Comparison of moment-curvature models for fiber-reinforced polymer plate-end debonding studies using global energy balance approach

This paper compares a number of different moment-curvature models for cracked concrete sections that contain both steel and external fiber-reinforced polymer (FRP) reinforcement. The question of whether to use a whole-section analysis or one that considers the FRP separately is discussed. Five existing and three new models are compared with test data for moment-curvature or load deflection behavior, and five models are compared with test results for plate-end debonding using a global energy balance approach (GEBA). A proposal is made for the use of one of the simplified models. The availability of a simplified model opens the way to the production of design aids so that the GEBA can be made available to practicing engineers through design guides and parametric studies. Copyright © 2014, American Concrete Institute.

Analysis and retrofitting design of a single-span R.C. bridge

This paper deals with the case history of a damaged one-span prestressed concrete bridge on a crucial artery near the city of Cagliari (Sardinia), along the sea-side. After being involved in a disastrous flood, attention has arisen on the worrying safety state of the deck, submitted to an intense daily traffic load. Evident signs of this severe condition were the deterioration of the beams concrete and the corrosion, the lack of tension and even the rupture of the prestressing cables. After performing a limited in situ test campaign, consisting of sclerometer, pull out and carbonation depth tests, a first evaluation of the safety of the structure was performed. After collecting the data of dynamic and static load tests as well, a comprehensive analysis have been carried out, also by means of a properly calibrated F.E. model. Finally the retrofitting design is presented, consisting of the reparation and thickening of the concrete cover, providing flexural and shear FRP external reinforcements and an external prestressing system, capable of restoring a satisfactory bearing capacity, according to the current national codes. The intervention has been calibrated by the former F.E. model with respect to transversal effects and influence of local and overall deformation of reinforced elements. © 2012 Taylor & Francis Group.

Subcellular localization and characterization of G protein-coupled receptor homolog from lymphocystis disease virus isolated in China

G protein-coupled receptors (GPCRs) constitute a large superfamily involved in various types of signal transduction pathways, and play an important role in coordinating the activation and migration of leukocytes to sites of infection and inflammation. Viral GPCRs, on the other hand, can help the virus to escape from host immune surveillance and contribute to viral pathogenesis. Lymphocystis disease virus isolated in China (LCDV-C) contains a putative homolog of cellular GPCRs, LCDV-C GPCR. In this paper, LCDV-C GPCR was cloned, and the subcellular localization and characterization of GPCR protein were investigated in fish cells. LCDV-C GPCR encoded a 325-amino acid peptide, containing a typical seven-transmembrane domain characteristic of the chemokine receptors and a conserved DRY motif that is usually essential for receptor activation. Transient transfection of GPCR-EGFP in fathead minnow (FHM) cells and epithelioma papulosum cyprini (EPC) cells indicated that LCDV-C GPCR was expressed abundantly in both the cytoplasm and nucleoplasm. Transient overexpression of GPCR in these two cells cannot induce obvious apoptosis. FHM cells stably expressing GPCR showed enhanced cell proliferation and significant anchorage-independent growth. The effects of GPCR protein on external apoptotic stimuli were examined. Few apoptotic bodies were observed in cells expressing GPCR treated with actinomycin D (ActD). Quantitative analysis of apoptotic cells indicated that a considerable decrease in the apoptotic fraction of cells expressing GPCR, compared with. the control cells, was detected after exposure to ActD and cycloheximide. These data suggest that LCDV-C GPCR may inhibit apoptosis as part of its potential mechanism in mediating cellular transformation.

Pulsed laser writing of holographic nanosensors

Tuneable optical sensors have been developed to sense chemical stimuli for a range of applications from bioprocess and environmental monitoring to medical diagnostics. Here, we present a porphyrin-functionalised optical sensor based on a holographic grating. The holographic sensor fulfils two key sensing functions simultaneously: it responds to external stimuli and serves as an optical transducer in the visible region of the spectrum. The sensor was fabricated via a 6 nanosecond-pulsed laser (350 mJ, λ = 532 nm) photochemical patterning process that enabled a facile fabrication. A novel porphyrin derivative was synthesised to function as the crosslinker of a polymer matrix, the light-absorbing material, the component of a diffraction grating, as well as the cation chelating agent in the sensor. The use of this multifunctional porphyrin permitted two-step fabrication of a narrow-band light diffracting photonic sensing structure. The resulting structure can be tuned finely to diffract narrow-band light based on the changes in the fringe spacing within the polymer and the system's overall index of refraction. We show the utility of the sensor by demonstrating its reversible colorimetric tuneability in response to variation in concentrations of organic solvents and metal cations (Cu 2+ and Fe2+) in the visible region of the spectrum (λmax ≈ 520-680 nm) with a response time within 50 s. Porphyrin-functionalised optical sensors offer great promise in fields varying from environmental monitoring to biochemical sensing to printable optical devices. This journal is © the Partner Organisations 2014.

Auxetic nuclei in embryonic stem cells exiting pluripotency.

Embryonic stem cells (ESCs) self-renew in a state of naïve pluripotency in which they are competent to generate all somatic cells. It has been hypothesized that, before irreversibly committing, ESCs pass through at least one metastable transition state. This transition would represent a gateway for differentiation and reprogramming of somatic cells. Here, we show that during the transition, the nuclei of ESCs are auxetic: they exhibit a cross-sectional expansion when stretched and a cross-sectional contraction when compressed, and their stiffness increases under compression. We also show that the auxetic phenotype of transition ESC nuclei is driven at least in part by global chromatin decondensation. Through the regulation of molecular turnover in the differentiating nucleus by external forces, auxeticity could be a key element in mechanotransduction. Our findings highlight the importance of nuclear structure in the regulation of differentiation and reprogramming.

Estimation of the natural purification rate of a eutrophic lake after pollutant removal

Pollution resulting from increased human activities is threatening Lake Donghu, its effects being characterized by serious eutrophication. A steady increase of phosphorus loading is the most important factor of the lake eutrophication. Pollution external control projects are being implemented and will be accomplished before the year 2010. In order to predict the restoration rate by the lake's self-purification after the projects of external control, a model of predicting the removal rate of total phosphorus (TP) from lake water is developed, and a brief method of estimating the release and export rate of sediment phosphorus is suggested. Results show that, on the premise of external loading fully controlled. The restoration needs about 55 years or more. Obviously, the great P pool in the sediment will be a limiting factor of preventing the improvement of water quality after the external loading is under control. Based on the estimation we conclude that after the external control projects before 2010, in order to restore the lake in a few years, although highly cost, the first step must be the sediment dredging to remove internal loading. The second step is diverting water of River Changjiang into the lake to accelerate the improvement of lake water. Otherwise, removal of pollutant sources will become meaningless. (c) 2006 Elsevier B.V. All rights reserved.

Photosynthetic inorganic carbon utilization of gametophytes and sporophytes of Undaria pinnatifida (Phaeophyceae)

The characteristics of inorganic carbon assimilation by photosynthesis were investigated in male and female gametophytes and juvenile sporophytes of Undaria pinnatifida. Gametophytes and sporophytes have detectable extracellular and intracellular carbonic anhydrase (CA) activity, and the CA inhibitor, acetazolamide (AZ), significantly inhibited their photosynthesis O-2 evolution. In pH-drift experiments, it was found that gametophytes did not raise the final pH of seawater above 9.00 (CO2 concentrations of about 2.2 mu M), indicating a low ability to utilize inorganic carbon. In contrast, sporophytes rapidly raised pH to over 9.53 and depleted the free CO2 Concentration to less than 0.16 mu M. The apparent photosynthetic affinity for CO2 was almost the same for gametophytes and sporophytes, whereas gametophytes had a much lower affinity for HCO3- than sporophytes. Two inhibitors of band 3 anion exchange protein (DIDS and SITS) inhibited the photosynthesis of gametophytes but not that of sporophytes. It was indicated that both gametophytes and sporophytes were capable of using HCO3-, which involved the external CA activity, and a direct HCO3- use also occurred in the former, but the latter showed a greater capacity of HCO3- use than the former. In addition, male and female gametophytes did not show great differences in the inorganic carbon uptake mechanism underlying photosynthesis.

Effect of the interplay between protein and surface on the properties of adsorbed protein layers.

Although protein adsorption to surface is a common phenomenon, investigation of the process is challenging due to the complexity of the interplay between external factors, protein and surface properties. Therefore experimental approaches have to measure the properties of adsorbed protein layers with high accuracy in order to achieve a comprehensive description of the process. To this end, we used a combination of two biosensing techniques, dual polarization interferometry and quartz crystal microbalance with dissipation. From this, we are able to extract surface coverage values, layer structural parameters, water content and viscoelastic properties to examine the properties of protein layers formed at the liquid/solid interface. Layer parameters were examined upon adsorption of proteins of varying size and structural properties, on surfaces with opposite polarity. We show that "soft" proteins such as unfolded α-synuclein and high molecular weight albumin are highly influenced by the surface polarity, as they form a highly diffuse and hydrated layer on the hydrophilic silica surface as opposed to the denser, less hydrated layer formed on a hydrophobic methylated surface. These layer properties are a result of different orientations and packing of the proteins. By contrast, lysozyme is barely influenced by the surface polarity due to its intrinsic structural stability. Interestingly, we show that for a similar molecular weight, the unfolded α-synuclein forms a layer with the highest percentage of solvation not related to surface coverage but resulting from the highest water content trapped within the protein. Together, these data reveal a trend in layer properties highlighting the importance of the interplay between protein and surface for the design of biomaterials.

Gene cloning and functional analysis of glycosaminoglycan-degrading enzyme chondroitin AC lyase from Flavobacterium columnare G(4)

The chondroitin AC lyase gene, cslA, was cloned for the first time from the fish bacterial pathogen F. columnare G(4). From the first transcription initiation site, the cslA extends 2620 nucleotides to the end of the 3' region. The open reading frame of cslA transcript has 2286 nucleotides encoding 762 amino acids with a 16 residues long signal peptide at the N-terminus. The gene, cslA was then successfully expressed in Escherichia coli and recombinant chondroitin AC lyase, rChonAC was purified, with its lytic activity analyzed. Zymography analysis copolymerized with chondroitin sulphate revealed the lytic activity of rChonAC and also the crude native ChonAC isolated from periplamic space of cultured F. columnare G(4). The low level of lytic activity observed in crude native ChonAC may be due possibly to the low level of expression of this gene in the cultured condition. The expression and the role of this virulence factor is of interest for further research on the pathogenesis of F. columnare.

Graphene modelocked VECSELs

In the past decade, passively modelocked optically pumped vertical external cavity surface emitting lasers (OPVECSELs), sometimes referred to as semiconductor disk lasers (OP-SDLs), impressively demonstrated the potential for generating femtosecond pulses at multi-Watt average output powers with gigahertz repetition rates. Passive modelocking with a semiconductor saturable absorber mirror (SESAM) is well established and offers many advantages such as a flexible design of the parameters and low non-saturable losses. Recently, graphene has emerged as an attractive wavelength-independent alternative saturable absorber for passive modelocking in various lasers such as fiber or solid-state bulk lasers because of its unique optical properties. Here, we present and discuss the modelocked VECSELs using graphene saturable absorbers. The broadband absorption due to the linear dispersion of the Dirac electrons in graphene makes this absorber interesting for wavelength tunable ultrafast VECSELs. Such widely tunable modelocked sources are in particularly interesting for bio-medical imaging applications. We present a straightforward approach to design the optical properties of single layer graphene saturable absorber mirrors (GSAMs) suitable for passive modelocking of VECSELs. We demonstrate sub-500 fs pulses from a GSAM modelocked VECSEL. The potential for broadband wavelength tuning is confirmed by covering 46 nm in modelocked operation using three different VECSEL chips and up to 21 nm tuning in pulsed operation is achieved with one single gain chip. A linear and nonlinear optical characterization of different GSAMs with different absorption properties is discussed and can be compared to SESAMs. © 2014 SPIE.

Passively modelocked VECSEL using a single-layer graphene saturable absorber mirror

Optically pumped ultrafast vertical external cavity surface emitting lasers (VECSELs), also referred to as semiconductor disk lasers (SDLs), are very attractive sources for ps- and fs-pulses in the near infrared [1]. So far VECSELs have been passively modelocked with semiconductor saturable absorber mirrors (SESAMs, [2]). Graphene has emerged as a promising saturable absorber (SA) for a variety of applications [3-5], since it offers an almost unlimited bandwidth and a fast recovery time [3-5]. A number of different laser types and gain materials have been modelocked with graphene SAs [3-4], including fiber [5] and solid-state bulk lasers [6-7]. Ultrafast VECSELs are based on a high-Q cavity, which requires very low-loss SAs compared to other lasers (e.g., fiber lasers). Here we develop a single-layer graphene saturable absorber mirror (GSAM) and use it to passively modelock a VECSEL. © 2013 IEEE.

Molecular and expression characterization of three gonadotropin subunits common alpha, FSH beta and LH beta in groupers

A SMART cDNA plasmid library was constructed from protogyous greasy grouper (Epinephelus coioides) pituitary, and the full-length cDNAs of three gonadotropin (GTH) subunits common alpha, FSH beta and LH beta were cloned and sequenced from the library. The nucleotide sequences of common alpha, FSH beta and LH beta subunit cDNAs are 647, 594 and 574 bp in length, and encode for mature peptides of 94, 99 and 115 aa, respectively. High homology was observed by amino acid sequence alignment and identity comparison of the grouper mature peptides of common alpha, FSH beta and LH beta with that of other fishes. Phylogenetic tree analyses of the three GTH mature subunits revealed similar phylogeny relationships among the studied fish species. Three polyclonal antibodies were prepared from the in vitro expressed common alpha, FSH beta and LH beta mature proteins, respectively. Western blot analysis and immunofluoresence localization were performed on two typical stages of ovarian development stages in red-spotted grouper. Significant differences in protein expression levels of three gonadotropin subunits were revealed between the two ovarian development stages. In the individuals with resting ovary, common alpha was almost not detected in pituitaries, and FSH beta and LH beta expression levels were very low. While in the individuals with developing ovary, the expression of all three gonadotropin subunits reached to a high level. Immunofluoresence localization indicated that the grouper FSH beta cells mainly distributed in the middle area of PPD, while the LH beta cells distributed more widely, including in the area similar to the FSH beta cells and at the external periphery of pituitary near to the PI side. The common alpha might be expressed in both FSH beta and LH beta cells. Double immunofluoresence localization further demonstrated FSH beta and LH beta expression in distinct cells in the PPD area, although the FSH beta and LH beta cells were detected in the identical area of PPD. (c) 2005 Elsevier Ireland Ltd. All rights reserved.

Studies on the food web structure of Lake Donghu using stable carbon and nitrogen isotope ratios

Food web structure was studied by using carbon and nitrogen isotope ratios in a hypereutrophic subtropical Chinese lake, Lake Donghu. High external nutrient loading and the presence of abundant detritus from submersed macrophytes were responsible for the high sediment delta(15)N and delta(13)C, respectively. C-13 was significantly higher in submersed macrophytes than in other macrophytes. The similar delta(13)C values in phytoplankton, zooplankton, zoobenthos, and planktivorous fish indicate that phytoplankton was the major food source for the consumers. By using a delta(15)N mass balance model, we estimate that the contributions of zooplankton to the diet of silver carp and bighead carp were 54% and 74%, respectively, which is in agreement with previous microscopic observations on intestinal contents of these fishes.

Climbing vertical terrains with a self-contained robot

Vertical climbing on a variety of flat surfaces with a single robot has been previously demonstrated using vacuum suction, electrostatic adhesion, and biologically inspired approaches, etc. These methods generally have a low attachment strength, and it is not clear whether they can provide satisfactory attachment on vertical terrains with richer 3D features. Recent development of a climbing technology based on hot melt adhesives (HMAs) has shown its advantage with a high attachment strength through thermal bonding and viability to any solid surfaces. However, its feasibility for vertical climbing has only been proven on flat surfaces and with external energy supplies. This paper provides quantitative measurements for vertical climbing performance on five types of surfaces and terrains with a self-contained robot exploiting HMAs. We show that robust vertical climbing on multiple terrains can be achieved with reliable high-strength attachment. © 2012 IEEE.