Interaction of Cobalt Nanoparticles with Oxygen- and Nitrogen-Functionalized Carbon Nanotubes and Impact on Nitrobenzene Hydrogenation Catalysis

The type and the amount of functional groups on the surface of carbon nanotubes (CNTs) were tuned to improve the activity of supported Co nanoparticles in hydrogenation catalysis. Surface nitrogen species on CNTs significantly promoted the decomposition of the cobalt precursor and the reduction of cobalt oxide, and improved the resistance of metallic Co against oxidation in ambient atmosphere. In the selective hydrogenation of nitrobenzene in the gas phase, Co supported on CNTs with the highest surface nitrogen content showed the highest activity, which is ascribed to the higher reducibility and the lower oxidation state of the Co nanoparticles under reaction conditions. For Co nanoparticles supported on CNTs with a smaller amount of surface nitrogen groups, a repeated reduction at 350 °C was essential to achieve a comparable high catalytic activity reaching 90% conversion at 250 °C, pointing to the importance of nitrogen species for the supported Co nanoparticles in nitrobenzene hydrogenation

Control of Phase Coexistence in Calcium Tantalate Composite Photocatalysts for Highly Efficient Hydrogen Production

Design and fabrication of semiconductor based composite photocatalysts with matching band structure is an important strategy to improve charge separation of photogenerated electron–hole pairs for photocatalytic hydrogen production. In our study, by aid of the simple and cost-effective molten salts method, a series of phase-controlled and composition-tuned calcium tantalate composite photocatalysts has been prepared by adjusting the initial atomic ratio of Ta/Ca precursors. We demonstrate the strong correlation between the photocatalytic activities of calcium tantalate composite photocatalysts for hydrogen evolution and respective phase compositions. Without any cocatalysts, these composites with the optimized phase composition of cubic α-CaTa₂O₆/hexagonal Ca₂Ta₂O₇, cubic CaTa₂O₆/hexagonal Ca₂Ta₂O₇/orthorhombic β-CaTa₂O₆, or cubic α-CaTa₂O₆/orthorhombic β-CaTa₂O₆ showed very high photocatalytic H₂ production activities in the presence of methanol. It is attributed mainly to a significantly improved photoexcited charge carrier separation via the junctions and interfaces in the composites. Further by in situ photodeposition of noble metal nanoparticles (Pt or Rh) as cocatalysts the photocatalytic activity of these composites was greatly promoted for H₂ production. The study on convenient fabrication of phase-coexisting composite photocatalysts with matching band structure for improving the photocatalytic hydrogen production sheds light on developing efficient composite photocatalyst as a means for conversion of solar energy to chemical energy

Anti-CD70-IFN-γ immunocytokines display species-specific antiviral activity.

<p>Murine (RenCa) or human (Caki-1) RCC cells were pre-treated for 16 h with anti-CD70 immunocytokines bearing either murine (m) or human (h) IFN-γ (‘Anti-CD70 fusion’, 50 ng/ml). As controls, parallel populations of these cells were pre-treated for 16 h with recombinant murine or human IFN-γ (‘Native’, 10 ng/ml), or with unfused anti-CD70 antibody (50 ng/ml). Following pre-treatment, cells were infected with VSV-GFP (MOI = 5 for RenCa, 0.05 for Caki-1). (A) Infected cells were photographed by brightfield (for demonstration of cytopathic effect) or by fluorescence (to show viral replication) microscopy 20 h post-infection. (B) Viability of cells treated as above was determined 20 h post-infection. (C) VSV progeny yield from supernatants of infected cells was determined by standard plaque assay 20 h post-infection. Error bars represent mean +/− S.D, n = 3.</p

Anti-CD70-IFN-γ immunocytokines are cytotoxic to RCC cell lines in the presence of bortezomib.

<p>RCC cell lines RenCa (A) or Caki-1 (B) were treated either with unfused anti-CD70 antibody (‘Anti-CD70’), with recombinant, native human or murine IFN-γ (‘Native’), or with human or murine IFN-γ immunocytokines (‘Anti-CD70 fusion’) for 72 h in the presence of their MTD of bortezomib (black bars). As controls, these cells were also treated with each agent singly (grey bars). In conditions requiring bortezomib co-treatment, bortezomib was added to cells 1 h before IFN-γ.</p

Anti-CD70-IFN-γ immunocytokines bind human CD70.

<p>(A) 293T cells were transfected with an expression vector encoding Myc-tagged human CD70 (‘CD70’), or with an empty vector (‘Vec’). 24 h post-transfection, cells were examined for CD70 expression in lysates by anti-Myc immunoblotting (inset, top panel; β-actin loading control, bottom panel), or on the cell surface by FACS staining with a FITC-conjugated anti-CD70 monoclonal antibody. (B) 293T cells were transfected as in A with either an empty vector (‘Vec’) or an expression vector encoding Myc-tagged CD70 (‘CD70’). 24 h post-transfection, cells were incubated with either Rituximab as an isotype control human IgG1 antibody (‘Isotype Control’, left panel), or with immunocytokines bearing either murine (m) or human (h) IFN-γ (‘Anti-CD70 fusion’), and, following labeling with FITC-conjugated anti-human IgG secondary antibodies, analyzed by FACS for CD70 expression. (C) The ATCC-derived RCC cell lines 786-O, 769-P, Caki-1, and ACHN were incubated with either an isotype control human IgG1 antibody (Rituximab, dashed line), anti-CD70-mIFN-γ immunocytokine (thin solid line), or anti-CD70-hIFN-γ immunocytokine (thick solid line), followed by labeling with FITC-conjugated anti-human IgG secondary antibodies and detection of fluorescence by FACS. All four ATCC cell lines are robustly and specifically stained by both anti-CD70 IFN-γ immunocytokines.</p

Generation and purification of mIFN-γ and hIFN-γ immunocytokines targeting CD70.

<p>(A) Two plasmids – pMAZ-IgH and pMAZ-IgL – were used as backbones to construct and express anti-CD70 immunocytokines bearing either murine (m) or human (h) IFN-γ. pMAZ-IgH expresses the anti-CD70 heavy chain separated from murine or human IFN-γ by a flexible (Gly)₄-Ser linker. pMAZ-IgL encodes the anti-CD70 light chain. For details of construction, expression and purification, please see the Materials and Methods section. (B) Coomassie Blue-stained SDS-PAGE gel of mIFN-γ-anti-CD70 immunocytokine (lane 1), and hIFN-γ-anti-CD70 immunocytokine (lane 2) purified from supernatants of 293T cells after transfection with the plasmids described in A.</p

Anti-CD70-IFN-γ immunocytokines exert RIP1-dependent necrotic activity on RCC cell lines.

<p>(A) RenCa, Caki-1, 786-O, or HRC63 cells were co-treated with bortezomib (MTD) and, respectively, murine (RenCa) or human (Caki-1, 786-O, and HRC63) IFN-γ immunocytokines (‘Anti-CD70 fusion’, 50 ng/ml) in the presence or absence of 50 μM RIP1 kinase inhibitor Nec-1 for 72–84 h. The MTD of bortezomib for 786-0 and HRC63 cells was 4 ng/ml and 2 ng/ml, respectively. Cell viability was determined by Trypan Blue exclusion analysis. Error bars represent mean +/− S.D; n = 3. (B) RenCa, Caki-1, 786-O, or HRC63 cells pre-treated without (-Nec-1) or with (+Nec-1) for 1h, before co-treatment with IFN-γ immunocytokines and bortezomib as in (A), were photographed 72 h post-treatment.</p

Spatial Distribution of Brønsted Acid Sites Determines the Mobility of Reactive Cu Ions in the Cu-SSZ-13 Catalyst during the Selective Catalytic Reduction of NO_<i>x</i> with NH₃

The formation of dimer-Cu species, which serve as the active sites of the low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR), relies on the mobility of CuI species in the channels of the Cu-SSZ-13 catalysts. Herein, the key role of framework Brønsted acid sites in the mobility of reactive Cu ions was elucidated via a combination of density functional theory calculations, in situ impedance spectroscopy, and in situ diffuse reflectance ultraviolet–visible spectroscopy. When the number of framework Al sites decreases, the Brønsted acid sites decrease, leading to a systematic increase in the diffusion barrier for [Cu­(NH3)2]+ and less formation of highly reactive dimer-Cu species, which inhibits the low-temperature NH3-SCR reactivity and vice versa. When the spatial distribution of Al sites is uneven, the [Cu­(NH3)2]+ complexes tend to migrate from an Al-poor cage to an Al-rich cage (e.g., cage with paired Al sites), which effectively accelerates the formation of dimer-Cu species and hence promotes the SCR reaction. These findings unveil the mechanism by which framework Brønsted acid sites influence the intercage diffusion and reactivity of [Cu­(NH3)2]+ complexes in Cu-SSZ-13 catalysts and provide new insights for the development of zeolite-based catalysts with excellent SCR activity by regulating the microscopic spatial distribution of framework Brønsted acid sites

Spatial Distribution of Brønsted Acid Sites Determines the Mobility of Reactive Cu Ions in the Cu-SSZ-13 Catalyst during the Selective Catalytic Reduction of NO_<i>x</i> with NH₃

The formation of dimer-Cu species, which serve as the active sites of the low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR), relies on the mobility of CuI species in the channels of the Cu-SSZ-13 catalysts. Herein, the key role of framework Brønsted acid sites in the mobility of reactive Cu ions was elucidated via a combination of density functional theory calculations, in situ impedance spectroscopy, and in situ diffuse reflectance ultraviolet–visible spectroscopy. When the number of framework Al sites decreases, the Brønsted acid sites decrease, leading to a systematic increase in the diffusion barrier for [Cu­(NH3)2]+ and less formation of highly reactive dimer-Cu species, which inhibits the low-temperature NH3-SCR reactivity and vice versa. When the spatial distribution of Al sites is uneven, the [Cu­(NH3)2]+ complexes tend to migrate from an Al-poor cage to an Al-rich cage (e.g., cage with paired Al sites), which effectively accelerates the formation of dimer-Cu species and hence promotes the SCR reaction. These findings unveil the mechanism by which framework Brønsted acid sites influence the intercage diffusion and reactivity of [Cu­(NH3)2]+ complexes in Cu-SSZ-13 catalysts and provide new insights for the development of zeolite-based catalysts with excellent SCR activity by regulating the microscopic spatial distribution of framework Brønsted acid sites

Spatial Distribution of Brønsted Acid Sites Determines the Mobility of Reactive Cu Ions in the Cu-SSZ-13 Catalyst during the Selective Catalytic Reduction of NO_<i>x</i> with NH₃

The formation of dimer-Cu species, which serve as the active sites of the low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR), relies on the mobility of CuI species in the channels of the Cu-SSZ-13 catalysts. Herein, the key role of framework Brønsted acid sites in the mobility of reactive Cu ions was elucidated via a combination of density functional theory calculations, in situ impedance spectroscopy, and in situ diffuse reflectance ultraviolet–visible spectroscopy. When the number of framework Al sites decreases, the Brønsted acid sites decrease, leading to a systematic increase in the diffusion barrier for [Cu­(NH3)2]+ and less formation of highly reactive dimer-Cu species, which inhibits the low-temperature NH3-SCR reactivity and vice versa. When the spatial distribution of Al sites is uneven, the [Cu­(NH3)2]+ complexes tend to migrate from an Al-poor cage to an Al-rich cage (e.g., cage with paired Al sites), which effectively accelerates the formation of dimer-Cu species and hence promotes the SCR reaction. These findings unveil the mechanism by which framework Brønsted acid sites influence the intercage diffusion and reactivity of [Cu­(NH3)2]+ complexes in Cu-SSZ-13 catalysts and provide new insights for the development of zeolite-based catalysts with excellent SCR activity by regulating the microscopic spatial distribution of framework Brønsted acid sites