The Ge condensation technique: A solution for planar SOI/GeOI co-integration for advanced CMOS technologies?

This paper presents a general study on the germanium (Ge) condensation technique to assess its potential, issues and applications for advanced metal oxide semiconductor field effect transistor (MOSFET) technologies. The interest in such process for fabrication of ultrathin germanium on insulator (GeOI) layers for fully depleted GeOI MOSFETs application is first described. We highlight the impact of initial silicon on insulator (SOI) substrates uniformity on the process, determined as the key parameter to be improved. Next, a global procedure is described for MOSFETs integration on Ge layers grown on 75% Ge-enriched silicon germanium on insulator (SGOI) substrates obtained by the Ge condensation technique. A third section reviews the different local Ge condensation techniques for fabrication of SOI–GeOI hybrid substrates. Interests of such substrates for SOI–GeOI planar co-integration either at the microprocessor, at the cell or at the transistor level will be discussed. Finally, the fabrication of a first 50-nm-thick SOI–GeOI hybrid substrate is described.     

Birefringence in magneto-optical rib waveguides made by SiO2/TiO2 doped with γ-Fe2O3

Magneto-optic waveguides are the basic elements for nonreciprocal integrated optics; the phase matching between the fundamental TE and TM modes is an essential condition in magneto-optic waveguides. This condition can be satisfied with selected geometries planar or rib waveguides. We simulated the performance of such devices and determined the waveguide dimensions (height, width, and etching depth) that would allow the same propagation constants for both polarizations TE and TM.     

A Study of the NOx Selective Catalytic Reduction with Ethanol and Its By-products

The NOx selective catalytic reduction (SCR) with ethanol has been investigated over alumina supported silver catalyst with a special attention to the main involved reactions depending on the temperature test. With this aim, the possible reducers from ethanol transformations were also evaluated (C₂H₅OH, CH₃CHO, C₂H₄, CO). In addition, the contributions of the gas phase reactions and the alumina support were also pointed out. Based on the C-products and N-compounds distributions, it is assumed that at low temperature (T < 300 °C), ethanol reacts firstly with NO + O₂ to produce acetaldehyde and N₂. For higher temperatures, two reaction pathways have been proposed, supported by the CH₃CHO-SCR results: a direct reaction between NO₂ and CH₃CHO, or via –NCO species.     

Effect of natural organic matter on zinc inhibition of hematite bioreduction by Shewanella putrefaciens CN32

The effect of zinc on the biological reduction of hematite (alpha-Fe2O3) by the dissimilatory metal-reducing bacterium (DMRB) Shewanella putrefaciens CN32 was studied in the presence of four natural organic materials (NOMs). Experiments were performed under non-growth conditions with H2 as the electron donor and zinc inhibition was quantified as the decrease in the 5 d extent of hematite bioreduction as compared to no-zinc controls. Every NOM was shown to significantly increase zinc inhibition during hematite bioreduction. NOMs were shown to alter the distribution of both biogenic Fe(II) and Zn(II) between partitioned (hematite and cell surfaces) and solution phases. To further evaluate the mechanism(s) of NOM-promoted zinc inhibition, similar bioreduction experiments were conducted with nitrate as a soluble electron acceptor, and hematite bioreduction experiments were conducted with manganese which was essentially non-inhibitory in the absence of NOM. The results suggest that Me(II)-NOM complexes may be specifically inhibitory during solid-phase bioreduction via interference of DMRB attachment to hematite through the formation of ternary Me(II)-NOM-hematite complexes.     

A Thermostable Aldolase for the Synthesis of 3‐Deoxy‐2‐ulosonic Acids

A stereochemically promiscuous 2‐keto‐3‐deoxygluconate aldolase has been used as an efficient biocatalyst to catalyse the aldol reaction of pyruvate with C₃‐ and C₄‐aldoses to afford syn‐ and anti‐3‐deoxy‐2‐ulosonic acids in poor to good de. A continuous flow bioreactor containing immobilised aldolase has been developed that enables gram quantities of C₆‐ and C₇‐3‐deoxyhept‐2‐ulosonic acids to be produced in an efficient manner.     

A prospective, multicenter, randomized trial comparing steroids and pulse cyclophosphamide versus steroids and oral cyclophosphamide in the treatment of generalized Wegener's granulomatosis

OBJECTIVE: To investigate the effectiveness and side effects of oral versus pulse cyclophosphamide (CYC) in combination with corticosteroids (CS) in the treatment of systemic Wegener's granulomatosis (WG). METHODS: Patients with newly diagnosed systemic WG were enrolled in a prospective, randomized trial. At the time of diagnosis, prior to randomization, every patient received a daily injection of methylprednisolone for 3 days, followed by daily oral prednisone (1 mg/kg/day) and a 0.7-gm/m2 pulse of CYC. Patients were then randomly assigned to receive either prednisone plus intravenous pulse CYC (group A) or prednisone plus oral CYC (group B) as first-line treatment. CYC was given for at least 1 year and was then progressively tapered and discontinued. RESULTS: Fifty patients were included in the study: 27 in group A and 23 in group B. At 6 months, 24 group A patients (88.9%) were in remission, versus 18 group B patients (78.3%). At the end of the trial, 18 group A patients (66.7%) and 13 group B patients (56.5%) were in remission. In group A, 66.7% of the patients experienced side effects, versus 69.6% in group B. Infectious side effects were significantly more frequent in group B (69.6%) than in group A (40.7%) (P < 0.05). The incidence of Pneumocystis carinii pneumonia was higher in oral CYC-treated patients (30.4%) than in pulse CYC-treated patients (11.1%). Nine group A patients (33.3%) and 10 group B patients (43.5%) died. Actuarial curves showed that relapses were significantly more frequent in group A (59.2%) than in group B (13%) (P = 0.02). CONCLUSION: Our results indicate that pulse CYC is as effective as oral CYC in achieving initial remission of WG and is associated with fewer side effects and lower mortality. However, in the long term, treatment with pulse CYC does not maintain remission or prevent relapses as well as oral CYC.     

Hourly simulations of the microwave brightness temperature of seasonal snow in Quebec, Canada, using a coupled snow evolution-emission model

To interpret the snowpack evolution, and in particular to estimate snow water equivalent (SWE), passive microwave remote sensing has proved to be a useful tool given its sensitivity to snow properties. However, the main uncertainties using existing SWE algorithms arise from snow metamorphism which evolves during the winter season, and changes the snow emissivity. To consider the evolution in snow emissivity a coupled snow evolution-emission model can be used to simulate the brightness temperature (T_B) of the snowpack.During a dedicated campaign in the winter season, from November to April, of 2007-2008 two surface-based radiometers operating at 19 GHz and 37 GHz continuously measured the passive microwave radiation emitted through a seasonal snowpack in southern Quebec (Canada). This paper aims at modeling and interpreting this time series of T_B over the whole season, with an hourly step, using a coupled multi-layer snow evolution-emission model. The thermodynamic snow evolution model, referred as to Crocus, was driven by local meteorological measurements. Results from this model provided, in turn, the input variables to run the Microwave Emission Model of Layered Snowpacks (MEMLS) in order to predict T_B at 19 GHz and 37 GHz for both vertical (V) and horizontal (H) polarizations. The accuracy of T_B predicted by the Crocus-MEMLS coupled model was evaluated using continuous measurements from the surface-based radiometers.The weather conditions observed during the winter season were diverse, including several warm periods with melting snow and rain-on-snow events, producing very complex variations in the time series of T_B. To aid our analysis, we identified days with melting snow versus days with dry snow. The Crocus-MEMLS coupled model was able to accurately predict melt events with a success rate of 86%. The residual error was due to an overestimation of the duration of several melt events simulated by Crocus. This problem was explained by 1) a limitation of percolation, and 2) a very long-acting melt of lower layers due to geothermal flux.When the snowpack was completely dry, the global trend of T_B during the season was characterized by a decrease of T_B due to growth in the snow grain size. During most of the season, Crocus-MEMLS correctly predicted the evolution of T_B resulting from temperature gradient metamorphism; the root mean square errors ranged between 2.8 K for the 19 GHz vertical polarization (19V) and 6.9 K for the 37 GHz horizontal polarization (37H). However, during dry periods near the end of the season, the values of T_B were strongly overestimated. This overestimation was mainly due to a limitation of the growth of large snow grains in the wet snowpack simulated by Crocus. This effect was confirmed by estimating snow grain sizes from the observed T_B and the coupled model. The estimated snow grain sizes were larger and more realistic than those initially predicted by the Crocus model.