Madep (Switzerland)

Microbacterium sp. strain BR1 is a bacterial strain that recently received attention for its capability to mineralize sulfamethoxazole (SMX) and other sulfonamides. In this study, the survival of Microbacterium sp. in municipal sludge waters was tested in batch experiments to explore optimal process conditions. Inoculation of Microbacterium sp. was subsequently performed in a pilot membrane bioreactor (MBR) operated in two configurations: treating full-scale MBR permeate (post-treatment) and treating raw municipal wastewater. SMX removal by Microbacterium sp. could not be proved in any of the configurations, except for SMX concentrations far higher than the ones normally found in municipal wastewater. By use of molecular tools (fluorescence in situ hybridization analysis) a low capability to survive in activated sludge systems was assessed. After inoculation, Microbacterium sp. was reduced to a small fraction of the viable biomass. The observed growth rate appeared to be many times lower than the one of typical activated sludge micro-organisms. Possibilities of application in full-scale municipal wastewater treatment are scarce.

A new method for the design of relatively narrowband ladder-type SAW filters is proposed. It consists of the thinning procedure and consecutive randomization of positions of the remaining transductive periods inside the IDT to suppress undesirable additional passbands. A 0.9% fractional bandwidth filter on LiTaO(3) 42°-cut was designed and manufactured using the proposed approach.

Surface acoustic wave (SAW) radio-frequency identification (RFID) tags are encoded according to partial reflections of an interrogation signal by short metal reflectors. The standard encryption method involves time position encoding that uses time delays of response signals. However, the data capacity of a SAW RFID tag can be significantly enhanced by extracting additional phase information from the tag responses. In this work, we have designed, using FEM-BEM simulations, and fabricated, on 128deg-LiNbO3, inline 2.44-GHz SAW RFID tag samples that combine time position and phase encoding: each reflective echo has four possible time positions and, additionally, a phase of 0deg, -90deg, -180deg, or -270deg. This corresponds to 16 different states, i.e., 4 bits of data, per code reflector. In addition to the enhanced data capacity, our samples also exhibit a low loss level of -38 dB for code reflections.

Rayleigh wave side radiation from a synchronous 1.6 GHz longitudinal leaky SAW (LLSAW) resonator on YZ-LiNbO3 substrate is studied in this paper. Acoustic wave fields measured from the LLSAW resonator using a scanning laser interferometer are presented. The radiation angles extracted from the interferometric measurements are compared to theoretical calculations in a wide frequency range. Furthermore, the relative strength of the escaping Rayleigh wave beams evaluated from the interferometric measurements as a function of frequency is compared to the calculated coupling strength. These measurements reveal interesting effects not observed earlier. While the number of beams, the angles of radiation and their dependence on frequency can be reasonably explained, there are other effects whose explanation remains uncertain.

It is well known that the propagation loss in wave cuts on LiTaO3 and LiNbO3 depends on the geometry of Al electrodes. According to K. Hashimoto et al. [1997] the widely used cut of 36deg-LiTaO3 optimal for zero thickness of metal fingers was replaced by 42degLiTaO3 for Al electrodes with h/lambda=8% . Here we demonstrate theoretically that by introducing thin film (hdiel/lambda = 1%to 3%) sub-layer of hard material such as TiO2 many combinations of cuts and Al electrode thickness can be optimised [Plessky, et al., 2003] in terms of minimization of propagation loss resulting from leakage of SAW energy into bulk by slow shear waves. High dielectric permittivity of mentioned materials is necessary to minimize the loss of coupling caused by separation of electrodes from the piezoelectric. For example, with sub-layer of 1.5% of TiO2 classic 36deg cut of LiTaO3 , according to this simulations, will show minimal leaky loss with 8% thick Al electrodes. Moreover, rarely used cut of 41deg-LiNbO 3, having substantial leaky losses but extremely strong coupling, can be transformed into zero loss substrate with 2.5% thick TiO2 layer and 7.5% Al electrodes on top of it. The proposed method allows to get low propagation loss on substrate with desired coupling coefficient, which makes the design of low loss filters more flexible

We consider the interaction of surface acoustic waves (SAWs) with short electrode gratings encompassing only few electrodes on 128/spl deg/ lithium niobate (LiNbO/sub 3/). The qualifications of the reflectors are evaluated by comparing the part of incident SAW energy scattered by the structure into the bulk to the energy reflected back as a SAW.

A single-phase unidirectional transducer (SPUDT) structure using lambda/4 and wider electrodes is introduced. The considerable difference between the reflectivity of short-circuited lambda/4 electrodes and that of floating lambda/2-wide electrodes on 128 degree lithium niobate (LiNbO3) is exploited. The surface acoustic wave (SAW) device operating at 2.45 GHz has critical dimensions of about 0.4 microm, accessible for standard optical lithography.

In the past few years a new class of SAW devices has been under development based on the use of one port SAW resonators as lumped elements with their impedance strongly changing in a frequency range of effective SAW excitation. These 'SAW impedance elements' can be connected in ladder type, balanced bridge type, or others types of networks to provide desired filter characteristics. In this paper the admittance characteristics of a single element are analyzed using coupling of mode (COM) model simulations. It is found that resonant type characteristics of a long transducer can be described by very simple formulas. The frequency gap between resonance and anti-resonance, important for filter design, is determined practically by the /spl Delta/V/V parameter of the piezoelectric substrate used, while the minimum magnitude of the impedance at the resonant frequency is determined by the SAW attenuation. The internal reflections only shift the resonance to the left edge of the stopband not changing other characteristics. A case of a synchronous resonator comprising a relatively short transducer and two reflectors placed on both sides of it is also analyzed. This type of impedance element has smaller frequency shift between resonance and anti-resonance points. >