2,919 research outputs found
Degradation of Addition Polymers by Ultrasonic Waves and the Role of Cavitation
Abstract Not Provided
Inclusion properties of certain subclasses of analytic functions defined by generalized Salagean operator
Let denote the class of analytic functions with the normalization in the open unit disc U=\{z:\left\vert z\right\vert <1\}. Set and define in terms of the Hadamard product f_{\lambda }^{n}(z)\ast f_{\lambda ,\mu }^{n}=\frac{z}{(1-z)^{\mu }}\quad (\mu >0;\ z\in U). In this paper, we introduce several subclasses of analytic functions defined by means of the operator , given by I_{\lambda ,\mu }^{n}f(z)=f_{\lambda ,\mu }^{n}(z)\ast f(z)\quad (f\in A;\ n\in N_{0;}\ \lambda \geq 0;\ \mu >0). Inclusion properties of these classes and the classes involving the generalized Libera integral operator are also considered
Collective Mechanochemical Growth of Carbon Nanotubes.
Hierarchically ordered carbon nanotubes (CNTs) are promising for integration in high-performance structural composites, electrical interconnects, thermal interfaces, and filtration membranes. These and other applications require CNTs that are monodisperse, well aligned, and densely packed. Moreover, because more than 1 billion CNTs per square centimeter grow simultaneously in a typical chemical vapor deposition (CVD) process, understanding the collective chemical and mechanical effects of growth is key to engineering the properties of CNT-based materials. This dissertation presents tailored synthesis processes, characterization techniques, and mathematical models that enable improved control of the morphology of as-grown CNT “forests.”
First, a comprehensive characterization methodology, combining synchrotron X-ray scattering and attenuation with real-time height kinetics, enabled mapping the spatiotemporal evolution of CNT diameter distribution, alignment and density. By this method, the forest mass kinetics were measured and found to follow the S-shaped Gompertz curve of population growth. Dividing a forest into subpopulations revealed size-dependent activation-deactivation competition. Additionally, in situ transmission electron microscopy (TEM) showed that the kinetics of CNT nucleation are S-shaped. Based on these findings, a collective growth model is proposed, wherein randomly oriented CNTs first nucleate then self-organize and lift-off during a crowding stage, followed by a density decay stage until self-termination when the density drops below the self-supporting threshold.
Next, further X-ray data analysis enabled modeling the mechanics of entangled CNTs and proved that mechanical coupling is not only responsible for the self-organization into the aligned morphology, but is also an important limiting mechanism as significant forces ensue from diameter-dependent CNT growth rates. A custom-built CVD system was used for mechanical manipulation of growing CNTs, leading to insights that external forces modulate the reaction kinetics. Last, a mathematical model describing the synergetic chemical coupling among growing CNT micropillars predicted height variations, and enables the design of CNT catalyst patterns for improved uniformity.
The insights in this dissertation contribute to the fundamental understanding of self-organized CNT growth, enabling improved manufacturing and metrology. The models and techniques for studying population behavior of nanofilaments may also be applied to other systems, such as inorganic nanotubes, nanowires, and biofilaments.PhDMechanical EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/107179/1/mbedewy_1.pd
Detection and Identification of Helicobacter pullorum in Poultry Species in Upper Egypt
This work aimed to detect, identify and study the epidemiology of Helicobacter pullorum in avian species in Upper Egypt. A total of 1800 samples, including cloacal swabs, cecal swabs and livers were collected from chickens, turkeys and ducks in five different governorates in Upper Egypt. Using conventional phenotypic methods for isolation and identification, Helicobacter pullorum could be identified only from chickens with percentage 39.33% and no presence of the organism in turkeys and ducks. Sixteen randomly selected phenotypically identified Helicobacter pullorum isolates were confirmed using PCR assay based on 16S rRNA gene. In conclusion, conventional phenotypic methods for detection and differentiation of Helicobacter pullorum are often hampered by many limitations, while molecular methods, and PCR, in particular, have marked an important step forward in bacterial diagnostics and can provide a sensitive and rapid alternative method for detection and identification and highlights the potential of PCR technology in routine detection and identification of pathogens
A Novel Approach in Pigment Printing Using Nano-keratin Based Binder
This study is devoted to preparation and characterization of nano-keratin based binder (NKBB) from cheap renewable natural resources, namely coarse Egyptian wool or feather. The prepared NKBB is utilized as a biodegradable, environment-friendly and relatively cheap binder in textile pigment printing of polyester, pure polyacrylic, viscose, polyester/viscose, and polyester/acrylic fabrics. Different concentrations of the prepared NKBB as well as its mixture with commercially produced one are used in the pigment printing paste. The colour strength of the printed fabrics as well as their fastness properties to light, washing, and perspiration are evaluated. The effect of the used binder on the bending stiffness of the printed fabrics is also assessed. Results show that the NKBB gives almost the same colour strength and fastness properties as the commercial binder with improved stiffness of the printed samples in relation to that printed with commercial one
A study on certain class of harmonic functions of complex order associated with convolution
In this paper, we introduce a new class of harmonic functions of complex order associated with convolution. We also derive the coefficient inequality, distortion theorem, extreme points, convolution conditions and convex combination for this class
Differentiation of Infectious Bursal Disease Virus (IBDV) Strains in Experimentally Infected Chickens
Infectious bursal disease (IBD) is an acute, highly contagious, and immunosuppressive avian disease caused by IBD virus (IBDV). Differentiation of IBDV strains is crucial for effective vaccination programs and epidemiological investigations. In this study, a combination of clinical, histopathological examinations, immunohistochemistry and indirect immunofluorescence techniques were used to differentiate different IBDV strains. Sixty three weeks old chickens were divided randomly into five equal groups. Chickens of four groups were inoculated orally with different strains of IBDV. Chickens of the fifth group were kept as a control. Three chickens per group were euthanized at 3, 7, 14, 21 days post-inoculation (dpi). Euthanized chickens subjected to autopsy and tissue samples were collected in 10% neutral-buffered formalin for histopathology, immunohistochimestry and immunoflrourescence. The results revealed that clinical examination and histopathology cannot be used alone for differentiation of IBDV strains, while immunohistochemical and immunofluorescence techniques are reliable tools for differentiation of IBDV strains
Quantitative Soil Descriptions for Ecoregions of the United States
Researchers have defined and mapped ecological regions of the United States based on similar patterns of ecosystems such as deserts, forests, and croplands. These studies are useful in regional research, monitoring, and environmental management because data can be more readily extrapolated within the same ecoregion and to regions with similar characteristics. The description of ecoregions is largely holistic and qualitative. Conversely, quantitative information for soil are abundant and soil is an important ecosystem component related to many ecoregion properties. We used the nationwide State Soil Geographic database(STATSGO) to describe the soils of 84 Level III ecoregions in the United States. Among the 24 soil characteristics studied were texture, rock fragments, available water capacity, bulk density, and organic matter content. For each ecoregion we developed ranks to describe (i) its similarity to the U.S. average soil characteristics, (ii) the accuracy of predicting those characteristics, (iii) how well the soil map unit boundaries fit within ecoregion boundaries, (iv) the spatial relationship of soils across neighboring ecoregion boundaries, and (v) the homogeneity of texture-rock patterns. We present a national map of soil texture and rock fragments and five soil ranks for each ecoregion, and examine relationship between soils and other ecological components for selected ecoregions. Because soils relate to other ecosystem components such as vegetation, geology, and land use, the soil ranks complement and enrich the qualitative ecoregion descriptions. Similar analyses of physical or biological components of ecoregions will expand the understanding of the ecosystem patterns
Subclass of harmonic univalent functions defined by Dziok-Srivastava operator
In this paper we introduce a new class of harmonic univalent functions defined by the Dziok-Srivastava operator. Coefficient estimates, extreme points, distortion bounds and convex combination for functions belonging to this class are obtained and also for a class preserving the integral operator
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