Liquidus Diagram of the Ba-Y-Cu-O System in the Vicinity of the Ba2YCu3O6+x Phase Field

This paper describes the melting equilibria in the vicinity of the high T_c phase Ba₂YCu₃O_6+x, including evidence for two Ba-Y-Cu-O immiscible liquids. Melting equilibria have been investigated in purified air using a combination of differential thermal analysis (DTA), thermogravimetric analysis (TGA), powder x-ray diffraction (XRD), MgO wick entrapment of liquid for analysis, scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDS), and hydrogen reduction for determination of copper oxidation state. For relatively barium-rich compositions, it was necessary to prepare the starting materials under controlled atmosphere conditions using BaO. A liquidus diagram was derived from quantitative data for the melts involved in various melting reactions. In general the 1/2(Y₂O₃) contents of the melts participating in these equilibria were low (mole fraction <4 %). The primary phase field of Ba₂YCu₃O_6+x occurs at a mole fraction of <2.0 % 1/2Y₂O₃ and lies very close along the BaO-CuO_x edge, extending from a mole fraction of ≈43 % CuO to a mole fraction of ≈76 % CuO. It is divided by a liquid miscibility gap and extends on either side about this gap. The topological sequence of melting reactions associated with the liquidus is presented as a function of temperature. Implications for the growth of Ba₂YCu₃O_6+x crystals are discussed.     

EPA and DHA Status of South Asian and White Canadians Living in the National Capital Region of Canada

To minimize the risk of cardiovascular disease (CVD), most dietary guidelines have recommended consuming 500 mg/day of eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA) or two servings of oily fish/week. The sum of percent EPA and DHA in red blood cell (RBC) total fatty acids-termed the omega-3 index-has been proposed as a biomarker for assessing the risk of death from CVD. The omega-3 indices of ≤4, >4 to <8 and ≥8 % have been proposed to be associated with high, intermediate and low CVD risks, respectively. In this study, we determined the EPA + DHA intake level and the omega-3 index of South Asian Canadians (SAC; n = 308) and white Canadians (WC; n = 341) age 20–79 years living in the National Capital Region of Canada. The mean EPA + DHA intake levels were 569 ± 571 mg/day for SAC and 684 ± 865 mg/day for WC and 46 % of SAC and 43 % of WC met the recommended EPA + DHA intake level of 500 mg/day. The mean omega-3 indices were 6.6 and 5.9 % for SAC and WC respectively. The suggested cardio-protective target level for the omega-3 index of ≥8 % was observed only in 19.8 % of SAC and in 9.4 % of WC subjects. The majority of the participants (74.4 % of SAC and 82.7 % of WC) were in the >4 to <8 % range. These results suggest that although study participants’ dietary intake of EPA + DHA is adequate, this intake was not sufficient to provide an omega-3 index that is considered cardio-protective.     

Integrated SWCNT sensors in micro-wind tunnel for air-flow shear-stress measurement

We have developed SWCNT sensors for air-flow shear-stress measurement inside a polymethylmethacrylate (PMMA) “micro-wind tunnel” chip. An array of sensors is fabricated by using dielectrophoretic (DEP) technique to manipulate bundled single-walled carbon nanotubes (SWCNTs) across the gold microelectrodes on a PMMA substrate. The sensors are then integrated in a PMMA micro-wind tunnel, which is fabricated by SU-8 molding/hot-embossing technique. Since the sensors detect air flow by thermal transfer principle, we have first examined the I–V characteristics of the sensors and confirmed that self-heating effect occurs when the input voltage is above ~1 V. We then performed the flow sensing experiment on the sensors using constant temperature (CT) configuration with input power of ~230 μW. The voltage output of the sensors increases with the increasing flow rate in the micro-wind tunnel and the detectable volumetric flow is in the order of 1 × 10⁻⁵m³/s. We also found that the activation power of the sensors has a linear relation with 1/3 exponential power of the shear stress which is similar to conventional hot-wire and polysilicon types of convection-based shear-stress sensors. Moreover, measurements of sensors with different overheat ratios were compared, and results showed that sensor is more sensitive to the flow with a higher overheat ratio.     

A 2-adic approach to the analysis of cyclic codes

This paper describes how 2-adic numbers can be used to analyze the structure of binary cyclic codes and of cyclic codes defined over Z _2(a), a⩾2, the ring of integers modulo 2^a. It provides a 2-adic proof of a theorem of McEliece that characterizes the possible Hamming weights that can appear in a binary cyclic code. A generalization of this theorem is derived that applies to cyclic codes over Z_2(a) that are obtained from binary cyclic codes by a sequence of Hensel lifts. This generalization characterizes the number of times a residue modulo 2^a appears as a component of an arbitrary codeword in the cyclic code. The limit of the sequence of Hensel lifts is a universal code defined over the 2-adic integers. This code was first introduced by Calderbank and Sloane (1995), and is the main subject of this paper. Binary cyclic codes and cyclic codes over Z_2(a) are obtained from these universal codes by reduction modulo some power of 2. A special case of particular interest is cyclic codes over Z₄ that are obtained from binary cyclic codes by means of a single Hensel lift. The binary images of such codes under the Gray isometry include the Kerdock, Preparata, and Delsart-Goethals codes. These are nonlinear binary codes that contain more codewords than any linear code presently known. Fundamental understanding of the composition of codewords in cyclic codes over Z₄ is central to the search for more families of optimal codes. This paper also constructs even unimodular lattices from the Hensel lift of extended binary cyclic codes that are self-dual with all Hamming weights divisible by 4. The Leech lattice arises in this way as do extremal lattices in dimensions 32 through 48     

Microfluidic bioreactors for culture of non-adherent cells

Microfluidic bioreactors (μBR) are becoming increasingly popular for cell culture, sample preparation and analysis in case of routine genetic and clinical diagnostics. We present a novel μBR for non-adherent cells designed to mimic in vivo perfusion of cells based on diffusion of media through a sandwiched membrane. The culture chamber and perfusion chamber are separated by a sandwiched membrane and each chamber has separate inlet/outlets for easy loading/unloading of cells and perfusion of the media. The perfusion of media and exchange of nutrients occur through the sandwiched membrane, which was also verified with simulations. Finally, we present the application of this device for cytogenetic sample preparation, whereby we culture and arrest peripheral T-lymphocytes in metaphase and later fix them in the μBR. The expansion of T-lymphocytes from an unknown patient sample was quantified by means of CFSE staining and subsequent counting in a flow cytometer. To conclude on the applicability of μBR for genetic diagnostics, we prepare chromosome spreads on glass slides from the cultured samples, which is the primary step for metaphase FISH analysis.     

酿酒亲兄弟——记勃艮第Canpitain Gagnerot葡萄酒酒庄

在法国的勃艮第地区,大多数酿酒人在表达他们对于土地、葡萄以及酿酒的热忱与执著的同时,常表现出各自鲜明的个性。这些个性有时甚至是排他的,即便是兄弟姐妹之间也常会各立门户,独立酿酒。然而,在勃艮第Capitain Gagnerot酒庄(Domaine Capitain Gagnerot),现任的主人——一对稳重谦和的兄弟,却让人感受到这对酿酒亲兄弟间的真情。同时,让人感动的还有那款款溶有两兄弟真诚的佳酿。