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Doped nitrogen significantly increased the nitrobenzene conversion and selectivity for aniline. Graphitic nitrogen is conducive to the adsorption of nitrobenzene and basic pyridinic nitrogen has a positive effect on the activation of formic acid.

CeO2-promoted Co–N–C hybrids were prepared by the strategy of solid solution construction for the deoxygenation of sulfoxide.

The ripples of dc input voltage belong to cascaded systems are usually close to the sinusoidal voltage, and its stability is quite different from that of dc constant voltage converters. Under the premise of no loss of generality, this article takes the output voltage of front-end converter in a cascaded system as sine wave, discusses the principle of closed-loop switching converters driven by sinusoidal input voltage, and calculates the average value of fixed-point state variables by using a discrete-time mathematical model. In addition, Filippov method is adopted to predict bifurcation by calculating the eigenvalues of Monodromy matrix belonging to the whole system, and the mechanism of nonlinear phenomena is also addressed. The results show that bifurcation points change obviously under different input conditions. Moreover, the influence of sinusoidal ripples amplitude and phase shift on bifurcation behavior is discussed, the compensation technique is used to prevent bifurcation and obtain the extended stability region of the circuit parameters. The experimental results prove the validity of the analysis.

Ceria-promoted Co@NC (NC, N doped carbon) catalysts are prepared by pyrolysis of biomass materials. Characterization results indicate that ceria and Co species facilitate the distribution of each other due to the formation of a Ce–O–Co solid solution. The specific surface area of the catalyst increased from 378.77 to 537.7 m2 g−1via the introduction of ceria. The electron transfer from Co to Ce further enhanced their interaction, and Co species facilitate the formation of more defective oxygen vacancies on ceria, which are beneficial to the activities of catalytic hydrogenation and catalytic transfer hydrogenation (CTH), respectively. Thus, Co/Ce@NC (0.99% Co loading) pyrolyzed at 850 °C exhibits excellent performance in the hydrodeoxygenation (HDO) of vanillin with high metal utilization. Catalytic hydrogenation and CTH coexisted in the presence of H2 and ethanol, and >99% yield of creosol can be obtained in each of them. The reaction processes are monitored. No intermediate is found in aqueous media, while ethoxymethyl-4-methoxy-2-phenol is detected in ethanol. Moreover, Co/Ce@NC presents outstanding stability and general applicability. This work provides new insights into the construction of M@NC (M, metal) catalysts and the HDO process of biofuel upgrade.

Three fluorinated phenothiazine compounds (P-1, P-2, P-3) were synthesized and characterized. It was found that all of them displayed significant solvatochromism and aggregation-induced emission behaviors. It was worth noting that P-1 and P-2 exhibited obvious mechanochromic properties compared to P-3. Specifically, P-1 displayed two different colors upon grinding and smashing, and emission bands showed different shift direction. P-2 exhibited polymorphic emission, its powder emitted yellow fluorescence, whereas crystal emitted orange fluorescence. After grinding, these two states had red shifts of 76 nm and 35 nm, respectively. But P-3 only presented a red shift of 10 nm. In addition, P-1 and P-2 also had thermochromic properties. After heating, their maximum emission wavelengths all would red-shift, and the maximum red shift can be up to 71 nm. These results can be explained by wide-angle X-ray diffraction, the differential scanning calorimetry and single crystal diffraction analysis. This work provided a new idea for the preparation of materials with both mechanochromic and thermochromic characteristics.

Mismatch between switching frequency and circuit parameters often occurs in industrial applications, which would lead to instability phenomena. The bifurcation behavior of V² controlled buck converter is investigated as the pulse width modulation period is varied. Nonlinear behavior is analyzed based on the monodromy matrix of the system. We observed that the stable period-1 orbit was first transformed to the period-2 bifurcation, which subsequently changed to chaos. The mechanism of the series of period-2 bifurcations shows that the characteristic eigenvalue of the monodromy matrix passes through the unit circle along the negative real axis. Resonant parametric perturbation technique has been applied to prevent the onset of instability. Meanwhile, the extended stability region of the converter is obtained. Simulation and experimental prototypes are built, and the corresponding results verify the theoretical analysis.

For the purpose of designing an intrinsic safety Flyback converter with minimal output voltage ripple based on a specified output current, this paper first classified the energy transmission modes of the system into three sorts, namely, the Complete Inductor Supply Mode-CCM (CISM-CCM), the Incomplete Inductor Supply Mode-CCM (IISM-CCM) and the Incomplete Inductor Supply Mode-DCM (IISM-DCM). Then, the critical secondary self-inductance assorting the three modes are deduced and expressions of the output voltage ripples (OVR) are presented. For a Flyback converter with constant loads and switching frequency, it is shown that the output voltage ripple in the CISM-CCM is the smallest and that it has no relationship with the secondary self-inductance. Otherwise, the OVR of the other two modes are bigger than the previously mentioned one. It is concluded that the critical inductance between the CISM-CCM and the IISM-CCM is the minimal secondary self-inductance to ensure the smallest output voltage ripple. At last, a design method to guarantee the minimum OVR within the scales of the input voltage and load are analyzed, and the minimum secondary self-inductance is proposed to minimize the OVR. Simulations and experiments are given to verify the results.

Three diverse layers of eggshell membrane (ESM) were introduced in a biogenic sol-gel technique for the synthesis of hierarchical SnO(2) nanomaterials with corresponding configurations. Typically, the biomorphic replication of the interwoven inner eggshell membrane was systematically investigated by controlling synthesis conditions such as pH value, dipping time, and calcination temperature. The as-prepared SnO(2) tubes consisting of interconnected 5-nm nanocrystallite units were successfully interwoven into ESM-morphic films. Herein, the biomaterial ESM served both as the physical substrate and the functional macromolecule template to realize the precision replication, by the interactions between ESM macromolecules (containing carboxyl, hydroxy, amino groups, etc.) and Sri colloid ingredients, Moreover, some biomacro-molecules also acted as the surfactant to yield small-scaled and well-distributed SnO(2) nanocrystallites based on the strong bondage of short-chained amino acids within ESM glycoprotein with SnO(2) nuclei. This technique can be attributed to a biomimetic sol-gel process and is widely applicable to the synthesis of other functional material systems. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007).

A facile and versatile method is reported to fabricate the interwoven tubular hierarchy of SnO2 films using a biotemplate eggshell membrane (ESM) combined sol–gel approach. In order to promote the crystallization of SnO2 films, calcination is necessary and can adjust the size of the building units in the range 2.8–26 nm. Under the direction of ESM biomacromolecules, SnO2 nanocrystallites come into being and assemble into nanotubes, and further pattern porous hierarchical meshworks to faithfully retain the morphology of natural ESM. The sensor performance of as-prepared biomorphic SnO2 was measured for ethanol, liquefied petroleum gas (LPG), H2S, and gasoline. It is found that the SnO2 hierarchical films obtained have a good selectivity for LPG with a working temperature above 300 °C while for ethanol below 270 °C.

The bonding and electronic structures of oxygen molecules adsorbed on Al (001) are theoretically investigated from first-principles using the density functional theory within the generalization gradient approximation (GGA) and a supercell approach. The surface is described by means of a 2 × 2 cell with a thickness of fourteen layers, which consist of 9 layers of Al atoms and 5 layers of vacuum. Oxygen molecules are situated on Al surface. The calculated results indicate that oxygen molecules with their axes parallel to the Al surface are the energetically easiest to be adsorbed on Al (001), while those vertical to the Al surface are the most difficult. There are two different processes for the adsorption of oxygen molecules on Al (001), which are O2→(O2)2−→2O−→2O2− and O2→(O2)−→O2−+O, and their occurrences are strongly dependent on the initial morphologies.