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1.
J Nerv Ment Dis ; 2020 May 19.
Artigo em Inglês | MEDLINE | ID: mdl-32433202

RESUMO

The study recruited 168 patients diagnosed with major depressive disorder (MDD). The nine-item Patient Health Questionnaire (PHQ-9) and Perceived Deficits Questionnaire for Depression (PDQ-D) were lower and the Digit Symbol Substitution Test (DSST) was higher in the community volunteers than those in MDD patients. Depression-related scores (17-item Hamilton Depression Rating Scale [HAMD-17], Clinical Global Impressions-Severity of Illness Scale [CGI-S], and PHQ-9), functioning-related scores (Sheehan Disability Scale [SDS]), and Work Efficiency and Activity Damage-Specific Health Problems questionnaire work productivity loss were decreased, and the quality of life-related scores (European Quality of life-5 Dimensions [EQ-5D] utility score) were increased in the MDD patients. PDQ-D was decreased and DSST was increased with the increase of follow-up time. Linear regression indicated that cognitive symptoms (PDQ-D and DSST) improved more slowly than depressive symptoms (PHQ-9). At baseline, PDQ-D was related with functioning (SDS and work productivity loss). PDQ-D and DSST were related with EQ-5D utility score. In addition, at month 6, PDQ-D was related with functioning (SDS and work productivity loss) and EQ-5D utility score. Cognitive impairment might be a risk for MDD and MDD-related changes in the functioning and quality of life.

2.
J Clin Oncol ; : JCO1902104, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32401634

RESUMO

PURPOSE: Axicabtagene ciloleucel (axi-cel) is an autologous CD19-directed chimeric antigen receptor (CAR) T-cell therapy approved for relapsed/refractory large B-cell lymphoma (LBCL) on the basis of the single-arm phase II ZUMA-1 trial, which showed best overall and complete response rates in infused patients of 83% and 58%, respectively. We report clinical outcomes with axi-cel in the standard-of-care (SOC) setting for the approved indication. PATIENTS AND METHODS: Data were collected retrospectively from all patients with relapsed/refractory LBCL who underwent leukapheresis as of September 30, 2018, at 17 US institutions with the intent to receive SOC axi-cel. Toxicities were graded and managed according to each institution's guidelines. Responses were assessed as per Lugano 2014 classification. RESULTS: Of 298 patients who underwent leukapheresis, 275 (92%) received axi-cel therapy. Compared with the registrational ZUMA-1 trial, 129 patients (43%) in this SOC study would not have met ZUMA-1 eligibility criteria because of comorbidities at the time of leukapheresis. Among the axi-cel-treated patients, grade ≥ 3 cytokine release syndrome and neurotoxicity occurred in 7% and 31%, respectively. Nonrelapse mortality was 4.4%. Best overall and complete response rates in infused patients were 82% (95% CI, 77% to 86%) and 64% (95% CI, 58% to 69%), respectively. At a median follow-up of 12.9 months from the time of CAR T-cell infusion, median progression-free survival was 8.3 months (95% CI, 6.0 to15.1 months), and median overall survival was not reached. Patients with poor Eastern Cooperative Oncology Group performance status of 2-4 and elevated lactate dehydrogenase had shorter progression-free and overall survival on univariable and multivariable analysis. CONCLUSION: The safety and efficacy of axi-cel in the SOC setting in patients with relapsed/refractory LBCL was comparable to the registrational ZUMA-1 trial.

3.
Anal Chem ; 2020 May 26.
Artigo em Inglês | MEDLINE | ID: mdl-32456414

RESUMO

Fatty acid amide hydrolase (FAAH) is an important drug target for the treatment of many disease related conditions such as pain, inflammation and mood disorders due to its vital role in the metabolism of endocannabinoids. In our present work, a FAAH-activated fluorescent probe named THPO was developed which has high selectivity and excellent sensitivity for FAAH in complex systems. Critically, its metabolite AHPO has long excitation and emission wavelengths and high fluorescence quantum yield which are necessary for monitoring the activity of FAAH in living systems. In addition, a visual high-throughput screening method for FAAH inhibitors was established using THPO which resulted in the discovery of an efficient natural inhibitor Neobavaisoflavone that was identified from 68 traditional herbal medicines. Our results indicate that THPO can be used as a molecular tool for the rapid evaluation of FAAH activity in complex systems as well as providing an effective approach to screen FAAH inhibitors providing a boost for the discovery of therapeutic agents toward FAAH related diseases.

4.
Langmuir ; 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32460493

RESUMO

Enzymes are an important class of biomacromolecules which catalyze many metabolic processes in living systems. Nanomaterials can be synthesized with tailored sizes as well as desired surface modifications, thus well acting as promising enzyme regulators. Fluorescent gold nanoclusters (AuNCs) are a representative class of ultrasmall nanoparticles (USNPs) with sizes of ~ 2 nm, smaller than most of proteins including enzymes. In this work, we chose α-chymotrypsin (ChT) and AuNCs as the model system. Activity assays and inhibition kinetics studies showed that dihydrolipoic acid (DHLA)-coated AuNCs (DHLA-AuNCs) had a high inhibitory potency (IC50 = 3.4 µM) and high inhibitory efficacy (> 80%) on ChT activity through non-competitive inhibition mechanism. In distinct contrast, glutathione (GSH)-coated AuNCs (GSH-AuNCs) had no significant inhibition effects. Fluorescence spectroscopy, agarose gel electrophoresis and circular dichroism (CD) spectroscopy were conducted to explore the underlying mechanisms. A two-step interaction model was proposed. First, both DHLA-AuNCs and GSH-AuNCs might be bound to the positively charged sites of ChT through electrostatic forces. Second, further hydrophobic interactions occurred between three tyrosine residues of ChT and the hydrophobic carbon chain of DHLA, leading to a significant structural change thus to deactivate ChT on the allosteric site. On the contrary, no such interactions occurred with GSH of zwitterionic characteristic, which explained no inhibitory effect of GSH-AuNCs on ChT. To the best of our knowledge, this is the first example of the allosteric inhibition of ChT by nano regulators. These findings provide a fundamental basis for the design and development of nano regulators.

6.
BMJ Open ; 10(5): e035003, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-32371513

RESUMO

INTRODUCTION: Ageing is associated with a multitude of healthcare issues including dementia, depression, frailty, morbidity associated with chronic disease and high healthcare utilisation. With Singapore's population projected to age significantly over the next two decades, it has become increasingly important to understand the disease burden and etiological process among older adults. The Community Health and Intergenerational study aims to holistically examine ageing in place by investigating the resilience and vulnerability factors of the ageing process in the biological, psychological and social domains within the environment. METHODS AND ANALYSIS: Using a cohort multiple randomised controlled trial design, comprehensive health profiles of community-dwelling older adults will be collected. The objective is to recruit 1000 participants (aged 60-99 years) living in the western region of Singapore within a period of 3 years (2018-2020). Assessments include basic sociodemographic, physical health and function (cardiac, oral and blood profiles and visual function), cognitive functioning, daily functioning, physical fitness, emotional state, free-flowing speech, sleep quality, social connectedness, caregiver burden, intergenerational communication, quality of life, life satisfaction, attitudes to ageing and gratitude and compassion. Results from the cohort will enable future studies to identify at-risk groups and develop interventions to improve the physical and mental health and quality of life of older adults. ETHICS AND DISSEMINATION: Approval of the cohort study by the National University of Singapore Institutional Review Board (NUS-IRB Reference code: H-17-047) was obtained on 12 October 2017. Written consent will be obtained from all participants. Findings from the cohort study will be disseminated by publication of peer-reviewed manuscripts, presentations at scientific meetings and conferences with local stakeholders.

7.
Artigo em Inglês | MEDLINE | ID: mdl-32374583

RESUMO

In this work, we prepared flexible carbon-fiber/semimetal Bi nanosheet arrays from solvothermal-synthesized carbon-fiber/Bi2O2CO3 nanosheet arrays via a reductive calcination process. The flexible carbon-fiber/semimetal Bi nanosheet arrays can function as photocatalysts and photoelectrocatalysts for 2,4-dinitorphenol oxidation. Compared with carbon-fiber/Bi2O2CO3 nanosheet arrays, the newly designed flexible carbon-fiber/semimetal Bi nanosheet arrays show enhanced ultraviolet-visible (UV-vis) light absorption efficiency and photocurrent, photocatalytic, and photoelectrocatalytic activities. Photocatalytic analyses indicate that the surface plasmon resonance (SPR) of semimetal Bi occurs under solar-simulated light irradiation during the photocatalytic process. The carbon-fiber traps the hot electrons exerted from the SPR of semimetal Bi and creates holes in the semimetal Bi nanosheets, which boosts the photocatalytic activity of the carbon fiber through plasmonic sensitization. Both photocatalytic experiments and density functional theory (DFT) calculations indicate that the electrons transferred to the carbon fiber and the holes created in semimetal Bi contribute to the formation of •O2- and •OH, respectively. The synergistic effect between electrocatalysis and photocatalysis under the solar-simulated light results in almost complete degradation of 2,4-dinitorphenol during the photoelectrocatalytic process. This work realizes a non-noble-metal plasmonic catalyst and provides a new avenue for the commercialization of photocatalysis and photoelectrocatalysis using the separable and recyclable carbon-fiber/semimetal Bi nanosheet arrays in the environment-related field.

8.
Nanoscale ; 12(19): 10809-10815, 2020 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-32392273

RESUMO

Glucose detection using surface-enhanced Raman scattering (SERS) spectroscopy has aroused considerable attention due to its potential in the prevention and diagnosis of diabetes as a result of its unique molecular fingerprinting capability, ultrahigh sensitivity and minimal interference from water. Despite numerous solutions to improve the sensitivity of glucose detection, the development of a new SERS-based strategy to detect glucose with high sensitivity and low-cost is still required. In this study, we propose a simple and sensitive SERS-based plasmonic metasurface sensing platform for a glucose sandwich assay using self-assembled p-mercapto-phenylboronic acid (PMBA) monolayers on a gold nanodisk (Au-ND) metasurface and synthesized silver nanoparticles (Ag NPs) modified with a mixture of p-aminothiophenol (PATP) and PMBA. The localized near-field of the proposed plasmonic metasurface is markedly enhanced due to the coupling between the Au-ND and Ag NPs, which greatly improves detection sensitivity. The experimental results show that SERS signals of the glucose assay are significantly enhanced by more than 8-fold, in comparison with the SERS substrate of smooth Au films and Ag NPs. Moreover, the plasmonic metasurface-based glucose sandwich assay exhibits high selectivity and sensitivity for glucose over fructose and galactose. The developed plasmonic metasurface sensing platform shows enormous potential for highly sensitive and selective SERS-based glucose detection and opens a new avenue for scalable and cost-effective biosensing applications in the future.

9.
J Clin Neurosci ; 2020 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-32376156

RESUMO

Previous work at our institution treating arteriovenous malformation (AVM) with radiosurgery (RS) demonstrated superior nidus visualization and geometric accuracy with use of 3-dimensional rotational angiography (3DRA) compared to biplanar digital subtraction angiography. We have since adopted a unique radiosurgical protocol that utilizes 3DRA in the planning of linear accelerator (LINAC)-based RS delivered in a frameless manner. This study seeks to compare clinical outcomes between patients treated by this novel approach and those treated by our historic frame-based protocol. Clinical data were queried for all patients treated for AVM by single-fraction RS from 2003 to 2017. RICs were identified and classified as radiologic, symptomatic, or permanent. Excellent outcome was defined as nidus obliteration without intracranial hemorrhage (ICH) or symptomatic RIC. Clinical predictors of study outcomes were identified through univariate and multivariate logistic regression using backwards elimination to optimize a predictive model. 131 AVMs in 124 patients were included with a median follow-up of 88 months. 59 AVMs received frame-based RS and 72 AVMs received frameless RS. Rate of obliteration was 64% for frame-based RS and 61% for frameless RS (p = 0.70). Radiologic, symptomatic, and permanent RICs rates were 68%, 17%, and 8%, respectively, for frame-based cases, versus 40% (p < 0.01), 8% (p = 0.13), and 3% (p = 0.15), respectively, for frameless cases. Excellent outcome was achieved in 49% of frame-based cases and 53% of frameless cases (p = 0.68). These results illustrate the safety and effectiveness of frameless LINAC-based AVM RS utilizing 3DRA.

10.
J Am Chem Soc ; 142(17): 7968-7975, 2020 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-32266814

RESUMO

Ion migration has been recognized as a critical step in determining the performance of numerous devices in chemistry, biology, and material science. However, direct visualization and quantitative investigation of solid-phase ion migration among anisotropic nanostructures have been a challenging task. Here, we report an in-situ ChemTEM method to quantitatively investigate the solid-phase ion migration process among coassembled nanowires (NWs). This complicated process was tracked within a NW and between NWs with an obvious nanogap, which was revealed by both phase field simulation and ab initio modeling theoretical evaluation. A migration "bridge" between neighboring NWs was observed. Furthermore, these new observations could be applied to migration of other metal ions on semiconductor NWs. These findings provide critical insights into the solid-phase ion migration kinetics occurring in nanoscale systems with generality and offer an efficient tool to explore other ion migration processes, which will facilitate fabrication of customized and new heteronanostructures in the future.

11.
Chem Commun (Camb) ; 56(34): 4640-4643, 2020 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-32270142

RESUMO

A ratiometric fluorescent probe (PNA) was developed to sense and image endogenous bacterial penicillin G acylase (PGA). Oleanolic acid was discovered as a potential natural inhibitor of PGA using high-throughput screening techniques based on PNA.

12.
Int J Mol Med ; 45(5): 1464-1476, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32323821

RESUMO

Knee osteoarthritis (KOA) is a major cause of leg disability in the elderly population. Recently, the expression levels of circulating microRNA (miRNA) let­7e have been reported to be significantly reduced in KOA. The aims of the present study were to assess the feasibility of let­7e as a serum marker for detecting KOA and to explore the underlying mechanisms of its involvement. Based on previous studies and bioinformatics analysis, let­7e may regulate apoptosis and autophagy of articular chondrocytes. A total of 10 patients with KOA and 10 patients with trauma without KOA were recruited to examine the levels of let­7e in peripheral blood. Subsequently, KOA rat models were established, and the levels of let­7e in the cartilage and serum were examined, the expression of apoptotic proteins and autophagy­related proteins in the cartilage were investigated, and apoptotic and autophagic activities of primary cultured chondrocytes were also detected. In patients with KOA, let­7e levels in the peripheral serum were significantly decreased compared with the control group, and this result was confirmed in the peripheral serum and cartilage of KOA rats. In addition, the expression levels of proteins involved in the apoptotic pathway were increased in the cartilage of KOA rats, and apoptotic activity was increased. The expression of autophagy­related proteins beclin 1 and microtubule associated protein 1 light chain 3 ß (LC3B) II/LC3BI in the articular cartilage of KOA rats was lower compared with the controls, and autophagy was decreased. Si­Miao­San (SMS) treatment restored the expression of let­7e and reversed the changes in apoptosis and autophagy. Therefore, the present study provided additional evidence that circulating let­7e may be a potential serum biomarker for the diagnosis and treatment of KOA. Elevated apoptosis levels and decreased autophagy levels of cartilage tissue are involved in KOA, and treatment with SMS may reverse these effects.

13.
J Colloid Interface Sci ; 573: 360-369, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32298929

RESUMO

A series of composites have been fabricated by introducing ionic liquid (IL) (ship) into chromium terephthalate MIL-101 (bottle) by ship-in-bottle method (IL@MIL-101s), the resulting IL@MIL-101s are endowed to high water retention, which is essential to proton conducting on multiple energy-involved applications at the low relative humidity (RH). The humidifying IL can lower water loss and increase water uptake, and thus improves water retention properties of the composites aided by the mesoporous MIL-101 at low RH. The hydropenic proton transfer pathways are modeled inside MOF and between IL-MOF, diminishing energy barrier routes for proton hopping, and thus a promotive proton transfer is rendered via Grotthuss mechanism. Specially, the IL@MIL-101 (SIB-3) unfolds a high proton conductivity (σ = 4.4 × 10-2 S cm-1) at RH as low as ~23%, five orders of magnitude increase than that of parent MIL-101 (1.1 × 10-7 S cm-1) at 323 K. Besides, IL@MIL-101s as fillers are incorporated into polymer blends to form hybrid membranes, appearing the relatively high proton conductivity (4.3 × 10-3 S cm-1) under ~23% RH at 323 K.

14.
ACS Appl Mater Interfaces ; 12(19): 22002-22011, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32329995

RESUMO

Owing to their unique superiorities in chemical and photoluminescence (PL) stability, low toxicity, biocompatibility, and easy functionalization, graphene quantum dots (GQDs) are widely used in cell imaging, probes, and sensors. However, further development and deeper research of GQDs are restricted by their imprecise and complex structure and accompanying controversial PL mechanism. In this work, two kinds of structure-defined water-soluble GQDs, with different oxidation degrees, are synthesized from molecules using bottom-up syntheses methods. After being studied by a series of characterizations, their optical properties, functional groups, molecular weight, and structural information were obtained. The optical properties of GQDs could be optimized by controlling their oxidation degree. The PL mechanism of GQDs was investigated by comparing their structure and properties. Furthermore, robust, stable, and precise temperature probes were designed using the GQDs, which exhibited an excellent wide response range, covering the whole physiology temperature range, from 0 to 60 °C in water. Moreover, the GQDs were successfully applied as temperature-responsive fluorescence probes in the HeLa cell line. These works laid a solid foundation for further applications of GQDs as biological thermoprobes and selectively temperature detectors in vitro cellular and in vivo.

15.
Sensors (Basel) ; 20(7)2020 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-32235400

RESUMO

Emergency communications need to meet the developing demand of equipment and the complex scenarios of network in public safety networks (PSNs). Heterogeneous Cloud Radio Access Network (H-CRAN), an important technology of the 5th generation wireless systems (5G), plays an important role in PSN. H-CRAN has the features of resource sharing and centralized allocation which can make up for resource shortage in emergency communications. Therefore, an emergency communications strategy based on Device-to-device (D2D) multicast is proposed to make PSN more flexible and rapid. Nearby users can communicate directly without a base station through D2D. This strategy may guarantee high speed data transmission and stable continuous real-time communications. It is divided into three steps. Firstly, according to the distance between users, the alternative cluster head is divided. Secondly, two kinds of cluster head user selection schemes are developed. One is based on terminal power and the other is based on the number of extended users. Last but not least, the Hungarian Algorithm based on throughput-aware is used to channel multiplexing. The numerical results show that the proposed scheme can effectively extend the coverage of PSN and optimize the utilization of resources.

16.
JAMA Netw Open ; 3(4): e201929, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32236532

RESUMO

Importance: Historical data suggest that there is an overall survival benefit associated with prophylactic cranial irradiation (PCI) in patients with small cell lung cancer (SCLC). However, as the fidelity of magnetic resonance imaging (MRI) of the brain continues to improve, this idea is now being questioned, with recent research showing no survival benefit associated with PCI in extensive-stage SCLC; however, the role for PCI is not clear in patients with limited-stage SCLC (LS-SCLC). Objective: To report the overall survival and rates of intracranial control for patients with LS-SCLC, all staged with MRI, who either did or did not undergo PCI. Design, Setting, and Participants: This cohort study included 297 patients with LS-SCLC at a large US academic cancer center. Patients were treated with thoracic radiation; 205 also underwent PCI and 92 did not. All patients underwent at least baseline MRI, with restaging brain MRI and/or computed tomography; they did not have disease progression after thoracic radiation treatment. A propensity score-matching analysis was undertaken in an attempt to adjust for potential bias. Of the 297 patients who met the inclusion criteria, the propensity score was calculated for 295 patients, using patient, tumor, and treatment characteristics. Data were analyzed in October 2019. Intervention: Prophylactic cranial irradiation in patients with LS-SCLC. Main Outcomes and Measures: The rate of overall survival and intracranial control. Results: Of the 297 patients, 162 (54.5%) were men. The median age was 62.2 years (range, 27.0-85.0 years) for patients who underwent PCI and 68.6 years (range, 40.0-86.0 years) for those who did not undergo PCI. The 3-year cumulative incidence rate of brain metastases was higher in the no-PCI group vs the PCI group, when counting death as a competing risk, but the difference was not statistically significant (20.40% [95% CI, 12.45%-29.67%] vs 11.20% [95% CI, 5.40%-19.20%]; P = .10). The use of PCI was not associated with a difference in overall survival between the patient groups (hazard ratio, 0.844; 95% CI, 0.604-1.180; P = .32). Conclusions and Relevance: These findings suggest that patients with LS-SCLC staged with MRI who undergo PCI after thoracic radiation treatment were not associated with a decreased risk of developing new brain metastases compared with patients who do not undergo PCI. The use of PCI was not associated with an overall survival benefit for such patients.

17.
J Comp Neurol ; 2020 Apr 04.
Artigo em Inglês | MEDLINE | ID: mdl-32246847

RESUMO

Depression is a mental illness which is harmful seriously to the society. This study investigated the effects of fluoxetine on the CNPase+ oligodendrocytes in hippocampus of the depressed rats to explore the new target structure of antidepressants. Male Sprague-Dawley rats were used to build chronic unpredictable stress (CUS) depressed model of rats. Then, the depressed rats were divided into the CUS standard group and the CUS + fluoxetine (CUS/FLX) group. The CUS/FLX group was treated with fluoxetine at dose of 5 mg/(kg·d) from the fifth week to seventh week. After 7 weeks CUS intervention, the sucrose preference of the CUS standard group was significantly lower than that of the control group and the CUS/FLX group. The stereological results showed that the total number of the CNPase+ cells in the CA1, CA3, and DG subfield of the hippocampus in the CUS standard group were significantly decreased, when compared with the CNPase+ cells in the control group. However, the total number of the CNPase+ cells in the CA1 and CA3 subfield of the hippocampus in the CUS standard group was significantly decreased when it compared with CNPase+ cells in the CUS/FLX group. Therefore, fluoxetine might prevent the loss of CNPase+ oligodendrocytes in CA1 and CA3 subfields of hippocampus of the depressed rats. The oligodendrocytes in hippocampus may play an important role in the pathogenesis of depression. The current result might provide structural basis for the future studies that search for new antidepressant strategies.

18.
J Affect Disord ; 270: 118-123, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32339101

RESUMO

BACKGROUND: It has been demonstrated that a reduction in the amount of high-frequency cardiopulmonary coupling (CPC) is indicative of unstable sleep in unmedicated patients with major depressive disorder (MDD). Considering the close relationship between sleep quality and memory consolidation, this study sought to investigate the potential of high-frequency CPC as a novel biomarker for objective evaluation of memory impairment in MDD. METHODS: A total of 64 depressed patients and 35 healthy controls were included in this cross-sectional study. High-frequency coupling (HFC) was assessed by electrocardiogram-based CPC analysis using a portable sleep-respiration monitor during sleep for one night. The next day, subjects completed the cognition assessment with the Assessment of Neuropsychological Status (RBANS). The 17-Item Hamilton Depression Rating Scale (HAMD17) and the Hamilton Rating Scales for Anxiety (HAMA) were used to evaluate the severity of depression and anxiety in each patient, respectively. RESULTS: There was no significant difference in the proportion of HFC between depressed patients and healthy controls. In patients with low HFC proportion (<35%), severe anxiety could significantly decrease HFC proportion. The HFC proportion positively correlated with immediate and delayed memory in depressed patients. Further analysis showed that patients with low HFC proportion may have worse delayed memory. LIMITATIONS: The lack of prior exposure to the monitoring equipment and procedure could have generated artefacts that would have disappeared after habituation. CONCLUSIONS: These results support a positive correlation between the HFC proportion and memory in depressed patients. Further research is required to explore the clinical implications of these findings.

19.
Sensors (Basel) ; 20(8)2020 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-32340199

RESUMO

Stress wave, accompanied by explosion shock wave overpressure measurement and dynamic pressure calibration on shock tube, could cause error signals in the piezoelectric pressure sensor (PPS) used for measuring and calibrating. We may call this error the stress wave effect (SWE). In this paper, the SWE and its isolation from PPS were studied by using a split Hopkinson pressure bar (SHPB). In the experimental study of SWE, when increasing the input stress, the corresponding output signal of the PPS was analyzed, and the existence of SWE was verified using the result of the spectrum analysis of the output signal. The stress wave isolation pedestal used in the stress wave isolation experiment was made of nylon and plexiglass polymer materials. The effects of the isolation pedestal's materials and length on the stress wave isolation were analyzed using the study results. Finally, an artificial neural network (ANN) was trained with the data of the SWE study and was further applied to compensate the SWE error of the PPS output signal. The compensating results were compared with the isolating results, and the advantages and disadvantages of the digital compensation and physical isolation methods were analyzed.

20.
J Colloid Interface Sci ; 574: 174-181, 2020 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-32311539

RESUMO

Potassium-ion batteries (KIBs) have becoming a prospective energy storage technique, due to the abundant potassium resources in the earth crust, approximate redox potential and similar electrochemical behavior of potassium and lithium. However, the insufficient capacity, poor stability and volume expansion of electrode materials during charge and discharge are main factors restricting the further development of KIBs. This work reports an amorphous carbon coated SnO2 nanohseets on hard carbon hollow spheres (AC/SnO2@HCHS) anode with enhanced potassium storage performance. The HCHS acts as a carrier for SnO2 nanosheets, providing high electrical conductivity and stable skeleton. The self-assembled SnO2 nanosheets with high surface area ensures sufficient contact with the electrolyte. Amorphous carbon wrapping can not only relieve SnO2 volume expansion but also provide surface-induced capacitive capacity. As a consequence, the AC/SnO2@HCHS anode presents excellent potassium-ion storage performance with high discharge capacity of 346 mAh g-1 at 0.1 A g-1 over 200 cycles, ultra-long cycling lifetime and outstanding rate capability (236 mAh g-1 at 1 A g-1 over 1000 cycles).

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