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Fluorescence resonance energy transfer (FRET) is often applied to construct fluorescent probes for acquiring high selectivity and sensitivity. According to the FRET theory, a homodimer composed of two identical fluorophores with a small Stokes shift has only weak fluorescence due to homo-FRET between fluorophores, and the fluorescence could be recovered after the destruction of the homodimer. In this study, we designed and synthesized a homodimer fluorescent probe, namely 1,3,5,7-tetramethyl-8-(4'-phenylthiophenol)-boron difluoride-dipyrrole methane dimer (D-TMSPB), based on this turn-on strategy. In D-TMSPB, the disulfide moiety was selected as the response moiety of biothiols, and BODIPY fluorophore was chosen as both donor and acceptor in FRET due to the ultra-small Stokes shifts and obvious overlap of its excitation/emission peak. D-TMSPB exhibited only weak fluorescence. After selective reaction with biothiols, FRET was destroyed and the derivative exhibited strong fluorescence at 514 nm with the limit of detection of about 0.15 μM for GSH. Notably, the derivative of biothiols shows remarkable fluorescence only in acidic conditions, which accords with the internal environment of lysosome. Thus, D-TMSPB was applied to image the biothiols of lysosome in living cells. The turn-on fluorescence of D-TMSPB indicated that homo-FRET is a practical strategy to design turn-on fluorescent probes, particularly for the sensing mechanism based on leaving groups.

1,3-Dienes are versatile synthons and important monomers. Herein we report a carbon dioxide promoted dehydration reaction of primary allylic alcohols to produce substituted 1,3-dienes in good yields. Taking advantage of carbon dioxide as a promoter to facilitate the alcoholic C–O bond cleavage via the formation of an allylic bicarbonate ester, this reaction proceeds under mild conditions.

A facile and straightforward strategy was used to prepare carbon dots (CDs) using catechol as carbon source in one-pot hydrothermal method. The synthesis method is simple without any doping and modification and the prepared CDs do not require any post-processing. Characterizations of the obtained CDs indicated that they had high crystallinity and higher quantum yield (QY, 32%) than most non-functionalized and non-doped CDs. Noticeably, the fluorescence of CDs could be quenched with hypochlorite (ClO−) by oxidation of the residual pyrocatechol groups on the surface to o-benzoquinone exhibiting high sensitivity and selectivity for ClO−. The assay covered a linear range from 0.1 to 10 μM with a low detection limit of 30 nM. The results showed that the CDs provided a promising potential tool for the detection of ClO− in real water samples.

In this study, we synthesized metal–organic frameworks (MOFs) UiO-67-bpydc using H2bpydc as ligands and Zr6 clusters as vertexes. Due to the protonation of the bipyridine group, UiO-67-bpydc shows pH-dependent fluorescence (365 nm/530 nm) in the pH range from 1 to 9, which shows its feasibility as a wide-range pH sensor. Further study indicated that UiO-67-bpydc exhibits stability, reusability, selectivity and has an excellent linear relationship in the pH range 4.0–6.5, and the mechanism of the UiO-67-bpydc fluorescence intensity with the variation of pH has been studied in detail. This MOF-based fluorescent sensor has been applied to specifically detect the pH of solutions in the presence of the body fluid matrix. Compared with reported pH-MOF sensors, UiO-67-bpydc can be practically applied in real samples and is easily prepared with excellent stability in different buffer solutions.

Catecholamines such as dopamine, norepinephrine and epinephrine are important neurotransmitters containing cis-diol moieties, and HPLC with fluorescence detection (HPLC-FD) has been successfully used as highly sensitive detection method for them. However, the complex matrix of biological samples is always a challenge. Boronate affinity microextraction is practical to purify and enrich cis-diol compounds. In this study, we used in-situ derivatization in boronate affinity polymer monolith microextraction (BA/PMME) to combine sample pretreatment and derivatization, then followed by HPLC-FD to develop a highly sensitive and selective determination method for catecholamines. Taking poly(3-acrylamidophenyl boronic acid-co-ethylene dimethacrylate) as BA/PMME material and TMBB-Su as labeling reagent, catecholamines could be derivatizated in polymer monolith in-situ together with the sample enrichment and purification. Comparing with commonly used solid phase extraction followed by derivatization, fewer operation steps are required and higher sensitivity was obtained with LODs as low as 0.06–0.2 nM.

Carbonyl compounds are widely distributed in organisms, and the commonly used methods for determination of them like UV/fluorescence/mass spectrometry always require derivatization reagents. However, the reported derivatization reagents have significant difference in reactivity, which is very unfavorable for developing highly reactive reagent. In this study, we theoretically investigated the factors affecting the reactivity of hydrazine-based derivatization reagents, and proposed a strategy for filtering highly reactive reagents by quantum chemical calculation. With this strategy, N-propyl-4-hydrazino-1,8-naphthalimide (NPHNA) was filtered out as a fluorescent derivatization reagent. Taking aliphatic aldehydes as representatives, we evaluated the reactivity of NPHNA for carbonyl compounds. The derivatization of NPHNA with aliphatic aldehydes could be finished at room temperature within 60 min or 35 °C within 35 min, which showed higher reactivity than the most popular UV/MS reagent, 2,4-dinitrophenylhydrazine (DNPH). We believe that the strategy we proposed in this work is of great potential to design highly reactive UV/fluorescent/MS labeling reagents for carbonyl compounds and even other analytes.

A micro-arc oxidation (MAO)/zinc stearate (ZnSA) composite coating was fabricated via MAO processing and subsequent sealing with electrodeposition of a superhydrophobic ZnSA. The surface morphologies, chemical composition and corrosion resistance of the coatings were investigated using field-emission scanning electron microscopy, Fourier transform infrared, X-ray diffraction and electrochemical and hydrogen evolution measurements. Results indicated that the MAO coating was efficiently sealed by the following superhydrophobic ZnSA coating. The MAO/ZnSA composite coating significantly enhanced the corrosion resistance of Mg alloy Mg-4Li-1Ca due to its superhydrophobic function. Additionally, corrosion mechanism was suggested and discussed for the composite coating.

Multiwalled carbon nanotubes (MWCNTs) as an excellent supporter covered with a thick layer of cobalt phthalocyanine (CoPc) were prepared by in-situ synthesis. Platinum particles were adopted to enhance the conductivity of CoPc-MWCNTs. The final nanocomposite Pt-CoPc-MWCNTs was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Strong aromatic π-π stacking between MWCNTs and CoPc made CoPc in-situ forming on MWCNTs. With homogeneous thickness of CoPc covered on the MWCNTs and Pt particles equally distributed, the nanocomposite was used as electrocatalyst. The electrochemical properties of the composite got researched by casting the dispersion of Pt-CoPc-MWCNTs on the glassy carbon electrode. Compared with other modified electrodes, Pt-CoPc-MWCNTs/GC electrode exhibited excellent electrochemical activity towards dopamine (DA) and uric acid (UA). Linear responses for DA and UA were obtained in the ranges of 5 to 170 μM and 5 to 100 μM, and limits of detection were 2.6 and 1.4 μM (S/N= 3), respectively. Simultaneous detection of DA and UA in the presence of ascorbic acid (AA) also displayed selective property, with no interference to each other.

N-butyl Pyridine Nitrate ionic liquid is prepared by the double decomposition reaction of BPC and NaNO3. The ionic liquid at room temperature used in the experiment has a significant absorption determined by UV spectrum within the range of 200-400nm, the maximum absorption wavelength of BP-NO3ionic liquid is 256nm. The standard working curve of BP-NO3ionic liquid is y= 0.06848x + 0.04427(R=0.99913). The recovery rate of BP-NO3ionic liquid which is between 100.2% and 102.4%, is measured by standard addition method in water.

1-methyl-3-butyl Imidazole chloride is prepared by 1–methyl imidazole and chlorinated n-butane. The synthesis reaction of 1-methyl-3-butyl imidazole tetrafluoroborate is in the acetone. The solubility of NaNO3and BMIC in acetone is not large, but due to the insolubility in acetone of reaction product NaCl and continuous precipitation from the liquid phase in the reaction process, so as to promote the reaction continuously towards forward direction. The colorless transparent and odorless BMINO3are gotten. We use infrared spectrometer for the structure characterization, it is proved that we have gotten BMINO3room temperature ionic liquids. BMIC and BMINO3ionic liquids have better solubility in H2O, ethanol, ethyl acetate, acetone, acetonitrile, and methanol, and is insoluble in the ether and cyclohexane.

Titanium tetrachloride with inorganic salts as raw materials in the experiment, TiO2is prepared by the hydrolyzation method in (NH4)2SO4-modified TiCl4solution, the maximal photocatalytic activity is observed at the mole ratio of TiCl4: (NH4)2SO4=1:2, the water-bath temperature of 90°C. Bromophenol blue solution is degraded by the nanometer TiO2. The photocatalytic degradation efficiency is influenced by the nanometer TiO2amount, irradiation time, the UV irradiation intensity and solution temperature. The short degradation time shows that the nanometer TiO2can be used as an easy and efficient method to degrade bromophenol blue solution.

This paper explores the sol-gel titanium dioxide the conditions of experiments to determine the best conditions. The photodegradation capability of alizarin red has been enhanced by using immobilized TiO2 particles, where the titanium sol synthesized by a sol-gel method was used as the binder for the immobilization. Optimal conditions of TiO2 film, alizarin red concentration, solution pH, and UV irradiation intensity have been found to enhance the photodegradation efficiency.

In this paper, titanium tetrachloride with inorganic salts as raw materials in the experiment, TiO2is prepared by the hydrolyzation method in (NH4)2SO4-modified TiCl4solution, the maximal photocatalytic activity is observed at the mole ratio of TiCl4: (NH4)2SO4=1:2, the water-bath temperature of 90°C. The photocatalytic degradation efficiency is influenced by the initial cresol red concentration, the solution pH, irradiation time and the UV irradiation intensity. The short degradation time shows that the nanometer TiO2can be used as an easy and efficient method to degrade the cresol red solution in wastewater.

Rat/mouse hemokinin-1 (r/m HK-1), human hemokinin-1 (h HK-1) and human hemokinin-1(4-11) (h HK-1(4-11)) are members of the tachykinin family. In the present study, the coronary vascular activities and cardiac functions of r/m HK-1, h HK-1 and h HK-1(4-11) were investigated in isolated, spontaneously beating guinea pig hearts. Bolus injections of r/m HK-1 caused decrease in perfusion pressure indicative of coronary vasodilation, which was primarily due to the action on tachykinin NK1 receptors on vascular endothelial cells, causing the release of nitric oxide that relaxed the coronary vessels. H HK-1 caused biphasic perfusion pressure changes that were coronary vasodilation followed by coronary vasoconstriction. The mechanisms involved in the vasodilation induced by h HK-1 were similar to that of r/m HK-1 while the mechanisms for coronary vasoconstriction were mediated through the activation of tachykinin NK2 receptors on coronary sympathetic neurons to release catecholamines. H HK-1(4-11) only produced coronary vasoconstriction and the mechanisms involved in this effect were similar to that of h HK-1 in vasoconstriction. Moreover, r/m HK-1 and h HK-1 produced similar decreases in heart rate indicative of negative chronotropic responses and the decreases were mainly mediated through the activation of tachykinin NK1 receptors to release ACh acting on muscarinic receptors. H HK-1(4-11) also produced negative chronotropic response, which was mainly mediated through tachykinin NK2 receptors and muscarinic receptors. Our present results provide evidence that all of the three tachykinins could influence cardiac function and coronary vascular activity in the isolated guinea pig heart.

We propose new coefficients for the Sellmeier equations of 1.0 mo1% Mg-doped stoichiometric LiTaO3. The extraordinary refractive indices for the wavelength range 0.5?4.0?m and for temperature 30?170?C are based on measured data derived from quasi-phase-matched (QPM) optical parametric oscillator (OPO) and second-harmonic generation (SHG) based on periodically poled Mg-doped stoichiometric LiTaO3 with a pump wavelength of 1064 nm. The corrected refractive indices are in good agreement with our experimental data obtained from QPM OPO and SHG pumped at 1064?m at different temperatures.

Rat/mouse hemokinin-1 (r/m HK-1) has been identified as a member of the tachykinin family and its effect in colonic contractile activity remains unknown. We investigated the effects and mechanisms of actions of r/m HK-1 on the mouse colonic contractile activity in vitro by comparing it with that of substance P (SP). R/m HK-1 induced substantial contractions on the circular muscle of mouse colon. The maximal contractile responses to r/m HK-1 varied significantly among proximal-, mid- and distal-colon, suggesting that the action of r/m HK-1 was region-specific in mouse colon. The contractile response induced by r/m HK-1 is primarily via activation of tachykinin NK1 receptors leading to activation of cholinergic excitatory pathways and with a minor contribution of NK2 receptors, which may be on the smooth muscle itself. A direct action on colonic smooth muscles may be also involved. In contrast, SP induced biphasic colonic responses (contractile and relaxant responses) on the circular muscle, in which the contractile action of SP was equieffective with r/m HK-1. SP exerted its contractile effect predominantly through neural and muscular tachykinin NK1 receptors, but unlike r/m HK-1 did not appear to act via NK2 receptors. The relaxation induced by SP was largely due to release of nitric oxide (NO) produced via an action on neural NK1 receptors. These results indicate that the receptors and the activation properties involved in r/m HK-1-induced mouse colonic contractile activity are different from those of SP.