Correction: Synthesis of vertically aligned carbon nanotube arrays on polyhedral Fe/Al2O3 catalysts.

Correction for 'Synthesis of vertically aligned carbon nanotube arrays on polyhedral Fe/Al2O3 catalysts' by Jun Liu et al., Chem. Commun., 2011, 47, 6434-6436, https://doi.org/10.1039/C1CC10878F.

HTLV-1 Tax upregulates early growth response protein 1 through nuclear factor-κB signaling.

Human T cell leukemia virus type 1 (HTLV-1) is a complex retrovirus that causes adult T cell leukemia (ATL) in susceptible individuals. The HTLV-1-encoded oncoprotein Tax induces persistent activation of the nuclear factor-κB (NF-κB) pathway. Early growth response protein 1 (EGR1) is overexpressed in HTLV-1-infected T cell lines and ATL cells. Here, we showed that both Tax expression and HTLV-1 infection promoted EGR1 overexpression. Loss of the NF-κB binding site in the EGR1 promotor or inhibition of NF-κB activation reduced Tax-induced EGR1 upregulation. Tax mutants unable to activate NF-κB induced only slight EGR1 upregulation as compared with wild-type Tax, confirming NF-κB pathway involvement in EGR1 regulation. Tax also directly interacted with the EGR1 protein and increased endogenous EGR1 stability. Elevated EGR1 in turn promoted p65 nuclear translocation and increased NF-κB activation. These results demonstrate a positive feedback loop between EGR1 expression and NF-κB activation in HTLV-1-infected and Tax-expressing cells. Both NF-κB activation and Tax-induced EGR1 stability upregulated EGR1, which in turn enhanced constitutive NF-κB activation and facilitated ATL progression in HTLV-1-infected cells. These findings suggest EGR1 may be an effective anti-ATL therapeutic target.

Non-Gaussian diffusion alterations on diffusion kurtosis imaging in patients with early Alzheimer's disease.

OBJECTIVE: To evaluate non-Gaussian diffusion changes of the whole-brain and its correlation with cognitive performance in patients with early Alzheimer's disease (AD), using diffusion kurtosis imaging (DKI). METHODS: Twenty-six patients with early AD and twenty-six normal controls underwent diffusion imaging. Seven parametric maps were calculated from multiple b-value diffusion data, including mean kurtosis (MK), axial kurtosis (AK), radial kurtosis (RK), fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AxD) and radial diffusivity (RD). Voxel-based analyses were performed to evaluate the group difference between the AD patients and normal controls. Then correlation between the diffusion parameters (MK, FA and MD) and cognitive performance were analyzed in AD patients. RESULTS: For AD patients, increased MD, AxD and RD were found in white matter (WM), including the genu of corpus callosum, bilateral cingulate bundle, bilateral temporal and frontal WM, and were also found in gray matter (GM), including the bilateral temporal GM, parahippocampal gyrus, hippocampus, cingulate gyrus, thalamus, and amygdala. These regions were partially overlapped with those showing decreased FA, MK, AK and RK. However, only kurtosis indices could detect the significant differences in the lentiform nucleus between AD patients and health control. DKI indices in AD patients significantly correlated with the clinical scores in genu of CC, cingulate bundle, temporal and frontal lobe, while the voxel number showing significant correlation with MK was more than that with FA and MD. CONCLUSIONS: Early AD patients already have microstructural changes in both WM and GM. DKI can provide supplementary information in reflecting these changes and may be sensitive in diagnosing early AD.

Pretreatment control of carbon nanotube array growth for gas separation: alignment and growth studied using microscopy and small-angle X-ray scattering.

Aligned multiwalled carbon nanotube (CNT) arrays were prepared using chemical vapor deposition of C2H4 on Fe catalyst at 750 °C. CNT array height and alignment depends strongly on the duration of H2 pretreatment, with optimal height and alignment achieved using 10-15 min pretreatment. Small-angle X-ray scattering (SAXS) was used to quantify the alignment, distribution, and size of the CNTs in arrays produced from varying pretreatment times and the results correlated with microscopy measurements. SAXS analysis revealed that the higher section of the CNT arrays exhibited better alignment than the lower section. Combining these insights with transmission electron microscopy measurements of the CNT defects within each array enable a mechanism for the CNT growth to be proposed, where the loss of alignment arises from deformation of the CNTs during their growth. Gas permeation test across densified CNT arrays indicated that the alignment of the CNT array plays an important role in the gas transport, and that the gas diffusion across the well-aligned CNT arrays was enhanced by a factor of ~45, which is much more than that across the poorly aligned CNT arrays, with an enhancement factor of ~8.

Facile preparation of free-standing carbon nanotube arrays produced using two-step floating-ferrocene chemical vapor deposition.

A two-step floating-ferrocene chemical vapor deposition method has been devised for the preparation of single-layered aligned carbon nanotube (CNT) arrays. In the first step, uniform Fe catalysts are in situ produced and coated on a Si substrate from ferrocene; single-layered CNT arrays are prepared on these catalysts from ethylene in the second step. The effect of ferrocene loading on the distribution of Fe catalysts, as well as the morphology, diameter, and height of the CNT arrays, was investigated. A novel vacuum extraction process was employed to release the as-prepared CNT array from the Si wafer after water etching at 750 °C. The structural integrity of the free-standing arrays was preserved after the detachment process. The interface between the substrate and the as-grown CNT array was examined. The Fe catalyst distribution on the Si substrate remained homogeneous when the CNT array was removed, and the tops and bottoms of the arrays had different structures, suggesting that the arrays were formed predominantly by a base-growth mode. These free-standing arrays could potentially be applied in membrane or electronic applications.

Synthesis of vertically aligned carbon nanotube arrays on polyhedral Fe/Al2O3 catalysts.

Polyhedral Fe/Al(2)O(3) catalysts prepared by an impregnation method were used for the synthesis of vertically aligned carbon nanotube (CNT) arrays from the pyrolysis of ethylene at 800 °C.

Permeation hysteresis in PdCu membranes.

H 2 permeation hysteresis has been observed during cycling of a 3 mum thick supported PdCu membrane with approximately 50 atom % Pd through the fcc/bcc (face-centered cubic/body-centered cubic) miscibility gap between 723 and 873 K. Structural investigations after annealing of membrane fragments under H 2 at 823 K reveal retardation of the fcc(H) --> bcc(H) transition, which is attributed to the occurrence of metastable hydrogenated fcc PdCu(H) phases. The H(2) flux at 0.1 MPa H(2) pressure difference in the well-annealed bcc single phase regime below 723 K can be described by J(H2) = (1.3 +/- 0.2) mol.m (-2).s (-1) exp[(-11.1 +/- 0.6) kJ.mol (-1)/( RT)] and that in the fcc single phase regime above 873 K by J(H2) = (7 +/- 2) mol.m (-2).s (-1) exp[(-30.3 +/- 2.5) kJ.mol (-1)/( RT)].

Segregation and H2 transport rate control in body-centered cubic PdCu membranes.

The H2 permeation of a supported 2 microm thick Pd48Cu52 membrane was investigated between 373 and 909 K at DeltaP=0.1 MPa. The initial H2 flux was 0.3 mol.m(-2).s(-1) at 723 K with an ideal H2/N2 selectivity better than 5000. The membrane underwent a bcc-fcc (body-centered cubic to face-centered cubic) phase transition between 723 and 873 K resulting in compositional segregation. After reannealing at 723 K the alloy layer reverted to a bcc structure although a small fcc fraction remained behind. The mixed-phase morphology was analyzed combining X-ray diffraction with scanning electron microscopy-energy-dispersive spectroscopic analysis (SEM-EDS) measurements, which revealed micrometer-scale Cu-enriched bcc and Cu-depleted fcc domains. The H2 flux JH2 of the fcc Pd48Cu52 single phase layer prevailing above 873 K could be described by an Arrhenius law with JH2=(7.6+/-4.9) mol.m(-2).s(-1) exp[(-32.9+/-4.5) kJ.mol(-1)/(RT)]. The characterization of the H2 flux in the mixed-phase region required two Arrhenius laws, i.e., JH2=(1.35+/-0.14) mol.m(-2).s(-1) exp[(-10.3+/-0.5) kJ.mol(-1)/(RT)] between 523 and ca. 700 K and JH2=(56.1+/-9.3) mol.m(-2).s(-1) exp[(-25.3+/-0.6) kJ.mol(-1)/(RT)] below 454 K. The H2 flux exhibited a square root pressure dependence above 523 K, but the pressure exponent gradually increased to 0.77 upon cooling to 373 K. The activation energy and pressure dependence in the intermediate temperature range are consistent with a diffusion-limited H2 transport, while the changes of these characteristics at lower temperatures indicate a desorption-limited H2 flux. The prevalence of desorption as the permeation rate-limiting step below 454 K is attributed to the pairing of an extraordinarily high hydrogen diffusivity with a marginal hydrogen solubility in bcc PdCu alloys. These result in an acceleration of the bulk diffusion rate and a deceleration of the desorption rate, respectively, allowing the bulk diffusion rate to surpass the desorption rate up to relatively high temperatures.