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OBJECTIVES: We aimed to investigate the efficacy of B-vitamin and folic acid supplementation in slowing down cognitive function decline among older adults. METHODS: We searched databases for trials comparing B-vitamin and folate supplementation versus placebo in older adults identified with or without impaired cognition. RESULTS: 23 articles were eligible and included in this meta-analysis. The mean difference (MD) in homocysteine levels was significant between the compared groups (MD:-4.52; 95%CI:-5.41 to 3.63, P < 0.001). However, the difference in the Mini-Mental State Examination (MMSE) was non-significant between the compared groups with or without cognitive impairment (MD:0.19; 95%CI: -0.148 to 0.531, P = 0.27), and (MD:0.04; 95%CI:-0.1 to 0.18, P = 0.59), respectively. The difference in Clinical Dementia Rating-sum of box (CDR-SOB) scores was non-significant (MD:-0.16; 95%CI:-0.49 to 0.18; P = 0.36). CONCLUSIONS: B-vitamin and folate supplementations significantly reduced homocysteine levels. However, it failed to provide significant benefits over placebo in preventing or slowing the decline in cognitive function.
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Trastornos del Conocimiento , Demencia , Complejo Vitamínico B , Humanos , Anciano , Ácido Fólico/uso terapéutico , Vitamina B 12/uso terapéutico , Trastornos del Conocimiento/tratamiento farmacológico , Complejo Vitamínico B/uso terapéutico , Suplementos Dietéticos , Cognición , Homocisteína/uso terapéuticoRESUMEN
BACKGROUND: The clinical presentation of hospital-acquired pneumonia (HAP) in older patients is often complex and non-specific, posing a diagnostic challenge. This study evaluates the value of serum soluble triggering receptor expressed on myeloid cells-1 (sTREM-1) and heparin-binding protein (HBP) in combination with traditional inflammatory markers procalcitonin (PCT) and C-reactive protein (CRP) in diagnosing HAP in older patients. METHODS: Thirty-eight elderly male patients with HAP (≥ 80 years old) and 46 age-matched controls, who were hospitalized for other reasons than HAP, were enrolled. The serum sTREM-1, HBP, PCT and CRP levels were measured by ELISA on the first day after enrollment. In addition, routine blood test, blood gas, sputum analysis, clinical pulmonary infection score (CPIS) assessment, and chest X-ray were performed, and the correlations with HAP were analyzed. RESULTS: The serum sTREM-1 (n = 38, 170.75 ± 158.33 pg/ml), HBP (2.08 ± 0.50), PCT (9.44 ± 17.73) and CRP (79.63 ± 71.37) were all significantly higher in the HAP group, when compared to the control group (P < 0.05). Furthermore, the values were positively correlated with the CPIS. The ROC curve analysis revealed that the AUC for sTREM-1 (0.667) and HBP (0.711) were lower, when compared to that for PCT (AUC = 0.839) and CRP (AUC = 0.840). The combination of PCT and CRP with sTREM-1 (AUC = 0.927) or HBP (AUC = 0.930) had the highest AUC values. CONCLUSION: Serum sTREM-1, HBP, PCT and CRP can all be used as diagnostic markers for HAP in the elderly. The combination of traditional inflammatory markers PCT and CRP with novel inflammatory marker sTREM-1 or HBP further improves the diagnostic performance.
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Neumonía Asociada a la Atención Médica , Neumonía , Anciano de 80 o más Años , Péptidos Catiónicos Antimicrobianos , Biomarcadores , Proteínas Sanguíneas , Proteína C-Reactiva/análisis , Hospitales , Humanos , Masculino , Neumonía/diagnóstico , Polipéptido alfa Relacionado con Calcitonina , Estudios Prospectivos , Receptor Activador Expresado en Células Mieloides 1RESUMEN
Development of biosensing platforms plays a key role in research settings for identification of biomarkers and in clinical applications for diagnostics. Biosensors based on nucleic acids have taken many forms, from simple duplex-based constructs to stimuli-responsive nucleic acid nanostructures. In this review, we look at various nucleic acid-based biosensors, the different read-out strategies employed, and their use in chemical and biological sensing. We also look at current developments in DNA nanotechnology-based biosensors and how rational design of such constructs leads to more efficient biosensing platforms.
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Técnicas Biosensibles/métodos , Ácidos Nucleicos/química , Animales , Técnicas Biosensibles/instrumentación , ADN/química , Transferencia Resonante de Energía de Fluorescencia/métodos , Humanos , Modelos Moleculares , Conformación de Ácido NucleicoRESUMEN
Acute lung injury (ALI) is the leading cause of death in patients with sepsis syndrome and without effective protective or therapeutic treatments. Acacetin, a natural dietary flavonoid, reportedly exerts several biological effects, such as anti-tumor, anti-inflammatory, and anti-oxidative effects. However, acacetin's effect and underlying mechanism on sepsis-induced ALI remain unclear. Here, the mouse model was established to explore the impact of acacetin on sepsis-induced ALI. Acacetin significantly increased ALI murine survival and attenuated lung injury in histological examinations. Additionally, acacetin down-regulated myeloperoxidase activity, protein concentration, and number of neutrophils and macrophages in bronchoalveolar lavage fluid. Subsequently, inflammatory cytokines, including TNF-α, IL-1ß, and IL-6, were examined. Results showed that acacetin dramatically suppressed the production of TNF-α, IL-1ß, and IL-6. These above results indicated that acacetin attenuated sepsis-induced ALI by inhibiting the inflammatory response. Moreover, acacetin inhibited the expression of markers for M1-type (iNOS, CD86) macrophages and promoted the expression of markers for M2-type (CD206, Arg1) macrophages by western blot. In addition, acacetin down-regulated the expression TRAF6, NF-κB, and Cyclooxygenase-2 (COX2) by western blot. The high concentration of acacetin had a better effect than the low concentration. Besides, over-expression of TRAF6 up-regulated the expression of COX2, CD86, and iNOS, and the ratio of p-NF-κB to NF-κB increased the mRNA levels of TNF-α, IL-1ß, and IL-6, down-regulated the expression of CD206 and Arg1. The effects of TRAF6 were the opposite of acacetin. And TRAF6 could offset the impact of acacetin. This study demonstrated that acacetin could prevent sepsis-induced ALI by facilitating M2 macrophage polarization via TRAF6/NF-κB/COX2 axis.
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Lesión Pulmonar Aguda , Sepsis , Humanos , Ratones , Animales , FN-kappa B/metabolismo , Ciclooxigenasa 2/efectos adversos , Ciclooxigenasa 2/metabolismo , Factor 6 Asociado a Receptor de TNF/metabolismo , Factor de Necrosis Tumoral alfa/metabolismo , Interleucina-6/metabolismo , Transducción de Señal , Lesión Pulmonar Aguda/tratamiento farmacológico , Macrófagos/metabolismo , Antiinflamatorios/uso terapéutico , Sepsis/tratamiento farmacológico , Lipopolisacáridos/farmacologíaRESUMEN
Large micropore surface area, superior electrical conductivity and suitable pore size are simultaneously desired characteristics for high-performance capacitive carbons. However, these desired features tend to be mutually competing, and are generally difficult to integrate into a single carbon. Considering this challenge, we developed a sustainable, less time-demanding, pollution-free strategy to construct highly graphitized porous carbon (GPC) by one-step heat-treatment. This approach achieves the need of the abovementioned characteristics for capacitive carbons, wherein potassium ferrate works as both an activating agent and graphitization catalyst to achieve synchronous hierarchical porosity and graphitization of wasted natural wood, and the resultant carbon materials possess a large micropore surface area of 870.4 m2 g-1, a highly graphitic carbon skeleton and a well-interconnected micro-meso-macropore structure. The assembled GPC-based symmetrical capacitors exhibited a satisfactory capacitive performance in different aqueous electrolytes (H2SO4, KOH and Na2SO4), including high specific capacitance, prominent rate capability, satisfactory energy density and good cycle stability. Meanwhile, we compared the contributions of porosity and the graphitized structure to capacitive performance, and porosity was dominant in determining capacitance and the graphitized skeleton had a positive effect in enhancing the capacitive performance. In addition, we established the relationship between the structure of GPC and electrochemical capacitive performance in different aqueous electrolytes, providing a valuable reference for GPC-based supercapacitors in different practical applications. More importantly, this strategy holds great promise to sustainably convert biowaste to high-added-value capacitive carbons for advanced energy storage applications in the future.
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To resolve problems caused by the accumulation of flue gas desulfurization gypsum (FGDG) in the environment, a polymer material was prepared using FGDG, granulated blast furnace slag (GBFS), fly ash (FA), and solid sodium silicate (SSS). The compressive strength of these polymer specimens cured for 3, 28, and 60 d was regularly measured, and their condensation behavior was analyzed. Both the formation behavior of mineral crystals and microstructure characteristics were analyzed further using X-ray diffraction and scanning electron microscopy. The compressive strength of pure FGDG polymer specimen (whose strength is generated by particle condensation crystallization) is insufficient and the condensation is slow. The addition of appropriate amounts of GBFS, FA, and SSS can continuously and considerably improve the compressive strength and shorten the setting time. The optimal proportions of FGDG, GBFS, and FA are 50%, 20%, and 30%, respectively, with the SSS addition amount of 20 g. The incorporation of GBFS, FA, and SSS can promote the polymerization of calcium, silicon, and aluminum in FGDG to form silicate and aluminosilicate minerals. Their formation is the main reason for the increased compressive strength and accelerated coagulation.
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In deep coal mining, grouting reinforcement and water blockage are the most effective means for reinforcing the rock mass of extremely broken coal. However, traditional cement grouting materials are not suitable for use in complex strata because of their insufficient early mechanical strength and slow setting time. This study innovatively proposes using alkali-activated grouting material to compensate for the shortcomings of traditional grouting materials and strengthen the reinforcement of extremely unstable broken coal and rock mass. The alkali-activated grouting material was prepared using slag as raw material combined with sodium hydroxide and liquid sodium silicate activation. The compressive strength of specimens cured for 1 d, 3 d, and 28 d was regularly measured and the condensation behavior was analyzed. Using X-ray diffraction and scanning electron microscopy, formation behavior of mineral crystals and microstructure characteristics were further analyzed. The results showed that alkali-activated slag grouting material features prompt and high strength and offers the advantages of rapid setting and adjustable setting time. With an increase in sodium hydroxide content, the compressive strength first increased (maximum increase was 21.1%) and then decreased, while the setting time continued to shorten. With an increase in liquid sodium silicate level, the compressive strength increased significantly (and remained unchanged, maximum increase was 35.9%), while the setting time decreased significantly (and remained unchanged). X-ray diffraction analysis identified the formation of aluminosilicate minerals as the main reason for the excellent mechanical properties and accelerated coagulation rate.
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Designing plasmonic photocatalysts with spatially controlled catalytic sites is an effective strategy to boost the sunlight-driven chemical transformation efficiency through plasmonic enhancement. Herein, we describe a facile method for the synthesis of TiO2-tipped Au nanobipyramids (NBPs) to give (Au NBP)/t-TiO2 nanodumbbells. The surfactant cetyltrimethylammonium bromide concentration is the key factor in the construction of this type of unique nanostructure. The photocatalytic aerobic oxidative coupling of amines using the plasmonic photocatalysts with the dumbbell-like and core@shell structures indicates that the TiO2-tipped ends for the photo-reduction and the exposed adjacent Au surface for the photo-oxidation on (Au NBP)/t-TiO2 can significantly improve the photocatalytic activity. The underlying mechanism of the photocatalytic oxidative coupling of benzylamine over (Au NBP)/t-TiO2 has been thoroughly investigated. Both experimental and simulation results for (Au NBP)/t-TiO2 and (Au nanorod)/t-TiO2 confirm the important effect of the plasmonic hotspots on the enhancement of the photocatalytic activity.
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OBJECTIVE: To investigate the roles of DNA double stains damage repairing mechanisms in high glucose-induced cellular senescence. METHODS: Human umbilical vein endothelial cells (HUVECs) were incubated with different concentrations of glucose (5.5 mmol/L, 11 mmol/L, 22 mmol/L and 33 mmol/L) for 72 hrs before the assay of senescence-associated beta-galactosidase staining. The superoxides were detected by flow cytometry. The levels of NO were detected by enzyme assay. Gamma-H2AX and phosphorylated P53 protein were measured by Western blot. Changes after co-incubation with KU55993 (an inhibitor of ATM) were examined with methods mentioned above. RESULTS: Compared with control group, percentage of positive cells of senescence-associated beta-galactosidase staining increased significantly in high glucose groups. The corresponding levels of reactive oxygen increased and NO decreased in a concentration-dependent manner. Intra-cellular levels of gamma-H2AX and phosphorylated P53 protein were significantly increased in high glucose groups. Statistical significances were revealed between high-glucose group and control group, as well as among different high-glucose groups, but no significant difference was observed between mannitol and control group. KU55993, an inhibitor of ATM, significantly reduced the levels of gamma-H2AX, phosphorylated P53 protein, and positive rate of senescence-associated beta-galactosidase staining. CONCLUSION: High glucose may promote DNA double strains damage by enhancing oxidative stress and decreasing NO, and thus accelerate cellular senescence. ATM-P53 pathway, the key proteins related to DNA double strain damage repairing mechanisms, may play an important role in high glucose induced cellular senescence and atherosclerosis.
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Senescencia Celular/efectos de los fármacos , Daño del ADN/efectos de los fármacos , Glucosa/farmacología , Células Endoteliales de la Vena Umbilical Humana/patología , Células Cultivadas , Roturas del ADN de Doble Cadena/efectos de los fármacos , Histonas/metabolismo , Células Endoteliales de la Vena Umbilical Humana/metabolismo , Humanos , Morfolinas , Óxido Nítrico/análisis , Pironas , Proteína p53 Supresora de Tumor/metabolismo , beta-Galactosidasa/metabolismoRESUMEN
OBJECTIVE: To investigate the relationship between blood pressure variability (BPV)and target-organ damage in elderly patients with hypertension. METHODS: A total of 197 elderly patients were included in the study. The participants were divided into two groups: those with hypertension (n=146) and those without hypertension (Control, n=51). The 24 h systolic and diastolic blood pressure variability (24 h SBPV/DBPV),24 h average systolic and diastolic blood pressure (24 h SBP/DBP), day time systolic and diastolic blood pressure variability (d SBPV/DBPV),and night time systolic and diastolic blood pressure variability (n SBPV/DBPV)were measured. The hypertensive group was further divided into low and high variability groups according to the 50th percentile of 24 h SBPV. The carotid artery intima-media thickness (IMT), left ventricular mass index (LVMI), 24 h microalbuminuria (MA) and basic clinical and laboratory parameters were compared among the groups. The correlations between blood pressure variability and IMT, LVMI, and MA were analyzed with multivariable regression analyses. RESULTS: The patients with essential hypertension had significantly higher 24 h SBPV (P < 0.001) and d SBPV (P < 0.05) than those without hypertension. The patients with higher blood pressure variability had greater incidence of plaque and cardiovascular disorder, as well as IMT, LVMI and MA (P < 0.001). The prevalence of diabetes mellitus (DM) differed significantly among the three groups of participants (P < 0.05). The multivariable regression analysis showed that 24 h SBPV was independently correlated with IMT, LVMI and MA. CONCLUSION: Elderly patients with hypertension have high BPV, which is an important independent predictor of target-organ damage.
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Monitoreo Ambulatorio de la Presión Arterial , Enfermedad Coronaria/etiología , Hipertensión/complicaciones , Hipertensión/fisiopatología , Riñón/fisiopatología , Anciano , Anciano de 80 o más Años , Aterosclerosis/etiología , Aterosclerosis/fisiopatología , Arterias Carótidas/patología , Estudios de Casos y Controles , Enfermedad Coronaria/fisiopatología , Femenino , Humanos , Pruebas de Función Renal , Masculino , Persona de Mediana EdadRESUMEN
The superior ultramicroporosity and enriched surface CO2-philic sites are simultaneously required features for high-efficiency carbon-based CO2 adsorbents. Unfortunately, these characteristics are usually incompatible and difficult to integrate into one porous carbon material. Herein, we report a new copper ions (Cu2+)-assisted dynamic porogen to construct hierarchically microporous carbon nanosheets in a large scale with high heterogeneity for solving such issue. Cu2+ can be equably dispersed in precursor by coordination interactions of COO-Cu and Cu-N, which can anchor more N/O-containing species in final product. The reduced cuprous ions (Cu+) in pyrolysis process functions as a dynamic porogen to tailor uniform ultramicropores. Importantly, copper salt extracted in this synthetic procedure allows cyclic utilization, realizing a green and low-cost process. The obtained carbon sheets possess a graphene-like morphology, a high surface area and a high-proportioned multiscale microporosity, especially a high-density ultramicropores of 0.4-0.7 nm and supermicroproes of 0.8-1.5 nm. The maximized synergistic effect of morphology, high density of multi-sized ultramicroporosity and surface high heterogeneity endow the resultant microporous carbon nanosheets with the remarkable CO2 capture property, including a high uptake, a moderate adsorption heat, a good selectivity and superior recyclability.
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Benefiting from the superior conductivity, rich surface chemistry and tunable bandgap, Ti3C2 MXene has become a frontier cocatalyst material for boosting the efficiency of semiconductor photocatalysts. It has been theoretically predicted to be an ideal material for N2 fixation. However, the realization of N2 photofixation with Ti3C2 as a host photocatalyst has so far remained experimentally challenging. Herein, we report on a sandwich-like plasmon- and an MXene-based photocatalyst made of Au nanospheres and layered Ti3C2, and demonstrate its efficient N2 photofixation in pure water under ambient conditions. The abundant low-valence Ti (Ti(4-x)+) sites in partially reduced Ti3C2 (r-Ti3C2) produced by surface engineering through H2 thermal reduction effectively capture and activate N2, while Au nanospheres offer plasmonic hot electrons to reduce the activated N2 into NH3. The Ti(4-x)+ active sites and plasmon-generated hot electrons work in tandem to endow r-Ti3C2/Au with remarkably enhanced N2 photofixation activity. Importantly, r-Ti3C2/Au exhibits ultrahigh selectivity without the occurrence of competing H2 evolution. This work opens up a promising route for the rational design of efficient MXene-based photocatalysts.
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Heterojunction construction has been proved to be an effective way to enhance photocatalysis performance. In this work, Cl-doped carbon nitride nanofibers (Cl-CNF) with broadband light harvesting capacity were in situ grown on carbon nitride nanosheets (CNS) by a facile hydrothermal method to construct a type II heterojunction. Benefiting from the joint effect of the improved charge carriers separation efficiency and a broadened visible light absorption range, the optimal heterostructure of Cl-CNF/CNS exhibits a H2O2 evolution rate of 247.5 µmol g-1 h-1 under visible light irradiation, which is 3.4 and 3.1 times as much as those of Cl-CNF (72.2 µmol g-1 h-1) and CNS (80.2 µmol g-1 h-1), respectively. Particularly, the heterojunction nanostructure displays an apparent quantum efficiency of 23.67% at 420 nm. Photoluminescence spectra and photocurrent measurements both verified the enhanced charge carriers separation ability. Our work provides a green and environmentally friendly strategy for H2O2 production by elaborate nanostructure design.
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BACKGROUND: Currently, China is carrying forward "Healthy China" construction. Thus, health investment has gradually become an important issue concerned by the Chinese government. Exploring the influence of health investment on economic growth under this background is of great theoretical and realistic significance for realizing economic transformation and upgrading in China. METHODS: Thirty-one provincial regions in China were selected as research objects. Based on the panel data during 2000-2017, difference-generalized method of moment (D-GMM) and system-generalized method of moment (S-GMM) were comprehensively used to estimate the dynamic panel model from the national perspective, combining the fixed effects model (FE) estimation method to estimate the static panel model from the regional perspective, so as to investigate the relationships among governmental, residential health investment, and economic growth. RESULTS: First, the governmental and residential health investments have positive effects on economic growth. Second, from the perspective of different regions, the governmental and residential health investments present positive correlations with economic growth, but the correlations present a progressively decreasing trend from the east to west. CONCLUSION: The Chinese government needs to steadily increase governmental health investment, elevate the level of residents' health expenditure, promote the development of the health industry, and finally facilitate sustainable economic growth in China.
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Light-harvesting capacity and photoexcited charge carrier separation ability are two crucial requirements for high-efficiency semiconductor photocatalysis. Here, we report a plasmonic Z-scheme nanohybrid by hydrothermally in-situ growing two-dimensional (2D) oxygen-deficient molybdenum oxide (MoO3-x) nanoplates onto 2D graphitic carbon nitride (g-C3N4) nanosheets. The resultant 2D/2D MoO3-x/g-C3N4 nanohybrids not only construct a unique Z-scheme heterojunction, which improves the photogenerated charge carrier separation efficiency, but also possess numerous oxygen vacancies on the surface of MoO3-x, which could excite its plasmon resonance for extending spectrum adsorption. Importantly, the plasmon resonance can be readily designed by tailoring the oxygen vacancy concentration via an annealing in air. Benefiting from the synergetic effect of interfacial Z-scheme heterojunction and the tunable plasmon resonance of MoO3-x, the as-obtained nanohybrids achieve a remarkably improved photocatalytic H2 evolution efficiency. The optimal Z-scheme heterostructure presents 2.6 and 1.7 times higher of H2 evolution rate as compared to pure g-C3N4 and the annealing nanohybrid under visible light irradiation. Even under light irradiation with wavelength longer than 590 nm, the hybrid photocatalyst displays a H2 generation rate as high as 22.8 µmol h-1 due to the plasmonic sensitization effect. The result in our work can provide an alternative for fabricating Z-scheme heterostructures that take advantages of Z-scheme-induced charge carrier separation, accompanied with plasmon-enhanced light harvesting of semiconductor to advance the solar energy conversion efficiency in photocatalysis.
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OBJECTIVE: To study the effects of total flavonoids of Hippophae rhamnoides L. (TFH) on the expression of monocyte chemoattractant protein (MCP-1) in aorta of Spontaneously Hypertensive Rats (SHR) and to study the relationship of expression of MCP-1 in aorta and intimal medial thickness (IMT) of aorta. METHODS: Twelve-week-old male SHR (n=12) were randomly devided into three groups to receive TFH [30 mg/(kg x d), n=4], Enalapril [10 mg/(kg x d), n= 4] and Hydrochlorothiazide [25 mg/(kg x d), n=4] for 12 weeks, respectively. Another 4 SHR and 4 WKY which receive placebo served as positive control group and negative control group. The systolic blood pressure (SBP), intimal medial thickness and inside diameter of aorta of the rats were measured. The expression of MCP-1 in aorta was examined by real-time PCR and immunohistochemistry and the concentration of serum MCP-1 protein by ELSA. RESULTS: Twelve weeks later, systolic blood pressure in TFH was significantly decreased, compared with that in Enalapril and Hydrochlorothiazide without statistical differences. TFH markedly reduced the intimal medial thickness of aorta and expression of MCP-1 in aorta, similar with Enalapril, stronger than Hydrochlorothiazide. CONCLUSION: TFH can markedly decrease SBP of SHR and the decrease value of the TFH group was similar with that of the Enalapril and Hydrochlorothiazide group. TFH may inhibit the expression of MCP-1 in aorta and intimal medial thickness of aorta beyond BP Lowering effect. The effect of THF on the expression of MCP-1 and intimal medial thickness of aorta was similar with Enalapril. TFH may through inhibite the expression of MCP-1 in aorta to reduce the intimal medial thickness of aorta and protect hypertensive injury in target organs.
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Antihipertensivos/uso terapéutico , Quimiocina CCL2/metabolismo , Flavonoides/uso terapéutico , Hippophae/química , Hipertensión/tratamiento farmacológico , Animales , Aorta Torácica/metabolismo , Aorta Torácica/patología , Quimiocina CCL2/genética , Hipertensión/metabolismo , Hipertensión/patología , Masculino , ARN Mensajero/genética , ARN Mensajero/metabolismo , Distribución Aleatoria , Ratas , Ratas Endogámicas SHR , Ratas Endogámicas WKYRESUMEN
Considering the characteristics of abundant narrow micropores of <1 nm, appropriate proportion of mesopores/macropores and suitable surface functionalization for a highly-efficient carbon-based CO2 adsorbent, we proposed a facile and cost-effective strategy to prepare N and S dual-doped carbons with well-interconnected hierarchical pores. Benefiting from the unique structural features, the resultant optimal material showed a prominent CO2 uptake of up to 7.76 and 5.19 mmol g-1 at 273 and 298 K under 1 bar, and importantly, a superb CO2 uptake of 1.51 mmol g-1 at 298 K and 0.15 bar was achieved, which was greatly significant for CO2 capture from the post-combustion flue gases in practical application. A systematic study demonstrated that the synergetic effect of ultramicroporosity and surface functionalization determined the CO2 capture properties of porous carbons, and the synergistic influence mechanism of nitrogen/sulfur dual-doping on CO2 capture performance was also investigated in detail. Importantly, such as-prepared carbon-based CO2 adsorbents also showed an outstanding recyclability and CO2/N2 selectivity. In view of cost-effective fabrication, the excellent adsorption capacity, high selectivity and simple regeneration, our developed strategy was valid and convenient to design a novel and highly-efficient carbonaceous adsorbent for large-scale CO2 capture and separation from post-combustion flue gases.
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Cross-linked microporous carbon beads (MCBs) were successfully synthesized via a green, convenient, and cost-efficient strategy derived from a renewable sugar source. Such an approach avoids the time-consuming procedure and the use of corrosive chemical activating agents and toxic solvents and only involves a simple carbonization process, which makes it to be applicable for rapid and large-scale industrial production of MCB materials. The obtained MCBs possessed well-defined microporous structure, narrow pore size, and high surface area. Particularly, the microporosity of the resultant MCBs could be easily tailored to arise primary pores of size 0.5-0.9 nm by adjusting the carbonization temperature and reaction time, which remarkably favor the CO2 capture. The optimal sample of MCBs-9-5 carbonized at 900 °C for 5 h was characterized by high microporosity (80% of the surface area from micropores), especially ultrahigh narrow microporosity (53% of pore volume from micropores of size <1 nm), which endowed it a great satisfactory CO2 uptake of 4.25 mmol g-1 at 25 °C and 1 bar. Significantly, a prominent CO2/N2 selectivity and superior recyclability of MCBs-9-5 were also achieved. Combined with the simple fabrication, the satisfactory adsorption capacity, and high selectivity, MCBs-9-5 should be a promising adsorbent for CO2 capture and separation.
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Hydrogen production by catalytic water splitting using sunlight holds great promise for clean and sustainable energy source. Despite the efforts made in the past decades, challenges still exist in pursuing solid catalysts with light-harvesting capacity, large surface areas and efficient utilities of the photogenerated carrier, at the same time. Here, a multiple structure design strategy leading to highly enhanced photocatalytic performance on hydrogen production from water splitting in Dion-Jacobson perovskites KCa2 Nan-3 Nbn O3n+1 is described. Specifically, chemical doping (N/Nb4+ ) of the parent oxides via ammoniation improved the ability of sunlight harvesting efficiently; subsequent liquid exfoliation of the doped perovskites yielded ultrathin [Ca2 Nan-3 Nbn O3n+1 ]- nanosheets with greatly increased surface areas. Significantly, the maximum hydrogen evolution appears in the n=4 nanosheets, which suggests the most favorable thickness for charge separation in such perovskite-type catalysts. The optimized black N/Nb4+ -[Ca2 NaNb4 O13 ]- nanosheets show greatly enhanced photocatalytic performance, as high as 973â µmol h-1 with Pt loading, on hydrogen evolution from water splitting. As a proof-of-concept, this work highlights the feasibility of combining various chemical strategies towards better catalysts and precise thickness control of two-dimensional materials.
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Heterostructures consisting of two semiconductors have merited considerable attention in photocatalytic applications due to synergistic effects in complex redox processes. The incorporation of solid solutions into such architectures can further offer extra variability to control the bandgap. In this study, we report the fabrication of a series of core-shell Cd0.2Zn0.8S@BiOX (X = Cl, Br and I) microspheres via a solvothermal route that lead to enhanced photocatalytic performance under visible light irradiation. By optimizing the synthesis conditions, uniform and porous Cd0.2Zn0.8S@BiOX microspheres were achieved. The products were thoroughly characterized by X-ray diffraction studies, scanning electron microscopy, transmission electron microscopy, photoluminescence studies, absorption measurements and the photodegradation of RhB. Remarkably, the electronic structures of Cd0.2Zn0.8S@BiOX composites can be continuously tuned by varying the composition of BiOX to achieve the best catalytic performance under visible light irradiation. Finally, this greatly enhanced visible-light-driven photocatalytic efficiency was observed in the optimized Cd0.2Zn0.8S@BiOI composites when compared to their single-component counterparts, which may be attributed to increased light absorption and improved electron-hole separation. The photocatalytic mechanism has also been proposed based on the experimental evidences and the theoretical band positions of Cd0.2Zn0.8S@BiOI.