Enhanced Photocatalytic Efficiency of Nanoscale NiS2/TiO2 Catalysts Synthesized by Hydrothermal and Sol-gel Method

Lei Zhu,Ze-Da Meng,Trisha Ghosh,오원춘 한국세라믹학회 2012 한국세라믹학회지 Vol.49 No.2

To improve the visible-light induced photocatalytic application performances of TiO2, in this study, the NiS2 modied TiO2 composites were prepared by two methods: hydrothermal method and sol–gel method. The composites were denoted as hs-NiS2/TiO2, and sg-NiS2/TiO2 and characterized by XRD, UV-vis absorbance spectra, SEM, TEM, EDX, and BET analysis. The photocatalytic activities under visible light were investigated by the degradation of methyl orange (MO). The photodegradation rate of methyl orange under visible light with NiS2/TiO2 composites was markedly higher than that of pure TiO2, and the effect of hs-NiS2/TiO2 composites was better than that of sg-NiS2/TiO2. The results indicate that the hydrothermal process could partly inhibit the agglomeration of NiS2/TiO2. Thus, the dispersion of nanoparticles was improved, and that the promoting effect of NiS2 could extend the light absorption spectrum toward the visible region.

FDG PET-CT in Non-small Cell Lung Cancer: Relationship between Primary Tumor FDG Uptake and Extensional or Metastatic Potential

Zhu, Shou-Hui,Zhang, Yong,Yu, Yong-Hua,Fu, Zheng,Kong, Lei,Han, Da-Li,Fu, Lei,Yu, Jin-Ming,Li, Jia Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.5

Objective: To explore the relationships between primary tumor $^{18}F$-FDG uptake measured as the SUVmax and local extension, and nodal or distant organ metastasis in patients with NSCLC on pretreatment PET-CT. Methods: 93 patients with NSCLC who underwent $^{18}F$-FDG PET-CT scans before the treatment were included in the study. Primary tumor SUVmax was calculated; clinical stages, presence of local extension, nodal and distant organ metastases were recorded. The patients with SUVmax${\geq}2.5$ were divided into low and high SUVmax groups by using the median SUVmax. The low SUVmax group consisted of 45 patients with SUVmax<10.5, the high SUVmax group consisted of 46 patients with SUVmax${\geq}10.5$. Their data were compared statistically. Results: 91 cases with SUVmax${\geq}2.5$ were included for analysis. The mean SUVmax in patients without any metastasis was $7.42{\pm}2.91$ and this was significantly lower than that ($12.18{\pm}4.94$) in patients with nodal and/or distant organ metastasis (P=0.000). In the low SUV group, 19 patients had local extension, 22 had nodal metastasis, and 9 had distant organ metastasis. In the high SUV group, 31 patients had local extension, 37 had nodal metastasis, and 18 had distant organ metastases. There was a significant difference in local extension (P =0.016), distant organ metastasis (P =0.046), and most significant difference in nodal metastasis rate (P =0.002) between the two groups. In addition, there was a moderate correlation between SUVmax and tumor size (r = 0.642, P<0.001), tumor stage (r = 0.546, P<0.001), node stage (r = 0.388, P<0.001), and overall stage (r = 0.445, P= 0.000). Conclusion: Higher primary tumor SUVmax predicts higher extensional or metastatic potential in patients with NSCLC. Patients with higher SUVmax may need a close follow-up and more reasonable individual treatment because of their higher extensional and metastatic potential.

Analysis on the Operation of a Charging Station with Battery Energy Storage System

Zhu, Lei,Pu, Yongjian The Korean Institute of Electrical Engineers 2017 Journal of Electrical Engineering & Technology Vol.12 No.5

Fossil oil, as the main energy of transportation, is destined to be exhausted. The electrification of transportation is a sustainable solution to the energy crisis, since electric power could be acquired from the inexhaustible sun, wind and water. Among all the problems that hinder the development of Electric Vehicle (EV) industry, charging issue might be the most prominent one. In this paper, the service process of a charging station with Battery Energy Storage System (BESS) is analyzed by means of $Cram{\acute{e}}r$ - Lundberg model which has been intensively utilized in ruin theory. The service quality is proposed in two dimensions: the service efficiency and the service reliability. The arrival rate and State of Charge (SOC) upon arrival are derived from 2009 National Household Travel Survey (NHTS). The simulations are performed to show how the service quality is determined by the system parameters such as the number of servers, the service rate, the initial capacity, the charge rate and the maximum waiting time. At last, the economic analysis of the system is conducted and the best combination of the system parameters are given.

Low-temperature Synthesis of Graphene-CdLa2S4 Nanocomposite as Efficient Visible-light-active Photocatalysts

Lei Zhu,오원춘 한국세라믹학회 2015 한국세라믹학회지 Vol.52 No.3

We report the facile synthesis of graphene-CdLa2S4 composite through a facile solvothermal method at low temperature. The as-prepared products were characterized by X-ray diffraction (XRD) and by Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis and BET analysis, revealing the uniform covering of the graphene nanosheet with CdLa2S4 nanocrystals. The as-prepared samples show a higher efficiency for the photocatalytic degradation of typical MB dye compared with P25 and CdLa2S4 bulk nanoparticles. The enhancement of visible-light-responsive photocatalytic properties by decolorization of Rh.B dye may be attributed to the following causes. Firstly, graphene nanosheet is capable of accepting, transporting and storing electrons, and thus retarding or hindering the recombination of the electrons with the holes remaining on the excited CdLa2S4 nanoparticles. Secondly, graphene nanosheet can increase the adsorption of pollutants. The final cause is that their extended light absorption range. This work not only offers a simple way to synthesize graphene-based composites via a one-step process at low temperature but also a path to obtain efficient functional materials for environmental purification and other applications.

Effects of Exogenous Abscisic Acid on Phenolic Characteristics of Red Vitis vinifera Grapes and Wines

Lei Zhu,Yali Zhang,Wen Zhang,Jiang Lu 한국식품과학회 2016 Food Science and Biotechnology Vol.25 No.2

The effects of exogenous abscisic acid (ABA) on phenolic characteristics of grapes and wines were investigated in Vitis vinifera cvs. Merlot and Cabernet Sauvignon. Exogenous ABA treatment at veraison significantly improved phenolic contents, mainly anthocyanins and flavonols, and antioxidant properties of the grape skins, but had no effects on total phenolics and antioxidant activities in the seeds or on basic fruit qualities. The wines made from ABA-treated grapes were also consequently enhanced in total phenolics, anthocyanins, flavonols and antioxidant activities. The proportions of methylated anthocyanins in the skins and acylated anthocyanins and derived pigments in the wines were decreased to some degree by exogenous ABA treatment. No distinct relationships were observed between ABA concentrations and phenolic characteristics, and the effects were observed even with 200 mg/L ABA. The results revealed that exogenous ABA applied at veraison offered opportunities to improve phenolic contents and nutritional values of grape skins and wines.

Characterization of a Novel MnS-ACF/TiO₂ Composite and Photocatalytic Mechanism Derived from Organic Dye Decomposition

Zhu, Lei,Jo, Sun-Bok,Jo, Jung-Hwan,Ye, Shu,Ullah, Kefayat,Oh, Won-Chun The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.3

Activated carbon fiber (ACF) was modified with MnS nanoparticles to prepare MnS-ACF, and it was employed for preparation of MnS-$ACF/TiO_2$ composites with titanium (IV) n-butoxide (TNB). The properties of MnS-$ACF/TiO_2$ composites were characterized by XRD, SEM, and EDX. EDX results showed the presence of C, O, and Ti as major elements and traces of the metal elements Mn and S. The photocatlytic activity was evaluated by degradation of methyl blue (MB) and methyl orange (MO) dye. The results demonstrated that as-prepared samples could effectively photodegrade MB and MO under UV irradiation. Subsequently, the decomposition of MB solution showed the combined effects of adsorptions by ACF and enhanced photocatalytic effect by $TiO_2$. Finally, the photocatalytic effect increased due to photo-induced-electron absorption effect by ACF and electron trap effect by comodified MnS nanoparticles.

Analysis of Spatio-Temporal Patterns of Nighttime Light Brightness of Seoul Metropolitan Area using VIIRS-DNB Data

ZHU LEI,조대헌,이소영 한국국토정보공사 2017 지적과 국토정보 Vol.47 No.2

Visible Infrared Imaging Radiometer Suite Day-Night Band (VIIRS-DNB) data provides a much higher capability for observing and quantifying nighttime light (NTL) brightness in comparison with Defense Meteorological Satellite-Operational Linescan System (DMSP-OLS) data. In South Korea, there is little research on the detection of NTL brightness change using VIIRS-DNB data. This study analyzed the spatial distribution and change of NTL brightness between 2013 and 2016 using VIIRS-DNB data, and detected its spatial relation with possible influencing factors using regression models. The intra-year seasonality of NTL brightness in 2016 was also studied by analyzing the deviation and change clusters, as well as the influencing factors. Results are as follows: 1) The higher value of NTL brightness in 2013 and 2016 is concentrated in Seoul and its surrounding cities, which positively correlated with population density and residential areas, economic land use, and other factors; 2) There is a decreasing trend of NTL brightness from 2013 to 2016, which is obvious in Seoul, with the change of population density and area of industrial buildings as the main influencing factors; 3) Areas in Seoul, and some surrounding areas have high deviation of the intra-year NTL brightness, and 71% of the total areas have their highest NTL brightness in January, February, October, November and December; and 4) Change of NTL brightness between summer and winter demonstrated a significantly positive relation with snow cover area change, and a slightly and significantly negative relation with albedo change.

Sonophotocatalytic Performance of Bi₂Se₃-Graphene/TiO₂ Hybrid Nanomaterials Synthesized with a Microwave-assisted Method

Zhu, Lei,Jo, Sun-Bok,Ye, Shu,Ullah, Kefayat,Oh, Won-Chun The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.3

This paper introduces a microwave-assisted synthesis method to prepare hybrid $Bi_2Se_3-GR/TiO_2$ nanocomposites, which exhibit superior properties over single component materials. The as-prepared composites were characterized by XRD, UV-vis absorbance spectra, SEM,TEM, EDX, and BET analyses, revealing uniform covering of the graphene nanosheet with $Bi_2Se_3$ and $TiO_2$ nanocrystals. For visible light photocatalysis of Rh.B, a significant enhancement in the reaction rate was consequently observed with $Bi_2Se_3-GR/TiO_2$ composites. The degradation rate($k_{app}$) obtained for sonophotocatalysis was $6.8{\times}10^{-3}min^{-1}$, roughly 2.2 times better than that of VL photocatalysis under higher concentrations of Rh.B. The sonophotocatalysis was faster due to greater formation of reactive radicals as well as an increase of the active surface area of the $Bi_2Se_3-GR/TiO_2$ composites. The high activity is attributed to the synergetic effects of high charge mobility and red shift of the absorption edge of $Bi_2Se_3-GR/TiO_2$.

Sonochemical Synthesis and Sonocatalysis Performance Behavior of Ag2Se and Ag2Se/TiO2 Nanocomposites

Lei Zhu,오원춘 한국세라믹학회 2015 한국세라믹학회지 Vol.52 No.6

In this study, novel Ag2Se sensitized TiO2 nanocomposites were prepared by facile sonochemical assisted synthesis method. The as-prepared products were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), and N2 adsorption BET analysis. The as-prepared Ag2Se/TiO2 nanocomposites simultaneously possessed great adsorptivity for organic dyes and efficient charge separation properties. In the decolorization of rhodamine B, a significant enhancement in the reaction rate was observed for the Ag2Se/TiO2 nanocomposite compared to the cases of using pure P25 or TiO2. The sonocatalysis activity was higher due to the greater formation of reactive radicals, as well as to the increase of the active surface area of the Ag2Se/TiO2 nanocomposite.

Additional Effect of Zeolite Based on Bactericidal Activated Carbon Spheres with Enhanced Adsorption Effect and Higher Ignition Temperature

Zhu, Lei,Ye, Shu,Asghar, Ali,Bang, Seong-Ho,Oh, Won-Chun The Korean Ceramic Society 2016 한국세라믹학회지 Vol.53 No.1

In this study, the fabrication of zeolite combined activated carbon spherical samples was carried out as follows. Briefly, ZSM-5 zeolite and activated carbon were composed as main absorbent materials; by controlling the weight percentage of zeolite and binder materials, a series of spherical samples (AZP 4, 6, 8) were prepared. These spherical samples were characterized by BET, XRD, SEM, EDX, and pressure drop; benzene and iodine adsorption tests, bactericidal effect test, and ignition temperature test were also performed. The adsorption capability was found to depend on the BET surface area; the spherical samples AZP6 with high BET surface area of $1011m^2/g$ not only exhibited excellent removal effects for benzene (24.9%) and iodine (920mg/g) but also a good bactericidal effect. The enhanced ignition temperature may be attributed to the homogeneous dispersion conditions and the proper weight percentage ratio between zeolite and activated carbon.