Controlled Synthesis of Nano- and Micro-sized Carbon Materials and Their Uses

Nagasaki Symposium on Nano-Dynamics 2008 (NSND2008) 平成20年1月29日(火)於長崎大学 Invited Lectur

Highly Dispersed Rh/NbOx Invoking High Catalytic Performances for the Valorization of Lignin Monophenols and Lignin Oil into Aromatics

As fossil fuels are constantly depleted, valorization of lignocellulosic biomass into valuable aromatic compounds is of great significance but exceedingly challenging. In this work, the structure and catalytic performance of various Rh/Nb2O5 catalysts were studied in detail via the catalytic hydrodeoxygenation of a representative lignin monophenol compound 2-methoxy-4-propylphenol. The best catalytic performance was obtained over Rh/Nb2O5-400 (Nb2O5 calcined at 400 °C) with an exceptional 98% yield of propylbenzene under 0.5 MPa H2, which was mainly due to the cooperation between highly dispersed Rh metals and NbOx species, in which Rh was responsible for dissociation of H2 and NbOx for breaking of C−O bonds at the metal−support interface. Besides, the lignin oil obtained in depolymerization of raw pine wood was directly used as the substrate in the catalytic hydrodeoxygenation reaction over the Rh/Nb2O5-400 catalyst under 0.5 MPa H2. Encouragingly, the liquid products were identified and found that lignin oil was completely converted into C6−C10 hydrocarbons (\u3e99% selectivity) with an 80.1 mol % yield of aromatics. The results achieved in this work highlighted that high-value utilization of lignocellulosic biomass feedstocks to produce aromatic chemicals and liquid fuels could be achieved over Rh/Nb2O5 under a low hydrogen pressure

Promotion of Au nanoparticles on carbon frameworks for alkali-free aerobic oxidation of benzyl alcohol

We synthesized a series of modified Co-ZIF-67 materials with tunable morphology to support fine Au nanoparticles for the alkali-free aerobic oxidation of benzyl alcohol. Structure promotion was performed using Stöber silica as a hard template, which was subsequently removed by NaOH etching before gold immobilization. The texture structure of Au/(Si)C was greatly improved with increasing surface area and volume. CoOx was simultaneously introduced into the carbon shell from the Co-ZIF-67 precursor, which consequently facilitated the specific Au-support interaction via bimetallic synergy. XRD, XPS, and TEM images demonstrated the redispersion of both Au and CoOx as well as the electronic delivery between metals. Analysis of the chemical and surface composition suggested a surface rich in Auδ+ with abundant lattice oxygen contributed by CoOx in the final Au/(Si)C, which improved the transformation rate of benzyl alcohol even in an alkali-free condition. Au/(Si)C with finely dispersed Au particles showed excellent catalytic performance in the alkali-free environment, with 89.3% benzyl conversion and 74.5% benzaldehyde yield under very mild conditions

MSGraph: Modeling multi-scale K-line sequences with graph attention network for profitable indices recommendation

Indices recommendation is a long-standing topic in stock market investment. Predicting the future trends of indices and ranking them based on the prediction results is the main scheme for indices recommendation. How to improve the forecasting performance is the central issue of this study. Inspired by the widely used trend-following investing strategy in financial investment, the indices' future trends are related to not only the nearby transaction data but also the long-term historical data. This article proposes the MSGraph, which tries to improve the index ranking performance by modeling the correlations of short and long-term historical embeddings with the graph attention network. The original minute-level transaction data is first synthesized into a series of K-line sequences with varying time scales. Each K-line sequence is input into a long short-term memory network (LSTM) to get the sequence embedding. Then, the embeddings for all indices with the same scale are fed into a graph convolutional network to achieve index aggregation. All the aggregated embeddings for the same index are input into a graph attention network to fuse the scale interactions. Finally, a fully connected network produces the index return ratio for the next day, and the recommended indices are obtained through ranking. In total, 60 indices in the Chinese stock market are selected as experimental data. The mean reciprocal rank, precision, accuracy and investment return ratio are used as evaluation metrics. The comparison results show that our method achieves state-of-the-art results in all evaluation metrics, and the ablation study also demonstrates that the combination of multiple scale K-lines facilitates the indices recommendation

Carbon nanotube supported platinum-palladium nanoparticles for formic acid oxidation

Pt, Pd and PtxPdy alloy nanoparticles (Pt1Pd1, Pt1Pd3, atomic ratio of Pt to Pd is 1:1, 1:3, respectively) supported on carbon nanotube (CNT) with high and uniform dispersion were prepared by a modified ethylene glycol method. Transmission electron microscopy images show that small Pt and PtxPdy nanoparticles are homogeneously dispersed on the outer walls of CNT, while Pd nanoparticles have some aggregations and comparatively larger particle size. The average particle sizes of Pt/CNT, Pt1Pd1/CNT, Pt1Pd3/CNT and Pd/CNT obtained from the Pt/Pd (2 2 0) diffraction peaks in the X-ray diffraction patterns are 2.0, 2.4, 3.1 and 5.4 nm, respectively. With increasing Pd amount of the catalysts, the mass activity of formic acid oxidation reaction (FAOR) on the CNT supported catalysts increases in both cyclic voltammetry (CV) and chronoamperometry (CA) tests, although the particle size gets larger (thus, the relative surface area gets smaller). The CV study indicates a \u27direct oxidation pathway\u27 of FAOR occurred on the Pd surface, while on the Pt surface, the FAOR goes through \u27COads intermediate pathway\u27. Pd/CNT demonstrates 7 times better FAOR mass activity than Pt/CNT (2.3 mA/mgPd vs. 0.33 mA/mgPt) at an applied potential of 0.27 V (vs. RHE) in the CA test. © 2010 Elsevier Ltd. All rights reserved

Influence Factors Analysis of Provincial Divorce Rate Spatial Distribution in China

Divorce is the primary factor affecting the harmony and stability of the family and society. This paper uses spatial statistics to analyze the potential social causes of influencing the spatial distribution of divorce rates in various provinces of China. Firstly, the factors of social influence, family cohesion, and ethnic customs are constructed by factor analysis, then the spatial interaction effect of divorce rate in each province is brought into the model, and the spatial regression analysis of these three factors is carried out. The results show that social influence, especially the tertiary industry share of GDP, has a significant influence on the divorce rate, family cohesion has a distinct negative effect on the divorce rate, and ethnic customs have a noteworthy impact on the divorce rate. It is reflected in the high divorce rate of the majority of ethnic minority population, while, in the spatial data processing, the factor spatial lag model (FSLM) is better than the ordinary least square (OLS) regression model

Full Digital Processing System of Photoelectric Encoder

A photoelectric signal, output by a photoelectric receiver, may detrimentally change after the photoelectric encoder is used for a period of time or when the environment changes; this will directly affect the accuracy of the encoder and lead to fatal errors in the encoder. To maintain its high accuracy, we propose an encoder that can work in a variety of environments and that adopts full digital processing. A signal current that travels from the receiver of a photoelectric encoder is converted into a voltage signal via current limiting resistance. All signals are directly processed in the data processor component of the system. The encoder converts all the signals into its normalized counterpart. Then, the angle of the encoder is calculated using the normalized value. The calculated encoder angle compensates for any error. The final encoder angle is obtained, and the encoder angle is output accordingly. Experiments show that this method can greatly reduce the encoder’s volume. This method also reduces the encoder error from 167 arcseconds to 53 arcseconds. The encoder can still maintain a high accuracy during environmental changes, especially in harsh environments where there are higher accuracy requirements