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Open Access Publications from the University of California

Scholarly Works (11 results)

  • Article
LBL Publications (2001)

The ideal structural steel combines high strength with high fracture toughness. This dissertation discusses the governing principles of strength and toughness, along with the approaches that can be used to improve these properties and the inherent limits to how strong and tough a steel can be.

    Cover page: The limit of strength and toughness of steel
    • Article
    LBL Publications (2001)
      Cover page: The Limit of Strength and Toughness of SteelCreative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2002)

      The rice disease resistance gene, Xa21, encodes a receptor kinase-like protein consisting of leucine-rich repeats in the putative extracellular domain and a serine/threonine kinase in the putative intracellular domain. The putative XA21 kinase domain was expressed as maltose-binding and glutathione S-transferase fusion proteins in Escherichia coli. The fusion proteins are capable of autophosphorylation. Phosphoamino acid analysis of the glutathione S-transferase fusion protein indicates that only serine and threonine residues are phosphorylated. The relative phosphorylation rate of the XA21 kinase against increasing enzyme concentrations follows a first-order rather than second-order kinetics, indicating an intramolecular phosphorylation mechanism. Moreover, the active XA21 kinase cannot phosphorylate a kinase-deficient mutant of XA21 kinase. The enzymatic activity of the XA21 kinase in a buffer containing Mn(2+) is at least 15 times higher than that with Mg(2+). The K(m) and V(max) of XA21 kinase for ATP are 0.3 microm and 8.4 nmol/mg/min, respectively. Tryptic phosphopeptide mapping reveals that multiple sites on the XA21 kinase are phosphorylated. Finally, our data suggest that the region of XA21 kinase corresponding to the RD kinase activation domain is not phosphorylated, revealing a distinct mode of action compared with the tomato Pto serine/threonine kinase conferring disease resistance.

        Cover page: Biochemical characterization of the kinase domain of the rice disease resistance receptor-like kinase XA21.
        • Article
        • Peer Reviewed
        UCLA Previously Published Works (2021)
        We have previously demonstrated a novel role of bone morphogenic protein 4 (BMP4) in inducing NOX1-dependent endothelial nitric oxide synthase (eNOS) uncoupling, endothelial dysfunction, and inflammatory activation in type 2 diabetes mellitus (T2DM). However, how BMP4 activates NOX1 and whether targeting the new mechanistic pathway revealed is effective in preserving endothelial function in T2DM remains unclear. In this study, we observed that BMP4 induced a marked, time-dependent increase in physiological binding between TLR2 and NOX1 in aortic endothelial cells as well as increased binding of TLR2 to NOXO1. In TLR2 knockout (Tlr2 -/-) mice fed high-fat diet, body weight gain was significantly less compared with wild-type (WT) mice both in males and females. The high-fat diet-induced increases in fasting blood glucose levels, as well as in circulating insulin and leptin levels, were absent in Tlr2 -/- mice. High-fat feeding induced increases in overall fat mass, and in fat mass of different pockets were abrogated in Tlr2 -/- mice. Whereas energy intake was similar in high-fat-fed WT and Tlr2 -/- mice, TLR2 deficiency resulted in higher energy expenditure attributable to improved physical activity, which was accompanied by restored skeletal muscle mitochondrial function. In addition, TLR2 deficiency recoupled eNOS, reduced total superoxide production, improved H4B and NO bioavailabilities in aortas, and restored endothelium-dependent vasorelaxation. Collectively, our data strongly indicate that TLR2 plays important roles in the development of metabolic features of T2DM and its related endothelial/vascular dysfunction. Therefore, targeting TLR2 may represent a novel therapeutic strategy for T2DM, obesity, and cardiovascular complications via specific inhibition of NOX1.
          Cover page: Toll-Like Receptor 2 (TLR2) Knockout Abrogates Diabetic and Obese Phenotypes While Restoring Endothelial Function via Inhibition of NOX1.
          • Article
          • Peer Reviewed
          UC Berkeley Previously Published Works (2019)
          One dimensional boron nitride (BN) nanomaterials with a high aspect ratio are of great interest due to their unique properties and potential applications. However, BN nanomaterials are generally difficult to synthesize. Here, we describe the creation of arrays of vertically aligned pure BN nanofibers and BN coated carbon nanofibers, fabricated on-chip via a straightforward template-assisted chemical conversion reaction. The template, a glassy carbon nanofiber array, is produced by plasma processing of conventional photoresists. The method is highly controllable, patternable, and scalable, and the final arrays can be fabricated over large areas with a controlled fiber length. We characterize the electron field emission properties of the BN-coated carbon nanofiber array and find a large field enhancement factor, low turn-on voltage, and good stability. The outstanding field emission performance results from the small tip size and high aspect ratio of the nanofiber as well as the high chemical stability and high thermal conductivity of the BN coating.
            Cover page: Wafer-scale on-chip synthesis and field emission properties of vertically aligned boron nitride based nanofiber arrays
            • Article
            • Peer Reviewed
            UCLA Previously Published Works (2016)

            Introduction

            Pregnant women exposed to tobacco smoke predispose the offspring to many adverse consequences including an altered lung development and function. There is no effective therapeutic intervention to block the effects of smoke exposure on the developing lung. Clinical and animal studies demonstrate that acupuncture can modulate a variety of pathophysiological processes, including those involving the respiratory system; however, whether acupuncture affects the lung damage caused by perinatal smoke exposure is not known.

            Methods

            To determine the effect of acupuncture on perinatal nicotine exposure on the developing lung, pregnant rat dams were administered (1) saline, (2) nicotine, or (3) nicotine + electroacupuncture (EA). Nicotine was administered (1 mg/kg subcutaneously) once a day and EA was applied to both "Zusanli" (ST 36) points. Both interventions were administered from gestational day 6 to postnatal day 21 (PND21), following which pups were sacrificed. Lungs, blood, and brain were collected to examine markers of lung injury, repair, and hypothalamic pituitary adrenal (HPA) axis.

            Results

            Concomitant EA application blocked nicotine-induced changes in lung morphology, lung peroxisome proliferator-activated receptor γ and wingless-int signaling, two key lung developmental signaling pathways, hypothalamic pituitary adrenal axis (hypothalamic corticotropic releasing hormone and lung glucocorticoid receptor levels), and plasma β-endorphin levels.

            Conclusions

            Electroacupuncture blocks the nicotine-induced changes in lung developmental signaling pathways and the resultant myogenic lung phenotype, known to be present in the affected offspring. We conclude that EA is a promising novel intervention against the smoke exposed lung damage to the developing lung.
              • Article
              • Peer Reviewed
              UCLA Previously Published Works (2024)
              Systemic amyloidosis involves the deposition of misfolded proteins in organs/tissues, leading to progressive organ dysfunction and failure. Congo red is the gold-standard chemical stain for visualizing amyloid deposits in tissue, showing birefringence under polarization microscopy. However, Congo red staining is tedious and costly to perform, and prone to false diagnoses due to variations in amyloid amount, staining quality and manual examination of tissue under a polarization microscope. We report virtual birefringence imaging and virtual Congo red staining of label-free human tissue to show that a single neural network can transform autofluorescence images of label-free tissue into brightfield and polarized microscopy images, matching their histochemically stained versions. Blind testing with quantitative metrics and pathologist evaluations on cardiac tissue showed that our virtually stained polarization and brightfield images highlight amyloid patterns in a consistent manner, mitigating challenges due to variations in chemical staining quality and manual imaging processes in the clinical workflow.
                Cover page: Virtual birefringence imaging and histological staining of amyloid deposits in label-free tissue using autofluorescence microscopy and deep learning.
                • Article
                • Peer Reviewed
                UC Berkeley Previously Published Works (2023)
                The recently emerged ferromagnetic two-dimensional (2D) materials provide unique platforms for compact spintronic devices down to the atomic-thin regime; however, the prospect is hindered by the limited number  of ferromagnetic 2D materials discovered with limited choices of magnetic properties. If 2D antiferromagnetism could be converted to 2D ferromagnetism, the range of 2D magnets and their potential applications would be significantly broadened. Here, we discovered emergent ferromagnetism by interfacing non-magnetic WS2 layers with the antiferromagnetic FePS3. The WS2 exhibits an order of magnitude enhanced Zeeman effect with a saturated interfacial exchange field ~38 Tesla. Given the pristine FePS3 is an intralayer antiferromagnet, the prominent interfacial exchange field suggests the formation of ferromagnetic FePS3 at interface. Furthermore, the enhanced Zeeman effect in WS2 is found to exhibit a strong WS2-thickness dependence, highlighting the layer-tailorable interfacial exchange coupling in WS2-FePS3 heterostructures, which is potentially attributed to the thickness-dependent interfacial hybridization.
                  Cover page: Ferromagnetism emerged from non-ferromagnetic atomic crystals.
                  • Article
                  • Peer Reviewed
                  UC Irvine Previously Published Works (2016)

                  Objective

                  Inflammation plays a key role in the pathophysiological processes after intracerebral hemorrhage (ICH). Post-ICH macrophages infiltrate the brain and release pro-inflammatory factors (tumor necrosis factor-α), amplifying microglial activation and neutrophil infiltration. Platelet-derived growth factor receptor-β (PDGFR-β) is expressed on macrophages and it's activation induces the recruitment of macrophages. Platelet-derived growth factor-D (PDGF-D) is an agonist with a significantly higher affinity to the PDGFR-β compared to another isoform of the receptor. In this study, we investigated the role of PDGF-D in the pro-inflammatory response after ICH in mice.

                  Methods

                  A blood injection model of ICH was used in eight-week old male CD1 mice (weight 30g). Some mice received an injection of plasmin or PDGF-D. Gleevec, a PDGFR inhibitor, was administered at 1, 3 or 6h post-ICH. Plasmin was administered with or without PDGF-D siRNAs mixture or scramble siRNA. A plasmin-antagonist, ε-Aminocaproic acid (EACA), was co-administrated with the blood. The effects of ICH and treatment on the brain injury and post-ICH inflammation were investigated.

                  Results

                  ICH resulted in the overexpression of PDGF-D, associated with the infiltration of macrophages. PDGFR-inhibition decreased ICH-induced brain injury, attenuating macrophage and neutrophil infiltration, reducing microglial activation and TNF-α production. Administration of recombinant PDGF-D induced TNF-α production, and PDGFR-inhibition attenuated it. A plasmin-antagonist suppressed PDGFR-β activation and microglial activation. Plasmin increased PDGF-D expression, and PDGF-D inhibition reduced neutrophil infiltration.

                  Conclusion

                  ICH-induced PDGF-D accumulation contributed to post-ICH inflammation via PDGFR activation and enhanced macrophage infiltration. The inhibition of PDGFR had an anti-inflammatory effect. Plasmin is a possible upstream effector of PDGF-D. The targeting of PDGF-D may provide a novel way to decrease brain injury after ICH.
                    Cover page: Role of PDGF-D and PDGFR-β in neuroinflammation in experimental ICH mice model
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2006)

                    XA21 is a receptor-like kinase protein in rice (Oryza sativa) that confers gene-for-gene resistance to specific races of the causal agent of bacterial blight disease, Xanthomonas oryzae pv oryzae. We identified XA21 binding protein 3 (XB3), an E3 ubiquitin ligase, as a substrate for the XA21 Ser and Thr kinase. The interaction between XB3 and the kinase domain of XA21 has been shown in yeast and in vitro, and the physical association between XB3 and XA21 in vivo has also been confirmed by coimmunoprecipitation assays. XB3 contains an ankyrin repeat domain and a RING finger motif that is sufficient for its interaction with the kinase domain of XA21 and for its E3 ubiquitin ligase activity, respectively. Transgenic plants with reduced expression of the Xb3 gene are compromised in resistance to the avirulent race of X. oryzae pv oryzae. Furthermore, reduced levels of Xb3 lead to decreased levels of the XA21 protein. These results indicate that Xb3 is necessary for full accumulation of the XA21 protein and for Xa21-mediated resistance.

                      Cover page: Rice XA21 binding protein 3 is a ubiquitin ligase required for full Xa21-mediated disease resistance.
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