In this letter,Fe_2O_3 UFP(Ultrafine Particles)hydrosol and organosol with high third order optical nonlinear susceptibility(3)have been reported for the first time. The surfacial modification of Fe_2O_3 UFP with dode...In this letter,Fe_2O_3 UFP(Ultrafine Particles)hydrosol and organosol with high third order optical nonlinear susceptibility(3)have been reported for the first time. The surfacial modification of Fe_2O_3 UFP with dodecylbenzenesulfonate ions(DBS)can enhance the nonlinear optical response through interfacial confinement of electron motion. The involved mechanism is discussed.展开更多
The high purity of ultrafine power (UFP )of a-luminiitm nitride(AlN) are prepared by the reaction of nitrogen plasma with metal aluminium in D. C. plasma reactr. Both the nitriding principle and the AIN nucleation mec...The high purity of ultrafine power (UFP )of a-luminiitm nitride(AlN) are prepared by the reaction of nitrogen plasma with metal aluminium in D. C. plasma reactr. Both the nitriding principle and the AIN nucleation mechanism are stud-ied. The results indicate that the chemical reaction in the forma-tion process of AIN UFP is -very complicated and the nitriding reaction is corelated to the concentration of reactants and the temperature. The particle size cav be adjusted by controlling the partial pressure of the reactants,the temperature and the react-ing rate.展开更多
Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is fea...Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is featured by its hish specific surface area, large pore volume, small perticle size and low bulk density.展开更多
Nowadays, many people work in an office environment. Air pollutants, including particles and gases, are generated by humans and by different devices that are used in offices. Pollutants can also enter an office room w...Nowadays, many people work in an office environment. Air pollutants, including particles and gases, are generated by humans and by different devices that are used in offices. Pollutants can also enter an office room with the air supplied from outdoors. It has been established that air pollutants have adverse health effects on human body. Air cleaning devices are commonly marketed as being beneficial for the health by removing air pollutants and consequently improving indoor air quality. The performance of five air cleaning technologies was tested in order to determine the generation of ozone and particles in an office room. The particle removal effectiveness of the technologies was also determined in order to clarify their ability to remove UFPs （ultrafine particles） in the office room. The tested five air cleaning technologies are non-thermal plasma, corona discharge ionizer, portable air purifier, electrostatic fibrous filter and three-dimensional fibrous filter. The interior surfaces of the office room emit low levels of volatile organic compounds, since the office room has not been refurbished for about two decades. The results showed that the particle removal effectiveness of the technologies was ranged between 0.2 and 0.45 for the office room. The three technologies using/generating ozone significantly increased the ozone level in the office room. However, no increase of the UFP concentration was detected.展开更多
Indoor air quality(IAQ) directly affects the health of occupants. Household manufacturing equipment(HME) used for hobbies or educational purposes is a new and unexplored source of air pollution. In this study, we eval...Indoor air quality(IAQ) directly affects the health of occupants. Household manufacturing equipment(HME) used for hobbies or educational purposes is a new and unexplored source of air pollution. In this study, we evaluated the characteristics of particulate and gaseous pollutants produced by a household laser processing equipment(HLPE). Various target materials were tested using a commercial HLPE under various operating conditions of laser power and sheath air flow rate. The mode diameters of the emitted particles gradually decreased as laser power increased, while the particle number concentration(PNC) and particle emission rate(PER) increased. In addition, as the sheath air flow rate quadrupled from 10 to 40 L/min, the mode diameter of the emitted particles decreased by nearly 25%, but the effect on the PNC was insignificant. When the laser induced the target materials at 53 m W, the mode diameters of particles were < 150 nm, and PNCs were > 2.0 × 10^(4) particles/cm^(3). Particularly, analyses of sampled aerosols indicated that harmful substances such as sulfur and barium were present in particles emitted from leather. The carcinogenic gaseous pollutants such as acrylonitrile, acetaldehyde, 1,3-butadiene, benzene, and C 8 aromatics(ethylbenzene) were emitted from all target materials. In an actual indoor environment, the PNC of inhalable ultrafine particles(UFPs) was > 5 × 10^(4) particles/cm^(3) during 30 min of HLPE operation. Our results suggest that more meticulous control methods are needed, including the use of less harmful target materials along with filters or adsorbents that prevent emission of pollutants.展开更多
基金This project is sponsored by National Science Fundation.
文摘In this letter,Fe_2O_3 UFP(Ultrafine Particles)hydrosol and organosol with high third order optical nonlinear susceptibility(3)have been reported for the first time. The surfacial modification of Fe_2O_3 UFP with dodecylbenzenesulfonate ions(DBS)can enhance the nonlinear optical response through interfacial confinement of electron motion. The involved mechanism is discussed.
文摘The high purity of ultrafine power (UFP )of a-luminiitm nitride(AlN) are prepared by the reaction of nitrogen plasma with metal aluminium in D. C. plasma reactr. Both the nitriding principle and the AIN nucleation mechanism are stud-ied. The results indicate that the chemical reaction in the forma-tion process of AIN UFP is -very complicated and the nitriding reaction is corelated to the concentration of reactants and the temperature. The particle size cav be adjusted by controlling the partial pressure of the reactants,the temperature and the react-ing rate.
文摘Ultrafine particle (UFP)alumina has been prepared by supereritical fluid drying process of inorganic salt with organic solvent system, which is reported for the first time. UFP-alumina prepared from this system is featured by its hish specific surface area, large pore volume, small perticle size and low bulk density.
文摘Nowadays, many people work in an office environment. Air pollutants, including particles and gases, are generated by humans and by different devices that are used in offices. Pollutants can also enter an office room with the air supplied from outdoors. It has been established that air pollutants have adverse health effects on human body. Air cleaning devices are commonly marketed as being beneficial for the health by removing air pollutants and consequently improving indoor air quality. The performance of five air cleaning technologies was tested in order to determine the generation of ozone and particles in an office room. The particle removal effectiveness of the technologies was also determined in order to clarify their ability to remove UFPs （ultrafine particles） in the office room. The tested five air cleaning technologies are non-thermal plasma, corona discharge ionizer, portable air purifier, electrostatic fibrous filter and three-dimensional fibrous filter. The interior surfaces of the office room emit low levels of volatile organic compounds, since the office room has not been refurbished for about two decades. The results showed that the particle removal effectiveness of the technologies was ranged between 0.2 and 0.45 for the office room. The three technologies using/generating ozone significantly increased the ozone level in the office room. However, no increase of the UFP concentration was detected.
基金supported by a grant from the National Research Foundation of Korea(NRF)funded by the Ministry of Science ICT and Future Planning of Korea(No.2019R1A2C2002398)partially supported by the Alchemist Project(No.20012263)funded by the Ministry of Trade,Industry&Energy of Korea,the KIST Institutional Programthe Sejong University Program(No.20200392)。
文摘Indoor air quality(IAQ) directly affects the health of occupants. Household manufacturing equipment(HME) used for hobbies or educational purposes is a new and unexplored source of air pollution. In this study, we evaluated the characteristics of particulate and gaseous pollutants produced by a household laser processing equipment(HLPE). Various target materials were tested using a commercial HLPE under various operating conditions of laser power and sheath air flow rate. The mode diameters of the emitted particles gradually decreased as laser power increased, while the particle number concentration(PNC) and particle emission rate(PER) increased. In addition, as the sheath air flow rate quadrupled from 10 to 40 L/min, the mode diameter of the emitted particles decreased by nearly 25%, but the effect on the PNC was insignificant. When the laser induced the target materials at 53 m W, the mode diameters of particles were < 150 nm, and PNCs were > 2.0 × 10^(4) particles/cm^(3). Particularly, analyses of sampled aerosols indicated that harmful substances such as sulfur and barium were present in particles emitted from leather. The carcinogenic gaseous pollutants such as acrylonitrile, acetaldehyde, 1,3-butadiene, benzene, and C 8 aromatics(ethylbenzene) were emitted from all target materials. In an actual indoor environment, the PNC of inhalable ultrafine particles(UFPs) was > 5 × 10^(4) particles/cm^(3) during 30 min of HLPE operation. Our results suggest that more meticulous control methods are needed, including the use of less harmful target materials along with filters or adsorbents that prevent emission of pollutants.
