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Two novel 2,6-dichloroisonicotinic acid (INA) derivatives [trifluoroethyl 2,6-dichloroisonicotinate (TFINA) and 2-(2,6-dichloro-pyridine-4-carbonyloxy)-ethyl jasmonate (DPCEJ)] were chemically synthesized and evaluated by bioassay as potential elicitors for inducing the biosynthesis of plant secondary metabolites. A suspension culture of Taxus chinensis, which stably produces a high level of bioactive taxuyunnanine C (Tc), was taken as a model plant cell system. A significant increase in Tc accumulation was observed in the presence of TFINA or DPCEJ. For example, addition of 100 μM TFINA or DPCEJ on day 7 led to a high Tc content of 21.6±2.0 or 27.7±1.0 mg g−1 (on day 21), while the Tc content was 13.7±1.0 and 17.1±0.9 mg g−1 for the control and that with addition of 100 μM INA, respectively. To the best of our knowledge, this is the first report on the use of synthetic INA derivatives for inducing the biosynthesis of plant secondary metabolites. The results indicate that the newly synthesized INA analogues can act as promising elicitors for secondary metabolism induction in plant cell cultures. [ABSTRACT FROM AUTHOR]

A fluorescent ratiometric Hg2+ ion sensor RMS, based on a coumarin platform coupled with a tetraamide receptor, is presented. This sensor, employing the ICT mechanism, could be used to specifically detect Hg2+ ions in a neutral buffered water solution with an ∼100-nm blue shift in emission spectra. [ABSTRACT FROM AUTHOR]

Chemically synthesized 2-hydroxyethyl jasmonate (HEJA) was for the first time employed to induce the ginsenoside biosynthesis and to manipulate the product heterogeneity in plant cell cultures. The dose response and timing of HEJA elicitation were investigated in cell suspension cultures of Panax notoginseng. The optimal concentration and timing of HEJA addition for both cell growth and ginsenoside accumulation was identified to be 200 μM added on day 4. It was interestingly found that HEJA could stimulate ginsenosides biosynthesis and change their heterogeneity more efficiently than methyl jasmonate (MJA), i.e., the total ginsenoside content and the Rb/Rg ratio increased about 60 and 30% with HEJA elicitation than that by MJA, respectively. The activity of Rb1 biosynthetic enzyme, i.e., UDPG-ginsenoside Rd glucosyltransferase (UGRdGT), was also higher in the former case. A maximal production titer of ginsenoside Rg1, Re, Rb1, and Rd was 47.4±4.8, 52.3±4.4, 190±18, and 12.1±2.5 mg/l with HEJA elicitation, which was about 1.3-, 1.3-, 1.7-, and 2.1-fold than that using MJA, respectively. Early signal events in plant defense response, including oxidative burst and jasmonic acid (JA) biosynthesis, were also examined. Levels of H2O2 and NO in medium and l-phenylalanine ammonia lyase activity in cells were not affected by addition of MJA and HEJA. On the other hand, the JA content in cells was increased with external jasmonates elicitation, and it was inhibited with the addition of JA biosynthesis inhibitors. The results suggest that oxidative burst might not be involved in the jasmonates-elicited signal transduction pathway, and MJA and HEJA may induce the ginsenoside biosynthesis via induction of endogenous JA biosynthesis and key enzymes (such as UGRdGT) in the ginsenoside biosynthetic pathway of P. notoginseng cells. The information is useful for hyperproduction of plant-specific heterogeneous products. [ABSTRACT FROM AUTHOR]

Summary. Novel fluorescent conjugates of uridine nucleoside and 4-dimethylamino-1,8-naphthalimide via linkage with different length, and their precursors were synthesized. Their spectroscopic properties were examined in ten different solvents. It was found that the spectroscopic properties for these conjugates are strongly dependent on polarity and hydrogen bonding ability of solvents. Their fluorescence spectra are also strongly influenced by intramolecular aromatic stacking and hydrogen bonding between the base or sugar moiety of the uridine nucleoside and naphthalimide moiety, which is controlled by the length of the linker. [ABSTRACT FROM AUTHOR]

GFRP (glass-fiber-reinforced polymer), as a composite material, possesses many favorable properties including high strength and low weight and is amenable to unique processing methods; therefore, it is a potential free-form surface material. However, the complex design theory owing to anisotropy limits its application. Thus, a simplified material solution becomes significant. In this study, the strength and stiffness of orthotropic symmetrical GFRP laminates are derived theoretically, and a simplified material solution is proposed to simplify the anisotropy as isotropy. Then, using the numerical simulation of an actual orthotropic symmetrical GFRP laminate free-form facade structure, the effectiveness of the simplified material solution is analyzed and evaluated. This solution can provide guidance for similar GFRP facades and further promote the application of GFRP in engineering.

A new probe based on the Gabriel mechanism was designed and first used for hydrazine detection with high selectivity against other amines in aqueous solution. Importantly, the probe could be used for gas-state discrimination of hydrazine with different concentrations. Additionally, probe 1 could also be applied for the imaging of hydrazine in living cells. [ABSTRACT FROM AUTHOR]

The FRP-steel girder composite bridge system is increasingly used in new constructions of bridges as well as rehabilitation of old bridges. However, the understanding of composite action between FRP decks and steel girders is limited and needs to be systematically investigated. In this paper, depending on the experimental investigations of FRP to steel girder system, the Finite Element (FE) models on experiments were developed and analyzed. Comparison between experiments and FE results indicated that the FE models were much stiffer for in-plane shear stiffness of the FRP deck panel. To modify the FE models, rotational spring elements were added between webs and flanges of FRP decks, to simulate the semirigid connections. Numerical analyses were also conducted on four-point bending experiments of FRP-steel composite girders. Good agreement between experimental results and FE analysis was achieved by comparing the load-deflection curves at midspan and contribution of composite action from FRP decks. With the validated FE models, the parametric studies were conducted on adhesively bonded connection between FRP decks and steel girders, which indicated that the loading transfer capacity of adhesive connection was not simply dependent on the shear modulus or thickness of adhesive layer but dominated by the in-plane shear stiffness K.

A new fluorescent Pd2+sensor 1, N-butyl-4-(p-methyloxy)-phenylethynyl-5-thiophenemethylamino-1,8-naphthalimide, was designed and synthesized. It showed highly selective on–off fluorescence changes for Pd2+among the representative transition and heavy metallic cations, and its fluorescence was efficiently quenched by 5 equivalents of Pd2+in buffer solution. The sensor also displayed a selective chromogenic behavior toward Pd2+from yellow to black-red, which could be easily observed by the naked eye. [ABSTRACT FROM AUTHOR]

Bulky 4-tritylphenylethynyl substituted boradiazaindacene with pure red emission, relatively large Stokes shift, high fluorescence quantum yield, and low self-quenching was efficiently synthesized and qualified as a potential EL dopant. [ABSTRACT FROM AUTHOR]

Replacement of the oxygen with a silicon atom on the rhodamine framework produces a strong red-emission fluorophore which has a high molar extinction coefficient and 90 nm red shift relative to rhodamine dye PY. [ABSTRACT FROM AUTHOR]

To investigate the mechanical degradation of the shear properties of glass fiber-reinforced polymer (GFRP) laminates in bridge decks under hygrothermal aging effects, short-beam shear tests were performed following the ASTM test standard (ASTM D790-10A). Based on the coupled hygro-mechanical finite element (FE) analysis method, an inverse parameter identification approach based on short-beam shear tests was developed and then employed to determine the environment-dependent interlaminar shear modulus of GFRP laminates. Subsequently, the shear strength and modulus of dry (0% Mt/M∞), moisture unsaturated (30% Mt/M∞ and 50% Mt/M∞), and moisture saturated (100% Mt/M∞) specimens at test temperatures of both 20 °C and 40 °C were compared. One cycle of the moisture absorption–desorption process was also investigated to address how the moisture-induced residual damage degrades the shear properties of GFRP laminates. The results revealed that the shear strength and modulus of moisture-saturated GFRP laminates decreased significantly, and the elevated testing temperature (40 °C) aggravated moisture-induced mechanical degradation. Moreover, an unrecoverable loss of shear properties for the GFRP laminates enduring one cycle of the moisture absorption–desorption process was evident.

Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP) laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test standard (ASTM D790-10A). The flexural properties of dry (0% Mt/M∞), moisture unsaturated (30% Mt/M∞ and 50% Mt/M∞) and moisture saturated (100% Mt/M∞) specimens at both 20 and 40 °C test temperatures were compared. One cycle of moisture absorption-desorption process was considered in this study to investigate the mechanical degradation scale and the permanent damage of GFRP laminates induced by moisture diffusion. Experimental results confirm that the combination of moisture and temperature effects sincerely deteriorates the flexural properties of GFRP laminates, on both strength and stiffness. Furthermore, the reducing percentage of flexural strength is found much larger than that of E-modulus. Unrecoverable losses of E-modulus (15.0%) and flexural strength (16.4%) for the GFRP laminates experiencing one cycle of moisture absorption/desorption process are evident at the test temperature of 40 °C, but not for the case of 20 °C test temperature. Moreover, a coupled hygro-mechanical Finite Element (FE) model was developed to characterize the mechanical behaviors of GFRP laminates at different moisture absorption/desorption stages, and the modeling method was subsequently validated with flexural test results.

The research presented in this paper is an experimental study and numerical analysis on mechanical behavior of the adhesively-bonded joint between FRP sandwich bridge deck and steel girder. Generally, there are three typical stress states in the adhesively-bonded joint: shear stress, tensile stress, and combination of both. To realize these stress states in the adhesively-bonded joint during tests, a specific loading device is developed with the capacity of providing six different loading angles, which are 0°(pure tension), 18°, 36°, 54°, 72° and 90°(pure shear). Failure modes of adhesively-bonded joints are investigated. It indicates that, for the pure shear loading, the failure mode is the cohesive failure (near the interface between the adhesive layer and the steel support) in the adhesive layer. For the pure tensile and combined loading conditions, the failure mode is the combination of fiber breaking, FRP delamination and interfacial adhesion failure between the FRP sandwich deck and the adhesive layer. The load-bearing capacities of adhesive joints under combined loading are much lower than those of the pure tensile and pure shear loading conditions. According to the test results of six angle loading conditions, a tensile/shear failure criterion of the adhesively-bonded joint is obtained. By using Finite Element (FE) modeling method, linear elastic simulations are performed to characterize the stress distribution throughout the adhesively-bonded joint.

A non-covalent interactions' concept for proteins' fluorescent sensor of solvent-sensitive naphthalimide dyes was developed on basis of enzyme-inhibitor principle, which could selectively bind certain hydrolases with significant fluorescence enhancements and apparent blue-shifts in emission wavelength. [ABSTRACT FROM AUTHOR]

The design and synthesis of a sensitive and selective fluorescent sensor is a fundamental goal for organic and analytical chemists. So far, the development of practical fluorescent chemosensors for many heavy and transition metal ions is still a challenge. The detection of mercury ion is attracting attention, as mercury and its derivatives are widely used in industry and they have inherent high toxicity. There were some examples of fluorescent quenching chemosensors for mercury ion in organic or aqueous solution. However, there are few chemosensors with fluorescence enhancement for mercury ion in organic solutions, and few in aqueous solutions.

Fluorescent imaging of acute mercuric chloride exposure on cultured human kidney tubular epithelial cells.Background.Imaging of intracellular mercuric ion is necessary for mechanism of renal toxicity of exposure to HgCl2. The distribution of Hg2+ inside a living cell, however, is still invisible due to the lack of high selective and sensitive fluorescent molecular probe for Hg2+.Methods.A new fluorescent probe, EPNP, was applied to the cultured cells of human kidney proximal tubular epithelial cell line (HKC) in the presence of HgCl2 and some other bivalent ions. The relative fluorescence intensity of EPNP was measured and fluorescence images were taken by laser scanning confocal microscope.Results.Results showed it led to an Hg2+ concentration- and time-dependent increase in fluorescence intensity, and responded weakly for some other heavy and transition metal ions. It could be seen during acute exposure on HKC cells, Hg2+ locate perinuclear, and on nuclear membrane, which was beyond what one knew before.Conclusion.EPNP is a real-time and on-line probe for imaging Hg2+ in a living cell due to its high selectivity and sensitivity for Hg2+ and slow bleaching/fading. Both the probe and the new results about the distribution of intracellular Hg2+ may be helpful for relevant biologic research. [ABSTRACT FROM AUTHOR]

We have revisited the synthesis of a series of ICT fluorophores, which were reported to have a core structure of 8-oxo-8H-acenaphtho[1,2-b]pyrrol-9-carbonitrile. However, based on the 2D NMR and X-ray diffraction analysis, their core structure was corrected as 1-oxo-1H-phenalene-2,3-dicarbonitrile (1). Compound 1 shows a highly electron-deficient nature and can easily undergo oxidative SNArH reaction on the naphthyl ring to produce a series of novel ICT fluorophores. The regioselectivity of this substitution reaction was studied by introduction of representative nucleophiles. Moreover, due to the strong rigidity and efficient ICT nature, the obtained fluorescent dyes display very good spectroscopic properties even in an aqueous environment. [ABSTRACT FROM AUTHOR]

It is still a significant challenge to develop a Zn2+-seIective fluorescent sensor with the ability to exclude the interference of some heavy and transition metal (HTM) ions such as Fe2+, Co2+, Ni2+, Cu2+, Cd2+, and Hg2+. Herein, we report a novel amide-containing receptor for Zn2+, combined with a naphthalimide fluorophore, termed ZTRS. The fluorescence, absorption detection, NMR, and IR studies indicated that ZTRS bound Zn2+ in an imidic acid tautomeric form of the amide/di-2-picolylamine receptor in aqueous solution, while most other HTM ions were bound to the sensor in an amide tautomeric form. Due to this differential binding mode, ZTRS showed excellent selectivity for Zn2+ over most competitive HIM ions with an enhanced fluorescence (22-fold) as well as a red-shift in emission from 483 to 514 nm. Interestingly, the ZTRS/Cd2+ complex showed an enhanced (21-fold) blue-shift in emission from 483 to 446 nm. Therefore, ZTRS discriminated in vitro and in vivo Zn2+ and Cd2+ with green and blue fluorescence, respectively. Due to the stronger affinity, Zn2+ could be ratiometrically detected in vitro and in viva with a large emission wavelength shift from 446 to 514 nm via a Cd2+ displacement approach. ZTRS was also successfully used to image intracellular Zn2+ ions in the presence of iron ions. Finally, we applied ZTRS to detect zinc ions during the development of living zebrafish embryos. [ABSTRACT FROM AUTHOR]

The article presents a study on a new flourescent sensor based on boron dipyrromethene (BODIPY) flourophore for Cadmium (Cd) in aqueous solution and living cell. It states that the said flourescent sensor shows high sensitivity and selectivity toward Cd2+ in aqueous solution. It mentions that the flourescence intensity was substantially improved about 195-fold and the quantum yield increased almost 100-fold.