RESUMO
Developing highly efficient and carbon monoxide (CO)-tolerant platinum (Pt) catalysts for the formic acid oxidation reaction (FAOR) is vital for direct formic acid fuel cells (DFAFCs), yet it is challenging due to the high energy barrier of direct intermediates (HCOO* and COOH*) as well as the CO poisoning issues associated with Pt alloy catalysts. Here we present a versatile biphasic strategy by creating a hexagonal/cubic crystalline-phase-synergistic PtPb/C (h/c-PtPb/C) catalyst to tackle the aforementioned issues. Detailed investigations reveal that h/c-PtPb/C can simultaneously facilitate the adsorption of direct intermediates while inhibiting CO adsorption, thereby significantly improving the activation and CO spillover. As a result, h/c-PtPb/C showcases an outstanding FAOR activity of 8.1 A mgPt-1, which is 64.5 times higher than that of commercial Pt/C and significantly surpasses monophasic PtPb. Moreover, the h/c-PtPb/C-based membrane electrode assembly exhibits an exceptional peak power density of 258.7 mW cm-2 for practical DFAFC applications.
RESUMO
Amorphous nanomaterials have drawn extensive attention owing to their unique features, while amorphization on noble metal nanomaterials still remains formidably challenging. Herein, we demonstrate a universal strategy to synthesize amorphous Pd-based nanomaterials from unary to quinary metals through the introduction of phosphorus (P). The amorphous Pd-based nanoparticles (NPs) exhibit generally promoted oxygen reduction reaction (ORR) activity and durability compared with their crystalline counterparts. Significantly, the quinary P-PdCuNiInSn NPs, benefiting from the amorphous structure and multimetallic component effect, exhibit mass activities as high as 1.04 A mgPd-1 and negligible activity decays of 1.8% among the stability tests, which are much better than values for original Pd NPs (0.134 A mgPd-1 and 28.4%). Experimental and theoretical analyses collectively reveal that the synergy of P-induced amorphization and the expansion of metallic components can considerably lower the free energy changes in the rate-determined step, thereby explaining the positive correlation with the catalytic activity.
RESUMO
The determination of catalytically active sites is crucial for understanding the catalytic mechanism and providing guidelines for the design of more efficient catalysts. However, the complex structure of supported metal nanocatalysts (e.g., support, metal surface, and metal-support interface) still presents a big challenge. In particular, many studies have demonstrated that metal-support interfaces could also act as the primary active sites in catalytic reactions, which is well elucidated in oxide-supported metal nanocatalysts but is rarely reported in carbon-supported metal nanocatalysts. Here, we fill the above gap and demonstrate that metal-sulfur interfaces in sulfur-doped carbon-supported metal nanocatalysts are the primary active sites for several catalytic hydrogenation reactions. A series of metal nanocatalysts with similar sizes but different amounts of metal-sulfur interfaces were first constructed and characterized. Taking Ir for quinoline hydrogenation as an example, it was found that their catalytic activities were proportional to the amount of the Ir-S interface. Further experiments and density functional theory (DFT) calculations suggested that the adsorption and activation of quinoline occurred on the Ir atoms at the Ir-S interface. Similar phenomena were found in p-chloronitrobenzene hydrogenation over the Pt-S interface and benzoic acid hydrogenation over the Ru-S interface. All of these findings verify the predominant activity of metal-sulfur interfaces for catalytic hydrogenation reactions and contribute to the comprehensive understanding of metal-support interfaces in supported nanocatalysts.
RESUMO
Superconductivity was discovered in (InSe2)xNbSe2. The materials are crystallized in a unique layered structure where bonded InSe2 layers are intercalated into the van der Waals gaps of 2H-phase NbSe2. The (InSe2)0.12NbSe2 superconductor exhibits a superconducting transition at 11.6 K and critical current density of 8.2 × 105 A/cm2. Both values are the highest among all transition metal dichalcogenide superconductors at ambient pressure. The present finding provides an ideal material platform for further investigation of superconducting-related phenomena in transition metal dichalcogenides.
RESUMO
Heterophase nanomaterials have sparked significant research interest in catalysis due to their distinctive properties arising from synergistic effects of different components and the formed phase boundary. However, challenges persist in the controlled synthesis of heterophase intermetallic compounds (IMCs), primarily due to the lattice mismatch of distinct crystal phases and the difficulty in achieving precise control of the phase transitions. Herein, orthorhombic/cubic Ru2Ge3/RuGe IMCs with engineered boundary architecture are synthesized and anchored on the reduced graphene oxide. The Ru2Ge3/RuGe IMCs exhibit excellent hydrogen evolution reaction (HER) performance with a high current density of 1000 mA cm-2 at a low overpotential of 135 mV. The presence of phase boundaries enhances charge transfer and improves the kinetics of water dissociation while optimizing the processes of hydrogen adsorption/desorption, thus boosting the HER performance. Moreover, an anion exchange membrane electrolyzer is constructed using Ru2Ge3/RuGe as the cathode electrocatalyst, which achieves a current density of 1000 mA cm-2 at a low voltage of 1.73 V, and the activity remains virtually undiminished over 500 h.
RESUMO
Electrocatalytic nitrate (NO3-) reduction reaction (NO3RR) holds great potential for the conversion of NO3- contaminants into valuable NH3 in a sustainable method. Unfortunately, the nonequilibrium adsorption of intermediates and sluggish multielectron transfer have detrimental impacts on the electrocatalytic performance of the NO3RR, posing obstacles to its practical application. Herein, we initially screen the adsorption energies of three key intermediates, i.e., *NO3, *NO, and *H2O, along with the d-band centers on 21 types of transition metal (IIIV and IB)-Sb/Bi-based intermetallic compounds (IMCs) as electrocatalysts. The results reveal that hexagonal CoSb IMCs possess the optimal adsorption equilibrium for key intermediates and exhibit outstanding electrocatalytic NO3RR performance with a Faradaic efficiency of 96.3%, a NH3 selectivity of 89.1%, and excellent stability, surpassing the majority of recently reported NO3RR electrocatalysts. Moreover, the integration of CoSb IMCs/C into a novel Zn-NO3- battery results in a high power density of 11.88 mW cm-2.
RESUMO
Metal silicide/Si photoelectrodes have demonstrated significant potential for application in photoelectrochemical (PEC) water splitting to produce H2. To achieve an efficient and economical hydrogen evolution reaction (HER), a paramount consideration lies in attaining exceptional catalytic activity on the metal silicide surface with minimal use of noble metals. Here, this study presents the design and construction of a novel Ni0.95Pt0.05Si/p-Si photocathode. Dopant segregation is used to achieve a Schottky barrier height as high as 1.0 eV and a high photovoltage of 420 mV. To achieve superior electrocatalytic activity for HER, a dissolution-induced surface reconstruction (SR) strategy is proposed to in situ convert surface Ni0.95Pt0.05Si to highly active Pt2Si. The resulting SR Ni0.95Pt0.05Si/p-Si photocathode exhibits excellent HER performance with an onset potential of 0.45 V (vs RHE) and a high maximum photocurrent density of 40.5 mA cm-2 and a remarkable applied bias photon-to-current efficiency (ABPE) of 5.3% under simulated AM 1.5 (100 mW cm-2) illumination. The anti-corrosion silicide layer effectively protects Si, ensuring excellent stability of the SR Ni0.95Pt0.05Si/p-Si photoelectrode. This study highlights the potential for achieving efficient PEC HER using bimetallic silicide/Si photocathodes with reduced Pt consumption, offering an auspicious perspective for the cost-effective conversion of solar energy to chemical energy.
RESUMO
Pressure overload-induced pathological cardiac hypertrophy eventually leads to heart failure (HF). Unfortunately, lack of effective targeted therapies for HF remains a challenge in clinical management. Mixed-lineage leukemia 4 (MLL4) is a member of the SET family of histone methyltransferase enzymes, which possesses histone H3 lysine 4 (H3K4)-specific methyltransferase activity. However, whether and how MLL4 regulates cardiac function is not reported in adult HF. Here we report that MLL4 is required for endoplasmic reticulum (ER) stress homeostasis of cardiomyocytes and protective against pressure overload-induced cardiac hypertrophy and HF. We observed that MLL4 is increased in the heart tissue of HF mouse model and HF patients. The cardiomyocyte-specific deletion of Mll4 (Mll4-cKO) in mice leads to aggravated ER stress and cardiac dysfunction following pressure overloading. MLL4 knockdown neonatal rat cardiomyocytes (NRCMs) also display accelerated decompensated ER stress and hypertrophy induced by phenylephrine (PE). The combined analysis of Cleavage Under Targets and Tagmentation sequencing (CUT&Tag-seq) and RNA sequencing (RNA-seq) data reveals that, silencing of Mll4 alters the chromatin landscape for H3K4me1 modification and gene expression patterns in NRCMs. Interestingly, the deficiency of MLL4 results in a marked reduction of H3K4me1 and H3K27ac occupations on Thrombospondin-4 (Thbs4) gene loci, as well as Thbs4 gene expression. Mechanistically, MLL4 acts as a transcriptional activator of Thbs4 through mono-methylation of H3K4 and further regulates THBS4-dependent ER stress response, ultimately plays a role in HF. Our study indicates that pharmacologically targeting MLL4 and ER stress might be a valid therapeutic approach to protect against cardiac hypertrophy and HF.
Assuntos
Estresse do Retículo Endoplasmático , Insuficiência Cardíaca , Histona-Lisina N-Metiltransferase , Camundongos Endogâmicos C57BL , Miócitos Cardíacos , Animais , Insuficiência Cardíaca/metabolismo , Insuficiência Cardíaca/genética , Insuficiência Cardíaca/etiologia , Histona-Lisina N-Metiltransferase/metabolismo , Histona-Lisina N-Metiltransferase/genética , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/efeitos dos fármacos , Estresse do Retículo Endoplasmático/efeitos dos fármacos , Masculino , Humanos , Camundongos Knockout , Ratos , Camundongos , Células Cultivadas , Cardiomegalia/metabolismo , Cardiomegalia/genética , Ratos Sprague-Dawley , TrombospondinasRESUMO
Bismuth-based materials have emerged as promising catalysts in the electrocatalytic reduction of CO2 to formate. However, the reasons for the reconstruction of Bi-based precursors to form bismuth nanosheets are still puzzling, especially the formation of defective bismuth sites. Herein, we prepare bismuth nanosheets with vacancy-rich defects (V-Bi NS) by rapidly reconstructing Bi19Cl3S27 under negative potential. Theoretical analysis reveals that the introduction of chlorine induces the generation of intrinsic electric field in the precursor, thereby increasing the electron transfer rate and further promoting the metallization of trivalent bismuth. Meanwhile, experimental tests verify that Bi19Cl3S27 has a faster reconstruction rate than Bi2S3. The formed V-Bi NS exhibits up to 96 % HCOO- Faraday efficiency and 400â mA cm-2 HCOO- partial current densities, and its electrochemical active surface area normalized formate current density and yield are 2.2â times higher than those of intact bismuth nanosheets (I-Bi NS). Density functional theory calculations indicate that bismuth vacancies with electron-rich aggregation reduce the activation energy of CO2 to *CO2 - radicals and stabilize the adsorption of the key intermediate *OCHO, thus facilitating the reaction kinetics of formate production.
RESUMO
Constructing amorphous/intermetallic (A/IMC) heterophase structures by breaking the highly ordered IMC phase with disordered amorphous phase is an effective way to improve the electrocatalytic performance of noble metal-based IMC electrocatalysts because of the optimized electronic structure and abundant heterophase boundaries as active sites. In this study, we report the synthesis of ultrathin A/IMC PtPbBi nanosheets (NSs) for boosting hydrogen evolution reaction (HER) and alcohol oxidation reactions. The resulting A/IMC PtPbBi NSs exhibit a remarkably low overpotential of only 25â mV at 10â mA cm-2 for the HER in an acidic electrolyte, together with outstanding stability for 100â h. In addition, the PtPbBi NSs show high mass activities for methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), which are 13.2 and 14.5 times higher than those of commercial Pt/C, respectively. Density functional theory calculations demonstrate that the synergistic effect of amorphous/intermetallic components and multimetallic composition facilitate the electron transfer from the catalyst to key intermediates, thus improving the catalytic activity of MOR. This work establishes a novel pathway for the synthesis of heterophase two-dimensional nanomaterials with high electrocatalytic performance across a wide range of electrochemical applications.
RESUMO
As representative extended planar defects, crystallographic shear (CS) planes, namely Wadsley defects, play an important role in modifying the physical and chemical properties of metal oxides. Although these special structures have been intensively investigated for high-rate anode materials and catalysts, it is still experimentally unclear how the CS planes form and propagate at the atomic scale. Here, the CS plane evolution in monoclinic WO3 is directly imaged via in situ scanning transmission electron microscope. It is found that the CS planes nucleate preferentially at the edge step defects and proceed by the cooperative migration of WO6 octahedrons along particular crystallographic orientations, passing through a series of intermediate states. The local reconstruction of atomic columns tends to form (102) CS planes featured with four edge-sharing octahedrons in preference to the (103) planes, which matches well with the theoretical calculations. Associated with the structure evolution, the sample undergoes a semiconductor-to-metal transition. In addition, the controlled growth of CS planes and V-shaped CS structures can be achieved by artificial defects for the first time. These findings enable an atomic-scale understanding of CS structure evolution dynamics.
RESUMO
RATIONALE: Previous translational studies implicate plasma extracellular microRNA-30d (miR-30d) as a biomarker in left ventricular remodeling and clinical outcome in heart failure (HF) patients, although precise mechanisms remain obscure. OBJECTIVE: To investigate the mechanism of miR-30d-mediated cardioprotection in HF. METHODS AND RESULTS: In rat and mouse models of ischemic HF, we show that miR-30d gain of function (genetic, lentivirus, or agomiR-mediated) improves cardiac function, decreases myocardial fibrosis, and attenuates cardiomyocyte (CM) apoptosis. Genetic or locked nucleic acid-based knock-down of miR-30d expression potentiates pathological left ventricular remodeling, with increased dysfunction, fibrosis, and cardiomyocyte death. RNA sequencing of in vitro miR-30d gain and loss of function, together with bioinformatic prediction and experimental validation in cardiac myocytes and fibroblasts, were used to identify and validate direct targets of miR-30d. miR-30d expression is selectively enriched in cardiomyocytes, induced by hypoxic stress and is acutely protective, targeting MAP4K4 (mitogen-associate protein kinase 4) to ameliorate apoptosis. Moreover, miR-30d is secreted primarily in extracellular vesicles by cardiomyocytes and inhibits fibroblast proliferation and activation by directly targeting integrin α5 in the acute phase via paracrine signaling to cardiac fibroblasts. In the chronic phase of ischemic remodeling, lower expression of miR-30d in the heart and plasma extracellular vesicles is associated with adverse remodeling in rodent models and human subjects and is linked to whole-blood expression of genes implicated in fibrosis and inflammation, consistent with observations in model systems. CONCLUSIONS: These findings provide the mechanistic underpinning for the cardioprotective association of miR-30d in human HF. More broadly, our findings support an emerging paradigm involving intercellular communication of extracellular vesicle-contained miRNAs (microRNAs) to transregulate distinct signaling pathways across cell types. Functionally validated RNA biomarkers and their signaling networks may warrant further investigation as novel therapeutic targets in HF.
Assuntos
MicroRNAs/metabolismo , Infarto do Miocárdio/metabolismo , Miocárdio/metabolismo , Comunicação Parácrina , Função Ventricular Esquerda , Remodelação Ventricular , Animais , Apoptose , Células Cultivadas , Modelos Animais de Doenças , Vesículas Extracelulares/genética , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/patologia , Fibroblastos/metabolismo , Fibroblastos/patologia , Fibrose , Regulação da Expressão Gênica , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , MicroRNAs/genética , Infarto do Miocárdio/genética , Infarto do Miocárdio/patologia , Infarto do Miocárdio/fisiopatologia , Miocárdio/patologia , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/patologia , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/metabolismo , Ratos Sprague-Dawley , Ratos Transgênicos , Transdução de Sinais , Quinase Induzida por NF-kappaBRESUMO
PURPOSE: This study aimed to translate and culturally adapt the immune checkpoint modulator (ICM) subscale of the Functional Assessment of Cancer Therapy-Immune Checkpoint Modulator (FACT-ICM) scale and to validate the FACT-ICM scale in Chinese cancer patients receiving immune checkpoint inhibitors (ICIs) treatment. METHODS: In total, 354 cancer patients treated with ICIs were included in our cross-sectional study including 2 phases. Firstly, the ICM subscale was translated and culturally adapted by standardized procedures. Then the FACT-ICM scale was validated, which included item analysis, content validity, floor and ceiling effects, internal consistency reliability, test-retest reliability, construct validity, convergent/divergent validity, and known-group validity. RESULTS: The content validity indexes at the item and scale level of the ICM subscale were greater than 0.8. No floor and ceiling effects were found. The Cronbach's α and McDonald's omega coefficients of the simplified Chinese version of the FACT-ICM scale were 0.935 and 0.936, and the intraclass correlation coefficient was 0.833 (95% confidence interval: 0.574-0.940). Confirmatory factor analysis confirmed the 5-subscale structure of the simplified Chinese version of the FACT-ICM scale (χ2/df = 2.144, RMSEA = 0.057, SRMR = 0.072, and CFI = 0.848). Convergent and divergent validity further supported the construct validity of the simplified Chinese version of the FACT-ICM scale. The known-group validity of the simplified Chinese version of the FACT-ICM scale was confirmed in patients with different physical statuses. CONCLUSIONS: The simplified Chinese version of the FACT-ICM scale is a valid and reliable instrument and can be used in clinical practice and research on cancer patients receiving ICIs treatment.
Assuntos
Neoplasias , Qualidade de Vida , Humanos , Inquéritos e Questionários , Reprodutibilidade dos Testes , Estudos Transversais , Psicometria/métodos , Qualidade de Vida/psicologia , Neoplasias/tratamento farmacológico , ChinaRESUMO
The chronic wound represents a serious disease characterized by a failure to heal damaged skin and surrounding soft tissue. Mesenchymal stem cells (MSCs) derived from adipose tissue (ADSCs) are a promising therapeutic strategy, but their heterogeneity may result in varying or insufficient therapeutic capabilities. In this study, we discovered that all ADSCs populations expressed platelet-derived growth factor receptor ß (PDGFR-ß), while the expression level decreased dynamically with passages. Thus, using a CRISPRa-based system, we endogenously overexpressed PDGFR-ß in ADSCs. Moreover, a series of in vivo and in vitro experiments were conducted to determine the functional changes in PDGFR-ß activation ADSCs (AC-ADSCs) and to investigate the underlying mechanisms. With the activation of PDGFR-ß, AC-ADSCs exhibited enhanced migration, survival, and paracrine capacity relative to control ADSCs (CON-ADSCs). In addition, the secretion components of AC-ADSCs contained more pro-angiogenic factors and extracellular matrix-associated molecules, which promoted the function of endothelial cells (ECs) in vitro. Additionally, in in vivo transplantation experiments, the AC-ADSCs transplantation group demonstrated improved wound healing rates, stronger collagen deposition, and angiogenesis. Consequently, our findings revealed that PDGFR-ß overexpression enhanced the migration, survival, and paracrine capacity of ADSCs and improved therapeutic effects after transplantation to diabetic mice.
Assuntos
Diabetes Mellitus Experimental , Células-Tronco Mesenquimais , Camundongos , Animais , Células Endoteliais , Diabetes Mellitus Experimental/terapia , Diabetes Mellitus Experimental/metabolismo , Cicatrização , Células-Tronco Mesenquimais/metabolismo , Matriz Extracelular , Tecido AdiposoRESUMO
The direct electrochemical nitric oxide reduction reaction (NORR) is an attractive technique for converting NO into NH3 with low power consumption under ambient conditions. Optimizing the electronic structure of the active sites can greatly improve the performance of electrocatalysts. Herein, we prepare body-centered cubic RuGa intermetallic compounds (i.e., bcc RuGa IMCs) via a substrate-anchored thermal annealing method. The electrocatalyst exhibits a remarkable NH4 + yield rate of 320.6â µmol h-1 mg-1 Ru with the corresponding Faradaic efficiency of 72.3 % at very low potential of -0.2â V vs. reversible hydrogen electrode (RHE) in neutral media. Theoretical calculations reveal that the electron-rich Ru atoms in bcc RuGa IMCs facilitate the adsorption and activation of *HNO intermediate. Hence, the energy barrier of the potential-determining step in NORR could be greatly reduced.
RESUMO
Histone methylation is one of the key post-translational modifications that plays a critical role in various heart diseases, including diabetic cardiomyopathy. A great deal of evidence has shown that histone methylation is closely related to hyperglycemia, insulin resistance, lipid and advanced glycation end products deposition, inflammatory and oxidative stress, endoplasmic reticulum stress and cell apoptosis, and these pathological factors play an important role in the pathogenesis of diabetic cardiomyopathy. In order to provide a novel theoretical basis and potential targets for the treatment of diabetic cardiomyopathy from the perspective of epigenetics, this review discussed and elucidated the association between histone methylation and the pathogenesis of diabetic cardiomyopathy in details.
Assuntos
Diabetes Mellitus , Cardiomiopatias Diabéticas , Cardiomiopatias Diabéticas/etiologia , Cardiomiopatias Diabéticas/patologia , Histonas , Humanos , Metilação , Estresse Oxidativo , Processamento de Proteína Pós-TraducionalRESUMO
Two biologically inspired tetranuclear nickel complexes [Ni4(L-H)4(CH3COO)3]·Cl (1) and [Ni4(L-H)4(CH3COO)4]·2CH3OH (2) (L = di(pyridin-2-yl)methanediol) have been synthesized and investigated by a combination of X-ray crystallography, PXRD, electrochemistry, in-situ UV-Vis spectroelectrochemistry and DLS. Both of the two complexes feature a core composed of four Ni(II) ions with the same peripheral ligation provided by the anionic di(pyridin-2-yl)methanediol and MeCOO- ligands. Whereas, complex 1 possesses one distorted cubane-like [Ni4(µ3-O)4] core, while 2 has one extended butterfly-like [Ni4(µ3-O)2] core. The homogeneous electrocatalytic reactivity of the two water-soluble complexes for water oxidation have been thoroughly studied, which demonstrates that both of them can efficiently electrocatalyze water oxidation with high stability under alkaline conditions, at relatively low over-potentials (η) of 420-790 mV for 1 and 390-780 mV for 2, both in the pH range of 7.67-12.32, with the high TOF of about 139 s-1 (1) and 69 s-1 (2) at pH = 12.32, respectively. By a series of comparative experiments for complexes 1 and 2, we proposed that their crystal geometries play an important role in their electrocatalytic reactivity for water oxidation. We verified that biomimetic cubane geometry could promote OER catalysis with two very similar compounds for the first time. Compared with 2, the biomimetic cubane topology of 1 could promote OER catalysis by facilitating efficient charge delocalization and electron-transfer.
Assuntos
Complexos de Coordenação/química , Níquel/química , Água/química , Materiais Biomiméticos/química , Catálise , Eletroquímica , Concentração de Íons de Hidrogênio , Modelos Moleculares , Conformação Molecular , OxirreduçãoRESUMO
Hydrogen evolution reaction (HER) in alkaline medium is currently under scientific spotlight for generating clean H2 fuel from electrochemical water splitting. However, alkaline HER suffers from sluggish reaction kinetics because of the additional energy required for water dissociation from catalysts in contrast to acidic HER. Herein, we report the development of two-dimensional metal-organic framework (2D MOF) Ni-1,4-benzenedicarboxylic acid-based composite nanosheets for superior performance in HER electrocatalysis. Iron phthalocyanine (FePc) molecules are uniformly anchored on the ultrathin 2D Ni-MOF, showing a substantially increased current density, improved activity, and enhanced durability in alkaline HER. On account of the ultralarge specific surface of Ni-MOF and the coupling effects between FePc and 2D MOFs, the resultant nanosheet catalyst FePc@Ni-MOF exhibits a low overpotential (334 mV) and satisfactory long-term stability (10 h) at a current density of 10 mA·cm-2, which outperform those of pristine FePc, Ni-MOF, and the counterpart FePc@bulk-MOF. This study provides new insights into the synthesis of robust MOF-based nanosheet composites with high performance in catalysis.
RESUMO
The development and application of nano-biochar synthesized by ball milling technology is still challenging in the field of environmental remediation because of its higher activity with pollutants. The purpose of this study was to investigate the transport behavior of two kinds of biochar nanoparticles (nanobiochar (NBC) and nZVI-modified nanobiochar (nZVI-NBC)) and Cd2+ in clay mineral (kaolinite, illite, and montmorillonite)-coated quartz sand columns. The interaction between biochar nanoparticles and Cd2+ in saturated porous media was studied in cotransport experiments. Then, the effect of biochar nanoparticles on the release of Cd2+ in contaminated media was explored by elution experiments. The cotransport experiments showed that the mobility of Cd2+ was enhanced by two kinds of biochar nanoparticles, while the transport of biochar was limited due to the presence of Cd2+. The elution experiments showed that the transport of biochar nanoparticles can be inhibited by Cd2+ previously immobilized in the sand column, and Cd2+ can be rereleased by biochar nanoparticles. The rerelease ability of nZVI-NBC to Cd2+ is weaker than that of NBC because nZVI is more easily retained in the sand column after oxidation, thus strengthening the immobilization of Cd2+. In general, the recoveries of NBC, nZVI-NBC and Cd2+ in saturated porous media were reduced by the presence of clay minerals. The experimental results describing the stability of biochar nanoparticles in sand columns are consistent with those predicted by the Derjaguin-Landau-Verwey-Overbeek theory. The transport behavior of Cd2+ and biochar nanoparticles in sand columns can be well simulated by advection-dispersion-reaction. These findings reveal the interaction between biochar nanoparticles and heavy metals in the soil environment and provide new insights into the transport and fate of environmental remediation materials and pollutants in the underground environment.
RESUMO
Currently, there is tremendous interest in the discovery of new and improved photothermal agents for near-infrared (NIR)-driven cancer therapy. Herein, a series of novel photothermal agents, comprising copper nanoparticles supported on defective porous carbon polyhedra are successfully prepared by heating a Cu-BTC metal-organic framework (MOF) precursor at different temperatures (t) in the range 400-900 °C under an argon atmosphere. The copper nanoparticle size and carbon defect concentration in the obtained products (denoted herein as Cu@CPP-t) increase with synthesis temperature, thus imparting the Cu@CPP-t samples with distinct NIR absorption properties and photothermal heating responses. The Cu@CPP-800 sample shows a remarkable photothermal conversion efficiency of 48.5% under 808 nm laser irradiation, representing one of the highest photothermal efficiencies yet reported for a carbon-based photothermal agent. In vivo experiments conducted with tumor bearing nude Balb/c mice confirm the efficacy of Cu@CPP-800 as a very promising NIR-driven phototherapy agent for cancer treatment. Results encourage the wider use of MOFs as low cost precursors for the synthesis of carbon-supported metal nanoparticle composites for photothermal therapy.