Estrogen has been shown to contribute greatly to growth and development in endometrial cancer. And recent research has suggested that intratumoral production of estrogen may play important roles in this cancer tissue. On the other hand, pregnane X receptor (PXR), a new member of nuclear receptors, has been shown to mediate the genomic effects of steroid hormones, including estrogen and xenobiotics. And this receptor is thought to regulate the expression of the cytochrome P-450 3A (CYP3A) gene family, which plays important roles in the metabolism of endogenous steroids and xenobiotics. Various levels of PXR expression were found in endometrial cancer tissues but not normal tissues. Tissues showing high PXR expression showed significantly high expression of CYP3A4/7 and low expression of estrogen receptor (ER) compared with levels in tissues showing low PXR expression. In endometrial cancer cell lines, HEC-1 cells, which express high PXR and low ER and progesterone receptor, show a stronger transcriptional response of the PXR-CYP3A pathway to the PXR ligands, especially endocrine-disrupting chemical, than do Ishikawa cells. These data suggest that the steroid/xenobiotics metabolism in the tumor tissue through PXR-CYP3A pathway might play an important role, especially in alternative pathway for gonadal hormone and endocrine-disrupting chemical effects on endometrial cancer expressing low ER alpha.
As a state-of-the-art computational method for simulating rock fracturing and fragmentation, the combined finite-discrete element method (FDEM) has become widely accepted since Munzijia (2004) published his comprehensive book of FDEM. This study developed a generalpurpose graphic-processing-unit (GPGPU)-parallelized FDEM using the compute unified device architecture (CUDA) C/C++ based on the authors' former sequential two-dimensional (2D) and three-dimensional (3D) Y-HFDEM IDE (integrated development environment) code. The theory and algorithm of the GPGPU-parallelized 3D Y-HFDEM IDE code are first introduced by focusing on the implementation of the contact detection algorithm, which is different from that in the sequential code, contact damping and contact friction. 3D modelling of the failure process of limestone under quasi-static loading conditions in uniaxial compressive strength (UCS) tests and Brazilian tensile strength (BTS) tests are then conducted using the GPGPU-parallelized 3D Y-HFDEM IDE code. The 3D FDEM modelling results show that mixed-mode I-II failures are the dominant failure mechanisms along the shear and splitting failure planes in the UCS and BTS models, respectively, with unstructured meshes. Pure mode I splitting failure planes and pure mode II shear failure planes are only possible in the UCS and BTS models, respectively, with structured meshes. Subsequently, 3D modelling of the dynamic fracturing of marble in dynamic Brazilian tests with a split Hopkinson pressure
We have developed a new class of highly-fluorescent blue emitter for organic light-emitting diodes (OLEDs) consisting of tetrasubstituted pyrenes. From the analysis of the excited state diagrams of pyrene and its derivatives by molecular orbital calculations, we found that the new tetra-substituted pyrenes are highly fluorescent. OLEDs fabricated using the synthesized tetrasubstituted pyrenes as emitters showed high efficiency and good color purity. IntroductionSince the report of the first multilayer organic light-emitting-diode (OLED) in 1987 [ 1 ], considerable efforts have been made to utilize the OLEDs to full-color displays. It should be mentioned that development of efficient and pure red, green, and blue (RGB) emitters is considered to be one of the most important technologies in achieving this target, since the characteristics of an OLED highly depend on the emitter. Especially, blue emitters are indispensable for all OLED displays with any of full-color panel constitution such as array of RGB emitting OLEDs, fluorescent color changing media with blue OLEDs, and color filters with white emitting OLEDs.Polycyclic Aromatic Hydrocarbons (PAHs) are well known as a major group of organic fluorescent materials. Anthracene [2,3], naphthacene [ 4 ], perylene [ 5 ] and their derivatives (such as rubrene [6]) have been widely used as emitters in OLEDs for their promising fluorescent properties. However, pyrene, a basic PAH, has not attracted much attention as an OLED emitter because of its moderate fluorescence quantum yield (q F = 0.32 [7]) even in dilute solutions, and strong tendency to form excimer that leads to decrease the fluorescence efficiency in condensed media [8].In this report we explain the applicability of tetra-substituted pyrenes as blue emitters for OLEDs. It should be noted that unsubstituted pyrene is not a strong fluorescent emitter whereas 1,3,6,8-tetraphenylpyrene (tppy) has been measured to be highly fluorescent (q F = 0.90) in pure blue spectral region [7]. In this study, we analyzed the excited state diagrams of these molecules using molecular orbital (MO) method in order to understand the reason behind this remarkable change in fluorescent properties due to the introduction of phenyl moieties to pyrene. From this analysis, we understood that the tetra-substituted pyrenes are highly fluorescent. Here, we describe the excited-states analysis and the fluorescent properties of the pyrenes and the OLED performance of the devices using these compounds as emitters. Computational chemical surveyThe lowest singlet state of PAHs may be classified according to its electronic character determined by the perimeter free electron orbital model [7], into either L a state that is represented by the highest occupied molecular orbital (HOMO) to lowest unoccupied molecular orbital (LUMO) electronic transition, or L b state that is represented by a combination of the HOMO-1 to LUMO and HOMO to LUMO+1 transitions as given in Fig. 1. The L a state generally has strong oscillator strength (f) to the ground stat...
Surfaces of fine polystyrene (PS) and polymethyl methacrylate (PMMA) powders were modified by exposure to the downstream products of a nitrogen or oxygen microwave plasma. The effects of nitrogen and oxygen incorporation in the powder surface were studied with emphasis on variations in the triboelectric properties of the powder. X-ray photoelectron spectroscopy was utilized to determine the changes in surface elemental composition. After nitrogen plasma treatment, the C 1s peak shapes suggested the formation of amines in the case of PS, and the formation of imines and amides in the case of PMMA. Oxygen plasma treatment appears to result in the formation of hydroxyl and carbonyl groups on the surfaces of both PS and PMMA. After treatment with a nitrogen or oxygen plasma, the charge-to-mass ratio (Q/M) of PS and PMMA powders in contact with carrier particles was measured using the cage blowoff method. The surface charge density (Q/A) was calculated from Q/M. The Q/A of nitrogen plasma-treated PS powder was seen to shift towards positive charge with small increases in the nitrogen concentration. The Q/A of oxygen plasma-treated PS powder initially shifted toward negative charge, but changed towards positive charge with higher oxygen concentrations. Plasma-treated PMMA powder showed a different behavior and the variation of Q/A on PMMA was much less than that of PS. Results suggest that triboelectrification of the polymer powder may be related to changes in the electrical surface states, and that nitrogen may act as a group V modifier within the PS surface.
In this study, to better simulate underground coal gasification (UCG), an artificial coal seam was constructed to use as a simulated underground gasifier, which comprised coal blocks excavated from the coal seam. This study reports the process and results of three independently designed experiments using coaxial-hole and linking-hole UCG models: a) a coaxial model using a coaxial pipeline as a gasification channel, b) a coaxial model using the coaxial pipeline combined with a bottom cross-hole, and c) a linking-hole model using a horizontal V-shaped cross-hole. In the present work, the fracturing activities and cavity growth inside the reactor were monitored with acoustic emission (AE) technologies. During the process, the temperature profiles, gas production rate, and gas content were measured successively. The results show that AE activities monitored during UCG process are significantly affected by operational variables such as feed gas rate, feed gas content, and linking-hole types. Moreover, the amount of coal consumed during UCG process were estimated using both of the stoichiometric approach and balance computation of carbon (C) based on the product gas contents. A maximum error of less than 10% was observed in these methods, in which the gas leakage was also considered. This demonstrates that the estimated results using the proposed stoichiometric approach could be useful for evaluating energy recovery during UCG.
Underground coal gasification (UCG) is a technique to recover coal energy without mining by converting coal into a valuable gas. Model UCG experiments on a laboratory scale were carried out under a low flow rate (6~12 L/min) and a high flow rate (15~30 L/min) with a constant oxygen concentration. During the experiments, the coal temperature was higher and the fracturing events were more active under the high flow rate. Additionally, the gasification efficiency, which means the conversion efficiency of the gasified coal to the product gas, was 71.22% in the low flow rate and 82.42% in the high flow rate. These results suggest that the energy recovery rate with the UCG process can be improved by the increase of the reaction temperature and the promotion of the gasification area.
During underground coal gasification (UCG) operations, evaluation of coal gasification cavity evolution and precise control of the underground reactor are important for efficient gasification. It is also essential to estimate the energy recovery of a UCG system and the whole gasification process to ensure an effective combustion and gasification rate. An experimental simulation of UCG using an artificial coal seam comprising a compacted broken coal block was conducted using ex situ UCG models. The main goal of the experiments was the establishment of evaluation methods for the gasification zone and energy recovery during UCG. To investigate the distribution and extent of fracture activity, and to evaluate the propagation of the combustion area in the UCG reactor, we used acoustic emissions (AE) monitoring. This was combined with traditional measurements of temperature variation and product gas content. This paper presents the results of AE analysis of the fracturing activities and damage mechanisms of the coal seam with respect to the UCG operations. From the results of AE source location, we found that the position and area of the crack concentration area, i.e., the gasification zone, can be inferred with comparative accuracy. This is important for in situ practical application of underground coal gasification. In addition, use of the distribution characteristics of AE information over time can also provide advanced warning, and help in timely adjustment of the operational parameters. The results of gas energy recovery were estimated with a proposed stoichiometric method based on measured product gas composition. Quantitative evaluation results include the gas quantities, coal consumption, and heating value yield of the produced synthesis gas. The coal consumption of the obtained energy recovery results also meets the estimated results when calculating the gasification volume with AE source locations (in an error range of about 10%). Therefore, the applied AE monitoring and gas energy recovery approaches may be considered attractive options for evaluating the coal gasification process and developing a safe and efficient UCG system.
Underground Coal Gasification (UCG) demands precise evaluation of the combustion area in the coal seam. Especially, the monitoring of fracture activity in the coal seam and around rock is important not only for efficient gas production but also for estimation of subsidence and gas leakage to the surface. For this objective, laboratory experiments were conducted using the simulated UCG models. This paper also investigated gas energy for coal consumption, the production gas quantity and heat value, the application of oxygen element balance in the gasification reaction process, and the gas composition obtained in this study. During burning of the coal, temperatures inside the coal, contents of product gases and acoustic emission (AE) activities were monitored successively under the control of feeding gas (air/oxygen and steam) flow rate. Comparison of the temperature variation and accumulated AE event curves revealed a close correlation between them. The local change of temperature inside the coal induced fractures with AE. The AE activity was related closely to the local changes of temperature inside the model. The evaluation of gas energy recovery calculated from the obtained product gas provided a fair evaluation for the coal consumed, and the quantity of gas product and calorific value obtained from the UCG process.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.