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Open Access Publications from the University of California

Scholarly Works (2 results)

  • Thesis
  • Peer Reviewed
UC Riverside Electronic Theses and Dissertations (2016)

The Environmental Protection Agency and European Commission are requiring in-situ on-board diagnostic systems to increase accuracy in monitoring nitrous oxides and particulate matter vehicle emissions. Particulate Matter (PM) sensors are a derivative of this regulation and have been implemented to assess diesel particulate filter failure, as well as solid particle number. The design of PM sensors is varied by company (e.g., Honeywell, Bosch, Emisense, and Delphi) in addition to the applied method. The method of investigation in this study is electrical charging and the capacity for corona discharge generation.

Boltzmann’s Law for charged particles is generally used to predict electrical charging (i.e., particle charging). However, the PM sensor design and method in this study generates a signal that is amplified higher than can be theoretically explained by this law. Signal amplification can only be attributed to ionization due to the presence of corona discharge, besides particle charging in an electric field. A fundamental study probing into the effects of corona discharge on PM sensor signal amplification is necessary to understand the underlying operational principles of the sensor. This study will provide qualitative insights into the electrical properties of PM and the conditions in which electrical properties are influenced by varying physical conditions. The investigation is performed by correlating sensor response to varying physical conditions of PM. The results show that the sensor response is linearly dependent on particle concentration and that signal strength is limited on the sample flow rate. Understanding the operational principles of this design could lead to the development of a relatively inexpensive PM sensor with unprecedented high signal sensitivity.

    Cover page: Diesel Particulate Matter Sensor: Insights Into the Effect of Corona Discharge on Signal AmplificationCreative Commons 'BY-NC-ND' version 4.0 license
    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2019)
    Aminoacyl-tRNA synthetases (ARSs) function to transfer amino acids to cognate tRNA molecules, which are required for protein translation. To date, biallelic mutations in 31 ARS genes are known to cause recessive, early-onset severe multi-organ diseases. VARS encodes the only known valine cytoplasmic-localized aminoacyl-tRNA synthetase. Here, we report seven patients from five unrelated families with five different biallelic missense variants in VARS. Subjects present with a range of global developmental delay, epileptic encephalopathy and primary or progressive microcephaly. Longitudinal assessment demonstrates progressive cortical atrophy and white matter volume loss. Variants map to the VARS tRNA binding domain and adjacent to the anticodon domain, and disrupt highly conserved residues. Patient primary cells show intact VARS protein but reduced enzymatic activity, suggesting partial loss of function. The implication of VARS in pediatric neurodegeneration broadens the spectrum of human diseases due to mutations in tRNA synthetase genes.
      Cover page: Biallelic mutations in valyl-tRNA synthetase gene VARS are associated with a progressive neurodevelopmental epileptic encephalopathyCreative Commons 'BY' version 4.0 license
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