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Open Access Publications from the University of California

Scholarly Works (24 results)

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

Modern and future mobile devices must support increasingly more wireless standards and bands. Currently, multi-band coexistence is enabled by a network of discrete, off-chip components that are bulky, expensive, and narrowband. As transceivers are required to accommodate an increasing number of wireless bands, the required number of discrete components increases accordingly, resulting in greater bill of materials (BoM) cost and front-end module (FEM) area. This work focuses on design techniques to enable front-end integration and reconfigurability in multi-band radios.

In the first part of this work, we present a wideband spectrum sensing receiver with high sensitivity, wide dynamic range, and low power overhead. Reconfigurability in multi-band radios requires environmental awareness, and spectrum sensing can be used for optimal channel selection and adaptive interference suppression. The 300MHz-700MHz spectrum sensing receiver uses subsampling downconversion and digital-analog hybrid correlation to achieve -104dBm sensitivity and 84dB dynamic range for a 6MHz channel while consuming only 28mW of power. In the second part of this work, we present a wideband time division duplex (TDD) front-end with an innovative transmit/receive (T/R) switching scheme. T/R switches conventionally are off-chip components, and existing integrated designs have been narrowband or high loss. We propose a wideband integrated T/R switching technique in which the PA is re-used as an LNA during receive mode, and we demonstrate this in a 20dBm polar transmitter that can be re-purposed into a 3.4GHz-5.4GHz LNA achieving -6.7dBm P1dB and 5.1dB NF. The two systems presented in this thesis contribute key innovations towards fundamental aspects of future reconfigurable radios - greater front-end integration, wideband transceiver design, and spectrum awareness.

    Cover page: Design of Reconfigurable Radio Front-Ends
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2022)
    Photoplethysmography (PPG) is garnering substantial interest due to low cost, noninvasiveness, and its potential for diagnosing cardiovascular diseases, such as cardiomyopathy, heart failure, and arrhythmia. The signals obtained through PPG can yield information based on simple analyses, such as heart rate. In contrast, when accompanied by the complex analysis of sophisticated signals, valuable information, such as blood pressure, sympathetic nervous system activity, and heart rate variability, can be obtained. For a complex analysis, a better understanding of the sources of noise, which create limitations in the application of PPG, is needed to get reliable information to assess cardiovascular health. Therefore, this Special Issue handles literature about noises and how they affect the waveform of the PPG caused by individual variations (e.g., skin tone, obesity, age, and gender), physiology (e.g., respiration, venous pulsation, body site of measurement, and body temperature), and external factors (e.g., motion artifact, ambient light, and applied pressure to the skin). It also covers the issues that still need to be considered in each situation.
      Cover page: Advances in Photoplethysmography for Personalized Cardiovascular Monitoring
      • Article
      • Peer Reviewed
      UCLA Previously Published Works (2024)
      A novel living biointerface that integrates living biological and hydrogel systems, can significantly improve monitoring and treatment through enhanced interaction with biological tissues, revolutionizing our chronic inflammation management.
        Cover page: A seamless living biointerface for inflammation management.
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2022)
        Mass transfer is an essential factor determining photocatalytic performance, which can be modulated by fluid field via manipulating the kinetic characteristics of photocatalysts and photocatalytic intermediates. Past decades have witnessed the efforts and achievements made in manipulating mass transfer based on photocatalyst structure and composition design, and thus, a critical survey that scrutinizes the recent progress in this topic is urgently necessitated. This review examines the basic principles of how mass transfer behavior impacts photocatalytic activity accompanying with the discussion on theoretical simulation calculation including fluid flow speed and pattern. Meanwhile, newly emerged viable photocatalytic micro/nanomotors with self-thermophoresis, self-diffusiophoresis, and bubble-propulsion mechanisms as well as magnet-actuated photocatalytic artificial cilia for facilitating mass transfer will be covered. Furthermore, their applications in photocatalytic hydrogen evolution, carbon dioxide reduction, organic pollution degradation, bacteria disinfection and so forth are scrutinized. Finally, a brief summary and future outlook are presented, providing a viable guideline to those working in photocatalysis, mass transfer, and other related fields.
          Cover page: Fluid Field Modulation in Mass Transfer for Efficient Photocatalysis
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2016)

          Purpose

          The effect of an oral trans-resveratrol-based supplement (Longevinex®) on choroidal thickness, measured using optical coherence tomography (OCT) enhanced depth imaging, was investigated in a prospective study.

          Materials and methods

          34 young, healthy participants were randomly divided into two age- and gender-matched groups. They were then assigned in a randomized fashion to treat with either a trans-resveratrol-based group (Longevinex®, Las Vegas) or placebo. All participants underwent ocular imaging with spectral domain (SD)-OCT (Spectralis; Heidelberg Engineering, Heidelberg) at the baseline and then again 1 h following treatment. The choroidal thickness was measured in a masked fashion at the fovea and at four additional points, located at 500 μm and 1000 μm nasal to the fovea and 500 μm and 1000 μm temporal to the fovea.

          Results

          In the resveratrol group, the foveal choroidal thickness at the baseline was 267.73 ± 84.19 μm (mean ± SD); it increased to 284.57 ± 92.39 μm 1 h after drug treatment (p = 0.033). The mean choroidal thickness was also significantly increased at each of the four extrafoveal points (all p < 0.05). In the control group, the mean baseline choroidal thickness at the fovea was 269.73 ± 71.40 μm (mean ± SD) and it was 268.43 ± 70.15 μm (mean ± SD) 1 h after the placebo was administered (p = 0.183); there were also no significant differences in choroidal thickness at the four additional points (all p > 0.05) Conclusion: A significant increase in choroidal thickness following oral administration of a trans-resveratrol-based supplement was observed. There was no change in choroidal thickness in the placebo-treated control group. We speculate that the increased choroidal thickness is the result of choroidal vessel vasodilation.
            Cover page: Effect of Resveratrol-Based Nutritional Supplement on Choroidal Thickness: A Pilot Study
            • Article
            • Peer Reviewed
            UCLA Previously Published Works (2021)
            Physiological monitoring sensors have been critical in diagnosing and improving the healthcare industry over the past 30 years, despite various limitations regarding providing differences in signal outputs in response to the changes in the user's body. Four-dimensional (4D) printing has been established in less than a decade; therefore, it currently offers limited resources and knowledge. Still, the technique paves the way for novel platforms in today's ever-growing technologies. This innovative paradigm of 4D printing physiological monitoring sensors aspires to provide real-time and continuous diagnoses. In this perspective, we cover the advancements currently available in the 4D printing industry that has arisen in the last septennium, focusing on the overview of 4D printing, its history, and both wearable and implantable physiological sensing solutions. Finally, we explore the current challenges faced in this field, translational research, and its future prospects. All of these aims highlight key areas of attention that can be applied by future researchers to fully transform 4D printed physiological monitoring sensors into more viable medical products.
              Cover page: Advances in 4D‐printed physiological monitoring sensors
              • Article
              • Peer Reviewed
              UC Davis Previously Published Works (2022)
              Dating mafic igneous rocks (silica-undersaturated) is difficult for the lack of suitable minerals such as zircons (ZrSiO4) commonly found in the sialic rocks such as granites. In this regard, baddeleyite (ZrO2) has been long recognized as the most important mineral to serve as a geochronometer for dating silica-undersaturated igneous rocks. However, separating baddeleyite is difficult due to its small grain size, typical tabular morphology, and low abundance in samples. The standard water-based separation technique requires kilogram-sized samples and usually has a very low recovery rate. In this study, a new separation method based on the different solubilities of the minerals within HF + HCl + HNO3 reagents was developed to achieve a high recovery of baddeleyite. With ∼19 g of diabase powder, the new method recovers 150-160 baddeleyite grains of 10-100 μm length and 4-50 μm width, an order of magnitude improvement over the water-based separation method, which typically recovers 11-12 similarly sized baddeleyite grains out of the ∼19 g sample. Subsequent secondary ion mass spectrometry U-Pb analyses demonstrate that the baddeleyite grains recovered by the new separation method keep the U-Pb system closed, indicating no Pb loss during acid treatment. Thus, this new method enables the most efficient baddeleyite recovery from gram-sized rocks and is anticipated to greatly contribute to the geochronological study of silica-unsaturated mafic rocks.
                Cover page: An Acid-Based Method for Highly Effective Baddeleyite Separation from Gram-Sized Mafic Rocks
                • Article
                • Peer Reviewed
                UC San Francisco Previously Published Works (2015)

                Background

                Protein tyrosine phosphatase receptor type D (PTPRD) is a putative tumor suppressor in several cancers including head and neck squamous cell carcinoma (HNSCC). STAT3 is a frequently hyperactivated oncogene in HNSCC. As STAT3 is a direct substrate of PTPRD, we sought to determine the genetic or epigenetic alterations of PTPRD that contribute to overactive STAT3 in HNSCC.

                Methods

                We analyzed data from The Cancer Genome Atlas (TCGA) and our previous whole-exome sequencing study and summarized the mutation, methylation, and copy number status of PTPRD in HNSCC and other cancers. In vitro studies involved standard transfection and MTT protocols, as well as methylation-specific PCR.

                Results

                Our findings indicate that PTPRD mutation, rather than methylation or copy number alteration, is the primary mechanism by which PTPRD function is lost in HNSCC. We demonstrate that overexpression of wild-type PTPRD in HNSCC cells significantly inhibits growth and STAT3 activation while PTPRD mutants do not, suggesting that mutation may lead to loss of function and subsequent hyper-phosphorylation of PTPRD substrates, especially STAT3. Importantly, we determined that HNSCC cells harboring an endogenous PTPRD mutation are more sensitive to STAT3 blockade than PTPRD wild-type cells. We additionally found that PTPRD mRNA expression does not correlate with pSTAT3 expression, suggesting that alterations that manifest through altered mRNA expression, including hypermethylation and gene copy number alterations, do not significantly contribute to STAT3 overactivation in HNSCC.

                Conclusion

                PTPRD mutation, but not methylation or copy number loss, may serve as a predictive biomarker of sensitivity to STAT3 inhibitors in HNSCC.
                  Cover page: Loss-of-Function PTPRD Mutations Lead to Increased STAT3 Activation and Sensitivity to STAT3 Inhibition in Head and Neck Cancer
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2021)
                  Magnetoelastic effect characterizes the change of materials' magnetic properties under mechanical deformation, which is conventionally observed in some rigid metals or metal alloys. Here we show magnetoelastic effect can also exist in 1D soft fibers with stronger magnetomechanical coupling than that in traditional rigid counterparts. This effect is explained by a wavy chain model based on the magnetic dipole-dipole interaction and demagnetizing factor. To facilitate practical applications, we further invented a textile magnetoelastic generator (MEG), weaving the 1D soft fibers with conductive yarns to couple the observed magnetoelastic effect with magnetic induction, which paves a new way for biomechanical-to-electrical energy conversion with short-circuit current density of 0.63 mA cm-2, internal impedance of 180 Ω, and intrinsic waterproofness. Textile MEG was demonstrated to convert the arterial pulse into electrical signals with a low detection limit of 0.05 kPa,  even with heavy perspiration or in underwater situations without encapsulations.
                    Cover page: Soft fibers with magnetoelasticity for wearable electronics.
                    • Article
                    • Peer Reviewed
                    UCLA Previously Published Works (2021)
                    Electronic textiles (e-textiles), having the capability of interacting with the human body and surroundings, are changing our everyday life in fundamental and meaningful ways. Yet, the expansion of the field of e-textiles is still limited by the lack of stable and biocompatible power sources with aesthetic designs. Here, we report a rechargeable solid-state Zn/MnO2 fiber battery with stable cyclic performance exceeding 500 hours while maintaining 98.0% capacity after more than 1000 charging/recharging cycles. The mechanism of the high electrical and mechanical performance due to the graphene oxide–embedded polyvinyl alcohol hydrogel electrolytes was rationalized by Monte Carlo simulation and finite element analysis. With a collection of key features including thin, light weight, economic, and biocompatible as well as high energy density, the Zn/MnO2 fiber battery could seamlessly be integrated into a multifunctional on-body e-textile, which provides a stable power unit for continuous and simultaneous heart rate, temperature, humidity, and altitude monitoring.
                      Cover page: An ultrathin rechargeable solid-state zinc ion fiber battery for electronic textiles
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