Natural chlorine and fluorine in the atmosphere, water and precipitation

The geochemical cycles of chlorine and fluorine are surveyed and summarized as framework for the understanding of the global natural abundances of these species in the atmosphere, water, and precipitation. In the cycles the fluxes into and out of the atmosphere can be balanced within the limits of our knowledge of the natural sources and sinks. Sea salt from the ocean surfaces represent the predominant portion of the source of chlorine. It is also an important source of atmospheric fluorine, but volcanoes are likely to be more important fluorine sources. Dry deposition of sea salt returns about 85 percent of the salt released there. Precipitation removes the remainder. Most of the sea salt materials are considered to be cyclic, moving through sea spray over the oceans and either directly back to the oceans or deposited dry and in precipitation on land, whence it runs off into rivers and streams and returns to the oceans. Most of the natural chlorine in the atmosphere is in the form of particulate chloride ion with lesser amounts as gaseous inorganic chloride and methyl chloride vapor. Fluorine is emitted from volcanoes primarily as HF. It is possible that HF may be released directly form the ocean surface but this has not been confirmed by observation. HCl and most likely HF gases are released into the atmosphere by sea salt aerosols. The mechanism for the release is likely to be the provision of protons from the so-called excess sulfate and HNO3. Sea salt aerosol contains fluorine as F(-), MgF(+), CaF(+), and NaF. The concentrations of the various species of chlorine and fluorine that characterize primarily natural, unpolluted atmospheres are summarized in tables and are discussed in relation to their fluxes through the geochemical cycle

Foreword: The Rocky Road Toward the Rule of Law in China: 1979-2000

This Twentieth Anniversary Issue of JILB again has a symposium on law in China entitled China Revisited: Examining the Rule of Law After Twenty Years. The impetus for the 2000 China Symposium is the unprecedented integration of China into the world economic community, evidenced by China\u27s imminent entry into the World Trade Organization ( WTO ).2 The road to China\u27s integration into the WTO was paved by the U. S. Senate\u27s recent vote, the most significant advance in U.S.-China relations since President Nixon\u27s 1972 visit,\u2713 which grants China permanent normalized trade relations without annual Congressional review. Although the Senate approval was expected, the overwhelming margin of 83 to 15 was not, highlighting the fact that a strong majority of legislators and Americans support normal and mutually productive commercial relations with the PRC. With China still at the forefront of vital issues relating to international law and commerce, no topic is more pressing and appropriate to mark JILB\u27s twenty years of publication than a second symposium addressing the evolution of the rule of law in China and its impact on commercial transactions with China

Foreword: The Rocky Road Toward the Rule of Law in China: 1979-2000

This Twentieth Anniversary Issue of JILB again has a symposium on law in China entitled China Revisited: Examining the Rule of Law After Twenty Years. The impetus for the 2000 China Symposium is the unprecedented integration of China into the world economic community, evidenced by China\u27s imminent entry into the World Trade Organization ( WTO ).2 The road to China\u27s integration into the WTO was paved by the U. S. Senate\u27s recent vote, the most significant advance in U.S.-China relations since President Nixon\u27s 1972 visit,\u2713 which grants China permanent normalized trade relations without annual Congressional review. Although the Senate approval was expected, the overwhelming margin of 83 to 15 was not, highlighting the fact that a strong majority of legislators and Americans support normal and mutually productive commercial relations with the PRC. With China still at the forefront of vital issues relating to international law and commerce, no topic is more pressing and appropriate to mark JILB\u27s twenty years of publication than a second symposium addressing the evolution of the rule of law in China and its impact on commercial transactions with China

Observation and Analysis of Surface Acoustic Wave Induced Atomization

The ability to excite instabilities in free fluid surfaces via acoustic excitation is well known, even to the point of atomization. Surprisingly, atomization phenomena exist at frequencies up to 1 GHz, because peak piezoelectrically-driven vibration velocities remain remarkably constant at about 1 m/s regardless of the excitation frequency if one makes use of different materials and vibration modes along the way. At 100 MHz, for example, we have maintained surface acoustic waves 1 m/s vibration velocity and measured displacements and accelerations of 10 nanometers and 10 million m/s2. At these extreme conditions, fluid microfilaments, multiscale droplet formation, and other curious phenomena appear. Understanding the behaviour is important for applications in rheology and the study of solid-fluid interactions on the micro and nanoscale, and we illustrate methods for observation of the atomization and vibration conduction processes under these conditions

Rapid and Accurate Pressure Sensing Device for Direct Measurement of Intraocular Pressure.

PurposeIntraocular pressure (IOP) is the primary modifiable risk factor for glaucoma. Current devices measure IOP via the dynamic response of the healthy cornea and do not provide the accurate IOP measurements for patients with altered corneal biomechanics. We seek to develop and test an accurate needle-based IOP measurement device that is not cornea dependent.MethodsOur device combines a high-resolution pressure microsensor with 30- and 33-gauge Luer lock needles to provide IOP measurements via a microcontroller and USB interface to a computer. The device was calibrated in a membrane chamber and then tested and validated in the anterior chamber and post-vitrectomy vitreous chamber of rabbit eyes. The results were compared to Tonopen readings across a pressure range of 0 to 100 mm Hg, imposed in increments of 10 mm Hg.ResultsBoth the needle based sensor device and the Tonopen demonstrated a linear relationship with changes in imposed pressure. The Tonopen was found to consistently underestimate the IOP both in the anterior and vitreous chambers. The Tonopen exhibited a significantly greater error than our needle-based sensor device. With increased pressure (>30 mm Hg), the error of the Tonopen increased, whereas the error of our device did not. The 30-gauge needle produces an insignificant improvement in accuracy over the 33-gauge needle.ConclusionsA needle-based sensor device enables accurate IOP measurements over a broad range of induced IOP.Translational relevanceDirect measurement of IOP in the anterior chamber circumvents the influence of corneal parameters on IOP measurement

Unraveling the complex dynamics of acoustofluidics

We describe a novel mathematical formalism for analysis and modeling of these acoustofluidic systems. The framework provides the user greater generality than classical methods through articulation and direct exploitation of spatiotemporal scale disparities present between the acoustics and remaining dynamics via multiscale differential operations. This is a leap forward from the classical theories Rayleigh first established nearly one hundred fifty years ago. The method is applied to well-known classical problems of semi-infinite extent defined by particle and streaming velocities possessing similar magnitudes: the ``fast streaming'' condition. The compressible Navier-Stokes equations are solved in an approximate, successive manner, and acoustic and streaming field equations are obtained. The latter implicitly provides a succinct physical origin for observed layering phenomenon in bulk streaming flows, as discussed in detail in [see co-article]. We analytically obtain closed-form equations that explain fast steady-state bulk streaming. The foregoing results are used to derive a non-constitutive upper bound on the energetic conversion efficiency of the driving acoustics to the resultant maximum streaming flow magnitude. Ample comparison is made to the classic literature and theories to connect this work to past efforts by many authors. Rigorous validation is obtained over a broad survey of experimental findings from the recent literature.Comment: main article: 18 pages, 8 figures; supplemental material: 4 pages, 2 figure