Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 25
Filter
Add more filters










Publication year range
1.
Mater Horiz ; 10(10): 4463-4469, 2023 Oct 02.
Article in English | MEDLINE | ID: mdl-37526614

ABSTRACT

Developing advanced porous materials with industrial potential to separate multicomponent gas mixtures that are structurally similar is a crucial but challenging task. Here, we report the efficient one-step separation of ethylene (C2H4) from acetylene (C2H2) and carbon dioxide (CO2) using an ultramicroporous metal-organic framework UTSA-16. The synergistic effect of the polarized carboxyl groups and coordinated water molecules in its pore channel enables the material to have high uptakes for C2H2 and CO2 due to electrostatic potential matching, as well as excellent separation selectivity against C2H4. Breakthrough experiments suggest that UTSA-16 can efficiently separate 99.9% pure C2H4 from ternary mixtures with a high productivity of 403 L kg-1. Moreover, the preparation cost of UTSA-16 is significantly lower than other related adsorbents by 40-2000 times, indicating its unique potential for industrial applications.

2.
J Colloid Interface Sci ; 646: 361-369, 2023 Sep 15.
Article in English | MEDLINE | ID: mdl-37201464

ABSTRACT

Developing efficient and robust non-precious-metal-based hydrogen evolution reaction (HER) catalysts is highly desirable but remains quite challenging for alkaline freshwater/seawater electrolysis. In the present study, we report a theory-guided design and synthesis of a nickel foam (NF) supported N-doped carbon-coated (NC) nickel (Ni)/chromium nitride (CrN) nanosheets (NC@CrN/Ni) as a highly active and durable electrocatalyst. Our theoretical calculation firstly reveals that CrN/Ni heterostructure can greatly promote the H2O dissociation via hydrogen-bond induced effect, and the N site can be optimized by hetero coupling to achieve a facile hydrogen associative desorption, thereby significantly boosting alkaline HER. Guided by theoretical calculation, we prepared the nickel-based metal-organic framework as a precursor, and introduced the Cr by the subsequent hydrothermal treatment, finally obtained the target catalyst by ammonia pyrolysis. Such a simple process ensures the exposure of abundant accessible active sites. Consequently, the as-prepared NC@CrN/Ni catalyst exhibits outstanding performance in both alkaline freshwater and seawater, with the respective overpotential of only 24 and 28 mV at a current density of 10 mA cm-2, respectively. More impressively, the catalyst also possesses superior durability in the constant-current test of 50 h at the different current densities of 10, 100, and 1000 mA cm-2.

3.
Chemistry ; 28(66): e202202105, 2022 Nov 25.
Article in English | MEDLINE | ID: mdl-35998025

ABSTRACT

Herein, the synthesis of a new type of catalyst, SBA-M (Schiff complex of different metal types grafted on SBA-15) based on a quaternization reaction, is described. Various amounts of ionic liquid were grafted into the pore channels of SBA-15 using the post-grafting method, which allowed the ionic liquid to be grafted into the pore channels restrictively. Notably, over six cycles, SBA-Mn (0.2) has been shown to maintain its catalytic activity and stability. In addition, a reaction mechanism for the cycloaddition of CO2 with epoxides based on density-functional theory is proposed. The cycloaddition reaction of CO2 and epoxides is an efficient way of carbon fixation. It is demonstrated that the metal coordinated with the oxygen atom of the epoxides and that a halogen attacked the carbon of epoxides. Moreover, theoretical calculations and synthesis strategy provide a new approach for CO2 conversion.

4.
ACS Appl Mater Interfaces ; 14(16): 18816-18824, 2022 Apr 27.
Article in English | MEDLINE | ID: mdl-35417130

ABSTRACT

Developing a high-performance electrocatalyst for hydrogen evolution reaction (HER) requires a comprehensive consideration of the three key factors, that is, intrinsic activity, electric conductivity, and active site number. Herein, we report the facile synthesis of a self-supported Ni2P/WO2.83 heterointerface microsphere as a highly active and low-cost catalyst for alkaline HER, which has simultaneously addressed these key issues by a joint application of heterointerface construction and defect and architecture engineering strategies. Our density functional theory calculations revealed Ni2P and WO2.83 optimized by the interface coupling effect work in concert to improve the intrinsic activity of the catalyst. Importantly, the metalloid Ni2P in an intimate combination with the oxygen-defect-rich WO2.83 species endowed the electrocatalyst with high conductivity. Furthermore, the Ni2P/WO2.83 electrocatalyst presented a superhydrophilic nanostructure, ensuring abundant active sites and their accessibility. Benefiting from these attributes, the obtained Ni2P/WO2.83 heterointerface electrocatalyst exhibited excellent activity along with favorable stability for alkaline HER, especially at high current density, surpassing the most reported non-precious catalysts.

5.
Chemistry ; 27(60): 14947-14963, 2021 Oct 25.
Article in English | MEDLINE | ID: mdl-34546603

ABSTRACT

A series of MOFs with a 6-connected spn topology were synthesized (MOF-808-(Zr, Hf), PCN-777-(Zr, Hf), MOF-818-(Zr, Hf)). Through the in situ DRIFTS of NH3 adsorption-desorption, we found that the activated catalyst mainly contains Lewis acid sites. The effects of different organic ligands on the Lewis acid of the Zr6 cluster were analyzed by XPS and NH3 -TPD, and the relative Lewis acidity of the same metal was obtained: PCN-777>MOF-808>MOF-818. In the Py-FTIR results, we confirmed that MOF-818 has a higher acid site density. In the activity test, MOFs with mesoporous structure showed better catalytic activity under normal temperature and pressure. Among them, MOF-818 can still maintain a high degree of crystallinity after catalysis. Finally, we use density functional theory to propose the mechanism of the cycloaddition reaction of carbon dioxide and styrene oxide. The results show that the metal is coordinated with styrene oxide and halogens attack the ß carbon of the epoxide.

6.
Cancer Cell ; 39(7): 945-957.e10, 2021 07 12.
Article in English | MEDLINE | ID: mdl-34019807

ABSTRACT

Tumor-associated macrophages (TAMs) can dampen the antitumor activity of T cells, yet the underlying mechanism remains incompletely understood. Here, we show that C1q+ TAMs are regulated by an RNA N6-methyladenosine (m6A) program and modulate tumor-infiltrating CD8+ T cells by expressing multiple immunomodulatory ligands. Macrophage-specific knockout of an m6A methyltransferase Mettl14 drives CD8+ T cell differentiation along a dysfunctional trajectory, impairing CD8+ T cells to eliminate tumors. Mettl14-deficient C1q+ TAMs show a decreased m6A abundance on and a higher level of transcripts of Ebi3, a cytokine subunit. In addition, neutralization of EBI3 leads to reinvigoration of dysfunctional CD8+ T cells and overcomes immunosuppressive impact in mice. We show that the METTL14-m6A levels are negatively correlated with dysfunctional T cell levels in patients with colorectal cancer, supporting the clinical relevance of this regulatory pathway. Thus, our study demonstrates how an m6A methyltransferase in TAMs promotes CD8+ T cell dysfunction and tumor progression.


Subject(s)
Adenosine/analogs & derivatives , CD8-Positive T-Lymphocytes/immunology , Lymphocyte Activation/immunology , Methyltransferases/metabolism , Methyltransferases/physiology , Neoplasms/pathology , Tumor-Associated Macrophages/metabolism , Adenosine/chemistry , Animals , Carcinoma, Lewis Lung/immunology , Carcinoma, Lewis Lung/metabolism , Carcinoma, Lewis Lung/pathology , Colorectal Neoplasms/immunology , Colorectal Neoplasms/metabolism , Colorectal Neoplasms/pathology , Cytokines/metabolism , Female , Humans , Melanoma, Experimental/immunology , Melanoma, Experimental/metabolism , Melanoma, Experimental/pathology , Methyltransferases/genetics , Mice , Mice, Inbred C57BL , Mice, Knockout , Minor Histocompatibility Antigens/metabolism , Neoplasms/immunology , Neoplasms/metabolism , Receptors, Cytokine/metabolism , Tumor Microenvironment , Tumor-Associated Macrophages/pathology
7.
Mitochondrial DNA B Resour ; 5(1): 541-542, 2020 Jan 14.
Article in English | MEDLINE | ID: mdl-33366638

ABSTRACT

Sarcocheilichthys sinensis (Bleeker), is a small-sized benthopelagic fish with ornamental value. In the present study, the complete mitochondrial genome of S. sinensis was sequenced and determined. The complete mitogenome of S. sinensis was 16,683 bp in length, consisting of 22 tRNA genes, 13 protein-coding genes, 2 rRNA genes, and 2 non-coding regions. The overall base composition of the S. sinensis mitogenome is 30.50% A, 26.28% T, 26.60% C, and 16.61% G, exhibiting obvious AT bias (56.79%). The phylogenetic analysis showed that S. sinensis clustered in genus Sarcocheilichthys. Present study provides useful data to population genetics and conservation biology of Sarcocheilichthys fishes.

8.
ACS Appl Mater Interfaces ; 12(43): 48476-48485, 2020 Oct 28.
Article in English | MEDLINE | ID: mdl-33048536

ABSTRACT

Monometallic and bimetallic MOF-74-M (M = Mn, Co, Ni, Zn, MnCo, MnNi, and MnZn) catalysts were prepared by the solvothermal method for NH3-SCR. XRD, BET, SEM, and EDS-mapping tests indicate the successful synthesis of the MOF-74-M catalyst with uniform distribution of metal elements and large specific surface area, and the morphology is almost hexagonal. Adding Mn element to a single-metal catalyst can enhance activity, which is mainly because of the existence of various valence states of Mn so that it has excellent redox properties; the catalytic activity of water and sulfur resistance tests showed that the catalytic activity of MOF-74-M increases after adding a proper amount of SO2, mainly because of the increase in acidic sites. In situ DRIFTS results indicate that the low-temperature range of MOF-74-MnCo and MOF-74-Mn is dominated by the E-R mechanism and the high-temperature range is dominated by the L-H mechanism. The entire temperature range of MOF-74-Zn is dominated by the L-H mechanism.

9.
Cell Mol Immunol ; 17(2): 143-152, 2020 02.
Article in English | MEDLINE | ID: mdl-30523347

ABSTRACT

The B7-family inducible costimulator (ICOS) activates phosphoinositide-3 kinase (PI3K) and augments calcium mobilization triggered by the T-cell receptor (TCR). We surprisingly found that the entire cytoplasmic domain of ICOS is dispensable for its costimulation of calcium mobilization. This costimulatory function relies on the unique transmembrane domain (TMD) of ICOS, which promotes association with the tyrosine kinase Lck. TMD-enabled Lck association is also required for p85 recruitment to ICOS and subsequent PI3K activation, and Lck underlies both the bystander and costimulatory signaling activity of ICOS. TMD-replaced ICOS, even with an intact cytoplasmic domain, fails to support TFH development or GC formation in vivo. When transplanted onto a chimeric antigen receptor (CAR), the ICOS TMD enhances interactions between T cells and antigen-presenting target cells. Therefore, by revealing an unexpected function of the ICOS TMD, our study offers a new perspective for the understanding and potential application of costimulation biology.


Subject(s)
Inducible T-Cell Co-Stimulator Protein/metabolism , Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/deficiency , Protein Domains/genetics , Receptors, Chimeric Antigen/metabolism , Signal Transduction/genetics , Animals , CD4-Positive T-Lymphocytes/immunology , Calcium/metabolism , Cell Communication/immunology , HEK293 Cells , Humans , Inducible T-Cell Co-Stimulator Protein/genetics , Jurkat Cells , Lymphocyte Specific Protein Tyrosine Kinase p56(lck)/genetics , Mice , Mice, Knockout , Mutant Proteins , Phosphatidylinositol 3-Kinases/metabolism , Protein Domains/immunology , Receptors, Chimeric Antigen/genetics , Signal Transduction/immunology , Transduction, Genetic
10.
Int J Nanomedicine ; 14: 4649-4666, 2019.
Article in English | MEDLINE | ID: mdl-31303753

ABSTRACT

Introduction: Herein, a hyaluronic acid (HA)-coated redox-sensitive chitosan-based nanoparticle, HA(HECS-ss-OA)/GA, was successfully developed for tumor-specific intracellular rapid delivery of gambogic acid (GA). Materials and methods: The redox-sensitive polymer, HECS-ss-OA, was prepared through a well-controlled synthesis procedure with a satisfactory reproducibility and stable resulted surface properties of the assembled cationic micelles. GA was solubilized into the inner core of HECS-ss-OA micelles, while HA was employed to coat outside HECS-ss-OA/GA for CD44-mediated active targeting along with protection from cation-associated in vivo defects. The desirable redox-sensitivity of HA(HECS-ss-OA)/GA was demonstrated by morphology and particle size changes alongside in vitro drug release of nanoparticles in different simulated reducing environments. Results: The results of flow cytometry and confocal microscopy confirmed the HA-receptor mediated cellular uptake and burst drug release in highly reducing cytosol of HA(HECS-ss-OA)/GA. Consequently, HA(HECS-ss-OA)/GA showed the highest apoptosis induction and cytotoxicity over the non-sensitive (HA(HECS-cc-OA)/GA) and HA un-coated (HECS-ss-OA/GA) controls against A549 NSCLC model both in vitro and in vivo. Furthermore, a diminished systemic cytotoxicity was observed in HA(HECS-ss-OA)/GA treated mice compared with those treated by HA un-coated cationic ones and GA solution.


Subject(s)
Chitosan/chemistry , Drug Delivery Systems/methods , Hyaluronic Acid/chemistry , Micelles , Neoplasms/drug therapy , Xanthones/administration & dosage , Xanthones/therapeutic use , A549 Cells , Animals , Antineoplastic Agents/pharmacology , Apoptosis , Calorimetry, Differential Scanning , Cell Proliferation/drug effects , Cell Survival/drug effects , Chitosan/chemical synthesis , Humans , Hyaluronic Acid/chemical synthesis , Mice, Inbred BALB C , Mice, Nude , Nanoparticles/chemistry , Neoplasms/pathology , Oxidation-Reduction , Propionates/chemical synthesis , Propionates/chemistry , Proton Magnetic Resonance Spectroscopy , Reproducibility of Results , Tissue Distribution/drug effects , Tumor Burden/drug effects , Xanthones/pharmacology
11.
Nature ; 568(7751): E3, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30911170

ABSTRACT

In this Letter, a citation to 'Fig. 1e' has been corrected to 'Fig. 1d' in the sentence starting "By contrast, the anti-tumour response…". This has been corrected online.

12.
Nature ; 566(7743): 270-274, 2019 02.
Article in English | MEDLINE | ID: mdl-30728504

ABSTRACT

There is growing evidence that tumour neoantigens have important roles in generating spontaneous antitumour immune responses and predicting clinical responses to immunotherapies1,2. Despite the presence of numerous neoantigens in patients, complete tumour elimination is rare, owing to failures in mounting a sufficient and lasting antitumour immune response3,4. Here we show that durable neoantigen-specific immunity is regulated by mRNA N6-methyadenosine (m6A) methylation through the m6A-binding protein YTHDF15. In contrast to wild-type mice, Ythdf1-deficient mice show an elevated antigen-specific CD8+ T cell antitumour response. Loss of YTHDF1 in classical dendritic cells enhanced the cross-presentation of tumour antigens and the cross-priming of CD8+ T cells in vivo. Mechanistically, transcripts encoding lysosomal proteases are marked by m6A and recognized by YTHDF1. Binding of YTHDF1 to these transcripts increases the translation of lysosomal cathepsins in dendritic cells, and inhibition of cathepsins markedly enhances cross-presentation of wild-type dendritic cells. Furthermore, the therapeutic efficacy of PD-L1 checkpoint blockade is enhanced in Ythdf1-/- mice, implicating YTHDF1 as a potential therapeutic target in anticancer immunotherapy.


Subject(s)
Adenosine/analogs & derivatives , Adenosine/metabolism , Dendritic Cells/immunology , Neoplasms/immunology , RNA, Messenger/metabolism , RNA-Binding Proteins/metabolism , Animals , Antigen Presentation/immunology , Antigens, Neoplasm/immunology , Antigens, Neoplasm/metabolism , B7-H1 Antigen/metabolism , Binding Sites , CD8-Positive T-Lymphocytes/immunology , Cathepsins/antagonists & inhibitors , Cathepsins/biosynthesis , Cathepsins/genetics , Cross-Priming/immunology , Dendritic Cells/enzymology , Female , Humans , Methylation , Mice , Mice, Inbred C57BL , Neoplasms/therapy , Protein Biosynthesis , Proteins/genetics , RNA, Messenger/chemistry , RNA-Binding Proteins/genetics , Transcriptome/genetics
13.
ACS Appl Mater Interfaces ; 10(47): 40509-40522, 2018 Nov 28.
Article in English | MEDLINE | ID: mdl-30372026

ABSTRACT

A series of samples with the precursor's molar ratio of {KMn8O16}/{CuFe2O4} = 0, 0.008, 0.010, 0.016, and 0.020 were successfully synthesized for selective catalytic reduction of NO by CO. The physicochemical properties of all samples were studied in detail by combining the means of X-ray photoelectron spectroscopy, H2-temperature-programmed reduction, scanning electron microscopy mapping, X-ray diffraction (XRD), N2 physisorption (Brunauer-Emmett-Teller), NO + CO model reaction, and in situ Fourier transform infrared spectroscopy techniques. The results show that three phases of γ-Fe2O3, CuFe2O4, and CuO, which have strong synergistic interaction, coexist in this catalyst system, and different phases play a leading role in different temperature ranges. Mn species are highly dispersed in the three-phase coexisting system in the form of Mn2+, Mn3+, and Mn4+. Because of the strong interaction between Mn2+ and Fe species, a small amount of Cu2+ precipitates from CuFe2O4 and grows along the CuO(110) plane, which has better catalytic performance. Mn3+ can inhibit the conversion of γ-Fe2O3 to α-Fe2O3 at high temperature and then increases the high-temperature activity. The synergistic effect between Mn4+ and the surfaces of three phases generates active oxygen species Cu2+-O-Mn4+ and Mn4+-O-Fe3+, which can be more easily reduced to some synergistic oxygen vacancies during the reaction. Furthermore, the formed synergistic oxygen vacancies can promote the dissociation of NO and are also propitious to the transfer of oxygen species. All of these factors make the appropriate manganese-modified three-phase coexisting system have better catalytic activity than the manganese-free catalyst, making NO conversion rate reach 100% at around 250 °C and maintain to 1000 °C. Combining comprehensive analysis of various characterization results and in situ infrared as well as XRD results in the equilibrium state, a new possible NO + CO model reaction mechanism was temporarily proposed to further understand the catalytic processes.

14.
J Phys Chem A ; 122(9): 2319-2328, 2018 Mar 08.
Article in English | MEDLINE | ID: mdl-29457723

ABSTRACT

The H+ + H2 reaction and its isotopic variants as the simplest triatomic ion-molecule reactive system have been attracting much interests, however there are few studies on the titled reaction at state-to-state level until recent years. In this work, accurate state-to-state quantum dynamics studies of the titled reaction have been carried out by a reactant Jacobi coordinate-based time-dependent wave packet approach on diabatic potential energy surfaces constructed by Kamisaka et al. Product ro-vibrational state-resolved information has been calculated for collision energies up to 0.2 eV with maximal total angular momentum J = 40. The necessity of including all K-component for accounting the Coriolis coupling for the reaction has been illuminated. Competitions between the two product channels, (D+ + HD' → D'+ + HD and D+ + HD' → H+ + DD') were investigated. Total integral cross sections suggest that resonances enhance the reactivity of channel D+ + HD'→ H+ + DD', however, resonances depress the reactivity of the another channel D+ + HD' → D'+ + HD. The structures of the differential cross sections are complicated and depend strongly on collision energies of the two channels and also on the product rotational states. All of the product ro-vibrational state-resolved differential cross sections for this reaction do not exhibit rigorous backward-forward symmetry which may indicate that the lifetimes of the intermediate resonance complexes should not be that long. The dynamical observables of this deuterated isotopic reaction are quite different from the reaction of H+ + H2 → H2 + H+ reported previously.

15.
RSC Adv ; 8(13): 7110-7122, 2018 Feb 09.
Article in English | MEDLINE | ID: mdl-35540327

ABSTRACT

In this work, mesoporous Ni-Co composite oxides were synthesized by a facile liquid-precipitation method without the addition of surfactant, and their ability to catalyse a low temperature CO oxidation reaction was investigated. To explore the effect of the synergetic interaction between Ni and Co on the physicochemical properties and catalytic performance of these catalysts, the as-prepared samples were characterized using XRF, XRD, LRS, N2-physisorption (BET), SEM, TEM, XPS, H2-TPR, O2-TPD and in situ DRIFTS characterization techniques. The results are as follows: (1) the doping of cobalt can reduces the size of NiO, thus massive amorphous NiO have formed and highly dispersed on the catalyst surface, resulting in the formation of abundant surface Ni2+ ions; (2) Ni2+ ions partially substitute Co3+ ions to form a Ni-Co spinel solid solution, generating an abundance of surface oxygen vacancies, which are vital for CO oxidation; (3) the Ni0.8Co0.2 catalyst exhibits the highest catalytic activity and a satisfactory stability for CO oxidation, whereas a larger cobalt content results in a decrease in activity, suggesting that the amorphous NiO phase is the dominant active phase instead of Co3O4 for CO oxidation; (4) the introduction of Co can alter the morphology of catalyst from plate-like to flower-like and then to dense granules. This morphological variation is related to the textural properties and catalytic performance of the catalysts. Lastly, a possible mechanism for CO oxidation reaction is tentatively proposed.

16.
J Control Release ; 243: 54-68, 2016 12 10.
Article in English | MEDLINE | ID: mdl-27702595

ABSTRACT

Co-delivery systems capable of transporting hydrophobic chemotherapeutics and hydrophilic siRNA to the same cell population with simultaneous burst release of both drugs to maximize synergistic anticancer efficacy remains elusive. In this light, a multifunctional nanoparticle (HA-PSR) consisting of a redox-sensitive core and detachable crosslinked hyaluronic acid (HA) shell was developed. Octyl modified PEI containing disulfide linkages (PSR) were synthesized as the core materials for co-encapsulation of chemotherapeutics and siRNA, while a HAase-sensitive thiolated HA (HA-SH) was collaboratively assembled to the anionic shell for CD44-mediated active targeting along with enhanced and detachable protection for drug loaded inner cores. Resultantly, HA de-protected redox-sensitive inner cores achieved co-burst release of both cargoes when triggered by glutathione (GSH) rich environments in cytoplasm. Results of in-vivo and in-vitro testing indicated successful co-encapsulation of hydrophobic drugs and hydrophilic siRNA with adjustable ratios. Selective delivery to CD44 overexpressing tumors was achieved through passive and active targeting, followed by HAase-triggered HA de-shielding and GSH-triggered burst release of both cargos. Rapid intracellular trafficking maximized synergistic cytotoxicities of chemotherapeutics and siRNA for remarkable tumor inhibition in a xenograft animal tumor model. Consequently, the HA-PSR nanoparticle holds great potential for combined chemotherapeutics/siRNA treatment in cancer with maximized synergistic antitumor efficacy.


Subject(s)
Antineoplastic Agents/administration & dosage , Hyaluronan Receptors/metabolism , Hyaluronic Acid/chemistry , Nanoparticles , Animals , Antineoplastic Agents/chemistry , Antineoplastic Agents/pharmacology , Chemistry, Pharmaceutical/methods , Drug Carriers/chemistry , Drug Delivery Systems , Drug Synergism , Female , Humans , Hydrophobic and Hydrophilic Interactions , Mice, Inbred BALB C , Mice, Nude , Neoplasms/drug therapy , Neoplasms/pathology , Polyethyleneimine/chemistry , RNA, Small Interfering/administration & dosage , THP-1 Cells , Xenograft Model Antitumor Assays
17.
Chem Asian J ; 11(15): 2144-56, 2016 Aug 05.
Article in English | MEDLINE | ID: mdl-27435470

ABSTRACT

This work is mainly focused on investigating the effects of different doped metal cations on the formation of Ce20 M1 Ox (M=Zr, Cr, Mn, Fe, Co, Sn) composite oxides and their physicochemical and catalytic properties for NO reduction by CO as a model reaction. The obtained samples were characterized by using N2 physisorption, X-ray diffraction, laser Raman spectroscopy, UV/Vis diffuse reflectance spectroscopy, inductively coupled plasma atomic emission spectroscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by hydrogen and by oxygen (H2 -TPR and O2 -TPD), in situ diffuse reflectance infrared Fourier transform spectroscopy, and the NO+CO model reaction. The results imply that the introduction of M(x+) into the lattice of CeO2 increases the specific surface area and pore volume, especially for variable valence metal cations, and enhances the catalytic performance to a great extent. In this regard, increases in the oxygen vacancies, reduction properties, and chemisorbed O2 (-) (and/or O(-) ) species of these Ce20 M1 Ox composite oxides (M refers to variable valence metals) play significant roles in this reaction. Among the samples, Ce20 Cr1 Ox exhibited the best catalytic performance, mainly because it has the best reducibility and more chemisorbed oxygen, and significant reasons for these attributes may be closely related to favorable synergistic interactions of the vacancies and near-surface Ce(3+) and Cr(3+) . Finally, a possible reaction mechanism was tentatively proposed to understand the reactions.

18.
Sci Rep ; 6: 23382, 2016 Mar 18.
Article in English | MEDLINE | ID: mdl-26987306

ABSTRACT

The investigation on the modification of NaY zeolite on LaHY and AEHY (AE refers Ca and Sr and the molar ratio of Ca and Sr is 1:1) zeolites was proformed by XRD, N2-physisorption (BET), XRF, XPS, NH3-TPD, Py-IR, hydrothermal stability, and catalytic cracking test. These results indicate that HY zeolite with ultra low content Na can be obtained from NaY zeolite through four exchange four calcination method. The positioning capability of La(3+) in sodalite cage is much better than that of AE(2+) and about 12 La(3+) can be well coordinated in sodalite cages of one unit cell of Y zeolite. Appropriate acid amount and strength favor the formation of propylene and La(3+) is more suitable for the catalytic cracking of cyclohexane than that of AE(2+). Our results not only elaborate the variation of the strong and weak acid sites as well as the Brönsted and Lewis acid sites with the change of exchanged ion content but also explore the influence of hydrothermal aging of LaHY and AEHY zeolites and find the optimum ion exchange content for the most reserved acid sites. At last, the coordination state and stabilization of ion exchanged Y zeolites were discussed in detail.

19.
Int J Nanomedicine ; 10: 7397-412, 2015.
Article in English | MEDLINE | ID: mdl-26715846

ABSTRACT

Clinically, paclitaxel (PTX) is one of most commonly prescribed therapies against a wide range of solid neoplasms. Despite its success, the clinical applicability of PTX (Taxol) is severely hampered by systemic toxicities induced by Cremophor EL. While attempts to bypass the need for Cremophor EL have been developed through platforms such as Abraxane, nab relies heavily on the use of organic solvents, namely, chloroform. The toxicity introduced by residual chloroform poses a potential risk to patient health. To mitigate the toxicities of toxic organic solvent-based manufacture methods, we have designed a method for the formulation of PTX nanosuspensions (PTX-PEG [polyethylene glycol]-HSA [human serum albumin]) that eliminates the dependence on toxic organic solvents. Coined the solid-dispersion technology, this technique permits the dispersion of PTX into PEG skeleton without the use of organic solvents or Cremophor EL as a solubilizer. Once the PTX-PEG dispersion is complete, the dispersion can be formulated with HSA into nanosuspensions suitable for intravenous administration. Additionally, the incorporation of PEG permits the prolonged circulation through the steric stabilization effect. Finally, HSA-mediated targeting permits active receptor-mediated endocytosis for enhanced tumor uptake and reduced side effects. By eliminating the need for both Cremophor EL and organic solvents while simultaneously increasing antitumor efficacy, this method provides a superior alternative to currently accepted methods for PTX delivery.


Subject(s)
Albumin-Bound Paclitaxel/chemistry , Antineoplastic Agents/chemistry , Chemistry, Pharmaceutical/methods , Nanomedicine , Polyethylene Glycols/chemistry , Albumin-Bound Paclitaxel/pharmacology , Animals , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Green Chemistry Technology , Humans , Mice , Micelles , Suspensions
20.
Phys Chem Chem Phys ; 17(24): 16092-109, 2015 Jun 28.
Article in English | MEDLINE | ID: mdl-26030478

ABSTRACT

This work is mainly focused on the investigation of the influence of the amount of a few CeO2 on the physicochemical and catalytic properties of CeO2-doped TiO2 catalysts for NO reduction by a CO model reaction. The obtained samples were characterized by means of XRD, N2-physisorption (BET), LRS, UV-vis DRS, XPS, (O2, CO, and NO)-TPD, H2-TPR, in situ FT-IR, and a NO + CO model reaction. These results indicate that a small quantity of CeO2 doping into the TiO2 support will cause an obvious change in the properties of the catalyst and the TC-60 : 1 (the TiO2/CeO2 molar ratio is 60 : 1) support exhibits the most extent of lattice expansion, which indicates that the band lengths of Ce-O-Ti are longer than other TC (the solid solution of TiO2 and CeO2) samples, probably contributing to larger structural distortion and disorder, more defects and oxygen vacancies. Copper oxide species supported on TC supports are much easier to be reduced than those supported on the pure TiO2 and CeO2 surface-modified TiO2 supports. Furthermore, the Cu/TC-60 : 1 catalyst shows the highest activity and selectivity due to more oxygen vacancies, higher mobility of surface and lattice oxygen at lower temperature (which contributes to the regeneration of oxygen vacancies, and the best reducing ability), the most content of Cu(+), and the strongest synergistic effect between Ti(3+), Ce(3+) and Cu(+). On the other hand, the CeO2 doping into TiO2 promotes the formation of a Cu(+)/Cu(0) redox cycle at high temperatures, which has a crucial effect on N2O reduction. Finally, in order to further understand the nature of the catalytic performances of these samples, taking the Cu/TC-60 : 1 catalyst as an example, a possible reaction mechanism is tentatively proposed.

SELECTION OF CITATIONS
SEARCH DETAIL
...