The article contains sections titled: 1. Introduction 2. Properties 2.1. Physical Properties 2.2. Chemical Properties 3. Production 3.1. Acrolein by Propene Oxidation 3.2. Methacrolein 4. Quality and Analysis 5. Handling, Storage, and Transportation 6. Uses and Production Data 7. Toxicology and Ecotoxicology 7.1. Toxicology 7.2. Ecotoxicology Acrolein is the simplest unsaturated aldehyde. It is an important intermediate in the production processes of a variety of substances. The main use of isolated acrolein is in the production of d,l ‐methionin, but in far more production processes, acrolein is used without purification. Acrolein is an extremely reactive chemical and, in very low concentrations, acts as a very effective broad‐spectrum biocide. Methacrolein is produced commercially as an organic intermediate, which is used as building block for chain expansions or, in limited application, in the synthesis of flavors and fragrances.
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We introduced a NiFe/antiferromagnetic–MnIr bilayer or a NiFe/MnIr/NiFe trilayer below a CoTaZr soft magnetic underlayer in perpendicular recording media as a way of controlling the magnetic domain structure of the soft magnetic underlayer, and we investigated the effect of exchange biasing on the spike noise. Samples consisting of a layer structure—NiFe (5 nm thick)/MnIr (2.5–50 nm)/NiFe (5 nm)/CoTaZr (50–200 nm)—were sputter deposited on precoated glass disks. The samples were heated with a lamp heater and cooled in a magnetic field along the radial direction of the disk. Both uniaxial and unidirectional anisotropies were induced along the magnetic field when the thickness of the MnIr layer was more than 5 nm. The first NiFe layer promoted a fcc–MnIr (111) crystalline texture, while the second NiFe layer enhanced the value of exchange-bias field by about 20%. The exchange-bias field increased from 6 to 24 Oe as the CoTaZr-layer thickness decreased from 200 to 50 nm. Many spikes along the radial direction were observed for a 100-nm-thick CoTaZr single-layer film, while no remarkable spikes were observed for a NiFe/MnIr/NiFe/CoTaZr (100 nm) film. It was found that the NiFe/MnIr/NiFe trilayer restrained the formation of domain walls in the CoTaZr layer, thereby reducing the spike noise.
Poly(styrene) microcapsules, prepared by depositing the polymer around emulsified aqueous droplets, were coated with a synthesized polyelectrolyte; i.e., copolymer of maleic acid (MA) with methyl vinyl ether (MVE), co-poly(MA, MVE), or with styrene (St), copoly(Ma, St). The permeability of the capsule membrane was investigated under various pHs of the outer medium using n-propyl alcohol as a permeant. It became apparent that either copoly(MA, St)- or copoly(MA, MVE)-coated microcapsules function as a pH-sensitive capsule. In particular, the former showed a dramatic change of the permeability in response to small differences in pH (5-6). By reference to the viscometric and electrophoretic studies of both copolymers, these were interpreted as being due to a pH-induced alteration of the configuration of the copolymer coating on the surface of the capsule membrane. When sucrose was hydrolyzed in an aqueous suspension of the copoly(MA, St)-coated capsules into which invertase was loaded, the hydrolytic reaction was initiated at pH 5. 5 and stopped at pH 4. 5. Such initiation-cessation control was repeated reversibly without damaging the capsules.
Calcium alginate gel stabilized with a polyelectrolyte complex (PEC) consisting of potassium poly(vinyl alcohol) sulfate (KPVS) and trimethylammonium glycol chitosan iodide (TGCI) was used for the immobilization of beta-amylase. The immobilization was made by gelling aqueous droplets of enzyme solution including both sodium alginate and KPVS in a CaCl(2) solution containing TGCI. The activity of the enzyme entrapped into the stabilized gel beads was evaluated by studying the batch reaction kinetics of enzyme-catalyzed hydrolysis of maltotetraose. Repeated kinetic measurements, totaling 18, were carried out at fixed time intervals. After each measurement the beads were stirred for 1 day in a freshly prepared 10 mM NaCl solution at 3 degrees C. It was found that the immobilized system remained stable without leading to a serious loss of the activity or to a large leakage of the enzyme from the support. This was explained as being due to a PEC-crosslinked contracted network structure of the stabilized gel matrix.
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