WO
3
:Eu
3+
powder was prepared by microemulsion method with cetyltrimethyl ammonium bromide (CTAB) as a surfactant. The prepared WO
3
:Eu
3+
samples were wrapped with SiO
2
by a coating method. The ...WO
3
:Eu
3+
@ SiO
2
nanocomposites with the core-shell structure were prepared by controlling tetraethyl orthosilicate (TEOS) content (1, 3, 5 and 7%) and water–alcohol ratio (1:3, 1:1.5, 1:1 and 2:1). The structure, morphology and luminescence properties of the prepared WO
3
:Eu
3+
@ SiO
2
samples were characterized by XRD, SEM, TEM and fluorescence spectra. The results show that the prepared WO
3
:Eu
3+
@SiO
2
nanocomposites are spherical and granular, and the average particle size is below 100 nm. Under the condition of different TEOS contents, the strongest characteristic peak is located at 554 nm in the green light band at the excitation wavelength of 328 nm. Among the different water–alcohol ratio conditions, the prepared WO
3
:Eu
3+
@SiO
2
nanocomposite has the strongest luminescence intensity at the water–alcohol ratio of 1:3, and the excitation wavelength is 328 nm. The excitation spectra measured at 612 nm have prominent characteristic peaks at 362, 394, 422, 465 and 499 nm, which correspond to the transition of
7
F
0
→
5
D
4
,
7
F
0
→
5
L
6
,
7
F
0
→
5
D
3
,
7
F
0
→
5
D
2
and
7
F
0
→
5
D
1
, respectively.
The high hydrophilicity of alginate materials makes delivering a high load of hydrophobic drug difficult. To overcome this drawback, sodium alginate (SA) was modified using octylamine (OA), and then ...kaempferol (KP) was combined with the alginate solution through the hydrophobic interaction between OA and KP. The modified SA/KP (MSA/KP) hydrogel films were ionically cross-linked by immersing in calcium chloride solution. Subsequently, the products were analyzed via Fourier transform infrared spectroscopy, scanning electron microscopy, contact angle test, thermogravimetric analysis, swelling analysis, water vapor transmission, and mechanical property test. Results showed that compared with the SA hydrogel films, the MSA/KP hydrogel films exhibited an interporous structure, good swelling, and mechanical properties. Moreover, the drug release experiments demonstrated that the MSA/KP hydrogel films achieved a KP encapsulation efficiency of 70.4%, with a sustained KP release of up to 80 h. The cell viability experiments demonstrated that the MSA/KP hydrogel films posed no evident cytotoxicity to human umbilical vein endothelial cells.
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•DFT studies were performed for the butterfly-AZO combined with alkaline earth metals.•The butterfly-AZO⋯Ba2+ is a suitable photocontrol catalytic candidate.•Isomerization of ...butterfly-AZOs was mainly controlled by the NN torsion mechanism.•Reactive MD simulations were performed to predict trans→cis ratio of butterfly-AZOs.
It is desirable to research the photoswitchable supramolecular catalysts by theoretical methods. The azobis-(benzo-18-crown-6) ether (butterfly-AZO for short) combined with the alkaline earth metal cations (Mg2+, Ca2+, Sr2+ and Ba2+) investigated by using both density functional theory (DFT) and reactive molecular dynamics (reactive MD) simulations in this article. DFT calculations demonstrated that butterfly-AZO⋯Ba2+ is a suitable photocontrol catalytic candidate and its isomerization is mainly controlled by the NN rotational mechanism. Furthermore, 100 independent reactive MD simulations demonstrated that 100% trans isomers of butterfly-AZO⋯Ba2+ translated to the cis forms, in good agreement with the experimental data of ∼95%.
Using an atomistic molecular dynamics (MD) simulation, we study the volume relaxation behavior of atactic polystyrene and attempt to correlate this macroscopic behavior with certain microscopic ...aspects. To this end, the gyration radius, the dimensionless relative shape anisotropy, the mean-squared displacement, and the non-Gaussian parameter are examined simultaneously. Our result shows that the structures characterized at different length scales change in a self-similar way and these changes are intimately correlated to the translational mobility of atoms. The initial incubation of structural changes at the different scales originates from the restriction of mobility due to the cage effect. The applicability of the MD simulation to the investigation of the bulk properties is discussed.
Three isomers of polyacetylene (
trans-transoid polyacetylene (Tt-PA),
cis-transoid polyacetylene (Ct-PA), and
trans-cisoid polyacetylene (Tc-PA)), as backbones of many conducting molecular wires, in ...contact with a pair of chemically inert electrodes have been investigated theoretically at the HF/6-31G∗ level by considering the interaction of an external electric field (EF). It is found that the external EF modifies both the geometry and electronic structure of the molecular wires. The application of EF may increase the molecular conjugation and the induced dipole moment, while decrease the HOMO–LUMO gap. It may also make the spatial distributions of the frontier molecular orbitals move from a fully delocalized form to a partially localized one depending on the EF strength. Moreover these changes of three isomers show the structural dependence obviously, the longer the conjugation chain is, the stronger the influence of EF.
A new all-solid-state carbonate ion-selective electrode was fabricated via electrochemical and ion-exchange reactions with Ag nanoparticles and Ag2CO3-BaCO3 as ion-to-electron transducer and ...ion-selective layer, respectively. This paper presented the detailed procedures of the construction of the electrode, the applications of the electrode in various experiments, and the corresponding chemical reaction principles involved. The fabricated electrode was characterized by means of scanning electron microscopy（SEM）, energy dispersive spectrometer（EDS）, and electrochemical analyses. The electrode exhibited stable linear responses to carbonate anions（10-5--10-1 mol/L） with average Slope of the curve being -26.56 mV per decade, and showed negligible responses to NO3, SO2-, and Sal- anions. The electrode was further used to measure the concentration of carbonate anions in boiler water. The measured concentration was lower than that determined via titration. Overall, the electrode exhibited the advantages of miniaturized size, robust construction, and compatibility with other equipment and thus could be ideally integrated into various sensor platforms to collect chemical data from industrial heat exchangers.
The structural, energetic and electronic features of asymmetric armchair single-walled carbon nanotube (SWCNT) junctions have been studied by
ab initio calculations at the B3LYP/6-31G
∗//HF/3-21G
∗ ...levels. The junctions are composed of two SWCNTs with different radius, which are connected by a set of 5-membered and 7-membered carbon rings. The results show that the metallic–metallic junction is more energetically favorable if the junction is formed with a hexagon inserted between the pentagon–heptagon (5/7) pair defects in the armchair nanotube. The shift of the spatial distribution of HOMO and LUMO shows that the asymmetric electronic structure of the junction could be used as a molecular rectifier.
A conducting molecular wire, quaterthiophene, has been investigated theoretically at ab initio Hartree–Fock levels by considering the interaction from an external electric field. When the external ...electric field increases, the single bonds become shorter, the double bonds become longer, and the molecular configuration tends to be more planar. All these features make the molecular wire more conjugated. The molecular electronic structure is sensitive to the electric field as well. With increasing the electric field, the HOMO–LUMO gap decreases. Moreover, the spatial distribution of LUMO moves to the high potential end, whereas HOMO to the low potential end.
Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine ...organisms. Therefore, a high- precision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir（OH）x pH electrode is prepared by a one-step electrochemical method in a LiOH solution at the room temperature. A scanning electron microscope （SEM） observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope （56.14-59.52）, fast response, good stability and long fife-span in tested pH buffer solutions. For a sea trial, four pH electrodes and one Ag/AgC1 reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0-40 m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field.
SPG-56 is a newly isolated glycoprotein from sweet potatoes (Zhongshu NO. 1), but its value for suppressing breast cancer progression remains unknown. This study was designed to investigate the ...potential anti-cancer effects of SPG-56, which consists of 2.9% sugar and 97.1% protein. The effects of SPG-56 on the proliferation and apoptosis of breast cancer cells were determined using CCK-8 and Hoechst 33342 assays and flow cytometry, after staining with Annexin V and PI respectively. The activities of SPG-56 against breast cancer were examined using female BALB/c nude mice orthotopically implanted with human breast carcinoma cells of the types MCF-7 and 4T1-Luc. The cellular experiments showed that SPG-56 inhibited proliferation and promoted apoptosis of MCF-7 cells dose- and time-dependently. Oral administration of SPG-56 significantly suppressed the development of MCF-7 tumor cells (P < 0.01) as compared with an untreated group. The serum tumor markers CEA, CA125 and CA153 in a 240 mg/kg/d SPG-56 decreased by 54.8%, 91.8%, and 90.3%, respectively. The experiments further demonstrated that SPG-56 inhibited the metastasis of breast cancer in MCF-7 and 4T1-bearing mice by altering the expression of MMP2, MMP9, VEGF, Occludin and Claudin. It is concluded that SPG-56 may have potential as a novel anti-tumor candidate for breast cancer.
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