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91.
Airborne nanoparticle exposures associated with the manual handling of nanoalumina and nanosilver in fume hoods 总被引:1,自引:1,他引:0
Su-Jung Tsai Earl Ada Jacqueline A. Isaacs Michael J. Ellenbecker 《Journal of nanoparticle research》2009,11(1):147-161
Manual handling of nanoparticles is a fundamental task of most nanomaterial research; such handling may expose workers to
ultrafine or nanoparticles. Recent studies confirm that exposures to ultrafine or nanoparticles produce adverse inflammatory
responses in rodent lungs and such particles may translocate to other areas of the body, including the brain. An important
method for protecting workers handling nanoparticles from exposure to airborne nanoparticles is the laboratory fume hood.
Such hoods rely on the proper face velocity for optimum performance. In addition, several other hood design and operating
factors can affect worker exposure. Handling experiments were performed to measure airborne particle concentration while handling
nanoparticles in three fume hoods located in different buildings under a range of operating conditions. Nanoalumina and nanosilver
were selected to perform handling experiments in the fume hoods. Air samples were also collected on polycarbonate membrane
filters and particles were characterized by scanning electron microscopy. Handling tasks included transferring particles from
beaker to beaker by spatula and by pouring. Measurement locations were the room background, the researcher’s breathing zone
and upstream and downstream from the handling location. Variable factors studied included hood design, transfer method, face
velocity/sash location and material types. Airborne particle concentrations measured at breathing zone locations were analyzed
to characterize exposure level. Statistics were used to test the correlation between data. The test results found that the
handling of dry powders consisting of nano-sized particles inside laboratory fume hoods can result in a significant release
of airborne nanoparticles from the fume hood into the laboratory environment and the researcher’s breathing zone. Many variables
were found to affect the extent of particle release including hood design, hood operation (sash height, face velocity), work
practices, type and quantity of the material being handled, room conditions, and the adequacy of the room exhaust.
相似文献
Su-Jung (Candace) TsaiEmail: |
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Glycoluril‐Derived Molecular Clips are Potent and Selective Receptors for Cationic Dyes in Water 下载免费PDF全文
Prof. Dr. Nengfang She Dr. Damien Moncelet Dr. Laura Gilberg Dr. Xiaoyong Lu Prof. Dr. Vladimir Sindelar Prof. Dr. Volker Briken Prof. Dr. Lyle Isaacs 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(43):15270-15279
Molecular clip 1 remains monomeric in water and engages in host–guest recognition processes with suitable guests. We report the Ka values for 32 1? guest complexes measured by 1H NMR, UV/Vis, and fluorescence titrations. The cavity of 1 is shaped by aromatic surfaces of negative electrostatic potential and therefore displays high affinity and selectivity for planar and cationic aromatic guests that distinguishes it from CB[n] receptors that prefer aliphatic over aromatic guests. Electrostatic effects play a dominant role in the recognition process whereby ion–dipole interactions may occur between ammonium ions and the C=O groups of 1 , between the SO3? groups of 1 and pendant cationic groups on the guest, and within the cavity of 1 by cation–π interactions. Host 1 displays a high affinity toward dicationic guests with large planar aromatic surfaces (e.g. naphthalene diimide NDI+ and perylene diimide PDI+) and cationic dyes derived from acridine (e.g. methylene blue and azure A). The critical importance of cation–π interactions was ascertained by a comparison of analogous neutral and cationic guests (e.g. methylene violet vs. methylene blue; quinoline vs. N‐methylquinolinium; acridine vs. N‐methylacridinium; neutral red vs. neutral red H+) the affinities of which differ by up to 380‐fold. We demonstrate that the high affinity of 1 toward methylene blue (Ka=3.92×107 m ?1; Kd=25 nm ) allows for the selective sequestration and destaining of U87 cells stained with methylene blue. 相似文献
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From Packed “Sandwich” to “Russian Doll”: Assembly by Charge‐Transfer Interactions in Cucurbit[10]uril 下载免费PDF全文
Wanjun Gong Xiran Yang Peter Y. Zavalij Prof. Lyle Isaacs Dr. Zhiyong Zhao Prof. Simin Liu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(49):17612-17618
As the host possessing the largest cavity in the cucurbit[n]uril (CB[n]) family, CB[10] has previously displayed unusual recognition and assembly properties with guests but much remains to be explored. Herein, we present the recognition properties of CB[10] toward a series of bipyridinium guests including the tetracationic cyclophane known as blue box along with electron‐rich guests and detail the influence of encapsulation on the charge‐transfer interactions between guests. For the mono‐bipyridinium guest (methylviologen, MV 2+), CB[10] not only forms 1:1 and 1:2 inclusion complexes, but also enhances the charge‐transfer interactions between methylviologen and dihydroxynaphthalene ( HN ) by mainly forming the 1:2:1 packed “sandwich” complex (CB[10] ? 2 MV 2+ ?HN ). For guest 1 with two bipyridinium units, an interesting conformational switching from linear to “U” shape is observed by adding catechol to the solution of CB[10] and the guest. For the tetracationic cyclophane‐blue box, CB[10] forms a stable 1:1 inclusion complex; the two bipyridinium units tilt inside the cavity of CB[10] according to the X‐ray crystal structure. Finally, a supramolecular “Russian doll” was built up by threading a guest through the cavities of both blue box and CB[10]. 相似文献
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Joseph P. Y. Kao Stephen T. Isaacs John E. Hearst 《Photochemistry and photobiology》1990,51(3):273-283
UV irradiation of 4'-hydroxymethyl-4,5',8-trimethyl psoralen (HMT) in aqueous solution yields three major photoproducts. We have isolated and characterized (1) a cyclobutane-bridged dimer in which a cis-syn linkage occurs between the furan end of one HMT moiety and the pyrone end of the other; (2) a cyclobutane-bridged dimer wherein both HMT moieties are linked at their pyrone ends with probable cis-syn configuration; and (3) an isomer of HMT for which we have proposed a structure in which the furan and pyrone ring oxygens assume a para orientation via photoisomerization. 相似文献
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We report the operation and performance of a near-infrared, synchronously-pumped mode locked dye laser, pumped with the 647.1 nm line of a mode locked krypton ion laser. The output pulses are as short as 3.2 ps in duration, and can be tuned from 750 to 910 nm with an intercavity three plate birefringent filter. 相似文献