Optimal Design of Heat Exchangers to Enhance Thermal Performance

Heat transfer is a key aspect of devices and industrial processes for maintaining their functionality and achieving better product quality. Heat exchangers of different types and sizes are used to transfer heat between a source and a working fluid to maintain the desirable working temperatures. Due to the space requirements of devices, there is a need for efficient heat exchangers with less size and less weight. Gyroid structure is a type of Triply Periodic Minimal Surface structures that define an internal volume that maximizes surface area and strength while minimizing mass. The hypothesis is that gyroid structures are useful in heat exchanger design, as they can optimize heat transfer to be more efficient, compared to traditional heat exchanger designs. A gyroid structured heat exchanger was designed, 3D printed, and compared to a commercial plate heat exchanger. Using different water flow rates, temperatures at the hot and cold inlets/outlets were measured using thermocouples and PicoLog until they reached steady state and calculated heat transfer rate and efficiency. It is found that heat transfer rate linearly increases with flow rate and that the heat transfer rate for the commercial heat exchanger is about twice the heat transfer rate for the gyroid one. A gyroid heat exchanger with the same surface area as the commercial one is likely to have a much larger heat transfer rate. Additional measurements, such as pressure drop and internal volume, should be taken to properly compare different heat exchangers, while minimizing heat loss and uncertainty in data

Split Aptameric Turn-On Fluorescence Sensor for Detection of Sequence Specific Nucleic Acid at Ambient Temperature

Nucleic acid amplification tests (NAATs) enable sensitive detection of low density infections that microscopy and rapid diagnostic test are not capable of detecting. They enable quantitative and qualitative nucleic acid detection, genotype analysis, and single nucleotide polymorphism (SNP) detection. Current state of the art molecular probes used with NAATs includes molecular beacon (MB), Taqman and its variations. This work presents novel molecular probe designed from Spinach and Dapoxyl aptamers. The aptamers are split into two parts (split aptamer), allowing greater sensitivity and selectivity towards fully complementary nucleic acid analyte. The major advantage of split aptamer probe over state-of-the-art fluorescent probes is its high selectivity: in the presence of a single base mismatched analyte, it produces only background fluorescence, even at room temperature. SSA is a promising tool for label-free analysis of nucleic acids at ambient temperatures. Split spinach aptamer (SSA) probes and split dapoxyl aptamer (SDA) for fluorescent analysis of nucleic acids were designed and tested. In both split aptamer design, two RNA or RNA/DNA or DNA strands hybridized to a specific nucleic acid analyte and formed a binding site for fluorescent dye, which was accompanied by up to 270-fold and 69-fold increase in fluorescence. SSAr consisted entirely of ribonucleotides which potentially be expressed in live cells and used for imaging of specific mRNAs. For in vitro RNA/DNA analysis, SDA consisting of entirely DNA are preferable due to greater chemical stability, lower synthetic cost and reduced ability to form intramolecular structures. Additionally, we designed two DNA strands that function as an adapter for SSA and demonstrated how a single universal spinach aptamer (USSA) probe can be used to detect multiple (potentially any) nucleic acid sequences. USSA can be used for cost-efficient and highly selective analysis of even folded DNA and RNA analytes, as well as for the readout of outputs of DNA logic circuits

Point Anywhere: Directed Object Estimation from Omnidirectional Images

One of the intuitive instruction methods in robot navigation is a pointing gesture. In this study, we propose a method using an omnidirectional camera to eliminate the user/object position constraint and the left/right constraint of the pointing arm. Although the accuracy of skeleton and object detection is low due to the high distortion of equirectangular images, the proposed method enables highly accurate estimation by repeatedly extracting regions of interest from the equirectangular image and projecting them onto perspective images. Furthermore, we found that training the likelihood of the target object in machine learning further improves the estimation accuracy.Comment: Accepted to SIGGRAPH 2023 Poster. Project page: https://github.com/NKotani/PointAnywher