SiGe bipolar transceiver circuits operating at 60 GHz

A low-noise amplifier, direct-conversion quadrature mixer, power amplifier, and voltage-controlled oscillators have been implemented in a 0.12-/spl mu/m, 200-GHz f/sub T/290-GHz f/sub MAX/ SiGe bipolar technology for operation at 60 GHz. At 61.5 GHz, the two-stage LNA achieves 4.5-dB NF, 15-dB gain, consuming 6 mA from 1.8 V. This is the first known demonstration of a silicon LNA at V-band. The downconverter consists of a preamplifier, I/Q double-balanced mixers, a frequency tripler, and a quadrature generator, and is again the first known demonstration of silicon active mixers at V-band. At 60 GHz, the downconverter gain is 18.6 dB and the NF is 13.3 dB, and the circuit consumes 55 mA from 2.7 V, while the output buffers consume an additional 52 mA. The balanced class-AB PA provides 10.8-dB gain, +11.2-dBm 1-dB compression point, 4.3% maximum PAE, and 16-dBm saturated output power. Finally, fully differential Colpitts VCOs have been implemented at 22 and 67 GHz. The 67-GHz VCO has a phase noise better than -98 dBc/Hz at 1-MHz offset, and provides a 3.1% tuning range for 8-mA current consumption from a 3-V supply.     

Simulation and Optimization of Regular Motions of a Tube-Crawling Robot

The paper is devoted to issues associated with thetube-crawling robot designed at the Munich Technical University. Wefocus on the simulation of the robot dynamics and the optimization ofstructural parameters of the machine and characteristics of its gait.The mathematical model of the eight-legged tube-crawling robotperforming regular motions at a constant speed along a cylindrical tubeis described. On the basis of this model we investigate the influence ofthe machine design and gait parameters on the robot velocity and findtheir optimal values providing the maximal velocity under givenparametric and drive constraints. Numerical examples are presented anddiscussed.     

Identification and mapping of the gene encoding the glycoprotein complex gp82-gp105 of human herpesvirus 6 and mapping of the neutralizing epitope recognized by monoclonal antibodies

Monoclonal antibodies (MAbs) 2D4, 2D6, and 13D6 against human herpesvirus 6 (HHV-6) variant A strain GS recognized virion envelope glycoprotein complex gp82-gp105 and neutralized the infectivity of HHV-6 variant A group isolates. A 624-bp genomic fragment (82G) was identified from an HHV-6 strain GS genomic library constructed in the lambda gt11 expression system by immunoscreening with MAb 2D6. Rabbit antibodies against the fusion protein expressed from the genomic insert recognized glycoprotein complex gp82-gp105 from HHV-6-infected cells, thus confirming that the genomic fragment is a portion of the gene(s) that encodes gp82-gp105. This genomic insert hybridized specifically with viral DNAs from HHV-6 variant A strains GS and U1101 under high-stringency conditions but hybridized with HHV-6 variant B strain Z-29 DNA only under low-stringency conditions. DNA sequence analysis of the insert revealed a 167-amino-acid single open reading frame with an open 5' end and a stop codon at the 3' end. Hybridization studies with HHV-6A strain U1102 DNA localized the gp82-gp105-encoding gene to the unique long region near the direct repeat at the right end of the genome. To locate the neutralizing epitope(s) recognized by the MAbs, a series of deletions from the 3' end of the gene were constructed with exonuclease III, and fusion proteins from deletion constructs were tested for reactivity with MAbs in a Western immunoblot assay. Sequencing of deletion constructs at the reactive-nonreactive transition point localized the epitope recognized by the three neutralizing MAbs within or near a repeat amino acid sequence (NIYFNIY) of the putative protein. This repeat sequence region is surrounded on either side by two potential N-glycosylation sites and three cysteine residues.     

Aromatic hydroxylation is a major metabolic pathway of the mycotoxin zearalenone in vitro

Zearalenone (ZEN) is a common mycotoxin, for which only reductive metabolites have been identified so far. We now report that ZEN is extensively monohydroxylated by microsomes from human liver in vitro. Two of the major oxidative metabolites arise through aromatic hydroxylation and are catechols. Their chemical structures have been unambiguously determined by using deuterium‐labeled ZEN and by comparison with authentic reference compounds. Moreover, both catechol metabolites of ZEN were substrates of the enzyme catechol‐O‐methyl transferase. One of the monomethyl ethers represented the major metabolite when ZEN was incubated with rat liver slices, thus demonstrating that catechol formation also takes place under in vivo‐like conditions. Out of ten major human cytochrome P450 (hCYP) isoforms only hCYP1A2 was able to hydroxylate ZEN to its catechols with high activity. Catechol formation represents a novel pathway in the metabolism of ZEN and may be of toxicological relevance.     

Synthesis of the antioxidant glutathione in neurons: supply by astrocytes of CysGly as precursor for neuronal glutathione

Deficiency of the antioxidant glutathione in brain appears to be connected with several diseases characterized by neuronal loss. To study neuronal glutathione metabolism and metabolic interactions between neurons and astrocytes in this respect, neuron-rich primary cultures and transient cocultures of neurons and astroglial cells were used. Coincubation of neurons with astroglial cells resulted within 24 hr of incubation in a neuronal glutathione content twice that of neurons incubated in the absence of astroglial cells. In cultured neurons, the availability of cysteine limited the cellular level of glutathione. During a 4 hr incubation in a minimal medium lacking all amino acids except cysteine, the amount of neuronal glutathione was doubled. Besides cysteine, also the dipeptides CysGly and gammaGluCys were able to serve as glutathione precursors and caused a concentration-dependent increase in glutathione content. Concentrations giving half-maximal effects were 5, 5, and 200 microM for cysteine, CysGly, and gammaGluCys, respectively. In the transient cocultures, the astroglia-mediated increase in neuronal glutathione was suppressed by acivicin, an inhibitor of the astroglial ectoenzyme gamma-glutamyl transpeptidase, which generates CysGly from glutathione. These data suggest the following metabolic interaction in glutathione metabolism of brain cells: the ectoenzyme gamma-glutamyl transpeptidase uses as substrate the glutathione released by astrocytes to generate the dipeptide CysGly that is subsequently used by neurons as precursor for glutathione synthesis.     

HPLC quantification of major active components from 11 different saffron (Crocus sativus L.) sources

Eleven certified saffron samples (Crocus sativus L.), one each from Azerbaijan, China, Greece, France, India, Iran, Italy, New Zealand, Spain, Turkey and the Sigma Chemical Company, were analyzed by using an HPLC photodiode array detection method. This analysis quantified the 10 major saffron compounds in each sample and their concentration was analyzed at three different wavelengths. Results indicated that the Greek, Indian, New Zealand, and Spanish saffron extracts possessed the highest concentrations of water-soluble glycosidic carotenoids (?8.0%) suggesting that they could be a good source of this type of metabolites for further biological evaluation.     

Die Haseltalbrücke bei Suhl – Ausführungsplanung,Fertigung und Montage

The Haseltalbridge near Suhl – final design, fabrication and erection. The article describes the execution of the new Haseltal bridge near Suhl/Germany through the phases of final design, fabrication and erection under consideration of the complex local requirements.     

Glucuronidation of curcuminoids by human microsomal and recombinant UDP-glucuronosyltransferases

Glucuronidation is an important pathway in the metabolism of curcumin, but the isoforms of uridine-5'-diphosphoglucuronosyltransferase (UGT) involved are not known. Here, we report on the glucuronidation of the three natural curcuminoids and their major phase I metabolites with microsomes from human liver and intestine as well as with human recombinant UGTs. Microsomes from human liver generated predominantly the phenolic and small amounts of the alcoholic glucuronide of each curcuminoid, whereas intestinal microsomes formed only the phenolic conjugates but with higher activities. The phenolic glucuronidation of the curcuminoids was predominantly catalyzed by hepatic UGT1A1 and intestinal UGT1A8 and 1A10, whereas UGT1A9, 2B7, and 1A8 exhibited high activities for hexahydro-curcuminoids. UGT1A9 was able to form the alcoholic glucuronide of each curcuminoid in addition to the phenolic conjugate. These data suggest that the gastrointestinal tract contributes substantially to the glucuronidation of curcuminoids in humans, which may have important implications for their pharmacokinetic fate in vivo.