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Fabrication of Micro-Dimpled Surfaces through Micro Ball End Milling
Eldon Graham,Chaneel I. Park,Simon S. Park 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.
Industry and researchers have begun to shift their focus towards more sustainable and eco-friendly manufacturing processes in recent years. They have recognized the vital role of functional micro surfaces for a wide range of advanced applications to address this issue. By physically altering the surface structure of a material in micrometric scale, tribological, optical, fluidic properties and many other surface characteristics can be altered. Several researchers have reported that micro surface patterns can reduce friction between lubricated sliding surfaces, which in turn alleviate energy consumption and increase service life of components. Micro ball end milling is another viable technique for creating patterned surfaces, especially for metallic parts. By tilting the spindle and tool at an inclined angle, the spindle speed and feed rate can be adjusted so that the flutes of the cutter create periodic patterns in a workpiece surface. Machining is an efficient and versatile manufacturing technique, making the micro dimple machining technique an ideal method to fabricate dimpled surfaces. In this study, the fabricated surfaces are evaluated at a tribological level to illustrate their effectiveness at reducing friction. The development of efficient methods to produce micro patterns onto large surface areas can promote a sustainable future for a variety of novel products. The development of efficient surface pattern algorithms for generating different dimple geometries is also a focus; and, trends in cutting forces are identified by changing different machining parameters. Depth of cut and dimple shape, spacing and arrangement are crucial parameters, all of which factor into the performance of a functional surface. The results of this study strongly indicate micro dimple machining as an environmentally sustainable method of producing functional surfaces for advanced technological applications.
Rene, Eldon R,Bernat, Przemyslaw,Dlugo?ski, Jerzy,Veiga, Maria C,Kennes, Christian Humana Press 2012 Applied biochemistry and biotechnology Vol.168 No.6
<P>Biodegradation of styrene by Exophiala sp. was tested at different initial concentrations (19.3-170.6 mgl(-1)), pH (2.8-8.7), and temperatures (19.8-45.1 C), for 120 h according to a 2(3) full-factorial central composite design. The specific growth rate (SGR, per hour) and specific styrene utilization rate (SUR, milligrams of styrene per milligram of biomass per hour) values were used as the response variables for optimization purposes. The interactions between concentration and temperature (P=0.022), and pH and temperature (P=0.010) for SGR, and interactions between concentration and temperature (P=0.012) for SUR were found to be statistically significant. The optimal values for achieving high SGR (0.15 h(-1)) and SUR (0.3622 mg styrene mg(-1) biomass h(-1)) were calculated from the regression model equation. Those values are C(o)=89.1 mgl(-1), pH=5.4, and T=31.5 C for SGR and C(o)=69.2 mgl(-1), pH=5.5, and T=32.4 C for SUR. It was also observed that the Exophiala strain degrades styrene via phenylacetic acid, involving initial oxidation of the vinyl side chain. Besides, in the presence of styrene, changes in the fatty acids profile were also observed. It is hypothesized that an increasing amount of linoleic acid (18:2) may be involved in the protection of the fungus against toxic substrate.</P>
Samayita Chakraborty,Eldon R. Rene,Piet N. L. Lens 한국미생물학회 2019 The journal of microbiology Vol.57 No.9
The simultaneous removal of phenol and selenite from synthetic wastewater was investigated by adopting two different co-culturing techniques using the fungus Phanerochaete chrysosporium and the bacterium Delftia lacustris. Separately grown biomass of the fungus and the bacterium (suspended co-culture) was incubated with different concentrations of phenol (0–1,200 mg/L) and selenite (10 mg/L). The selenite ions were biologically reduced to extracellular Se(0) nanoparticles (3.58 nm diameter) with the simultaneous degradation of up to 800 mg/L of phenol. Upon growing the fungus and the bacterium together using an attached growth co-culture, the bacterium grew as a biofilm onto the fungus. The extracellularly produced Se(0) in the attached growth co-culture had a minimum diameter of 58.5 nm. This co-culture was able to degrade completely 50 mg/L phenol, but was completely inhibited at a phenol concentration of 200 mg/L.
Review : Epidemiology of Gallbladder Disease: Cholelithiasis and Cancer
( Laura M. Stinton ),( Eldon A. Shaffer ) The Editorial Office of Gut and Liver 2012 Gut and Liver Vol.6 No.2
Diseases of the gallbladder are common and costly. The best epidemiological screening method to accurately determine point prevalence of gallstone disease is ultrasonography. Many risk factors for cholesterol gallstone formation are not modifiable such as ethnic background, increasing age, female gender and family history or genetics. Conversely, the modifi able risks for cholesterol gallstones are obesity, rapid weight loss and a sedentary lifestyle. The rising epidemic of obesity and the metabolic syndrome predicts an escalation of cholesterol gallstone frequency. Risk factors for biliary sludge include pregnancy, drugs like ceftiaxone, octreotide and thiazide diuretics, and total parenteral nutrition or fasting. Diseases like cirrhosis, chronic hemolysis and ileal Crohn`s disease are risk factors for black pigment stones. Gallstone disease in childhood, once considered rare, has become increasingly recognized with similar risk factors as those in adults, particularly obesity. Gallbladder cancer is uncommon in developed countries. In the U.S., it accounts for only ~ 5,000 cases per year. Elsewhere, high incidence rates occur in North and South American Indians. Other than ethnicity and female gender, additional risk factors for gallbladder cancer include cholelithiasis, advancing age, chronic infl ammatory conditions affecting the gallbladder, congenital biliary abnormalities, and diagnostic confusion over gallbladder polyps. (Gut Liver 2012;6:172-187)