Movement of Myoblast Flowing Through Electric Field Perpendicular to Flow Channel

The sorting technology with little invasion to cells would be applied to regenerative medicine and diagnosis. In this study, dielectrophoresis is focused on. The dielectrophoretic effect on the flowing myoblasts was maximized by adjusting several parameters: the shape of the electrodes, the amplitude and frequency of the alternating current. The suspension of C2C12 (mouse myoblast cell line) was injected into the channel, and the movement of each flowing cell was analyzed at the microscopic movie image. A pair of titanium-coated (200 nm thick) asymmetric surface electrodes (a triangular electrode with a tip angle of 0.35 rad and a rectangular reference electrode with a flat edge) was manufactured by photolithography technique. With the alternating square cyclic wave at the frequency of 3 MHz and the amplitude of current of ± 7.5 mA, 70 μm movement along the electric field (perpendicular to the main flow direction) of the cell was obtained. The movement along the electric field is governed by several parameters of the cell: the diameter, the deformation ratio, and the direction of the major axis. The method can be applied to cell sorting.

Dual modulation of topological edge states from two-dimensional photonic crystals with lattice shrink

The current topological edge states lack dynamical modulation and the intense field localization effect. To solve these problems, we construct a topological edge state structure based on two-dimensional photonic crystals with lattice shrink. Through the optimization of structure parameters, a nearly flat edge state dispersion curve occurs in a wide bandgap. The topological edge states with intense field localization take on some unique properties such that the transport directions can be controlled by both the source spin and the source position. The transport modes can be dynamically switched between the two opposite unidirectional channels just through moving the source position.

Micro Defects on Diamond Tool Cutting Edge Affecting the Ductile-Mode Machining of KDP Crystal

As a soft-brittle material, the machined surface quality of potassium dihydrogen phosphate (KDP) crystal is heavily affected by the edge quality of the diamond cutting tool. However, nanoscale micro defects inevitably occur on the freshly sharpened tool edge, and the machining mechanism for KDP crystal remains unclear. Therefore, in this work, three types of tool-edge micro defects are classified according to their cross-sections, including the blunt-edge, crescent-edge, and flat-edge micro defects. Moreover, the smoothed particle hydrodynamics (SPH) method is employed to reveal the material removal mechanism of KDP crystal with consideration of different tool-edge micro defects, and the flat-edge micro defects are subdivided into flat edge A (similar to flank wear) and flat edge B (similar to chamfered edge) on the basis of their effects in machining. The simulation results indicate that the surfaces machined by crescent edge and flat edge A are unsmooth with large-size defects due to the disappearance of hydrostatic pressure beneath the cutting edge. As for the blunt edge and flat edge B, the machined surfaces are smooth with a favorable increment of hydrostatic pressure for processing brittle materials, which indicates that a solution to eliminate the tool-edge micro defects is necessary, e.g., the passivation method. For keeping the cutting edge as sharp as possible in removing the tool-edge micro defects completely by passivation, the effect of tool shank depression angles on the geometries of the passivated cutting edge is investigated, and a high-quality cutting edge with a micro chamfered edge is obtained after passivation at a depression angle of 60° and re-sharpening of the rake face. Finally, the tool cutting performance after passivation is validated through fly-cutting experiments of KDP crystal. The chamfered edge can produce the best defect-free surface with the minimum surface roughness.

Biodiversity of Enterobacteriaceae on masin (fermented sauce) from Sumbawa, West Nusa Tenggara, Indonesia

Manguntungi B, Saputri DS, Afgani CA, Mustopa AZ, Fatimah, Kusmiran A. 2020. Biodiversity of Enterobacteriaceae on masin (fermented sauce) from Sumbawa, West Nusa Tenggara, Indonesia. Biodiversitas 21: 1001-1006. Masin is fermented sauce originating from Sumbawa, West Nusa Tenggara which is made from raw shrimp with the addition of tamarind, salt, and fingerroot (Boesenbergia pandurata) flower. The study aimed to determine the biodiversity of pathogenic bacteria, especially Enterobacteriaceae family in Masin. The methods used in this study were isolation of bacteria using MRS media with modified NaCl concentration (1-12%) and molecular identification by using PCR-RAPD (randomly amplified polymorphic DNA) analysis and 16S ribosomal RNA-based sequencing analysis. The characteristics of bacteria that were successfully isolated on media with various concentrations of salt were round, milky white, and formed a flat edge with convex elevation in each colony. The highest bacterial population was 29.65 x 106 CFU/g in MRS + NaCl 7% treatment. From 48 selected isolates that morphologically close to Enterobacteriaceae family, 5 isolates were chosen for sequencing analysis. Based on the phylogenetic analyses, isolate 01 had a close kinship with Leclercia adecarboxylata, isolate 11 had a close kinship with Citrobacter freundii, isolate 33 had a close kinship with Enterobacter cloacae, isolate 40 had a close kinship with Pantoea agglomerans and isolate 46 had a close kinship with Enterobacter ludwigii.

MORPHOLOGICAL CHARACTERISTICS OF NEPENTHES IN PEAT SWAMP AREA OF TULUNG SELAPAN, SOUTH SUMATERA

This study is aimed to recognise the morphological characteristics of Nepenthes mirabilis and Nepenthes gracilis in peat swamp area including stem, leaf, tendril, pitcher, flower, fruit, and seed. This study has been conducted in January until April 2018, located in Petaling Village Tulung Selapan Sub-District, Ogan Komering Ilir, South Sumatera. This study uses an exploratory method and the the observation sample using the method of random plot is chosen by purposive sampling. Parameters observed morphological characteristics of Nepenthes include stems, leaves, tendrils, pitcher, flower, adn fruit, as well as measurement of environmental factors. Based on the study, the researcher obtained two types of Nepenthes which are Nepenthes mirabilis and Nepenthes gracilis in peat swamp area of Petaling Village Tulung Selapan Sub-District, Ogan Komering Ilir. Nepenthes mirabilis has a teres stem, leaves that in the form of oblong to lanceolate, has a petiolate, the edge of the leaves is flat covered by smoothy hair, thick peristome in size of 0,4-0,5 cm. Meanwhile stem Nepenthes gracilis has triangular stem, leaves in formed of lanceolate, sessile, flat edge of leaves, thin peristome in size of 0,1-0,2 cm. The pitcher shape of Nepenthes mirabilis and Nepenthes gracilis are cylindrical, infundibulate, and waist. The flower of Nepenthes mirabilis and Nepenthes gracilis are compound in type of raceme inflorescences. The fruit is formed as capsula, has four lobed, and contains numerous seeds. The seed is spindle-like and white colored.

Analysis of a Flanged and Dished Head Assembly Used in a Horizontal Storage Tank

A nonstandard flanged and dished head is frequently used in the horizontal storage tank for quick and full access to the internal in oil and gas industry. The head is forged into an elliptical shape with a flat edge at its peripheral. The flat edge serves as a flange while the other mating half coming from the tank shell. The flange pair is installed within a C-shaped clamp and secured by compression bolts at its head side. A gasket is sandwiched between the mating surfaces of the flange pair to provide proper seal. While the head can be removed easily by unscrewing the compression bolts, this disintegrated structure does increase the complexity in component design and unique requirement for installation. The bolt compression load not only affects the pressure capacity of the storage tank, but also governs the stresses in flange pair and C-clamp. In this study, the flanged and dished head assembly has been modeled and analyzed by finite element method for stresses and gasket seal performance subject to installation and operation loads. Both elastic and elastic-plastic analysis has been performed. The tightening force of the bolts is examined against component stresses and gasket seal performance. Optimized bolt load is recommended based on acceptance criteria for stresses and leakage prevention.

Optimization of compound die piercing punches and double cutting process parameters using finite element analysis

This article investigates different types of compound die piercing punches and double cutting operation parameters in terms of optimization using finite element technique, Taguchi method, regression analysis, and analysis of variance. The article overcomes the current knowledge gap in studying various cutting edges of piercing punches such as flat, chamfered, flat edge with concave hemisphere, and convex shaped when using the compound dies in stamping operations. The analysis of the compound die is carried out using ANSYS software. The main focus is to determine the contribution of key parameters for obtaining optimum cutting tool design. The best piercing punch is selected based on minimum burr height of the product. The values of cutting process parameters and burr heights have been analyzed using Minitab software. The results obtained indicate that the burr heights of the final product are at a minimum when the sheet metals are thicker and larger when the sheets are thinner. The chamfered and convex punches provided minimum burr heights which are as low as 0.034 mm for a typical sheet metal. This study provides a better outcome compared to the available experimental data in the literature. The investigation also designed efficient compound dies resulting in improved product quality.

Effective boundary condition for the reflection of shear waves at the periodic rough boundary of an elastic body

We present a homogenization method to treat the problem of the reflection of waves at the free boundary of an elastic body, the edge being structured periodically at the subwavelength scale. The problem is considered for shear waves and the wave equation in the time domain is considered. In the homogenized problem, a boundary condition at an equivalent flat edge is obtained, which links the normal stress to its derivatives, instead of the usual traction free condition. The problem of the position of the equivalent flat boundary with respect to the real roughnesses is addressed and this is done considering the equation of energy conservation in the homogenized problem and considering the accuracy of the homogenized solution when compared to the real one.

Influence of Oblique Edge Blanking on the Online Punching Quality after Stretch Bending

The oblique edge punching was proposed to reduce the surrounding sag failure occurred under the large punching force during online punching after stretch bending. The finite element models under three different kinds of punches were stablished and the punching processes were simulated by using the DEFORM-3D software. Comparison between the flat-edge punch and the oblique edge punches were realized, and the optimal height of the oblique edge of the unilateral bevelled punch and the single-peak bevelled punch were obtained. Three kinds of punches were designed based on the simulation results, and the experiments for manufacturing the upper strip of the automobile door frame by the online punching after stretch bending were carried out. The results show that the depth of the surrounding sag of punching can be reduced significantly and the appearance quality can be improved effectively by the oblique edge blanking. The effect to reduce the depth of surrounding sag failure by the unilateral bevelled punch is better than that by the single-peak bevelled punch, and the depth of surrounding sag failure on the side near the edge tip of the unilateral bevelled punch is smaller than that on the side away from the edge tip.