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排序方式: 共有229条查询结果,搜索用时 15 毫秒
51.
Paul M. Young Handoko Adi Tajel Patel Katherine Law Philippe Rogueda Daniela Traini 《Journal of aerosol science》2009,40(4):324-337
A fundamental study of the interactions between binary particulate formulations in HFA-based pressurised metered dose inhaler (pMDI) systems was undertaken. Differences in the surface energetics of lactose, mannitol and sibenadet hydrochloride were observed, which could be related to the degree of particle adhesion/cohesion, the sedimentation rate and the aerosolisation performance of formulations containing different mixtures of these components. In general, lactose was shown to be the most cohesive material and readily formed coarse aggregates with sibenadet hydrochloride which sedimented rapidly. This had the greatest effect on aerosolisation performance at high-lactose concentrations (and low-sibenadet hydrochloride concentrations), where heavily agglomerated particles were observed in collected samples of the emitted aerosol. A model, relating the adhesive and cohesive forces between the components in these systems has been proposed, which satisfactorily describes these phenomena. Furthermore, although the more energetic systems were shown to result in significantly decreased aerosol performance, the through-life performance was enhanced. 相似文献
52.
Riaz Ahmed Shaikh Kamel Adi Luigi Logrippo 《International Journal of Information Security》2017,16(1):91-113
Access control policies may contain anomalies such as incompleteness and inconsistency, which can result in security vulnerabilities. Detecting such anomalies in large sets of complex policies automatically is a difficult and challenging problem. In this paper, we propose a novel method for detecting inconsistency and incompleteness in access control policies with the help of data classification tools well known in data mining. Our proposed method consists of three phases: firstly, we perform parsing on the policy data set; this includes ordering of attributes and normalization of Boolean expressions. Secondly, we generate decision trees with the help of our proposed algorithm, which is a modification of the well-known C4.5 algorithm. Thirdly, we execute our proposed anomaly detection algorithm on the resulting decision trees. The results of the anomaly detection algorithm are presented to the policy administrator who will take remediation measures. In contrast to other known policy validation methods, our method provides means for handling incompleteness, continuous values and complex Boolean expressions. In order to demonstrate the efficiency of our method in discovering inconsistencies, incompleteness and redundancies in access control policies, we also provide a proof-of-concept implementation. 相似文献
53.
Synthesis of short-channeled amino-functionalized SBA-15 and its beneficial applications in base-catalyzed reactions 总被引:1,自引:0,他引:1
Amino-functionalized-SBA-15 catalysts with nanostructured hexagonal platelet morphologies were synthesized directly by using microwave synthesis from the hydrolysis and co-condensation of aminopropyltriethoxysilane (APTES) and sodium metasilicate under a strong acidic condition with the Pluronic P123 triblock copolymer as a structure-directing agent. The amino-functionalized-SBA-15 catalysts were proven by SEM and TEM techniques to have very short channels in the range of 200–300 nm perpendicular to the hexagonal platelet morphologies. These short-channeled catalysts were proven to be effective heterogeneous catalysts in liquid-phase reactions such as Knoevenagel and Claisen-Schmidt condensations as well as in Henry reaction. They exhibited greatly improved catalytic activities over the typical fibrous type SBA-15 catalyst having long channels. Obviously, the easy diffusion and rapid mass transfer of substrate into the short channel mesopores played important roles in the significant improvement in the catalytic activities. 相似文献
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Pulak R. Manna Sabarish Ramachandran Jangampalli Adi Pradeepkiran Deborah Molehin Isabel Castro-Piedras Kevin Pruitt Vadivel Ganapathy P. Hemachandra Reddy 《International journal of molecular sciences》2023,24(1)
Breast cancer (BC) is primarily triggered by estrogens, especially 17β-estradiol (E2), which are synthesized by the aromatase enzyme. While all steroid hormones are derived from cholesterol, the rate-limiting step in steroid biosynthesis is mediated by the steroidogenic acute regulatory (StAR) protein. Herein, we demonstrate that StAR mRNA expression was aberrantly high in human hormone-dependent BC (MCF7, MDA-MB-361, and T-47D), modest in hormone-independent triple negative BC (TNBC; MDA-MB-468, BT-549, and MDA-MB-231), and had little to none in non-cancerous mammary epithelial (HMEC, MCF10A, and MCF12F) cells. In contrast, these cell lines showed abundant expression of aromatase (CYP19A1) mRNA. Immunofluorescence displayed qualitatively similar patterns of both StAR and aromatase expression in various breast cells. Additionally, three different transgenic (Tg) mouse models of spontaneous breast tumors, i.e., MMTV-Neu, MMTV-HRAS, and MMTV-PyMT, demonstrated markedly higher expression of StAR mRNA/protein in breast tumors than in normal mammary tissue. While breast tumors in these mouse models exhibited higher expression of ERα, ERβ, and PR mRNAs, their levels were undetected in TNBC tumors. Accumulation of E2 in plasma and breast tissues, from MMTV-PyMT and non-cancerous Tg mice, correlated with StAR, but not with aromatase, signifying the importance of StAR in governing E2 biosynthesis in mammary tissue. Treatment with a variety of histone deacetylase inhibitors (HDACIs) in primary cultures of enriched breast tumor epithelial cells, from MMTV-PyMT mice, resulted in suppression of StAR and E2 levels. Importantly, inhibition of StAR, concomitant with E2 synthesis, by various HDACIs, at clinical and preclinical doses, in MCF7 cells, indicated therapeutic relevance of StAR in hormone-dependent BCs. These findings provide insights into the molecular events underlying the differential expression of StAR in human and mouse cancerous and non-cancerous breast cells/tissues, highlighting StAR could serve not only as a novel diagnostic maker but also as a therapeutic target for the most prevalent hormone-sensitive BCs. 相似文献
56.
Alexey A. Lipengolts Yulia A. Finogenova Vsevolod A. Skribitsky Kristina E. Shpakova Adi Anaki Menachem Motiei Alevtina S. Semkina Maxim A. Abakumov Anna V. Smirnova Elena Y. Grigorieva Rachela Popovtzer 《International journal of molecular sciences》2023,24(1)
Gold-containing nanoparticles are proven to be an effective radiosensitizer in the radiotherapy of tumors. Reliable imaging of nanoparticles in a tumor and surrounding normal tissues is crucial both for diagnostics and for nanoparticle application as radiosensitizers. The Fe3O4 core was introduced into gold nanoparticles to form a core/shell structure suitable for MRI imaging. The aim of this study was to assess the in vivo bimodal CT and MRI enhancement ability of novel core/shell Fe3O4@Au theranostic nanoparticles. Core/shell Fe3O4@Au nanoparticles were synthesized and coated with PEG and glucose. C57Bl/6 mice bearing Ca755 mammary adenocarcinoma tumors received intravenous injections of the nanoparticles. CT and MRI were performed at several timepoints between 5 and 102 min, and on day 17 post-injection. Core/shell Fe3O4@Au nanoparticles provided significant enhancement of the tumor and tumor blood vessels. Nanoparticles also accumulated in the liver and spleen and were retained in these organs for 17 days. Mice did not show any signs of toxicity over the study duration. These results indicate that theranostic bimodal Fe3O4@Au nanoparticles are non-toxic and serve as effective contrast agents both for CT and MRI diagnostics. These nanoparticles have potential for future biomedical applications in cancer diagnostics and beyond. 相似文献
57.
S. Lakshmi Narayana S. Adi Narayana Reddy Y. Subbarao Hwang Inseong A. Varada Reddy 《Food chemistry》2010
A simple, rapid, sensitive and inexpensive method has been developed for the determination of trace amounts of chromium(VI) using 3,4-dihydroxybenzaldehydeisonicotinoylhydrazone (3,4-DHBINH). The metal ion gives a yellow coloured complex with 3,4-DHBINH in acetate buffer of pH 5.5 with 1:1 (metal:ligand) composition. The complex shows a maximum absorption at 400 nm. Beer’s law is obeyed in the range 0.5–7.7 ppm of Cr(VI). The molar absorptivity, Sandell’s sensitivity and detection limit were found to be 1.35 × 104 L mol−1 cm−1, 0.0075 μg cm−2 and 0.0045 μg mL−1, respectively. The correlation co-efficient and regression co-efficient of the Cr(VI)–3,4-DHBINH complex were 0.99 and 0.12, respectively. Major cations and anions did not show any interference. The developed method has been successfully applied for the analysis of Cr(VI) in food samples (leafy vegetables), comparing the results simultaneously with those obtained using an Atomic Absorption Spectrophotometer, whereby the validity of the method has been tested. 相似文献
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We show that the electrode/molecule chemical bond does not change the tunneling barrier for charge transport through alkyl chain monolayers sandwiched between Si and Hg electrodes. This observation can be understood if the interfacial bond mainly governs the monolayer's structure, while the electronic states due to molecule-electrode bonding do not contribute significantly to tunneling. Yet, the nature of the bond affects the Schottky barrier inside the semiconductor due to changes in the interface dipole. 相似文献