Biphasic defective TiO2–x/reduced graphene oxide(RGO) nanocomposites were synthesized by simple hydrothermal reactions. Compared with TiO2–x and commercial P25, TiO2–x/RGO shows much better photocatalytic activity and excellent stability in pollutants degradation, which could be ascribed to Ti3+ centers complexed with RGO and the synergetic effect between the two phases. The study reveals a new route for the synthesis of mixed-phase defective TiO2–x/carbon material nanocomposites for photocatalytic applications.
Carbon quantum dots(CQDs) with a quantum yield of 11% were synthesized via a simple, low-cost and green hydrothermal treatment using dried lemon peel as carbon source. The obtained CQDs showed a strong emission at the wavelength of 505 nm with an optimum excitation of 425 nm. Carmine with maximum absorption wavelength at 508 nm could selectively quench the fluorescence of CQDs. Based on this principle, a fluorescence probe was developed for carmine determination. The quenching mechanism of CQDs was elucidated. A linear relationship was found in the carmine concentration range of 0.20—30.00 mg/L with the detection limit(3σ/k) of 0.16 mg/L. Satisfactory results were achieved when the method was applied for the determination of carmine in soft drinks.
Cr2O3@ZnO hetero-junction hierarchical nanostructures were designed to be enhanced xylene sensing material, and thereinto, flower-like ZnO hierarchical nanostructures were synthesized via a solution-based method, and then Cr2O3 particles were developed on the surface of ZnO petals via a solvothermal method. From the results of XRD patterns, SEM and TEM images, it can be observed that ZnO has a high-quallity crystallinity and Cr2O3 particles scatter uniformly on the suruface of ZnO. The products with different ratios of Cr2O3 were used to fabricate gas sensors, and the result indicates that the hetero-junction structures prompt the response to xylene, and the reason may be attributed to the decrease of main carriers concentration caused by the p-n junction between ZnO(n-type semiconductor) and Cr2O3(p-type semiconductor), as well as the catalytic oxidation effect on methyl groups of the xylene by Cr2O3.
Mg-MOF-74 has adsorption capacity while less research is about its luminescent properties. In this work, the fluorescent properties of Mg-MOF-74 were studied and characterized. The results show that Mg-MOF-74 exhibits excellent fluorescent properties and, most strikingly, selective sensing detection for nitroaromatic compounds(NACs), 2,4,6-trinitrophenol(PA) in particular, making it a promising PA-selective luminescent probe. This work demonstrates the application of MOFs in the detection of NACs with good selectivity.
Chiral organocatalysts of 4-adamantane amide based on L-proline with double hydrogen potential were synthesized and used in asymmetric aldol reactions. The reactions were evaluated in toluene under‒20 °C. A series of aldol products was obtained from moderate to good yields(up to 98%) with excellent diastereoselectivities(up to >99:1) and enantioselectivities(up to >99%). The aldol products in the system were separated by α-cyclodextrin via host-guest interaction and determined by chiral HPLC. The catalyst could be reused up to five times. The 4-substitution position played an important role in diastereoselectivity and enantioselectivity.
A convenient and efficient method was developed for the synthesis of 2,2′-(arylmethylene)bis(3-hydrox- ycyclohex-2-enone) derivatives via the oleylamine-catalyzed tandem Knoevenagel/Michael addition reactions of aromatic aldehydes and cyclohexane-1,3-diones. This transformation proceeded without any metal catalyst in non-toxic solvent at room temperature with high isolated yields. A plausible mechanism for this process was pro-posed.
A new and convenient procedure was developed for the preparation of sulfonamides and sulfonic esters using N-fluorobenzenesulfonimide(NFSI) as a novel phenylsulfonyl group transfer reagent. In this protocol, a broad range of functional groups were tolerated to give the corresponding sulfonamides or sulfonic esters in moderate to excellent yields. The synthetic strategy for sulfonamides formation proceeded efficiently even under base-, metal- and additive-free conditions with the advantages of operational simplicity, mild reaction conditions as well as short reac-tion time.
A comparison synthesis of 1,2,3-triazoles bearing isoxazole ether was developed between conventional and microwave-assisted heating. Single/double 1,2,3-triazoles bearing isoxazole ether were synthesized by click reaction starting from substituted isoxazolyl alkyne compounds and substituted benzyl azide compounds or neopen-tylglycol diazide in the presence of copper(I) that in-situ generated. Herein, the effect of different catalysts on the yield was researched by conventional method, and the optimal catalyst was selected. The structures of all the synthe-sized compounds were confirmed by MS, FTIR, 1H and 13C NMR spectroscopies. Moreover, the crystal structure of 5-{[(1-benzyl-1H-1,2,3-triazol-4-yl)methoxy]methyl}-3-(4-fluorophenyl)isoxazole(2h) was determined.
In the paper, folic acid(FA)-mediated and β-cyclodextrin(β-CD) derivatives functionalized magnetic Fe3O4 nanoparticles(MNPs) were successfully prepared as drug carriers for the targeted delivery and controlled release of water-insoluble anticancer drug. FA-sulfobutyl ether-β-CD-MNPs(FA-SBE-β-CD-MNPs), FA-hydroxypropyl-β-CD-MNPs(FA-HP-β-CD-MNPs) and FA-carboxymethyl-β-CD-MNPs(FA-CM-β-CD-MNPs) were fabricated, and the loading efficiency and relative entrapment rate of curcumin are 12.04 mg/g, 95.56% for FA-SBE-β-CD-MNPs, 9.6 mg/g, 81.63% for FA-HP-β-CD-MNPs and 7.88 mg/g, 85.28% for FA-CM-β-CD-MNPs, respectively. Meanwhile, at pH=5.0, the optimal release rate of curcumin is about 46.07% for FA-SBE-β-CD-MNPs in 5 h. Cellular uptake indicates that curcumin can be selectively transported to targeting site and released from the internalized carriers. The in vitro cytotoxicity reveals that non-toxic FA-SBE-β-CD-MNPs have excellent biocompatibility on HepG2 cells in the tested concentrations. Therefore, FA-SBE-β-CD-MNPs could provide a promising platform for the targeting delivery of water insoluble anti-cancer drugs for different treatment needs of cancer therapy.
The gene(ABK51908) from Acidothermus cellulolyticus encodes a mature protein of 484 residues with a calculated molecular mass of 53.0 kDa. Sequence analysis revealed that the protein had 59% identity to the β-glucosidases CAA82733, which belongs to glycoside hydrolase family 1(GH1). We cloned and expressed the gene in Escherichia coli BL21-Gold(DE3). The recombinant protein(AcBg) had an optimal pH and temperature of 7.0 and 70 °C, respectively. The specific activities of AcBg under optimal conditions were 290 and 33 U/mg for p-nitrophenyl-β-D-glucopyranoside(pNPG) and cellobiose, respectively. AcBg hydrolyzed the oligosaccharide sequentially from the non-reducing end to produce glucose units according to the results of HPLC analysis. AcBg showed high salt tolerance and monosaccharide-stimulation properties. Its activity rose more than 2-fold when 5 mol/L NaCl/KCl were added. The activity of the β-glucosidase was remarkably enhanced in the presence of 0.2 mol/L D-glucose(increased more than 1.9-fold), 0.1 mol/L α-methyl-D-glucose(increased more than 1.4-fold) and 1.0 mol/L D-xylose(increased more than 1.9-fold). The catalysis kinetics and structural changes in various concentrations of glucose were determined. The results indicate that glucose reduces substrate affinity and causes conformational changes.
In this paper, we synthesized a series of proteolysis targeting chimeras(PROTACs) using VHL E3 ligase ligands for BRD4 protein degradation. One of the most promising compound 19g exhibited robust potency of BRD4 inhibition with IC50 value of (18.6±1.3) nmol/L, respectively. Furthermore, compound 19g potently inhibited cell proliferation in BRD4-sensitive cell lines RS4;11 with IC50 value of (34.2±4.3) nmol/L and capable of inducing de-gradation of BRD4 protein at 0.4—0.6 μmol/L in the RS4;11 leukemia cells. These data show that compound 19g is a highly potent and efficacious BRD4 degrader.
In this paper, antibody-modified silica nanoparticles were successfully synthesized, and their average di-ameter was (109±9) nm. These particles were mixed with cell extracts to target a protein, then, an antibody labeled with fluorescein isothiocyanate(FITC) was added to form FITC-labeled nanoparticle complexes and the product was analyzed using flow cytometry. The results confirm that the intracellular proteins and biomarkers were precisely and sensitivity detected by the novel method in vitro. The FITC intensity of Akt antibody-conjugated particles was in-creased ≥10-fold compared with that of control samples in MCF-7 cells. Furthermore, it can also simultaneously measure several proteins when modified with different antibodies.
The equilibrium structures, formation energy, mechanical properties and electronic properties of Co-Sn intermetallics have been systemically studied by first-principles study. The results show that the CoSn phase is more thermodynamically stable than any other stoichiometry of Co-Sn intermetallics. With the increasing of Co content in Co-Sn intermetallics, the mechanical properties change into brittle behavior from ductility character. Adding proper amount of Co to Co-Sn intermetallics can improve the cycle performance for lithium ion battery anode. However, high Co content will lead to a poor cycle performance for Co-Sn intermetallics.
Among the 3352 isolated pentagon rule(IPR) isomers and 129073 non-IPR isomers satisfying adjacent pentagon pairs(APPs)≤2 of fullerene C112, the lowest-energy IPR and non-IPR isomers of C112 and C112 6- have been fully screened by the density functional tight-binding(DFTB) and density functional theory(DFT) methods for studying the electronic and spectroscopic properties of La2@C112. The structural features and infrared and absorption spectra of those isomers were analyzed in detail, and the characteristic fingerprint absorption peaks were assigned. To clarify the relative stabilities of La2@C112 isomers at high temperature, entropy contributions were determined at the B3LYP level. IPR isomer La2@C112(C 2:860136) is not the lowest-energy isomer but is one of the most important isomers. This is the first work that considers non-IPR C112 isomers when exploring the structure and properties of La2@C112.
A series of fluorine modified TAPO-5 molecular sieves was synthesized by one-pot method using ammo-nium hexafluorotitanate as titanium and fluorine sources. The XPS and DRS UV-Vis results indicated that the exis-tence of F could promote the formation of tetrahedrally coordinated framework Ti and Al, meanwhile, inhibit the formation of anatase TiO2 in TAPO-5 sieves due to the unique role of F in the sol-gel process of metal ions. Further-more, TG, contact angle test, Py-FTIR and 27Al MAS NMR results revealed that fluorine modification increased the surface hydrophobicity and the Lewis acidity of Ti active sites through forming Al xF y units in the neighborhood. All these factors make these fluorine modified TAPO-5 sieves exhibit good catalytic performance in the ammoximation of cyclohexanone.
Two novel energetic alkalic metal salts of 3,6-bis(1H-1,2,3,4-tetrazol-5-yl-amino)-1,2,4,5-tetrazine (BTATz), Li2(BTATz)·6H2O(compound 1) and Na2(BTATz)·2H2O(compound 2), have been synthesized by the reac-tion of BTATz with lithium hydroxide or sodium hydroxide in dimethylsulfoxide(DMSO) solution, respectively, and their structures were characterized by means of elemental analysis and Fourier transform infrared spectrometry(FTIR). Moreover, the single-crystal structure of compound 1 was determined by single crystal X-ray diffraction. It crystal-lizes in the monoclinic space group P1/c. Furthermore, their thermal decomposition behaviors were investigated by means of differential scanning calorimetry(DSC) and thermogravimetry-differential thermal gravimetry(TG-DTG). The results show that the exothermic decomposition peak temperatures for compounds 1 and 2 were 642.65 and 644.46 K, respectively, and the kinetic equations of the main exothermic decomposition were also derived from non-isothermal method. Additionally, the thermal safety of the two compounds was evaluated by calculating self-accelerating decomposition temperature(T SADT) and critical temperature of thermal explosion(T b). The results(the TSADT and T b values are 605.43 and 635.69 K for compound 1; 607.38 and 638.96 K for compound 2) reveal that the two compounds exhibit better thermal safety than BTATz.
A simple and efficient colorimetric biosensing for hydrogen peroxide and glucose with peroxidase-like vitamin C(Vc) functionalized Fe3O4 magnetic nanoparticles(VcFe3O4 MNPs) as a catalyst is reported. Compared with Fe3O4 MNPs and other catalysts, VcFe3O4 MNPs exhibited superior catalytic properties. Kinetic studies indicated that vitamin C incorporated on Fe3O4 MNPs improved the affinity toward H2O2. As low as 0.29 μmol/L H2O2 can be detected with a wide linear range of 0.5―100 μmol/L H2O2; moreover, as low as 0.288 μmol/L glucose can be detected with a linear range of 0.5―25 μmol/L glucose. The detection method was highly sensitive in sensing H2O2 and glucose. The robustness of VcFe3O4 MNPs rendered them suitable for wide ranging applications.
We established a novel strategy for the synthesis of reduced graphene oxide(rGO)@TiO2 nanotube hybrids using an 18 W UV-assisted photo-catalytic reduction method for utilization as photo-anode of dye-sensitized solar cells(DSSCs). The photo-conversion efficiency of DSSCs was significantly enhanced after the addition of rGO, and in addition, the photo-anode showed decreased internal resistance. Analysis of rGO@TiO2 hybrids by transmissions scanning electron microscopy(TEM), X-ray diffraction(XRD), Raman spectra, N2 adsorption and desorption, atomic force microscopy(AFM) and X-ray photoelectron spectroscopy(XPS) demonstrates that the rGO modified TiO2 nanotubes can increase the short-circuit current and the conversion efficiency of dye-sensitized solar cells. The efficiency is improved by almost two folds as much compared to those of the bare TiO2 nanotubes.
C-doped Nb2O5 with abundant mesopores has been successfully synthesized through a facile solvothermal synthetic strategy followed by calcination treatment. The resulting C-doped Nb2O5 displayed the highest BET surface area(345 m2/g) and large mesopore size(ca. 4.2 nm), capable of offering more accessible active sites as well as faster mass transfer for catalysis. Besides, the doping of C(2.21%, molar fraction) at the O sites in Nb2O5 lattice greatly enhanced visible-light response by lowering the band gap, thereby making the material a photocatalyst under visible-light irradiation. Typically, the C-doped Nb2O5 exhibited a high H2 evolution rate of ca. 39.10 μmol·g–1·h–1 and also degraded RhB dye completely after 30 min of visible light exposure, which turned out to be much better than Degussa P25 and pure Nb2O5 catalysts.
Various imidazolium and choline-based functional ionic liquids(ILs) comprising different cations and anions were grafted onto Burkholderiacepacia lipase(BCL) through surface amino acids coupling. The catalytic ac-tivity, thermostability, organic solvent tolerance and adaptability to temperature and pH changes of the modified BCL were then evaluated in olive oil hydrolysis reaction. The results showed that different combinations of cations and anions in ILs had important influence on the catalytic performance of the modified lipases. BCL modified with IL [Choline][H2PO4] was the most improved lipase, in which increases by 1.2 folds in relative activity, 2.5 folds in typi-cal proton solvent(10% methanol, volume fraction), and 1.4 folds in thermostability(after incubation at 70 °C for 2 h) were achieved in relative toits native form. BCL modified with [HOOCEPEG350IM][BF4] had higher optimal tempe- rature and pH, and better thermosability compared with the native and other modified BCLs. The conformational changes of BCLs were also confirmed by fluorescence spectroscopy and circular dichroism spectroscopy.
PtCo x bimetallic nanoparticles(NPs) supported on tannin-grafted collagen fiber(CF-BT) have been pre-pared via a novel synthetic strategy, and applied for catalytic hydrogenation of cinnamaldehyde(CAL), a typic unsa-turated aldehyde. The catalysts were systematically and specifically characterized by means of XRD, XPS, TEM-EDX and SEM to clarify the structure-property correlation. It was found that the PtCo x/CF-BT catalysts exhi-bited significantly enhanced catalytic activity and desirable stability in catalytic hydrogenation of CAL, which is ascribed to the synergistic interaction between bimetallic components, the effective dispersion, the anchoring role of CF-BT matrix on bimetallic NPs, as well as the lower mass transfer resistance of the matrix.
The C3N4/Ag composite nanosheets were facilely prepared via an in situ reduction process and Ag nanoparticles were well dispersed on the surface of C3N4 nanosheets. The unique two-dimensional structure and strong interactions between C3N4 nanosheets and Ag nanoparticles contributed the good surface-enhanced Raman scattering(SERS) property due to the electromagnetic field enhancement. In addition, the as-prepared C3N4/Ag composite nanosheets could be used as catalysts or photocatalyst for the degradation of methylene blue(MB) in the presence of NaBH4 or under visible light. Therefore, a facile SERS monitoring of the catalytic and photocatalytic degradation process of MB and the determination of the reaction kinetics were developed.
A Ni/TiO2(TBT) catalyst was prepared through in situ precipitation, using tetrabutyl titanate(TBT) as the TiO2 precursor, and was studied in CO methanation. A Ni catalyst supported on commercial TiO2 was also prepared through post precipitation and studied to compare the influence of Ni precipitation conditions on the catalyst’s performance. To gain insight on their structure and physicochemical properties, the catalysts were characterized with N2-adsorption, X-ray diffraction, transimission electron microscopy, H2 temperature programmed reduction and temperature programmed desorption. The results showed that the in situ precipitation method was beneficial to the dispersion of Ni and the formation of more active sites on the Ni/TiO2 catalyst. In addition, the density of the metal- support boundary and its interaction with the active component were also increased. These characteristics of Ni/TiO2(TBT) led to a lower light-off temperature and a suppression of Ni sintering during CO methanation. As a consequence, the Ni/TiO2(TBT) exhibited better catalytic behavior, with a CO conversion of 99.4% and CH4 selectiv-ity of 90.4% under the following conditions: p=1 MPa, t=320 °C, n(H2)/n(CO)=3, gas hour space velocity (GHSV)=2×104 mL·g–1·h–1. The life test results of the two catalysts showed that Ni/TiO2(TBT) was more stable and the catalytic activity remained at its initial level after being used for 30 h.
The removal of cadmium(Cd) from synthetic solutions by batch adsorption process was performed using eggshell powder, which is mainly composed of calcite(CaCO3). In order to optimize the adsorption process, a re-sponse surface methodology(RSM) based on Central Composite Design(CCD) was applied. Developed model for Cd remo- val yields(R, %) response was statistically validated by variance analysis(ANOVA) which showed a high de-termination coefficient value(R 2=0.9889). According to Minitab software, the optimal conditions were found at tem-perature of 44 °C, eggshell adsorbent dose of 2.98 g, initial Cd concentration of 36.74 mg/L and initial pH of 7. Un-der these conditions, the Cd removal yield was 98.76%. The deviation value of 1.24% confirms the validity of the model for the adsorption process optimization. The adsorption isotherm has been described by a Freundlich model. In addition, the predominant sorption mechanisms are the chemisorptions or precipitation(non-reversible) and ion ex-change(reversible).
Using polyethylene glycol(PEG) or glycerol as the plasticizer, we synthesized the hydrogels from poly(ethylene glycol) diacrylate(PEGDA), polyvinylpyrrolidone(PVP) and poly(vinyl alcohol)(PVA) under UV radiation. The effects of different plasticizers on the mechanical properties and adhesion properties of the hydrogels were investigated. The results show that the plasticizer can improve the elongation and peeling force. The most pronounced changes in the tensile property of the hydrogels are due to the addition of glycerol followed by PEG, the lower the plasticizer’s molecular weight, the greater its effect. The maximum peeling force is 0.317 or 0.257 N with PEG or glycerol as plasticizer, respectively, and their adhesion properties are due to the formation of hydrogen bonds.
Using the hydrogen-bonding interaction between graphene oxide(GO) and sulfonated polyethersulfone (SPES), we constructed the multilayer structure of GO and SPES on the polyester fiber mats via layer-by-layer self-assembly. In each self-assembled layer, sulfonic acid groups are arranged along the axis of fiber, which provides the long-range proton transmission channels, promoting the rapidly proton conduction. The performances of the composite membranes based on SPES and multilayer assembled polyester fiber mats were studied. The results show that the proton conductivity of composite membranes increases with the increasing assembly layers. At the same time, the mechanical properties and methanol-resistance of the composite membranes were obviously improved.
An oligo-fluoropolymer(PFM) with functional cycloaliphatic epoxy and fluorinated groups was obtained via free radical polymerization and applied to the modification of cycloaliphatic epoxy resins(CE). The chemical structure of PFM was characterized by Fourier transform infrared(FTIR) spectroscopy, gel permeation chromatogra-phy(GPC) and nuclear magnetic resonance(NMR) spectroscopy, and the effects of different PFM concentra-tions(0.5%—6%, mass fraction) on the thermal resistance, mechanical properties, surface dewettability, light trans-mission, refractive index and various cured polymer properties were studied in detail. The DSC and TGA results demonstrate that the modified epoxy resins possess a higher thermal resistance than the neat epoxy resin. The im-provements in the surface dewettability and water resistance are caused by the high crosslinking density and the enrichment of the oligo-fluorinated random copolymers dispersed in the matrix. The fracture surface morphologies of the thermosets were investigated by scanning electron microscopy(SEM) and transmission electron microsco-py(TEM). It was observed that the optical transmittance of the composites was maintained even though microphase separation occurred during the curing process. With respect to the corresponding properties of the neat epoxy resins, the 2 phr(parts per hundreds of resin) PFM thermoset exhibited relatively better comprehensive properties, making the cured material a good candidate for light-emitting diode(LED) encapsulation.