Showing papers by "Jian Chen published in 2017"

Temperature Effect on Performance of Triboelectric Nanogenerator

Abstract: The triboelectric nanogenerator (TENG) is a promising energy harvesting technology that can convert mechanical energy into electricity and can be used as self-powered active sensors. However, previous studies are mostly carried out at room temperature without considering the temperature effect on the electrical performance of TENGs, which is critical for the application of electronics powered by TENGs in different regions in the world. In the present work, a TENG that worked in the single-electrode and contact-separation mode is utilized to reveal the influence of environment temperature on the electrical performance of TENG. The electrical performance of the TENG shows a decreasing tendency, as the temperature rises from −20 to 150 °C, which is controlled by the temperature-induced changes in the ability of storing and gaining electrons for polytetrafluoroethylene (PTFE). The storing electron ability change of PTFE is attributed to two aspects: one is the reduction of relative permittivity of PTFE sheet as the temperature increases, and the other is the variations of effective defects such as the escape of trapped charges in shallow traps and surface oxidation under the effect of temperature perturbation. This work can provide useful information for the application of TENG in both electric power generation and self-powered sensors in the harsh environment.

Broadband and high modulation-depth THz modulator using low bias controlled VO 2 -integrated metasurface

Abstract: An active vanadium dioxide integrated metasurface offering broadband transmitted terahertz wave modulation with large modulation-depth under electrical control is demonstrated. The device consists of metal bias-lines arranged with grid-structure patterned vanadium dioxide (VO2) film on sapphire substrate. Amplitude transmission is continuously tuned from more than 78% to 28% or lower in the frequency range from 0.3 THz to 1.0 THz, by means of electrical bias at temperature of 68 °C. The physical mechanism underlying the device's electrical tunability is investigated and found to be attributed to the ohmic heating. The developed device possessing over 87% modulation depth with 0.7 THz frequency band is expected to have many potential applications in THz regime such as tunable THz attenuator.

Enhanced photoresponsivity of the MoS 2 -GaN heterojunction diode via the piezo-phototronic effect

Abstract: Combining layered MoS2 flakes with conventional 3D semiconductors is a feasible route to fabricate high-quality heterojunction devices by harnessing the advantages of both materials. Here, we present a pressure-modulated heterojunction photodiode that is composed of an n-type multilayer MoS2 and a p-type GaN film via the piezo-phototronic effect. Under the illumination of 365 nm incident light, a strong photoresponse is observed with response and recovery times of ~66 and 74 ms, respectively. Under a pressure of 258 MPa, the photoresponsivity of this photodiode can be tuned by the piezo-phototronic effect arising from the GaN film to ~3.5 times. Because of the lowered junction barrier with an applied external pressure (strain), more photogenerated carriers can successfully pass through the junction area without recombination, which results in an enhancement effect. This work provides a possible path for the implementation of high-performance electronic and optoelectronic devices that are based on hybrid heterostructures via human interfacing. A device that combines the advantages of both conventional and modern atom-thick semiconductors has been created. Two-dimensional materials have a wide range of exotic electronic properties that could lead to new generation of electronic devices. However, achieving the broadest diversity of functionality will probably necessitate combing these flat materials with conventional semiconductors. Zhong Lin Wang from the Beijing Institute of Nanoenergy and Nanosystems and colleagues created a photodetector whose response can be tuned by applying pressure. They stacked two-dimensional molybdenum disulfide onto a thin film of gallium nitride to create a diode that generates an electrical signal on exposure to light with a wavelength of 365 nanometers. The team showed that the photoresponsivity could be boosted by a factor of 3.5 when an external pressure was applied. Here, we present a pressure-modulated heterojunction photodiode composed of n-type multilayer MoS2 and p-type GaN film by piezo-phototronic effect. Under the illumination of 365 nm incident light, strong photo-response is observed with a response time and recovery time of ~66 and 74 ms, respectively. Upon the pressure of 258 MPa, the photoresponsivity of this photodiode can be enhanced for about 3.5 times by piezo-phototronic effect arising from the GaN film. Due to the lowered junction barrier upon applying an external pressure (strain), more photo-generated carriers can successfully pass through the junction area without recombination, resulting in the enhancement effect.

Electrical dynamic modulation of THz radiation based on superconducting metamaterials

Abstract: We demonstrate an electrically tunable superconducting metamaterial capable of modulating terahertz waves dynamically. The device is based on electromagnetically induced transparency-like metamaterials, and the maximum modulation depth reaches 79.8% in the transmission window. Controlled by an electrical sinusoidal signal, such a device could achieve a modulation speed of approximately 1 MHz. The superior property and simplicity of design make this device promising for the development of high performance THz systems.

Demonstration of measuring sea fog with an SNSPD-based Lidar system.

Abstract: The monitor of sea fogs become more important with the rapid development of marine activities. Remote sensing through laser is an effective tool for monitoring sea fogs, but still challengeable for large distance. We demonstrated a Long-distance Lidar for sea fog with superconducting nanowire single-photon detector (SNSPD), which extended the ranging area to a 180-km diameter area. The system, which was verified by using a benchmark distance measurement of a known island, is applied to the Mie scattering weather prediction Lidar system. The fog echo signal distribution in the range of 42.3∼63.5 km and 53.2∼74.2 km was obtained by the Lidar system. Then the fog concentration and the velocity of the fog were deduced from the distribution, which is consistent with the weather prediction. The height of the sea fog is about two hundred meter while the visibility at this height is about 90 km due to the Earth’s radius of curvature. Therefore, the capability of this SNSPD-based Lidar was close to the theoretical limit for sea fog measurements for extremely high signal-to-noise ratio of SNSPD.

Accuracy analysis and improvement of visible light positioning based on VLC system using orthogonal frequency division multiple access

Abstract: In this paper, we proposed a system that realized simultaneously visible light positioning (VLP) and visible light communications (VLC) in the same band by using orthogonal frequency division multiple access (OFDMA). This system used the power of data sequence as the metric to estimate the transmission distances and consequently the receiver’s position, without deteriorating the VLC’s throughput. We theoretically analyzed the positioning errors in both overdetermined and determined VLP systems. In overdetermined VLP system, optimal selection of master light-emitting diode (LED) avoided the fluctuation of positioning error. Excluding the LED with longest transmission distance changed the overdetermined VLP system to determined VLP system, and reduced the positioning error. The power allocation scheme reduced further the positioning error in determined VLP system. This method was fast and effective. The well-matched theoretical and Monte-Carlo (MC) simulation results validated our proposed VLP based on VLC system using OFDMA.

Tunable electromagnetically induced transparency from a superconducting terahertz metamaterial

Abstract: We demonstrate in this paper the tunable electromagnetically induced transparency (EIT) made from a superconducting (SC) niobium nitride (NbN) film induced by an intense terahertz (THz) field. As the variation of the incident THz field alters the intrinsic ohmic loss of the SC NbN film, the field-dependent transmittance is observed. To elaborate the role of the bright and dark modes, a hybrid coupling model is introduced to fit the experimental transmission spectra and extract the characteristic parameters of each mode. It is shown that the resonator for the bright mode is altered greatly due to strong direct coupling to the incident intense THz field, whereas the dark mode resonator has little interaction with the incident THz field via a weak near-filed coupling to the bright-mode resonator. This implies that we can partially control a mode or a part of metamaterial by introducing the intense THz field, which offers an effective manner to selectively control the electromagnetic property of the metamater...

Translational plasma stomatology: applications of cold atmospheric plasmas in dentistry and their extension

Abstract: In recent years, translational plasma medicine (TPM), as a novel application area of plasmas, has attracted much attention of experts from both academic and clinical fields. State-of-the-art of the lab-scale research and clinical trials of the cold atmospheric plasmas (CAPs) in the stomatology are reviewed in detail from the direct and indirect applications of the CAPs. Based on the discussions concerning the relationship between the plasma stomatology and the plasma medicine, it is indicated that it would be an important reference for promoting the TPM starting from the fundamental and application studies in the field of dentistry, which is also one of the most three promising application fields of plasma medicine.

Cocatalyst-Free Hybrid Ionic Liquid (IL)-Based Porous Materials for Efficient Synthesis of Cyclic Carbonates through a Cooperative Activation Pathway.

Abstract: Cocatalyst-free ionic liquid (IL)-based porous polymers (Px-Vy-OHzR) functionalized with an intermolecular hydroxyl group were prepared by means of radical copolymerization of 1-butyl-3-vinylimidazolium bromide, (4-vinylphenyl)methanol (VBzOH), and divinylbenzene (DVB) under solvothermal conditions. As the ratio of 4-vinylphenylmethanol in the initial mixture increased, the content of the hydroxyl groups in the polymer increased from 3.35 to 5.35 mmol g−1 and the Brunauer–Emmett–Teller (BET) surface area of the polymer decreased sharply from 365 to 2.5 m2 g−1. In the carbonation of CO2 and epoxides, the turnover frequency (TOF) of Px-Vy-OHzR increased gradually from 25 to 67 h−1 as the OH ratio increased irrespective of the sharp decrease in BET surface area, which suggests the existence of a cooperative activation effect between OH and ILs. To obtain a high OH content while still maintaining a high BET surface area, hybrid porous materials (SBA-[VxOHy]R-n) were prepared by means of copolymerization of 1-ethyl-3-vinylimidazolium bromide and 4-vinylphenylmethanol in the mesopores of SBA-15. SBA-[VxOHy]R-n was more active than its polymer counterpart (TOF: 188 versus 71 h−1) in the cycloaddition of CO2 with propyl oxide owing to the combined effect of the high BET surface area and the high OH content. The hybridization of mesoporous materials with polymers represents an efficient strategy for the preparation of high-performance solid catalysts for chemical transformations.

Cooperative Activation of Cobalt-Salen Complexes for Epoxide Hydration Promoted on Flexible Porous Organic Frameworks

Abstract: Developing solid catalysts with multiple active sites working cooperatively is desirable for efficient chemical transformations. However, most solid catalysts are rigid and impede the cooperation between their spatially isolated active sites. Two flexible porous organic frameworks (POFs) with integrated Co(salen) as active sites have been successfully synthesized for mimicking the cooperative modes of enzymes. The POFs exhibit second-order rate dependence on Co(salen) concentration in the network and afford much higher TOF (3300 versus 2670 h-1 ) than the homogeneous counterpart in the hydration of propylene epoxide. POFs with a flexible network thus not only facilitate but also enhance the cooperation of nearby Co(salen). Moreover, POFs could catalyze oversized substrates, have a wide substrate scope, and exhibit high stability.

Homoharringtonine targets Smad3 and TGF-β pathway to inhibit the proliferation of acute myeloid leukemia cells

Abstract: // Jian Chen 1, 2, * , Qitian Mu 1, 2, 3, * , Xia Li 1, 2, * , Xiufeng Yin 1, 2 , Mengxia Yu 1, 2 , Jing Jin 1, 2 , Chenying Li 1, 2 , Yile Zhou 1, 2 , Jiani Zhou 1, 2, 4 , Shanshan Suo 1, 2 , Demin Lu 1, 2 and Jie Jin 1, 2 1 Department of Hematology, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, China 2 Institute of Hematology, Zhejiang University, Hangzhou, China 3 Laboratory of Stem Cell Transplantation, Ningbo First Hospital, Zhejiang, China 4 Hematology Department of Ningbo Medical Center Lihuili Estern Hospital, Ningbo, China * These authors contributed equally to this work Correspondence to: Jie Jin, email: zjuhematology@163.com Keywords: homoharringtonine, smad3, TGF-β, acute myeloid leukemia Received: April 04, 2016 Accepted: March 29, 2017 Published: April 08, 2017 ABSTRACT Homoharringtonine (HHT) has long and widely been used in China for the treatment of acute myeloid leukemia (AML), the clinical therapeutic effect is significant but the working mechanism is poorly understood. The purpose of this study is to screen the possible target for HHT with virtual screening and verify the findings by cell experiments. Software including Autodock, Python, and MGL tools were used, with HHT being the ligand and proteins from PI3K-Akt pathway, Jak-stat pathway, TGF-β pathway and NK-κB pathway as the receptors. Human AML cell lines including U937, KG-1, THP-1 were cultured and used as the experiment cell lines. MTT assay was used for proliferation detection, flowcytometry was used to detect apoptosis and cell cycle arrest upon HHT functioning, western blotting was used to detect the protein level changes, viral shRNA transfection was used to suppress the expression level of the target protein candidate, and viral mRNA transfection was used for over-expression. Virtual screening revealed that smad3 from TGF-β pathway might be the candidate for HHT binding. In AML cell line U937 and KG-1, HHT can induce the Ser423/425 phosphorylation of smad3, and this phosphorylation can subsequently activate the TGF-β pathway, causing cell cycle arrest at G1 phase in U937 cells and apoptosis in KG-1 cells, knockdown of smad3 can impair the sensitivity of U937 cell to HHT, and over-expression of smad3 can re-establish the sensitivity in both cell lines. We conclude that smad3 is the probable target protein of HHT and plays an important role in the functioning mechanism of HHT.

Terahertz Spectroscopy of Dilute Gases Using Bi 2 Sr 2 CaCu 2 O 8 + δ Intrinsic Josephson-Junction Stacks

Abstract: Detection and imaging using light at terahertz frequencies continues to be a topic of keen interest for numerous applications. Recent investigations have shown that stacks of natural Josephson junctions in cuprate superconductors are suitable emitters of THz radiation; now our attention turns to effective use of such a source. Using two setups, one featuring bolometric detection and the other heterodyne, the authors achieve results respectively comparable to those for time-domain spectroscopy and systems based on quantum cascade lasers. These findings indicate that their setups are in fact suitable for gas sensing in environmental monitoring.

Prognostic impact of MYH9 expression on patients with acute myeloid leukemia.

Abstract: // Mengxia Yu 1, 2, 3, * , Jinghan Wang 1, 2, 3, * , Zhijuan Zhu 1, 2, 3, 4, * , Chao Hu 1, 2, 3 , Qiuling Ma 1, 2, 3, 5 , Xia Li 1, 2, 3 , Xiufeng Yin 1, 2, 3 , Jiansong Huang 1, 2, 3 , Ting Zhang 1, 2, 3 , Zhixin Ma 1, 2, 3 , Yile Zhou 1, 2, 3 , Chenying Li 1, 2, 3 , Feifei Chen 1, 2, 3 , Jian Chen 1, 2, 3 , Yungui Wang 1, 2, 3 , Hanzhang Pan 1, 2, 3 , Dongmei Wang 1, 2, 3 , Jie Jin 1, 2, 3 1 Department of Hematology, The First Affiliated Hospital, Zhejiang University College of Medicine, Hangzhou, China 2 Institute of Hematology, Zhejiang University, Hangzhou, China 3 Key Laboratory of Hematologic Malignancies, Diagnosis and Treatment, Zhejiang, Hangzhou, China 4 Department of Hematology, Fujian Medical University Union Hospital, Fuzhou, China 5 Department of Hematology, The Second Affiliated Hospital of Henan University of Traditional Chinese Medicine, Zhengzhou, China * These authors are contributed equally to this work Correspondence to: Jie Jin, email: zjuhematology@163.com Keywords: MYH9, acute myeloid leukemia, prognosis Received: March 14, 2016 Accepted: May 10, 2016 Published: July 15, 2016 ABSTRACT MYH9 expression has previously been demonstrated as an independent predictor of clinical outcome in solid tumors. However, the prognostic relevance of MYH9 expression in acute myeloid leukemia is still unclear. Here, we found high MYH9 expressers were seen more frequently in females and more frequently in M4 morphology. We also found high MYH9 expressers had lower percentage of bone marrow blasts. In addition, overexpression of MYH9 was associated with an inferior overall survival. Notably, distinct microRNA signatures were seen in high MYH9 expressers. These results were also validated in an independent cohort of AML patients using the published data. In conclusion, gene of MYH9 expression might serve as a reliable predictor for overall survival in AML patients.

Characteristics of triboelectrification on dielectric surfaces contacted with a liquid metal in different gases

Abstract: Triboelectric nanogenerators attract more and more research attention, for their high efficiency, low fabrication cost, and high flexibility. However, the mechanism about triboelectrification remains highly debated. In this work, we constructed a liquid-metal based triboelectric nanogenerator (LM-TENG) and investigated the influence of the gas atmosphere on the triboelectrification between the liquid metal and the dielectric materials, such as PTFE, Kapton, and Nylon. It was found that the dielectric materials were negatively charged on contact with the liquid metal in ambient air. But in the nitrogen conditions, the polarity of the charges was reversed. Oxygen was excluded, which is responsible for the polarity reversal in contact electrification. Based on X-ray photoelectron spectroscopy, energy-dispersive X-ray, and SKFM data, a possible mechanism was proposed.

Association Analysis of the MHC in Lupus Nephritis.

Abstract: Lupus nephritis (LN) is one of the most prevalent and serious complications of SLE, with significant effects on patient and renal survival. Although a large number of genetic variants associated with SLE have been identified, biomarkers that correlate with LN are extremely limited. In this study, we performed a comprehensive sequencing analysis of the whole MHC region in 1331 patients with LN and 1296 healthy controls and validated the independent associations in another 950 patients with LN and 1000 controls. We discovered five independent risk variants for LN within the MHC region, including HLA-DRβ1 amino acid 11 (Pomnibus<0.001), HLA-DQβ1 amino acid 45 (P<0.001; odds ratio, 0.58; 95% confidence interval, 0.52 to 0.65), HLA-A amino acid 156 (Pomnibus<0.001), HLA-DPβ1 amino acid 76 (Pomnibus<0.001), and a missense variant in PRRC2A (rs114580964; P<0.001; odds ratio, 0.38; 95% confidence interval, 0.30 to 0.49) at genome-wide significance. These data implicate aberrant peptide presentation by MHC classes 1 and 2 molecules and sex hormone modulation in the development of LN.

Pressureless densification, microstructure tailoring and properties of Ta0.8Hf0.2C-based composites

Abstract: Ta0.8Hf0.2C (TH) ceramics are desirable for applications in ultra-high temperature environments, but they are difficult to be sintered pressurelessly. TH ceramics were densified up to 98.8% from commercial powders via pressureless sintering (PLS) at 2473 K. SiC was introduced as secondary phase to tailor microstructures and improve properties of TH. The influence of SiC volume fraction on the densification, microstructure evolution and room-temperature properties of TH-based ceramics were examined. Average grain size of TH was refined from 13.6 down to 2.0 μm. 10 vol% SiC addition contributed to densification of Ta0.8Hf0.2C-SiC (THS) composites with a relative density of 99.6%. The mechanical properties of THS were fairly good, and thermal properties of sintered THS displayed a remarkable improvement compared with TH: the coefficient of thermal expansion (CTE) showed a reduction of 8.6% while the thermal conductivity increased from 18.6 to 41.5 W/m K.

Upregulation of miR-223 in the rat liver inhibits proliferation of hepatocytes under simulated microgravity.

Abstract: Long-term spaceflight affects numerous organ systems in the body, including metabolic dysfunction. Recently, ample evidence has demonstrated that the liver is a vulnerable organ during spaceflight. However, the changes in hepatocyte proliferation and cell cycle control under microgravity remain largely unexplored. In the present study, we first confirmed that the serum levels of aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase, biochemical markers of liver function, were altered in rats under tail suspension (TS) conditions to simulate microgravity, as shown in previous reports. Next, we demonstrated that the cell proliferation activity, determined by Ki67, PCNA and PH3, was significantly decreased at the different TS time points (TS for 14, 28 and 42 days) compared with that in the control group. Consistently, the positive cell cycle regulators Ccna2, Ccnd1, Cdk1, Cdk2 and cyclin D3 were also significantly decreased in the TS groups as shown by quantitative real-time PCR and western blotting analysis. Subsequent analysis revealed that the aberrant hepatocyte proliferation inhibition under simulated microgravity was associated with the upregulation of miR-223 in the liver. We further found that miR-223 inhibited the proliferation of Hepa1-6 cells and identified CDK2 and CUL1 as its direct targets. In addition, the decreased expression of CDK2 and CUL1 was negatively correlated with the level of p27 in vitro and in vivo, which may have been responsible for retarding hepatocyte proliferation. Collectively, these data indicate that upregulation of miR-223 was associated with the inhibition of liver cell growth and reveal the role of miR-223 in rat hepatocyte proliferation disorders and the pathophysiological process under simulated microgravity.

Antiferromagnetic Kondo lattice compound CePt3P.

Abstract: A new ternary platinum phosphide CePt3P was synthesized and characterized by means of magnetic, thermodynamic and transport measurements. The compound crystallizes in an antiperovskite tetragonal structure similar to that in the canonical family of platinum-based superconductors APt3P (A = Sr, Ca, La) and closely related to the noncentrosymmetric heavy fermion superconductor CePt3Si. In contrast to all the superconducting counterparts, however, no superconductivity is observed in CePt3P down to 0.5 K. Instead, CePt3P displays a coexistence of antiferromagnetic ordering, Kondo effect and crystalline electric field effect. A field-induced spin-flop transition is observed below the magnetic ordering temperature TN1 of 3.0 K while the Kondo temperature is of similar magnitude as TN1. The obtained Sommerfeld coefficient of electronic specific heat is γCe = 86 mJ/mol·K2 indicating that CePt3P is a moderately correlated antiferromagnetic Kondo lattice compound.

Practical dual-band terahertz imaging system.

Abstract: This paper introduces a dual-band terahertz imaging system as a potential product for nondestructive testing using heterodyne detectors and continuous-wave sources. The operating frequencies of the system are 110.4 and 220.8 GHz. Multiband fusion technology combines the advantages of the greater spatial resolution of the high-frequency band and the enhanced sensitivity of the low-frequency band to improve the detection ability of the system. Additionally, the interference cancellation technology is used to obtain a superior image quality. The spatial resolution of this system was approximately 3 mm. The results show that the system can be used for bonding quality and embedded defect detection in radomes and foam materials adhered to metal plates in aircrafts.

A broadband reflective-type half-wave plate employing optical feedbacks.

Abstract: We propose and demonstrate a type of a broadband half-wave plate that operates in the reflective mode. It consists of a metal grating embedded in a dielectric slab and placed on top of a grounded metal surface. We theoretically show that owing to the optical feedback effect which originates from the wave reflections at the air-dielectric interface, the proposed half-wave plate exhibits a broadened and flattened response when comparing to the case where the feedback effect is absent. Such a prediction is validated using both numerical and experimental works carried out on a half-wave plate designed at 10 GHz. Moreover, our theoretical analysis also reveals that the half-wave plate has an interesting feature of broad angular response. Taking advantage of these features, we experimentally demonstrate that the proposed device can function as a freely tunable linear polarization converter with polarization conversion residues less than −20 dB in a wide frequency band, under the condition that the incident angle is as large as 45 degrees.

Self-Mixing Spectra of Terahertz Emitters Based on Bi2Sr2CaCu2O8+δ Intrinsic Josephson-Junction Stacks

Abstract: Developing technology to exploit the ``THz window'' of the electromagnetic spectrum continues to be a major research theme. Stacks of intrinsic Josephson junctions in a cuprate superconductor are a good source of THz photons; with them, one can even imagine a THz laser on a chip. To better understand the purity of this radiation, the authors study the phenomenon of self-mixing, in which the nonlinearity of the Josephson elements leads to two or more nearby THz emission peaks producing signals at the difference frequencies. These results are helpful for synchronizing thousands of Josephson junctions, and may offer a simple method for evaluating the coherence of their THz emission.

Visible light positioning and communication cooperative systems

Abstract: A cooperative system for visible light positioning (VLP) and visible light communication (VLC) is proposed based on the spread-spectrum plugin of optical identification (OPID). By keeping the existing VLC frame structure untouched, two different implementation schemes were designed by adding the location information field into the communication information field for VLP applications. It is deemed to be a good solution to overcome the mutual exclusion between VLP and VLC systems.