The hydrolytic disproportionation of gaseous NO 2 on water's surface (2 NO 2 + H 2 O -HONO + NO 3 À + H + ) (R1) has long been deemed to play a key, albeit unquantifiable role in tropospheric chemistry. We recently found that (R1) is dramatically accelerated by anions in experiments performed on aqueous microjets monitored by online electrospray mass spectrometry. This finding let us rationalize unresolved discrepancies among previous laboratory results and suggested that under realistic environmental conditions (R1) should be affected by everpresent surfactants. Herein, we report that NO 2 (g) uptake is significantly enhanced by cationic surfactants, weakly inhibited by fulvic acid (FA, a natural polycarboxylic acid) and anionic surfactants, and unaffected by 1-octanol. Surfactants appear to modulate interfacial anion coverage via electrostatic interactions with charged headgroups. We show that (R1) should be the dominant mechanism for the heterogeneous conversion of NO 2 (g) to HONO under typical atmospheric conditions throughout the day. The photoinduced reduction of NO 2 into HONO on airborne soot might play a limited role during daytime.

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Photodissociation of amorphous ice films of carbon dioxide and water co-adsorbed at 90 K was carried out at 157 nm using oxygen-16 and -18 isotopomers with a time-of-flight photofragment mass spectrometer. O((3)P(J)) atoms, OH (v = 0) radicals, and CO (v = 0,1) molecules were detected as photofragments. CO is produced directly from the photodissociation of CO(2). Two different adsorption states of CO(2), i.e., physisorbed CO(2) on the surface of amorphous solid water and trapped CO(2) in the pores of the film, are clearly distinguished by the translational and internal energy distributions of the CO molecules. The O atom and OH radical are produced from the photodissociation of H(2)O. Since the absorption cross section of CO(2) is smaller than that of H(2)O at 157 nm, the CO(2) surface abundance is relatively increased after prolonged photoirradiation of the mixed ice film, resulting in the formation of a heterogeneously layered structure in the mixed ice at low temperatures. Astrophysical implications are discussed.

Nanosecond laser ablation and subsequent ion formation processes of submicron aerosol particles containing multicomponent ammonium and sodium salts relevant to atmospheric aerosols were studied using a laser-ionization single-particle aerosol mass spectrometer. In the case of ammonium salts, chemical species with a low ionization energy are predominately observed in the positive-ion mass spectra, while those having a high electron affinity are predominately observed in the negative-ion mass spectra. Dissociative electron attachment processes take place. However, as far as sodium salts are concerned, the energetically preferred ions are not necessarily dominant, and the ion formation processes are suggested to be more complex than the ammonium salts.

The objective of this study is to develop the variable control mechanism to amplify the operating range of the end-effector of the wearable haptic device. The conventional haptic devices are classified into passive haptic devices and active haptic devices by means of the force display conditions. The passive haptic device has a wide operating range and a high bandwidth of the dynamic characteristics in the force non-displayed condition. On the other hand, the active haptic device provides accurate resistive force for the operator by changing the posture of the device by the active actuators. In this study, the variable control mechanism which has both of these advantages is developed. The proposed mechanism is able to control the mechanical connection between the active actuator and the end effector of the haptic device. In addition, the force detection mechanism and the angle detection mechanism of the wrist for the force feedback control are developed to display an accurate force. The experiments of the transition between the unconstraint condition and the constraint condition of the end effector were carried out to confirm the effectiveness of the variable control mechanism. The experimental results show that the proposed haptic device with the proposed mechanism is able to improve the dynamic characteristics of the end-effector and to amplify the operating range of the end-effector of the wearable haptic device.