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91.
Puran Pandey Sundar Kunwar Ki-Hoon Shin Min-Kyu Seo Jongwon Yoon Woong-Ki Hong Jung-Inn Sohn 《International journal of molecular sciences》2021,22(22)
In this work, we develop a Ag@Al2O3@Ag plasmonic core–shell–satellite (PCSS) to achieve highly sensitive and reproducible surface-enhanced Raman spectroscopy (SERS) detection of probe molecules. To fabricate PCSS nanostructures, we employ a simple hierarchical dewetting process of Ag films coupled with an atomic layer deposition (ALD) method for the Al2O3 shell. Compared to bare Ag nanoparticles, several advantages of fabricating PCSS nanostructures are discovered, including high surface roughness, high density of nanogaps between Ag core and Ag satellites, and nanogaps between adjacent Ag satellites. Finite-difference time-domain (FDTD) simulations of the PCSS nanostructure confirm an enhancement in the electromagnetic field intensity (hotspots) in the nanogap between the Ag core and the satellite generated by the Al2O3 shell, due to the strong core–satellite plasmonic coupling. The as-prepared PCSS-based SERS substrate demonstrates an enhancement factor (EF) of 1.7 × 107 and relative standard deviation (RSD) of ~7%, endowing our SERS platform with highly sensitive and reproducible detection of R6G molecules. We think that this method provides a simple approach for the fabrication of PCSS by a solid-state technique and a basis for developing a highly SERS-active substrate for practical applications. 相似文献
92.
Adeline E. Williams Gaurav Shrivastava Apostolos G. Gittis Sundar Ganesan Ines Martin-Martin Paola Carolina Valenzuela Leon Ken E. Olson Eric Calvo 《International journal of molecular sciences》2021,22(23)
The PIWI-interacting RNA (piRNA) pathway provides an RNA interference (RNAi) mechanism known from Drosophila studies to maintain the integrity of the germline genome by silencing transposable elements (TE). Aedes aegypti mosquitoes, which are the key vectors of several arthropod-borne viruses, exhibit an expanded repertoire of Piwi proteins involved in the piRNA pathway, suggesting functional divergence. Here, we investigate RNA-binding dynamics and subcellular localization of A. aegypti Piwi4 (AePiwi4), a Piwi protein involved in antiviral immunity and embryonic development, to better understand its function. We found that AePiwi4 PAZ (Piwi/Argonaute/Zwille), the domain that binds the 3′ ends of piRNAs, bound to mature (3′ 2′ O-methylated) and unmethylated RNAs with similar micromolar affinities (KD = 1.7 ± 0.8 μM and KD of 5.0 ± 2.2 μM, respectively; p = 0.05) in a sequence independent manner. Through site-directed mutagenesis studies, we identified highly conserved residues involved in RNA binding and found that subtle changes in the amino acids flanking the binding pocket across PAZ proteins have significant impacts on binding behaviors, likely by impacting the protein secondary structure. We also analyzed AePiwi4 subcellular localization in mosquito tissues. We found that the protein is both cytoplasmic and nuclear, and we identified an AePiwi4 nuclear localization signal (NLS) in the N-terminal region of the protein. Taken together, these studies provide insights on the dynamic role of AePiwi4 in RNAi and pave the way for future studies aimed at understanding Piwi interactions with diverse RNA populations. 相似文献
93.
M. Sundar A. K. Nath D. K. Bandyopadhyay S. P. Chaudhuri P. K. Dey D. Misra 《The International Journal of Advanced Manufacturing Technology》2009,40(9-10):865-874
Samples of mild steel have been cut on a CO2 laser machine using the principle of laser assisted oxygen cutting (LASOX). The combined effects of input process parameters (cutting speed, gas pressure, laser power and stand off distance) on cut quality (heat affected zone (HAZ) width, kerf width and surface roughness) have been studied. Regression analysis has been used to develop models that describe the effect of the independent process parameters on cut quality. Using the developed model, we attempted to optimize the input parameters that would improve the cut quality (minimization of HAZ width, kerf width and surface roughness), increase the productivity and minimize the total operation cost. We found from the study that the gas pressure and cutting speed had pronounced effect on cut quality. Low gas pressure produces lower HAZ width, lower kerf width and good surface finish whereas increase in speed results in higher HAZ width, lower kerf width and good surface finish. 相似文献
94.
M. Sundar P. T. Mativenga L. Li P. L. Crouse 《The International Journal of Advanced Manufacturing Technology》2009,45(11-12):1169-1178
Sustainable manufacturing requires the extended usage of materials and reuse of hard metal tooling. In general, titanium nitride (TiN) coating gives enhanced hardness and wear resistance to the surfaces of engineering tools. However, the high hardness makes it difficult to re-grind or refurbish TiN-coated materials, especially TiN-coated cutting tools. This paper presents the results of laser decoating of TiN from TiN-coated tungsten carbide (WC) substrates. Laser decoating was performed using a KrF excimer laser. The effect of laser fluence, number of pulses, frequency, scanning speed and beam overlap on the decoating performance was investigated in detail. A two-dimensional symmetric finite element model (FEM) was established to elucidate the temperature and stress fields created during the laser decoating process. Successful laser decoating of TiN coating from the WC substrate was demonstrated. It was found that decoating with a laser fluence of 4 J/cm2, scanning speed of 2 mm/s, frequency of 25 Hz and a beam overlap of 91% gives best results for removing an area of TiN coating to its 3 μm thickness. The surface roughness of the best samples was found to be in the order of 0.8–0.9 μm Ra. The experimental and FEM investigation suggested that the decoating of TiN follows combined explosion and evaporation mechanism. 相似文献
95.
Fractal dimension (FD) estimation has become most popular in the field of image analysis and applications; especially estimating the roughness and smoothness of complex objects. In this present investigation, we are considering three most popular methods in the controlled images acquisition experimental setup for eight colored fabrics of the same texture, material property, and illumination. The concept of previous work and the results obtained by this ground truth experiment were discussed to indicate whether FD might be a worth useful metric for the study of color images with self-similarity, such as textures! Interestingly, we found ambiguous FD results here and tried to explain such phenomenon in relation to the development of CIE-based human perception model as texture perception are well associated with the viewing parameters and observer that perceives the image in terms of spatial distribution of color intensity. 相似文献
96.
The ejection of a part following die compaction is a critical step in manufacturing powder metal and ceramic parts as well as pharmaceutical tablets. In this paper, the ejection of die-compacted hollow cylinders of heights 0.5 and 1.2?cm from Fe–2%Cu–0.5%C powders mixed with various amounts of (0.2–0.8?wt-%) of ethylene-bis-stearamide (EBS) was studied to understand the effect of lubricant amount and part geometry on the ejection process. Additionally, the ejection data of gears of 0.5 and 1.2?cm die compacted from Fe–2%Cu–0.5%C powders with 0.8?wt-% EBS was analysed to understand the effect of geometry on the ejection process. Several ejection parameters were found to be sensitive to the amount of EBS as well as the size and shape of the parts. The results from the present study indicated that the major portion of the ejection cycle involved the movement of the part within the die. 相似文献
97.
The market for fruits and vegetables has received considerable interest in recent years, with much of its growth attributed to consumer interest in nutrition and health. Quality has been indicated to be the most important factor in produce sales, and appearance is of noted significance with regard to perceived quality. The broad objectives of this research were to identify the impact of simultaneous colour contrast (i.e. the produce viewed through a mesh bag) on (a) attentive behaviours as measured by eye tracking and (b) perceived quality, visual appeal and purchase intention as measured with a Likert scale. To accomplish these objectives, six different types of produce (red apples, oranges, lemons, green apples, purple onions and white onions) were photographed with four differently coloured mesh treatments: the same (as the produce), complementary, complementary‐analogous and analogous. Visual stimuli were then presented during the eye tracking study and in a subsequent questionnaire. Colour contrast was found to have a significant effect on both resultant eye tracking variables [number of visual fixations (p < 0.001) and time spent (p < 0.001)]. Produce shown with mesh of the same, or an analogous colour, induced significantly more visual fixations and more time than those depicted with complementary or complementary‐analogous treatments. Subsequent to the eye tracking study, subjects were shown the stimuli and asked to rate the expected quality, visual appeal and their purchase intention for the 24 photographs (6 types of produce × 4 colour contrasts) by using a Likert scale. Pairwise comparisons suggested that produce packaged in the same or analogous mesh were perceived by subjects to be of higher quality, more visually appealing and evoked a higher level of purchase intention than those packaged in complementary or complementary‐analogous mesh (α = 0.05). Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
98.
Samita Pattanayak R. N. P. Choudhary Piyush R. Das 《Journal of Materials Science: Materials in Electronics》2013,24(8):2767-2771
The polycrystalline sample of (Bi0.8Gd0.2)FeO3 was prepared by a high-temperature solid-state reaction technique. Preliminary X-ray structural analysis of the sample confirms the formation of the desired compound with rhombohedral phase. The scanning electron micrograph of the sample showed uniform distribution of the plate- and rod-shaped grains. Studies of dielectric and electrical properties of the material were investigated within a wide range of temperature (25–400 °C) and frequency (1 kHz–1 MHz) using complex impedance spectroscopic method. The observation of hysteresis loop of the material confirmed that the material has a ferroelectric property at room temperature. The ac conductivity suggests that the sample obey Jonscher’s universal power law. The dc conductivity follows Arrhenius equation. Detailed studies of ac and dc conductivity show a negative temperature coefficient of resistance (NTCR) behavior of the sample. 相似文献
99.
100.
Similar product designs resemble each other and have similar attributes and characteristics. When examining a product design to create its process plan, design its fixture, or estimate its manufacturing cost, manufacturing engineers often identify one or more similar products that the factory has manufactured in the past. They may do this from memory, from a file cabinet, or from a database (in a product data management system). Then, they retrieve the process plan (or fixture or cost estimate) for the similar product and modify it for the new product. Manufacturing and process planning experts use a complex set of rules, guidelines, and other knowledge to determine how similar two products are. Computer-aided process planning tools, however, generally use simpler, less sophisticated procedures for determining similarity. These traditional procedures may be inappropriate for specific settings. This paper presents an approach for developing function-specific design similarity measures. Such a measure explicitly exploits the specific need for similar products and thus improves variant approaches for process planning, fixture planning, and manufacturability evaluation. The approach is applied to a specific fixture planning domain. 相似文献