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Bionanotechnology and Cellular Biomaterials
Published in Anil Kumar Anal, Bionanotechnology, 2018
Cell is the structural unit of all living organisms. The term cell (Greek, kytos, cell; Latin, cella, hollow space) was coined in 1665 ad by Robert Hooke, first person to observe the cells in a cork under the primitive microscope. Two German scientists, Schleiden and Schwann, later in 1839 ad outlined the basic features of the cell theory, which describes cell as the basic unit of life. Cell theory has two main components, that is, living things are composed of cells and all cells arise from preexisting cells. Cells vary greatly with respect to shape, for instance, amoebae are irregular in shape, whereas bacteria may exist in rod, spiral, or comma shape; in multicellular organisms, cell shape varies with functions as shown in Figure 1.2. Cell size differs with species; smallest cell (0.2–0.5 µm) found as virus, whereas the largest cell is ostrich egg (6 in. with shell and 3 in. without shell). Cell number varies from single cell in unicellular organism to 60,000 billion cells in adult human (Gupta 2008).
Experimental studies on reflective finishing of aluminum sheet by CNC abrasive lapping
Published in Materials and Manufacturing Processes, 2023
Numerous researchers have looked into fixed abrasive lapping systems due to the efficient machining, affordable price, and consistent precision that these systems offer. MMR and surface roughness theoretical analysis and simulation were introduced as new technologies, together with a fixed abrasive technology. The rate of removal increased in a manner that was not linearly proportional to the abrasive diameter. The projected outcomes and the elimination rate that was experimentally determined are very different.[16] A mathematical model was constructed on to enhance the tool influence function, use Preston Law. This was done using altering the number of fixed abrasive diamond pellets, the aperture, and the position. Dong’s model does not take into account the lapped tool.[17] They constructed a model based on the unit cell theory to estimate the impact of the pad surface topography of the machining tool on production. Cracks, scratches, micro cracks, and residual stress can all be caused by lapping fragile materials. This type of damage is referred to as surface and subsurface damage.[18,19] While on lapping surfaces, rolling abrasives cause micro cracks in addition to scratches.[20] As a result, a significant amount of research has been conducted on the sub surface damage lapping process methods and parameters.[21] Conventional fixed abrasive lapping technology, which polishes planar optical surfaces, has been the primary focus of the majority of these experiments.
Influence of the number of carded non-woven layers on mechanical and acoustic performance
Published in The Journal of The Textile Institute, 2023
Eduardo Volkart da Rosa, Fernanda Steffens
Another important factor that may have influenced the tensile strength (MD and CD) in the non-woven fabrics produced by using a horizontal crosslapper is the fiber deposition angle formed between the web deposition speed (MD) and the speed of the web exit of the crosslapper (CD), which is referred to as the α angle, as seen in Figure 8. The greater the α angle, the lower the MD:CD ratio (Hearle & Stevenson, 1963), and, according to the author, the α angle may be measured following Equation (5), where Voutput is the web output velocity and Vinput is web input velocity. Thus, the following angles were identified for the samples with 24, 40, and 58 layers, respectively: 1.49, 0.89, and 0.61°. The values are coherent when observing the non-woven fabric production speeds (Table 1), where the material with the fewest layers shows the highest speed. This is because as the number of layers increases, the production speed decreases along with the α angle. Thus, the unit cell theory and the determination of the α angle may influence the results shown for tensile strength in non-wovens.
Effect of basal reinforcement on sinking and deformation of rubble mounds on a soft seabed
Published in International Journal of Geotechnical Engineering, 2022
Hamed Ghazi, Hadi Shahir, Abbas Ghalandarzadeh
Rubble loss due to rock particle penetration and immediate settlement of the seabed related to rock support of a pipeline in deep water was studied by De Vries et al. (2009), Visser and van der Meer (2008) and Beemsterboer (2013). They used an impulse balance relation to model the penetration of individual rocks. The impulse relation considered the forces acting on the rock, such as gravity, buoyancy, drag and bearing capacity. The total penetration was calculated by integration of a decrease in the velocity during penetration. Ghazi, Shahir, and Haghparast (2018) presented an analytical solution for rock particle penetration into soft clay. The main parameters were rock size and density, overburden pressure at the surface of the seabed, undrained shear strength of the clayey bed, and impact velocity of the rock. However, this equation was insufficient to calculate the total volume lost in the course of rubble-mound breakwater construction on a soft seabed. The separation of the rubble and soft marine deposits using nonwoven geotextiles, geogrids and sand mattresses have been studied using unit cell theory (Tatfi and Fakher 2001; Mobarrez, Tatfi, and Fakher 2004; Mobarrez and Fakher 2005). Kahlström, Frossard, and Mattsson (2015) also compared the predicted settlement of rock foundations installed on a seabed using finite element simulation and field measurements.