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1.
Int J Health Geogr ; 20(1): 24, 2021 05 28.
Artículo en Inglés | MEDLINE | ID: mdl-34049563

RESUMEN

BACKGROUND: Studies on the association between surrounding greenspace and being overweight in childhood show inconsistent results, possibly because they differ widely in their definition and measurement of surrounding greenspace. Our aim was to evaluate whether the association of greenspace with being overweight depends on the measurement of greenspace in different data sources. METHODS: Based on data from the school entry examinations of 22,678 children in the city of Hannover, Germany, from 2010 to 14, the association between greenspace availability and overweight was examined. Three different sources of greenspace availability were derived for a set of 51 areas of the city: The Normalized Difference Vegetation Index (NDVI), the OpenStreetMap (OSM) dataset, and the European Urban Atlas (UA) dataset. Agreement between the indicators on the quantity of greenspace coverage was compared. The association with children's BMI z-score, including potential interaction terms, was assessed using multilevel regression analysis. RESULTS: Greenspace availability per district area derived by NDVI was on average 42%, by OSM 29% and UA 22%, with OSM and UA being strongly correlated. Only the greenspace availability derived by NDVI showed an association with children's BMI z-score: The higher the greenspace availability was, the lower the BMI. The trend of association was higher for boys and migrant children than for girls and non-migrants and was restricted to the highest levels of greenspace availability. CONCLUSIONS: Associations of greenspace with children's weight status depend on the greenspace measurement chosen. Surrounding greenspace was measured more comprehensively by NDVI. Data sources based on land use categories such as UA and OSM may be less suitable to reflect surrounding greenspace relevant for health outcomes. Potential mechanisms warrant further analysis and investigation.


Asunto(s)
Sobrepeso , Parques Recreativos , Niño , Ciudades , Femenino , Alemania/epidemiología , Humanos , Almacenamiento y Recuperación de la Información , Masculino , Sobrepeso/diagnóstico , Sobrepeso/epidemiología
2.
J Phys Chem A ; 124(24): 5033-5041, 2020 Jun 18.
Artículo en Inglés | MEDLINE | ID: mdl-32436382

RESUMEN

To provide feasible methods for the extraction of valuable metals from spent batteries or low-grade primary ores, the extraction behavior of some representative acidic phosphorus-containing compounds (APCCs) as extractants is evaluated from the perspective of experimental and theoretical investigations in this work. Aqueous solutions containing five metal ions, Ca(II), Co(II), Mg(II), Mn(II), and Ni(II), were made to simulate leaching liquids, and the extraction of these metals was investigated. A simplified calculated model was used to evaluate the interaction between each extractant and metal ions. The calculation results agree well with the experimental tests in trend. This work not only provides potential extractants for the extraction of valuable metals from spent batteries or low-grade primary ores but also demonstrates the practicability of the simplified calculation model.

3.
Mar Policy ; 122: 104265, 2020 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-33106727

RESUMEN

Blockchain has the potential to improve the efficiency and transparency of maritime businesses and operations. Nevertheless, few studies have been conducted to identify the key challenges and critical success factors (CSFs) of blockchain implementation in the maritime industry. A case study approach based on Singapore's maritime industry is adopted. Four interviews are conducted to establish the face validity of the survey questionnaire before data are collected from 30 maritime professionals from Singapore's maritime industry. In addition to analytic hierarchical process (AHP), a fishbone diagram and PESTEL analysis are also adopted to organize and discuss the results. The results show that there are six key challenges and six CSFs for blockchain implementation. Using a fishbone diagram, the six identified challenges along with 13 personal concerns are categorized into five dimensions related to people, methods, organization, external environment, and technology. The CSFs are sufficient capital, staff training, ease of local legislation, support from the shipping community, support from the senior management, and professional consultation and assistance. This study implicates marine policy formulation in relation to subsidies and investments, blockchain talent and knowledge acquisition, and workforce training and education to accelerate blockchain implementation in the maritime industry.

4.
Sensors (Basel) ; 19(23)2019 Nov 25.
Artículo en Inglés | MEDLINE | ID: mdl-31775312

RESUMEN

The in situ scattering and transmissometry laser (LISST-100X), equipped with an acoustic wave and current (AWAC) meter and conductivity, temperature, and depth (CTD) instruments over the seabed in the East China Sea, was used to monitor the variation in suspended particles in the bottom sea layer, including particle size distribution (PSD) and volume concentration. The power law approximation was tested to describe the variability in PSD based on the field data. The results show that the power law was robust in processing continuous data, accompanied with the same optimal reference particle size (~63 µm) and little change in the corresponding exponent (~3.4) in both periods. Suspended particles were divided into three types: macroflocs (>133 µm), microflocs (36-133 µm), and single grains (<36 µm). Particle sizes were coarse during the two seasons, with macroflocs representing more than 60% of all the suspended particles, especially in February, when the particle size spectra were usually open-ended. Results from the harmonic analysis method indicate that tidal-induced resuspension and advection are the major reasons for the diurnal dynamics of sediments. Due to the tidal asymmetry in the region, we only found one mode in volume concentration at the moment of maximum velocity. However, the ratios of macroflocs were bimodal, with maximum floods and ebbs in one tidal cycle in February, when the higher mode at the maximum ebbs may be contributed to by the flocculation of finer particles considering the decreasing ratios of finer particles. Due to the enhanced stratification and the clean barrier built up by the Taiwan Warm Current in the southeast corner, the significant daily variation in suspended particles observed in February weakened in September. The influence of waves was uncertain, although the correlation coefficient between significant wave height and volume concentration was about 64% in February.

5.
Angew Chem Int Ed Engl ; 58(35): 12102-12106, 2019 08 26.
Artículo en Inglés | MEDLINE | ID: mdl-31233271

RESUMEN

An unconventional organic molecule (TBBU) showing obvious long-lived room temperature phosphorescence (RTP) is reported. X-ray single crystal analysis demonstrates that TBBU molecules are packed in a unique fashion with side-by-side arranged intermolecular aromatic rings, which is entirely different from the RTP molecules reported to date. Theoretical calculations verify that the extraordinary intermolecular interaction between neighboring molecules plays an important role in RTP of TBBU crystals. More importantly, the polymer film doped with TBBU inherits its distinctive RTP property, which is highly sensitive to oxygen. The color of the doped film changes and its RTP lifetime drops abruptly through a dynamic collisional quenching mechanism with increasing oxygen fraction, enabling visual and quantitative detection of oxygen. Through analyzing the grayscale of the phosphorescence images, a facile method is developed for rapid, visual, and quantitative detection of oxygen in the air.

6.
Eur J Pediatr ; 177(5): 753-763, 2018 May.
Artículo en Inglés | MEDLINE | ID: mdl-29470636

RESUMEN

Overweight and obesity constitute a global epidemic with rates that are increasing rapidly in children. The aim of the present study was to examine ethnic differences in the prevalence of overweight in pre-school children in a multicultural context. Data were collected from a compulsory school entry examination in the Hannover Region, Germany (n = 50,716) from 2010 to 2014. The prevalence of overweight (including pre-obesity and obesity status) and obesity was estimated using a German national reference. The migration status of the children was based on the parent's migration history. Multivariable logistic and hierarchical multinomial regression analyses were performed to identify factors associated with the overweight, pre-obesity, and obesity status. The prevalence of overweight was significantly higher among migrant children (12.7%) than among the non-migrant children (6.9%). After adjusting for socioeconomic and child development variables, migration background was strongly associated with weight status. The Turkish migrant children showed the highest odds of being pre-obesity (OR 2.05, 95%CI 1.7-2.56) and obesity (OR 2.09, 95%CI 1.67-2.77) compared to non-migrant children. CONCLUSION: Ethnic and social inequalities exist in childhood overweight among pre-school children in the Hannover Region. Thus, appropriate interventions targeting high-risk migrant groups are needed. What is Known: • The current trend of prevalence rates in Germany for overweight and obesity of pre-school children is becoming stable. • Prevalence of overweight and obesity is clearly higher among migrant children than among non-migrant children. What is New: • This article reveals ethnic variance among different migrant groups. • Turkish migrant children have a higher rate of prevalence even compared to other migrant groups. • Length of child day care attendance fails to exert a strong influence on overweight after adjusting for socio-economic and child development variables.


Asunto(s)
Obesidad Infantil/etnología , Migrantes/estadística & datos numéricos , Antropometría , Preescolar , Etnicidad , Femenino , Alemania/epidemiología , Humanos , Masculino , Prevalencia , Factores de Riesgo , Instituciones Académicas , Factores Socioeconómicos
7.
Sensors (Basel) ; 18(8)2018 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-30103440

RESUMEN

With the construction and deployment of seafloor observatories around the world, massive amounts of oceanographic measurement data were gathered and transmitted to data centers. The increase in the amount of observed data not only provides support for marine scientific research but also raises the requirements for data quality control, as scientists must ensure that their research outcomes come from high-quality data. In this paper, we first analyzed and defined data quality problems occurring in the East China Sea Seafloor Observatory System (ECSSOS). We then proposed a method to detect and repair the data quality problems of seafloor observatories. Incorporating data statistics and expert knowledge from domain specialists, the proposed method consists of three parts: a general pretest to preprocess data and provide a router for further processing, data outlier detection methods to label suspect data points, and a data interpolation method to fill up missing and suspect data. The autoregressive integrated moving average (ARIMA) model was improved and applied to seafloor observatory data quality control by using a sliding window and cleaning the input modeling data. Furthermore, a quality control flag system was also proposed and applied to describe data quality control results and processing procedure information. The real observed data in ECSSOS were used to implement and test the proposed method. The results demonstrated that the proposed method performed effectively at detecting and repairing data quality problems for seafloor observatory data.

8.
Cutan Ocul Toxicol ; 37(3): 233-239, 2018 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-29298533

RESUMEN

Lysergic acid diethylamide (LSD), a classical hallucinogen, was used as a popular and notorious substance of abuse in various parts of the world. Its abuse could result in long-lasting abnormalities in retina and little is known about the exact mechanism. This study was to investigate the effect of LSD on macrophage activation state at non-toxic concentration and its resultant toxicity to photoreceptor cells. Results showed that cytotoxicity was caused by LSD on 661 W cells after co-culturing with RAW264.7 cells. Treatment with LSD-induced RAW264.7 cells to the M1 phenotype, releasing more pro-inflammatory cytokines, and increasing the M1-related gene expression. Moreover, after co-culturing with RAW264.7 cells, significant oxidative stress in 661 W cells treated with LSD was observed, by increasing the level of malondialdehyde (MDA) and reactive oxygen species (ROS), and decreasing the level of glutathione (GSH) and the activity of superoxide dismutase (SOD). Our study demonstrated that LSD caused photoreceptor cell damage by inducing inflammatory response and resultant oxidative stress, providing the scientific rationale for the toxicity of LSD to retina.


Asunto(s)
Alucinógenos/toxicidad , Dietilamida del Ácido Lisérgico/toxicidad , Macrófagos/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacos , Células Fotorreceptoras de Vertebrados/efectos de los fármacos , Animales , Técnicas de Cocultivo , Citocinas/metabolismo , Macrófagos/inmunología , Ratones , Células Fotorreceptoras de Vertebrados/metabolismo , Células RAW 264.7
9.
Nano Lett ; 13(6): 2647-53, 2013 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-23635319

RESUMEN

Investigating the piezotronic effect in p-type piezoelectric semiconductor is critical for developing a complete piezotronic theory and designing/fabricating novel piezotronic applications with more complex functionality. Using a low temperature solution method, we were able to produce ultralong (up to 60 µm in length) Sb doped p-type ZnO nanowires on both rigid and flexible substrates. For the p-type nanowire field effect transistor, the on/off ratio, threshold voltage, mobility, and carrier concentration of 0.2% Sb-doped sample are found to be 10(5), 2.1 V, 0.82 cm(2)·V(-1)·s(-1), and 2.6 × 10(17) cm(-3), respectively, and the corresponding values for 1% Sb doped samples are 10(4), 2.0 V, 1.24 cm(2)·V(-1)·s(-1), and 3.8 × 10(17) cm(-3). We further investigated the universality of piezotronic effect in the as-synthesized Sb-doped p-type ZnO NWs and reported for the first time strain-gated piezotronic transistors as well as piezopotential-driven mechanical energy harvesting based on solution-grown p-type ZnO NWs. The results presented here broaden the scope of piezotronics and extend the framework for its potential applications in electronics, optoelectronics, smart MEMS/NEMS, and human-machine interfacing.


Asunto(s)
Nanoestructuras , Nanocables , Óxido de Zinc/química , Sistemas Hombre-Máquina , Microscopía Electrónica de Rastreo
10.
Nano Lett ; 13(2): 847-53, 2013 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-23360548

RESUMEN

This article describes a simple, cost-effective, and scalable approach to fabricate a triboelectric nanogenerator (NG) with ultrahigh electric output. Triggered by commonly available ambient mechanical energy such as human footfalls, a NG with size smaller than a human palm can generate maximum short-circuit current of 2 mA, delivering instantaneous power output of 1.2 W to external load. The power output corresponds to an area power density of 313 W/m(2) and a volume power density of 54,268 W/m(3) at an open-circuit voltage of ~1200 V. An energy conversion efficiency of 14.9% has been achieved. The power was capable of instantaneously lighting up as many as 600 multicolor commercial LED bulbs. The record high power output for the NG is attributed to optimized structure, proper materials selection and nanoscale surface modification. This work demonstrated the practicability of using NG to harvest large-scale mechanical energy, such as footsteps, rolling wheels, wind power, and ocean waves.

11.
Can J Cardiol ; 40(6): 1102-1109, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38428522

RESUMEN

Atrial fibrillation (AF), the most prevalent cardiac arrhythmia, poses a significant public health and economic burden. Although socioeconomic factors such as income and education have been implicated in AF incidence and outcomes, the potential sex-specific associations remained underexplored. This narrative review aimed to fill this gap by synthesizing existing literature on the sex-specific impact of socioeconomic factors on AF incidence, treatment, and outcome. Among these socioeconomic factors, we identified income and education as the most frequently cited determinants. Nevertheless, the magnitude and direction of these sex differences remained inconsistent across studies. The review uncovered that many studies did not include sex in the analysis when assessing the impact of socioeconomic factors on AF. We highlighted that there is a paucity of studies employing sex-stratified reporting and sex interaction analyses, thereby hindering a deeper understanding of these relationships.


Asunto(s)
Fibrilación Atrial , Factores Socioeconómicos , Humanos , Fibrilación Atrial/epidemiología , Fibrilación Atrial/terapia , Fibrilación Atrial/economía , Factores Sexuales , Incidencia , Femenino , Factores de Riesgo , Masculino , Salud Global
12.
Adv Mater ; 36(16): e2312439, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38281100

RESUMEN

Afterglow materials featuring long emission durations ranging from milliseconds to hours have garnered increasing interest owing to their potential applications in sensing, bioimaging, and anti-counterfeiting. Unfortunately, polymeric materials rarely exhibit afterglow properties under ambient conditions because of the rapid nonradiative decay rate of triplet excitons. In this study, hour-long afterglow (HLA) polymer films are fabricated using a facile molecular doping strategy. Flexible and transparent polymer films emitted a bright afterglow lasting over 11 h at room temperature in air, which is one of the best performances among the organic afterglow materials reported to date. Intriguingly, HLA polymer films can be activated by sunlight, and their cyan afterglow in air can be readily observed by the naked eye. Moreover, the HLA color of the polymer films could be tuned from cyan to red through the Förster resonance energy transfer mechanism. Their application in flexible displays and information storage has also been demonstrated. With remarkable advantages, including an hour-long and bright afterglow, tunable afterglow colors, superior flexibility and transparency, and ease of fabrication, the HLA polymer paves the way for the practical application of afterglow materials in the engineering sector.

13.
Artículo en Inglés | MEDLINE | ID: mdl-39150812

RESUMEN

Motion artifacts compromise the quality of magnetic resonance imaging (MRI) and pose challenges to achieving diagnostic outcomes and image-guided therapies. In recent years, supervised deep learning approaches have emerged as successful solutions for motion artifact reduction (MAR). One disadvantage of these methods is their dependency on acquiring paired sets of motion artifact-corrupted (MA-corrupted) and motion artifact-free (MA-free) MR images for training purposes. Obtaining such image pairs is difficult and therefore limits the application of supervised training. In this paper, we propose a novel UNsupervised Abnormality Extraction Network (UNAEN) to alleviate this problem. Our network is capable of working with unpaired MA-corrupted and MA-free images. It converts the MA-corrupted images to MA-reduced images by extracting abnormalities from the MA-corrupted images using a proposed artifact extractor, which intercepts the residual artifact maps from the MA-corrupted MR images explicitly, and a reconstructor to restore the original input from the MA-reduced images. The performance of UNAEN was assessed by experimenting with various publicly available MRI datasets and comparing them with state-of-the-art methods. The quantitative evaluation demonstrates the superiority of UNAEN over alternative MAR methods and visually exhibits fewer residual artifacts. Our results substantiate the potential of UNAEN as a promising solution applicable in real-world clinical environments, with the capability to enhance diagnostic accuracy and facilitate image-guided therapies. Our codes are publicly available at https://github.com/YuSheng-Zhou/UNAEN.

14.
Nano Lett ; 12(6): 3086-90, 2012 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-22594588

RESUMEN

We demonstrate a new type of integrated nanogenerator based on arrays of vertically aligned piezoelectric ZnO nanowires. The peak open-circuit voltage and short-circuit current reach a record high level of 58 V and 134 µA, respectively, with a maximum power density of 0.78 W/cm(3). The electric output was directly applied to a sciatic nerve of a frog, inducing innervation of the nerve. Vibrant contraction of the frog's gastrocnemius muscle is observed as a result of the instantaneous electric input from the nanogenerator.


Asunto(s)
Potenciales de Acción/fisiología , Terapia por Estimulación Eléctrica/instrumentación , Sistemas Microelectromecánicos/instrumentación , Nanotecnología/instrumentación , Nervio Ciático/fisiología , Óxido de Zinc/química , Animales , Diseño de Equipo , Análisis de Falla de Equipo , Ranidae , Integración de Sistemas
15.
Nano Lett ; 12(9): 4960-5, 2012 Sep 12.
Artículo en Inglés | MEDLINE | ID: mdl-22889363

RESUMEN

By converting ambient energy into electricity, energy harvesting is capable of at least offsetting, or even replacing, the reliance of small portable electronics on traditional power supplies, such as batteries. Here we demonstrate a novel and simple generator with extremely low cost for efficiently harvesting mechanical energy that is typically present in the form of vibrations and random displacements/deformation. Owing to the coupling of contact charging and electrostatic induction, electric generation was achieved with a cycled process of contact and separation between two polymer films. A detailed theory is developed for understanding the proposed mechanism. The instantaneous electric power density reached as high as 31.2 mW/cm(3) at a maximum open circuit voltage of 110 V. Furthermore, the generator was successfully used without electric storage as a direct power source for pulse electrodeposition (PED) of micro/nanocrystalline silver structure. The cathodic current efficiency reached up to 86.6%. Not only does this work present a new type of generator that is featured by simple fabrication, large electric output, excellent robustness, and extremely low cost, but also extends the application of energy-harvesting technology to the field of electrochemistry with further utilizations including, but not limited to, pollutant degradation, corrosion protection, and water splitting.


Asunto(s)
Cristalización/métodos , Galvanoplastia/métodos , Nanopartículas del Metal/química , Nanopartículas del Metal/ultraestructura , Impresión Molecular/métodos , Plata/química , Sustancias Macromoleculares/química , Sustancias Macromoleculares/efectos de la radiación , Ensayo de Materiales , Nanopartículas del Metal/efectos de la radiación , Conformación Molecular/efectos de la radiación , Tamaño de la Partícula , Propiedades de Superficie/efectos de la radiación
16.
Nano Lett ; 12(6): 2833-8, 2012 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-22545631

RESUMEN

Harvesting thermoelectric energy mainly relies on the Seebeck effect that utilizes a temperature difference between two ends of the device for driving the diffusion of charge carriers. However, in an environment that the temperature is spatially uniform without a gradient, the pyroelectric effect has to be the choice, which is based on the spontaneous polarization in certain anisotropic solids due to a time-dependent temperature variation. Using this effect, we experimentally demonstrate the first application of pyroelectric ZnO nanowire arrays for converting heat energy into electricity. The coupling of the pyroelectric and semiconducting properties in ZnO creates a polarization electric field and charge separation along the ZnO nanowire as a result of the time-dependent change in temperature. The fabricated nanogenerator has a good stability, and the characteristic coefficient of heat flow conversion into electricity is estimated to be ∼0.05-0.08 Vm(2)/W. Our study has the potential of using pyroelectric nanowires to convert wasted energy into electricity for powering nanodevices.


Asunto(s)
Suministros de Energía Eléctrica , Nanoestructuras/química , Nanoestructuras/ultraestructura , Transductores , Óxido de Zinc/química , Transferencia de Energía , Diseño de Equipo , Análisis de Falla de Equipo , Calor
17.
Int J Disaster Risk Reduct ; 91: 103688, 2023 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-37089615

RESUMEN

The ongoing coronavirus pandemic has been threatening the healthcare system. In this context, telehealth is a potential solution to deliver effective and safe health care to the public. To facilitate the application and acceptance of telehealth, a good understanding of psychological determinants is of great importance. Therefore, this study aims to examine the public's positive and negative mindsets towards telehealth. A theoretical model was established by employing the technology readiness model and perceived value theory. To empirically test the relationships between constructs, a total of 500 responses from residents in Singapore were collected; thereafter, structural equation modeling was performed. The results indicate that discomfort negatively impacts perceived value whereas optimism and innovativeness positively impact users' perceived value. Further, perceived value positively impacts the acceptance of telehealth via attitude. Demographic factors (i.e. internet literacy, age, education) can also influence certain aspects of technology readiness (e.g. innovativeness, optimism). Moreover, social influence is an important moderator between perceived value and the acceptance of telehealth. The empirical findings enhance the understanding of users' psychology concerning telehealth and provide policy recommendations regarding the development of telehealth to improve public health.

18.
Materials (Basel) ; 16(2)2023 Jan 05.
Artículo en Inglés | MEDLINE | ID: mdl-36676254

RESUMEN

In this paper, five grading functional gradient lattice structures with a different density perpendicular to the loading direction were proposed, and the surface morphology, deformation behavior, and compression properties of the functional gradient lattice structures prepared by selective laser melting (SLM) with Ti-6Al-4V as the building material were investigated. The results show that the characteristics of the laser energy distribution of the SLM molding process make the spherical metal powder adhere to the surface of the lattice structure struts, resulting in the actual relative density of the lattice structure being higher than the designed theoretical relative density, but the maximum error does not exceed 3.33%. With the same relative density, all lattice structures with density gradients perpendicular to the loading direction have better mechanical properties than the uniform lattice structure, in particular, the elastic modulus of LF, the yield strength of LINEAR, and the first maximum compression strength of INDEX are 28.99%, 16.77%, and 14.46% higher than that of the UNIFORM. In addition, the energy absorption per unit volume of the INDEX and LINEAR is 38.38% and 48.29% higher, respectively, than that of the UNIFORM. Fracture morphology analysis shows that the fracture morphology of these lattice structures shows dimples and smooth planes, indicating that the lattice structure exhibits a mixed brittle and ductile failure mechanism under compressive loading. Finite element analysis results show that when the loading direction is perpendicular to the density gradient-forming direction, the higher density part of the lattice structure is the main bearing part, and the greater the density difference between the two ends of the lattice structure, the greater the elastic modulus.

19.
ACS Omega ; 8(21): 18400-18407, 2023 May 30.
Artículo en Inglés | MEDLINE | ID: mdl-37273628

RESUMEN

With the growing demand for gasoline and diesel fuel and the shortage of conventional oil reserves, there has been extensive interest in upgrading technologies for unconventional feedstocks such as heavy oil. Slurry bed reactors with high tolerance to heavy oil have been extensively investigated. Among them, dispersive MoS2 is favored for its excellent hydrogenation ability for heavy oil even under harsh reaction conditions such as high pressure and high temperature, its ability to effectively prevent damage to equipment from deposited coke, and its ability to meet the requirement of high catalyst dispersion for slurry bed reactors. This paper reviews the relationship between the structure and hydrogenation effectiveness of dispersive molybdenum disulfide, the hydrogenation mechanism, and the improvement of its hydrogenation performance by adding defects and compares the application of molybdenum disulfide in heavy oil hydrogenation, desulfurization, deoxygenation, and denitrification. It is found that the current research on dispersive molybdenum disulfide catalysts focuses mostly on the reduction of stacking layers and catalytic performance, and there is a lack of research on the lateral dimensions, microdomain regions, and defect sites of MoS2 catalysts. The relationship between catalyst structure and hydrogenation effect also lags far behind the application of MoS2 in the precipitation of hydrogen, etc. Oil-soluble and water-soluble MoS2 catalysts eventually need to be converted to a solid sulfide state to have hydrogenation activity. The conversion history of soluble catalysts to solid-type catalysts and the key to their improved catalytic effectiveness remain unclear.

20.
Cell Biosci ; 13(1): 218, 2023 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-38037169

RESUMEN

BACKGROUND: L-ascorbic acid (Asc) plays a pivotal role in regulating various biological processes, including somatic cell reprogramming, through multiple pathways. However, it remains unclear whether Asc regulates reprogramming directly or functions through its metabolites. RESULTS: Asc exhibited dual capabilities in promoting reprogramming through both 2,3-diketo-L-gulonic acid (DKG), a key metabolite during Asc degradation, dependent and independent routes. On the one hand, Asc facilitated reprogramming by promoting cell proliferation and inducing the conversion from pre-induced pluripotent stem cells (pre-iPSCs) to iPSCs through DKG-independent pathways. Additionally, Asc triggered mesenchymal-epithelial transition (MET) and activated glycolysis via DKG-dependent mechanisms. Notably, DKG alone activated a non-canonical tricarboxylic acid cycle characterized by increased succinate, fumarate, and malate. Consequently, this shift redirected oxidative phosphorylation toward glycolysis and induced MET. Moreover, owing to its antioxidant capabilities, Asc directly inhibited glycolysis, thereby preventing positive feedback between glycolysis and epithelial-mesenchymal transition, ultimately resulting in a higher level of MET. CONCLUSION: These findings unveil the intricate functions of Asc in the context of reprogramming. This study sheds light on the DKG-dependent and -independent activities of Asc during reprogramming, offering novel insights that may extend the application of Asc to other biological processes.

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