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排序方式: 共有177条查询结果,搜索用时 15 毫秒
1.
A new standard mercury manometer has been developed to calibrate low vacuum gauges in the range from atmospheric pressure to 1 mbar. It consists of a cistern that is a small stainless steel container used as mercury reservoir and also as the first Hg column connected to a long glass tube used as the second Hg column. Manometer scale covers the difference in Hg heights in two columns up to the length equivalent to 1000 mbars. This is a novel low cost manometer with simple design, compact fabrication, better accuracy, easy operation, low vibration, and thermal stability. In order to evaluate the performance of the equipment, its generated pressures are compared with those of secondary standard, i.e., calibrated capacitance diaphragm gauge, giving the average correction factor 0.998. Different uncertainties of the generated pressures are discussed in detail along with the evaluation of correction factors. The relative uncertainty in the higher pressure side is found to be in the range of 10(-4) which is within the limit (approximately 10(-4)). 相似文献
2.
The thermal conductivity and thermal diffusivity of porous consolidated sandstones have been measured simultaneously by the
transient-plane source (TPS) technique in the temperature range from 280 to 330 K at ambient pressure using air as the saturant.
The porosity and density parameters are measured using standard American Society for Testing and Materials (ASTM) methods
at 307 ± 1 K. Data are presented for five types of samples ranging in porosity from 8 to 17 vol. %, taken from various positions
above the baseline. The thermal conductivity and constituents of the minerals vary with porosity as well as with the position
of the sample from the baseline. The thermal conductivity data are discussed in the framework of simple mixing laws and empirical
models. Simple correlations between the effective density and porosity, and between the effective thermal conductivity and
porosity, are also established 相似文献
3.
Liping Teng Maria Maqsood Min Zhu Yuting Zhou Mingzhu Kang Juan Zhou Jinghua Chen 《International journal of molecular sciences》2022,23(18)
Some scholars have suggested that the clinical application of exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs-exo) might represent a novel strategy to improve diabetic wound healing. However, the mechanisms underlying the effects of hucMSCs-exo on wound healing remain poorly understood. This study aimed to identify the mechanism of hucMSCs-exo in treating diabetic wounds. HucMSCs-exo were isolated from human umbilical cord mesenchymal stem cells (hucMSCs) and subcutaneously injected into full-thickness wounds in diabetic rats. Wound healing closure rates and histological analysis were performed. The levels of tumor necrosis factor-α (TNF-α), macrophage mannose receptor (MMR/CD206), platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), and vascular endothelial growth factor (VEGF) were detected by immunohistochemistry. The degree of collagen deposition was examined using Masson’s trichrome staining. Gross evaluation of wound healing was carried out from day 0 to 14 post-surgery, and the wound site was harvested for histology on days 3, 7, and 14 post-wounding. HucMSCs-exo transplantation increased diabetic wound healing. In vitro, hucMSCs-exo promoted the proliferation of human umbilical vein endothelial cells (HUVECs) and NIH-3T3 cells. In vivo, hucMSCs-exo reduced wound area and inflammatory infiltration and increased collagen fibers. In addition, wound tissues in the hucMSCs-exo group had higher CD206, CD31, and VEGF expressions and lower TNF-α levels than those in the control group on day 14. Our results demonstrated that hucMSCs-exo facilitated diabetic wound repair by inducing anti-inflammatory macrophages and promoting angiogenesis and collagen deposition. 相似文献
4.
Ahmad Jawad Khan Muazzam Ali Ahmed Fawad Khan Jan Sher 《Neural computing & applications》2018,30(12):3847-3857
Neural Computing and Applications - Content protection is considered as an important issue in today’s world. Therefore, encryption of such contents is a challenging task for researchers. They... 相似文献
5.
Kalsoom Anum Maqsood Muazzam Yasmin Sadaf Bukhari Maryam Shin Zian Rho Seungmin 《The Journal of supercomputing》2022,78(7):9668-9690
The Journal of Supercomputing - A multimedia-based medical decision-making system is an ultimate requirement in the medical imaging domain. In the healthcare sector, achieving quick and efficient... 相似文献
6.
Nowadays, people pay more and more emotional to the emotional analysis of specific goals. Due to the long training time of many networks, this paper proposes a neural network with specific Objective sentiment analysis. Compared with the current neural network, the algorithm proposed in this paper has a shorter training time, which can effectively make up for the lack of emotional mechanism. Finally, we use the emotional data set to carry out simulation experiments. The experimental results show that the proposed algorithm is better than the ordinary neural network algorithm.
相似文献7.
Khuram Maqsood Jayita Pal Dhanaraj Turunawarasu Anindya Jyoti Pal Saibal Ganguly 《Korean Journal of Chemical Engineering》2014,31(7):1120-1135
A novel concept of hybrid cryogenic distillation network has been explored which maximizes the benefits of both desublimation or solid-vapor based separation as well as distillation or vapor-liquid equilibrium based separation during the separation of carbon dioxide from methane or natural gas. Process network synthesis has been performed for four case studies with high carbon dioxide (72 mole%) and medium carbon dioxide (50 mole%) natural gas feed streams. The benefits of optimal locations for cryogenic packed beds were investigated. A conventional cryogenic network consisting of multiple distillation columns with butane as additive for extractive distillation was also studied and presented in this paper. Process modeling of cryogenic distillation network with MESH equations was attempted using an integrated dual loop (C+3) convergence and the results were compared with Aspen Plus simulator for benchmarking. The prediction of solidification region was employed using experimental data from literature to avoid solidification regions in the column. The proposed hybrid cryogenic distillation network showed promising potential for energy and size reduction. 相似文献
8.
A series of nanocrystalline Li0.25Ni0.5Fe2.25−xErxO4 (x=0.00, 0.02, 0.06, 0.08, and 0.10) ferrite powders, having a cubic spinel crystal structure and a low value of coercivity, was synthesized by the sol–gel auto-combustion route. The structure, morphology and magnetic properties of the prepared nanoferrites were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and the magnetic property measurement system (MPMS). A well-defined single phase spinel structure is confirmed in all the samples by X-ray diffraction analysis. The lattice parameters of the samples increase slightly with increasing the erbium content. The crystallite size of the Er-doped samples is smaller than that of pure Li–Ni ferrite, and decrease regularly in the range of 36.0–14.5 nm. It has been observed that the magnetic properties of these ferrites are strongly influenced by the added erbium content. The magnetic measurements indicate that saturation magnetization (Ms) and coercivity (Hc) decrease gradually with the increase of Er content in the lattice. 相似文献
9.
Katabathini Narasimharao Maqsood Ahmad MalikMohamed M. Mokhtar Sulaiman N. BasahelShaeel A. Al-Thabaiti 《Ceramics International》2014
Sulfated TiO2 nanotubes and a series of iron oxide loaded sulfated TiO2 nanotubes catalysts with different iron oxide loadings (1 wt%, 3 wt%, 5 wt% and 7 wt%) were prepared and calcined at 400 °C. The physico-chemical properties of the catalysts were studied by using XRD, N2-physisorption, Raman spectroscopy, SEM-EDX, TEM, XPS, and pyridine adsorption using FTIR and H2-TPR techniques. It was observed that iron oxide was highly dispersed on the sulfated TiO2 nanotube support due to its strong interaction. The activity of these catalysts in the catalytic removal of NO with propane was also studied in the temperature range of 300–500 °C. Highest activity (90% NO conversion) was observed with 5 wt% iron oxide supported on sulfated TiO2 catalyst at 450 °C. Selective catalytic reduction of NO activity of the catalysts was correlated with iron oxide loading, reducibility, and the Brönsted and Lewis acid sites of the catalysts. The catalyst also showed good stability under studied reaction conditions that no deactivation was observed during the 50 h of reaction. 相似文献
10.