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71.
A novel ceramic processing method, called Horizontal Dip Spin Casting (HDSC), enabled fabrication of tubular ceramic parts with an aligned chopped fiber phase. HDSC was demonstrated using highly loaded aqueous alumina suspensions with >50 vol.% solids loading and ≤5 vol.% water‐soluble polymer employed as a rheological modifier. Chopped carbon fibers were added to the suspensions to attain maximum loadings of 30 vol.%. During forming, cylindrical foam molds were dipped into the suspension while being rotated radially about the long axis. Simultaneously, a doctor blade was placed at a specified distance from the foam surface to facilitate the flow of the suspension to align the fiber and control the thickness of the material that accrued on the mold. Rheological study of alumina‐PVP suspensions with and without chopped carbon fiber showed that the suspensions exhibited a yield‐pseudoplastic flow behavior. The degree of alignment of the carbon fiber phase in the green bodies was characterized for various suspension formulations, carbon fiber contents and forming speeds. Stereological characterization of green body specimens confirmed the effectiveness of HDSC to attain the desired tubular geometry with considerable fiber alignment for a suspension composition containing ≤20 vol.% chopped fibers.  相似文献   
72.
Non‐aqueous extraction of bitumen from oil sands has the potential to reduce fresh water demand of the extraction process and eliminate tailings ponds. In this study, different light hydrocarbon solvents, including aromatics, cycloalkanes, biologically derived solvents and mixtures of solvents were compared for extraction of bitumen from Alberta oil sands at room temperature and ambient pressure. The solvents are compared based on bitumen recovery, the amount of residual solvent in the extracted oil sands tailings and the content of fine solids in the extracted bitumen. The extraction experiments were carried out in a multistage process with agitation in rotary mixers and vibration sieving. The oil sands tailings were dried under ambient conditions, and their residual solvent contents were measured by a purge and trap system followed by gas chromatography. The elemental compositions of the extraction tailings were measured to calculate bitumen recovery. Supernatants from the extraction tests were centrifuged to separate and measure the contents of fine solid particles. Except for limonene and isoprene, the tested solvents showed good bitumen recoveries of around 95%. The solvent drying rates and residual solvent contents in the extracted oil sands tailings correlated to solvent vapour pressure. The contents of fine solids in the extracted bitumen (supernatant) were below 2.9% for all solvents except n‐heptane‐rich ones. Based on these findings, cyclohexane is the best candidate solvent for bitumen extraction, with 94.4% bitumen recovery, 5 mg of residual solvent per kilogram of extraction tailings and 1.4 wt% fine solids in the recovered bitumen. © 2012 Canadian Society for Chemical Engineering  相似文献   
73.
The tumor suppressor p53 is involved in the recognition of DNA damage induced by radiation and chemicals. The effect of polycyclic hydrocarbons on p53 was investigated by treating MCF-7 cells with anti-benzo[a]pyrene-7,8-diol-9,10-epoxide (B[a]PDE), an ultimate carcinogenic metabolite of benzo[a]pyrene. Western blotting of lysates with antibody mAb1801 showed that B[a]PDE doses of 0.1 to 0.5 μM caused detectable increases in p53 protein. In cells treated with 0.3 μM B[a]PDE, p53 protein levels increased by 2 hours after treatment, reached a maximum between 8 and 24 hours and returned to control value by 120 hours after treatment. Levels of p21WAF1 protein increased by 8 hours after treatment, reached a maximum by 48 hours and returned to control value by 168 hours after treatment. B[a]PDE-DNA adducts were quantitated by [γ-33P]ATP postlabeling and separation on reverse-phase HPLC. Adduct levels dropped rapidly between 2 and 24 hrs after treatment (48 to 15 pmol/mg DNA), and subsequently decreased more slowly (12 pmol/mg DNA at 48 hrs to 3 at 168 hrs). By 96 hours after treatment, p53 protein levels were comparable to those from untreated controls, although a low level of B[a]PDE-DNA adducts remained. Cells treated with B[a]PDE also incorporated significantly less [3H]thymidine into DNA than did untreated cells for at least 24 hours after treatment. These results provide preliminary evidence that B[a]PDE-induced DNA damage is recognized by a p53-dependent signal transduction pathway and suggest that cell cycle arrest occurs during the repair of the majority of the B[a]PDE-DNA adducts.  相似文献   
74.
Brain metastases are a much-feared complication of cancer. The development of brain metastases requires a malignant cell to acquire characteristics that facilitate dissemination away from the primary site, entrance into the nervous system, and establishment in the brain. This review summarizes recent work focused on the molecular derangements leading to brain metastases and outlines areas in need of greater understanding.  相似文献   
75.
76.
Demand for biodiesel has increased due to being a more environmentally-friendly fuel. Cold weather operation of biodiesel is challenging due to fatty acid methyl ester (FAME) content in biodiesel. Saturated FAMEs crystallize at relatively high temperatures, increase the viscosity of biodiesel, and can clog fuel lines. Here, several factors altered crystallization temperature (CT) of FAMEs, including composition, shear rate, and cooling rate. The crystallization of pure and binary mixtures of methyl palmitate, methyl myristate, and methyl stearate were studied under shear flow and static conditions. Static phase CTs of pure methyl palmitate, methyl myristate, and methyl stearate were 26, 14, and 35°C, respectively. In binary mixtures, CTs were depressed up to 7°C, which agreed with freezing point depression theory. Increasing shear rate up to 100 s−1 decreased CT by 2°C compared to static conditions. Decreasing cooling rate from 1 to 0.1°C/min increased CT less than 2°C. Overall, FAME composition altered CT more than shear flow or cooling rate for pure and binary mixtures of three FAMEs.  相似文献   
77.
Wound healing (WH) proceeds through four distinct phases: hemostasis, inflammation, proliferation, and remodeling. Impaired WH may be the consequence of the alteration of one of these phases and represents a significant health and economic burden to millions of individuals. Thus, new therapeutic strategies are the topics of intense research worldwide. Although radiofrequency electromagnetic field (RF-EMF) has many medical applications in rehabilitation, pain associated with musculoskeletal disorders, and degenerative joint disorders, its impact on WH is not fully understood. The process of WH begins just after injury and continues during the inflammatory and proliferative phases. A thorough understanding of the mechanisms by which RF-EMF can improve WH is required before it can be used as a non-invasive, inexpensive, and easily self-applicable therapeutic strategy. Thus, the aim of this study is to explore the therapeutic potential of different exposure setups of RF-EMF to drive faster healing, evaluating the keratinocytes migration, cytokines, and matrix metalloproteinases (MMPs) expression. The results showed that RF-EMF treatment promotes keratinocytes’ migration and regulates the expression of genes involved in healing, such as MMPs, tissue inhibitors of metalloproteinases, and pro/anti-inflammatory cytokines, to improve WH.  相似文献   
78.
79.
The microstructural transition of aqueous 0.1 M cetylpyridinium chloride (CPC) in the combined presence of salt KBr and long chain alcohol (C9OH-C12OH) has been studied as a function of alcohol concentration, electrolyte concentration and temperature. The viscosity of the CPC/KBr micellar system showed a peaked behavior with alcohol concentration (C 0), due to alcohol induced structural transition, which was confirmed by dynamic light scattering (DLS) and rheological analysis. Besides C 0, the chain length of alcohol (n) was found to show a remarkable effect on the micellization behavior of CPC/KBr system. It was observed that the ability of alcohol to induce micelle growth diminishes with n, which was well supported by viscosity, rheology and DLS measurements. To examine the effect of the electrolyte on the micellar growth, the salt concentration was varied from 0.05 to 0.15 M and it was observed that with increase in [KBr], the peak position shifts towards lower C 0. The effect of temperature on the micellar system showed interesting phase behavior for CPC/KBr/Decanol. The system exhibited a closed solubility loop with an upper critical solution temperature (UCST) > the lower critical solution temperature (LCST), reminiscence of nicotine-water system. The role of surfactant head group on the structural evolution was revealed by comparing the present results with our previous report for similar micellar system, CTAB/KBr/long chain alcohol.  相似文献   
80.
Microneedles are small needle‐like structures that are almost invisible to the naked eye. They have an immense potential to serve as a valuable tool in many medical applications, such as painless vaccination. Microneedles work by breaking through the stratum corneum, the outermost barrier layer of the skin, and providing a direct path for drug delivery into the skin. A lot of research has been presented over the past two decades on the applications of microneedles, yet the fundamental mechanism of how they interact, pressure, and penetrate the skin in its native state is worth examining further. As such, a major difficulty with understanding the mechanism of microneedle–skin interaction is the lack of an artificial mechanical human skin model to use as a standardized substrate. In this research news, the development of an artificial mechanical skin model based on a thorough mechanical study of fresh human and porcine skin samples is presented. The artificial mechanical skin model can be used to study the mechanical interactions between microneedles and skin, but not diffusion of molecules across skin. This model can assist in improving the performance of microneedles by enhancing the reproducibility of microneedle depth insertions for optimal drug delivery and biosensing.

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