Novel intramolecular reductive C-C coupling during borohydride reduction of a bi-enone

Borohydride reduction of the bi-enone (1) gave the structurally and mechanistically interesting compounds (4) and (5a-c) resulting from intramolecular carbon-carbon coupling.

On a generalized dynamic model of bi-state social interaction processes

A non-linear model, construed as a generalized version of the models put forth earlier for the study of bi-state social interaction processes, is proposed in this study. The feasibility of deriving the dynamics of such processes is demonstrated by establishing equivalence between the non-linear model and a higher order linear model.

Electrical transport in Bi doped n-type amorphous semiconductors (GeSe3.5)100-xBix at high pressure

Electrical transport in Bi doped amorphous semiconductors (GeSe3.5)100-xBix (x=0,4,10) is studied in a Bridgman anvil system up to a pressure of 90 kbar and down to 77 K. A pressure induced continuous transition from an amorphous semiconductor to a metal-like solid is observed in GeSe3.5. The addition of Bi disturbs significantly the behaviour of resistivity with pressure. The results are discussed in the light of molecular cluster model for GeySe1-y proposed by Phillips.

An analytical approach to the study of a class of bi-state social interaction processes

Sufficient conditions for obtaining an equivalent linear model to classes of non-linear, bi-state, social interaction processes are derived. These parametric constraints, when satisfied, permit analytical determination of the dynamics of the non-linear process of social interaction.

A noticeboard in "both worlds" unsurprising interfaces supporting easy bi-cultural content publication

We describe the design of a digital noticeboard to support communication within a remote Aboriginal community whose aspiration is to live in "both worlds", nurturing and extending their Aboriginal culture and actively participating in Western society and economy. Three bi-cultural aspects have emerged and are presented here: the need for a bi-lingual noticeboard to span both oral and written language traditions, the tension between perfunctory information exchange and social, embodied protocols of telling in person and the different ways in which time is represented in both cultures. The design approach, developed iteratively through consultation, demonstration and testing led to an "unsurprising interface", aimed at maximizing use and appropriation across cultures by unifying visual, text and spoken contents in both passive and interactive displays in a modeless manner.

Behaviour of Bi-material interface cracks in the presence of material nonlinearity of adherends

The well known features of crack face interpenetration/contact at the tip of an interface crack is re-examined using finite element analysis and assuming material nonlinear properties for the adherends. It was assumed in literature that the crack tips are fully open at all load levels in the presence of material nonlinearity of the adherends. Analysis for the case of remote tension shows that even in the presence of material nonlinearity, crack tip closes at small load levels and opens above a certain load level. Mixed-mode fracture parameters are evaluated for the situation when the crack tips are fully open. Due to the presence of nonlinearity, the mixed-mode fracture parameters are measured with the symmetric and anti-symmetric components of J-integral. The present analysis explains the sequence of events at the interface crack tip with progressively increasing remote tension load for the case of adherends with material nonlinear behaviour.

Bi-cultural content publication on a digital noticeboard: A design and cultural differences case study

We present our observations of Aboriginal Australian practices around a custom digital noticeboard and compare our insights to related research on cultural differences, literacy and ICT4D. The digital noticeboard was created, upon a request by the community Elders, to foster communication across the community. The initial design, informed by discussions and consultations, aimed at supporting the local Aboriginal language and English, both in written and spoken form, at supporting the oral tradition, and at accommodating for different perceptions and representations of time. This paper presents observations about the first encounters with the digital noticeboard by those members of the community that took part in its conceptualization. Such observations reinforce existing knowledge on such cultural phenomena as collectivism and time perception, issues related to literacy, moderation and censorship. We contribute to framing such knowledge within a concrete case study and draw implication for design of tools for bi-cultural content publication.

Evolution of nanocrystalline BaBi2Nb2O9 in Li2B4O7 BaO-Bi(2)O3-Nb2O5 glass system

Transparent glasses and glass nano crystal composites (GNCs) of various compositions in the system (100 - x)Li2B4O7-x (BaO-Bi2O3-Nb2O5) (where x = 10, 20, and 30 in molar ratio) were fabricated via splat-quenching technique. The glassy nature of the as quenched samples was established by differential thermal analyses. X-ray powder diffraction and transmission electron microscopic (TEM) studies confirmed the formation of layered perovskite BBN via a fluorite like phase. TEM studies revealed the presence of 10 nm sized spherical crystallites of fluorite like BaBi2Nb2O9 phase in the glassy matrix of Li2B4O7 (LBO). The influence of composition on the dielectric and the optical properties (transmission, optical band gap) of these samples has been investigated. (c) 2007 Elsevier B.V. All rights reserved.

Quadrature generation techniques for frequency multiplication based oscillators

Frequency multiplication (FM) can be used to design low power frequency synthesizers. This is achieved by running the VCO at a much reduced frequency, while employing a power efficient frequency multiplier, and also thereby eliminating the first few dividers. Quadrature signals can be generated by frequency- multiplying low frequency I/Q signals, however this also multiplies the quadrature error of these signals. Another way is generating additional edges from the low-frequency oscillator (LFO) and develop a quadrature FM. This makes the I-Q precision heavily dependent on process mismatches in the ring oscillator. In this paper we examine the use of fewer edges from LFO and a single stage polyphase filter to generate approximate quadrature signals, which is then followed by an injection-locked quadrature VCO to generate high- precision I/Q signals. Simulation comparisons with the existing approach shows that the proposed method offers very good phase accuracy of 0.5deg with only a modest increase in power dissipation for 2.4 GHz IEEE 802.15.4 standard using UMC 0.13 mum RFCMOS technology.

Data integration from two microarray platforms identifies bi-allelic genetic inactivation of RIC8A in a breast cancer cell line

Background: Using array comparative genomic hybridization (aCGH), a large number of deleted genomic regions have been identified in human cancers. However, subsequent efforts to identify target genes selected for inactivation in these regions have often been challenging. Methods: We integrated here genome-wide copy number data with gene expression data and non-sense mediated mRNA decay rates in breast cancer cell lines to prioritize gene candidates that are likely to be tumour suppressor genes inactivated by bi-allelic genetic events. The candidates were sequenced to identify potential mutations. Results: This integrated genomic approach led to the identification of RIC8A at 11p15 as a putative candidate target gene for the genomic deletion in the ZR-75-1 breast cancer cell line. We identified a truncating mutation in this cell line, leading to loss of expression and rapid decay of the transcript. We screened 127 breast cancers for RIC8A mutations, but did not find any pathogenic mutations. No promoter hypermethylation in these tumours was detected either. However, analysis of gene expression data from breast tumours identified a small group of aggressive tumours that displayed low levels of RIC8A transcripts. qRT-PCR analysis of 38 breast tumours showed a strong association between low RIC8A expression and the presence of TP53 mutations (P = 0.006). Conclusion: We demonstrate a data integration strategy leading to the identification of RIC8A as a gene undergoing a classical double-hit genetic inactivation in a breast cancer cell line, as well as in vivo evidence of loss of RIC8A expression in a subgroup of aggressive TP53 mutant breast cancers.

Behaviour of Bi-adhesive Joints

The use of relatively low modulus adhesive at the ends of overlap in a bi-adhesive bondline of a bonded joint can reduce the stress concentration significantly and, therefore, potentially lead to higher strength of the joint. This study presents the two-dimensional and three-dimensional nonlinear (geometric and material) finite element analyses of adhesively bonded single lap joints having modulus-graded bondline under monotonic loading conditions. The adhesives were modelled as an elasto-plastic multi-linear material, while the substrates were regarded as both linear elastic and bi-linear elasto-plastic material. The computational simulations have been performed to investigate the bondline behaviour by studying the stress and strain distributions both at the mid-plane as well as at the interface of the bondline. It has been observed that the static strength is higher for joints with bi-adhesive bondlines compared to those with single adhesives in bondline. Higher joint strength has also been observed for optimum bi-adhesive bondline ratio through parametric studies. Effects of load level, and bondline thickness on stress distribution in the bi-adhesive bondline have also been studied. 3D analysis results reveal the existence of complex multi-axial stress/strain state at the ends of the overlap in the bondline which cannot be observed in 2D plane strain analysis. About 1/3rd of the width of the joint from the free edge in the width direction has 3D stress state, especially in the compliant adhesive of the bondline. Magnitudes of longitudinal and lateral stress/strain components are comparable to peel stress/strain components. It has also been analytically shown that the in-plane global stiffness of the joint remains unaffected by modulus gradation of the bondline adhesive. (C) Koninklijke Brill NV, Leiden, 2010.

Dielectric properties of glasses prepared by quenching melts of superconducting Bi‐Ca‐Sr‐Cu‐O cuprates

Glasses obtained from quenching melts of superconducting bismuth cuprates of the formula Bi2(Ca,Sr)n+1CunO2n+4 with n=1 and 3 exhibit novel dielectric properties. They possess relatively high dielectric constants as well as high electrical conductivity. The novel dielectric properties of these cuprate glasses are likely to be of electronic origin. They exhibit a weak microwave absorption due to the presence of microcrystallites.

Neutron diffraction evidence for oxygen dimers in Bi-Ca-Sr-Cu-O superconductors

A comparative neutron diffraction study of Bi2CaSr2Cu2O8+δ, Bi2Ca2SrCu2O8+δ and Bi2Ca1.5Y0.5SrCu2O8+δ has not only shown the presence of considerable oxygen excess in the Bi layers, but also evidence for oxygen pairing giving rise to O1−2 or O2−2 type species, probably the latter. The proportion of the paired species increases when Y partly replaces Ca. Furthermore, the Tc decreases with an increase in paired species.