibit enhanced electrocatalytic activity (large specific current ) and excellent operation stability (as revealed from both the cycling and chronoamperometric tests) for ethanol electroxidation. Control experiments show that the improvement comes from the combined electronic and structural effects.     

Hybrid Organic–Inorganic Colloidal Composite ‘Sponges’ via Internal Crosslinking

An effective method for the generation of hybrid organic–inorganic nanocomposite microparticles featuring controlled size and high structural stability is presented. In this process, an oil‐in‐water Pickering emulsion is formed using hydrophilic amine‐functionalized silica nanoparticles. Covalent modification using a hydrophobic maleic anhydride copolymer then alters nanoparticle wettability during crosslinking, causing a core‐shell to nanocomposite structural reorganization of the assemblies. The resulting porous nanocomposites maintain discrete microparticle structures and retain payloads in their oil phase even when incubated in competitive solvents such as ethanol.     

Ethanol combined with heparin as a locking solution for the prevention of catheter related blood stream infections in hemodialysis patients: A prospective randomized study

Introduction: Ethanol lock solution has been mainly administered in paediatric and home parenteral nutrition patients in order to prevent catheter related blood stream infections (CRBSI). Its utility in hemodialysis (HD) patients with non‐tunneled‐uncuffed catheter (NTC) has been poorly explored. Methods: We conducted a prospective randomized study in chronic HD patients requiring a newly inserted NTC‐while awaiting for the maturation of an already established arteriovenous fistula (AVF) or arteriovenous graft (AVG) or tunneled‐cuffed catheter insertion. Patients were randomized in two groups: Group A, where the lock solution was ethanol 70% + unfractionated heparin 2000 U/mL and group B, that received only unfractionated heparin 2000 U/mL. Primary end point was CRBSIs whereas exit site infections, thrombotic and bleeding episodes were the secondary end points. Findings: One hundred three HD patients were enrolled in the study (group A, n = 52; group B, n = 51). The median number of catheter days was 32 for group A (range: 23–39) and 34 (range: 27–40) for group B with no statistically significant difference between the two groups. Group A (ethanol + heparin) demonstrated 4/52 episodes (7.69%) of CRBSI whereas Group B (heparin) 11/51 episodes (21.57%) (P = 0.04). CRBSI rates per 1000 catheter days were 2.53/1000 catheter days for group A and 6.7/1000 catheter days for group B (P = 0.04). Mean cumulative infection‐free catheter survival in the ethanol group did not differ significantly compared to the heparin group (log‐rank test = 2.99, P = 0.08). Thrombotic episodes did not differ between the two groups. Discussion: Locking of NTCs in HD patients with ethanol 70% + unfractionated heparin reduces CRBSI rates without increasing the thrombotic episodes.     

Chromogenic Photonic Crystal Sensors Enabled by Multistimuli‐Responsive Shape Memory Polymers

Here novel chromogenic photonic crystal sensors based on smart shape memory polymers (SMPs) comprising polyester/polyether‐based urethane acrylates blended with tripropylene glycol diacrylate are reported, which exhibit nontraditional all‐room‐temperature shape memory (SM) effects. Stepwise recovery of the collapsed macropores with 350 nm diameter created by a “cold” programming process leads to easily perceived color changes that can be correlated with the concentrations of swelling analytes in complex, multicomponent nonswelling mixtures. High sensitivity (as low as 10 ppm) and unprecedented measurement range (from 10 ppm to 30 vol%) for analyzing ethanol in octane and gasoline have been demonstrated by leveraging colorimetric sensing in both liquid and gas phases. Proof‐of‐concept tests for specifically detecting ethanol in consumer medical and healthcare products have also been demonstrated. These sensors are inexpensive, reusable, durable, and readily deployable with mobile platforms for quantitative analysis. Additionally, theoretical modeling of solvent diffusion in macroporous SMPs provides fundamental insights into the mechanisms of nanoscopic SM recovery, which is a topic that has received little examination. These novel sensors are of great technological importance in a wide spectrum of applications ranging from environmental monitoring and workplace hazard identification to threat detection and process/product control in chemical, petroleum, and pharmaceutical industries.     

DLC‐coated pure bioplastic foil

Polymers made of renewable resources increasingly replace conventional plastic materials made of petroleum. Socalled bioplastics can be found e. g. in food industry, for agricultural usage or in the medical field. The range of applications can be further expanded with specialized coating of their surface. Especially in case of food packaging and the usage within medical devices as well as the storage of these composite materials, sterilization or at least the partial reduction of microbial growth is an important issue which needs to be addressed early in the production process. In this work, a commercially available polyhydroxyalkanoate (PHA) pure bioplastic foil of 50 μm thickness was coated with 100 nm of diamond‐like carbon (DLC) and afterwards treated by four different standard methods of sterilization and / or disinfection, namely deep‐freezing, ultraviolet irradiation, autoclaving and immersion in ethanol. The surface morphology of treated DLC‐coated and uncoated samples was investigated and compared to the untreated DLC‐coated and uncoated samples using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Measurements exhibited damage of the composite for autoclaved and in ethanol immersed samples, whereas deep‐frozen and ultraviolet irradiated samples showed no structural changes. These findings clearly demonstrate deep‐freezing and ultraviolet irradiation to be appropriate methods for the disinfection and sterilization, respectively, of the DLC‐coated pure bioplastic foil.     

Tuning Surface Structure of 3D Nanoporous Gold by Surfactant‐Free Electrochemical Potential Cycling

3D dealloyed nanoporous metals have emerged as a new class of catalysts for various chemical and electrochemical reactions. Similar to other heterogeneous catalysts, the surface atomic structure of the nanoporous metal catalysts plays a crucial role in catalytic activity and selectivity. Through surfactant‐assisted bottom‐up synthesis, the surface‐structure modification has been successfully realized in low‐dimensional particulate catalysts. However, the surface modification by top‐down dealloying has not been well explored for nanoporous metal catalysts. Here, a surfactant‐free approach to tailor the surface structure of nanoporous gold by surface relaxation via electrochemical redox cycling is reported. By controlling the scan rates, nanoporous gold with abundant {111} facets or {100} facets can be designed and fabricated with dramatically improved electrocatalysis toward the ethanol oxidation reaction.     

Chiral Responsive Liquid Quantum Dots

How to convert the weak chiral‐interaction into the macroscopic properties of materials remains a huge challenge. Here, this study develops highly fluorescent, selectively chiral‐responsive liquid quantum dots (liquid QDs) based on the hydrophobic interaction between the chiral chains and the oleic acid‐stabilized QDs, which have been designated as (S)‐1810‐QDs. The fluorescence spectrum and liquidity of thermal control demonstrate the fluorescence properties and the fluidic behavior of (S)‐1810‐QDs in the solvent‐free state. Especially, (S)‐1810‐QDs exhibit a highly chiral‐selective response toward (1R, 2S)‐2‐amino‐1,2‐diphenyl ethanol. It is anticipated that this study will facilitate the construction of smart chiral fluidic sensors. More importantly, (S)‐1810‐QDs can become an attractive material for chiral separation.     

Surfactant‐Concentration‐Dependent Shape Evolution of Au–Pd Alloy Nanocrystals from Rhombic Dodecahedron to Trisoctahedron and Hexoctahedron

The surface structure‐controlled synthesis of noble metal nanocrystals (NCs) bounded by high‐index facets has become a hot research topic due to their potential to significantly improve catalytic performance. This study reports the preparation of monodisperse Au–Pd alloy NCs with systematic shape evolution from rhombic dodecahedral (RD) to trisoctahedral (TOH), and hexoctahedral (HOH) structures by varying the concentration of surfactant in the surfactant‐mediated synthesis. The as‐prepared three kinds of alloy NCs possess almost the same size and composition as each other. It is suggested that the surfactant containing long‐chain octadecyltrimethyl ammonium (OTA⁺) ions plays a key role in the formation of high index facets, and the crystal growth kinetics may also have an effect on the formation of different nanocrystal morphologies. In addition, the catalytic activities of these NCs are evaluated by structure‐sensitive reactions, including ethanol electro‐oxidation and the catalytic reduction of 4‐nitrophenol (4‐NPh). These three types of Au–Pd alloy NCs exhibit different catalytic selectivities towards these two reactions. The catalytic activities toward electro‐oxidation of ethanol are in the order of HOH > RD > TOH, which follows the order of their corresponding surface energies. However, the activities toward catalytic reduction of 4‐NPh are in the order of RD > TOH > HOH, which should be related to the local structure of the surfaces.     

Korrosion durch Biokraftstoffe – Schutz durch Beschichtungen auch bei zyklischer Beanspruchung

Corrosion by biofuels ‐ Protection by coatings also under cyclic loadings The influence of corrosion on fatigue design must be considered in numerous component parts in the automotive industry. By using appropriate coatings the negative influence of corrosion under static and cyclic loading can be suppressed. Using the aluminum cast alloy AlSi7Mg0,3 T6 as an example, selected material‐coating‐systems were to be characterized under mechanical‐thermal‐corrosive complex loadings and characteristic properties for the fatigue design under cyclic loadings were to be determined. Conditioning tests were carried out with uncoated, anodized and chemical‐nickel‐plated specimen at different temperatures in the media fuel E5 (fuel with 5 % ethanol added) and E10 (fuel with 10 % ethanol added) and followed by SEM examined. The cyclic fatigue tests with chemically‐nickel‐plated and tempered aluminum in the fuel E5 at 100 °C no reduced influence on the fatigue strength, within the scattering, was discerned. This result agrees with the conditioning tests in the fuel E5 at 100 °C, where no corrosion was observed. Despite the coating of the specimens salt spray fog leads to a clear reduction in the fatigue strength. Using a damage accumulation calculation, it could be shown, that the real damage sum of the callipers and specimens, despite different types of coating, are comparable.     

Low temperature direct electroless nickel plating on silicon wafer

Abstract

In the study of electroless nickel (EN) plating on n‐type (100) silicon wafers, a relatively low‐temperature alkaline plating process is developed. Further experiments show that simple ethanol pretreatment of the substrate is practicable for obtaining an EN layer with a good adhesion strength of about 9.8 to 14.7 MPa. Both sodium tungstate and sodium fluoride can be used to decrease the threshold plating temperature from near 80°C to 65°C. The phosphorous content of the as‐plated layer is slightly higher than 7 wt.%.     

Korrosionsverhalten unterschiedlicher Aluminiumlegierungen in ethanolhaltigem Ottokraftstoff unter erhöhten Temperaturen

Corrosion behaviour of different aluminium alloys in fuels containing ethanol under increased temperatures In the face of running short the natural resources of petroleum and in consequence of the Kyoto‐Protocol, there is a change in the general political conditions. For this reason, fuel components of biogenous origin (such as ethanol or biodiesel) used as blends to conventional fuels are moving into focus. These blends can cause a change to the characteristics of the fuels. At first it was assumed, that a blend of ethanol to fuel does not have a particularly strong effect on the corrosion behaviour of lightweight construction materials. Samples made of aluminium materials with strong reference to practice, exposed to a blend of 10 % ethanol and test fluid under increased pressures and temperatures, showed at higher temperatures (T = 130 °C ‐ e.g. close to the engine used components) already after a short period strong corrosion ‐ dry corrosion. By means of the accomplished research, substantial influencing variables on the corrosion behaviour of aluminium materials in fuels blended with ethanol could be pointed out.