Publications by authors named "Bei Peng"

31 Publications

Pressure-Driven and Creep-Enabled Interface Evolution in Sodium Metal Batteries.

ACS Appl Mater Interfaces 2021 Jun 25;13(22):26533-26541. Epub 2021 May 25.

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

All-solid-state batteries (ASSBs) using an alkali metal anode and a solid-state electrolyte (SE) face several problems due to poor physical and electrical contact. Recent experiments have shown that applying a stack pressure can improve the interface contact and suppress void formation. The mechanical properties of Na metal are different from those of Li metal, leading to differences in the mechanisms of the pressure-dependent interface evolution. Herein, we report a three-dimensional time-dependent model for tracking the evolution of interfaces formed between Na metal and Na-β″-alumina SE. Our results show that Na metal contacts more conformally with the SE, providing a lower interfacial resistance, compared with Li metal, assuming equal resistance due to contamination. The differences due to contact elastoplasticity are larger than the differences in metal creep effects. In fact, we show that increased stack pressure can lead to lower creep because the contact is more conformal at high pressures. Our excellent agreement with recent experiments determines an effective hardness of Na in the Na-SE batteries to be 15 MPa. The results further reveal that the pressure dependence of void suppression is dominated by contact elastoplasticity.
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http://dx.doi.org/10.1021/acsami.0c22006DOI Listing
June 2021

Use of Rituximab After Orbital Decompression Surgery in Two Grave's Ophthalmopathy Patients Progressing to Optic Neuropathy.

Front Endocrinol (Lausanne) 2020 26;11:583565. Epub 2020 Oct 26.

Department of Endocrinology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.

Background: While orbital decompression can alleviate optic nerve compression and prevent further vision loss in dysthyroid optic neuropathy (DON), it cannot relieve inflammatory symptoms. Very high doses of intravenous glucocorticoids (GCs) are the first-line therapy for DON; however, the effective rate is only 40% and might be much lower in patients who fail high-dose GC pulse therapy and progressed to DON. The results of two case series studies indicated that rituximab treatment had a much better curative effect compared to very high doses of intravenous GCs, but some patients required urgent orbital decompression after rituximab injection because rituximab might lead to the release of cytokines, aggravated intraorbital edema, and further vision loss.

Methods: We retrospectively studied the therapeutic process of two Grave's ophthalmopathy (GO) patients complicated with DON who failed high-dose GC pulse therapy and underwent orbital decompression. Both patients received single-dose (500 mg) rituximab treatment.

Results: During more than 2 years of follow-up, rituximab treatment exhibited significant improvement in inflammatory symptoms, as manifested by a substantial decrease in Clinical Activity Score (CAS); meanwhile, the vision of both patients improved significantly and their diplopia was relieved.

Conclusions: The results of this study were consistent with those of two previous case series studies indicating the significant and lasting effect of rituximab treatment on DON, especially for patients with GC resistance or recurrence after GC therapy. Orbital decompression before rituximab treatment might reduce the incidence of rapid vision loss and urgent orbital decompression surgery caused by aggravated orbital edema after rituximab injection; however, the necessity for preventive decompression surgery requires further study.
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http://dx.doi.org/10.3389/fendo.2020.583565DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7649761PMC
June 2021

Origin of Magnetically Induced Optical Transmission of Magnetic Nanocomposite Films.

Polymers (Basel) 2020 Oct 29;12(11). Epub 2020 Oct 29.

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

Herein, we present an investigation on the origin of the magnetically induced optical transmission of composite films comprised of polydimethylsiloxane and magnetic nanofillers via experiment and simulation. Structured and unstructured films were used in the study, which were fabricated with and without magnetic fields, respectively. Altered optical transmittance was observed from both types of films when they were subjected to an external magnetic field. Numerical analyses were performed to investigate the effect of the particle movement under magnetic field and the film magnetostriction on the film optical transmittance. The simulation results show that the changed light transmission under magnetic field is mainly due to a variation in the film thickness resulting from the film magnetostriction. The ellipsometric analysis results confirm the altered film thickness in response to the external magnetic field, and the measurements of the film magnetostrictive stresses validate that there is magnetostriction in the magnetic composite films. Additionally, it is indicated that there might be some relationship between the magnetically induced optical transmission and the film magnetostrictive stress under certain conditions.
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http://dx.doi.org/10.3390/polym12112533DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7693415PMC
October 2020

Curcumin improves necrotising microscopic colitis and cell pyroptosis by activating SIRT1/NRF2 and inhibiting the TLR4 signalling pathway in newborn rats.

Innate Immun 2020 10 13;26(7):609-617. Epub 2020 Sep 13.

Department of Emergency Medicine, Xuzhou Children's Hospital, Xuzhou Medical University, PR China.

This study aimed to explore comprehensively the biological function of curcumin, and its underlying mechanism, in protecting from necrotising microscopic colitis in newborn rats. A total of 20 normal healthy rats were selected, and a necrotising enterocolitis (NEC) model was established. After hypoxia and hypothermia stimulation, these rats were treated with different doses of curcumin (control group, NEC model group, NEC+20 mg/kg curcumin and NEC+50 mg/kg curcumin). Inflammation was identified using hematoxylin and eosin staining, and inflammatory factors were detected via ELISA. The mRNA and protein levels of SIRT1, NRF2, TLR4, NLRP3 and caspase-1 were determined by quantitative RT-PCR and Western blotting, respectively. Curcumin improved the inflammatory condition of NEC and inhibited the expression of inflammatory factors in NEC newborn rat intestinal tissue. Furthermore, the SIRT1/NRF2 pathway was inhibited in the intestinal tissue of NEC newborn rats, whereas curcumin treatment induced the activation of the SIRT1/NRF2 pathway and inhibited TLR4 expression in these animals. In addition, curcumin could also inhibit the expression of inflammatory factors and alleviate the LPS/ATP-induced focal death pathway in intestinal epithelial cells through the SIRT1 pathway. Curcumin can improve necrotising microscopic colitis and cell pyroptosis by attenuating NEC-induced inhibition of SIRT1/NRF2 and inhibiting the TLR4 signalling pathway in newborn rats.
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http://dx.doi.org/10.1177/1753425920933656DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7556186PMC
October 2020

Impacts of Residual Stress on Micro Vibratory Platform Used for Inertial Sensor Calibration.

Sensors (Basel) 2020 Jul 16;20(14). Epub 2020 Jul 16.

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

A micro vibratory platform driven by converse piezoelectric effects is a promising in-situ recalibration platform to eliminate the influence of bias and scale factor drift caused by long-term storage of micro-electro-mechanical system (MEMS) inertial sensors. The calibration accuracy is critically determined by the stable and repeatable vibration of platform, and it is unavoidably impacted by the residual stress of micro structures and lead zirconate titanate (PZT) hysteresis. The abnormal phenomenon of the observed displacement response in experiments was investigated analytically using the stiffness model of beams and hysteresis model of piezoelectric material. Rather than the hysteresis, the initial deflection formed by the residual stress of the beam was identified as the main cause of the response error around the zero position. This conclusion provides guidelines to improve the performance and control of micro vibratory platforms.
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http://dx.doi.org/10.3390/s20143959DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7411899PMC
July 2020

Design of a Silicon Photocatalyst for High-Efficiency Photocatalytic Water Splitting.

ACS Omega 2020 Mar 20;5(12):6358-6365. Epub 2020 Mar 20.

CAS Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China.

Metallurgical silicon was studied for photocatalytic H evolution activity. It has been found that metallurgical silicon with large particle size (above 800 nm) possesses poor photocatalytic activity because of the deteriorating photoelectric performance of the low-purity silicon. After size reduction (around 400 nm) and metal nanoparticle decoration, the photocatalytic performance was significantly enhanced to 1003.3 μmol·g·h. However, the photocatalytic performance of the Cu-, Ag-, and Pt-decorated silicon is degraded with the increase of time. Moreover, the degradation is independent of the metal. Electrochemical test and X-ray photoelectron spectroscopy suggested that the Mott-Schottky effect in the metal-silicon contact should be responsible for the degradation. After forming a heterojunction by vulcanizing the Ag-decorated silicon, the degradation was suppressed. Upgradation of the metal-silicon contact to form a heterojunction was a promising way to suppress the degradation and retain the high photocatalytic performance.
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http://dx.doi.org/10.1021/acsomega.9b03755DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7114140PMC
March 2020

An Overview of Molecular Mechanism, Clinicopathological Factors, and Treatment in NUT Carcinoma.

Biomed Res Int 2019 11;2019:1018439. Epub 2019 Nov 11.

Dalian Medical University, Dalian 116000, China.

NUT carcinoma (NC) is a rare and poorly differentiated tumor, with highly aggressive and fatal neoplasm. NC is characterized by chromosomal rearrangement involving NUTM1 gene, but lack of specific clinical and histomorphological features. It is more common in midline anatomic sites, such as head and neck, mediastinum, and other midline organs. NC may occur at any age, but mainly in children and young adults. In addition, male and female are equally affected. Most clinicians lack a clear understanding of the disease, and NC diagnostic reagents are still not widely used; therefore, misdiagnosis often occurs in clinic. Due to the highly aggressive nature of the disease and the insensitivity to nonspecific chemotherapy or radiotherapy, many patients have died before the confirmation of NC. In fact, the true incidence of NC is much higher than the current statistics. In recent years, targeted therapy for NC has also made some progress. This article aims to summarize the molecular mechanisms, clinicopathological characteristics, and treatment of NC.
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http://dx.doi.org/10.1155/2019/1018439DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6877965PMC
April 2020

Improvement on Selective Laser Sintering and Post-Processing of Polystyrene.

Polymers (Basel) 2019 Jun 1;11(6). Epub 2019 Jun 1.

School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

Amorphous polymers are heavily utilized materials in selective laser sintering (SLS) due to their good dimensional accuracy. However, sintered parts of amorphous polymers cannot be used as functional parts owing to their poor forming performance, including their low relative densities and tensile strength. Therefore, post-processing methods are employed to enhance the mechanical properties of amorphous polymers SLS parts without damaging their relatively high dimensional accuracy. In this study, the forming process of selective laser sintering (SLS) and post-processing on polystyrene (PS) was investigated. The orthogonal experiment was designed to obtain the optimal combination of process parameters. The effect of a single process parameter and the laser volumetric energy density (LVED) on dimension accuracy and warpage of the sintered parts were also discussed. In addition, a three-dimensional (3D) thermal model was developed to analyze the temperature fields of single-layer SLS parts and PS powder sintering mechanism. Then, infiltrating with epoxy resin was employed to enhance the mechanical properties of the PS parts. Good resin-infiltrated formulation was obtained based on the mechanical property tests and fractured surface analysis. This research provides guidance for SLS process and post-processing technology in polymers.
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http://dx.doi.org/10.3390/polym11060956DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6631003PMC
June 2019

Comparison of desflurane and sevoflurane on postoperative recovery quality after tonsillectomy and adenoidectomy in children.

Exp Ther Med 2019 Jun 4;17(6):4561-4567. Epub 2019 Apr 4.

Department of Anesthesiology, Xuzhou Children's Hospital, Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China.

Comparison of desflurane and sevoflurane on the postoperative recovery quality after tonsillectomy and adenoidectomy in children was carried out. A retrospective analysis was performed on the medical records of 165 children who underwent tonsil and adenoid radiofrequency ablation under low-temperature plasma and were admitted to the Xuzhou Children's Hospital, Xuzhou Medical University from February 2014 to May 2017. In total, 79 children with sevoflurane anesthesia were in the sevoflurane group, and 86 children with desflurane anesthesia in the desflurane group. The non-invasive blood pressure (NIBP), heart rate (HR) and oxygen saturation (SpO) level, the postoperative sedation (Ramsay) scores, the modified objective pain score (MOPS) of children were recorded. The pediatric anesthesia emergence delirium (PAED) scores of children were recorded. Children in the sevoflurane group had longer operation time, anesthesia time, extubation time and coincidence time than those in the desflurane group (P<0.05). At the beginning of operation (t1), 10 min after operation (t2), at the time of entering anesthesia recovery room (t3), at the time of tracheal catheter extubated (t4), 10 min after extubation (t5), and at the time of leaving the anesthesia recovery room (t6), children in the sevoflurane had higher NISBP and NIDBP, lower HR than those in the desflurane group (P<0.05). At the time of the tracheal catheter extubation (c2), 10 min after extubation (c3), 30 min after extubation (c4), children in the sevoflurane group had lower Ramsay scores and higher PAED scores than those in the desflurane group (P<0.05). More suitable as an anesthetic maintenance drug for tonsillectomy and adenoidectomy in children, desflurane has a better anesthetic effect and is safer. In addition, children with desflurane anesthesia have high postoperative recovery quality and quick recovery in the short term, with better sedative and analgesic effects. Therefore, it is worthy of promotion in clinic practice.
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http://dx.doi.org/10.3892/etm.2019.7467DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6488999PMC
June 2019

Efficacy and safety of propofol in preventing emergence agitation after sevoflurane anesthesia for children.

Exp Ther Med 2019 Apr 20;17(4):3136-3140. Epub 2019 Feb 20.

Children's Hospital of Xuzhou Medical University, Xuzhou, Jiangsu 221006, P.R. China.

Application of propofol in preventing emergence agitation after sevoflurane anesthesia in children was evaluated. Clinical data of 200 children who received sevoflurane anesthesia in Children's Hospital of Xuzhou Medical University were retrospectively analyzed. Among them, 120 patients who received inhaled sevoflurane for pediatric anesthesia and intravenous infusion of propofol (2 mg/kg) were included in observation group. The remaining 80 cases who were directly anesthetized by sevoflurane alone were the control group. T PAED scores, modified Aldrete scores, extubation time, PACU time and adverse reactions (gastrointestinal tract and respiratory response) were analyzed and compared between the control and observation group. PAED scores, extubation time, PACU time and incidence of adverse reactions were significantly lower in observation than in control group, and the modified Aldrete scores were higher in observation than in control group (P<0.05). Spearman's correlation analysis showed that the PAED scores were negatively correlated with modified Aldrete scores and positively correlated with extubation time. There was positive correlation between the PACU time and incidence of adverse reactions and between the PAED scores and extubation time. There was negative correlation between PACU time and incidence of adverse reactions and between Aldrete scores and extubation time (P<0.05). Therefore, we conclude that propofol can be used to prevent agitation after sevoflurane anesthesia in children.
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http://dx.doi.org/10.3892/etm.2019.7289DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6425276PMC
April 2019

Recent advances in thread-based microfluidics for diagnostic applications.

Biosens Bioelectron 2019 May 8;132:171-185. Epub 2019 Mar 8.

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, China. Electronic address:

Over the past decades, researchers have been seeking attractive substrate materials to keep microfluidics improving to outbalance the drawbacks and issues. Cellulose substrates, including thread, paper and hydrogels are alternatives due to their distinct structural and mechanical properties for a number of applications. Thread have gained considerable attention and become promising powerful tool due to its advantages over paper-based systems thus finds numerous applications in the development of diagnostic systems, smart bandages and tissue engineering. To the best of our knowledge, no comprehensive review articles on the topic of thread-based microfluidics have been published and it is of significance for many scientific communities working on Microfluidics, Biosensors and Lab-on-Chip. This review gives an overview of the advances of thread-based microfluidic diagnostic devices in a variety of applications. It begins with an overall introduction of the fabrication followed by an in-depth review on the detection techniques in such devices and various applications with respect to effort and performance to date. A few perspective directions of thread-based microfluidics in its development are also discussed. Thread-based microfluidics are still at an early development stage and further improvements in terms of fabrication, analytical strategies, and function to become low-cost, low-volume and easy-to-use point-of-care (POC) diagnostic devices that can be adapted or commercialized for real world applications.
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http://dx.doi.org/10.1016/j.bios.2019.03.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7127036PMC
May 2019

New advances in microfluidic flow cytometry.

Electrophoresis 2018 Sep 22. Epub 2018 Sep 22.

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, P. R. China.

In recent years, researchers are paying the increasing attention to the development of portable microfluidic diagnostic devices including microfluidic flow cytometry for the point-of-care testing. Microfluidic flow cytometry, where microfluidics and flow cytometry work together to realize novel functionalities on the microchip, provides a powerful tool for measuring the multiple characteristics of biological samples. The development of a portable, low-cost, and compact flow cytometer can benefit the health care in underserved areas such as Africa or Asia. In this article, we review recent advancements of microfluidics including sample pumping, focusing and sorting, novel detection approaches, and data analysis in the field of flow cytometry. The challenge of microfluidic flow cytometry is also examined briefly.
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http://dx.doi.org/10.1002/elps.201800298DOI Listing
September 2018

Numerical and experimental investigation of 'water fan' effect due to electrohydrodynamic force in a microchamber.

Electrophoresis 2018 Sep 5. Epub 2018 Sep 5.

School of Engineering, University of Guelph, Guelph, Canada.

Electrohydrodynamics is commonly used in microfluidics to control and manipulate the fluid. Though there are studies on the rotation flow in suspended films, the thin film liquid is easily broken and cannot last long hence not applicable in specific applications. Here, we established a three-dimensional microchamber embedded with two pairs of microelectrodes to investigate the rotational phenomenon of bulk of liquid which we called 'water fan' effect based on the electrohydrodynamics force. When proper voltages were applied on these microelectrodes, the tornado-like rotation would be generated. Both the numerical and experimental results showed that the controllable and continuous rotation could be achieved in the microchamber. In addition, the concentration effect resulting from the rotation flow was also observed. The proposed method offers great promises in providing theoretical and practical guideline in microfluidic devices for mixing, separating, and cooling applications.
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http://dx.doi.org/10.1002/elps.201800269DOI Listing
September 2018

The Insertion Mechanism of a Living Cell Determined by the Stress Segmentation Effect of the Cell Membrane during the Tip-Cell Interaction.

Small 2018 05 2;14(22):e1703868. Epub 2018 May 2.

School of Mechanical and Electrical Engineering, University of Electronic Science and Technology of China, Chengdu, Sichuan, 611731, P. R. China.

Atomic force microscopy probes are proved to be powerful tools to measure and manipulate the individual cell, providing potential applications for the controlled drug/protein delivery. However, the measured insertion efficiency varies dramatically from 20 to 80%, in some cases, the nanotip can never penetrate the cell membrane no matter how much force is applied to it. Thus, the insertion mechanism of a living cell during the tip-cell interaction must be thoroughly investigated before this technology comes into practical applications. In this work, a multistructural cell model is established to study the tip-membrane interaction. The simulation results show that the stress of the cell membrane can be divided into two stages by the stress segmentation point S. After point S, the stress of the cell membrane increases slightly and most of the indentation force is allocated to the cytoskeleton. This phenomenon is called "stress segmentation effect of the cell membrane," which confirms the hypothesis based on the experimental studies. Moreover, according to the experimental and numerical studies, the hypothesis of the stress segmentation effect also explains the reason that modifying the cell membrane or using the manmade sharpened nanotip can increase the insertion efficiency.
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http://dx.doi.org/10.1002/smll.201703868DOI Listing
May 2018

Mechanical Properties Optimization of Poly-Ether-Ether-Ketone via Fused Deposition Modeling.

Materials (Basel) 2018 Jan 30;11(2). Epub 2018 Jan 30.

School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

Compared to the common selective laser sintering (SLS) manufacturing method, fused deposition modeling (FDM) seems to be an economical and efficient three-dimensional (3D) printing method for high temperature polymer materials in medical applications. In this work, a customized FDM system was developed for polyether-ether-ketone (PEEK) materials printing. The effects of printing speed, layer thickness, printing temperature and filling ratio on tensile properties were analyzed by the orthogonal test of four factors and three levels. Optimal tensile properties of the PEEK specimens were observed at a printing speed of 60 mm/s, layer thickness of 0.2 mm, temperature of 370 °C and filling ratio of 40%. Furthermore, the impact and bending tests were conducted under optimized conditions and the results demonstrated that the printed PEEK specimens have appropriate mechanical properties.
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http://dx.doi.org/10.3390/ma11020216DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5848913PMC
January 2018

Glass Polarization Induced Drift of a Closed-Loop Micro-Accelerometer.

Materials (Basel) 2018 Jan 20;11(1). Epub 2018 Jan 20.

Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China.

The glass polarization effects were introduced in this paper to study the main cause of turn-on drift phenomenon of closed-loop micro-accelerometers. The glass substrate underneath the sensitive silicon structure underwent a polarizing process when the DC bias voltage was applied. The slow polarizing process induced an additional electrostatic field to continually drag the movable mass block from one position to another so that the sensing capacitance was changed, which led to an output drift of micro-accelerometers. This drift was indirectly tested by experiments and could be sharply reduced by a shielding layer deposited on the glass substrate because the extra electrical filed was prohibited from generating extra electrostatic forces on the movable fingers of the mass block. The experimental results indicate the average magnitude of drift decreased about 73%, from 3.69 to 0.99 mV. The conclusions proposed in this paper showed a meaningful guideline to improve the stability of micro-devices based on silicon-on-glass structures.
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http://dx.doi.org/10.3390/ma11010163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5793661PMC
January 2018

The influence of dexmedetomidine on the emergence agitation of pediatric patients after the operations of sense organs under general anesthesia using sevoflurane.

Minerva Pediatr 2017 Dec 21. Epub 2017 Dec 21.

Department of Anesthesiology, Xuzhou Children's Hospital, Jiangsu, P.R. China -

Background: We investigated the influence of dexmedetomidine on the emergence agitation of pediatric patients after ophthalmologic operation under general anesthesia using sevoflurane.

Methods: We selected 90 patients that were administered pediatric ophthalmologic operation for the study. The patients were randomly divided into 3 groups according to the administration way of drugs, i.e. the normal saline group (Group S, n = 30), the midazolam group (Group M, n = 30) and the dexmedetomidine group (Group D, n = 30). For all patients, anesthesia induction was performed using sevoflurane before anesthesia, and the anesthesia was maintained in the operation with a combination of sevoflurane and remifentanil; laryngeal mask airway (LMA) was used for assisted ventilation. 10 minutes before the end of operation, 15mL of 0.9% normal saline, 0.05mg/kg of midazolam and 0.5μg/kg of dexmedetomidine were administered to Group S, Group M and Group D, respectively. After the operation, we observed the awakening time, time of the LMA removal as well as the recovery time in the post anesthesia care unit (PACU) of patients in all three groups. We evaluated the postoperative condition of sedation and agitation of the patients using Ramsay sedation scale, 5-point scale and pediatric anesthesia emergence deliriums scale (PAED) and performed statistical analysis.

Results: In the comparisons of awakening time, time of the LMA removal as well as the recovery time, we found that Group M was the longest sequentially followed by Group D and Group S with statistically significant differences (P < 0.05). While the comparison of the scores of Ramsay sedation scale revealed that Group D scored highest followed by Group M and Group S with statistically significant differences (P < 0.05), both of the comparisons of the scores of 5-point scale and PAED scale showed that Group D scored the lowest, followed by Group M and Group S in sequence with statistically significant differences (P < 0.05).

Conclusions: Dexmedetomidine can significantly lower the incidence of emergence agitation of pediatric patients after the ophthalmologic operation under sevoflurane anesthesia.
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http://dx.doi.org/10.23736/S0026-4946.17.04854-XDOI Listing
December 2017

Material Viscoelasticity-Induced Drift of Micro-Accelerometers.

Materials (Basel) 2017 Sep 14;10(9). Epub 2017 Sep 14.

Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China.

Polymer-based materials are commonly used as an adhesion layer for bonding die chip and substrate in micro-system packaging. Their properties exhibit significant impact on the stability and reliability of micro-devices. The viscoelasticity, one of most important attributes of adhesive materials, is investigated for the first time in this paper to evaluate the long-term drift of micro-accelerometers. The accelerometer was modeled by a finite element (FE) method to emulate the structure deformation and stress development induced by change of adhesive property. Furthermore, the viscoelastic property of the adhesive was obtained by a series of stress-relaxation experiments using dynamic mechanical analysis (DMA). The DMA curve was imported into the FE model to predict the drift of micro-accelerometers over time and temperature. The prediction results verified by experiments showed that the accelerometer experienced output drift due to the development of packaging stress induced by both the thermal mismatch and viscoelastic behaviors of the adhesive. The accelerometers stored at room temperature displayed a continuous drift of zero offset and sensitivity because of the material viscoelasticity. Moreover, the drift level of accelerometers experiencing high temperature load was relatively higher than those of lower temperature in the same period.
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http://dx.doi.org/10.3390/ma10091077DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5615731PMC
September 2017

Numerical Investigation of the Fracture Mechanism of Defective Graphene Sheets.

Materials (Basel) 2017 Feb 11;10(2). Epub 2017 Feb 11.

School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.

Despite the unique occurrences of structural defects in graphene synthesis, the fracture mechanism of a defective graphene sheet has not been fully understood due to the complexities of the defects. In this study, the fracture mechanism of the monolayer graphene with four common types of defects (single vacancy defect, divacancy defect, Stone-Wales defect and line vacancy defect) were investigated systematically for mechanical loading along armchair and zigzag directions, by using the finite element method. The results demonstrated that all four types of defects could cause significant fracture strength loss in graphene sheet compared with the pristine one. In addition, the results revealed that the stress concentration occurred at the carbon-carbon bonds along the same direction as the displacement loading due to the deficiency or twist of carbon-carbon bonds, resulting in the breaking of the initial crack point in the graphene sheet. The fracture of the graphene sheet was developed following the direction of the breaking of carbon-carbon bonds, which was opposite to that of the displacement loading.
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http://dx.doi.org/10.3390/ma10020164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5459152PMC
February 2017

The effect of preoperative anxiety on the pain and opioid consumption of children after tonsillectomy and adenoidectomy.

Minerva Pediatr 2018 10 27;70(5):498-500. Epub 2017 Mar 27.

Department of Anesthesiology, Xuzhou Children's Hospital, Xuzhou, China -

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http://dx.doi.org/10.23736/S0026-4946.17.04904-0DOI Listing
October 2018

The Configuration of Copolymer Ligands on Nanoparticles Affects Adhesion and Uptake.

Langmuir 2016 10 21;32(39):10136-10143. Epub 2016 Sep 21.

Department of Mechanical Engineering and Mechanics, Lehigh University , Bethlehem, Pennsylvania 18015, United States.

Nanoparticles (NPs) are promising carriers for targeted drug delivery, photodynamic therapy, and imaging probes. A fundamental understanding of the dynamics of polymeric NP targeting to bilayer membranes is important to enhance the design of NPs for higher adhesion, binding percentage, and efficiency. In this study, dissipative particle dynamics simulations are applied to investigate the adhesion and uptake processes of the rod, spherical, and striped NPs to cell membranes. It is observed that the striped ligands can prevent NPs from rotating even in active rotation. We further optimize striped NP to a more stabilized structure. Uptake processes of NPs with different configurations are thoroughly investigated in our simulations and among which Janus NP are indicated to improve the penetration rate to 100%. These findings provide better insight into patterned NP design and may help fabricate new NPs for biomedical applications.
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http://dx.doi.org/10.1021/acs.langmuir.6b02371DOI Listing
October 2016

Modeling Nanoparticle Targeting to a Vascular Surface in Shear Flow Through Diffusive Particle Dynamics.

Nanoscale Res Lett 2015 Dec 27;10(1):942. Epub 2015 May 27.

School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China,

Nanoparticles are regarded as promising carriers for targeted drug delivery and imaging probes. A fundamental understanding of the dynamics of polymeric nanoparticle targeting to receptor-coated vascular surfaces is therefore of great importance to enhance the design of nanoparticles toward improving binding ability. Although the effects of particle size and shear flow on the binding of nanoparticles to a vessel wall have been studied at the particulate level, a computational model to investigate the details of the binding process at the molecular level has not been developed. In this research, dissipative particle dynamics simulations are used to study nanoparticles with diameters of several nanometers binding to receptors on vascular surfaces under shear flow. Interestingly, shear flow velocities ranging from 0 to 2000 s(-1) had no effect on the attachment process of nanoparticles very close to the capillary wall. Increased binding energy between the ligands and wall caused a corresponding linear increase in bonding ability. Our simulations also indicated that larger nanoparticles and those of rod shape with a higher aspect ratio have better binding ability than those of smaller size or rounder shape.
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http://dx.doi.org/10.1186/s11671-015-0942-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4452588PMC
December 2015

Determination of optimal parameters for dual-layer cathode of polymer electrolyte fuel cell using computational intelligence-aided design.

PLoS One 2014 9;9(12):e114223. Epub 2014 Dec 9.

School of Mechatronics Engineering, University of Electronic Science and Technology of China, Chengdu, 611731, China; Robotic Research Center, University of Electronic Science and Technology of China, Chengdu, 611731, China.

Because of the demands for sustainable and renewable energy, fuel cells have become increasingly popular, particularly the polymer electrolyte fuel cell (PEFC). Among the various components, the cathode plays a key role in the operation of a PEFC. In this study, a quantitative dual-layer cathode model was proposed for determining the optimal parameters that minimize the over-potential difference η and improve the efficiency using a newly developed bat swarm algorithm with a variable population embedded in the computational intelligence-aided design. The simulation results were in agreement with previously reported results, suggesting that the proposed technique has potential applications for automating and optimizing the design of PEFCs.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0114223PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4260849PMC
September 2015

Modeling the Microstructure Curvature of Boron-Doped Silicon in Bulk Micromachined Accelerometer.

Materials (Basel) 2013 Jan 15;6(1):244-254. Epub 2013 Jan 15.

Institute of Electronic Engineering, China Academy of Engineering Physics, Mianyang 621900, China.

Microstructure curvature, or buckling, is observed in the micromachining of silicon sensors because of the doping of impurities for realizing certain electrical and mechanical processes. This behavior can be a key source of error in inertial sensors. Therefore, identifying the factors that influence the buckling value is important in designing MEMS devices. In this study, the curvature in the proof mass of an accelerometer is modeled as a multilayered solid model. Modeling is performed according to the characteristics of the solid diffusion mechanism in the bulk-dissolved wafer process (BDWP) based on the self-stopped etch technique. Moreover, the proposed multilayered solid model is established as an equivalent composite structure formed by a group of thin layers that are glued together. Each layer has a different Young's modulus value and each undergoes different volume shrinkage strain owing to boron doping in silicon. Observations of five groups of proof mass blocks of accelerometers suggest that the theoretical model is effective in determining the buckling value of a fabricated structure.
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http://dx.doi.org/10.3390/ma6010244DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5452111PMC
January 2013

Prediction of gap asymmetry in differential micro accelerometers.

Sensors (Basel) 2012 25;12(6):6857-68. Epub 2012 May 25.

School of Mechatronics Engineering, University of Electronic Technology and Science of China, Chengdu 611731, China.

Gap asymmetry in differential capacitors is the primary source of the zero bias output of force-balanced micro accelerometers. It is also used to evaluate the applicability of differential structures in MEMS manufacturing. Therefore, determining the asymmetry level has considerable significance for the design of MEMS devices. This paper proposes an experimental-theoretical method for predicting gap asymmetry in differential sensing capacitors of micro accelerometers. The method involves three processes: first, bi-directional measurement, which can sharply reduce the influence of the feedback circuit on bias output, is proposed. Experiments are then carried out on a centrifuge to obtain the input and output data of an accelerometer. Second, the analytical input-output relationship of the accelerometer with gap asymmetry and circuit error is theoretically derived. Finally, the prediction methodology combines the measurement results and analytical derivation to identify the asymmetric error of 30 accelerometers fabricated by DRIE. Results indicate that the level of asymmetry induced by fabrication uncertainty is about ±5 × 10(-2), and that the absolute error is about ±0.2 μm under a 4 μm gap.
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http://dx.doi.org/10.3390/s120606857DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3435955PMC
January 2013

Remote ischemic postconditioning protects the brain from global cerebral ischemia/reperfusion injury by up-regulating endothelial nitric oxide synthase through the PI3K/Akt pathway.

Brain Res 2012 Mar 26;1445:92-102. Epub 2012 Jan 26.

Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008, Hunan Province, PR China.

Remote ischemic postconditioning (RIPoC) attenuates ischemia/reperfusion (I/R) injury in the heart, lung and hind limb. RIPoC performed in the hind limb reduces brain injury following focal cerebral ischemia in rats. Whether RIPoC has a neuroprotective effect with respect to global cerebral I/R injury is, however, unknown, and the mechanism of neuroprotection needs further elucidation. Here we investigated whether RIPoC could reduce global cerebral I/R injury in rats and whether this neuroprotective effect was induced by up-regulating endothelial nitric oxide synthase (eNOS) through the phosphatidylinositol-3 kinase/Akt (PI3K/Akt) pathway. Global cerebral ischemia was performed via 8min of four-vessel occlusion. Neuronal density, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL)-positive cells and expression of Bcl-2 and Bax in the hippocampal CA1 region were assessed after reperfusion. Morris water maze task was used to quantify spatial learning and memory deficits after reperfusion. The expression of eNOS, phosphorylated eNOS (Ser1177), Akt and phosphorylated Akt (Ser473) in the CA1 region was measured after reperfusion. RIPoC significantly attenuated delayed neuronal death and reduced the spatial learning and memory deficits associated with global cerebral ischemia. Pre-administration of N(ω)-nitro-l-arginine methyl ester (a nonselective NOS inhibitor) significantly abolished the neuroprotective effect of RIPoC. Moreover, pre-administration of LY294002 (a highly selective inhibitor of PI3K) not only significantly reversed the neuroprotective effect of RIPoC, but also obviously inhibited the up-regulation of eNOS induced by RIPoC. Our findings suggest that RIPoC protects the brain against global cerebral I/R injury and that this neuroprotection is mediated by up-regulating eNOS through the PI3K/Akt pathway.
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http://dx.doi.org/10.1016/j.brainres.2012.01.033DOI Listing
March 2012

Effect of growth orientation and diameter on the elasticity of GaN nanowires. A combined in situ TEM and atomistic modeling investigation.

Nano Lett 2011 Feb 20;11(2):548-55. Epub 2010 Dec 20.

Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208-3111, USA.

We characterized the elastic properties of GaN nanowires grown along different crystallographic orientations. In situ transmission electron microscopy tensile tests were conducted using a MEMS-based nanoscale testing system. Complementary atomistic simulations were performed using density functional theory and molecular dynamics. Our work establishes that elasticity size dependence is limited to nanowires with diameters smaller than 20 nm. For larger diameters, the elastic modulus converges to the bulk values of 300 GPa for c-axis and 267 GPa for a- and m-axis.
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http://dx.doi.org/10.1021/nl103450eDOI Listing
February 2011

[Regulation of inflammatory pain by NF-κB and CX3CR1 at the spinal cord of rats].

Zhong Nan Da Xue Xue Bao Yi Xue Ban 2010 Nov;35(11):1167-73

Department of Anesthesiology, Xiangya Hospital, Central South University, Changsha 410008, China.

Objective: To observe the effect of intrathecal injection of nuclear factor-κB (NF-κB) inhibitor of pyrrolidine dithiocarbamate (PDTC) on pain sensitivity thresholds and the expression of spinal cord CX3C chemokine receptor 1 (CX3CR1) in monoarthritis (MA) model in rats.

Methods: Forty-eight Sprague-Dawley rats were randomly divided into 4 groups (12 each) after successful intrathecal catheterization: (1) sham operation with physiological saline group (the sham group); (2) MA with normal saline group (the MA group); (3) 10 μL 100 μmol/L PDTC before MA (the PDTC pre-treatment group); (4)MA before 10 μL 100 μmol/L PDTC (the PDTC post-treatment group). Normal saline or PDTC was injected 5 d after the intrathecal catheterization. Pain sensitivity thresholds were measured in the 4 groups before and after the intrathecal injection at different time points. Rat monoarthritis model was subsequently built by injecting complete Freund's adjuvant (CFA) into the left ankle joint of the rats. On day 3 after the intrathecal injection, expression of microglia in the L₅ spinal cord segment was observed by immunohistochemical method, and the lumbar segments L₄-L₅ of spinal cord were taken to perform RT-PCR to examine the expression of NF-κB mRNA and CX3CR1 mRNA.

Results: Compared with the MA group, the pain sensitivity thresholds in the sham group, the PDTC pre-treatment group and the PDTC post-treatment group at each time point after the intrathecal injection increased significantly (P<0.05), while microglia in the L₅ spinal cord segment decreased significantly (P<0.05) and expression of CX3CR1 mRNA and NF-κB mRNA in the lumbar segments L₄-L₅ of spinal cord decreased significantly (P<0.05).

Conclusion: The hyperalgesic effect of the CFA-induced model of monoarthritis can be relieved by intrathecal injection of NF-κB inhibitor PDTC. Its mechanism is possibly related to NF-κB signal pathway which is involved in the formation of inflammatory pain through regulating CX3CR1 expression.
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http://dx.doi.org/10.3969/j.issn.1672-7347.2010.11.009DOI Listing
November 2010

Experimental-computational investigation of ZnO nanowires strength and fracture.

Nano Lett 2009 Dec;9(12):4177-83

Department of Mechanical Engineering, Northwestern University, Evanston, Illinois 60208-3111, USA.

An experimental and computational approach is pursued to investigate the fracture mechanism of [0001] oriented zinc oxide nanowires under uniaxial tensile loading. A MEMS-based nanoscale material testing stage is used in situ a transmission electron microscope to perform tensile tests. Experiments revealed brittle fracture along (0001) cleavage plane at strains as high as 5%. The measured fracture strengths ranged from 3.33 to 9.53 GPa for 25 different nanowires with diameters varying from 20 to 512 nm. Molecular dynamic simulations, using the Buckingham potential, were used to examine failure mechanisms in nanowires with diameters up to 20 nm. Simulations revealed a stress-induced phase transformation from wurtzite phase to a body-centered tetragonal phase at approximately 6% strain, also reported earlier by Wang et al. (1) The transformation is partial in larger nanowires and the transformed nanowires fail in a brittle manner at strains as high as 17.5%. The differences between experiments and computations are discussed in the context of (i) surface defects observed in the ZnO nanowires, and (ii) instability in the loading mechanism at the initiation of transformation.
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http://dx.doi.org/10.1021/nl9023885DOI Listing
December 2009

Elasticity size effects in ZnO nanowires--a combined experimental-computational approach.

Nano Lett 2008 Nov 8;8(11):3668-74. Epub 2008 Oct 8.

Department of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, Illinois 60208-3111, USA.

Understanding the mechanical properties of nanowires made of semiconducting materials is central to their application in nano devices. This work presents an experimental and computational approach to unambiguously quantify size effects on the Young's modulus, E, of ZnO nanowires and interpret the origin of the scaling. A micromechanical system (MEMS) based nanoscale material testing system is used in situ a transmission electron microscope to measure the Young's modulus of [0001] oriented ZnO nanowires as a function of wire diameter. It is found that E increases from approximately 140 to 160 GPa as the nanowire diameter decreases from 80 to 20 nm. For larger wires, a Young's modulus of approximately 140 GPa, consistent with the modulus of bulk ZnO, is observed. Molecular dynamics simulations are carried out to model ZnO nanowires of diameters up to 20 nm. The computational results demonstrate similar size dependence, complementing the experimental findings, and reveal that the observed size effect is an outcome of surface reconstruction together with long-range ionic interactions.
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http://dx.doi.org/10.1021/nl801724bDOI Listing
November 2008
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