Improvement of lysozyme recovery method from the precipitate of protein-anionic surfactant complexes

A new protein separation process using a surfactant and a polar organic solvent consists of a precipitation step and a recovery step. In the precipitation step, a protein-surfactant complex is precipitated from an aqueous solution, when an ionic surfactant, sodium di(2-ethylhexyl) sulfosuccinate (AOT), is added to an aqueous solution, including protein (lysozyme). In the recovery step, the precipitate is dissolved in a polar organic solvent, such as acetone, and the protein is recovered as precipitates when a very small amount of salt solution was added to remove surfactants from the protein-surfactant complex. However, the details of the protein recovery step from precipitate have not been studied yet. In this study, the improvement of the protein recovery step was examined from the viewpoint of a recovery ratio of protein and a remaining ratio of surfactant. The optimum NaCl concentration in the feed for the protein recovery was in the range of 0.05–0.2 kmol/m³. As the NaCl concentration in the feed increased to more than 0.2 kmol/m³, the precipitation ratio decreased due to the electrostatic screening effect of NaCl. It was found that the addition of a very small amount of NaCl solution to acetone was unnecessary when NaCl was included in the feed lysozyme solution. On the other hand, as the NaCl concentration decreased to less than 0.05 kmol/m³, the precipitation ratio was decreased due to the low re-precipitation of protein by the addition of a small amount of NaCl solution in acetone. In the case of the feed containing no salt, the desired NaCl concentration added to acetone was in the range above 0.2 kmol/m³. In addition, the most suitable volume ratio of acetone to feed was found to be 0.2.     

Gas‐separation properties of amine‐crosslinked polyimide membranes modified by amine vapor

The modification of a polyimide (PI) membrane by aromatic amine vapor was performed in this work to increase the crosslinking of the membrane and to study the effect on gas permeability and the corresponding selectivity. The single‐gas permeability of the membranes at 35 °C was probed for H₂, O₂, N₂, CO₂, and CH₄. From the relationship between the combinations of gases and ideal permselectivities, this study showed that amine‐crosslinked PI membranes tended to increase gas permselectivities exponentially with the increasing difference in gas kinetic diameter. Moreover, this study illustrated that the permeability of the membranes was influenced by the formation rate of amine‐crosslinked networks or chemical structures after the reaction. The membranes had the highest level of permselectivities among crosslinked PI membranes for O₂/N₂, and the H₂/CH₄ permselectivity increased 26 times after vapor modification. Furthermore, the modification method that used aromatic amine vapor produced thin and strongly modified layers. These findings indicate that modification is an advantageous technique for improving gas‐separation performance, even considering thinning. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44569.     

A Blend of Ethanol and (−)-α-Pinene were Highly Attractive to Native Siricid Woodwasps (Siricidae,Siricinae) Infesting Conifers of the Sierra Nevada and the Allegheny Mountains

Woodwasps in Sirex and related genera are well-represented in North American conifer forests, but the chemical ecology of native woodwasps is limited to a few studies demonstrating their attraction to volatile host tree compounds, primarily monoterpene hydrocarbons and monoterpene alcohols. Thus, we systematically investigated woodwasp-host chemical interactions in California’s Sierra Nevada and West Virginia’s Allegheny Mountains. We first tested common conifer monoterpene hydrocarbons and found that (?)-α-pinene, (+)-3-carene, and (?)-β-pinene were the three most attractive compounds. Based on these results and those of earlier studies, we further tested three monoterpene hydrocarbons and four monoterpene alcohols along with ethanol in California: monoterpene hydrocarbons caught 72.3% of all woodwasps. Among monoterpene hydrocarbons, (+)-3-carene was the most attractive followed by (?)-β-pinene and (?)-α-pinene. Among alcohols, ethanol was the most attractive, catching 41.4% of woodwasps trapped. Subsequent tests were done with fewer selected compounds, including ethanol, 3-carene, and ethanol plus (?)-α-pinene in both Sierra Nevada and Allegheny Mountains. In both locations, ethanol plus (?)-α-pinene caught more woodwasps than other treatments. We discussed the implications of these results for understanding the chemical ecology of native woodwasps and invasive Sirex noctilio in North America. In California, 749 woodwasps were caught, representing five species: Sirex areolatus Cresson, Sirex behrensii Cresson, Sirex cyaneus Fabricius, Sirex longicauda Middlekauff, and Urocerus californicus Norton. In West Virginia 411 woodwasps were caught representing four species: Sirex edwardsii Brullé, Tremex columba Linnaeus, Sirex nigricornis F., and Urocerus cressoni Norton.     

On the applicability of high strength self‐tapping aluminium bolts in magnesium nut materials for automotive applications

High strength aluminium bolts made of AW 6056 T6, AW 7075 T6 and T79 have been investigated regarding the applicability in magnesium nut materials for automotive applications. With respect to galvanic corrosion all combinations of aluminium bolts with magnesium parts show superior corrosion properties when compared to galvanised steel bolts connected to magnesium. With respect to stress corrosion cracking (SCC) no aluminium bolt in contact with magnesium failed due to SCC. This is because of cathodic protection of aluminium alloy through magnesium. Even peak‐tempered highest strengthened T6 7xxx aluminium bolts can be used for automotive applications when compressive residual stresses are present in the thread root of the bolts.     

Cold repeated forming of compact for aluminium foam

A cold repeated forming process of compacts for producing metal foams was developed in order to strongly bond powder particles. In this process, the compact undergoes severe plastic deformation for the strong bonding of particles by repeated backward extrusion and cup compression, and thus the compact largely foams owing to the accumulation of gas released from blowing agents inside the compact during heating. The cold repeated forming process without heating is much simpler than that for the conventional hot extrusion process. The relative density of the foam was decreased by adding silicon powder to the compact, and an aluminium foam having a relative density of 0.27 was obtained using two repeats of backward extrusion and cup compression, 1.5 mass% titanium hydride powder and 4 mass% silicon powder. In addition, a one-piece foam was successively produced from the bonding of two compacts during the foaming in a die. It was found that the cold repeated forming of compacts is effective for the production of metal foams.     

Corrosion fatigue of a manganese–nitrogen stabilized austenitic stainless steel

Austenitic chromium–manganese–nitrogen stabilized stainless steels have been developed to replace chromium–nickel–nitrogen stainless steels in certain applications. In comparison, chromium–manganese–nitrogen steels have improved mechanical properties and acceptable corrosion resistance in hot, high chloride containing media. In this paper, corrosion fatigue investigations of a solution annealed and for practice more relevant 14% cold worked high alloyed chromium–manganese–nitrogen steel have been done. Inert glycerine was used as reference media and 62% calcium chloride solution as corrosive media, both aerated at a temperature of 120 °C. The stress ratio between upper and lower stress levels was 0.05 (tension–tension loading) to avoid the destruction of the fracture surfaces. As testing frequency for the dynamic experiments, 20 Hz was chosen considering possible application areas. Maximum stress versus number of cycles curves were recorded and representative specimens were investigated in a scanning electron microscope. In addition, electrochemical tests, exposure tests and constant load tests were done. This paper shows results on the corrosion fatigue of a manganese–nitrogen stabilized austenitic steel in a hot high chloride containing salt solution and helps to get a better understanding of occurring failure mechanisms.     

Multi-walled carbon nanotube-reinforced copper nanocomposite coating fabricated by low-pressure cold spray process

Multi-walled carbon nanotube (MWCNT)-reinforced copper (Cu) nanocomposite coatings were successfully deposited on aluminum (Al) substrate by a cold spraying process at a low pressure. The microstructure and the Raman spectrum of the low-pressure-cold-sprayed MWCNT–Cu nanocomposite coating showed that the MWCNTs maintained their tube structure in the Cu matrix, even though structural damage to the MWCNTs increased slightly. MWCNT–Cu nanocomposite-coated Al exhibits higher thermal diffusivity than pure-Cu-coated Al with a comparable hardness. The higher thermal diffusivity of the MWCNT–Cu coating could be explained by the dispersion of MWCNTs within the clean and closed CNT/Cu interfaces, which were achieved with the aid of compressive stress during the cold spraying.     

Fabrication of Translucent Magnesium Aluminum Spinel Ceramics

A precursor for magnesium aluminum spinel powder, composed of crystalline ammonium dawsonite hydrate (NH₄Al(OH)₂CO₃·H₂O) and hydrotalcite (Mg₆Al₂(CO₃)(OH)₁₆·4H₂O) phases, was synthesized via precipitation, using ammonium bicarbonate as the precipitant. The precursor was characterized by differential thermal analysis/thermogravimetry, X-ray diffractometry, and scanning electron microscopy. Reactive spinel powder, which could be densified to translucency under vacuum at 1750°C in 2 h without additives, was obtained by calcining the precursor at 1100°C for 2 h.     

Imaging Secondary-Ion Mass Spectroscopy Observation of the Scavenging of Siliceous Film from 8-mol%-Yttria-Stabilized Zirconia by the Addition of Alumina

The scavenging of a resistive siliceous phase via the addition of Al₂O₃ was studied, using imaging secondary-ion mass spectroscopy (SIMS), given the improved grain-boundary conductivity in 8-mol%-yttria-stabilized zirconia (8YSZ). The grain-boundary resistivity in 8YSZ decreased noticeably with the addition of 1 mol% of Al₂O₃. Strong SiO₂ segregation at the grain boundaries was observed in a SIMS map of pure 8YSZ that contained 120 ppm of SiO₂ (by weight). The addition of 1 mol% of Al₂O₃ caused the SiO₂ to gather around the Al₂O₃ particles. The present observations provided direct and visual evidence of SiO₂ segregation at the grain boundaries (which had a deleterious effect on grain-boundary conductivity) and the scavenging of SiO₂ via Al₂O₃ addition.