Selective Photocatalytic Transformation of Lignin to Aromatic Chemicals by Crystalline Carbon Nitride in Water-Acetonitrile Solutions.

The photocatalytic conversion of lignin to aromatic compounds in aqueous solutions is a promising approach. We herein report a crystalline carbon nitride prepared by high-temperature thermal polymerization and alkali-metal molten salt treatment, which was then applied in the selective conversion of lignin to aromatic compounds. The results showed that the tri-s-tri-C3N4 presented a relatively high activity and selectivity for the conversion of lignin in aqueous solutions. In a 95% water-acetonitrile solution, it achieved a relatively high conversation rate of lignin, reaching 62.00%, and the selectivity of the C-C bond cleavage was high, at 86.8%. The characterization results obtained by TEM, UV-vis/DRS, PL, and transient photocurrent response showed that the ultra-high activity of tri-s-tri-C3N4 was mainly due to the improvements in crystallinity and light absorption. Mechanism studies showed that the dispersion of the catalyst and the combination of lignin and catalyst in aqueous solvents with different acetonitrile ratios were the main factors affecting lignin conversion. As the water content in the solutions increased, the primary active sites were converted from h+ to ·O2-. This study revealed the interactions between lignin, photocatalysts, and reaction solutions, providing a theoretical basis for the photocatalytic conversion of lignin in aqueous solutions.

Fabrication of a near-infrared excitation surface molecular imprinting ratiometric fluorescent probe for sensitive and rapid detecting perfluorooctane sulfonate in complex matrix.

Construction of fluorescent probe for highly sensitive and selective detection of perfluorooctane sulfonate (PFOS) in water and biological samples is a very important strategy in related pollutant monitoring and environmental health risk appraisal. To overcome the drawback of low sensitivity caused by high-back ground signal of the conventional sensor, a molecularly imprinted near-infrared excitation ratiometric fluorescent probe was constructed and employed to determine PFOS. The sensing process was achieved through the selectively recognition of specific cavities in the probe surface with analyte, accompanied by fluorescence quenching due to the photoinduced electron transfer effect between upconversion materials and PFOS. Under optimized experimental conditions, the fluorescence quenching efficiency of the probe has good linearity against the concentrations of PFOS response divided into two segments within linear ranges of 0.001-0.1 nmol/L and 0.1-1 nmol/L, respectively, with low detection limit of 1 pmol/L. Selective experiment results indicate that the C-F chain length plays a dominant role in molecular recognition and high sensitively detection. The fabricated probe shows well detection performance in a wide pH range. Furthermore, real samples analyses indicate that such an efficient fluorescent probe has potentials in PFOS determination in surface water, human serum and egg extract sample analyses.

Selective extraction of perfluorooctane sulfonate in real samples by superparamagnetic nanospheres coated with a polydopamine-based molecularly imprinted polymer.

Superparamagnetic core-shell structured molecularly imprinted polydopamine nanospheres were constructed via self-polymerization of dopamine to attach the template onto the surface of magnetic Fe3 O4 substrate in tris-HCl solution. Then they were used for the specific recognition and extraction of perfluorooctane sulfonate from environmental water and human serum samples. The structural features and morphological characterization of the magnetic imprinting nanospheres were assessed, indicating that the magnetic polydopamine imprinted composite was successfully prepared and featured excellent magnetic separation characteristics. Adsorption experiments revealed that the magnetic adsorbents exhibited rapid adsorption kinetics and highly selective recognition properties toward perfluorooctane sulfonate. The stability and regeneration experiments indicated the materials had repeatable activity retention after repeated reuse. As a magnetic solid-phase extraction adsorbent, it was successfully applied for the extraction and quantification of perfluorooctane sulfonate in environmental water and human serum samples combined with liquid chromatography tandem mass spectrometry, with recoveries of ∼70-101.5% obtained in real samples. These results demonstrate that the prepared magnetic imprinting nanospheres are effective for the selective separation of perfluorooctane sulfonate from real samples. The synthesis technique is an effective and facile method that is conducted in aqueous solution and at ambient temperature, which is low cost, environmentally benign, and easy for scaling-up.

Indoor formaldehyde removal by three species of Chlorphytum Comosum under the long-term dynamic fumigation system.

Gaseous formaldehyde removal efficiency and physiological characteristics of leaves were investigated through a dynamic fumigation system. Three different species of potted Chlorophytum Comosum, (Green Chlorophytum Comosum for its green leaves), CC (Combined the leaves of Chlorophytum Comosum with leaves half green and half white) and PC (Purple Chlorophytum Comosum for its purple leaves), were exposed to formaldehyde for 7 days. The results showed formaldehyde removal efficiencies in the daytime were 71.07% ± 0.23, 84.66% ± 0.19, and 46.73% ± 0.15 at 1 ppm for GC, CC, and GC plants, respectively, and were 36.21% ± 0.24, 62.15% ± 0.19, and 34.97% ± 0.11 at night. This might be due to higher plant physiological activities (e.g., photosynthesis, respiration, and transpiration) during the daytime than at night. Ten physiological indicators of leaves were chosen to evaluate the 7-day fumigation process, which were chlorophyll, free protein, relative conductivity, malondialdehyde (MDA), hydrogen peroxide (H2O2), hydroxyl radical, superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and total antioxidant capacity (T-AOC). Eight of these indicators increased, while chlorophyll decreased by 22.16%, 6.95%, and 25.32%, and CAT decreased by 18.9%, 17.8%, and 25.30% for GC, CC, and PC respectively. Among all the increasing physiological indicators, relative conductivity and MDA showed the greatest increase by 279.32% and 155.56% for PC. A 15-day recovery study was also conducted using MDA and T-AOC as indicators. The results showed that all the tested plants could be tolerant up to the 8 ppm of formaldehyde concentration for 7 days under dynamic fumigation and needed 10-15 days for self-recovery.

Nitrogen-doped carbon dots as an effective fluorescence enhancing system for the determination of perfluorooctyl sulfonate.

Nitrogen-doped carbon dots (NCDs) were synthesized via hydrothermal treatment of vitamin B1 and triethylamine. The NCDs exhibit strong blue fluorescence (with a peak at 437 nm at an excitation wavelength of 370 nm), good water solubility and excellent fluorescence stability in the pH 3~12 range, at ionic strengths between 0.01 and 1 M, and under UV illumination for 6 h, as well as incubation temperature of 15~60 °C. The nanoparticles respond selectively and sensitively to trace concentrations of perfluorooctane sulfonate (PFOS) through electrostatic interactions between PFOS and NCDs. This is accompanied by the aggregation of NCDs to yield enhanced fluorescence. The nanoprobe has high selectivity for PFOS even in presence of other common ions such as metal ions, anions, and structural analogues such as surfactants. Under the optimal conditions, the response is linear in the 0.3 to 160 nM PFOS concentration range with a detection limit of 0.3 nM. Satisfactory results were achieved for determination of PFOS in spiked real water samples. Graphical abstract Schematic presentation of the synthetic route to nitrogen-doped carbon dots (NCDs) starting from vitamin B1 and triethylamine, and its application for selective and sensitive fluorometric determination of perfluorooctane sulfonate (PFOS).

Surface molecular imprinting on carbon microspheres for fast and selective adsorption of perfluorooctane sulfonate.

Perfluorooctane sulfonate (PFOS) is a persistent organic pollutant with high biological and chemical stability. It is important to develop fast and selective adsorption method for PFOS wastewater treatment. In this study, novel molecularly imprinted polymer (MIP) for PFOS adsorption was prepared. To obtain rapid adsorption kinetics, the MIP has been designed as the surface polymer using the carbon microsphere as carrier (MIP-CMSs). To ensure high adsorption selectivity to the template, two monomers with different functional structures, namely methacryloyloxyethyl trimethyl ammonium chloride (DMC) and 2-(trifluoromethyl)acrylic acid (TFMA), were employed as bi-functional monomers. The structure and morphology of MIP-CMSs were characterized using field emission scanning electron microscopy with the energy dispersive spectrometer, transmission electron microscopy, and Fourier transformation infrared spectroscopy. Based on the adsorption experiments, it was concluded that MIP-CMSs had specific binding property for PFOS on acidic condition. The adsorption equilibrium time was 1h, while the adsorption capacity was 75.99 mg g-1 at pH 3. Coexistence with contaminants with different structures had little influence on the selectivity for PFOS. The spent MIP-CMSs could be regenerated by the methanol and acetic acid mixed solution. The electrostatic interaction and molecular size played important roles in recognizing the target compound in the adsorption process.

Multichannel Luminescence Properties of Mixed-Valent Eu2+/Eu3+ Coactivated SrAl3BO7 Nanocrystalline Phosphors for Near-UV LEDs.

Up to now, orchestrating the coexistence of Eu2+ and Eu3+ activators in a single host lattice has been an extremely difficult task, especially for the appearance of the characteristic emission of Eu2+ and Eu3+ in order to generate white light. Nevertheless, here we demonstrate a new Eu2+/Eu3+ coactivated SrAl3BO7 nanocrystalline phosphor with abundant and excellent multichannel luminescence properties. A series of Eu2+/Eu3+ coactivated SrAl3BO7 nanocrystalline phosphors were prepared through a Pechini-type sol-gel method followed by a reduction process. With excitation of UV/NUV light, the prepared SrAl3BO7:Eu2+,Eu3+ phosphors show not only the characteristic f-f transitions of Eu3+ ion (5DJ → 7FJ,J', J, J' = 0-3), but also the 5d → 4f transitions of Eu2+ ion with comparable intensity from 400 to 700 nm in the whole visible spectral region. The luminescence color of the SrAl3BO7:Eu2+,Eu3+ phosphor can be tuned from blue, blue-green, white, and orange to orange-red by changing the excitation wavelength, the overall doping concentration of europium ions (Eu2+, Eu3+), and the relative ratio of Eu2+ to Eu3+ ions to some extent. A single-phase white-light emission has been realized in SrAl3BO7:Eu2+,Eu3+ phosphor. The obtained SrAl3BO7:Eu2+,Eu3+ phosphor has potential application in the area of NUV white-light-emitting diodes.

Well-defined magnetic surface imprinted nanoparticles for selective enrichment of 2,4-dichlorophenoxyacetic acid in real samples.

Superparamagnetic core-shell molecularly imprinted polymer nanoparticles (MIPs) were prepared via surface initiated reversible-addition fragmentation chain transfer (si-RAFT) polymerization for the selective recognition of 2,4-dichlorophenoxyacetic acid (2,4-D) in real samples. The construction of uniform core-shell structure with a 50nm MIP layer was successfully accomplished, which favored mass transfer and resulted in fast recognition kinetics. The static equilibrium experiments revealed the satisfied adsorption capacity and imprinting efficiency of Fe3O4@MIP. Moreover, the Fe3O4@MIP exhibited high selectivity and affinity towards 2,4-D over structural analogues. The prepared Fe3O4@MIP nanoparticles were used for the selective enrichment of 2,4-D in tap water and Chinese cabbage samples. Combined with RP-HPLC, the recoveries of 2,4-D were calculated from 93.1% to 103.3% with RSD of 1.7-5.4% (n = 3) in Chinese cabbage samples. This work provides a versatile approach for fabricating well-constructed core-shell MIP nanoparticles for rapid enrichment and highly selective separation of target molecules in real samples.

Synthesis of molecularly imprinted polymers using acrylamide-ß-cyclodextrin as a cofunctional monomer for the specific capture of tea saponins from the defatted cake extract of Camellia oleifera.

Molecularly imprinted polymers were synthesized using mixed tea saponins as a template and acrylamide-ß-cyclodextrin as a cofunctional monomer for the specific binding and purification of tea saponins from the defatted cake extract of Camellia oleifera. The adsorption properties of the prepared polymers were systematically evaluated including adsorption kinetics, adsorption isotherms, and selective recognition characteristics. It showed that the adsorption kinetics followed the pseudo first-order kinetic model (R2 = 0.995) with an equilibrium time of 3 h, adsorption isotherm data fitted well with the Langmuir-Freundlich model (R2 = 0.984) with an adsorption capacity of 14.23 mg/g. The relative selectivity coefficient (k´) in the presence of the analogues glycyrrhizic acid and glycyrrhetinic acid were 1.16 and 17.21, respectively. The performance of the molecularly imprinted polymers as solid-phase extraction materials was investigated and the results indicated that using acrylamide-ß-cyclodextrin as a cofunctional monomer improved both the adsorption capacity and active sites stability of the imprinted polymers. The solid-phase extraction using the polymers as packing materials was subsequently applied for the separation of tea saponins in raw C. oleifera press extract, and targets were obtained with a purity reaching 89%.

Host-Sensitized and Tunable Luminescence of GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) Nanocrystalline Phosphors with Abundant Color.

Up to now, GdNbO4 has always been regarded as an essentially inert material in the visible region with excitation of UV light and electron beams. Nevertheless, here we demonstrate a new recreating blue emission of GdNbO4 nanocrystalline phosphors with a quantum efficiency of 41.6% and host sensitized luminescence in GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) nanocrystalline phosphors with abundant color in response to UV light and electron beams. The GdNbO4 and GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) nanocrystalline phosphors were synthesized by a Pechini-type sol-gel process. With excitation of UV light and low-voltage electron beams, the obtained GdNbO4 nanocrystalline phosphor presents a strong blue luminescence from 280 to 650 nm centered around 440 nm, and the GdNbO4:Ln3+ nanocrystalline phosphors show both host emission and respective emission lines derived from the characterize f-f transitions of the doping Eu3+, Tb3+, and Tm3+ ions. The luminescence color of GdNbO4:Ln3+ nanocrystalline phosphors can be tuned from blue to green, red, blue-green, orange, pinkish, white, etc. by varying the doping species, concentration, and relative ratio of the codoping rare earth ions in GdNbO4 host lattice. A single-phase white-light-emission has been realized in Eu3+/Tb3+/Tm3+ triply doped GdNbO4 nanocrystalline phosphors. The luminescence properties and mechanisms of GdNbO4 and GdNbO4:Ln3+ (Ln3+ = Eu3+/Tb3+/Tm3+) are updated.

Fluorescence turn-on chemosensor for highly selective and sensitive detection and bioimaging of Al(3+) in living cells based on ion-induced aggregation.

Herein, a new fluorescence turn-on chemosensor 2-(4-(1,2,2-triphenylvinyl)phenoxy)acetic acid (TPE-COOH) specific for Al(3+) was presented by combining the aggregation-induced-emission (AIE) effect of tertaphenylethylene and the complexation capability of carboxyl. The introduction of carboxylic group provides the probe with good water-solubility which is important for analyzing biological samples. The recognition toward Al(3+) induced the molecular aggregation and activated the blue fluorescence of the TPE core. The high selectivity of the probe was demonstrated by discriminating Al(3+) over a variety of metal ions in a complex mixture. A detection limit down to 21.6 nM was determined for Al(3+) quantitation. Furthermore, benefiting from its good water solubility and biocompatibility, imaging detection and real-time monitoring of Al(3+) in living HeLa cells were successfully achieved. The AIE effect of the probe enables high signal-to-noise ratio for bioimaging even without multiple washing steps. These superiorities make this probe a great potential for the functional study and analysis of Al(3+) in complex biosystems.

Catalytic synthesis and antioxidant activity of sulfated polysaccharide from Momordica charantia L.

Sulfated derivatives of polysaccharide from Momordica charantia L. (MCPS) with different degree of sulfation (DS) were synthesized by chlorosulfonic acid method with ionic liquids as solvent. Fourier transform infrared spectra and 13C nuclear magnetic resonance spectra indicated that C-6 substitution was predominant in MCPS compared with the C-2 position. Compared with the native polysaccharide from Momordica charantia L. (MCP), MCPS exhibited more excellent antioxidant activities in vitro, which indicated that sulfated modification could enhance antioxidant activities of MCP. Furthermore, high DS and moderate molecular weight could improve the antioxidant activities of polysaccharide.

[Carbonyl compounds emission and uptake by plant: Research progress].

This paper reviewed the researches on the carbonyl compounds emission and uptake by plants, and discussed the compensation point of the bidirectional exchange of carbonyl compounds between plants and atmosphere. The uptake by leaf stomata and stratum corneum is the principal way for the purification of air aldehydes by plants. After entering into plant leaves, most parts of carbonyl compounds can be metabolized into organic acid, glucide, amino acid, and carbon dioxide, etc. , by the endoenzymes in leaves. The exchange direction of the carbonyl compounds between plants and atmosphere can be preliminarily predicted by the compensation point and the concentrations of ambient carbonyl compounds. This paper summarized the analytical methods such as DNPH/HPLC/UV and PFPH/GC/MS used for the determination of carbonyl compounds emitted from plants or in plant leaves. The main research interests in the future were pointed out, e. g. , to improve and optimize the analytical methods for the determination of carbonyl compounds emitted from plants and the researches on systems (e. g. , plant-soil system), to enlarge the detection species of carbonyl compounds emitted from plants, to screen the plant species which can effectively metabolize the pollutants, and to popularize the phytoremediation techniques for atmospheric

Preparation of graphene/TiO2 composites by nonionic surfactant strategy and their simulated sunlight and visible light photocatalytic activity towards representative aqueous POPs degradation.

A series of graphene/TiO2 composites were fabricated using a single-step nonionic surfactant strategy combined with the solvothermal treatment technique. Their phase structure, morphology, porosity, optical absorption property, as well as composition and structure, were characterized. The as-prepared composites were successfully applied to degrade aqueous persistent organic pollutants (POPs) such as rhodamine B, aldicarb, and norfloxacin in simulated sunlight (λ>320 nm) and visible light (λ>400 nm) irradiation. The degradation mechanism and kinetics of aqueous POPs were studied in detail. The mineralization of aqueous POPs and the recyclability of the composites were also tested in the same condition.

Urine Metabolite Profiling of Human Colorectal Cancer by Capillary Electrophoresis Mass Spectrometry Based on MRB.

Aim. The study was to investigate the metabolic profile of urine metabolites and to elucidate their clinical significance in patients with colorectal cancer. Methods. Colorectal cancers from early stage and advanced stage were used in this study. Urine samples of colorectal cancer patients and healthy adults were collected and subjected to capillary electrophoresis mass spectrometry based on moving reaction boundary analysis. The metabolic data were analyzed by SPSS 17.0 to find urinary biomarkers for colorectal cancer. Results. The results indicated that the urine metabolic profiling of colorectal cancer patients had significant changes compared with the normal controls, and there were also differences between early stage and advanced colorectal cancer patients. Compared with the control group, the levels of isoleucine, valine, arginine, lactate acid and leucine increased (P < 0.05), but those of histidine, methionine, serine, aspartic acid, citric acid, succinate, and malic acid decreased in urine samples from colorectal cancer (P < 0.05). Furthermore, the levels of isoleucine and valine were lower in urine of patients with advanced colorectal cancer than those in early stage colorectal cancer (P < 0.05). Conclusion. The technique of capillary electrophoresis mass spectrometry based on MRB could reveal the significant metabolic alterations during progression of colorectal cancer, and the method is feasible and may be useful for the early diagnosis of colorectal cancer.

Novel molecularly imprinted polymer using 1-(α-methyl acrylate)-3-methylimidazolium bromide as functional monomer for simultaneous extraction and determination of water-soluble acid dyes in wastewater and soft drink by solid phase extraction and high performance liquid chromatography.

Novel water-compatible molecularly imprinted polymers were synthesized in methanol-water systems with Tratarzine as template and 1-(α-methyl acrylate)-3-methylimidazolium bromide (1-MA-3MI-Br) as functional monomer, which has π-π hydrophobic, hydrogen-bonding and electrostatic interactions with template molecule. 1-MA-3MI-Br molecularly imprinted polymers (1-MA-3MI-Br-MIPs) were used as selective sorbents for the solid-phase extraction (SPE) of water-soluble acid dyes from wastewater and soft drink. The good linearity of the method was obtained in a range of 5.0-2000 µg/L with the correlation coefficient of > 0.999. The detection limits were in a range of 0.13-0.51 µg/L for the water-soluble acid dyes in wastewater and 0.095-0.84 µg/L for those in soft drink. The mean recoveries for the acid dyes are from 89.1% to 101.0% in spiked wastewater and 91.0-101.3% in spiked soft drink. Compared with strongly anion exchange solid phase extraction (SAX-SPE), mixture anion exchange solid phase extraction (MAX-SPE), and 1-MA-3MI-Br non-imprinted solid phase extraction (1-MA-3MI-Br-NISPE), almost all of the matrix interferences were removed by 1-MA-3MI-Br-MISPE, exhibiting higher selectivity, recovery and enrichment ability for the acid dyes and better baselines in the results of HPLC analysis.

2-(1,2-Dimethyl-1H-indol-3-yl)-1-{5-[3-(1,3-dioxolan-2-yl)phen-yl]-2-methyl-thio-phen-3-yl}-3,3,4,4,5,5-hexa-fluoro-cyclo-pent-1-ene.

The title compound, C(29)H(23)F(6)NO(2)S, a member of a new family of photochromic diaryl-ethene compounds having an unsymmetrically substituted hexa-fluoro-cyclo-pentene unit, displays dihedral angles between the indole and thio-phene rings of 52.5 (4)°, and between the indole ring and the planar C-C=C-C unit of the cyclopentene ring of 53.8 (6)°. The distance between the potentially reactive C atoms from the two heteroaryl substituents of 3.817 (6) Šis proven to be short enough for photocyclization to occur.

Determination of malachite green in fish water samples by cloud-point extraction coupled to cation-selective exhaustive injection and sweeping-MEKC.

We have employed a high-sensitivity off-line coupled with on-line preconcentration method, cloud-point extraction (CPE)/cation-selective exhaustive injection (CSEI) and sweeping-MEKC, for the analysis of malachite green. The variables that affect CPE were investigated. The optimal conditions were 250 g/L of Triton X-100, 10% of Na(2)SO(4) (w/v), heat-assisted at 60 degrees C for 20 min. We monitored the effects of several of the CSEI-sweeping-MEKC parameters - including the type of BGE, the concentrations of SDS, the injection length of the high-conductivity buffer, and the injection time of the sample - to optimize the separation process. The optimal BGE was 50 mM citric acid (pH 2.2) containing 100 mM SDS. In addition, electrokinetic injection of the sample at 15 kV for 800 s provided both high separation efficiency and enhanced sweeping sensitivity. The sensitivity enhancement for malachite green was 1.9 x 10(4) relative to CZE; the coefficients of determination exceeded 0.9928. The LOD, based on an S/N of 3:1, of CSEI-sweeping-MEKC was 0.87 ng/mL; in contrast, when using off-line CPE/CSEI-sweeping-MEKC the sensitivity increased to 69.6 pg/mL. This proposed method was successfully applied to determine trace amounts of malachite green in fish water samples.

Poly[µ-5-ammonio-isophthalato-aqua-µ-oxalato-dysprosium(III)].

The title complex, [Dy(C(8)H(6)NO(4))(C(2)O(4))(H(2)O)](n), is a dysprosium coordination polymer with mixed anions and was obtained under hydrothermal conditions. In the structure, the oxalate and 5-amino-isophthalate ligands link the dysprosium ions, building up a two-dimensional metal-organic framework parallel to the (10) plane. These sheets are further connected through O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds, forming a three-dimensional supra-molecular structure.

Separation of flavanone enantiomers and flavanone glucoside diastereomers from Balanophora involucrata Hook. f. by capillary electrophoresis and reversed-phase high-performance liquid chromatography on a C18 column.

A pair of flavanone glucoside diastereomers, (2R)- and (2S)-eriodictyol-5-O-beta-d-glucopyranoside (1a, 1b), was successfully separated by RP-C(18) high-performance liquid chromatography from Balanophora involucrata Hook. f. Some other compounds, including a pair of flavanone enantiomers, (2R)- and (2S)-eriodictyol (2a, 2b), and a pair of flavanone glucoside diastereomers, (2R)- and (2S)-eriodictyol-7-O-beta-d-glucopyranoside(3a, 3b), were separated by capillary electrophoresis from the same plant. The absolute configurations at C-2 of 1a and 1b were determined based on their circular dichroism spectra. Enzymatic hydrolysis of 1a and 1b by beta-d-glucosidase afforded (2R)- and (2S)-eriodictyol, respectively, which were used as the authentic standards for co-elution to determine the migration order of the enantiomers, 2a and 2b. We also report the first example of identifying the migration order of 2a and 2b and resolving the separation of 3a and 3b by capillary electrophoresis. In addition, 1a was unambiguously characterized for the first time by NMR spectra.