Young Jin Choi

Sejong University, Sŏul, Seoul, South Korea

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Publications (213)530.36 Total impact

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    ABSTRACT: Correction for ‘Surface group modification and carrier transport properties of layered transition metal carbides (Ti2CTx, T: –OH, –F and –O)’ by Shen Lai, et al., Nanoscale, 2015, DOI: 10.1039/c5nr06513e.
    No preview · Article · Jan 2016 · Nanoscale
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    ABSTRACT: Purpose: The objective of this phase II study was to assess the clinical antitumor activity and toxicities of docetaxel and cisplatin chemotherapy, in patients with locally advanced and metastatic, recurrent squamous cell carcinomas of the head and neck (SCCHN). Materials and methods: All eligible patients with locally advanced and metastatic, recurrent SCCHN had received two courses of chemotherapy followed by repeated head and neck examinations and computed tomography. Patients who had received prior chemotherapy with taxanes were ineligible. If the patients achieved a response (either CR or PR), they received one more course of chemotherapy prior to undergoing definitive local treatment. The combination chemotherapy consisted of docetaxel, 70 mg/m2, and cisplatin, 75 mg/m2, on day 1, with the cycles repeated every 3~4 weeks. Results: All 32 patients were assessable for response and toxicity analyses. The most common grade 3/4 adverse event was neutropenia, which occurred in 11% of cases. No febrile neutropenia was noticed. The other grade 3/4 adverse events included: anemia (2%) and stomatitis (3%). The response rate in patients with locally advanced cancer was 19/21 (90%). Fifteen patients (71%) achieved a CR and 4 (19%) a PR. Out of the 4 patients presenting with a distant metastatic disease, 1 each achieved CR and PR, with 2 stable disease (SD). Out of the 7 patients with a recurrence at a distant site, 1 each achieved PR and SD, and 5 (71%) had a progression of the disease (PD). The overall response rate was 22/32 (69%). Conclusion: Docetaxel plus cisplatin is an effective regimen with an acceptable toxicity profile. This regimen may offer high antitumor activity on short outpatient administration, with a low incidence of severe toxicity.
    Preview · Article · Dec 2015 · Cancer Research and Treatment
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    ABSTRACT: A simple Au/MeNH3PbI3-xClx/fluorine-doped tin oxide device exhibits remarkable bipolar and bistable resistive switching behavior with small on-off voltage of less than 1 V.
    No preview · Article · Dec 2015 · ChemInform
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    ABSTRACT: In this study, a new type of targeted bacteriobots is prepared and investigated as a therapeutic strategy against solid tumors. Maleimide-functionalized hyaluronic acid (HA) polymer is synthesized and cross-linked with four-arm-thiolated polyethylene glycol (PEG-SH) to form HA microbeads with diameter of 8 μm through the Michael-type addition. Docetaxel (DTX)-loaded nanoparticles are encapsulated in HA-PEG microbeads and sustained in vitro drug-release pattern of the DTX from the HA-PEG microbeads is observed for up to 96 h. Dual-targeted bacteriobots are prepared using CD 44 receptor-targeted HA microbeads synthesized via microfluidics, followed by the attachment of the flagellar bacterium Salmonella typhimurium, which have been genetically engineered for tumor targeting, onto the surface of the HA microbeads by the specific interaction between streptavidin on the HA beads and biotin on the bacteria. After the attachment of bacteria, the bacteriobots show an average velocity of 0.72 μm s(-1) and high chemotactic migration velocity of 0.43 μm s(-1) towards 4T1 cells lysates. CD 44 receptor-specific cellular uptake is verified through flow cytometry analysis and confocal imaging, demonstrating enhanced intracellular uptake in CD 44 receptor positive tumor cells compared to normal cells. Therefore, the present study suggests that these bacteriobots have dual-tumor-targeting abilities displaying their potential for targeted anticancer therapy.
    Full-text · Article · Nov 2015 · Advanced Healthcare Materials
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    ABSTRACT: In spite of recent significant research into various two-dimensional (2D) materials after the emergence of graphene, the development of a new 2D material that provides both high mobility and an appropriate energy band gap (which are crucial for various device applications) remains elusive. In this report, we demonstrate that the carrier transport behaviour of 2D Ti2CTx, which belongs to the family of 2D transition metal carbides and nitrides, can be tuned by modifying the surface group Tx (-OH, -F, and -O). Our results show that 2D Ti2C(OH)xFy and Ti2COx films can be obtained via simple chemical treatment, thermal annealing, and mechanical exfoliation processes. For the first time, we study the carrier transport properties of 2D Ti2CTx field effect transistors (FETs), obtaining the high field effect carrier mobilities of 10(4) cm(2) V(-1) s(-1) at room temperature. The temperature dependent resistivity of the Ti2COx film exhibits semiconductor like Arrhenius behaviour at zero gate voltage, from which we estimate the energy gap of 80 meV. One interesting feature of the FETs based on transition metal carbides is that the field effect mobility at room temperature is less sensitive to the measured transport gaps, which may arise from the dominant charge transport of activated carriers over the narrow energy gaps of the transition metal carbides. Our results open up the possibility that new 2D materials with high mobilities and appropriate band gaps can be achieved, and broaden the range of electronic device applications of Ti2CTx films.
    No preview · Article · Nov 2015 · Nanoscale
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    ABSTRACT: Carbon nanotubes (CNTs) have been investigated as field-emission sources owing to their highelectrical conductivity and high aspect ratio. However, practical applications demand that the emission lifetime of CNTs be further improved. Since ZnO demonstrates impressive electrical and thermal conductivity, when coated on the surface of CNTs, it can allow the CNT field emitters to endure high electrical stress and high temperature. Moreover, ZnO nanostructures protect the CNT emitters from being bombarded by high-energy ions, which are accelerated by the high electric field. From the result of emission lifetime measurements at the emission current density of 100 mA/cm2, we found that the emission lifetime was increased by more than a factor of 2 when ZnO had been coated onto the CNT emitters. The observation registers as an important contribution to the practical application of CNT emitters with long-term emission stability, as well as with high emission currents. In this work, we elucidate the detailed mechanism of long-term stability that can be achieved by coating ZnO nanostructures on the surface of CNTs.
    No preview · Article · Nov 2015 · Journal of Nanoscience and Nanotechnology
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    ABSTRACT: To enhance the oral bioaccessibility of flavonoids including quercetin, naringenin, and hesperetin, we prepared the edible oil-based lipid nanoparticle (LNP) system. Flavonoid-loaded LNPs were similar to the blank LNP on physicochemical characteristics (z-average < 154.8 nm; polydispersity index < 0.17; and ζ-potential < -40.8 mV), and their entrapment efficiency was > 81% at 0.3 wt% flavonoid concentration of the lipid phase. In the simulated digestion assay (mouth, stomach, and small intestine), LNPs were hydrolyzed under the small intestine condition and protected successfully incorporated flavonoids (≥ 94%). Moreover, the relative bioaccessibility of flavonoids was > 71%, which was otherwise < 15%, although flavonoids were released rapidly from LNPs into the medium. In conclusion, since the flavonoids incorporated in LNPs were preserved well during oral digestion and improved in the bioaccessibility, the designed LNP system may serve as an encapsulation strategy to enhance the bioavailability of non-bioaccessible nutraceuticals in foods.
    No preview · Article · Oct 2015 · Journal of Agricultural and Food Chemistry

  • No preview · Article · Oct 2015 · Journal of the American College of Cardiology
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    ABSTRACT: Y. J. Choi, L. Wang, and co-workers report on page 6170 a new application of an organic–inorganic hybrid perovskite (CH3NH3PbI3−xClx) in a resistive random-access-memory device. The memory device has a very simple structure consisting of Au/CH3NH3PbI3−xClx on conductive substrates, which exhibits a typical resistive-switching behavior and non-volatile properties with a low operating voltage, as well as good stability and reproducibility. This finding adds another important potential application of hybrid perovskites to their functionality library.
    No preview · Article · Oct 2015 · Advanced Materials
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    ABSTRACT: Purpose: Pegylated granulocyte-colony-stimulating factor (G-CSF) is frequently used to prevent febrile neutropenia (FN) in patients undergoing chemotherapy with a high risk of myelosuppression. This phase II/III study was conducted to determine the adequate dose of pegteograstim, a new formulation of pegylated G-CSF, and to evaluate the efficacy and safety of pegteograstim compared to pegfilgrastim. Methods: In the phase II part, 60 breast cancer patients who were undergoing DA (docetaxel and doxorubicin) or TAC (docetaxel, doxorubicin, and cyclophosphamide) chemotherapy were randomly selected to receive a single subcutaneous injection of 3.6 or 6.0 mg pegteograstim on day 2 of each chemotherapy cycle. The phase III part was seamlessly started to compare the dose of pegteograstim at selected in phase II with 6.0 mg pegfilgrastim in 117 breast cancer patients. The primary endpoint of both the phase II and III parts was the duration of grade 4 neutropenia in the chemotherapy cycle 1. Results: The mean duration of grade 4 neutropenia for the 3.6 mg pegteograstim (n = 33) was similar to that for the 6.0 mg pegteograstim (n = 26) (1.97 ± 1.79 days vs. 1.54 ± 0.95 days, p = 0.33). The 6.0 mg pegteograstim was selected to be compared with the 6.0 mg pegfilgrastim in the phase III part. In the phase III part, the primary analysis revealed that the efficacy of pegteograstim (n = 56) was non-inferior to that of pegfilgrastim (n = 59) [duration of grade 4 neutropenia, 1.64 ± 1.18 days vs. 1.80 ± 1.05 days; difference, -0.15 ± 1.11 (p = 0.36, 97.5 % confidence intervals = 0.57 and 0.26)]. The time to the absolute neutrophil count (ANC) recovery of pegteograstim (≥2000/μL) was significantly shorter than that of pegfilgrastim (8.85 ± 1.45 days vs. 9.83 ± 1.20 days, p < 0.0001). Other secondary endpoints showed no significant difference between the two groups. The safety profiles of the two groups did not differ significantly. Conclusions: Pegteograstim was shown to be as effective as pegfilgrastim in the reduction of chemotherapy-induced neutropenia in the breast cancer patients who were undergoing chemotherapy with a high risk of myelosuppression.
    No preview · Article · Oct 2015 · Supportive Care in Cancer
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    ABSTRACT: The bacteria-based microrobot (Bacteriobot) is one of the most effective vehicles for drug delivery systems. The bacteriobot consists of a microbead containing therapeutic drugs and bacteria as a sensor and an actuator that can target and guide the bacteriobot to its destination. Many researchers are developing bacteria-based microrobots and establishing the model. In spite of these efforts, a motility model for bacteriobots steered by chemotaxis remains elusive. Because bacterial movement is random and should be described using a stochastic model, bacterial response to the chemo-attractant is difficult to anticipate. In this research, we used a population-scale approach to overcome the main obstacle to the stochastic motion of single bacterium. Also known as Keller-Segel&apos;s equation in chemotaxis research, the population-scale approach is not new. It is a well-designed model derived from transport theory and adaptable to any chemotaxis experiment. In addition, we have considered the self-propelled Brownian motion of the bacteriobot in order to represent its stochastic properties. From this perspective, we have proposed a new numerical modelling method combining chemotaxis and Brownian motion to create a bacteriobot model steered by chemotaxis. To obtain modeling parameters, we executed motility analyses of microbeads and bacteriobots without chemotactic steering as well as chemotactic steering analysis of the bacteriobots. The resulting proposed model shows sound agreement with experimental data with a confidence level <0.01.
    No preview · Article · Sep 2015 · Biomicrofluidics
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    ABSTRACT: Analog memristive and memcapacitive switching characteristics were investigated in Pt-Fe2O3 core-shell nanoparticles (NPs) assembly on p+-Si substrate. The Ti/NPs/p+-Si structure exhibited gradually changing resistance (memristive) and capacitance (memcapacitive) at the same time as repeating the application of voltage with respect to the polarity of voltage. As applying negative voltage at top Ti electrode, the resistance decreased and the capacitance increased due to the increase of diffusion capacitance at n-NPs/p+ -Si junction. On the other hand, applying the positive voltage increased resistance and decreased capacitance by increasing depletion width at the junction. The polarity-dependent resistance and capacitance changes are thought to be ascribed to the charging of the NPs assembly that alters the potential of the assembly. The concurrent analog memristive and memcapacitive characteristics also emulated the biological synaptic potentiation and depression motions, which is indicative of potential application to neuromorphic devices as well as analog nonvolatile memory and circuits.
    No preview · Article · Sep 2015 · IEEE Transactions on Nanotechnology
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    ABSTRACT: We propose a new tumor-therapeutic bacteria-based microrobot (bacteriobot) combining a paclitaxel-loaded liposomal microcargo with tumor-targeting Salmonella Typhimurium bacteria. The tumor-therapeutic liposomal bacteriobot was constructed by binding biotin molecules displayed on the outer membrane proteins of the bacteria and streptavidin coated on the drug-loaded liposomes. First, we performed a motility analysis of the bacteriobot, where the bacteria-actuated liposomes showed much higher average velocity (3.09 ± 0.44 μm/s) than the liposomes without bacterial actuation (0.40 ± 0.14 μm/s). Second, we performed a cytotoxicity test using a breast cancer cell line (4T1) to check the tumor-therapeutic efficacy of the bacteriobots. The drug-loaded bacteriobots (IC50 = 16.48 ± 0.43 μg/ml) showed better tumor-killing ability than the drug-containing liposomes (IC50 = 21.91 ± 0.74 μg/ml). Moreover, the bacteriobots showed strong tumor-targeting and killing properties in a simple co-culture chamber containing normal cells (NIH/3T3) and cancer cells (4T1). These results revealed that the constructed bacteriobots can be used for active tumor therapy.
    Full-text · Article · Sep 2015 · Sensors and Actuators B Chemical
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    ABSTRACT: The CH3 NH3 PbI3- x Clx organic-inorganic hybrid perovskite material demonstrates remarkable resistive switching behavior, which can be applicable in resistive random access memory devices. The simply designed Au/CH3 NH3 PbI3- x Clx /FTO structure is fabricated by a low-temperature, solution-processable method, which exhibits remarkable bipolar resistive switching and nonvolatile properties. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
    Full-text · Article · Aug 2015 · Advanced Materials
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    ABSTRACT: We report the preparation of thickness-controlled few-layer black phosphorus (BP) films through the modulated plasma treatment of BP flakes. Not only does the plasma treatment control the thickness of the BP film, it also removes the chemical degradation of the exposed oxidized BP surface, which results in enhanced field-effect transistor (FET) performance. Our fabricated BP FETs were passivated with polymethyl methacrylate (PMMA) immediately after the plasma etching process. With these techniques, a high field-effect mobility was achieved, 1150 cm2/Vs, with an Ion/Ioff ratio of ~100,000 at room temperature. Furthermore, a fabricated FET with plasma-treated few-layer BP that was passivated with PMMA was found to retain its I-V characteristics and thus to exhibit excellent environmental stability over several weeks.
    No preview · Article · Aug 2015 · ACS Nano

  • No preview · Conference Paper · Aug 2015

  • No preview · Conference Paper · Aug 2015
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    ABSTRACT: Palonosetron is the second-generation 5-hydroxytryptamine 3 receptor antagonist (5-HT3RA) that has shown better efficacy than the first-generation 5-HT3RA for prevention of chemotherapy-induced nausea and vomiting (CINV) in patients receiving moderately emetogenic chemotherapy (MEC). Granisetron transdermal delivery system (GTDS), a novel transdermal formulation, was developed to deliver granisetron continuously over 7 days. This study compared the efficacy and tolerability of the GTDS to palonosetron for the control of CINV following MEC. A total of 196 patients were randomized to GP or PG group. In this multicenter, randomized, open-label, cross-over, active-controlled, Phase IV study, GP group was assigned to receive transdermal granisetron (one GTDS patch, 7 days) in the first chemotherapy cycle, palonosetron (iv 0.25 mg/day, 1 days) in the second chemotherapy cycle before receiving MEC, and PG group was assigned to receive palonosetron in the first cycle and GTDS in the second cycle. Primary endpoint was the percentage of chemotherapy cycles achieving complete response (CR; defined as no emetic episodes and no rescue medication use) during the acute phase (0-24 h in post-chemotherapy; non-inferiority comparison with palonosetron). Total 333 cycles (165 in GTDS and 168 in palonosetron) were included in the per protocol analysis. The GTDS cycles showed non-inferiority to palonosetron cycles during the acute phase: CR was achieved by 124 (75.2 %) patients in the GTDS cycles and 134 (79.8 %) patients in the palonosetron cycles (treatment difference, -4.6 %; 95 % confidence interval, -13.6-4.4). There was no significant difference in CR rate during acute phase after the end of the first and second chemotherapy cycle between GP and PG group (p = 0.405, p = 0.074). Patients' satisfaction, assessed using Functional Living Index-Emesis (FLI-E), GTDS cycle were higher than those of palonosetron cycle in GP group (FLI-E score; median 1549.5 in GTDS cycle, median 1670.0 in palonosetron cycle). Both treatments were well tolerated and safe. Transdermal granisetron is a good alternative therapeutic option to palonosetron for preventing CINV after MEC.
    No preview · Article · Aug 2015 · Supportive Care in Cancer
  • Youngje Jo · Seokwon Lim · Pahn-Shick Chang · Young Jin Choi
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    ABSTRACT: Isoquercitrin is a phenolic compound well-known for having greater health benefits than quercitin, its aglycone derivative, and other related glycosides. However, isoquercitrin is rarely found in nature. Here, we optimized the conditions for the enzymatic transformation of isoquercitrin from rutin that was extracted from jujube leaf using the hesperidinase, enzyme complex containing β-d-glucosidase and α-l-rhamnosidase. The maximum productivity (2.57 ± 0.16 mg/mL) was experimentally found under the following conditions: 47.3 °C, 52.16 h, and pH 5.31, which agreed well with the predicted value (2.65 mg/mL). However, the achievement of this maximum yield was due to the absence of β-d-glucosidase activity. Further investigations using a β-d-glucosidase assay and reaction measurements under various conditions revealed that the β-d-glucosidase activity was not blocked by denaturation or known inhibitory factors. Currently, there are no recognized β-d-glucosidase inhibitors present in the jujube leaf; however, our observations strongly suggest that an unidentified β-d-glucosidase inhibitor exists in jujube leaf extract.
    No preview · Article · Aug 2015 · Food Chemistry
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    ABSTRACT: Tumor hypoxia is significant in promoting tumor progression and resistance to therapy, and hypoxia-inducible factor 1α (HIF-1α) is essential in the adaptive response of cells to hypoxia. The aim of the present study was to investigate the expression of hypoxic markers and evaluate their prognostic significance in soft tissue sarcoma (STS). A retrospective analysis of 55 patients with STS from Pusan National University Hospital (Busan, Korea) between 1998 and 2007 was conducted, using immunohistochemistry to analyze the expression of HIF-1α, carbonic anhydrase 9 (CA9), glucose transporter-1 (GLUT1) and vascular endothelial growth factor (VEGF). The association between the overexpression of these markers and clinicopathological characteristics, including the overall survival (OS) and progression-free survival (PFS) in cases of STS, were investigated. Overexpression of HIF-1α, CA9, GLUT1 and VEGF was shown in 54.5, 32.7, 52.7 and 25.5% of tumors, respectively, and all exhibited a significant association with high French Federation of Cancer Centers (FNCLCC) grade and high American Joint Committee on Cancer (AJCC) stage. Overexpression of HIF-1α and CA9 was associated with a shorter OS and a shorter PFS. On multivariate analysis, AJCC stage and HIF-1α overexpression had independent prognostic significance. In the group receiving chemotherapy (n=27), HIF-1α overexpression was independently associated with a decreased OS. These results indicate that overexpression of HIF-1α and CA9 is associated with poor prognosis, and that HIF-1α overexpression is an independent unfavorable prognostic factor in STS.
    Preview · Article · Apr 2015 · Oncology letters

Publication Stats

2k Citations
530.36 Total Impact Points


  • 2015-2016
    • Sejong University
      Sŏul, Seoul, South Korea
  • 2014-2015
    • Chonnam National University
      • School of Mechanical Systems Engineering
      Gwangju, Gwangju, South Korea
  • 2013-2015
    • Sejong General Hospital
      Bucheon, Gyeonggi-do, South Korea
  • 2006-2015
    • Myongji University
      • Department of Physics
      Sŏul, Seoul, South Korea
    • Ajou University
      • Department of Physics
      Sŏul, Seoul, South Korea
  • 1998-2015
    • Pusan National University
      • • Department of Internal Medicine
      • • Department of Polymer Science and Engineering
      Busan, Busan, South Korea
  • 1997-2015
    • Seoul National University
      • • Department of Agricultural Biotechnology
      • • College of Agriculture and Life Sciences
      • • Department of Electrical and Computer Engineering
      • • Inter-University Semiconductor Research Center
      Sŏul, Seoul, South Korea
  • 2008-2013
    • Catholic University of Korea
      • College of Medicine
      Sŏul, Seoul, South Korea
    • University of Cambridge
      • Department of Engineering
      Cambridge, England, United Kingdom
    • University of Texas Southwestern Medical Center
      • Department of Physiology
      Dallas, Texas, United States
    • Chonbuk National University
      • Semiconductor Physics Research Center
      Sŏul, Seoul, South Korea
  • 1998-2013
    • Kyung Hee University
      • • College of Oriental Medicine
      • • Department of Physics
      Sŏul, Seoul, South Korea
  • 2000-2012
    • Hallym University
      • College of Medicine
      Sŏul, Seoul, South Korea
    • University of Ulsan
      Ulsan, Ulsan, South Korea
  • 2011
    • Gyeongsang National University
      • School of Materials Science and Engineering
      Shinshū, Gyeongsangnam-do, South Korea
  • 2009-2011
    • Chungbuk National University
      • College of Veterinary Medicine
      Chinsen, North Chungcheong, South Korea
    • Sogang University
      • Department of Chemical and Biomolecular Engineering
      Seoul, Seoul, South Korea
  • 2007-2011
    • Hallym University Medical Center
      • Department of Internal Medicine
      Sŏul, Seoul, South Korea
    • Washington State University
      • School of Mechanical and Materials Engineering
      پولمن، واشینگتن, Washington, United States
    • Samsung Medical Center
      • Division of Breast and Endocrine Surgery
      Sŏul, Seoul, South Korea
  • 2004-2011
    • Chungnam National University
      • • College of Medicine
      • • Department of Mechanical Design Engineering
      Daiden, Daejeon, South Korea
    • Korea Institute of Science and Technology
      • Interaction and Robotics Research Center
      Seoul, Seoul, South Korea
  • 2010
    • Taihan Electric Wire
      안양시, Gyeonggi-do, South Korea
    • Dong-A University
      Tsau-liang-hai, Busan, South Korea
    • Eulji University
      Daiden, Daejeon, South Korea
  • 2006-2008
    • Sungkyunkwan University
      Sŏul, Seoul, South Korea
  • 2001-2008
    • University of Seoul
      Sŏul, Seoul, South Korea
  • 2005-2006
    • University of California, Davis
      • Department of Food Science and Technology
      Davis, California, United States