In this study, using coconut fibers as raw material, activated carbon fibers were prepared
via
carbonization and KOH activation processes. The morphology, composition, specific surface area, pore ...structure and thermal stability of the resulting activated carbon fibers were systematically characterized. It was found that the activation process increases the specific surface area of carbon fibers to a greater extent
via
formation of a large number of micropores (0.7-1.8 nm) and a certain amount of slit-shaped mesopores (2-9 nm). The specific surface area and the pore volume of the activated carbon fibers reach 1556 m
2
g
−1
and 0.72 cm
3
g
−1
, respectively. The activation process can also decompose the tar deposits formed after the carbonization process by pyrolysis, making the surface of the activated carbon fibers smoother. To study the adsorption properties of the as-prepared activated carbon fibers, the adsorption capacities and adsorption kinetics of various organic dyes including methylene blue, Congo red and neutral red were investigated. The adsorption capacities of the dyes increased with the increasing initial dye concentrations, and varied greatly with the pH value of the system. In methylene blue and neutral red systems, the adsorption capacities reach the maximum at pH 9, and in the Congo red system, it reaches the maximum at pH 3. The adsorption capacities of the activated carbon fibers in methylene blue, Congo red and neutral red systems reached equilibrium at 150, 120, and 120 min, and the maximum adsorption capacities were 21.3, 22.1, and 20.7 mg g
−1
, respectively. The kinetics of the adsorption process was investigated using three models including pseudo-first-order, pseudo-second-order and intraparticle diffusion models. The results indicated that the dynamic adsorption processes of coconut-based activated carbon fibers to methylene blue, Congo red and neutral red were all in accordance with the second-order kinetic model, and the equations are as follows:
t
/
Q
t
= 0.1028 +
t
/21.3220,
t
/
Q
t
= 0.1128 +
t
/21.5982 and
t
/
Q
t
= 0.0210 +
t
/20.6612.
Activated carbon fibers with high micropore volume and large specific surface area were prepared from abundant and low-cost coconut fibers, which show excellent adsorption performances towards various dyes.
•In recent years, China has prioritized ecological security (ES)•An improved ecological footprint model can effectively assess ecological security.•Poor ES is found in eastern coastal areas and the ...second-third step boundary.•China should consider ES, energy security, and food security in future development.
With the outbreak of the current global eco-environmental crisis, ensuring global and local ecological security (ES) has become a priority for many countries in the world. In the past few decades, social and economic development in China has induced many ecological and environmental problems, which have negatively impacted ES of China and the world. In recent years, with the increasing awareness of China’s ecological and environmental protection, the Chinese government has actively participated in global ecological and environmental governance and raised ES to the height of national security. A systematic and comprehensive assessment of ES is the basis of ES assurance, which can enable governments to accurately grasp the ES status of different regions and adopt targeted management measures. The ecological footprint (EF) model is a mature model that has been widely used for ES assessment. Thus, this study used an EF model with localized parameters analyzing the spatiotemporal changes in China’s ES from 2006 to 2016 on a provincial scale. Then, from an “occupation-carrying” perspective, this study explored the main aspect that induced changes in regional ES and identified the main type of ecological land that threatened regional ES. Results showed that a) during the study period, China’s ES status showed a deteriorating trend and the current ES is not optimistic. However, the ecological carrying capacity of most provinces in China has increased, indicating that China’s ecological and environmental protection has achieved initial results; b) currently, the provinces whose ES status are moderate unsafe and quite unsafe are mainly distributed in the eastern coastal region and the region near the boundary between the second and third ladders; c) the high-intensity occupation of the ecological environment and biological resources attributed to the rapid development of the social economy is the main cause for the negative changes in ES in most areas; d) for most provinces in China, cropland occupation and fossil energy consumption pose great threats to the regional ES status. China should jointly consider ES, energy security, and food security in its future development plans.
Five‐membered N‐heterocycles play an important role in organic synthesis and material chemistry, as they are widespread through pharmaceutical molecules and natural products. Chemists have developed ...many synthetic strategies for constructing five‐membered N‐heterocycles from N‐centered radicals, but the availability of mild and green methods for these transformations is still limited. The cyclization of visible‐light‐generated N‐centered radicals with alkenes has emerged as a powerful tool to enable these chemical transformations in recent years. Through chosen representative examples, the significant developments in this promising field were outlined, including the selection of catalysts, substrate scope, mechanistic understanding (especially density functional theory calculations), and applications. The contents of this Minireview are categorized by intramolecular cyclization and intermolecular N‐centered radical addition/cyclization reactions.
N‐heterocycles: The cyclization of visible‐light‐generated N‐centered radicals with alkenes has emerged as a powerful tool for constructing five‐membered N‐heterocycles. Through chosen representative examples, the significant developments in this promising field are outlined, including the selection of catalysts, substrate scope, mechanistic understanding (especially density functional theory calculations), and applications.
Breast cancer (BC) is a common malignancy worldwide. More than 3 700 000 women die of BC every year. DSCAM‐AS1 was overexpressed several kinds of cancer and miR‐204‐5p was lowly expressed, which ...indicated that miR‐204‐5p had anti‐tumor activity and DSCAM‐AS1 had pro‐tumor activity. We intended to analyze DSCAM‐AS1, miR‐204‐5p, and ribonucleotide reductase M2 (RRM2). Microarray analysis and quantitative Real Time fluorescence Polymerase Chain Reaction (qRT‐PCR) were employed to determine DSCAM‐AS1 and miR‐204‐5p expression. Luciferase reporter assay was applied to examine the target relationship between DSCAM‐AS1, miR‐204‐5p, and RRM2. Cell Counting Kit‐8 (CCK‐8 assay), transwell assay, and flow cytometry were used to detect cell proliferation, invasion, and apoptosis. The expression of DSCAM‐AS1, miR‐204‐5p, and RRM2 were confirmed by Western blot. We also conducted in vivo assay to verify the effect of DSCAM‐AS1. DSCAM‐AS1 was up‐regulated, while miR‐204‐5p was down‐regulated in BC tissues and cells. DSCAM‐AS1 directly targeted miR‐204‐5p. DSCAM‐AS1 promoted the proliferation and invasion of BC cells by reducing miR‐204‐5p and inhibiting miR‐204‐5p expression. DSCAM‐AS1 expression was related to the expression of RRM2, and miR‐204‐5p could reverse the function of DSCAM‐AS1. RRM2 was up‐regulated in BC cells, and miR‐204‐5p inhibited RRM2 expression by targeting RRM2. Overexpression of RRM2 stimulated proliferation and cell invasion and impeded apoptosis. In vivo experiments showed that knockdown of DSCAM‐AS1 decreased the tumorigenesis of BC cells, increased the expression of miR‐204‐5p. DSCAM‐AS1 promoted proliferation and impaired apoptosis of BC cells by reducing miR‐204‐5p and enhancing RRM2 expression. DSCAM‐AS1/miR‐204‐5p/RRM2 may serve as novel therapeutic targets for BC.
Heat and mass transports through a rough surface are among the most fundamental and important phenomena in either natural or engineering problems. In this paper, theoretical modelling and direct ...simulation Monte Carlo method are employed to study the heterogeneous reaction–diffusion features induced by microscale roughness which is comparable to the molecular mean free path of the ambient gas. A quasi-one-dimensional homogeneous model is proposed, and it consists of an external diffusion region outside the roughness elements and an internal reaction–diffusion region which could be equivalent to a smooth surface with an effective chemical property. The external macroscopic diffusion can be characterized by a non-equilibrium criterion – the Damköhler number. The internal diffusion in micro-cavities must be analysed by considering the rarefied gas effects on the diffusivity, and another non-equilibrium criterion, the Thiele number, is introduced to evaluate the effective boundary condition imposed on the external region. Analytical formulae based on these criteria are derived to predict the equivalent surface reaction–diffusion performance, and the predictions compare well with the numerical results of different types of surface reaction, even on the three-dimensional roughness. This reveals that the roughness could either enhance or weaken the apparent reaction rate depending on the non-equilibrium degree. This study could enrich our understanding of the gas–surface interactions on a rough wall, such as the oxidation, catalysis and energy accommodation, and also preliminarily provides a practical method for evaluation of the aerothermochemical performance of coating materials of hypersonic vehicles.
Background and Aims
Hepatic ischemia‐reperfusion (I/R) injury, which mainly involves inflammatory responses and apoptosis, is a common cause of organ dysfunction in liver transplantation (LT). As a ...critical mediator of inflammation and apoptosis in various cell types, the role of tripartite motif‐containing (TRIM) 27 in hepatic I/R injury remains worthy of study.
Approach and Results
This study systemically evaluated the putative role of TRIM27/transforming growth factor β–activated kinase 1 (TAK1)/JNK (c‐Jun N‐terminal kinase)/p38 signaling in hepatic I/R injury. TRIM27 expression was significantly down‐regulated in liver tissue from LT patients, mice subjected to hepatic I/R surgery, and hepatocytes challenged by hypoxia/reoxygenation (H/R) treatment. Subsequently, using global Trim27 knockout mice (Trim27‐KO mice) and hepatocyte‐specific Trim27 transgenic mice (Trim27‐HTG mice), TRIM27 functions to ameliorate liver damage, reduce the inflammatory response, and prevent cell apoptosis. In parallel in vitro studies, activating TRIM27 also prevented H/R‐induced hepatocyte inflammation and apoptosis. Mechanistically, TRIM27 constitutively interacted with the critical components, TAK1 and TAK1 binding protein 2/3 (TAB2/3), and promoted the degradation of TAB2/3, leading to inactivation of TAK1 and the subsequent suppression of downstream JNK/p38 signaling.
Conclusions
TRIM27 is a key regulator of hepatic I/R injury by mediating the degradation of TAB2/3 and suppression of downstream TAK1‐JNK/p38 signaling. TRIM27 may be a promising approach to protect the liver against I/R‐mediated hepatocellular damage in transplant recipients.
Detecting load parameters in the inductive power transfer (IPT) system is essential to establishing a stable and efficient wireless power supply of good quality for kitchen appliances. This paper ...presents an effective load detection approach, namely transient load detection model, to detect load conditions by utilizing the energy injection mode and free resonant mode. To realize the proposed model, the differential equation of the primary resonant current under the free resonant mode was used. Besides, real-time sampled data, including the operating frequency in the free resonant mode and peak value of the primary resonant current were collected. Imitating the wireless power supply for kitchen appliances, simulation and experimental results with the full-bridge SS-type voltage-fed IPT system have shown that this transient load detection model is accurate and reliable.
Summary
In this paper, three new kinds of time‐domain numerical methods of exponentially damped systems are presented, namely, the simplified Newmark integration method, the precise integration ...method, and the simplified complex mode superposition method. Based on the traditional Newmark integration method and transforming the equation of motion with exponentially damping kernel functions into an equivalent second‐order equation of motion by using the internal variables technique, the simplified Newmark integration method is developed by using a decoupling technique to reduce the computer run time and storage. By transforming the equation of motion with exponentially damping kernel functions into a first‐order state‐space equation, the precise integration technique is used to numerically solve the state‐space equation. Based on a symmetric state‐space equation and the complex mode superposition method, a delicate and simplified general solution of exponentially damped linear systems, completely in real‐value form, is developed. The accuracy and efficiency of the developed numerical methods are compared and discussed by two benchmark examples.
A shared physical communications channel is designed and implemented in this paper for inductive (contactless) power transfer (IPT) applications, wherein data are transferred without interfering ...power transfer, and, thus, maintained the efficiency of the IPT system. The channel is made of coupling coils, which are used to control the system and to transfer data bidirectionally at the rate of 19.2 Kb/s. To make the system work in two relatively independent modes, the wave trappers (passive bandpass and band-reject filters) are added into the system, and an integrated mathematical model is established based on separate models of data and power transfer. The proposed method was tested on a laboratory scale prototype, and was proved to be reliable for the parallel transmission of power and data. Therefore, the proposed method can be used to improve performance of the IPT system by precise control due to communication between the primary side and the pickup side.
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