Flexural behaviour of precast segmental concrete beams internally prestressed with unbonded CFRP tendons under four-point loading

This study investigates the use of carbon fibre reinforced polymer (CFRP) tendons on precast segmental beams (PSBs) to tackle the corrosion problems which are likely to occur at joint locations of PSBs prestressed with steel tendons. Up to date, the use of CFRP tendons was extensively documented for monolithic beams while their application on PSBs has not been reported yet. Three precast segmental T-section beams including two beams with unbonded CFRP and one with steel tendons were built and tested under four-point loads in this study. The test results showed that CFRP tendons can be well used to replace the steel tendons on PSBs. The beams with CFRP tendons demonstrated both high strength and high ductility as compared to the beam with steel tendons. However, the stresses in the unbonded CFRP tendons at ultimate loading conditions of the tested beams were low, ranging from only about 66% to 72% of the nominal breaking tensile strength. The type of joints i.e. dry and epoxied, greatly affects the initial stiffness of the beams but has no effect on the opening of joints at ultimate loading stage. Moreover, a comprehensive examination on four existing code equations to predict the stress in the unbonded tendons showed that the four examined codes predicted well the stress at the ultimate loading condition of the unbonded steel tendons, however, they significantly under predicted those in the CFRP tendons. A modification in the strain reduction coefficient used by ACI 440.4R for predicting the stress increment in unbonded CFRP tendons of monolithic beams is therefore proposed for PSBs based on the experimental results

Building sustainability through water company and community linkages

The Three Delta Towns Water Supply and Sanitation Project is a joint venture between the governments of Vietnam and Australia to improve the welfare and living conditions for residents in the Mekong Delta towns of Bac Lieu, Ha Tien and Sa Dec. The project’s major focus is the development of urban environmental infrastructure, and also includes significant components of institutional strengthening and community development. A key implementation strategy for building the long term sustainability of the new infrastructure is to promote and strengthen linkages between the water and sanitation companies responsible for the infrastructure, and the communities they serve. Major challenges have been a lack of understanding by the companies as to the value of the community programs, and a significant lack of capacity at the town and community levels for initiating the various community programs. Now 2½ years into this 6 year project, the strategy is beginning to show results

Generation and Characterization of a genetic zebrafish model of SMA carrying the human SMN2 gene

<p>Abstract</p> <p>Background</p> <p>Animal models of human diseases are essential as they allow analysis of the disease process at the cellular level and can advance therapeutics by serving as a tool for drug screening and target validation. Here we report the development of a complete genetic model of spinal muscular atrophy (SMA) in the vertebrate zebrafish to complement existing zebrafish, mouse, and invertebrate models and show its utility for testing compounds that alter <it>SMN2 </it>splicing.</p> <p>Results</p> <p>The human motoneuron disease SMA is caused by low levels, as opposed to a complete absence, of the survival motor neuron protein (SMN). To generate a true model of SMA in zebrafish, we have generated a transgenic zebrafish expressing the human <it>SMN2 </it>gene (<it>hSMN2</it>), which produces only a low amount of full-length SMN, and crossed this onto the <it>smn</it>^-/-background. We show that human <it>SMN2 </it>is spliced in zebrafish as it is in humans and makes low levels of SMN protein. Moreover, we show that an antisense oligonucleotide that enhances correct <it>hSMN2 </it>splicing increases full-length <it>hSMN </it>RNA in this model. When we placed this transgene on the <it>smn </it>mutant background it rescued the neuromuscular presynaptic SV2 defect that occurs in <it>smn </it>mutants and increased their survival.</p> <p>Conclusions</p> <p>We have generated a transgenic fish carrying the human <it>hSMN2 </it>gene. This gene is spliced in fish as it is in humans and mice suggesting a conserved splicing mechanism in these vertebrates. Moreover, antisense targeting of an intronic splicing silencer site increased the amount of full length SMN generated from this transgene. Having this transgene on the <it>smn </it>mutant fish rescued the presynaptic defect and increased survival. This model of zebrafish SMA has all of the components of human SMA and can thus be used to understand motoneuron dysfunction in SMA, can be used as an vivo test for drugs or antisense approaches that increase full-length SMN, and can be developed for drug screening.</p

Absence of gemin5 from SMN complexes in nuclear Cajal bodies

<p>Abstract</p> <p>Background</p> <p>Spinal muscular atrophy is caused by reduced levels of the survival of motor neurons (SMN) protein. SMN is found in large complexes with Sm proteins and at least eight other proteins, including seven "gemins". These complexes are involved in the assembly of snRNPs in the cytoplasm and their transport into the nucleus, but the precise roles of the individual protein components are largely unknown.</p> <p>Results</p> <p>We have investigated the subcellular distribution of gemins using novel antibodies against gemins 3–7, and existing mAbs against SMN, gemin2, unrip, fibrillarin and profilin II. Most gemins were equally distributed between nuclear and cytoplasmic fractions of HeLa cells, but gemin5 and unrip were more abundant in the cytoplasm. In a cytoplasmic extract obtained by mild disruption of HeLa cells, nearly all the SMN and gemins 2–4 were in large complexes, but most of the gemin5 sedimented separately with a lower S value. Most of the unrip sedimented with gemins 6 and 7 near the top of the sucrose density gradients, separate from both SMN and gemin5. Anti-SMN mAbs pulled down gemin5 from cytoplasmic extracts, but not from nuclear extracts, and gemin5 did not co-sediment with large SMN complexes in nuclear extracts. These data suggest that gemin5 is easily detached from SMN-gemin complexes in the nucleus. By immuno-histochemistry, gemin5 was rarely detectable in nuclear gems/Cajal bodies, although it was accessible to antibody and easily detectable when present. This suggests that gemin5 is normally absent from SMN complexes in these nuclear storage sites.</p> <p>Conclusion</p> <p>We conclude that SMN complexes usually exist without gemin5 in nuclear gems/Cajal bodies. Gemin5 is believed to be involved in capturing snRNA into SMN complexes in the cytoplasm for transport into the nucleus. We hypothesize that gemin5, though present in the nucleus, is no longer needed for SMN complex function during the time these complexes are stored in gems/Cajal bodies.</p

Universality in odd-even harmonic generation and application in terahertz waveform sampling

Odd-even harmonics emitted from a laser-target system imprint rich, subtle information characterizing the system's dynamical asymmetry, which is desirable to decipher. In this Letter, we discover a simple universal relation between the odd-even harmonics and the asymmetry of the THz-assisted laser-atomic system -- atoms in a fundamental mid-IR laser pulse combined with a THz laser. First, we demonstrate numerically and then analytically formulize the harmonic even-to-odd ratio as a function of the THz electric field, the source of the system's asymmetry. Notably, we suggest a scaling that makes the obtained rule universal, independent of the parameters of both the fundamental pulse and atomic target. This universality facilitates us to propose a general pump-probe scheme for THz waveform sampling from the even-to-odd ratio, measurable within a conventional compact setup

Experiences from a rural water supply and sanitation programme, Vietnam

Experiences from a rural water supply and sanitation programme, Vietna

Visible light-induced switching of soft matter materials properties based on thioindigo photoswitches

Thioindigos are visible light responsive photoswitches with excellent spatial control over the conformational change between their trans- and cis- isomers. However, they possess limited solubility in all conventional organic solvents and polymers, hindering their application in soft matter materials. Herein, we introduce a strategy for the covalent insertion of thioindigo units into polymer main chains, enabling thioindigos to function within crosslinked polymeric hydrogels. We overcome their solubility issue by developing a thioindigo bismethacrylate linker able to undergo radical initiated thiol-ene reaction for step-growth polymerization, generating indigo-containing polymers. The optimal wavelength for the reversible trans-/cis- isomerisation of thioindigo was elucidated by constructing a detailed photochemical action plot of their switching efficiencies at a wide range of monochromatic wavelengths. Critically, indigo-containing polymers display significant photoswitching of the materials’ optical and physical properties in organic solvents and water. Furthermore, the photoswitching of thioindigo within crosslinked structures enables visible light induced modulation of the hydrogel stiffness. Both the thioindigo-containing hydrogels and photoswitching processes are non-toxic to cells, thus offering opportunities for advanced applications in soft matter materials and biology-related research

Impurity Effect on the In-plane Penetration Depth of the Organic Superconductors κ\kappa-(BEDT-TTF)2X_2X (XX = Cu(NCS)2_2 and Cu[N(CN)2_2]Br)

We report the in-plane penetration depth $\lambda_{\parallel}$ of single crystals $\kappa$-(BEDT-TTF)$_2X$ ($X=$ Cu(NCS)$_2$ and Cu[N(CN)$_2$]Br) by means of the reversible magnetization measurements under the control of cooling-rate. In $X$ = Cu(NCS)$_2$, $\lambda_{\parallel}(0)$ as an extrapolation toward $T$ = 0 K does not change by the cooling-rate within the experimental accuracy, while $T_{\textrm{c}}$ is slightly reduced. On the other hand, in $X$ = Cu[N(CN)$_2$]Br, $\lambda_{\parallel}(0)$ indicates a distinct increase by cooling faster. The different behavior of $\lambda_{\parallel}(0)$ on cooling-rate between the two salts is quantitatively explained in terms of the local-clean approximation (London model), considering that the former salt belongs to the very clean system and the later the moderate clean one. The good agreement with this model demonstrates that disorders of ethylene-group in BEDT-TTF introduced by cooling faster increase the electron(quasiparticle)-scattering, resulting in shorter mean free path.Comment: 8 pages, 9 figure

The XMM-Newton Wide-Field Survey in the COSMOS field (XMM-COSMOS): demography and multiwavelength properties of obscured and unobscured luminous AGN

We report the final optical identifications of the medium-depth (~60 ksec), contiguous (2 deg^2) XMM-Newton survey of the COSMOS field. XMM-Newton has detected ~800 X-ray sources down to limiting fluxes of ~5x10^{-16}, ~3x10^{-15}, and ~7x10^{-15} erg/cm2/s in the 0.5-2 keV, 2-10 keV and 5-10 keV bands, respectively. The work is complemented by an extensive collection of multi-wavelength data from 24 micron to UV, available from the COSMOS survey, for each of the X-ray sources, including spectroscopic redshifts for ~50% of the sample, and high-quality photometric redshifts for the rest. The XMM and multiwavelength flux limits are well matched: 1760 (98%) of the X-ray sources have optical counterparts, 1711 (~95%) have IRAC counterparts, and 1394 (~78%) have MIPS 24micron detections. Thanks to the redshift completeness (almost 100%) we were able to constrain the high-luminosity tail of the X-ray luminosity function confirming that the peak of the number density of logL_X>44.5 AGN is at z~2. Spectroscopically-identified obscured and unobscured AGN, as well as normal and starforming galaxies, present well-defined optical and infrared properties. We devised a robust method to identify a sample of ~150 high redshift (z>1), obscured AGN candidates for which optical spectroscopy is not available. We were able to determine that the fraction of the obscured AGN population at the highest (L_X>10^{44} erg s^{-1}) X-ray luminosity is ~15-30% when selection effects are taken into account, providing an important observational constraint for X-ray background synthesis. We studied in detail the optical spectrum and the overall spectral energy distribution of a prototypical Type 2 QSO, caught in a stage transitioning from being starburst dominated to AGN dominated, which was possible to isolate only thanks to the combination of X-ray and infrared observations.Comment: ApJ, in press. 59 pages, 14 figures, 2 Tables. A few typos corrected and a reference added. Table 2 is also available at http://www.mpe.mpg.de/XMMCosmos/xmm53_release ; a version of the paper in ApJ format (27 pages) is available at http://www.mpe.mpg.de/XMMCosmos/xmm53_release/brusa_xmmcosmos_optid.pd