Very High-Quality Single-Walled Carbon Nanotubes Grown Using a Structured and Tunable Porous Fe/MgO Catalyst

Fe/MgO nanoparticle catalysts were prepared and used to grow single-walled carbon nanotubes (SWCNTs) from the decomposition of methane. The porous structure of the catalyst can be tailored by an ethanol−thermal treatment and calcination. Catalysts with sufficiently large pores (50 nm to 5 μm) can produce very high-quality SWCNTs that had an intensity ratio of D band to G band in their Raman spectra of less than 0.02−0.03. These SWCNTs had fewer defects than any other SWNT products from the chemical vapor deposition process previously reported

CO₂-Assisted SWNT Growth on Porous Catalysts

The effect of CO2 on the synthesis of single-walled carbon nanotubes (SWNTs) by methane decomposition on a Fe/Mo/MgO porous catalyst was investigated. Characterizations of the change in methane conversion with time, XRD and SSA of the catalyst, Raman spectroscopy, TGA, and the specific surface area (SSA) of SWNTs showed that CO2 inhibited the formation of amorphous carbon around the catalyst and also interacted with the MgO support of the catalyst, which decreased its particle size and increased the SSA of the catalyst. The result was an increase in the yield, purity, and SSA of SWNTs. These results indicated that the limited and small space in the pores of the porous catalyst made it difficult to increase the SWNTs in high yield. The addition of CO2, by destroying the structure of the catalyst and decreasing the catalyst size, provides a new route to increase the yield, purity, and SSA of SWNTs

Animal observation groups.

<p>Animal observation groups.</p

Phospholipid–Graphene Nanoassembly as a Fluorescence Biosensor for Sensitive Detection of Phospholipase D Activity

A novel phospholipid–graphene nanoassembly is developed based on self-assembly of phospholipids on nonoxidative graphene surfaces. The nanoassembly can be prepared easily through noncovalent hydrophobic interactions between the lipid tails and the graphene without destroying the electronic conjugation within the graphene sheet. This imparts the nanoassembly with desired electrical and optical properties with nonoxidative graphene. The phospholipid coating offers excellent biocompatibility, facile solubilization, and controlled surface modification for graphene, making the nanoassembly a useful platform for biofunctionalization of graphene. The nanoassembly is revealed to comprise a bilayer of phospholipids with a reduced graphene oxide sheet hosting in the hydrophobic interior, thus affording a unique planar mimic of the cellular membrane. By using a fluorescein-labeled phospholipid in this nanoassembly, a fluorescence biosensor is developed for activity assay of phospholipase D. The developed biosensor is demonstrated to have high sensitivity, wide dynamic range, and very low detection limit of 0.010 U/L. Moreover, because of its single-step homogeneous assay format it displays excellent robustness, improved assay simplicity and throughput, as well as intrinsic ability to real-time monitor the reaction kinetics

Improvement of Fe/MgO Catalysts by Calcination for the Growth of Single- and Double-Walled Carbon Nanotubes

Calcination at 900−1000 °C for 8−12 h of an Fe/MgO catalyst prepared by impregnation was found to result in a uniform MgFe2O4/MgO solid solution that showed a successful settling of well-dispersed iron species into the MgO lattice. During methane reduction, many iron-containing particles with a diameter of about 4 nm were formed on the catalyst surface to provide numerous active sites for the growth of single- and double-walled carbon nanotubes. There was a significant improvement of the Fe/MgO catalyst that resulted in a high yield of impurity-free nanotubes. Using C2H4 cracking at 600 °C and transmission electron microscope observations, the Fe species distribution in the catalysts and microscope images of nanotube growth were described in detail. H2 reduction of the calcined Fe/MgO catalyst was found to cause the formation of iron layers on the catalyst surface, which resulted in the growth of only carbon layers. The results are useful for understanding changes in the metal species distribution in the catalysts and the nanotube growth mechanism, and they provide a simple method to improve Fe/MgO catalysts

Tissue self-repair after trauma indicated by immunohistochemical staining and semi-quantitative analysis of PCNA, Col I and OCN.

<p>(A, C, E) Immunohistochemical assays of the expression of PCNA (A), Col I (C) and OCN (E). (B, D, F) Bar graphs represent their expression density in unit area of bone marrow or unit area of bone trabeculae. (A) OBs; (C) a. OBs, b. osteocytes, c. trabeculae, d. VECs, e. OCs. The expression of PCNA decreased after trauma, and began to be detected in OBs 2 weeks after trauma and was maintained during the following time. Col I increased in the bone marrow for less than 1 week after trauma, and was significantly accumulated in the trabeculae by the end of the study. Both OBs and OCs also expressed increased levels of Col I following trauma. A significant decrease in OCN was detected 3 days after trauma, but it increased significantly 2 weeks later. High levels of OCN were consistently associated with peri-VECs and the fibrous medulla. N: normal group; 3 d, 1 w, 2 w, 3 w: 3 days, 1 week, 1 weeks, 3 weeks post-trauma, respectively. Quantification was based on at least 10 fields per section. *<i>P</i><0.05 vs. normal group.</p

Growing 20 cm Long DWNTs/TWNTs at a Rapid Growth Rate of 80−90 μm/s

Growing 20 cm Long DWNTs/TWNTs at a Rapid Growth Rate of 80−90 μm/

Histopathological images of the traumatic ONFH rabbit model, and immunohistochemical staining and semi-quantitative analysis of vWF and CD105.

<p>(A) Representative images of a section of femoral head including cartilage stained with H&E. Scale bar = 200 µm. In the injured femoral head, the number of empty lacunae increased and hematopoietic tissue diminished significantly, but cartilage did not exhibit any obvious pathological changes. Immature fibrotic tissue and appositional bone formation were observed under the cartilage from 3 days after trauma, followed by an increase in the number of OBs 2 weeks later. a. empty lacuna; b. immature fibrotic tissue; c. appositional bone formation; d. OBs. (B) Bar graphs represent the ratio of bone marrow cells to the area of bone marrow (a), the ratio of empty lacunae to the area of trabeculae (b), thinning trabeculae (c) and grey scale (d), respectively. (C) Immunohistochemical assays of vWF expression. Scale bar = 50 µm. (D) Blood vessels were counted according to positive staining of vWF in combination with appropriate vessel structure. Following trauma, the structure of the blood vessels became increasingly compromised and the number of blood vessels decreased. Arrows = microvessels or arteries. (E) Immunohistochemical assays of vWF expression. Scale bar = 20 µm. (F) Bar graphs represent the expression density of CD105 as unit area of bone marrow or unit area of bone trabeculae. The expression of CD105 until 3 weeks after trauma suggested the presence of revascularization in the injured femoral head. N: normal group; 3 d, 1 w, 2 w, 3 w: 3 days, 1 week, 2 weeks, 3 weeks post-trauma, respectively. Quantification was based on at least 10 fields per section. *<i>P</i><0.05 vs. normal group.</p

Identification of MSC pluripotent potential.

<p>Undifferentiated MSCs (a–e), osteoblasts (f–j), chondroblasts (k–o), and adipocytes (p–t) were left unstained (a, f, k, & p), or stained with Alizarin Red at day 21 (b, g, l, & q), NBT-BCIP at day 14 (c, h, m, & r), Alcian blue at day 27 (d, i, n, & s), or Oil Red O at day 27 (e, j, o, & t). Scale bar = 50 µm.</p

Immunohistochemical detection and semi-quantitative analysis of HGF expression (A), phosphorylation of ERK1/2 (p-ERK1/2) (B) and Akt (p-Akt) (C).

<p>There was a little increase in HGF after trauma. After the transplantation of MSCs, the HGF level increased significantly at as early as 2 days, which was concomitant with increased p-ERK1/2. The HGF level decreased gradually for 2 weeks after transplantation, followed by a significant increase in Akt activation. The effects were most marked in the animals treated with HGF-transgenic MSCs. ^*<i>P</i><0.05, compared with the normal group. ^#<i>P</i><0.05, compared with the non-infected MSC-treated group. Scale bar = 50 µm.</p