Influence of phosphorous addition on Bi<Subscript>3</Subscript>Mo<Subscript>2</Subscript>Fe<Subscript>1</Subscript> oxide catalysts for the oxidative dehydrogenation of 1-butene

Bi₃Mo₂Fe₁P _x oxide catalysts were prepared by a co-precipitation method and the influence of phosphorous content on the catalytic performance in the oxidative dehydrogenation of 1-butene was investigated. The addition of phosphorous up to 0.4mole ratio to Bi₃Mo₂Fe₁ oxide catalyst led to an increase in the catalytic performance; however, a higher phosphorous content (above P=0.4) led to a decrease of conversion. Of the tested catalysts, Bi₃Mo₂Fe₁P_0.4 oxide catalyst exhibited the highest catalytic performance. Characterization results showed that the catalytic performance was related to the quantity of a π-allylic intermediate, facile desorption behavior of adsorbed intermediates and ability for re-oxidation of catalysts.     

Production of polyhydroxyalkanoates by batch and fed-batch cultivations of <Emphasis Type="Italic">Bacillus megaterium</Emphasis> from acid-treated red algae

Polyhydroxyalkanoates (PHAs) are linear polyesters synthesized by microbial fermentation of various substrates. PHAs are accumulated in microbial cells in order to store carbon and energy for future use. We used acid-pre-treated red alga (Gelidium amansii) as a cheap, abundant carbon source to produce PHA via batch and fed-batch cultivation of Bacillus megaterium KCTC 2194. After acid treatment of 10% (w/v) G. amansii, 25.5 g/L galactose, 3.6 g/L glucose, 6 g/L 5-HMF, and 1.05 g/L levulinic acid were formed. In batch culture at pH 7, the dry cell weight (DCW) and PHA content increased to 5.5 g/L and 51.4%, respectively. The cell concentration was enhanced by fed-batch cultivation using two feeding strategies: pH-stat and intermittent feeding. When the pH-stat feeding strategy was employed to add concentrated hydrolysate to the fermentor, DCW increased to 8.2 g/L, with 53.2% PHA content. When concentrated hydrolysate was fed using the intermittent feeding strategy, higher DCW (10.1 g/L) was obtained, along with a slight increase of PHA content to 54.5%. This study demonstrates that red algae could be used after simple acid treatment, to produce PHA without steps for enzymatic hydrolysis and inhibitor removal.     

Preparation and physical properties of an epoxy nanocomposite with amine‐functionalized graphenes

Graphene, consisted of a single layer of carbon atom in a two‐dimensional lattice, has superior electrical and physical properties that promise many exciting applications. In this study, graphenes were prepared from graphite powder by chemical method and their images were investigated by TEM and SEM. To develop high performance epoxy nanocomposites with good dispersion of graphenes and strong epoxy‐graphene interfacial bonding, graphenes were amine‐functionalized and the effects of the amine‐functionalization on the curing behavior and physical properties of epoxy/graphene nanocomposites were studied. FTIR spectra confirmed the amine‐functionalization. The physical properties of the nanocomposites were investigated by DSC, DMA, TMA, and impact tester. Fracture surfaces were investigated by SEM. The physical properties of the nanocomposites could be improved considerably by the amine‐functionalization of graphenes. POLYM. ENG. SCI., 54:985–991, 2014. © 2012 Society of Plastics Engineers     

Enhancement in High-Field J c Properties and the Flux Pinning Mechanism of MgB2 Thin Films on Crystalline SiC Buffer Layers

We have studied the influence of crystalline SiC buffer layers on the critical current density and on the flux pinning mechanism in MgB₂ thin films. Crystalline SiC buffer layers were deposited on the Al₂O₃ (0001) substrates by using a pulsed laser deposition method, and then MgB₂ thin films were grown on the SiC-buffered layer by using a hybrid physical-chemical vapor deposition technique. MgB₂ thin films with crystalline SiC-buffered layers showed a significant critical current density’s enhancement in the high magnetic field region. An uncommon plateau-like behavior was also observed when the normalized flux pinning force density was scaled with the reduced magnetic field. Based on the analyses of the scaling behavior of the flux pinning force, grain boundary pinning is likely to be a dominant pinning mechanism in the SiC-buffered MgB₂ thin films.     

A Gauss–Seidel type solver for the fast computation of input-constrained control systems

An important class of nonlinear control systems can be represented as the feedback interconnection of two parts: a linear time-invariant system and a block of decentralized nonlinearities. When the linear time-invariant part has a nontrivial feedthrough term or the nonlinearity has a feedback gain, control computation involves the online implementation of a multivariable algebraic loop which must be resolved at each sampling instant. The requirements for such online computation may result in several implementation issues, especially in real-time and embedded control applications. This paper considers the implementation of such algebraic loops arising from several input-constrained systems. The proposed solution algorithm is globally convergent for a very large class of feedthrough or feedback gains and shows promise for real-time and embedded control applications where a fast but approximate solution is of the essence.     

Electron-Spin-Resonance Study of Polycrystalline Zn1−x Cr x O Ceramics

The structural and magnetic properties of polycrystalline ceramics of Zn_1?x Cr _x O (x=0.01–0.10) annealed at 900 and 1200 °C were systematically investigated by means of X-ray diffractometer, electron spin resonance (ESR) spectroscopy, and a superconducting quantum interference device magnetometer. A coexistence of two structural phases of wurtzite-ZnO and spinel-ZnCr₂O₄ was found even in the samples with the lowest Cr-doping concentration of 1 at.%. Our experimental results have indicated that Cr ions are incorporated into the Zn site of the ZnO host lattice, and act as paramagnetic centers. Higher annealing temperature enhances the formation tendency of ZnCr₂O₄, and the proportion of Cr²⁺ relative to Cr³⁺ in ZnO. This results in the broadening of ESR spectral line. Dipole exchange interactions due to Cr³⁺–Cr³⁺, Cr³⁺–Cr²⁺, and Cr²⁺–Cr²⁺ pairs are assigned to be responsible for the ESR signals and paramagnetic behavior of Zn_1?x Cr _x O samples.     

A performance evaluation of information security training in public sector

Recently, as the incidents of the security breach and the personal information leakage in public institutions and the major information/communication infrastructure have increased, the importance of the development and training of human resources specialized in cybersecurity, who can immediately respond to this are emphasized. Accordingly, the government has announced policies for the development of human resources, established and operated public sector cybersecurity training centers; however, there is no method for understanding the investment performance and effect of the present cybersecurity education/training in the public sector. For the establishment of a training system and the quality control of continuing education, a method for evaluating the performance of the training is needed, and this can prove the justification of the promotion of the training program and the sustainability of the training center. The goal of this study is to analyze the outcome of education and training in the field of information security and economic return on investment. For this purpose, through literature research on the outcome of the domestic and overseas education and training, this study drew a model that can apply.     

Effect of Nanoencapsulated Vitamin B1 Derivative on Inhibition of Both Mycelial Growth and Spore Germination of Fusarium oxysporum f. sp. raphani

Nanoencapsulation of thiamine dilauryl sulfate (TDS), a vitamin B1 derivative, was proved to effectively inhibit the spore germination of Fusarium oxysporum f. sp. raphani (F. oxysporum), as well as mycelial growth. The average diameter of nanoparticles was measured as 136 nm by being encapsulated with an edible encapsulant, lecithin, whose encapsulation efficiency was about 55% in containing 200 ppm of TDS concentration: the 100 ppm TDS nanoparticle solution showed a mycelial growth inhibition rate of 59%. These results were about similar or even better than the cases of treating 100 ppm of dazomet, a positive antifungal control (64%). Moreover, kinetic analysis of inhibiting spore germination were estimated as 6.6% reduction of spore germination rates after 24 h treatment, which were 3.3% similar to the case of treating 100 ppm of a positive control (dazomet) for the same treatment time. It was also found that TDS itself could work as an antifungal agent by inhibiting both mycelial growth and spore germination, even though its efficacy was lower than those of nanoparticles. Nanoparticles especially played a more efficient role in limiting the spore germination, due to their easy penetration into hard cell membranes and long resident time on the surface of the spore shell walls. In this work, it was first demonstrated that the nanoparticle of TDS not a harmful chemical can control the growth of F. oxysporum by using a lower dosage than commercial herbicides, as well as the inhibiting mechanism of the TDS. However, field trials of the TDS nanoparticles encapsulated with lecithin should be further studied to be effectively used for field applications.     

Effect of negative pressure on superconducting transition temperature of MgB2

Atomistic simulation has been performed with interatomic potentials to investigate the effect of negative hydrostatic pressure on the superconducting transition temperature (T_c) of MgB₂. The calculation reveals that T_c can be greatly enhanced by applying negative pressure and it can reach up to 52.2 K at ?13 GPa, about 13 K higher than that at ambient pressure. The mechanism for the enhancement of T_c is attributed to that negative pressure reduces high-frequency phonon vibrations of B and thus dramatically enhances the electron–phonon coupling. Our result seems to open up a possible way for the enhancement of T_c in MgB₂.