The effect of climate variations on glulam—an experimental study

Climate variations affect timber structures by causing moisture induced stresses which may lead to cracks in timber members. The paper presents experimentally determined moisture induced stresses that arise perpendicular to the grain of glulam specimens during exposure to 1-dimensional drying and wetting. Although to a certain extent reduced by creep effects, the determined tensile stresses can significantly exceed the characteristic tensile strength of glulam. Additional measurements of moduli of elasticity (E) and hygroexpansion coefficients (α) revealed that these parameters are strongly affected by the geometrical configuration (pith locations) of the specimens. By means of all the parameters determined here, it can be avoided that parameters have to be selected from different literature sources, which introduces large uncertainties into the numerical simulations.     

Prediction of plastic surface defects for 5-axis ball end milling of Ti-6Al-4 V with rounded cutting edges using a material removal simulation

The resulting surface quality after 5-axis ball end milling is of superior importance because finish milling is often the last process step determining the functional performance of a component. However, the prediction of surface topography is still a challenging task. Especially in ball end milling with the characteristic sickle shaped chip cross section, ploughing effects in the area of low chip thickness result in plastic deformation and surface defects (also known as burr). This paper provides a new approach to predict those surface defects by considering the minimum chip thickness for complex milling engagement conditions within a virtual process design. This allows the choice of suitable process parameters without extensive experimental efforts.     

Microparticles based on hydrophobically modified chitosan as drug carriers

In this work, a hydrophobically modified (HM) chitosan derivative was prepared by covalent linkage of C₁₂ groups to the chitosan backbone. HM‐chitosan microparticles were prepared according to an emulsification‐solvent evaporation method and naltrexone (NTX) was used as a model drug. For comparison, unmodified chitosan and poly lactic‐co‐glycolic acid (PLGA) microparticles were also tested as carriers for NTX. HM‐chitosan formed viscous semi‐dilute solutions, suggesting a high level of chain entanglements and hydrophobic associations. HM‐chitosan microparticles generally showed higher production yield and encapsulation efficiency, as compared with chitosan and PLGA. The burst release shown by chitosan microparticles was significantly reduced when using the HM‐chitosan derivative. An enhanced control of drug release was observed over at least 50 days. PLGA particles demonstrated inferior controlled release properties as compared to HM‐chitosan subsequent to the initial release stage. These results revealed the potential of hydrophobic modification of chitosan as a means to improve the stability and sustained delivery properties of the polymer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40055.     

Impact of the solidification path of FeOx–SiO2 slags on the resultant inorganic polymers

Aiming to reduce the carbon dioxide emissions associated with cement production, alternative binders such as inorganic polymers currently receive substantial attention and slags from the non-ferrous metallurgy are promising precursors. However, studies  that correlate their chemistry and crystallinity with the newly formed binder remain limited. In this work, the effect of three different solidification methods on glass formation and reactivity of FeO_x–SiO₂ slags, as well as on the molecular structure of the resultant Fe-rich inorganic polymers, was investigated. The inorganic polymers were synthesized by mixing the slags (approximate molar ratio FeO/SiO₂ = 1.6) with an alkali silicate solution (molar ratios SiO₂/Na₂O = 1.6 and H₂O/Na₂O = 25). Results demonstrated that higher cooling rates promoted higher glass formation and faster reaction kinetics when the slags were activated. ⁵⁷Fe Mössbauer spectroscopy indicated that all the slags consisted predominantly of Fe²⁺ ions with a minor amount of Fe³⁺ ions, regardless of the variability in glass content. The binder phase of all inorganic polymers consisted of iron in both Fe²⁺ and Fe³⁺ states, after 28 days of curing. After pulverizing the inorganic polymer pastes and exposing the powder to air for 28 additional days, the Fe²⁺ state in the binder transformed to Fe³⁺. The compressive strength evolution of the three slags showed that the 2-day strength was higher for the samples with a higher amorphous fraction, while after 28 days, this influence was less pronounced.     

Inorganic polymers made of fayalite slag: On the microstructure and behavior of Fe

The microstructure of inorganic polymers (IP) formed from fayalite slag was investigated as a function of the composition of different activating solutions. The starting slag was 80 wt% amorphous, and after activation using sodium silicate solutions with varying SiO₂/Na₂O molar ratios, the amorphous phase dissolved and a binder phase was formed. The morphology of this binder, including the population and size of remnant particles and pores, was dependent on the particular activating solution used, and became denser as the level of silicate rose. ⁵⁷Fe Mössbauer spectroscopy revealed that the IP synthesis reaction is combined with the oxidation of Fe²⁺ from the fayalite slag to Fe³⁺ in the inorganic polymer binder. The reaction extent varied and could be quantified using the absorption areas of these ions. Data corroborate that the Fe²⁺ ions in the amorphous part of the fayalite slag and the Fe³⁺ ions in the new binder phase had an average oxygen‐coordination number of 5.     

Oxides of copper, ceria promoted copper, manganese and copper manganese on Al2O3 for the combustion of CO, ethyl acetate and ethanol

Combustion of CO, ethyl acetate and ethanol was studied over CuO_x/Al₂O₃, CuO_x–CeO₂/Al₂O₃, CuMn₂O₄/Al₂O₃ and Mn₂O₃/Al₂O₃ catalysts. It was found that modification of the alumina with ceria before subsequent copper oxide deposition increases the activity for combustion of CO substantially, but the effect of ceria was small on the combustion of ethyl acetate and ethanol. The activity increases with the CuO_x loading until crystalline CuO particles are formed, which contribute little to the total active surface. The CuO_x–CeO₂/Al₂O₃ catalyst is more active than the CuMn₂O₄/Al₂O₃ catalyst for the oxidation of CO but the CuMn₂O₄/Al₂O₃ catalyst is more active for the combustion of ethyl acetate and ethanol.

Thermal ageing and water vapour in the feed caused a modest decrease in activity and did not affect the CuO_x–CeO₂/Al₂O₃ and CuMn₂O₄/Al₂O₃ catalysts differently. In addition, no difference in intermediates formed over the two catalysts was observed.

Characterisation with XRD, FT-Raman and TPR indicates that the copper oxide is present as a copper aluminate surface phase on alumina at low loading. At high loading, bulk CuO crystallites are present as well. Modification of the alumina with ceria before the copper oxide deposition gives well dispersed copper oxide species and bulk CuO crystallites associated to the ceria, in addition to the two copper oxide species on the bare alumina. The distribution of copper species depends on the ceria and copper oxide loading. The alumina supported copper manganese oxide and manganese oxide catalysts consist mainly of crystalline CuMn₂O₄ and Mn₂O₃, respectively, on Al₂O₃.     

Lactational response to soybean meal, heated soybean meal, and extruded soybeans with ruminally protected methionine

Seventy-three high producing Holstein cows were arranged in a 3 X 2 factorial to evaluate three protein supplements (soybean meal, heat-treated soybean meal, and extruded blend of soybeans and soybean meal) without or with 15 g/head/d of ruminally protected DL-methionine during wk 4 through 16 postpartum. Total mixed diets contained (DM basis) 30% corn silage, 15% alfalfa hay, and 55% of the respective concentrate mix. Milk production was higher when cows were fed either heated soybean product instead of soybean meal. Methionine supplementation increased production when fed with soybean meal (32.2 and 33.8 kg/d) but not when fed with heat-treated soybean meal (34.5 and 33.0 kg/d) or extruded soybeans (36.2 and 34.4 kg/d). Milk fat percentages were lower with extruded soybeans (3.01, 2.93, and 2.66) and were similar without (2.83) or with (2.90) supplemental methionine. Milk protein percentages were highest when fed soybean meal, lowest with extruded soybeans (3.02, 2.92, and 2.87), and higher with supplemental methionine (2.91 and 2.96). Dry matter intake was higher when fed supplemental methionine (20.0 and 21.3 kg/d). Production of milk in early lactation high producing dairy cows was increased by supplementing a soybean meal diet with ruminally protected methionine or by replacing the soybean meal with heat-treated soybean meal, soybeans, or a mixture of the two.     

Effect of crude oil ageing on low salinity and low salinity surfactant flooding

Injection of brine with lower salinity than the connate brine has proven to give a moderate increase in oil recovery in sandstones. Recent research has shown that this process will significantly benefit from introducing surfactant optimised for low salinity environment.The mechanisms underlying increased recovery by low salinity brine injection are not yet fully understood. However, research to date suggests that they are related to complex crude oil/brine/rock interactions. With this in mind, the present paper investigates primarily how the extent of oil recovery from Berea sandstones subjected to long term exposure of crude oil is influenced by (1) low salinity water injection and (2) combined process low salinity water injection with surfactant flooding.Core displacement tests were conducted on four Berea cores (30 cm), two in a natural state and two that had been subject to extensive crude oil ageing at high temperature. Results obtained from different flooding steps are discussed in terms of oil recovery and effluent properties including turbidity, pH- and ion analysis (Na⁺, Mg²⁺, Ca²⁺). The results effectively illustrate that oil recoveries from the aged cores are higher during both low salinity water injection and low salinity water injection combined with surfactant flooding. An assessment of how tertiary oil recovery in aged and unaged cores varies with surfactant concentration is also presented.Effluent ion analysis from low salinity water floods showed that Mg²⁺ ions were strongly retained in the aged core while Ca²⁺ ions were being produced from both aged and unaged cores. The latter was attributed mainly to calcite dissolution. Results obtained from pressure profiles, effluent ion analysis and turbidity tests suggest higher production and elution of fine particles from the unaged core.     

Blends of Two Perylene Derivatives: Mesogenic Properties and Application As Emitter Materials in OLEDs

Blends consisting of two components, namely a liquid crystalline perylene ester and a bilaterally extended perylene ester, were studied. The liquid crystalline properties of these blends were investigated in detail by means of polarized optical microscopy and differential scanning calorimetry. The resulting phase diagram was used to explore the potential of these blends as emitter layers in OLEDs, which were prepared via thermal evaporation in a vacuum and spin coating of solutions.