期刊导航

Totally found 3890 items.

  • [期刊] The green one-step electrodeposition of oxygen-functionalized porous g-C3N4 decorated with Fe3O4 nanoparticles onto Ni-foam as a binder-free outstanding material for supercapacitors
    In this study, the binder-free high-performance nanocomposite of Fe3O4/oxygen-functionalized g-C3N4 was fabricated through a one-pot electrophoretic-electrochemical (EP-EC) process. In this process, Fe3O4 nanoparticles were in situ nucleated through a two-step electrochemical-chemical (EC) mechanism on oxygen-functionalized g-C3N4 (O-g-C3N4) sheets electrophoretically embedded on a Ni-foam support. Also, pristine Fe3O4 nanoparticles and O-g-C3N4 sheets were fabricated on Ni foam (i.e. Fe3O4/Ni foam and O-g-C3N4/Ni foam) via the EC and EP processes, respectively. The prepared powders/electrodes were fully characterized through XRD, FT-IR, BET/BJH, Raman spectroscopy, TGA/DSC, FE-SEM and TEM. The morphological observations confirmed the nucleation and growth of Fe3O4 particles on the porous O-g-C3N4 sheets in the structure of the Fe3O4@O-g-C3N4/Ni foam electrode. The formation mechanisms of the pristine Fe3O4 particles, pristine O-g-C3N4 sheets and their nanocomposite on the Ni-foam support were explained based on the electrophoretic-electrochemical deposition processes. Electrochemical evaluation by galvanostatic charge-discharge (GCD) indicated that the fabricated Fe3O4@O-g-C3N4/Ni foam delivered a specific capacitance of 710 F g(-1) at 0.5 A g(-1) and capacity retention of 94.6% and 80.15% after 8000 GCD cycling at the current load of 0.5 and 3 A g(-1), whereas the pristine Fe3O4/NF showed a specific capacitance of 277 F g(-1) at 0.5 A g(-1) and capacity retentions of 82.4% and 48.9% only, under similar GCD conditions, respectively. These findings prove the superior synergism between the Fe3O4 nanoparticles and oxygen-functionalized g-C3N4 sheets in the composite structure.
  • [期刊] Extraction of phenylurea herbicides from rice and environmental water utilizing MIL-100(Fe)-functionalized magnetic adsorbents
    In this paper, a novel method is reported for the extraction and enrichment of phenylurea herbicides (PUHs) from rice and environmental water samples using MIL-100(Fe)-functionalized magnetic nanoparticles as adsorbents. Fe3O4@MIL-100(Fe) magnetic nanoparticles (MNPs) were prepared via self-assembly of MIL-100(Fe) NPs on the Fe3O4 surface modified by thioglycolic acid. The prepared Fe3O4@MIL-100(Fe) NPs displayed porosity, a conjugated structure and strong hydrogen bonding ability, which promoted high adsorption toward PUHs. We also showed that Fe3O4@MIL-100(Fe) NPs could adsorb and extract PUHs from environmental water and rice samples. After desorption using acetonitrile, PUH concentration was determined by a high performance liquid chromatography-diode array detector (HPLC-DAD). The limits of detection (S/N = 3) were 0.037-0.166 ng mL-1 in environmental water samples and 0.127-0.254 ng g-1 in rice samples. The determination coefficients (R2) were in the range of 0.9986-0.9993. The results indicate that the synthesized Fe3O4@MIL-100 (Fe) NPs are stable and effective adsorbents for the magnetic solid phase extraction (MSPE) of PUHs.
  • [期刊] Red-emissive nitrogen doped carbon quantum dots for highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples
    Red-emissive nitrogen doped carbon quantum dots (N-CQDs) were synthesized by a facile and efficient microwave-assisted hydrothermal treatment of p-phenylenediamine (p-PD), and then applied for the highly selective and sensitive fluorescence detection of the alachlor herbicide in soil samples. The synthesized N-CQDs exhibited strong red emission with a 27.6% quantum yield (QY) and high stability. Under the optimized experimental conditions, the as-prepared red-emissive N-CQDs were employed as a fluorescent probe to successfully detect trace alachlor, and their fluorescence presented a good linear decline with the increase of the alachlor concentration from 0.005 to 150 mu M with a limit of detection of 0.2 nM. The N-CQDs as a fluorescent probe were used for the detection of alachlor in soil samples with satisfactory recoveries ranging from 86.6-114.3%, indicating that they were a promising fluorescent probe for highly selective and sensitive determination of alachlor. References:
  • [期刊] Extraction of phenylurea herbicides from rice and environmental water utilizing MIL-100(Fe)-functionalized magnetic adsorbents (Electronic supplementary information (ESI) available: Instrument section and supplementary figures. See DOI: 10.1039/c9nj05553c)
    In this paper, a novel method is reported for the extraction and enrichment of phenylurea herbicides (PUHs) from rice and environmental water samples using MIL-100(Fe)-functionalized magnetic nanoparticles as adsorbents. Fe3O4@MIL-100(Fe) magnetic nanoparticles (MNPs) were prepared via self-assembly of MIL-100(Fe) NPs on the Fe3O4 surface modified by thioglycolic acid. The prepared Fe3O4@MIL-100(Fe) NPs displayed porosity, a conjugated structure and strong hydrogen bonding ability, which promoted high adsorption toward PUHs. We also showed that Fe3O4@MIL-100(Fe) NPs could adsorb and extract PUHs from environmental water and rice samples. After desorption using acetonitrile, PUH concentration was determined by a high performance liquid chromatography-diode array detector (HPLC-DAD). The limits of detection (S/N = 3) were 0.037–0.166 ng mL−1 in environmental water samples and 0.127–0.254 ng g−1 in rice samples. The determination coefficients (R2) were in the range of 0.9986–0.9993. The results indicate that the synthesized Fe3O4@MIL-100 (Fe) NPs are stable and effective adsorbents for the magnetic solid phase extraction (MSPE) of PUHs.
  • [期刊] Unraveling the helianane family: a complementary quantum mechanical study
    The skeleton of the helianane's family is an unsolved controversial topic. Recent synthetic studies and C-13 NMR structural analysis have demanded for an amendment of helianane to the open ring curcudiol. However, some authors argue that the original helianane structure, a benzofused eight-membered ether ring system, cannot be ruled out immediately without further spectral analyses of curcudiol and helianane. The fact that this compound is extremely rare, obtained only from marine organisms, makes remote the possibility of reisolation. Therefore, we decided to approach this problem computationally. Herein, we performed a complementary quantum mechanical study in order to provide more information about the helianane's actual skeleton. Our C-13 NMR chemical shifts calculations suggests that the curcudiol structure is more likely to be the correct one. In addition, we simulated the formation pathways for both products starting from the known biosynthetic precursor. The results show that curcudiol is around 8.0 kcal mol(-1) more stable than the originally proposed helianane structure.
  • [期刊] Synthesis and characterization of a quaternary copolymer retarder for cementing in a long sealing section with large temperature difference
    Because of the contradiction between the safe thickening time of cement slurry and over-retarding at the top in the cementing of a long sealing section with large temperature difference, we synthesized a quaternary copolymerization retarder with 2-acrylamide-2-methyl propane sulfonic acid (AMPS), acrylic acid (AA), diallyl dimethyl ammonium chloride (DMDAAC) and allyl polyoxyethylene ether (APEG). The structure of the retarder was characterized by FTIR and H-1 NMR and its thermal stability was tested by TG-DSC. The results showed that the molecule contained the designed functional groups, the initial pyrolysis temperature was 364 degrees C, and its performance was stable in the temperature range of 90-150 degrees C. There was no "bulge" or "step" on the thickening curve, and the thickening time could meet the safety requirements of pumping at high temperatures. It can also ensure the development of compressive strength of cement in the low-temperature section and has excellent temperature adaptability. Through the study of its retardation mechanism, it was found that the retarder molecules formed an adsorption layer of a certain thickness on the surface of cement particles by adsorption, and the concentration of Ca2+ in the solution was reduced by complexation, so as to prevent cement hydration and prolong the thickening time. Generally speaking, the large temperature difference adaptability of retarders was mainly manifested in the decrease of molecular adsorption capacity and performance at low-temperature and the improvement of molecular adsorption capacity and performance at high-temperature.
  • [期刊] Synthesis of an amino phosphinodiselenoic acid ester and beta-amino diselenides employing P2Se5
    The synthesis of a new class of amino phosphinodiselenoic acid ester and beta-amino diselenides is conducted by employing a reaction between N-beta-protected aminoalkyl iodide and phosphorus pentaselenide (P2Se5) has been described. In the presence of protic solvents, amino phosphinodiselenoic acid esters were found to be the major products, whereas beta-amino diselenides were formed exclusively when the reaction was carried out in polar aprotic solvents.
  • [期刊] Chromogenic agents built around a multifunctional double-triazine framework for enzymatically triggered cross-linking under physiological conditions
    An "A(2)BC"-type bioconjugatable compound (1) that enables enzymatically triggered cross-linking chemistry has been designed and synthesized. The compound contains two indoxyl-glucoside units (A units), which upon action of a glucosidase undergo oxidative dimerization to form a water-insoluble indigoid dye. The other two moieties are azide (B, for click chemistry) and (C) a triazine-chloride or a coumarin dye; the former enables substitution with a nucleophile while the latter provides for ratiometric sensing of the extent of indigoid dye formation. A 7-component building block synthesis relies on successive substitution of 2 cyanuric chloride (2,4,6-trichloro-1,3,5-triazine) molecules with 5 other constituents (2A, B, C, and a piperazine-sulfobetaine moiety); the latter bear oligoethylene glycol (i.e., PEG) or aminoalkyl tethers. The substitution reactions of cyanuric chloride proceed almost entirely at room temperature with control achieved by the order of nucleophile reactivity (aliphatic amine > phenol >> aliphatic alcohol) and the nature of a chosen base. Treatment of 1 with glucosidase under physiological conditions in aqueous solution gave an indigoid solution and a precipitate (similar to 1 : 9 ratio) that were characterized by absorption spectrometry (including multicomponent analysis), dynamic light-scattering spectroscopy, and optical microscopy. Ratiometric absorption of the integral coumarin dye with the indigoid scaffold showed a low yield (3%) of oligomerization, which suggests future molecular designs might employ longer linkers and/or substituents with greater water solubility.
  • [期刊] Development of nanofibrous scaffolds by varying the TiO2 content in crosslinked PVA for bone tissue engineering
    The use of ceramic and metal nanoparticles is widely being proven as a preferred candidate for tissue engineering owing to their excellent properties such as their high penetration ability and high surface area with tuneable surface properties. In view of this, the effect of bioinert TiO2 incorporation into the polymer matrix is studied in the present study. Crosslinked poly(vinyl alcohol) (PVA) was used as the main polymer base and different weight percentages of TiO2 (0.1 to 0.3 g) were incorporated into the crosslinked PVA matrix by varying the ratio of PVA : TiO2. Nanofibrous scaffolds were then fabricated using the electrospinning technique. The physicochemical properties of the developed nanofibrous scaffolds were analysed systematically. Scanning electron microscopy images demonstrated the good interconnected porous structure with uniform fibres in the range of several hundreds of nanometres. The effect of TiO2 incorporation was observed in terms of an increase in the hydrophilicity of the scaffolds required for cellular infiltration. The mechanical characterization of the developed scaffolds demonstrated an improved mechanical strength for a reduced amount of TiO2 incorporated scaffolds. The degradation study revealed the slow rate of degradation with an increase in the TiO2 content in the PVA matrix of the scaffolds. Cell viability was studied using MG-63 bone osteosarcoma cells for 24, 48, 72 and 96 h, wherein the PT1 scaffold with a content of 0.1 g of TiO2 exhibited the highest cell proliferation of 99.2%. The results thus clearly show that the TiO2 incorporated PVA scaffolds could be potential candidates for bone tissue engineering.
  • [期刊] A solvent- and catalyst-free tandem reaction: synthesis, and photophysical and biological applications of isoindoloquinazolinones
    An easy green synthetic approach for fused isoindoloquinazolinones has been developed under neat reaction (yields up to 91%) conditions. This new one-pot tandem methodology involves condensation of readily available anthranilamide with 3-(2-formylcycloalkenyl)-acrylic ester under solvent- and catalyst-free conditions. This strategy avoids the use of oxidant, and heavy metal catalysts and also is free from work-up and generation of toxic by-products. A dramatic change of photophysical properties of dihydroisoindoloquinazolinones in basic and aqueous media has also been documented in our study. Moreover, our model synthetic compound shows cytotoxic activity towards metastatic HepG2 and PC3 cancer cell lines.
意见反馈
返回顶部