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1.
BMC Med Educ ; 24(1): 404, 2024 Apr 11.
Artículo en Inglés | MEDLINE | ID: mdl-38605290

RESUMEN

OBJECTIVE: The present study aims to explore the influencing factors of the scientific fitness literacy of nurses and provide a strategic basis for literacy improvement. METHODS: A questionnaire on the influencing factors of scientific fitness literacy of nurses was designed by the group conducting the present study; the questionnaire was based on the socioecology model and the questionnaire preparation method. The general data questionnaire and the questionnaire on the influencing factors of scientific fitness literacy of nurses were adopted to investigate nurses in tertiary hospitals in order to analyze and discuss the influencing factors of their scientific fitness literacy. RESULTS: (1) The questionnaire on the influencing factors of the scientific fitness literacy of nurses comprised five dimensions and 36 items. The overall item-content validity index was 0.833-1.000, the scale-content validity index was 0.974, and the overall Cronbach's α coefficient was 0.955; (2) the results of the pairwise Pearson correlation analysis showed that all five dimensions were positively correlated with the scientific fitness literacy of nurses; and (3) the results of the multiple linear regression analysis revealed that five dimensions, as well as the existence of exercise habits in daily life, had a significant impact on the scientific fitness literacy of nurses (P < 0.001). CONCLUSION: The factors influencing the scientific fitness literacy of nurses involved all levels of the socioecological system. The methods of improving the awareness of the scientific fitness of nurses and providing opportunities for scientific fitness activities via the hospital played a critical role in literacy improvement. However, the lack of professional guidance and an atmosphere promoting scientific fitness might hinder literacy improvement.


Asunto(s)
Alfabetización en Salud , Humanos , Reproducibilidad de los Resultados , Alfabetización en Salud/métodos , Centros de Atención Terciaria , Encuestas y Cuestionarios
2.
Environ Sci Technol ; 2023 Jan 06.
Artículo en Inglés | MEDLINE | ID: mdl-36608262

RESUMEN

The distributed consensus mechanism is the backbone of the rapidly developing blockchain network. Blockchain platforms consume vast amounts of electricity based on the current consensus mechanism of Proof-of-Work (PoW). Here, we point out a different consensus mechanism named Proof-of-Stake (PoS) that can eliminate the extensive energy consumption of the current PoW-based blockchain. We comprehensively elucidate the current and projected energy consumption and carbon footprint of the PoW- and PoS-based Bitcoin and Ethereum blockchain platforms. The model of energy consumption of PoS-based Ethereum blockchain can lead the way toward the prediction of other PoS-based blockchain technologies in the future. With the widespread adoption of blockchain technology, if the current PoW mechanism continues to be employed, the carbon footprint of Bitcoin and Ethereum will push the global temperature above 1.5 °C in this century. However, a PoS-based blockchain can reduce the carbon footprint by 99% compared to the PoW mechanism. The small amount of carbon footprint from PoS-based blockchain could make blockchain an attractive technology in a carbon-constrained future. The study sheds light on the urgency of developing the PoS mechanism to solve the current sustainability problem of blockchain.

3.
BMC Cancer ; 21(1): 180, 2021 Feb 19.
Artículo en Inglés | MEDLINE | ID: mdl-33607955

RESUMEN

BACKGROUND: Aberrant activation of the Wnt/ß-catenin signaling pathway is one of the most frequent abnormalities in human cancer, including colorectal cancer (CRC). Previous studies revealed pivotal functions of WNT family members in colorectal cancer, as well as their prognostic values. Nevertheless, the prognostic role and mechanisms underlying WNT7b in colorectal cancer development remains unclear. METHODS: In this study, WNT7b expression was measured by immunohistochemical staining of 100 cases of surgically resected human colorectal cancerous tissues as well as matched adjacent normal tissues constructed as tissue microarrays. In vitro studies, we attempted to substantiate the WNT7b expressional pattern previously found in immunohistochemistry staining. We used the colorectal cancer cell-line HCT116 and normal colorectal cell-line FHC for immunofluorescence staining and nuclear/cytoplasmic separated western blotting. We measured epithelial-mesenchymal transition (EMT) markers and migration capacity of HCT116 in the context of WNT7b knocked-down using short interfering RNA. Finally, clinical and prognostic values of WNT7b activation levels were examined. RESULTS: WNT7b was expressed in the nucleus in adjacent normal tissues. In CRC tissues, nuclear expression of WNT7b was similar; however, membrane and cytoplasmic expression was strikingly enhanced. Consistently, in vitro analysis confirmed the same expression pattern of WNT7b. Compared with FHC cells, HCT116 cells displayed higher levels of WNT7b membrane and cytoplasmic enrichment, as well as higher migration capacity with a sensitized EMT process. Either partial knockdown of WNT7b or blockade of the Wnt/ß-catenin signaling pathway reversed EMT process and inhibited the migration of HCT116 cells. Finally, elevated secretion levels of WNT7b were significantly associated with lymphatic and remote metastasis and predicted worse prognosis in the CRC cohort. CONCLUSION: In summary, we demonstrated that the activation of WNT7b autocrine probably contributes to CRC metastasis by triggering EMT process through the Wnt/ß-catenin signaling pathway. High levels of WNT7b autocrine secretion predicts poor outcome in patients with CRC. This molecule is a promising candidate for clinical CRC treatments.


Asunto(s)
Neoplasias Colorrectales/metabolismo , Proteínas Wnt/metabolismo , Vía de Señalización Wnt , Anciano , Anciano de 80 o más Años , Línea Celular , Línea Celular Tumoral , Movimiento Celular , Proliferación Celular , Neoplasias Colorrectales/patología , Neoplasias Colorrectales/cirugía , Transición Epitelial-Mesenquimal , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Masculino , Persona de Mediana Edad , Metástasis de la Neoplasia , Pronóstico , Tasa de Supervivencia
4.
Environ Sci Technol ; 55(4): 2628-2638, 2021 02 16.
Artículo en Inglés | MEDLINE | ID: mdl-33529528

RESUMEN

Groundwater contamination by halogenated organic compounds, especially fluorinated ones, threatens freshwater sources globally. Sulfidized nanoscale zero-valent iron (SNZVI), which is demonstrably effective for dechlorination of groundwater contaminants, has not been well explored for defluorination. Here, we show that SNZVI nanoparticles synthesized via a modified post-sulfidation method provide rapid dechlorination (∼1100 µmol m-2 day-1) and relatively fast defluorination (∼6 µmol m-2 day-1) of a halogenated emerging contaminant (florfenicol) under ambient conditions, the fastest rates that have ever been reported for Fe0-based technologies. Batch reactivity experiments, material characterizations, and theoretical calculations indicate that coating S onto the metallic Fe surface provides a highly chemically reactive surface and changes the primary dechlorination pathway from atomic H for nanoscale zero-valent iron (NZVI) to electron transfer for SNZVI. S and Fe sites are responsible for the direct electron transfer and atomic H-mediated reaction, respectively, and ß-elimination is the primary defluorination pathway. Notably, the Cl atoms in florfenicol make the surface more chemically reactive for defluorination, either by increasing florfenicol adsorption or by electronic effects. The defluorination rate by SNZVI is ∼132-222 times higher with chlorine attached compared to the absence of chlorine in the molecule. These mechanistic insights could lead to new SNZVI materials for in situ groundwater remediation of fluorinated contaminants.


Asunto(s)
Agua Subterránea , Tricloroetileno , Contaminantes Químicos del Agua , Hierro , Azufre , Tianfenicol/análogos & derivados , Agua
5.
Phys Chem Chem Phys ; 23(27): 14811-14817, 2021 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-34212971

RESUMEN

Hydration of ions/molecules in nanometer-sized clusters or nanoscopic pores is ubiquitous and plays a key role in many chemical and physical systems. In this work, guanidine-H2O reactions with n = 1-8 water molecules were systematically studied by ab initio methods. The result suggests that the reduced availability of water molecules greatly inhibits the strong base guanidine from producing OH-. That is, guanidine exhibits the behavior of a weak bases in low-humidity nanoscale environments. Intriguingly, this effect is not limited to guanidine but could be applied to other strong bases. Furthermore, we demonstrate that the direction of guanidine-CO2 reactions can be controlled by changing the number of water molecules present, which in turn responds to the humidity change in air. These findings not only shed some light on unconventional chemical reactions of strong bases in atmospheric clusters and on solid porous surfaces, but also provide insights into the development of guanidine-based CO2 air-capture sorbents.

6.
J Cell Mol Med ; 24(18): 10560-10572, 2020 09.
Artículo en Inglés | MEDLINE | ID: mdl-32779876

RESUMEN

Our previous studies found overexpression of Musashi2 (MSI2) conduced to the progression and chemoresistance of pancreatic cancer (PC) by negative regulation of Numb and wild type p53 (wtp53). Now, we further investigated the novel signalling involved with MSI2 in PC. We identified inositol-3-phosphate synthase 1 (ISYNA1) as a novel tumour suppressor regulated by MSI2. High MSI2 and low ISYNA1 expression were prevalently observed in 91 PC tissues. ISYNA1 expression was negatively correlated with MSI2 expression, T stage, vascular permeation and poor prognosis in PC patients. What's more, patients expressed high MSI2 and low ISYNA1 level had a significant worse prognosis. And in wtp53 Capan-2 and SW1990 cells, ISYNA1 was downregulated by p53 silencing. ISYNA1 silencing promoted cell proliferation and cell cycle by inhibiting p21 and enhanced cell migration and invasion by upregulating ZEB-1. However, MSI2 silencing upregulated ISYNA1 and p21 but downregulated ZEB-1, which can be rescued by ISYNA1 silencing. Moreover, reduction of cell migration and invasion resulting from MSI2 silencing was significantly reversed by ISYNA1 silencing. In summary, MSI2 facilitates the development of PC through a novel ISYNA1-p21/ZEB-1 pathway, which provides new gene target therapy for PC.


Asunto(s)
Carcinoma Ductal Pancreático/patología , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/fisiología , Liasas Intramoleculares/fisiología , Proteínas de Neoplasias/fisiología , Neoplasias Pancreáticas/patología , Proteínas de Unión al ARN/fisiología , Transducción de Señal/fisiología , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/fisiología , Adulto , Anciano , Carcinoma Ductal Pancreático/genética , Carcinoma Ductal Pancreático/mortalidad , Carcinoma Ductal Pancreático/secundario , Línea Celular Tumoral , Movimiento Celular , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/biosíntesis , Inhibidor p21 de las Quinasas Dependientes de la Ciclina/genética , Progresión de la Enfermedad , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Liasas Intramoleculares/antagonistas & inhibidores , Liasas Intramoleculares/biosíntesis , Liasas Intramoleculares/genética , Estimación de Kaplan-Meier , Neoplasias Hepáticas/secundario , Metástasis Linfática , Masculino , Persona de Mediana Edad , Invasividad Neoplásica , Proteínas de Neoplasias/antagonistas & inhibidores , Proteínas de Neoplasias/biosíntesis , Proteínas de Neoplasias/genética , Neoplasias Pancreáticas/genética , Neoplasias Pancreáticas/mortalidad , Pronóstico , Interferencia de ARN , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/farmacología , Proteína p53 Supresora de Tumor/fisiología , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/biosíntesis , Homeobox 1 de Unión a la E-Box con Dedos de Zinc/genética
7.
J Aging Phys Act ; 28(6): 952-961, 2020 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-32702663

RESUMEN

The study's aims were to translate the Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire to Chinese and examine its psychometric properties. Adapting it for use in China involved forward translation, synthesis, back translation, expert review, and pretesting. A convenience sample of 201 Chinese older adults completed the Chinese version (CHAMPS-C) to evaluate its construct validity index and associations with physiological, psychosocial, and energy expenditure measures. The construct validity index of the CHAMPS-C was 0.95, and it had fair to moderate associations with physiological and psychosocial measures, other scales of physical activity, and accelerometer measurements. Our structured, stepwise process of cross-cultural adaptation produced a scale (i.e., CHAMPS-C), with items equivalent in meaning to the English version, for use with Chinese older adults. The findings of this study indicate that the CHAMPS-C has acceptable reliability and validity to assess the physical activity of older Chinese adults.

8.
Angew Chem Int Ed Engl ; 59(18): 6984-7006, 2020 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-31379037

RESUMEN

The urgency to address global climate change induced by greenhouse gas emissions is increasing. In particular, the rise in atmospheric CO2 levels is generating alarm. Technologies to remove CO2 from ambient air, or "direct air capture" (DAC), have recently demonstrated that they can contribute to "negative carbon emission." Recent advances in surface chemistry and material synthesis have resulted in new generations of CO2 sorbents, which may drive the future of DAC and its large-scale deployment. This Review describes major types of sorbents designed to capture CO2 from ambient air and they are categorized by the sorption mechanism: physisorption, chemisorption, and moisture-swing sorption.

9.
J Cell Physiol ; 234(12): 22260-22271, 2019 12.
Artículo en Inglés | MEDLINE | ID: mdl-31081124

RESUMEN

To better understand the molecular mechanisms of anaplastic thyroid carcinoma (ATC), we aimed to identify the hub genes specifically involved in ATC by integrated bioinformatics analysis. In this study, using three Gene Expression Omnibus data sets with the same platform GPL570, we screened hub genes involved in ATC progression. In vitro experiments, such as western blot analysis, Transwell assays, and coimmunoprecipitation, was performed to verify our findings. By comparing three subtypes of thyroid cancer with normal tissue, we found ATC harbored more changed genes than well and poorly differentiated thyroid cancer. Using specifically differentially expressed genes between ATC and normal thyroid tissues to perform Gene ontology (GO) analysis, ATC showed enrichments of GO terms involved in lymphocyte migration and activation, collagen catabolic and metabolic process, thyroid hormone synthesis, and embolism. Using genes involved in extracellular matrix, coexpression network analysis and protein-protein interaction analysis were performed to identify matrix metalloproteinase 3 (MMP3) and MMP13 as two hub genes. Our experimental data indicated that both MMP3 and MMP13 were upregulated in ATC and knockdown of either of them could notably suppress ATC cell invasion and migration. Mechanistically, Gene Set Enrichment Analysis, coimmunoprecipitation, and rescue experiments revealed MMP3 and MMP13 not only interacted with each other, but also regulated each other through the janus kinase/signal transducer and activator of transcription 3 and mammalian target of rapamycin pathways. In conclusion, we identified a specific molecular mechanisms for the development of ATC by integrated analysis of transcriptome and in vitro experiments, which suggested that MMP3 and MMP13 might be developed as novel therapeutic targets for ATC.


Asunto(s)
Progresión de la Enfermedad , Regulación Neoplásica de la Expresión Génica , Metaloproteinasa 13 de la Matriz/metabolismo , Metaloproteinasa 3 de la Matriz/metabolismo , Carcinoma Anaplásico de Tiroides/genética , Carcinoma Anaplásico de Tiroides/patología , Transcriptoma/genética , Línea Celular Tumoral , Movimiento Celular/genética , Ontología de Genes , Humanos , Quinasas Janus/metabolismo , Modelos Biológicos , Invasividad Neoplásica , Análisis de Componente Principal , Unión Proteica , Factor de Transcripción STAT3/metabolismo , Transducción de Señal , Serina-Treonina Quinasas TOR/metabolismo , Regulación hacia Arriba/genética
10.
BMC Cancer ; 19(1): 981, 2019 Oct 22.
Artículo en Inglés | MEDLINE | ID: mdl-31640615

RESUMEN

BACKGROUND: To our knowledge, there are no studies to systematically compare the detailed clinical significance between curatively resected pancreatic head (ph) and body-tail (pbt) ductal adenocarcinoma based on the new 8th edition of AJCC staging system (8th AJCC stage) that was just applied in clinical practice in 2018. METHODS: Three hundred fifty-one patients with curatively resected pancreatic adenocarcinoma (PC) from three center hospitals were entered into this multicenter cohort study. RESULTS: Increasing tumor size (P < 0.001), T stage (T1 + T2 vs T3 + T4, P = 0.003), frequent postoperative liver metastasis (PLM) (P = 0.002) and 8th AJCC stage (IA to VI, P < 0.001; I + II vs III + IV, P = 0.002) were closely associated with the progression of pbt cancers compared with that in ph cancer patients. Moreover, tumor size≥3 cm (P = 0.012), 8th AJCC stage (III + IV) (P = 0.025) and PLM (P = 0.010) were identified as independent risk factors in pbt cancers in logistic analysis. Patients with pbt cancers had a significantly worse overall survival compared with ph cancer patients (P = 0.003). Moreover, pbt was an independent unfavorable factor in multivariate analysis (P = 0.011). In addition to lymph nodes metastasis, 8th AJCC stage, vascular invasion and PLM, increasing tumor size and advanced T stage were also closely associated with the poor prognosis in 131 cases of pbt cancer patients compared with Ph cancer patients. CONCLUSION: Pbt, as an independent unfavorable factor for the prognosis of PC patients, are much more aggressive than that in ph cancers according to 8th AJCC staging system. 8th AJCC staging system are more comprehensive and sensitive to reflect the malignant biology of pbt cancers.


Asunto(s)
Carcinoma Ductal Pancreático/mortalidad , Carcinoma Ductal Pancreático/cirugía , Estadificación de Neoplasias/métodos , Pancreatectomía/métodos , Neoplasias Pancreáticas/mortalidad , Neoplasias Pancreáticas/cirugía , Anciano , Carcinoma Ductal Pancreático/clasificación , Carcinoma Ductal Pancreático/patología , China , Estudios de Cohortes , Femenino , Estudios de Seguimiento , Humanos , Estimación de Kaplan-Meier , Neoplasias Hepáticas/secundario , Metástasis Linfática , Masculino , Persona de Mediana Edad , Neoplasias Pancreáticas/clasificación , Neoplasias Pancreáticas/patología , Factores de Riesgo , Tasa de Supervivencia , Resultado del Tratamiento , Carga Tumoral
11.
Phys Chem Chem Phys ; 21(11): 5916-5924, 2019 Mar 13.
Artículo en Inglés | MEDLINE | ID: mdl-30534749

RESUMEN

The mechanical behaviors of a series of two-dimensional (2-D) crystals X3M2 (X = S, Se; M = N, P, As) are explored through density functional theory (DFT) calculations. Two atomic structures exist for 2-D X3M2, namely α-heart and ß-heart, which exhibit different out-of-plane Negative Poisson's Ratio (NPR) phenomena. For α-heart structures, a general out-of-plane NPR exists under in-plane tension in the y direction, while for ß-heart type structures, a general NPR exists under in-plane tension in the x direction. Through DFT calculations, we revealed that a NPR is a general phenomenon for 2-D X3M2 with heart-shaped atomic structures, and the absolute value of the out-of-plane NPR for 2-D X3M2 is always one order of magnitude larger than other 2-D crystals reported before. At the same time, the in-plane NPR at certain angles around two in-plane principal axes also exists for 2-D X3M2 except for S3P2 due to the special heart-shaped structure. The coexistence of out-of-plane and in-plane NPRs for 2-D crystals has not been reported before and these special three-dimensional (3-D) auxetic properties in 2-D crystals may enormously enrich research studies on novel mechanical, electrical and chemical behaviors of 2-D crystals. This discovery will extend the family of 2-D crystals with a NPR and also provide new insights for designing novel negative Poisson's ratio materials.

12.
Nanotechnology ; 29(8): 085707, 2018 Feb 23.
Artículo en Inglés | MEDLINE | ID: mdl-29300176

RESUMEN

A new phosphorous allotrope, closed-edged bilayer phosphorene nanoribbon, is proposed via radially deforming armchair phosphorene nanotubes. Using molecular dynamics simulations, the transformation pathway from round PNTs falls into two types of collapsed structures: arc-like and sigmoidal bilayer nanoribbons, dependent on the number of phosphorene unit cells. The fabricated nanoribbions are energetically more stable than their parent nanotubes. It is also found via ab initio calculations that the band structure along tube axis substantially changes with the structural transformation. The direct-to-indirect transition of band gap is highlighted when collapsing into the arc-like nanoribbons but not the sigmoidal ones. Furthermore, the band gaps of these two types of nanoribbons show significant size-dependence of the nanoribbon width, indicative of wider tunability of their electrical properties.

13.
Phys Chem Chem Phys ; 20(34): 21832-21843, 2018 Aug 29.
Artículo en Inglés | MEDLINE | ID: mdl-29922798

RESUMEN

The phase transition of monolayer black phosphorene (MBP, α-P) to ß-P and γ-P is explored by density functional theory (DFT) calculations and molecular dynamics (MD) simulations using reactive force fields. It is found that MBP can convert to a mixed phase of ß-P and γ-P under biaxial strain, while the Stone-Wales defect (SW-2) in MBP can serve as an excellent 'phase transition catalyzer', significantly decreasing the critical strain for phase transition and increasing the homogeneity of the phase transition. The biaxial strain state (i.e. the strain components in the armchair and zigzag direction) and loading mode (i.e. the proportional and staged loading) have significant effects on the phase transition of MBP. In general, the phase transition of MBP is driven by the tension strain in the armchair direction, but large tension or compression strain in the zigzag direction can also promote the phase transition. Besides, MBP has a larger fracture strain under staged loading, generating a more uniform phase transition structure. The effects of curvature and SW-2 defect concentration on the phase transition of MBP are also studied, which shows an easier phase transition for a larger curvature and higher SW-2 defect concentration. The systematic results presented herein provide useful insights for designing and tuning the structure of MBP through phase transition facilitated by strain and defect engineering.

14.
J Chem Phys ; 149(16): 164708, 2018 Oct 28.
Artículo en Inglés | MEDLINE | ID: mdl-30384735

RESUMEN

Ion hydration is a fundamental process in many natural phenomena. This paper presents a quantitative analysis, based on atomistic modeling, of the behavior of ions and the impact of hydration in a novel CO2 sorbent. We explore moisture-driven CO2 sorbents focusing on diffusion of ions and the structure of ion hydration complexes forming inside water-laden resin structures. We show that the stability of the carbonate ion is reduced as the water content of the resin is lowered. As the hydration cloud of the carbonate ion shrinks, it becomes energetically favorable to split a remaining water molecule and form a bicarbonate ion plus a hydroxide ion. These two ions bind less water than a single, doubly charged carbonate ion. As a result, under relatively dry conditions, more OH- ions are available to capture CO2 than in the presence of high humidity. Local concentrations of dissolved inorganic carbon and water determine chemical equilibria. Reaction kinetics is then driven to a large extent by diffusion rates that allow water and anions to move through the resin structure. Understanding the basic mechanics of chemical equilibria and transport may help us to rationally design next-generation efficient moisture-driven CO2 sorbents.

15.
Phys Chem Chem Phys ; 19(31): 20377-20382, 2017 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-28678264

RESUMEN

The self-assembly mechanism of one-end-open carbon nanotubes (CNTs) suspended in an aqueous solution was studied by molecular dynamics simulations. It was shown that two one-end-open CNTs with different diameters can coaxially self-assemble into a nanocapsule. The nanocapsules formed were stable in aqueous solution under ambient conditions, and the pressure inside the nanocapsule was much higher than the ambient pressure due to the van der Waals interactions between the two parts of the nanocapsule. The effects of the normalized radius difference, normalized inter-tube distance and aspect ratio of the CNT pairs were systematically explored. The electric field response of the nanocapsules was studied using ab initio molecular dynamics simulations, which shows that the nanocapsules can be opened by applying an external electric field, due to the polarization of carbon atoms. This discovery not only sheds light on a simple yet robust nanocapsule self-assembly mechanism, but also underpins potential innovations in drug delivery, nano-reactors, etc.

16.
Phys Chem Chem Phys ; 19(40): 27435-27441, 2017 Oct 18.
Artículo en Inglés | MEDLINE | ID: mdl-28975183

RESUMEN

The hydration of ions in nanoscale hydrated clusters is ubiquitous and essential in many physical and chemical processes. Here we show that the hydrolysis reaction is strongly affected by relative humidity. The hydrolysis of CO32- with n = 1-8 water molecules is investigated using an ab initio method. For n = 1-5 water molecules, all the reactants follow a stepwise pathway to the transition state. For n = 6-8 water molecules, all the reactants undergo a direct proton transfer to the transition state with overall lower activation free energy. The activation free energy of the reaction is dramatically reduced from 10.4 to 2.4 kcal mol-1 as the number of water molecules increases from 1 to 6. Meanwhile, the degree of hydrolysis of CO32- is significantly increased compared to the bulk water solution scenario. Incomplete hydration shells facilitate the hydrolysis of CO32- with few water molecules to be not only thermodynamically favorable but also kinetically favorable. We showed that the chemical kinetics is not likely to constrain the speed of CO2 air capture driven by the humidity-swing. Instead, the pore-diffusion of ions is expected to be the time-limiting step in the humidity driven CO2 air capture. The effect of humidity on the speed of CO2 air capture was studied by conducting a CO2 absorption experiment using IER with a high ratio of CO32- to H2O molecules. Our result is able to provide valuable insights into designing efficient CO2 air-capture sorbents.

17.
J Phys Chem A ; 121(32): 6135-6149, 2017 Aug 17.
Artículo en Inglés | MEDLINE | ID: mdl-28723088

RESUMEN

We developed ReaxFF parameters for phosphorus and hydrogen to give a good description of the chemical and mechanical properties of pristine and defected black phosphorene. ReaxFF for P/H is transferable to a wide range of phosphorus- and hydrogen-containing systems including bulk black phosphorus, blue phosphorene, edge-hydrogenated phosphorene, phosphorus clusters, and phosphorus hydride molecules. The potential parameters were obtained by conducting global optimization with respect to a set of reference data generated by extensive ab initio calculations. We extended ReaxFF by adding a 60° correction term, which significantly improved the description of phosphorus clusters. Emphasis was placed on the mechanical response of black phosphorene with different types of defects. Compared to the nonreactive SW potential ( Jiang , J.-W. Nanotechnology 2015 , 26 , 315706 ), ReaxFF for P/H systems provides a significant improvement in describing the mechanical properties of the pristine and defected black phosphorene, as well as the thermal stability of phosphorene nanotubes. A counterintuitive phenomenon is observed that single vacancies weaken the black phosphorene more than double vacancies with higher formation energy. Our results also showed that the mechanical response of black phosphorene is more sensitive to defects in the zigzag direction than that in the armchair direction. In addition, we developed a preliminary set of ReaxFF parameters for P/H/O/C to demonstrate that the ReaxFF parameters developed in this work could be generalized to oxidized phosphorene and P-containing 2D van der Waals heterostructures. That is, the proposed ReaxFF parameters for P/H systems establish a solid foundation for modeling of a wide range of P-containing materials.

18.
Chemistry ; 22(51): 18326-18330, 2016 Dec 19.
Artículo en Inglés | MEDLINE | ID: mdl-27762459

RESUMEN

A great deal of information exists concerning the hydration of ions in bulk water. Much less noticeable, but equally ubiquitous is the hydration of ions holding on to several water molecules in nanoscopic pores or in natural air at low relative humidity. Such hydration of ions with a high ratio of ions to water molecules (up to 1:1) are essential in determining the energetics of many physical and chemical systems. Herein, we present a quantitative analysis of the energetics of ion hydration in nanopores based on molecular modeling of a series of basic salts associated with different numbers of water molecules. The results show that the degree of hydrolysis of basic salts in the presence of a few water molecules is significantly different from that in bulk water. The reduced availability of water molecules promotes the hydrolysis of divalent and trivalent basic ions (S2- , CO32- , SO32- , HPO42- , SO42- , PO43- ), which produces lower valent ions (HS- , HCO3- , HSO3- , H2 PO4- , HSO4- , HPO42- ) and OH- ions. However, reducing the availability of water inhibits the hydrolysis of monovalent basic ions (CN- , HS- ). This finding sheds some light on a vast number of chemical processes in the atmosphere and on solid porous surfaces. The discovery has wide potential applications including designing efficient absorbents for acidic gases.

19.
Angew Chem Int Ed Engl ; 55(12): 4026-9, 2016 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-26914978

RESUMEN

Water confined in nanoscopic pores is essential in determining the energetics of many physical and chemical systems. Herein, we report a recently discovered unconventional, reversible chemical reaction driven by water quantities in nanopores. The reduction of the number of water molecules present in the pore space promotes the hydrolysis of CO3(2-) to HCO3(-) and OH(-). This phenomenon led to a nano-structured CO2 sorbent that binds CO2 spontaneously in ambient air when the surrounding is dry, while releasing it when exposed to moisture. The underlying mechanism is elucidated theoretically by computational modeling and verified by experiments. The free energy of CO3 (2-) hydrolysis in nanopores reduces with a decrease of water availability. This promotes the formation of OH(-), which has a high affinity to CO2 . The effect is not limited to carbonate/bicarbonate, but is extendable to a series of ions. Humidity-driven sorption opens a new approach to gas separation technology.

20.
Heart Lung ; 64: 182-188, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38281371

RESUMEN

BACKGROUND: Perception of exercise benefits/barriers and kinesiophobia are important predictors of low exercise behaviors in patients with cardiovascular diseases (CVDs). Little is known about the complex intercorrelations between different components of perception of exercise benefits/barriers and kinesiophobia. OBJECTIVES: To identify the central components of kinesiophobia and to explore the interconnectedness between perception of exercise benefits/barriers and kinesiophobia. METHODS: A total of 258 patients with CVDs were recruited in this study. The Tampa Scale for Kinesiophobia Heart and the Exercise Benefits/Barriers Scale were used to assess kinesiophobia and perception of exercise benefits/barriers. R software was used to visualize the networks and analyze the centrality of the networks. The index "expected influence" and "bridge expected influence" were employed to identify the central components and the bridge components of the networks. RESULTS: In the item network of kinesiophobia, three items ("It is really not safe for a person in my condition to be physically active/exercise", "I cannot do the same things as others because there is a too big risk that I will get heart problems", and "If I tried to be physically active/exercise my heart problem would increase") had the highest expected influence. In the exercise benefits/barriers-kinesiophobia network, the dimension of physical exertion had the highest positive bridge expected influence, while psychological outlook had highest negative value. CONCLUSIONS: The three central components of kinesiophobia and the two bridge components (perception exercise barriers of physical exertion and perception exercise benefits of psychological outlook) should be targeted in specific intervention for relieving kinesiophobia and further promoting exercise behaviors.


Asunto(s)
Enfermedades Cardiovasculares , Humanos , Miedo/psicología , Kinesiofobia , Ejercicio Físico , Percepción
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