Magnetic properties of ferrocenylmethylacrylate-N-dodecylacryl-amide copolymer Langmuir–Blodgett films

Langmuir–Blodgett (LB) films of the copolymer with ferrocenyl-methyl-acrylate (FcMA) and N-dodecyl-acrylamide (DDA) were fabricated. The magnetic moment of these LB films became about twenty times larger than that of the powder. In addition, the LB films had a magnetic anisotropy depending on the dipping direction. The FTIR results suggested that the polymer chains in the LB films were preferably aligned with the perpendicular of the dipping direction. These results were discussed by the intermolecular electron transfer.     

Study on the thermal decomposition of NaBH4 catalyzed by ZrCl4

The catalytic effect of zirconium tetrachloride (ZrCl₄) on the thermal dehydrogenation of NaBH₄ has been studied. The ZrCl₄ reduced to ZrCl₂ and metallic zirconium which exhibit the high catalytic activity during thermal dehydrogenation. The activation energy corresponding to dehydrogenation of NaBH₄ is remarkably reduced to 180 kJ/mol in the presence of a catalyst as compared to pure-NaBH₄ which was found to be 275 kJ/mol under the similar experimental conditions. The reduced activation energy leads to decreased onset dehydrogenation temperature (<300 °C). A substantial amount of sodium remained at the end of the dehydrogenation of catalyzed sample. The low-temperature dehydrogenation of catalyzed NaBH₄ could be useful to manage the evaporation of sodium metal.     

High-pressure synthesis and optical limiting property of cyclic diphenylacetylene oligomer

New conjugated oligomers were synthesized by reacting diphenylacetylene under high pressure of 0.13–0.76 GPa at 250 and 300°C for 1–10 h. The number-average molecular weight M _n, and the weight-average molecular weight M _w increased with pressure, but those values were independent of temperature and time (M _n, 320–490; M _w, 350–580). Elementary analysis, field desorption mass spectrometry, Fourier transform infrared, and ¹³C nuclear magnetic resonance experiments revealed that the oligomer above and including pentamer was a new compound having cyclic structure. Toluene solutions of the oligomer (400 M _n) contained within a quartz cell were irradiated with the pulse from a frequency-doubled Nd : Yag laser at 532 nm. The transmittance of the solution decreased with input fluence, and we observed an optical limiting property with saturated output fluence. As the concentration of the oligomer increased, the saturated output fluence decreased. The optical limiting property was analyzed according to the reverse saturable absorption mechanism. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:129–135, 1998     

High‐pressure synthesis of cyclic mesitylacetylene oligomer

Reaction of mesitylacetylene was carried out by annealing under high pressure (0.13 and 0.52 GPa). The products obtained were classified into soluble and insoluble products in chloroform. The insoluble product reacted under 0.13 GPa was the mesitylacetylene polymer. The soluble product reacted under 0.13 GPa was classified as the monomer and the oligomer [number‐average molecular weight (M̄_n): 390, weight‐average molecular weight (M̄_w): 453, Oligomer yield (O_y): 36%]. The oligomer yield was accelerated by pressure [pressure: 0.13–0.52 GPa, M̄_n: 390–315, M̄_w: 453–968, O_y: 36–98%]. Field desorption mass spectrum showed that the oligomer had cyclic structure. The result of the elementary analysis revealed that the insoluble product reacted under 0.52 GPa was a polycyclic aromatic compound. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1539–1542, 1999     

Preservative effect of combined treatment with electrolyzed NaCl solutions and essential oil compounds on carp fillets during convectional air-drying

The antimicrobial and antioxidant effects on carp fillet samples of treatments with alkaline electrolyzed NaCl solution EW (-) prior to treatment with acidic electrolyzed NaCl solution EW (+) and 1% solutions of the essential oils consisting of 0.5% carvacrol and 0.5% thymol (1% Cv+Ty) were tested. First carp fillet samples were treated with EW (-), then EW (+), followed by 1% (C+T), represented as [EW (-)/EW (+)/1% (Cv+Ty)] for 15 min, during drying at 45 degrees C. Samples were subsequently evaluated by microbiological, chemical and sensory analyses. Microbiological analyses indicated that the initial total microbial counts of samples treated with EW (-)/EW (+), 1% (Cv+Ty) or EW (-)/EW (+)/1% (Cv+Ty) were significantly (p< or =0.05) reduced, compared with the control sample. Treatment with EW (-)/EW (+)/1% (Cv+Ty) gave the strongest overall inhibition of microbial growth when compared to all of the other treatments. The volatile basic nitrogen (VBN) value of samples treated with EW (-)/EW (+)/1% (Cv+Ty) was kept at low level (18.46+/-0.45) until the end of drying period (5 days), compared with control samples (40.33+/-0.58). Treatment with EW (-)/EW (+)/1% (Cv+Ty) during drying significantly reduced the peroxide values (PV) and thiobarbituric acid values (TBA). Sensory evaluation indicated that there were significant differences (p< or =0.05) in the color, odor, taste, flavor and texture, on the end of the 5-day drying period between samples treated with EW (-)/EW (+)/1% (Cv+Ty), as compared to all of the other treatments. We conclude that treatment with EW (-)/EW (+)/1% (Cv+Ty) had stronger antimicrobial and antioxidant effects than all of the other treatments on carp fillets during drying, and could be a good alternative to artificial preservatives in food industry.     

10 micrometer-scale SPM local oxidation lithography

10 micrometer-scale scanning probe microscopy (SPM) local oxidation lithography was performed on Si. In order to realize large-scale oxidation, an SPM tip with a contact length of 15 microm was prepared by focused-ion-beam (FIB) etching. The oxidation was carried out in contact mode operation with the contact force ranging from 0.1 to 2.1 microN. The applied bias voltage was 50 V, and scanning speed was varied from 10 to 200 microm/s. The scan length was 15 microm for one cycle. The influence of contact force on the large-scale oxidation was investigated. At high contact force, the Si oxide with good size uniformity was obtained even with high scanning speed. The SPM tip with larger contact length may increase the spatial dimensions of the water meniscus between the SPM tip and sample surface, resulting in the larger dimensions of the fabricated oxide. Furthermore, the throughput of large-scale oxidation reached about 10(3) microm2/s by controlling the scanning speed and contact force of the SPM tip. It is suggested that SPM local oxidation can be upscaled by using a SPM tip with large contact length.     

Reaction between magnesium ammine complex compound and lithium hydride

The possibility of using ammonia as a hydrogen carrier is examined for the reaction between magnesium ammine complex MgCl₂(NH₃)₆ and lithium hydride LiH. Sample was milled at low temperature of −40 °C to avoid decomposition of MgCl₂(NH₃)₆ during the milling. The effects of milling time, milling speed (revolutions per minute), and catalysts on hydrogen storage properties were investigated by thermogravimetry, thermal desorption mass spectroscopy, and X-ray diffraction experiments. Experimental results indicated that a milled composite of Mg(NH₃)₆Cl₂ and catalyzed-LiH desorbed the ∼100% H₂ gas even at 125 °C in a closed system. The reverse reaction also proceeded by separately cooling MgCl₂ at lower temperature than 100 °C and heating LiNH₂ at 300 °C in the closed system.     

Phase and morphology evolution study of ball milled Mg–Co hydrogen storage alloys

Ball milled Mg–Co alloys with body-centered cubic structure (BCC) may absorb hydrogen at 258 K with a hydrogen capacity around 3 mass%. The phase and morphology evolution process of Mg₅₀Co₅₀ alloys ball milled for 0.5 h–400 h was studied by X-ray diffraction and scanning electron microscope. The formation mechanism of the Mg₅₀Co₅₀ alloys was clarified. Mg₅₀Co₅₀ alloys ball milled for various durations were found to present different hydrogen storage properties which could result from the phase and morphology difference in these samples.     

Microstructure and hydrogen desorption characteristics of hydrogenated ScH2–MBn (M = Mg and Ca) systems synthesized by mechanical milling

The mixtures of scandium hydride ScH₂ and metal boride MB_n, which is MgB₂ or CaB₆, were hydrogenated by mechanical milling under hydrogen pressure at room temperature. ScH₂–MgB₂ and ScH₂–CaB₆ desorbed 3.4 and 2.3 mass% of H₂, respectively, with peaks below 300 °C. The results of synchrotron radiation X-ray powder diffraction and X-ray absorption spectroscopy at the Sc K-edge indicated that ScB₂ was produced by milling. Fourier-transform infrared spectroscopy suggested that hydrogen was stored as B–H bonds in the as-milled samples. Nuclear magnetic resonance spectroscopy clarified the presence of metal borohydrides M(BH₄)₂ (M = Mg and Ca) in the as-milled ScH₂–MB_n mixtures. These results indicate that M(BH₄)₂ is synthesized by milling the ScH₂–MB_n mixtures under hydrogen pressure at room temperature, and hydrogen was desorbed from M(BH₄)₂. The by-products of M(BH₄)₂ are MgH₂ in the M = Mg case, which was observed by transmission electron microscopy, and ScB₂ in both cases.