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Open Access Publications from the University of California

Scholarly Works (12 results)

  • Thesis
  • Peer Reviewed
UC Berkeley Electronic Theses and Dissertations (2022)

Electricity is indispensable in our daily life and batteries are the widely used energy sources for portable devices in the modern world. However, harmful chemicals and wastes in batteries can lead to serious environmental and health problems without proper dispositions. As such, renewable energy sources such as solar cells have drawn lots of interests with great progresses in recent years. In this work, two forms of renewable energy harvesters based on polymers are studied based on moistures and thermal gradients in the environment. Material properties, fundamental operation mechanisms, and application demonstrations of these two renewable energy harvesters are investigated in the dissertation.

The moisture-based electric generators have long working time and high energy density output by utilizing the mechanism of the proton transportation and proton concentration oscillation. The specific polymer used in the generator has a moisture-induced oscillation surface potential from the functional groups of the polymer. Both dynamic simulation and oscillation theory have been developed to analyze this phenomenon. The self-oscillation behavior help extending the operation period of the energy harvester under the constant feeding of moistures. Experimental results show the short-circuit current density can reach 1.5 μA/cm2 and a maximum open-circuit voltage of 0.4 V with a long operation period up to 15,000 seconds with an energy density of 16.8 mJ/cm2.

The thermoelectric energy harvester has an ultra-high Seebeck coefficient and self-healing properties, which is suitable for harvesting energy from temperature gradients such as wearable devices between the human skin and the environment. The energy generator is based on the material of ionogel, which has different pore sizes and polarities to results in the very different diffusion coefficients of anions and cations. Specifically, the diffusion coefficients are characterized and simulated by using the molecular dynamic simulation under different temperatures and tested experimentally. The whole device has a measured Seebeck coefficient at 298 μV/K, which is generally higher than those of traditional thermoelectric materials. Furthermore, the prototype device is flexible, bendable and self-healable for potential applications in harvesting electrical energy for wearable devices.

    Cover page: Renewable Polymeric Energy Harvesters from Moisture and Heat
    • Article
    • Peer Reviewed
    UC Davis Previously Published Works (2024)

    Background

    Acute kidney injury (AKI) is a common complication after surgery and is associated with detrimental outcomes. This systematic review and meta-analysis evaluated perioperative dexmedetomidine on AKI and renal function after non-cardiac surgery.

    Methods

    PubMed, Embase, and Cochrane Library databases were searched until August 2023 for randomised trials comparing dexmedetomidine with normal saline on AKI and renal function in adults undergoing non-cardiac surgery. The primary outcome was the incidence of AKI (according to Kidney Disease Improving Global Outcomes or Acute Kidney Injury Network criteria). Meta-analysis was performed using a random-effect model. We conducted sensitivity analysis, trial sequential analysis (TSA), and Grading of Recommendations Assessment, Development and Evaluation level of evidence.

    Results

    Twenty-three trials involving 2440 patients were included. Dexmedetomidine administration, as compared to normal saline, significantly reduced the incidence of AKI (7.4% vs. 13.2%; risk ratio = 0.57, 95% CI = 0.40 to 0.83, P =  0.003, I2 = 0%; a high level of evidence); TSA and sensitivity analyses suggested the robustness of this outcome. For the renal function and inflammation parameters, dexmedetomidine decreased serum creatinine, blood urea nitrogen, cystatin C, tumour necrosis factor-α, and interleukin-6, and increased urine output and estimated glomerular filtration rate. Additionally, dexmedetomidine reduced postoperative nausea and vomiting and length of hospital stay. Dexmedetomidine was associated with an increased rate of bradycardia, but not hypotension.

    Conclusion

    Dexmedetomidine administration reduced the incidence of AKI and improved renal function after non-cardiac surgery. Based on a high level of evidence, dexmedetomidine is recommended as a component of perioperative renoprotection.

    Registration

    International Prospective Register of Systematic Reviews; Registration number: CRD42022299252.
      Cover page: Dexmedetomidine and acute kidney injury after non-cardiac surgery: a meta-analysis with trial sequential analysisCreative Commons 'BY' version 4.0 license
      • Article
      • Peer Reviewed
      UC Davis Previously Published Works (2021)

      Purpose

      Patients undergoing major laparoscopic surgery often experience significant pain and postoperative nausea and vomiting (PONV). Deep neuromuscular block (NMB) improves surgical conditions and facilitates the application of low intra-abdominal pressure (IAP), which may be beneficial for these patients. This study is designed to determine the effects of deep NMB combined with low IAP, as compared to moderate NMB combined with standard IAP, on patients' nociceptive recovery after major laparoscopic gastrointestinal surgery.

      Study design and methods

      This single-center randomized controlled trial will include 220 patients scheduled for major laparoscopic gastrointestinal surgery (lasts for ≥ 90 minutes). Patients will be randomly assigned, with a 1:1 ratio, into a deep NMB + low IAP group (train of four = 0, post-tetanic count = 1-3, IAP = 8 mmHg) and a moderate NMB + standard IAP group (train of four = 1-3, IAP = 12 mmHg). If the surgical workspace is inadequate, the surgeons can request a step increase of 1 mmHg in IAP during 3-min intervals. The upper limit of IAP will be set at 15 mmHg. Postoperative recovery will be assessed using the postoperative quality recovery scale (PQRS). The primary outcome of this trial is the PQRS nociceptive recovery (including pain and PONV) at postoperative day (POD) 1. The secondary outcomes include recovery in other PQRS domains at POD 1, and recovery in all PQRS domains in a post-anesthesia care unit, at POD 3 in the surgical wards, at hospital discharge, and at postoperative 30 days. For the sample size estimation, 110 patients in each group (220 in total) would be needed to detect an absolute increase rate of 20% in the PQRS nociceptive domain in the deep NMB + low IAP group at POD 1.

      Discussion

      This study investigates the effects of deep NMB combined with low IAP on postoperative PQRS nociceptive recovery in patients undergoing major laparoscopic gastrointestinal surgery. We expect that this deep NMB + low IAP strategy would improve postoperative pain and PONV following major laparoscopic gastrointestinal surgery.
        Cover page: Deep Neuromuscular Blockade Combined with Low Pneumoperitoneum Pressure for Nociceptive Recovery After Major Laparoscopic Gastrointestinal Surgery: Study Protocol for a Randomized Controlled Trial
        • Article
        • Peer Reviewed
        UC Davis Previously Published Works (2023)

        Background

        Postoperative nausea and vomiting (PONV) are common after general anesthesia and surgery. This study aims to compare the effects of total intravenous opioid-free anesthesia (OFA) with conventional opioid-based anesthesia (OBA) on PONV in patients following treatments for wounds of lower extremities.

        Methods

        This randomized, double-blind, crossover trial will include a total of 72 adult patients scheduled for at least two separate surgical treatments of lower extremity wounds under general anesthesia. Patients will be randomized to 1 of 2 anesthesia sequences of OFA and OBA. Patients in sequence 1 will receive OFA in the first treatment procedure and OBA in the second procedure, while patients in sequence 2 will receive the two anesthesia regimens in the reverse order. The washout period is at least 5 days. OFA will be delivered with intravenous esketamine, lidocaine, dexmedetomidine, and propofol. OBA will be delivered with intravenous sufentanil and propofol. The primary endpoint is the incidence of PONV within the first 48 h postoperatively. The secondary endpoints are the severity of PONV, antiemetic rescue therapy, postoperative pain scores, the worst pain, need for rescue analgesia, postoperative sedation, hypotension, bradycardia, hypertension, tachycardia, hypoxemia, psychotomimetic or dissociative effects, time to extubation, and length of postanesthesia care unit stay. Patients who complete two surgical procedures with designated anesthesia regimens will be included in the final analyses.

        Discussion

        This crossover trial will determine whether total intravenous OFA reduces PONV in patients following treatments for lower extremity wounds. The results of this trial will also represent an important step to understand the benefits and possible risks of OFA in surgical patients.

        Trial registration

        Chinese Clinical Trial Registry (ChiCTR2200061511).
          Cover page: Effects of opioid-free total intravenous anesthesia on postoperative nausea and vomiting after treatments of lower extremity wounds: protocol for a randomized double-blind crossover trialCreative Commons 'BY' version 4.0 license
          • Article
          • Peer Reviewed
          UC Davis Previously Published Works (2022)
          Background: Same-day esophagogastroduodenoscopy and colonoscopy procedures under sedation have been increasingly performed. This study aims to assess the effects of esketamine combined with ciprofol (a novel anesthetic/sedative agent) or propofol on respiratory and hemodynamic adverse events in patients undergoing same-day bidirectional endoscopy. Methods: This is a prospective, randomized, double-blind, placebo-controlled, 2 × 2 factorial trial. A total of 180 adult patients scheduled for same-day bidirectional endoscopy under sedation will be randomized, in a 1:1:1:1 ratio, to receive 1 of 4 sedation regimens: 1) ciprofol and esketamine, 2) propofol and esketamine, 3) ciprofol and normal saline placebo, or 4) propofol and normal saline placebo. The primary outcome is a composite of desaturation [peripheral oxygen saturation (SpO2) < 95%] and hypotension [mean blood pressure (MBP) < 65 mmHg or decrease in MBP ≥20% of baseline] during the sedation and in the recovery room. Secondary outcomes include episodes of desaturation, severe desaturation (SpO2 < 90%), hypotension, severe hypotension (decrease in MBP ≥30% of baseline), bradycardia, postoperative nausea and vomiting, dizziness or headache, hallucination or nightmare, injection pain, pain scores and fatigue scores, endoscopist satisfaction, and patient satisfaction. Data will be analyzed on the modified intention-to-treat basis. Discussion: We hypothesize that esketamine as an adjuvant to ciprofol or propofol sedation would improve cardiorespiratory stability. In addition, the potential interactions between interventions will be explored using the factorial design. The results of this trial will provide evidence for daily practice of sedation regimens for same-day bidirectional endoscopy. Clinical Trial Registration: Chinese Clinical Trials Registry, Identifier ChiCTR2100052523.
            Cover page: Esketamine as an Adjuvant to Ciprofol or Propofol Sedation for Same-Day Bidirectional Endoscopy: Protocol for a Randomized, Double-Blind, Controlled Trial With Factorial Design
            • Article
            • Peer Reviewed
            UC Davis Previously Published Works (2022)

            Background

            Opioid-free anesthesia (OFA) may improve postoperative outcomes by reducing opioid-related adverse effects. This study aims to evaluate the effects of OFA on postoperative nausea and vomiting (PONV), postoperative pain, and 30-day outcomes after thyroid and parathyroid surgery.

            Methods

            This two-center, randomized, double-blind, controlled trial will include 400 adult patients scheduled for thyroid and parathyroid surgery. Patients will be randomly assigned, 1:1 and stratified by sex and site, to an OFA group (esketamine, lidocaine, and dexmedetomidine) or a control group (opioid-based anesthesia with sufentanil). All patients will receive propofol-based total intravenous anesthesia and PONV prophylaxis with dexamethasone and ondansetron. The primary outcome is the incidence of PONV (defined as experiencing any event of nausea, retching, or vomiting) during the first 48 h postoperatively. The secondary outcomes include the severity of PONV, antiemetic rescue therapy, pain scores at rest and while coughing, need for rescue analgesia, perioperative adverse effects related to anesthetics or analgesics (hypotension, bradycardia, hypertension, tachycardia, desaturation, dizziness, headache, hallucination, and nightmare), time to extubation, length of post-anesthesia care unit stay, length of postoperative hospital stay, patient satisfaction, and a composite of 30-day major adverse events (myocardial infarction, cardiac arrest, cerebrovascular accident, coma, acute renal failure, pulmonary embolism, sepsis, septic shock, deep neck space infection, reintubation, reoperation, blood transfusion, failure to wean off ventilator, and death). Analyses will be performed in the modified intention-to-treat population.

            Discussion

            We hypothesize that our OFA regimen reduces PONV after thyroid and parathyroid surgery. We will also investigate whether OFA leads to improvements in postoperative pain and major adverse events. Our results will offer evidence for optimizing anesthesia regimens in patients who undergo thyroid and parathyroid surgical procedures.

            Clinical trial registration

            http://www.chictr.org.cn, identifier: ChiCTR2200059656.
              Cover page: Opioid-free total intravenous anesthesia for thyroid and parathyroid surgery: Protocol for a randomized, double-blind, controlled trial
              • Article
              • Peer Reviewed
              UC Davis Previously Published Works (2022)

              Background

              Results from previous studies evaluating the effects of remote ischemic preconditioning (RIPC) on morbidity and mortality after cardiac surgery are inconsistent. This meta-analysis of randomized controlled trials (RCTs) aims to determine whether RIPC improves cardiac and renal outcomes in adults undergoing cardiac surgery.

              Methods

              PubMed, EMBASE, and Cochrane Library were comprehensively searched to identify RCTs comparing RIPC with control in cardiac surgery. The coprimary outcomes were the incidence of postoperative myocardial infarction (MI) and the incidence of postoperative acute kidney injury (AKI). Meta-analyses were performed using a random-effect model. Subgroup analyses were conducted according to volatile only anesthesia versus propofol anesthesia with or without volatiles, high-risk patients versus non-high-risk patients, and Acute Kidney Injury Network (AKIN) or Kidney Disease Improving Global Outcomes (KDIGO) criteria versus other criteria for AKI diagnosis.

              Results

              A total of 79 RCTs with 10,814 patients were included. While the incidence of postoperative MI did not differ between the RIPC and control groups (8.2% vs 9.7%; risk ratio [RR] = 0.87, 95% confidence interval [CI], 0.76-1.01, P = .07, I2 = 0%), RIPC significantly reduced the incidence of postoperative AKI (22% vs 24.4%; RR = 0.86, 95% CI, 0.77-0.97, P = .01, I2 = 34%). The subgroup analyses showed that RIPC was associated with a reduced incidence of MI in non-high-risk patients, and that RIPC was associated with a reduced incidence of AKI in volatile only anesthesia, in non-high-risk patients, and in the studies using AKIN or KDIGO criteria for AKI diagnosis.

              Conclusions

              This meta-analysis demonstrates that RIPC reduces the incidence of AKI after cardiac surgery. This renoprotective effect of RIPC is mainly evident during volatile only anesthesia, in non-high-risk patients, and when AKIN or KDIGO criteria used for AKI diagnosis.
                Cover page: Remote Ischemic Preconditioning Reduces Acute Kidney Injury After Cardiac Surgery: A Systematic Review and Meta-analysis of Randomized Controlled Trials
                • Article
                • Peer Reviewed
                UC Berkeley Previously Published Works (2021)
                A variety of autonomous oscillations in nature such as heartbeats and some biochemical reactions have been widely studied and utilized for applications in the fields of bioscience and engineering. Here, we report a unique phenomenon of moisture-induced electrical potential oscillations on polymers, poly([2-(methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide-co-acrylic acid), during the diffusion of water molecules. Chemical reactions are modeled by kinetic simulations while system dynamic equations and the stability matrix are analyzed to show the chaotic nature of the system which oscillates with hidden attractors to induce the autonomous surface potential oscillation. Using moisture in the ambient environment as the activation source, this self-excited chemoelectrical reaction could have broad influences and usages in surface-reaction based devices and systems. As a proof-of-concept demonstration, an energy harvester is constructed and achieved the continuous energy production for more than 15,000 seconds with an energy density of 16.8 mJ/cm2. A 2-Volts output voltage has been produced to power a liquid crystal display toward practical applications with five energy harvesters connected in series.
                  Cover page: Moisture-induced autonomous surface potential oscillations for energy harvesting
                  • Article
                  • Peer Reviewed
                  UC Davis Previously Published Works (2022)
                  Background: The mechanisms underlying myocardial ischemia/reperfusion (I/R) injury are not fully understood. This study aims to explore key candidate genes and potential therapeutic targets for treatment of myocardial I/R injury. Methods: The transcriptional profiles of ventricular myocardium during cardiac arrest, ischemia, and reperfusion were obtained from the Gene Expression Omnibus database. Based on the transcriptional data of GSE6381, functional pathway and process enrichment analyses, protein-protein interaction network, and gene set enrichment analyses were conducted. In the animal experiments, we established the myocardial I/R injury model in mice. We validated the mRNA and protein expression of the key genes using the qPCR and western blots. We further assessed the expression and localization of CCL21 and its receptors using immunofluorescence staining experiments. Results: The microarray analyses identified five key genes (CCL21, XCR1, CXCL13, EDN1, and CASR). Myocardial I/R process in mice resulted in significant myocardial infraction, histological damage, and myocardial apoptosis. The results of qPCR and western blots showed that the expression of CCL21 and CXCL13 were increased following myocardial I/R injury in mice. Furthermore, the immunofluorescence staining results revealed that the expression of GPR174/CCR7 (CCL21 receptors), but not CXCR5 (CXCL13 receptor), was elevated following myocardial I/R injury. Moreover, the activated CCL21-GPR174/CCR7 signaling was located on the cardiac fibroblasts of the myocardium with I/R injury. Conclusion: This study revealed several key factors underlying myocardial I/R injury. Of these, the activation of CCL21-GPR174/CCR7 signaling on cardiac fibroblasts was highlighted, which provides potential therapeutic targets for cardioprotection.
                    Cover page: Activation of CCL21-GPR174/CCR7 on cardiac fibroblasts underlies myocardial ischemia/reperfusion injury
                    • Article
                    • Peer Reviewed
                    UC Davis Previously Published Works (2023)

                    Background

                    Depressive symptoms are common among patients with lung cancer. We aimed to assess the effects of esketamine on postoperative depressive symptoms after thoracoscopic lung cancer surgery.

                    Methods

                    In this randomized, double-blind, placebo-controlled trial, 156 patients undergoing thoracoscopic lung cancer surgery were randomly allocated in a 1:1 ratio to receive intravenous esketamine (intraoperatively and in patient-controlled analgesia until 48 h postoperatively) or normal saline placebo. The primary outcome was the proportion of patients with depressive symptoms at 1 month postoperatively, assessed using the Beck Depression Inventory-II (BDI-II). Secondary outcomes included depressive symptoms at 48 h postoperatively, hospital discharge and 3 months postoperatively, BDI-II scores, anxious symptoms, Beck Anxiety Inventory scores, Quality of Recovery-15 (QoR-15) scores, and 1- and 3-month mortality.

                    Main results

                    A total of 151 patients (75 in the esketamine group and 76 in the normal saline group) completed the 1-month follow-up. The esketamine group had a significantly lower incidence of depressive symptoms at 1 month compared to the normal saline group (1.3% vs. 11.8%; risk difference = -10.5, 95%CI = -19.6% to -0.49%; p = 0.018). After excluding patients without lung cancer diagnosis, the incidence of depressive symptoms was also lower in the esketamine group (1.4% vs. 12.2%; risk difference = -10.8, 95%CI = -20.2% to -0.52%; p = 0.018). The secondary outcomes were similar between groups, except that the esketamine group had higher QoR-15 scores at 1 month postoperatively (median difference = 2; 95%CI = 0 to 5; p = 0.048). The independent risk factors for depressive symptoms were hypertension (odds ratio = 6.75, 95%CI = 1.13 to 40.31; p = 0.036) and preoperative anxious symptoms (odds ratio = 23.83, 95%CI = 3.41 to 166.33; p = 0.001).

                    Conclusion

                    Perioperative administration of esketamine reduced the incidence of depressive symptoms at 1 month after thoracoscopic lung cancer surgery. History of hypertension and preoperative anxious symptoms were independent risk factors for depressive symptoms.Clinical trial registration: Chinese Clinical Trial Registry http://www.chictr.org.cn, Identifier (ChiCTR2100046194).
                      Cover page: Effect of esketamine on postoperative depressive symptoms in patients undergoing thoracoscopic lung cancer surgery: A randomized controlled trialCreative Commons 'BY-ND' version 4.0 license
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