Search

Directional motion in response to specific signals is critically important for micro/nanomotors in precise cargo transport, obstacle avoidance, collective control, and complex maneuvers. In this work, a kind of isotropic light-driven micromotor that is made of hedgehog-shaped TiO2 and functional multiwall carbon nanotubes (Hs-TiO2@FCNTs) has been developed. The FCNTs are closely entangled with Hs-TiO2 and form a close-knit matrix on the surface of Hs-TiO2, which facilitates the transfer of electrons from Hs-TiO2 to FCNTs. Due to the high redox potential of Hs-TiO2, excellent electron-hole separation efficiency by the addition of FCNTs, and isotropic morphology of the micromotor, these Hs-TiO2@FCNT micromotors show phototactic and fuel-free propulsion under unidirectional irradiation of UV light. It is the first time to demonstrate isotropic micromotors that are propelled by self-electrophoresis. The isotropy of Hs-TiO2@FCNT micromotors makes them immune to the rotational Brownian diffusion and local flows, exhibiting superior directionality. The motion direction of our micromotors can be precisely tuned by light and a velocity of 8.9 μm/s is achieved under 160 mW/cm2 UV light illumination. Photodegradation of methylene blue and active transportation of polystyrene beads are demonstrated for a proof-of-concept application of our micromotors. The isotropic design of the Hs-TiO2@FCNT micromotors with enhanced photocatalytic properties unfolds a new paradigm for addressing the limitations of directionality control and chemical fuels in the current asymmetric light-driven micromotors.

Background Exposure to ambient air-borne fine particulate matter (PM2.5) increases respiratory morbidity and mortality. The mechanisms underlying PM2.5-induced adverse effects remain unclear. This study aimed to uncover the molecular mechanisms of PM2.5-induced lung toxicity using a mouse model. Methods Scanning electron microscopy and inductively coupled plasma mass spectrometry were used to examine and analyze PM2.5 morphology and element compositions, respectively. Twenty four male mice were randomly divided into three groups: control (PBS), PM2.5 (4.0 mg/kg b.w.), and PM2.5 + Z-YVAD-FMK. In the latter group, the pan-caspase inhibitor (Z-YVAD-FMK) was intraperitoneally injected into mice at a dose of 12.5 mg/kg body weight prior to intratracheal instillation of PM2.5 (4.0 mg/kg b.w.) every other day for a total of 3 times (n = 8 in each group). Bronchoalveolar lavage fluids (BALFs) were collected 24 h after the last instillation of PM2.5. Levels of total proteins (TP), lactate dehydrogenase (LDH), IL-1β and IL-18 were analyzed for biomarkers of cell injury and inflammation. Additionally, histological alterations of lung tissues were assessed by hematoxylin-eosin staining. mRNA and protein expression of Caspase1, NLRP3 and GSDMD were examined by real-time fluorescent quantitative PCR and immunohistochemical staining. Results Exposure to PM2.5 increased levels of TP, LDH, IL-1β, IL-18 and inflammatory cell counts in lung. The mRNA and protein expression of Caspase1, NLRP3 and GSDMD were increased. Inhibition of the NALRP3/Caspase-1 signaling pathway ameliorated PM2.5-induced lung injury and inflammation, partially through suppressing pyroptosis in lung. Conclusion PM2.5 exposure induces lung injury and inflammation, which is mediated by the NALRP3/Caspase-1 signaling pathway.

The substitutional solid solutions composed of group VA-VIA nonmetallic elements has attracted considerable scientific interest since they provide a pressure-induced route to search for novel types of solid solutions with potential applications. Yet, the pressure-induced solid solution phase is unprecedented in the sulfide family. In this paper, the structural behavior of antimony trisulfide, Sb2S3, has been investigated in order to testify whether or not it can also be driven into the substitutional solid solution phase by high pressures. The experiments were carried out by using a diamond anvil cell and angle dispersive synchrotron X-ray diffraction up to 50.2 GPa at room temperature. The experimental results indicate that Sb2S3 undergoes a series of phase transitions at 5.0, 12.6, 16.9, 21.3, and 28.2 GPa, and develops ultimately into an Sb-S substitutional solid solution, which adopts a body-centered cubic disordered structure. In this structure, the Sb and S atoms are distributed randomly on the bcc lattice sites with space group Im-3m. The structural behavior of Sb2S3 is tentatively assigned by comparison within the A2B3 (A = Sb, Bi; B = Se, Te, S) series under high pressures.

Among the regenerated cellulosic fibers, viscose fiber is the most harmless material on human skin. Nonetheless, viscose fiber has some disadvantages such as low wet strength, high elongation, flammability, and poor color fastness. To improve adsorption and color fastness properties of viscose fiber, amphoteric viscose fibers were prepared. In the current study, viscose fiber was modified with 2,3-epoxy propyltrimethyl ammonium chloride and sodium chloroacetate using sodium hydroxide as catalyst. With adsorption performance of methyl orange and methylene blue as target dyes, the modification conditions were optimized in terms of temperature, time, and catalyst dosage with orthogonal test and single-factor experiment. The modified product was characterized using Fourier transform infrared spectrometry, scanning electron microscopy, ultraviolet spectrophotometry. Meanwhile, nitrogen content, degree of substitution, tensile strength, and adsorption property were measured. It was concluded that the best cationic reaction process conditions were reaction temperature of 70 °C, reaction time of 1 h, and sodium hydroxide dosage of 0.09 g, which was 1% of the amount of viscose fiber when the amount of etherifying agent was 30% of viscose fiber. The best anionic reaction conditions were reaction temperature of 70 °C, reaction time of 1 h, and 3.3 g of 10% sodium hydroxide solution. The adsorption properties of amphoteric modified viscose fiber towards methylene blue and methyl orange were excellent. The maximum adsorption of methylene blue and methyl orange was obtained at 1.483 and 0.234 mg g−1, respectively.

Electrochemical determination of luteolin and baicalein always needs acidic supporting electrolyte to guarantee good sensitivity. Therefore, most of the reported electrochemical sensors of luteolin and baicalein are unsuitable for detection of neutral actual samples. It is necessary to design a highly sensitive sensor for direct determination of them in neutral conditions. In this study, poly(N-isopropylacrylamide-acrylic acid) hydrogel particles (NIPA/AA) and multiwall carbon nanotubes (MWCNTs) composite modified glassy carbon electrode (GCE) was fabricated by a simple casting method. The voltammetric results showed that the NIPA/AA particle film provided acidic environment for proton-electron coupled reaction in neutral mediums. The near-surface pH of the electrode was related on the loaded amount of the NIPA/AA particles in pH range from 4.2 to 5.9. The voltammetric behaviors of luteolin and baicalein at the NIPA/AA-MWCNTs-GCE were studied by cyclic voltammetry. The peak separations between cathodic and anodic peaks were decreased and peak currents were increased because of decrease in pH and increase in ion conductivity at the local electrode surface. The sensitivity of the electrode was investigated by differential pulse voltammetry. Even under neutral conditions, the plots of the oxidation currents of luteolin and baicalein were dependent linearly on their concentration with detection limit of 14.5 pM and 44.4 pM, respectively. Moreover, the proposed NIPA/AA-MWCNTs-GCE was also successfully applied for determination of luteolin and baicalein in peanut shell, Huang-qin and tomato samples.

The high pressure behavior of α-molybdenum boride (α-MoB2, P6/mmm) and β-molybdenum boride (β-MoB2, Rm) was studied up to a pressure of 32.1 GPa and 35.5 GPa, respectively. The bulk modulus values for α-MoB2 and β-MoB2 were 317 GPa and 299 GPa respectively, which fitted the Birch-Murnaghan equation of state. That the compressibility of MoB2 mainly depends on electron concentration but is less related to structure difference was reconfirmed in this study. An anomalous second-order transition was found in β-MoB2 at 26.6 GPa, which resulted in the structure softening and changing the anisotropy of β-MoB2. The anomalous transition found in β-MoB2 under high pressure may be attributable to the limitation of the B2–B2–B2 angle in puckered boron layers. These results will promote further understanding of the mechanical properties of transition metal borides (TMBs), and will be helpful in designing hard or superhard materials with TMBs.

We report joint theoretical and experimental research on the high-pressure structures of bismuth selenide (Bi2Se3) up to 50 GPa. Our first-principles structure prediction via calypso methodology meets our high-pressure X-ray diffraction experiments performed in diamond anvil cell. We established that the ambient-pressure rhombohedral phase transforms to a monoclinic C2/m structure at 9.8 GPa, and then to a monoclinic C2/c structure at 12.4 GPa. Above 22.1 GPa, we were able to identify that Bi2Se3 develops into a novel 9/10-fold structure, which was not taken by its other family members Bi2Te3 and Sb2Te3. The large differences in atomic core and electronegativity of Bi and Se are suggested to be the physical origin of the stabilization of this 9/10-fold structure. Our research work allows us to reveal a rich chemistry of Bi in the formation of 6, 7, 8, and 9/10-fold covalent bond with Se at elevated pressures.

Various LiFePO4 microstructures were synthesized via hydrothermal or solvothermal routes using different additives. In an aqueous solution, LiFePO4 spindles whose length was about 2 microm were obtained with the assistance of polyvinyl pyrrolidone (PVP). As PVP and P2O7(4-) added in water, ellipsoidal LiFePO4 particles which composed of nanoparticles around 100 nm in diameter were obtained. If the additive was cetyltrimethyl ammonium bromide (CTAB), sheet-like LiFePO4 crystals with the width of 100 nm were prepared. In the mixed solvents of water together with ethanol or acetylacetone, when adding CTAB or polyethylene glycol (20000), LiFePO4 plates or nanoparticles were obtained. The ellipsoidal LiFePO4 had the best electrochemical properties among all these products. It is found that the annealed samples were significantly better than the corresponding unannealed ones. Take the ellipsoidal LiFePO4 for example, the initial discharge capacity of annealed (161 mAh/g) was much higher than the unannealed ones (85 mAh/g) at 0.1 C and the former cell still could deliver a capacity of 143 mAh/g after 30 cycles.

Activation of C-C chemokine receptor type 7 (CCR7) has been demonstrated to mediate the occurrence and progression of non-small cell lung cancer (NSCLC). However, the potential therapeutic role of CCR7 inhibition in NSCLC is still obscure. Thus, the present study was conducted to investigate the molecular mechanism underlying the inhibition of CCR7 on cell apoptosis and epithelial-mesenchymal transition (EMT) in NSCLC A549 cells. Chemokine ligand 21 (CCL21) was used to activate CCR7 and the results revealed that CCR7 upregulation inhibited cell apoptosis and affected apoptosis‑related protein levels. However, CCR7-siRNA treatment markedly promoted apoptosis and suppressed inflammatory response and transforming growth factor β1 (TGF-β1)-induced EMT. In addition, CCR7‑siRNA inactivated the NF-κB signaling pathway and inhibition of NF-κB via its specific antagonist, pyrrolidine dithiocarbamate, indicated that NF-κB was involved in the CCR7-mediated apoptosis. In conclusion, upregulation of CCR7 promoted cell proliferation and inflammation in A549 cells. In conclusion, inhibition of CCR7 via siRNA treatment promoted cell apoptosis and suppressed the inflammatory response and TGF-β1‑induced EMT, which may be associated with NF-κB signaling.

We investigated the high pressure phases of CdF2 by a joint theoretical and experimental study. The structural and electronic properties of CdF2 were extensively explored to high pressure by ab initio calculations based on the density functional theory. A structural phase transition from the fluorite-type (Fm-3m, Z = 4 ) structure to the cotunnite-type (Pnma, Z = 4 ) structure was estimated below 8 GPa, and this phase transition was examined by the high pressure experiments up to 35 GPa at room temperature. Both high pressure angle dispersive X-ray diffraction and Raman spectroscopy experiments provided convincing evidence to verify the phase transition. Our work makes clear pressure-induced phase transitions and structural information of CdF2 under high pressure.

The in situ high-pressure behavior of the semiconductor antimony trioxide (Sb2O3) has been investigated by Raman spectroscopy techniques in a diamond anvil cell up to 20 GPa at room temperature. New peaks in the external lattice mode range emerged at a pressure above 8.6-15 GPa, suggesting that the structural phase transition occurred. The pressure dependence of Raman frequencies was obtained. The band at 139 cm-1 (assigned to group mode) has a pressure dependence of -0.475 cm-1/GPa and reveals significant softening at high pressure. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Graphitic carbon nitride (g-C3N4) has been synthesized via a two-step pyrolysis of melamine (C3H6N6) at 800°C for 2 h under vacuum conditions. X-ray diffraction (XRD) patterns strongly indicate that the synthesized sample is g-C3N4. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) morphologies indicate that the product is mainly composed of graphitic carbon nitride. The stoichiometric ratio of C:N is determined to be 0.72 by elemental analysis (EA). Chemical bonding of the sample has been investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). Electron energy loss spectroscopy (EELS) verifies the bonding state between carbon and nitrogen atoms. Optical properties of the g-C3N4 were investigated by PL (photoluminescence) measurements and UV–Vis (ultraviolet–visible) absorption spectra. We suppose its luminescent properties may have potential application as component of optical nanoscale devices. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were also performed.

The transition from sp2 to sp3 hybridization in boron nitride has been induced in plasma. Nano-crystals of cubic boron nitride (cBN) have been synthesized by direct current arc discharge method using hexagonal boron nitride (hBN) as the starting material. The characterization of the as-grown powders is carried out by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscopy. It has been shown that cBN and hBN grains with 20–60 nm in size co-exist in the powders. A reaction route of sublimation – re-hybridization – crystallization had been put forward to explain the mechanism of the hybridization transition and the growth of cBN by this method.

Zn1−XMnXS ( X = 0.85 % and 1.26%) nanoparticles have been synthesized using a specially designed equipment and we have studied the influence of doping Mn2+ on the surface energy of ZnS. The high pressure behaviors of ZnS nanocrystals with different dopant contents have been investigated using angle-dispersive synchrotron X-ray powder diffraction up to 45.1 GPa. Theoretical calculations show that doping with Mn2+ increases the surface energy of the nanocrystals. The theoretical result has been further corroborated by our experimental observation of an increase in the phase transition pressure of Mn2+ doped ZnS nanocrystals in diamond-anvil-cell studies.

Carbon filaments and nanometric carbon particles formed from methane on nano-sized Ni–Cu/Al2O3 catalyst at 720–830°C were investigated with a transmission electron microscope. Bamboo-shaped carbon filaments were found formed at moderate temperatures. Their morphology depends on the amount of copper doped into the catalyst, the composition of the feed gas and the reaction temperature. Under appropriate conditions, a morphologically pure bamboo-shaped carbon filament can be produced. It is likely that the formation of the quasi-liquid state of the metal nanoparticles during the growth of the carbon is critical for the formation of bamboo shape. The sensitivity of the carbon morphologies to the nano-carbon to the characteristics of catalyst and reaction conditions provides some room for the nanosize construction with carbon under moderate catalytic conditions.

The in situ high-pressure behavior of the semiconductor antimony trioxide (Sb2O3) is investigated by the Raman spectroscopy techniques and angle-dispersive synchrotron x-ray powder diffraction in a diamond anvil cell up to 31.5 and 30.7 GPa, respectively. New peaks observed in the external lattice mode range in the Raman spectra at 13.5 GPa suggest that the structural phase transition occurs. The group mode (140 cm−1) in Sb2O3 exhibits anomalous pressure dependence; that is, the frequency decreases gradually with the increasing pressure. High pressure synchrotron x-ray diffraction measurements at room temperature reveal that the transition from the orthorhombic structure to high-pressure new phase occurs at about 14.2 GPa, corresponding to the softening of the group optic mode (140 cm−1).

Being a best known thermoelectric material and a topological insulator at ambient condition, magic bismuth telluride (${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$) under pressure transforms into several superconducting phases, whose structures remain unsolved for decades. Here, we have solved the two long-puzzling low high-pressure phases as seven- and eightfold monoclinic structures, respectively, through particle-swarm optimization technique on crystal structure prediction. Above 14.4 GPa, we experimentally discovered that ${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$ unexpectedly develops into a Bi-Te substitutional alloy by adopting a body-centered cubic disordered structure stable at least up to 52.1 GPa. The continuously monoclinic distortion leads to the ultimate formation of the Bi-Te alloy, which is attributed to the $\mathrm{Bi}\ensuremath{\rightarrow}\mathrm{Te}$ charge transfer under pressure. Our research provides a route to find alloys made of nonmetallic elements for a variety of applications.

The high-pressure behaviors of SmFeO3 are investigated by angle-dispersive synchrotron X-ray powder diffraction under a pressure of up to 40.3 GPa at room temperature. The crystal structure of SmFeO3 remains stable at up to the highest pressure. The different pressure coefficients of the normalized axial compressibility are obtained to be βa = 0.60 × 10−3 GPa−1, βb = 0.79 × 10m3 GPa−1, βc = 1.28 × 10−3 GPa−1, and the bulk modulus (B0) is determined to be 293(3) GPa by fitting the pressure-volume data using the Birch—Murnaghan equation of state. Furthermore, the larger compressibility of the FeO6 octahedra suggests the evolution of the orthorhombic structure towards higher symmetry configuration at high pressures.

Using the angle-dispersive synchrotron x-ray powder diffraction technique in a diamond anvil cell, the high-pressure behaviors of antimony telluride (Sb2Te3) are explored up to 52.7 GPa at room temperature. Three high-pressure phases have been observed, at about 8.0 GPa, 13.2 GPa and above 21.6 GPa, respectively. Furthermore, the crystalline structures of these high-pressure phases are determined as monoclinic sevenfold C2/m phase, eightfold C2/c phase and disordered body-centered cubic structure (space group Im - 3m) respectively. The phase-transition sequences and pressures observed are well explained by first-principles calculations. The pressure dependence of the volume of all high-pressure phases is described by a third-order Birch-Murnaghan equation of state. All the high-pressure phases are metallic and the metallic character for beta-, gamma- and delta-Sb2Te3 increases in turn based on the results of the electronic density of states calculated for each high-pressure phase.

The high-pressure and high-temperature behaviors of anhydrite (CaSO4) are studied up to 53.5?GPa and 1800?K using double-sided laser heating Raman spectroscopy and x-ray diffraction in diamond anvil cells. The evidence of phase transition from an anhydrite structure to the monazite type was observed at about 2?GPa under cold compression. Another phase transition and a change in color of the sample from transparent to black have been also observed at a pressure of 33.2?GPa after laser heating. The new phase after laser heating persists to 53.5?GPa and 1800?K.