Validation of a Method of Determination of Apparent Diffusivity Versus Composition in Solids

A method is presented for computing the values of apparent diffusivity in solids with respect to the concentration of the diffusing substance (water or sodium chloride). This method does not require any assumption upon the mathematical relationship between diffusivity and concentration. It can be applied to experimental measurements of local concentration versus position within the solid (profiles) with relatively few measurements (circa 10) and a mathematical smoothing of the experimental data by using an artificial neural network model. The method was first validated on simulated data obtained by using a constant diffusivity value and on experimental profiles when the relation between diffusivity and concentration was given. It was then applied to original experimental moisture profiles obtained by putting gelatin gels with different initial moisture contents into contact for up to 14 days. The method was also successfully applied to five sets of experimental moisture and sodium chloride profiles taken from the literature and obtained from different food products. Apparent diffusivities calculated by our method were found in agreement with those obtained by authors using different numerical methods to compute the diffusivity values.     

Phosphorus Inputs to Lake Simcoe from 1990 to 2003: Declines in Tributary Loads and Observations on Lake Water Quality

Total phosphorus (TP) inputs to Lake Simcoe have led to hypolimnetic dissolved oxygen (DO) depletion and loss of cold water fish habitat. Since 1990, efforts have been made to reduce the total TP input to the lake below a defined target of 75 t/year, which was predicted to lead to reductions in spring TP concentration and improvements in end-of-summer hypolimnetic DO concentrations. The total TP load to the lake during the most recent period of record (1998/99-2003/04) ranged from 53 to 76 t/yr and averaged 67 t/yr, compared to an average of 114 t/yr estimated between 1990/91 and 1997/98 (range 85-157 t/yr). Reductions in TP loads from the catchment via tributary discharge (∼26 t) accounted for the majority of the decrease in total load between the two time periods. Total P concentrations decreased significantly in four out of six long-term monitored tributaries; however, concentrations in all six tributaries remain above the level recommended to avoid nuisance plant growth (30 μg/L). Although TP loads to the lake are currently below the target 75 t/yr, excessive growths of filamentous algae and macrophytes continue to be a problem in the nearshore zone. End-of-summer minimum hypolimnetic DO concentrations (average 4.3 mg/L, 1998/99-2003/04) remain substantially below the level (7 mg/L) that is considered protective of lake trout. Efforts to reduce TP loads to the lake therefore need to continue.     

Stable Oxygen and Carbon Isotopic Compositions of Lates stappersii Otoliths from Lake Tanganyika,East Africa

In this study, we measured growth trends in oxygen and carbon isotopic ratios in whole sagittal otoliths from three adult centropomid fish (Lates stappersii) from each of three sub-basins of Lake Tanganyika, East Africa. Sampling density was 20 to 50 samples per otolith. Both δ¹⁸O and δ¹³C values increase with age. The δ¹⁸O data suggest that otoliths were precipitated near the expected equilibrium with the ambient environment (ca. +3.5‰) and support a migration pattern from surface waters during larval stages to deeper waters (40 to 80 m) for mature fish. Relatively high δ¹⁸O values in the southern sub-basin are consistent with cooler temperatures in the region during seasonal upwelling. The δ13C increase from otolith core to edge is large (up to 4‰) and is interpreted as due to ontogenetic changes in diet and contributions from a decrease in the proportion of respired CO₂ incorporated into otolith carbonate as metabolic rates of the fish dropped with maturity. The data seem to successfully reveal life strategy and migration patterns of L. stappersii, document regional differences in lake conditions, and provide a record of temperature within the water column during which the fish lived. Higher resolution studies and analyses of historical samples could be used to constrain modern and past growth patterns, and to reconstruct past temperature gradients and productivity patterns in the lake.     

Associative properties of perfluorooctyl end‐functionalized polystyrene–poly(ethylene oxide) diblock copolymers

The synthesis of 2,2,3,3‐tetrahydro‐perfluoroundecanoyl end‐functionalized polystyrene–poly(ethylene oxide) block (PS‐block‐PEO‐R_F) copolymers and their matching PS‐block‐PEO diblock copolymers was carried out by sequential anionic polymerization. Viscometry and ¹⁹F NMR studies show that the PS‐block‐PEO copolymers, in contrast to their matching PS‐block‐PEO‐R_F copolymers, exhibit a micellar rather than the associative behavior seen for the latter. However, the presence of an excess of fluorinated acid, used for end‐functionalization, produces a reduction of the associative behavior above the overlap concentration, with the fluorinated acid acting like a surfactant. A competition may also occur between PS—and R_F—mediated micellization. Copyright © 2004 Society of Chemical Industry     

A full-wave analysis of interconnection planar lines applications to structures with finite ground plane

The high integration level associated to the increase of the operating frequency of microelectronic integrated circuits create complex electromagnetic coupling in the interconnection lines which lead to mismatch and frequency dispersion. In the present paper, we propose a full-wave analysis to characterise the electromagnetic behaviour of interconnection planar lines using mixed-potential integral equations technique. The theoretical and numerical treatments of Green’s functions for the specific structures are firstly presented. The calculated results for parallel and coplanar strips are compared to the published ones. The effect of the finite ground plane on the propagation constant and the characteristic impedance is then analysed for different permittivities. The obtained theoretical and experimental results for the reflection coefficient of straight resonators confirm finally the observed effect of the finite ground plane on the frequency dispersion and the scattering characteristics.     

A fully on-chip LDO voltage regulator with 37 dB PSRR at 1 MHz for remotely powered biomedical implants

This article presents a fully on-chip low-power LDO voltage regulator dedicated to remotely powered wireless cortical implants. This regulator is stable over the full range of alternating load current and provides fast load regulation achieved by applying a time-domain design methodology. Moreover, a new compensation technique is proposed and implemented to improve PSRR beyond the performance levels which can be obtained using the standard cascode compensation technique. Measurement results show that the regulator has a load regulation of 0.175 V/A, a line regulation of 0.024%, and a PSRR of 37 dB at 1 MHz power carrier frequency. The output of the regulator settles within 10-bit accuracy of the nominal voltage (1.8 V) within 1.6 μs, at full load transition. The total ground current including the bandgap reference circuit is 28 μA and the active chip area measures 290 μm × 360 μm in a 0.18 μm CMOS technology.     

Quantitative determination of Botrytis laccase in musts and wines by the syringaldazine test

The syringaldazine assay was adapted for quantitative determination of laccase (EC 1.10.3.2) activity from Botrytis cinerea Pers in musts and new wines. This colorimetric method is fast, specific and sensitive. It makes it possible to assess the level of contamination of crops by Botrytis cinerea. The assay can be performed in the presence of tyrosinase but the phenolic compounds of the grape must first be eliminated because of their inhibition of syringaldazine oxidation by laccase. When measured in botrytised grape, laccase activity is related to the stages of development of the fungus.     

Générateur de machines séquentielles autotestables pour circuits intégrés spécifiques

This paper presents an original method using a ROM memory, of systematically synthesizing on-line and offline self-testing synchronous sequential machines (automata, sequencers,), for the design of compiled ASIC’S. Choices about state transition graph coding and circuit architecture are related to simplicity, compactness, operating rate and especially to testability. The on-line and off-line testing is based on an error detecting code of a recurrent type: in addition to useful data, the ROM memory contains redundant information which is distributed between two consecutive states. This method guarantees both present state coherence and past transition conformity. On-line testing is based in this type of coding, called distributed redundancy coding. Its fault coverage is given for different classes of hardware failures. Off-line testing, which is exhaustive, uses the distributed redundancy coding technique and consists in scanning all the possible graph transitions in memory address order.     

Who profits from the Canadian nanotechnology reward system? Implications for gender-responsible innovation

Scientometrics - Gender equality is one of the primary dimensions of responsible research and innovation. Based on bibliometric and survey data of nanotechnology researchers in Canada, this paper...     

Top-down study of β2-microglobulin deamidation

Although differentiation of the isomeric Asn deamidation products (Asp and isoAsp) at the peptide level by electron capture dissociation (ECD) has been well-established, isoAsp identification at the intact protein level remains a challenging task. Here, a comprehensive top-down deamidation study is presented using the protein beta2-microglobulin (β(2)M) as the model system. Of the three deamidation sites identified in the aged β(2)M, isoAsp formation was detected at only one site by the top-down ECD analysis. The absence of diagnostic ions likely resulted from an increased number of competing fragmentation channels and a decreased likelihood of product ion separation in ECD of proteins. To overcome this difficulty, an MS(3) approach was applied where a protein ion was first fragmented by collisionally activated dissociation (CAD) and the resulting product ion was isolated and further analyzed by ECD. IsoAsp formation at all three deamidation sites was successfully identified by this CAD-ECD approach. Furthermore, the abundance of the isoAsp diagnostic ion was found to increase linearly with the extent of deamidation. These results demonstrated the potential of ECD in the detection and quantitative analysis of isoAsp formation using the top-down approach.