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In this paper, we study complex symmetric C0-semigroups on the Bergman space A2(ℂ+) of the right half-plane ℂ+. In contrast to the classical case, we prove that the only involutive composition operator on A2(ℂ+) is the identity operator, and the class of J-symmetric composition operators does not coincide with the class of normal composition operators. In addition, we divide semigroups {ϕt} of linear fractional self-maps of ℂ+ into two classes. We show that the associated composition operator semigroup {Tt} is strongly continuous and identify its infinitesimal generator. As an application, we characterize Jσ-symmetric C0-semigroups of composition operators on A2(ℂ+).

Earthquake prediction is one of the most difficult problems in modern natural science. Undoubtedly, various seismic parameters included in broadband radiated energy catalogue of NEIC is very important data source of investigate correlation between different earthquake within specific time space scope. In the paper, a fitting mode of seismic energy based on Support Vector Machine is established, using which we can fill the absent energy filed in the broadband radiated energy catalogue.

Earthquake prediction is one of the most difficult problems in modern natural science. Undoubtedly, various seismic parameters included in broadband radiated energy catalogue of NEIC is very important data source of investigate correlation between differernt earthquake within specific time space scope and earthquake prediction. In the paper, we a linear fitting mode of seismic magnitude based on method of least squares and seismic energy is established, using which we can fill the absent energy filed in the broadband radiated energy catalogue.

Earthquake prediction is a difficult global scientific problem. As one aspect of the earthquake prediction, seismicity prediction and subsequent earthquake is also a big difficult of science problems. Analysis of the seismic sequence and the study of the main parameters (magnitude, radiation energy, apparent stress, seismic moment) and subsequent aftershocks is an important basis for prediction of seismicity and subsequent strong earthquakes. In this study, the relations between some of main shock parameters and the maximum aftershock are obtained based on association rules.

In order to extract characteristic values of graphene, a method based on a series of digital image processing algorithms was proposed in this paper. Using the method, we can automatically analyze topology structure and calculate amount of carbon atoms, and even calculate chiral vector indices (n, m) during in-situ TEM scanning of graphene. At last, we also write the correlative software with c++, which applying the digital image processing algorithms, and give out the processing result of several classic TEM image of graphene.

Iron-filled carbon nanotubes (CNTs) were synthesized using a floating catalyst chemical vapor deposition method with a great excess of ferrocene (more than 30 mg/min of vaporization rate) at 800 ∘ C. The amount of ferrocene is more than that in previous reports. The ferrocene was employed as both catalyst precursor and an iron source. Our observations indicate that the CNTs were more than 10 micrometer in length, with an outer diameter of 20–100 nm and inner diameter of 10–30 nm. The inner cavity of the CNTs was partial filled with iron nanowires. Magnetic property measurements reveal that the iron-filled CNTs exhibit an average coercivity of about 257.05 G.

Carbon nanofibers have been attracted many attentions for their potential applications in nanocomposites and electromagnetic wave-absorbing materials due to their remarkable mechanical, electrical and other properties. Ethanol as carbon source possesses low toxicity, easier storage and transportation. In this paper, we report ethanol catalytic chemical vapor deposition (ECCVD) for synthesizing carbon nanofibers. We utilized ferrocene as catalyst precursor and use ethanol as carbon source to synthesize carbon nanofibers by ethanol chemical vapor deposition. The deposits were characterized by employed scanning electron microscopy, transmission electron microscope and Raman spectroscopy.

It is very important to study the effects of various factors on synthesis of carbon nanofibers for controlled synthesis, which plays a significant role in realizing desired nanostructures or nanodevices for applications. In this report, we employed different carbon source and different catalyst precursor solution, respectively, and studied the effects of those on carbon nanofibers that were synthesized by catalytic combustion process. We have characterized the as-grown carbon nanofibers by employing scanning electron microscopy (SEM) for deep understanding.

The straight silica nano-rods with a diameter of about 200nm and smooth surface were synthesized by chemical vapor deposition method at 1300°C. The as-synthesized samples were characterized by means of scanning electron microscopy, energy dispersive x-ray, and transmission electron microscopy. The results show that as-synthesized silica nano-rods have a uniform size, well-defined shape, and smooth surface. However, the morphologies and microstructures of silica nano-rods are affected by synthesis conditions, such as the concentration of the SiOx and the the deposition temperature. On the basis of these experimental results, a possible growth mechanism of silica nano-rods in this process is proposed.

A simple combustion technique is presented for the preparation of mono-sized silica nanoparticles by employing tetraethyl orthosilicates as precursor. The as-grown white powders were characterized by means of scanning electron microscopy. The results showed the size of silica nanoparticles were relative to the unique synthesis conditions. According to the observation and analysis of the scanning electron microscopy images, the possible growth mechanism of silica nanoparticles in this process is proposed.

High-quality single-walled carbon nanotubes (SWNTs) are a key aspect in the emerging field nanotechnology. Although many approaches have been developed, the research on the synthesis of SWNTs is still needed. In this study, we report the synthesis of high-quality SWNTs by floating catalyst chemical vapor deposition, which employs ferrocene as the catalyst precursors. We obtained massive deposits at low temperature region. The deposits were characterized by scanning electron microscopy, transmission electron microscopy, and visual laser Raman spectroscopy. The Raman spectrum obtained from raw deposits shows clear radial breathing mode at the range from 180cm-1 to 300cm-1 and high-intensity graphite mode at 1577.7cm-1 with a shoulder at 1550.5cm-1, and almost no detectable peak around at 1545cm-1, which is induced by defects, is observed. These results indicate that the deposits are high-quality SWNTs.

The straight Y-shaped silica nanorods have been synthesized on Si wafer by thermal chemical evaporation of mixed powders of silica and graphite at 1300°C and condensation on Si substrate without assistance of any catalyst. The synthesized samples were characterized by means of scanning electron microscopy, transmission electron microscopy. The results suggested that the straight Y-shaped silica nanorods have uniform diameter about 50-200nm and neat smooth surface. The growth of such silica nanorods may be a result of the fluctuation of external conditions causing a change in the growth direction of silica nanorods developed.

A general, simple and economic synthetic method for synthesizing carbon nanofibers was presented. In the method, ethanol was employed as carbon source; metal salts such as nickel nitrate, ferric nitrate and ferric chloride were used as catalyst precursor respectively; copper plate was employed as the support material. A lot of products were obtained by catalytic combustion deposition of ethanol vapor. Then the as-prepared carbon nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, energy dispersion X-ray spectroscopy and selected-area electron diffractometry. By analyzing the results of characterization, the conclusions are as follows: 1) the large catalyst particles tend to form large-diameter CNFs, small catalyst particles are inclinable to form small-diameter CNFs; 2) the morphology of the catalyst can affect the final morphology of the CNFs. Moreover, the possible growth mechanisms were proposed and the degree of graphitization of samples was estimated by Raman spectroscopy characterization.

Catalytic grown carbon nanofibers have been obtained from decomposition of ethanol over copper plate. Ferric chloride of different concentration was employed as the catalyst precursor. Scanning electron microscopy has shown that different morphologies of carbon nanofibers can be obtained by using different concentration of catalyst precursor solution. The results from the Raman spectroscopic characterization have also demonstrated that the graphitization of carbon nanofibers can be tailored by control of the concentration of catalyst precursor solution. When the information from these characterization are combined with that of the associated morphologies of the carbon nanofibers, it is possible to synthesize perfect carbon nanofibers.

In this paper we report the preparation of carbon nanotubes (CNTs) by ethanol catalytic combustion (ECC) technique. We employed cobalt salt as catalyst precursors, copper plate as substrate and ethanol as carbon source. In order to have a better understanding of the growth mechanisms, we employed cobalt chloride, cobalt nitrite and cobalt sulfate as catalyst precursor to study the influence of catalysts on CNTs growth respectively. Entangled and nonseparated CNTs were aggregated together when the catalyst precursor was cobalt chloride, while straight and uniform CNTs were obtained when the catalyst precursor was cobalt sulfate. In the case of using cobalt nitrite as catalyst precursor, the CNTs tend to form helical and disordered structure. We have examined the morphology and microstructure of the obtained CNTs and discussed the growth mechanism.

Carbon nanofibers have been obtained by the interaction of ethanol with metal chloride over copper plate. Different metal chloride was used as the catalyst precursor. The products were characterized by the Raman spectroscopy for the degree of graphitization. The relative intensities and the amount of amorphous carbon were estimated. The results indicate that the catalyst precursor has effects on the degree of graphitization of carbon nanofibers.

Y-shaped carbon nanowires as a multi-branched carbon nanostructure have potential applications in electrical nano-devices. In this paper, we report the synthesis of Y-shaped carbon nanowires obtained from ethanol flames. These Y-shaped carbon nanowires have different morphologies from one to another. It is interesting that there are two Y-junctions on individual carbon nanowires. According to our experimental results, the growth mechanism of Y-shaped carbon nanowires has been discussed and a possible growth model of these Y-shaped carbon nanowires has been proposed.

A simple method was reported for synthesis of carbon nanofibers. Ethanol burner was employed as the setup. Different morphological carbon nanofibers were synthesized by the decomposition of ethanol. As-grown carbon nanofibers were characterized. The results indicate that depending on the size of catalyst, carbon deposits with different morphologies were produced.

In this paper, we study the compactness of the product of a composition operator with another one’s adjoint on the Bergman space. Some necessary and sufficient conditions for such operators to be compact are given.