Global Traffic in Television

They Love Lucy and get high on Gunsmoke in Mexico City, Belgrade, and Kuala Lumpur. A benchmark survey of the buying and selling of TV programs in 50 countries     

Design of digital filters with maximally flat passband and equiripple stopband magnitude

This paper introduces a general class of digital filters with maximally flat passband magnitude, equiripple stopband magnitude, and different order numerator and denominator. the classical Chebyschev type II (inverse Chebyschev) filters having equal numerator and denominator orders are considered as special members of this filter class. the filter types to be considered are lowpass, highpass and bandpass. the proposed filter class consists both of filters having all the zeros on the unit circle and of filters having some zeros off the unit circle to contribute to the passband shaping. An efficient iterative algorithm for the design of filters of the given type is presented. It is based on shaping the passband and stopband responses alternately until the difference between successive solutions is within given tolerance limits. Several comparisons show that in wideband applications filters with numerator order higher than denominator order present considerable advantages over equivalent Chebyschev type II designs, in terms of multiplication rate and/or frequency selectivity. In narrowband applications, in turn, filters with higher denominator order are shown to be the most effective.     

Performance of SU-8 microchips as separation devices and comparison with glass microchips

Effective analytical performance of native, all-SU-8 separation microdevices is addressed by comparing their performance to commercial glass microdevices in microchip zone electrophoresis accompanied by fluorescence detection. Surface chemistry and optical properties of SU-8 microdevices are also examined. SU-8 was shown to exhibit repeatable electroosmotic properties in a wide variety of buffers, and SU-8 microchannels were successfully utilized in peptide and protein analyses without any modification of the native polymer surface. Selected, fluorescent labeled, biologically active peptides were baseline resolved with migration time repeatability of 2.3-3.6% and plate numbers of 112,900-179,800 m(-1). Addition of SDS (0.1%) or SU-8 developer (1.0%) to the separation buffer also enabled protein analysis by capillary zone electrophoresis. Plate heights of 2.4-5.9 microm were obtained for fluorescent labeled bovine serum albumin. In addition, detection sensitivity through SU-8 microchannels was similar to that through BoroFloat glass, when fluorescence illumination was provided at visible wavelengths higher than 500 nm. On the whole, the analytical performance of SU-8 microchips was very good and fairly comparable to that of commercial glass chips as well as that of traditional capillary electrophoresis and chromatographic methods. Moreover, lithography-based patterning of SU-8 enables straightforward integration of multiple functions on a single chip and favors fully microfabricated lab-on-a-chip systems.     

Optical detection of the anesthetic agent propofol in the gas phase

The anesthetic agent propofol (2,6-diisopropylphenol) is the most widely used intravenously administered drug in general anesthesia. However, a viable online capability to monitor metabolized levels of propofol in patients does not currently exist. Here we show for the first time that optical spectroscopy has good potential to detect metabolized propofol from patients' exhaled breath. We present quantitative absorption measurements of gas phase propofol both in the ultraviolet and middle-infrared spectral regions. We demonstrate that a detection limit in the subparts-per-billion concentration range can be reached with photoacoustic spectroscopy in the UV spectral region, paving the way for the development of future optical monitors.     

Acid catalytic effects in the chlorination of propanoic acid

Selective α‐chlorination of propanoic acid to form 2‐monochloropropanoic (MCA) and 2,2‐dichloropropanoic acid (DCA) was investigated in a laboratory‐scale, semibatch reactor at 90–130 °C at atmospheric total pressure and in the presence of chlorosulfonic acid (ClSO₃H) and 2,2‐dichloroethanoic acid (DCA′) as catalytic agents and oxygen as a radical scavenger. The decomposition of the catalyst was investigated with sulfur analysis and UV‐spectrometry. The studies revealed that the majority of sulfur remains in the reaction mixture, but is converted to an inactive form during the chlorination. The reasons may be the decomposition of ClSO₃H and its reaction with propanoic acid. The kinetic experiments revealed autocatalytic and parallel formation of MCA and DCA, the selectivity being independent of Cl₂ concentration in the liquid phase. The experiments with DCA′ also demonstrated that DCA′ has a catalytic effect on the chlorination The experiments confirmed the validity of a previously proposed reaction scheme for α‐chlorination, which comprises the formation of the reaction intermediate (propanoyl chloride) from propanoic acid and ClSO₃H, the acid‐catalyzed enolization of the acid and a hydroxyl‐chlorine exchange reaction. The acid‐catalyzed enolization is the rate determining step in the reaction sequence. The kinetic data were fitted to rate equations based on the reaction scheme. © 2000 Society of Chemical Industry     

Acoustic Properties of Aerogels: Current Status and Prospects

Noise reduction remains an important priority in the modern society, in particular, for urban areas and highly populated cities. Insulation of buildings and transport systems such as cars, trains, and airplanes has accelerated the need to develop advanced materials. Various porous materials, such as commercially available foams and granular and fibrous materials, are commonly used for sound mitigating applications. In this review, a special class of advanced porous materials, aerogels, is examined, and an overview of the current experimental and theoretical status of their acoustic properties is provided. Aerogels can be composed of inorganic matter, synthetic or natural polymers, as well as organic/inorganic composites and hybrids. Aerogels are highly porous nanostructured materials with a large number of meso- and small macropores; the mechanisms of sound absorption partly differ from those of traditional porous absorbers possessing large macropores. The understanding of the acoustic properties of aerogels is far from being complete, and experimental results remain scattered. It is demonstrated that the structure of the aerogel provides a complex three-dimensional architecture ideally suited for promising high-performance materials for acoustic mitigation systems. This is in addition to the numerous other desirable properties that include low density, low thermal conductivity, and low refractive index.