A New Hand-Held Microsystem Architecture for Biological Analysis

This paper presents a hand-held microsystem based on new fully integrated magnetoresistive biochips for biomolecular recognition (DNA hybridization, antibody antigen interaction, etc.). Magnetoresistive chip surfaces are chemically treated, enabling the immobilization of probe biomolecules such as DNA or antibodies. Fluid handling is also integrated in the biochip. The proposed microsystem not only integrates the biochip, which is an array of 16times16 magnetoresistive sensors, but it also provides all the electronic circuitry for addressing and reading out each transducer. The proposed architecture and circuits were specifically designed for achieving a compact, programmable and portable microsystem. The microsystem also integrates a hand-held analyzer connected through a wireless channel. A prototype of the system was already developed and detection of magnetic nanoparticles was obtained. This indicates that the system may be used for magnetic label based bioassays     

Solutions to a combined problem of excessive hydrogen sulfide in biogas and struvite scaling.

The Woodman Point Wastewater Treatment Plant (WWTP) in Western Australia has experienced two separate problems causing avoidable maintenance costs: the build-up of massive struvite (MgNH4PO4. 6H2O) scaling downstream of the anaerobic digester and the formation of hydrogen sulfide (H2S) levels in the digester gas to levels that compromised gas engine operation and caused high operating costs on the gas scrubber. As both problems hang together with a chemical imbalance in the anaerobic digester, we decided to investigate whether both problems could be (feasibly and economically) addressed by a common solution (such as dosing of iron solutions to precipitate both sulfide and phosphate), or by using separate approaches. Laboratory results showed that, the hydrogen sulfide emission in digesters could be effectively and economically controlled by the addition of iron dosing. Slightly higher than the theoretical value of 1.5 mol of FeCl3 was required to precipitate 1 mol of dissolved sulfide inside the digester. Due to the high concentration of PO4(3-) in the digested sludge liquor, significantly higher iron is required for struvite precipitation. Iron dosing did not appear an economic solution for struvite control via iron phosphate formation. By taking advantage of the natural tendency of struvite formation in the digester liquid, it is possible to reduce the risk of struvite precipitation in and around the sludge-dewatering centrifuge by increasing the pH to precipitate struvite out before passing through the centrifuge. However, as the Mg2+/PO4(3-) molar ratio in digested sludge was low, by increasing the pH alone (using NaOH) the precipitation of PO4(3-) was limited by the amount of cations (Ca2+ and Mg2+) available in the sludge. Although this would reduce struvite precipitation in the centrifuge, it could not significantly reduce PO4(3-) recycling back to the plant. For long-term operation, maximum PO4(3-) reduction should be the ultimate aim to minimise PO4(3-) accumulation in the plant. Magnesium hydroxide liquid (MHL) was found to be the most cost-effective chemical to achieve this goal. It enhanced struvite precipitation from both, digested sludge and centrate to the point where more than 95% PO4(3-) reduction in the digested sludge was achieved.     

Apoptosis and delayed neuronal damage after carbon monoxide poisoning in the rat

Delayed neurological damage after CO hypoxia was studied in rats to determine whether programmed cell death (PCD), in addition to necrosis, is involved in neuronal death. In rats exposed to either air or CO (2500 ppm), microdialysis in brain cortex and hippocampus was performed to determine the extent of glutamate release and hydroxyl radical generation during the exposures. Groups of control and CO-exposed rats also were tested in a radial maze to assess the effects of the CO exposures on learning and memory. At 3, 7, and 21 days after CO exposure brains were perfusion-fixed and hematoxylin-eosin (H&E) was used to assess injury and to select regions for further examination. DNA fragmentation was sought by examining cryosections with the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL) reaction. We found significant increases in glutamate release and .OH generation during and immediately after CO hypoxia. CO-exposed rats showed learning and memory deficits after exposure associated with heterogeneous cell loss in cortex, globus pallidus, and cerebellum. The frontal cortex was affected most seriously; the damage was slight at Day 3, increased at Day 7, and persistent at Day 21 after CO exposure. TUNEL staining was positive at all three time points, and TUNEL-labeled cells were distributed similarly to eosinophilic cells. The number of cells stained by TUNEL was less than by H&E and amounted to 2 to 5% of all cell nuclei in regions of injury. Ultrastructural features of both neuronal necrosis and apoptosis also were observed readily by electron microscopy. These findings indicate that both necrosis and apoptosis (PCD) contribute to CO poisoning-induced brain cell death.     

Study of the nozzle flow in a cross-flow turbine

An investigation of the flow inside the nozzle of a Cross-Flow turbine, which is a hydraulic turbine where the rectangular water jet issuing from the nozzle crosses the rotor blades twice, is presented here. Part of the investigation consisted in the experimental measurement of the static pressure distribution on the inside walls of two different nozzle configurations, both with the nozzle mounted alone and in the presence of a rotor. The tests performed in the presence of a rotor included the measurement of efficiency and covered a wide range of working conditions around the best efficiency point. The analysis of the results obtained in this way give us an indication of the influence of the turbine non-dimensional volume flow rate on the flow inside the nozzle and the way it affects the reaction degree of the machine and its efficiency level. Although most of the tests were carried out with a 25-blade rotor, one of the analysed nozzle configurations (that with an inside vane) was also tested with a 10-blade rotor, permitting the assessment of the effect the number of blades has on the flow in the nozzle.The flow inside the nozzle with no inside vane was numerically analysed using a method based on a Schwarz-Christoffel conformal transformation of variables. The numerical results show a fair agreement with the experimental data collected when the rotor was not present. A qualitative discussion of some of the losses occurring in the nozzle is advanced based on the computer results, and its conclusions are used for explaining the poor performance of the nozzle with no inside vane.     

1.04 GBd low EMI digital video interface system using small swingserial link technique

In a high-resolution flat panel system, a conventional interface that directly connects a liquid crystal display (LCD) controller to a flat panel cannot overcome the problems of excess EMI (electromagnetic interference) and power caused by full-swing transmission signals in parallel lines. This paper presents a high-speed digital video interface system implemented with a low-cost standard CMOS (complimentary metal-oxide-semiconductor) technology that can mitigate EMI and power problems in high-resolution flat panel display systems. The combined architecture of the high-speed, small number of parallel lines and low-voltage swing serial interface can support resolutions from VGA (640×480 pixels) up to XGA (1024×768 pixels) with significant power improvement and drastic EMI reduction. To support high-speed, low-voltage swing signaling and overcome channel-to-channel skew problems, a robust data recovery system is required. The proposed digital phase-locked loop enables robust skew-insensitive data recovery of up to 1.04 GBd     

Experimental peri-implant tissue breakdown around hydroxyapatite-coated implants

Factor V Leiden mutation was initially detected in thrombophilic patients and relatives by PCR RFLP (Restriction Fragment Length Polymorphism) according to Bertina (1). This technique presents some drawbacks and the current trend is to simplify the diagnosis. We describe a technique of Allele Specific Amplification (ASA) which is optimized in terms of reliability: an additional mismatch in antepenultimate position enables to obtain the same specificity as PCR RFLP. Furthermore, coamplification of internal control warrants an optimal sensitivity. All the PCR have been simplified: the DNA extraction improvement allows to analyse the genotype with only a few microliters of whole blood whatever the anticoagulant and the procedure of preservation (freezing, dried blood spots, storage at +4 degrees C for several days). This technique saves time. Moreover, full automation of the ASA technique may be shortened thanks to the lack of extraction and the positive/negative reading of the PCR signal.     

In vitro cytotoxicity and DNA damage production in Chinese hamster ovary cells and topoisomerase II inhibition by 2-[2''-(dimethylamino)ethyl]-1, 2-dihydro-3H-dibenz[de,h]isoquinoline-1,3-diones with substitutions at the 6 and 7 positions (azonafides)

The p53 tumor suppressor gene encodes a phosphoprotein which when overexpressed can induce growth arrest at the G1 and G2/M phases of the cell cycle, promote differentiation and apoptosis. This paper demonstrates that p53 can associate with trk tyrosine kinase. Expression of a murine temperature-sensitive (ts) p53 mutant in PC12 cells overexpressing trk (a model system to analyse cellular differentiation and signal transduction induced by NGF) induces morphological changes in the absence of NGF stimulation at 32 degrees C but not at 37 degrees C. In cells differentiated by p53, trk, but not EGFr, was hyperphosphorylated on tyrosine. Furthermore trk was not phosphorylated when expressed in Saos-2 cells (human osteosarcoma cells that lack expression of both endogenous trk and p53) at either temperature. However, transfection of ts p53 into these cells induces trk phosphorylation at 32 degrees C in the absence of NGF stimulation. Association of trk and p53 can be detected in NIH3T3 and PC12 cells co-expressing trk and the ts p53 mutant, in NIH3T3 and PC12 cells transfected with trk alone, and in untransfected PC12 cells, showing that overexpressed and/or endogenous trk associates with endogenous, low levels of p53. These data suggest a novel function for p53 which involves the stimulation of signal transduction pathways (mediating morphological properties of cells), possibly through association with and hyperphosphorylation of trk.