Antibacterial Characteristics of ZnO-CeO_2 Nano-Powder Prepared byLaser Vapor Condensation

Antibacterial activity of ZnO-CeO2 solid nano-powders was studied by measuring the change of sterilization efficacy to the bacterial. ZnO-CeO2 nano-powders were prepared by laser vapor condensation (LVC) with oxygen as loading gas. The size of the particle can be affected greatly by some reacting conditions such as the flow of loading gas and the reacting pressure. Rod-like powders with different molar ratios (Zn/Ce) and sizes were produced in the changed reacting conditions for studying the effects of sterilization efficacy to the bacterial. It is found that antibacterial activity of oxide powders increase with decreasing particle size and increasing ceria concentration. The changes of antibacterial action for S. aureus are similar to those for B.niger. Both the preparing mechanism of LVC and the sterilization assumption were proposed.

Enhanced Oxidation Resistance of Iron Nanoparticles via Surface Modification in Chemical Vapor Condensation Process

In order to prevent the oxide formation on the surface of nano-size iron particles and thereby to improve the oxidation resistance in ordinary condition, iron nanoparticles synthesized by a chemical vapor condensation method were directly soaked in hexadecanethiol solution to coat them with a polymer layer. Oxygen content in the polymer-coated iron nanoparticles was significantly lower than that in usual air-passivated particles possessing iron-core/oxide-shell structure. Accordingly, oxidation resistance of the polymer-coated particles at an elevated temperature below 130℃ in air was 10-40 times higher than that of the normally passivated particles.

Analysis on Concentration and Source Rate of Precursor Vapors Participating in Particle Formation and Growth at Xinken in the Pearl River Delta of China

Concentration and source rate of precursor vapors participating in particle formation and subsequent growth were investigated during the Pearl River Delta intensive campaign （PRD2004, October 2004） in southeastern China. Four new particle formation event days and a typical non-event day were selected for our analysis. Atmospheric sulphuric acid, the important precursor vapor in nucleation and growth, were simulated with a pseudo steady-state model based on the measurements of SO2, NOx, 03, CO, non-methane hydrocarbon （NMHC） and ambient particle number concentrations as well as modeled photolysis frequencies obtained from measurements. The maximum midday sulphuric acid concentrations vary from 4.53 × 10^7 to 2.17 × 10^8 molecules cm^-3, the corresponding source rate via reaction of OH and SO2 range between 2.37 × 10^6 and 1.16 × 10^7 molecules cm^-3 s^-1. Nucleation mode growth rate was derived from size spectral evolution during the events to be 6.8-13.8 nm h^-1. Based on the growth rate, concentration of the vapors participating in subsequent growth were estimated to vary from 1.32 × 10^8 to 2.80 × 10^8 molecules cm^-3 with corresponding source rate between 7.26 × 10^6 and 1.64 × 10^7 molecules cm^-3 s^-1. Our results show the degree of pollution is larger in PRD. Sulphuric acid concentrations are fairly high and have a close correlation with new particle formation events. Budget analysis shows that sulphuric acid alone is not enough for required growth; other nonvolatile vapors are needed. However, sulphuric acid plays an important role in growth; the contribution of sulphuric acid to growth in PRD is 12.4%-65.2%.

Water Production by Condensation of Wet Air

It is now assumed that climate warming is effective and noticeable. It not only leads to a lack of water that is increasing in desert areas, but it must be kept in mind that the inhabitants of the villages located in the geographical areas whose access to water is difficult, make binding efforts to gain access to water. This article proposes to present the possibility of obtaining water by the condensation of the water vapors of the air by applying the thermodynamic processes of the humid air as well as those of the refrigerating installations. In fact, atmospheric air contains suspended water vapors. When this steam cools below its rose point, there is condensation if water vapors and liquid water or ice appears. It was obtained a quantity of condensed vapors in a refrigeration facility. This amount is directly proportional to the refrigeration power whose efficiency can be improved by the use of photovoltaic energy given the reduced financial cost of this energy. This seems to be a hope among the possible solutions to be considered for the resolution of the water issue.

Estimation of the minimum miscibility pressure for CO_(2)ecrude-oil systems by molecular dynamics simulation

CO_(2)injection is an effective enhanced oil recovery technique for energy security with the benefits of carbon neutrality.To reach the maximum oil recovery,the miscible condition between CO_(2)and oil needs to be maintained in the reservoir,which requires the operation pressure to be higher than the minimum miscibility pressure(MMP).There are two types of MMPs:the first-contact MMP(FC-MMP)and the multi-contact MMP(MC-MMP).In this study,molecular dynamics simulations were performed for the CO_(2)eoil interface system using two simplified digital oil models:a Bakken dead oil with four lumping components and a live-crude-oil model with 50 types of oil molecules but with no asphaltenes and heavy oil fractions.The vanishing interfacial tension method was used to predict the MMP.Different CO_(2)eoil volume ratios were considered to mimic the different degrees of vaporization.To estimate the MMP accurately and rapidly,the interfacial tension in the low-pressure regime was used for the prediction.Consequently,different MMPs were obtained,where the MMP value increased with increasing CO_(2)eoil volume ratio.FC-MMP can be predicted when the CO_(2)eoil volume ratio is sufficiently high.When the CO_(2)eoil volume ratio was approximately 9e10,MMP was closest to the actual MC-MMP value.The condensing and vaporizing mechanism was also studied at the molecular scale.Because pure CO_(2)was used,only the vaporizing effect on MMP occurred.It was found that the intermediate C2eC6 components have the main effect on the MMP calculation.This study can help to establish a computational protocol to estimate FC-MMP and MC-MMP,which are widely used in reservoir engineering.

Synthesis and Characterization of SiO_2 Coated γ-Fe_2O_3 Nanocomposite Powder for Hyperthermic Application

SiO2 coated γ-Fe2O3 nanocomposite powder has been successfully synthesized by chemical vapor condensation process and its feasibility on hyperthermic application was investigated in this study. The power loss of SiO2 coated γ-Fe2O3 nanocomposite powder which means the magnetic heating effect under alternative magnetic field was much higher than the single phase γ-Fe2O3 nano powder due to the very fine size under 20 nm and well dispersion in biologically compatible SiO2 matrix. The superparamagnetism and hyperthermic property of SiO2 coated γ-Fe2O3 nanocomposite powder were discussed in terms of microstructural development in this study.