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Open Access Publications from the University of California

Scholarly Works (23 results)

  • Article
LBL Publications (1989)
    Cover page: A Heat and Mass Transfer Model for Thermal and Hydraulic Calculations of Indirect Evaporative Cooler Performance
    • Article
    • Peer Reviewed
    UCLA Previously Published Works (2010)
    In this study, we have developed an integrated microfluidic platform for actively patterning mammalian cells, where poly(ethylene glycol) (PEG) hydrogels play two important roles as a non-fouling layer and a dielectric structure. The developed system has an embedded array of PEG microwells fabricated on a planar indium tin oxide (ITO) electrode. Due to its dielectric properties, the PEG microwells define electrical energy landscapes, effectively forming positive dielectrophoresis (DEP) traps in a lowconductivity environment. Distribution of DEP forces on a model cell was first estimated by computationally solving quasi-electrostatic Maxwell's equations, followed by an experimental demonstration of cell and particle patterning without an external flow. Furthermore, efficient patterning of mouse embryonic stem (mES) cells was successfully achieved in combination with an external flow. With a seeding density of 107 cells/mL and a flow rate of 3 μL/min, trapping of cells in the microwells was completed in tens of seconds after initiation of the DEP operation. Captured cells subsequently formed viable and homogeneous monolayer patterns. This simple approach could provide an efficient strategy for fabricating various cell microarrays for applications such ascell-based biosensors, drug discovery, and cell microenvironment studies. © 2010 The Author(s).
      Cover page: Efficient dielectrophoretic patterning of embryonic stem cells in energy landscapes defined by hydrogel geometries
      • Article
      LBL Publications (2008)

      This report discusses the AC losses in the MICE channel magnets during magnet charging and discharging. This report talks about the three types of AC losses in the MICE magnets; the hysteretic AC loss in the superconductor, the coupling AC loss in the superconductor and the eddy current AC loss in the magnet mandrel and support structure. AC losses increase the heat load at 4 K. The added heat load increases the temperature of the second stage of the cooler. In addition, AC loss contributes to the temperature rise between the second stage cold head and the high field point of the magnet, which is usually close to the magnet hot spot. These are the curses of AC loss in the MICE magnet that can limit the rate at which the magnet can be charge or discharged. If one is willing to allow some of the helium that is around the magnet to boil away during a magnet charge or discharge, AC losses can become a blessing. The boil off helium from the AC losses can be used to cool the upper end of the HTS leads and the surrounding shield. The AC losses are presented for all three types of MICE magnets. The AC loss temperature drops within the coupling magnet are presented as an example of how both the curse and blessing of the AC losses can be combined.

        Cover page: AC Losses in the MICE Channel Magnets -- Is This a Curse or a Blessing?
        • Article
        • Peer Reviewed
        UC San Francisco Previously Published Works (2013)
        The phosphatase and tumor suppressor PTEN inhibits the phosphoinositol-3-kinase (PI3K) signaling pathway and plays a key role in cell growth, proliferation, survival, and migration. Pten conditional deletion using MxCre or Scl-CreERT leads to splenomegaly
          • Article
          • Peer Reviewed
          LBL Publications (2008)

          The MICE cooling channel consists of alternating three absorber focus coil module (AFC) and two RF coupling coil module (RFCC) where the process of muon cooling and reacceleration occurs. The RFCC module comprises a superconducting coupling solenoid mounted around four conventional conducting 201.25 MHz closed RF cavities and producing up to 2.2T magnetic field on the centerline. The coupling coil magnetic field is to produce a low muon beam beta function in order to keep the beam within the RF cavities. The magnet is to be built using commercial niobium titanium MRI conductors and cooled by pulse tube coolers that produce 1.5 W of cooling capacity at 4.2 K each. A self-centering support system is applied for the coupling magnet cold mass support, which is designed to carry a longitudinal force up to 500 kN. This report will describe the updated design for the MICE coupling magnet. The cold mass support system and helium cooling system are discussed in detail.

            Cover page: The Helium Cooling System and Cold Mass Support System for the MICE Coupling Solenoid
            • Article
            • Peer Reviewed
            UCLA Previously Published Works (2019)
            Purpose: To develop a phantom with optical and thermal properties matched to human prostate. This phantom will provide a platform for the development and characterization of 980 nm laser interstitial thermal therapy (LITT) systems. Methods: A polyacrylamide gel was doped with Naphthol Green B, Intralipid, and Bovine Serum Albumin (BSA). The necessary concentration of each ingredient was determined by measuring the optical properties via fluence measurements and light diffusion theory. LITT was then performed under the same conditions as a previous clinical trial in which temperature was monitored via a thermal probe. The thermal data and induced coagulation zone were compared to clinical data to illustrate the similarity between the phantom and patient. LITT was also performed under magnetic resonance thermometry (MRT). Results: The requisite concentrations of Naphthol Green B, Intralipid and BSA were found to be 0.144% (w/v), 8.06% (v/v) and 31.4% (v/v) respectively. In the native state, the absorption coefficient and reduced scattering coefficient ( μs' ) were found to be 0.66 ± 0.06 cm-1 and 8.27 ± 0.50 cm-1 respectively, with μs' increasing to 17.63 ± 1.41 cm-1 after coagulation. The thermal response of the phantom was similar to that observed clinically with maximum thermal probe measurements of 64.2 °C and 66.9 °C respectively. The shape of the induced coagulation zone was qualitatively and quantitatively similar to the MRT zone of elevated temperature and the coagulation zone observed clinically. Conclusions: A phantom which simulates optical and thermal response to 980 nm LITT was constructed and demonstrated to be similar to human prostate.
              Cover page: A tissue-mimicking prostate phantom for 980 nm laser interstitial thermal therapy
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (1995)
              Transcription of the macrophage scavenger receptor A gene is markedly upregulated during monocyte to macrophage differentiation. In these studies, we demonstrate that 291 bp of the proximal scavenger receptor promoter, in concert with a 400-bp upstream enhancer element, is sufficient to direct macrophage-specific expression of a human growth hormone reporter in transgenic mice. These regulatory elements, which contain binding sites for PU.1, AP-1, and cooperating ets-domain transcription factors, are also sufficient to mediate regulation of transgene expression during the in vitro differentiation of bone marrow progenitor cells in response to macrophage colony-stimulating factor. Mutation of the PU.1 binding site within the scavenger receptor promoter severely impairs transgene expression, consistent with a crucial role of PU.1 in regulating the expression of the scavenger receptor gene. The ability of the scavenger receptor promoter and enhancer to target gene expression to macrophages in vivo, including foam cells of atherosclerotic lesions, suggests that these regulatory elements will be of general utility in the study of macrophage differentiation and function by permitting specific modifications of macrophage gene expression.
                • Article
                LBL Publications (1995)
                  Cover page: Angle-Resolved Photoemission Extended Fine Structure: Multiple Layers of Emitters and Multiple Initial States
                  • Article
                  • Peer Reviewed
                  UCLA Previously Published Works (2021)
                    Cover page: Stiff and strong, lightweight bi-material sandwich plate-lattices with enhanced energy absorption
                    • Article
                    • Peer Reviewed
                    UCLA Previously Published Works (2019)

                    Background and purpose

                    Fractional flow measured on 3D-TOF-MRA was proposed to quantify cerebral hemodynamic changes in patients with artery stenosis. We investigated the association between fractional flow and cerebral perfusion changes in patients with symptomatic MCA stenosis.

                    Materials and methods

                    This prospective study was approved by the institutional review board, and all participants provided written informed consent. From June 2015 to May 2018, four hundred twenty-nine patients with symptomatic intracranial arterial stenosis were consecutively recruited and underwent conventional brain MR imaging, 3D-TOF-MRA, and brain CTP. A total of 91 patients with unilateral M1 segment stenosis of the MCA and a stenosis degree of 50%∼99% were included in the analysis. Fractional flow was measured by comparing distal and proximal signal intensity changes across the stenosis on 3D-TOF-MRA. The cutoff value for fractional flow for discriminating between normal perfusion and hypoperfusion was obtained from the receiver operating characteristic curve. Associations between fractional flow and hypoperfusion were assessed using univariate and multivariate analyses.

                    Results

                    The receiver operating characteristic curve showed a significant fractional flow threshold value at 0.90 (sensitivity, 70.1%; 95% CI, 55.9%-81.2%; specificity, 69.6%; 95% CI, 47.6%-84.1%). Participants with a fractional flow of ≤0.90 were independently associated with cerebral hypoperfusion downstream from the stenosis site (adjusted OR, 3.68; 95% CI, 1.63-11.62; P = .027).

                    Conclusions

                    Fractional flow measured on 3D-TOF-MRA may serve as a noninvasive and practical tool for determining the cerebral hypoperfusion in patents with symptomatic MCA stenosis.
                      Cover page: Association of Fractional Flow on 3D-TOF-MRA with Cerebral Perfusion in Patients with MCA Stenosis
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