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Porous silicon (pSi) is an established porous material that offers ample opportunities for biosensor design thanks to its tunable structure, versatile surface chemistry, and large surface area. Nonetheless, its potential for electrochemical sensing is relatively unexplored. This study investigates layered carbon-stabilized pSi nanostructures with site-specific functionalities as an electrochemical biosensor. A double-layer nanostructure combining a top hydrophilic layer of thermally carbonized pSi (TCpSi) and a bottom hydrophobic layer of thermally hydrocarbonized pSi (THCpSi) is prepared. The modified layers are formed in a stepwise process, involving first an electrochemical anodization step to generate a porous layer with precisely defined pore morphological features, followed by deposition of a thin thermally carbonized coating on the pore walls via temperature-controlled acetylene decomposition. The second layer is then generated beneath the first by following the same two-step process, but the acetylene decomposition conditions are adjusted to deposit a thermally hydrocarbonized coating. The double-layer platform features excellent electrochemical properties such as fast electron-transfer kinetics, which underpin the performance of a TCpSi-THCpSi voltammetric DNA sensor. The biosensor targets a 28-nucleotide single-stranded DNA sequence with a detection limit of 0.4 pM, two orders of magnitude lower than the values reported to date by any other pSi-based electrochemical DNA sensor.

The aim of this research is to study the impact of statistical moments of probability density function such as mean, standard deviation, skew of R32 flow maldistribution profile on the thermal performance of microchannel heat exchanger under superheat, and subcooling effect. A mathematical model was developed in order to analyse the influence of the statistical moments of probability density function of R32 flow maldistribution on the thermal performance of microchannel heat exchanger under superheat and sub-cooling effect. It was found that the high standard deviation and high negative skew of R32 flow maldistribution profile gave a large impact on the D of microchannel heat exchanger and can achieve up to 10%. Moreover, it was found that the heat transfer performance of microchannel heat exchanger dropped significantly when the sub-cool increases. In short, low standard deviation, high positive skew, and superheat of a flow maldistribution profile is preferred in order to minimize the performance deterioration effect. An experiment was set up to verify the mathematical model. The results from the mathematical model agreed well within 10% of the experimental data. A performance deterioration correlation related to refrigerant maldistribution under superheat and subcool was developed to provide a faster solution to design an even flow distribution heat exchanger. The proposed correlation in this research offers a quicker and simpler way to study the R32 flow maldistribution problem.

The aim of this research is to study the impact of statistical moments of probability density function such as mean, standard deviation, skew of R32 flow maldistribution profile on the thermal performance of microchannel heat exchanger under superheat, and subcooling effect. A mathematical model was developed in order to analyse the influence of the statistical moments of probability density function of R32 flow maldistribution on the thermal performance of microchannel heat exchanger under superheat and sub-cooling effect. It was found that the high standard deviation and high negative skew of R32 flow maldistribution profile gave a large impact on the D of microchannel heat exchanger and can achieve up to 10%. Moreover, it was found that the heat transfer performance of microchannel heat exchanger dropped significantly when the sub-cool increases. In short, low standard deviation, high positive skew, and superheat of a flow maldistribution profile is preferred in order to minimize the performance deterioration effect. An experiment was set up to verify the mathematical model. The results from the mathematical model agreed well within 10% of the experimental data. A performance deterioration correlation related to refrigerant maldistribution under superheat and subcool was developed to provide a faster solution to design an even flow distribution heat exchanger. The proposed correlation in this research offers a quicker and simpler way to study the R32 flow maldistribution problem.

Angiosperms, http://name.umdl.umich.edu/IC-HERB00IC-X-1531843%5DMICH-V-1531843, https://quod.lib.umich.edu/cgi/i/image/api/thumb/herb00ic/1531843/MICH-V-1531843/!250,250, The University of Michigan Library provides access to these materials for educational and research purposes. Some materials may be protected by copyright. If you decide to use any of these materials, you are responsible for making your own legal assessment and securing any necessary permission. If you have questions about the collection, please contact the Herbarium professional staff: herb-dlps-help@umich.edu. If you have concerns about the inclusion of an item in this collection, please contact Library Information Technology: libraryit-info@umich.edu., https://www.lib.umich.edu/about-us/policies/copyright-policy

Angiosperms, http://name.umdl.umich.edu/IC-HERB00IC-X-1531843%5DMICH-V-1531843, https://quod.lib.umich.edu/cgi/i/image/api/thumb/herb00ic/1531843/MICH-V-1531843/!250,250, The University of Michigan Library provides access to these materials for educational and research purposes. Some materials may be protected by copyright. If you decide to use any of these materials, you are responsible for making your own legal assessment and securing any necessary permission. If you have questions about the collection, please contact the Herbarium professional staff: herb-dlps-help@umich.edu. If you have concerns about the inclusion of an item in this collection, please contact Library Information Technology: libraryit-info@umich.edu., https://www.lib.umich.edu/about-us/policies/copyright-policy