The effects of structure and morphology on lithium storage in single-wall carbon nanotube (SWNT) bundles were studied by electrochemistry and nuclear magnetic resonance techniques. SWNTs were chemically etched to variable lengths and were intercalated with Li. The reversible Li storage capacity increased from LiC(6) in close-end SWNTs to LiC(3) after etching, which is twice the value observed in intercalated graphite. All the nanotubes became metallic upon intercalation of Li, with the density of states at the Fermi level increasing with increasing Li concentration. The enhanced capacity is attributed to Li diffusion into the interior of the SWNTs through the opened ends and sidewall defects.

Single-walled carbon nanotubes were studied by (13)C nuclear magnetic resonance (NMR). Two types of (13)C nuclear spins were identified with different spin-lattice relaxation rates. The fast-relaxing component, assigned to metallic tubes, followed the relaxation behavior expected in metals, and the density-of-states at the Fermi level increased with decreasing tube diameter. The slow-relaxing component has a significantly lower density-of-states at the Fermi level. Exposure to oxygen has a substantial effect on relaxation rates of both components.

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Epidermal growth factor (EGF) is a 53-amino acid peptide that plays an important role in regulating cell growth, survival, migration, apoptosis, proliferation, and differentiation. In addition, EGF has been established to be an effective intestinal regulator helping to protect intestinal barrier integrity, which was essential for the absorption of nutrients and health in humans and animals. Several researches have demonstrated that EGF via binding to the EGF receptor and subsequent activation of Ras/MAPK, PI3K/AKT, PLC-γ/PKC, and STATS signal pathways regulates intestinal barrier function. In this review, the relationship between epidermal growth factor and intestinal development and intestinal barrier is described, to provide a better understanding of the effects of EGF on intestine development and health.

Adsorption isotherms of methane and ethane in single-walled carbon nanotubes ͑SWNTs͒ were measured by 1 H nuclear magnetic resonance ͑NMR͒ at room temperature. It is shown that the interior of SWNTs becomes available for methane and ethane adsorption after cutting of SWNTs. Such endohedral adsorption dominates methane and ethane adsorption in SWNTs, at least below 1 MPa. The average exchange time between molecules adsorbed inside SWNTs and free gas molecules outside was estimated to be on the order of 80 ms. It is shown that exposure to oxygen has no effect on methane and ethane endohedral adsorption in SWNTs, suggesting that the adsorption energy of oxygen molecules inside SWNTs is small compared to that of methane. 13 C NMR indicates that under atmospheric pressure and room temperature helium atoms could access the interstitial sites of SWNT bundles whereas H 2 , CO 2 , and N 2 molecules could not.

The epidermal growth factor (EGF) has been widely used for protection of stress-induced intestinal mucosa dysfunction. However, whether EGF would alleviate oxidative injury and reduce apoptosis in porcine intestine is not yet known. Therefore, the aim of this study was to investigate the effect of EGF on lipopolysaccharides (LPS)-induced induction of oxidative stress and ensuing apoptosis in the porcine intestinal epithelial cell line, IPEC-J2. The present study showed that EGF significantly increased cell viability and decreased the LPS-induced induction of apoptosis, dehydrogenase (LDH) release and malonaldehyde (MDA) production. EGF also (i) decreased expression of the pro-apoptotic genes Fas, Bax, Cascase-3, Cascase-8, Cascase-9, and proteins such as P53, Fas, Bax, Caspase3; (ii) increased antiapoptotic protein B-cell lymphoma 2 (Bcl2) expression; (iii) increased mRNA levels of the nuclear factor erythroid 2-related factor 2 (Nrf2) related genes Nrf2, manganese superoxide dismutase (SOD2), catalase (CAT), glutathione peroxidase (GSH-Px), heme oxygenase (HO-1) and quinone oxidoreductase (NQO1); (iv) protein level of Nrf2-realeted proteins Nrf2, HO-1, NQO1; and (v) total antioxidant capacity (T-AOC), CAT, SOD, GSH-Px concentrations. Collectively, our results indicated that EGF enhanced Nrf2 protein expression, and upregulated the expression of phase II metabolizing enzymes (such as HO-1 and NQO1) and antioxidative enzymes (SOD, CAT and GSH-Px) to alleviate oxidative injury, and then protect IPEC-J2 cells from apoptosis induced by LPS.

An individual single-walled carbon nanotube (SWNT) has been shown [1-4] to exhibit remarkable electronic properties which depend on its diameter and chirality. In this work, the 13C nuclear magnetic resonance technique is used to measure quantitatively the electronic density-of-state (DOS) at the Fermi level in a bulk SWNT sample. Two types of 13C nuclear spins are observed with drastically different nuclear spin-lattice relaxation time (Tl). About onethird of the 13C nuclear spins with shorter Tl, are identified to reside at the metallic SWNTs and two-thirds can be associated with the semiconducting SWNTs. For the metallic SWNTs, the DOS at the Feimi level is measured quantitatively, which is about 0.022 states/(eV·atom·spin). The measured electronic DOS at the Fermi level agrees with the theoretical prediction for metallic tubes. This study also found that the semiconducting SWNTs in bundles, in fact, possess weak metallic characters. This indicates that tube-tube interactions within SWNT bundles could change the electronic properties.