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排序方式: 共有211条查询结果,搜索用时 980 毫秒
1.
A Nandakumar N Anantha L Appaji K Swamy G Mukherjee T Venugopal S Reddy M Dhar 《Canadian Metallurgical Quarterly》1996,7(4):405-410
While fairly complete and reliable incident data on childhood cancers are available from the registries in India, mortality and survival information is not. Information concerning the latter was obtained by the Bangalore cancer registry through active follow-up involving visits to homes of patients. Between 1982 and 1989, 617 cases of cancers in childhood were registered, giving an age-standardized incidence rate of 84.8 and 48.4 per million in male and female children, respectively. Active follow-up provided mortality/survival information in 532 or 86.2 percent of these cases. Overall, observed five-year survival was 36.8 percent (both genders combined) with a relative survival of 37.5 percent when childhood mortality in the general population was taken into account. The five-year relative survival was best for thyroid carcinoma (100 percent) followed by Hodgkin's disease (73 percent) and retinoblastoma (72.9 percent). Survival was comparatively low, being 9.9 percent in acute nonlymphatic leukemia and less than 20 percent in rhabdomyosarcoma and the category grouped as 'other malignant neoplasms.' Survival in Hodgkin's disease was influenced by clinical stage at presentation, but was not statistically significant possibly due to small numbers. 相似文献
2.
Kwang‐Pill Lee Anantha Iyengar Gopalan See‐Hee Lee Ali Md Showkat Young Chang Nho 《应用聚合物科学杂志》2006,102(4):3912-3918
Conducting polydiphenylamine was used to encapsulate silica nanoparticles through the oxidative polymerization of diphenylamine in the presence of ultrasonic irradiation. The polymerization was performed in the presence of sodium lauryl sulfate as a surfactant. Experiments performed in the absence of ultrasound clearly demonstrated that the application of ultrasonication played multiple roles in the preparation of a composite of polydiphenylamine with silica nanoparticles. Ultrasonication dispersed the silica nanoparticles, converted sodium lauryl sulfate to lauryl alcohol, and augmented the dispersion of the silica‐nanoparticle/polydiphenylamine composite in an organic medium. Silica‐nanoparticle/polydiphenylamine composites were also prepared in the absence of ultrasound and/or sodium lauryl sulfate. The silica‐nanoparticle/polydiphenylamine composites were characterized with Fourier trans form infrared spectroscopy, ultraviolet–visible/near‐infrared spectroscopy, and thermogravimetric analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 3912–3918, 2006 相似文献
3.
Nanocomposites of iron oxide (Fe3O4) with a sulfonated polyaniline, poly(aniline‐co‐aminonaphthalenesulfonic acid) [SPAN(ANSA)], were synthesized through chemical oxidative copolymerization of aniline and 5‐amino‐2‐naphthalenesulfonic acid/1‐amino‐5‐naphthalenesulfonic acid in the presence of Fe3O4 nanoparticles. The nanocomposites [Fe3O4/SPAN(ANSA)‐NCs] were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X‐ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, elemental analysis, UV–visible spectroscopy, thermogravimetric analysis (TGA), superconductor quantum interference device (SQUID), and electrical conductivity measurements. The TEM images reveal that nanocrystalline Fe3O4 particles were homogeneously incorporated within the polymer matrix with the sizes in the range of 10–15 nm. XRD pattern reveals that pure Fe3O4 particles are having spinel structure, and nanocomposites are more crystalline in comparison to pristine polymers. Differential thermogravimetric (DTG) curves obtained through TGA informs that polymer chains in the composites have better thermal stability than that of the pristine copolymers. FTIR spectra provide information on the structure of the composites. The conductivity of the nanocomposites (~ 0.5 S cm?1) is higher than that of pristine PANI (~ 10?3 S cm?1). The charge transport behavior of the composites is explained through temperature difference of conductivity. The temperature dependence of conductivity fits with the quasi‐1D variable range hopping (quasi‐1D VRH) model. SQUID analysis reveals that the composites show ferromagnetic behavior at room temperature. The maximum saturation magnetization of the composite is 9.7 emu g?1. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 相似文献
4.
Ali Md Showkat Kwang‐Pill Lee Anantha Iyengar Gopalan Sang‐Ho Kim Seong‐Ho Choi Sang‐Ho Sohn 《应用聚合物科学杂志》2006,101(6):3721-3729
Composites based on poly(diphenyl amine) (PDPA) and multiwall carbon nanotubes (MWNTs) were prepared by chemical oxidative polymerization through two different approaches: in situ polymerization and intimate mixing. In in situ polymerization, DPA was polymerized in the presence of dispersed MWNTs in sulfuric acid medium for different molar composition ratios of MWNT and DPA. Intimate mixing of synthesized PDPA with MWNT was also used for the preparation of PDPA/MWNT composites. Transmission electron microscopy revealed that the diameter of the tubular structure for the composite was 10–20 nm higher than the diameter of pure MWNT. Scanning electron microscopy provided evidence for the differences in the morphology between the MWNTs and the composites. Raman and Fourier transform IR (FTIR) spectroscopy, thermogravimetric analysis, X‐ray diffraction, and UV–visible spectroscopy were used to characterize the composites and reveal the differences in the molecular level interactions between the components in the composites. The Raman and FTIR spectral results revealed doping‐type molecular interactions and coordinate covalent‐type interactions between MWNT and PDPA in the composite prepared by in situ polymerization and intimate mixing, respectively. The backbone structure of PDPA in the composite decomposed at a higher temperature (>340°C) than the pristine PDPA (~300°C). This behavior also favored the molecular level interactions between MWNT and PDPA in the composite. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3721–3729, 2006 相似文献
5.
Traditional intumescent coatings are widely used as passive fire-protective coatings for steel structures as they are capable of expanding in the range of 20–50 times the original thickness thereby providing excellent insulation. However, the fragile nature of such residue and susceptibility to thermo-oxidation given their carbonaceous nature are key problematic issues. The concept of in situ ceramization is explored in this work as a means to form inorganic cohesive char with improved rigidity and thermo-oxidative stability. Coating samples were prepared by incorporating ammonium polyphosphate, talc, Mg(OH)2, and polydimethylsiloxane as additives into acrylic resin at different weight fractions. Thermal analysis and x-ray diffraction have confirmed the reactions between the additives to form various crystalline magnesium phosphate phases, and to a small extent, silicon phosphate, thereby ensuring the thermo-oxidative stability of the residue. This is reiterated by the fire performance tests (by exposing the coatings to a temperature profile in a furnace similar to ISO 834 fire curve). Despite the advantages of rigid char and its thermo-oxidative stability as a result of formation of inorganic phosphates, the lack of swelling has resulted in relatively poor insulation capabilities of the char, and subsequently, compromised the fire protection times (that are in the range of 45–55 min). However, pyrolysis flow combustion calorimeter results of the coatings are promising and have shown a significant drop of up to 70% in the peak of heat release rate values as compared to neat resin. 相似文献
6.
7.
Anantha Kumar Duraiappah 《Computational Economics》2001,18(2):193-215
In order to analyze, understand and prescribe natural resourcemanagement strategies, the decision making framework should ideallycapture the dynamics of inter-dependency between the economic andecological systems in an integrated manner. However, by including twocomplex systems within a single integrated framework makes many of thepresent analytical tools redundant. Computational models on the otherhand are ideally suited to meet this challenge. The size and complexityof models solved through numerical techniques have increasedexponentially over the last decade. This is especially true fornon-linear optimization models. However, although the science of solvingnon-linear models has improved significantly, the solving of thesemodels is still an art. In this paper, we look at the criticalparameters that a modeler needs to be aware of when developingintegrated economic-ecology models and some `tricks' to solve them withthe minimum of effort through the use of the optimization software GAMS(General Algebraic Modeling System). 相似文献
8.
Full instrumental rationality and perfect institutions are two cornerstoneassumptions underlying neoclassical models. However, in the real world, thesetwo assumptions never hold, especially not in developing countries. In thispaper, we develop a game theoretical model to investigate if relaxations inthe full instrumental rationality and perfect institutions premise can explainthe conflicts that have been occurring between the various principals in theNarok district in Kenya with regard to land tenure and use. 相似文献
9.
Aravind Dasari Zhong-Zhen Yu Mingshu Yang Qing-Xin Zhang Xiao-Lin Xie Yiu-Wing Mai 《Composites Science and Technology》2006,66(16):3097-3114
The primary aim of this paper is to provide an insight on the effect of the location of organoclay on the micro- and nano-scale deformation processes in melt-compounded nylon 66/organoclay/SEBS-g-MA ternary nanocomposites prepared by different blending sequences. In addition, the deformation processes of the ternary nanocomposites were compared to the binary nanocomposites (nylon 66/organoclay and nylon 66/SEBS-g-MA) and neat nylon 66. The incorporation of SEBS-g-MA particles toughened nylon 66 markedly; but the flexural modulus and strength were both reduced. Conversely, the use of organoclay increased the modulus but decreased the fracture toughness of nylon 66. Nylon 66/SEBS-g-MA/organoclay ternary nanocomposites exhibited balanced elastic stiffness and toughness. Stress-whitening studies of the fracture surfaces in terms of gray level were also performed and an attempt was made to correlate the optical reflectivity characteristics with fracture toughness. It was concluded that the capability of SEBS-g-MA particles to cavitate was decreased by the presence of organoclay in the SEBS-g-MA phase, resulting in reduced toughening efficiency. The best micro-structure for toughness and other mechanical properties is thus to maximize the amount of exfoliated organoclay in the nylon 66 matrix rather than to have it embedded in the finely dispersed SEBS-g-MA particles. 相似文献
10.
Brian A. Jalaian Xu Yuan Yi Shi Y. Thomas Hou Wenjing Lou Scott F. Midkiff Venkat Dasari 《Wireless Networks》2018,24(7):2357-2374
Recent advances in MIMO degree-of-freedom (DoF) models allowed MIMO research to penetrate the networking community. Independent from MIMO, successive interference cancellation (SIC) is a powerful physical layer technique used in multi-user detection. Based on the understanding of the strengths and weaknesses of MIMO DoF and SIC, we propose to have DoF-based interference cancellation (IC) and SIC help each other so that (i) precious DoF resources can be conserved through the use of SIC and (ii) the stringent SINR threshold criteria can be met through the use of DoF-based IC. In this paper, we develop the necessary mathematical models to realize the two ideas in a multi-hop wireless network. Together with scheduling and routing constraints, we develop a cross-layer optimization framework with joint DoF IC and SIC. By applying the framework on a throughput maximization problem, we find that SIC and DoF IC can indeed work in harmony and achieve the two ideas that we propose. 相似文献