An integrated RF transceiver for DECT application

An integrated circuit (IC) is presented which implements the complete RF front-end solution for a digital enhanced cordless communications (DECT) cordless phone provided that a single-transistor LNA and a power amplifier are included on the application board. Focus has been put in the paper on the image rejection mixer which achieves image rejection mean values of 43 dB and on the fully integrated voltage-controlled oscillators which guarantees -134 dBc phase noise at 6.5-MHz offset over temperature and process variation. The circuit was fabricated in a high-performance low-cost 20-GHz silicon bipolar technology and assembled on a TQFP64 package. It was tested on the complete application board including the LNA and the power amplifier, and it fully complies with the ETSI TBR06 standard requirements. The internal power supply is 2.8 V     

THE ROLE OF CLAY MINERALS AND ALUMINA-TREATED CLAY MINERALS IN HYDROGENATION AND PYROLYSIS OF SOLVENT-REFINED COAL

The hydrogenatlon and pyrolysls behaviour of solvent-refined coal (SRC) and base-free SRC have been investigated in the presence and absence of clay minerals and alumina-modified clay minerals. The yields of chloroform-soluble and insoluble products (coke) and aromaticities of chloroform-insoluble products have been measured to elucidate the mechanisms of these processes. The yield of chloroform-soluble products was greater after pyrolysis under molecular hydrogen than under molecular nitrogen, even though there was no decrease in the aromaticity of the products in either case. Hence hydrogen can assist in the formation of chloroform-soluble products without aryl ring hydrogenation. Higher yields of chloroform-soluble products were obtained with base-free SRC than with SRC but little or no effect of mineral matter was observed. It is suggested that SRC bases play an important and direct role in promoting in situ coking reactions apart from their well-established role in blocking acidic cracking sites.     

The effects of anandamide on memory consolidation in mice involve both D1 and D2 dopamine receptors

Post-training administration of anandamide (1.5, 3, 6 mg/kg) dose-dependently impairs the retention of an inhibitory avoidance response in mice. The effects on retention performance induced by the drug appear to be due to an effect on memory consolidation, as they were observed when drugs were given at short, but not long, periods of time after training, i.e. when the memory trace was susceptible to modulation. Pretreatment with either selective D1 or D2 dopamine (DA) receptor agonists, SKF 38393 and quinpirole, at doses that were ineffective when given alone (5 and 0.25 mg/kg, respectively), antagonized the effects of anandamide on memory consolidation, suggesting that D1 and D2 receptors are similarly involved in the effects of anandamide on memory consolidation. These results are discussed in terms of a possible inverse relationship between the modulation of memory processes by endogenous cannabinoid and DA systems.     

Enuresis: causes, cures and cautions

Enuresis is a common benign condition that affects up to 10 percent of school children. Innumerable causes have been proposed: emotional disturbances, small bladders, infections, allergies, polyuria and deep sleep. In an effort to modify abnormal sleep, drugs such as amphetamine or imipramine are frequently prescribed. Imipramine is often very effective but its acute toxicity is not fully appreciated by many patients or their parents. Since accidental imipramine overdose is a serious matter, strict rules regarding its storage and use must be enforced.     

High-speed voltage buffers for the experimental characterization ofCMOS transconductance operational amplifiers

Two voltage buffers realized with discrete components are presented which provide very low input capacitance and input bias current, high-frequency capability and low-output resistance. This performance means they are well suited for employment in the characterization of operational amplifiers and specifically CMOS transconductance operational amplifiers     

An acetylcholinesterase/choline oxidase-based amperometric biosensors as a liquid chromatography detector for acetylcholine and choline determination in brain tissue homogenates

A liquid chromatography (LC) detector based on a fast response and sensitive bienzyme amperometric biosensor for acetylcholine (ACh) and choline (Ch) is described. The detector fabrication consisted of glutaraldehyde co-crosslinking of acetylcholinesterase and choline oxidase with bovine serum albumin on the Pt working electrode of a conventional thin-layer electrochemical flow cell. The influence of some experimental parameters (e.g., enzyme loading, thickness of the bienzyme layer, flow rate) on the detector characteristics has been studied in order to optimize the analyte response while minimizing band-broadening and distortion. A mobile phase consisting of a phosphate buffer (I, 0.1 M; pH, 6.5) containing 5 mM sodium hexane sulfonate and 10 mM tetramethylammonium phosphate was found to give very satisfactory resolution and peak shape in ion-pair, reversed-phase LC. Linear responses were observed over at least four decades and absolute detection limits (at a signal-to-noise ratio of 3) were 12 and 27 fmol injected for Ch and ACh, respectively. After one month of intensive use in the LC system, the detector retained about 70% of its initial sensitivity. The potential of the described approach is demonstrated by the simultaneous determination of Ch and ACh in rat brain tissue homogenates.     

Manipulation of Mesoscopic Phase Separation by X-ray Illumination

High resolution synchrotron X-ray diffraction is used to study the dynamics of oxygen ordering in a La₂CuO_4.08 single crystal as a function of the temperature and of the photon flux. We have observed the occurrence of a phase separation between disordered and 3D long-range ordered domains of interstitial oxygen atoms (the latter being commensurate with the lattice). We are able to study and control the phase separation by irradiating the sample while varying the temperature in a range between 350 K and 250 K. These results shed new light on the oxygen ordering in cuprates; in addition, we show that in such systems it is possible to manipulate and to control structural inhomogeneities at the atomic scale using X-ray diffraction. This work was supported by European project 517039 “Controlling Mesoscopic Phase Separation” (COMEPHS) (2005).     

The electrochemistry of carbon monoxide reductive cyclotetramerization to squarate anion

The electrochemical reduction, of carbon monoxide to C₄O^2?₄ squarate anion is investigated. Particular attention is devoted to the influence that solvents, electrolytes, electrodes and carbon monoxide pressure have on the yields.The main feature appears to be that strictly controlled conditions are not necessary for cyclotetramerization.In dmf — Bu₄NBr the following yields vs reacted CO and circulated charge were obtained with different cathodes: Pt(49%, 34%); Au(48%, 29%); Al(47%, 38%); stainless steel (36%, 33%); graphite (39%, 31%). A distinct influence of the supporting electrolyte (inorganic and tetraalkylammonium halides) was however observed.