Publications by authors named "Weihua Gu"

24 Publications

  • Page 1 of 1

Flexible and transparent silver nanowires/biopolymer film for high-efficient electromagnetic interference shielding.

J Colloid Interface Sci 2021 Sep 1;607(Pt 1):89-99. Epub 2021 Sep 1.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, PR China. Electronic address:

Flexible and transparent conductive films are highly desirable in some optoelectronic devices, such as smart windows, touch panels, as well as displays and electromagnetic protection field. Silver nanowire (Ag NW) has been considered as the best material to replace indium tin oxide (ITO) to fabricate flexible transparent electromagnetic interference (EMI) shielding films due to its superior comprehensive performance. However, the common substrates supporting Ag NWs require surface modification to enhance the adhesion with Ag NWs. In this work, a flexible and transparent Ag NWs EMI shielding film with sandwich structure through a facile rod-coating method, wherein Ag NWs network were embedded between biodegradable gelatin-based substrate and cover layer. The interfacial adhesion between Ag NWs and gelatin-based layers was enhanced by hydrogen-bonding interaction and swelling effect without any pretreatment. The shielding effectiveness (SE) of the G/Ag NW/G (G represents gelatin-based layer) film reaches 37.74 dB at X band with an optical transmittance of 72.0 %. What's more, the flexible gelatin-based layer and encapsulated structure endow the resultant G/Ag NW/G film integrating excellent mechanical properties, reliable durability, antioxidation, as well as anti-freezing performance. This work paves a new way for fabricating flexible transparent EMI shielding films.
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http://dx.doi.org/10.1016/j.jcis.2021.08.190DOI Listing
September 2021

A breathable and flexible fiber cloth based on cellulose/polyaniline cellular membrane for microwave shielding and absorbing applications.

J Colloid Interface Sci 2021 Jul 22;605:193-203. Epub 2021 Jul 22.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, PR China. Electronic address:

High-performance electromagnetic (EM) wave absorption and shielding materials integrating with flexibility, air permeability, and anti-fatigue characteristics are of great potential in portable and wearable electronics. These materials usually prepared by depositing metal or alloy coatings on fabrics. However, the shortcomings of heavy weight and easy corrosion hamper its application. In this work, the cellulose nanofiber (CF) fabric was prepared by electrospinning technology. Then, conductive polyaniline (PANI) was deposited on the CF surface via a facile in-situ polymerization process. The interweaving cellulose/polyaniline nanofiber (CPF) composite constructs a conductive network, and the electrical conductivity can be adjusted by polymerization time. Benefiting from optimal impedance matching, strong conductive loss, as well as interfacial polarization, the CPF possesses excellent EM absorption performance. The minimum reflection loss (RL) value is -49.24 dB, and the effective absorption bandwidth (RL < -10 dB, f) reaches 6.90 GHz. Furthermore, the CPF also exhibits outstanding electromagnetic interference (EMI) shielding capability with shielding efficiency (SE) of 34.93 dB in the whole X band. Most importantly, the lightweight CPF fabrics have the merits of mechanical flexibility, breathability and wash resistance, which is highly applicable for wearable devices.
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http://dx.doi.org/10.1016/j.jcis.2021.07.085DOI Listing
July 2021

Environmentally Friendly and Multifunctional Shaddock Peel-Based Carbon Aerogel for Thermal-Insulation and Microwave Absorption.

Nanomicro Lett 2021 Apr 5;13(1):102. Epub 2021 Apr 5.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, People's Republic of China.

Highlights: The eco-friendly shaddock peel-derived carbon aerogels were prepared by a freeze-drying method. Multiple functions such as thermal insulation, compression resistance and microwave absorption can be integrated into one material-carbon aerogel. Novel computer simulation technology strategy was selected to simulate significant radar cross-sectional reduction values under real far field condition. . Eco-friendly electromagnetic wave absorbing materials with excellent thermal infrared stealth property, heat-insulating ability and compression resistance are highly attractive in practical applications. Meeting the aforesaid requirements simultaneously is a formidable challenge. Herein, ultra-light carbon aerogels were fabricated via fresh shaddock peel by facile freeze-drying method and calcination process, forming porous network architecture. With the heating platform temperature of 70 °C, the upper surface temperatures of the as-prepared carbon aerogel present a slow upward trend. The color of the sample surface in thermal infrared images is similar to that of the surroundings. With the maximum compressive stress of 2.435 kPa, the carbon aerogels can provide favorable endurance. The shaddock peel-based carbon aerogels possess the minimum reflection loss value (RL) of - 29.50 dB in X band. Meanwhile, the effective absorption bandwidth covers 5.80 GHz at a relatively thin thickness of only 1.7 mm. With the detection theta of 0°, the maximum radar cross-sectional (RCS) reduction values of 16.28 dB m can be achieved. Theoretical simulations of RCS have aroused extensive interest owing to their ingenious design and time-saving feature. This work paves the way for preparing multi-functional microwave absorbers derived from biomass raw materials under the guidance of RCS simulations.
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http://dx.doi.org/10.1007/s40820-021-00635-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8021664PMC
April 2021

Polyimide-Based Foams: Fabrication and Multifunctional Applications.

ACS Appl Mater Interfaces 2020 Oct 16;12(43):48246-48258. Epub 2020 Oct 16.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, P. R. China.

Because of their unique three-dimensional cellular structure and intrinsic properties, polyimide foam materials have bright prospects for development in multiple functional equipment, which arouses extensive concern. In this Spotlight on Applications, several typical fabrication methods of polyimide foams and the related synthesis mechanism have been systematically described. The advantages and disadvantages of the preparation methods have been compared with each other. Representative functions and the corresponding mechanism models have been concluded, which involve thermal, mechanical, sensing, electromagnetic, environmental, and electrical fields. In the end, the severe tasks and challenges of polyimide foam materials have been summarized, and their promising future development is worth expecting.
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http://dx.doi.org/10.1021/acsami.0c15771DOI Listing
October 2020

Co-pyrolysis of monobasic potassium phosphate and plastic processing sludge: Characteristics and environmental risks of potentially toxic elements.

Ecotoxicol Environ Saf 2021 Jan 9;208:111434. Epub 2020 Oct 9.

WEEE Research Centre of Shanghai Polytechnic University, Shanghai 201209, China.

A high concentration of potentially toxic elements (PTEs) can be frequently observed in the plastic processing sludge (PPS), thereby restricting its environmental applications. The main objective of this study was to investigate the effects of the co-pyrolysis of PPS and KHPO (0, 5, 10 and 20 wt%) on the characteristics and environmental risks associated with the PTEs in PPS and derived chars. General characteristic analysis revealed that the char yield, ash content, pH, and particle size of the chars prepared with KHPO were greater than those of the char prepared without KHPO by 3.13-4.89 wt%, 2.95-4.4 wt%, 0.77-0.93, and 9.64-30.07 µm, respectively. The results of sequential extraction indicated that co-pyrolysis with KHPO could considerably increase the distribution of PTEs in the F4 fraction (non-bioavailable) in PPS by 1.30-65.90% when compared with that obtained via co-pyrolysis with 5 wt% of KHPO. The toxic leaching tests indicated that the leaching concentrations of Cr, Ni, Cu, Zn, Cd, and Pb in the char prepared without KHPO decreased to different extents when PPS was subjected to co-pyrolysis with KHPO, especially in case of co-pyrolysis with 5 wt% of KHPO. The range of decrease was 26.40-88.34%. However, in case of Cu, Zn, and Pb, the leaching concentration of the chars prepared with more than 10 wt% of KHPO increased owing to the decomposition of (Cu Zn)PbVO(OH) in an acidic environment. The results obtained using Hakanson's equations revealed that the potential ecological risk associated with the PTEs in chars obtained by co-pyrolysis with KHPO decreased, with a minimum decrease of 38.17%. In addition, the risk level associated with PPS reduced from considerable to low after co-pyrolysis with KHPO. The observations of this study imply that the co-pyrolysis of PPS with KHPO can be a promising treatment for PTE immobilization.
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http://dx.doi.org/10.1016/j.ecoenv.2020.111434DOI Listing
January 2021

Extending effective microwave absorbing bandwidth of CoNi bimetallic alloy derived from binary hydroxides.

Sci Rep 2020 Sep 29;10(1):16044. Epub 2020 Sep 29.

School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, People's Republic of China.

Effectively broadening microwave absorbing frequency of pure magnetic substances remains a huge challenge. Herein, micro-perspective structures can be controlled through a calcination route. Satisfactorily, the composites prepared at the calcination temperature of 900 °C exhibit excellent microwave attenuation performance with a broad working frequency and appropriate paraffin filling ratio. Remarkably, the composites can reach an extremely high reflection loss (RL) value of - 49.79 dB, and the extended effective working frequency range (RL < - 10 dB) of 6.84 GHz can also be obtained. Superb magnetic loss, admirable dielectric loss, sufficient dipole polarization, as well as superior impedance matching should be band together for obtaining ideal microwave absorbers. The CoNi hydroxides derived bimatallic alloy composites were fabricated via a cost-effective and facile synthesis process, and this work aroused inspirations of designing high-performance microwave absorbers for mataining the sustainable development.
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http://dx.doi.org/10.1038/s41598-020-73161-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7524764PMC
September 2020

Confining Tiny MoO Clusters into Reduced Graphene Oxide for Highly Efficient Low Frequency Microwave Absorption.

Small 2020 Jul 10;16(30):e2001686. Epub 2020 Jun 10.

School of Materials Science and Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore.

Herein, a supermolecular-scale cage-confinement pyrolysis strategy is proposed to build two dielectric electromagnetic wave absorbents, in which MoO nanoparticles are sandwiched uniformly between porous carbon shells and reduced graphene oxide (RGO). Both sandwich structures are derived from hybrid hydrogels doped by two different crosslinkers (with/without oxygen bridge), which can precisely confine Mo source (e.g., PMo ). Without adding magnetic components, both absorbents exhibit excellent low frequency absorption performance in combination with electrically tunable ability and enhanced reflection loss value, which is superior over other relative 2D dielectric absorbers and satisfies the requirements of portable electronics. Notably, introducing oxygen bridges in the crosslinker generates a more stable confining configuration, which in turn renders its corresponding derivative exhibiting an extra multifrequency electromagnetic wave absorption trait. The intrinsic electromagnetic wave adjustment mechanism of the ternary hybrid absorbent is also explored. The result reveals that the elevated electromagnetic wave absorbing property is attributed to moderate attenuation constant and glorious impendence matching. The cage-confinement pyrolysis route to fabricate 2D MoO -based dielectric electromagnetic wave absorbents opens a new path for the design of electromagnetic wave absorbents used in multi/low frequency.
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http://dx.doi.org/10.1002/smll.202001686DOI Listing
July 2020

Multifunctional Bulk Hybrid Foam for Infrared Stealth, Thermal Insulation, and Microwave Absorption.

ACS Appl Mater Interfaces 2020 Jun 12;12(25):28727-28737. Epub 2020 Jun 12.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, P. R. China.

Taking serious microwave pollution issues and the complex application environment into consideration, it is quite urgent to integrate several functions into one material. Electromagnetic (EM) absorbing materials with multiple functions are highly attractive to next-generation wireless techniques and portable electronic devices. Herein, melamine foam provides a decent platform for the uniform growth of Co-based metal-organic frameworks (MOFs), which bring the as-obtained hybrid foam with three-dimensional porous network structure and combination of dielectric along with magnetic attenuation abilities as advanced materials in multifunctional fields. Remarkably, the relevant microwave absorption (MA) performance of the hybrid foam can reach an extremely high reflection loss value of -59.82 dB. Furthermore, the hybrid foam exhibits excellent infrared stealth and optimiztic heat insulation function, demonstrating the potential in plenty of practical applications. These results may arouse interests and inspirations of the elaborately design and facilely synthesis of high-performance foamlike microwave absorbers with multiple functions.
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http://dx.doi.org/10.1021/acsami.0c09202DOI Listing
June 2020

Environment-Stable CoNi Encapsulation in Stacked Porous Carbon Nanosheets for Enhanced Microwave Absorption.

Nanomicro Lett 2020 Apr 28;12(1):102. Epub 2020 Apr 28.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, 211100, People's Republic of China.

Magnetic/[email protected] carbon composites, derived from metal-organic frameworks (MOFs) with adjustable composition ratio, have attracted wide attention due to their unique magnetoelectric properties. In addition, MOFs-derived porous carbon-based materials can meet the needs of lightweight feature. This paper reports a simple process for synthesizing stacked [email protected] nanosheets derived from CoNi-MOFs nanosheets with multiple interfaces, which is good to the microwave response. The [email protected] with controllable composition can be obtained by adjusting the ratio of Co and Ni. It is supposed that the increased Co content is benefit to the dielectric and magnetic loss. Additionally, the bandwidth of [email protected] nanosheets can take up almost the whole Ku band. Moreover, this composite has better environmental stability in air, which characteristic provides a sustainable potential for the practical application.
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http://dx.doi.org/10.1007/s40820-020-00432-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7770751PMC
April 2020

Migration characteristics of heavy metals during simulated use of secondary products made from recycled e-waste plastic.

J Environ Manage 2020 Jul 17;266:110577. Epub 2020 Apr 17.

WEEE Research Centre of Shanghai Polytechnic University, Shanghai, 201209, China; Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University, Shanghai, 201209, China.

Recycling of plastics from e-waste can conserve resources, however, aging during the use of plastic products can cause the migration of heavy metals in additives. This study presents a methodology for evaluating the risks of heavy metals in waste plastic secondary products during long term use associated with heavy metal migration. The study processes were investigated by: (1) recycling waste plastics and producing secondary products; (2) thermal aging of secondary products; and (3) toxic leaching used to quantitatively analyse the dissolution of heavy metals. Combined with the changes in mechanical properties and microstructure, the effect of aging on the migration of heavy metals was observed. The results showed that the polymer appeared to delaminate, the adhesion of waste plastics to additives decreased, and the mechanical properties clearly decreased after the thermal aging experiment. Leaching experiments showed that the leached concentrations of Ni, Cu, Zn, Pb, and Sb in the three types waste plastic products increased over time. After 8 d of aging, the leached concentrations of Ni, Sb, and Pb exceeded the third, fourth, and third class of the groundwater quality standard, respectively. Specifically, the concentrations of Sb were 141, 289, and 21.1 times higher than the maximum permissible level. Therefore, management hierarchy and safe environmental recycling methods should be developed to reduce the risk of heavy metals in waste plastic secondary products.
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http://dx.doi.org/10.1016/j.jenvman.2020.110577DOI Listing
July 2020

Migration of heavy metal in electronic waste plastics during simulated recycling on a laboratory scale.

Chemosphere 2020 Apr 16;245:125645. Epub 2019 Dec 16.

WEEE Research Centre of Shanghai Polytechnic University, Shanghai, 201209, China; Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University, Shanghai, 201209, China.

Recycling is the primary method to handle electronic waste plastics, however, little attention has been paid to the risk posed by heavy metal migration in waste plastic products. The effect of multistage recycling processes on heavy metal migration and the environmental risk posed by heavy metals during recycling processes were investigated by: (1) Recycling waste plastics and determining the heavy metal contents in secondary products; (2) Using toxic leaching experiments to assess environmental risks of heavy metal migration in secondary products; and (3) Evaluating the effect of recycling processes on the mechanical properties and microstructure of plastics. Results showed that the contents of some harmful heavy metals in processed products exceeded the Safety of Toys Standard. Toxic leaching tests showed that Ni, Cu, Zn, Pb, and Sb migrated outward during secondary products use. With increased recycling times, concentrations of migrated Ni, Cu, Zn, Pb, and Sb increased, and the leached concentrations exceeded the limits stipulated in the Groundwater Quality Standard. Increased recycling times also accelerated waste plastics aging and caused the deterioration of mechanical properties. Furthermore, adhesion between layers decreased, stratification and cracking in polymers appeared, and adhesion of waste plastics to additives decreased. Therefore, the environmental risks of waste plastic recycling should be carefully considered.
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http://dx.doi.org/10.1016/j.chemosphere.2019.125645DOI Listing
April 2020

A biomass derived porous carbon for broadband and lightweight microwave absorption.

Sci Rep 2019 12 9;9(1):18617. Epub 2019 Dec 9.

School of Electronic Science and Engineering, Nanjing University, Nanjing, 210093, P. R. China.

With the continuous progress of science and technology, the traditional magnetic material is no longer able to meet the new complex electromagnetic (EM) environment due to its high bulk density. Therefore, the novel excellent EM absorber with the feature of thin thickness, low density, broad absorption bandwidth and strong absorption intensity is highly desired. Herein, we fabricated a porous carbon with ultrahigh porosity through a facile KOH activation from biomass waste pumpkin seed shell for lightweight EM wave absorption application. By optimizing the porous structures, the strong absorption intensity of -50.55 dB is achieved at thin thickness of 1.85 mm under low filler content of only 10 wt %. More interestingly, a broad frequency bandwidth of 7.4 GHz could cover the whole Ku band. These outstanding microwave absorption performances, couple with low cost ingredients and ease of fabrication process enable the porous carbon framework as the next generation promising candidate for lightweight and remarkable EM absorber.
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http://dx.doi.org/10.1038/s41598-019-54104-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6901585PMC
December 2019

Developmental exposure to lead at environmentally relevant concentrations impaired neurobehavior and NMDAR-dependent BDNF signaling in zebrafish larvae.

Environ Pollut 2020 Feb 21;257:113627. Epub 2019 Nov 21.

WEEE Research Centre of Shanghai Polytechnic University, Shanghai Collaborative Innovation Centre for WEEE Recycling, Shanghai, 201209, China; Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University, Shanghai, 201209, China.

Lead (Pb) is one of the predominant heavy metals in e-waste recycling arears and recognized as a notorious environmental neurotoxic substance. However, whether Pb at environmentally relevant concentrations could cause neurobehavioral alteration and even what kind of signaling pathway Pb exposure would disrupt in zebrafish were not fully uncovered. In the present study, 6 h postfertilization (hpf) zebrafish embryos were exposed to Pb at the concentrations of 0, 5, 10, and 20 μg/L until 144 hpf. Then the neurobehavioral indicators including locomotor, turnings and social behaviors, and the expressions of selected genes concerning brain-derived neurotrophic factor (BDNF) signaling were investigated. The results showed that significant changes were obtained under 20 μg/L Pb exposure. The hypoactivity of zebrafish larvae in locomotor and turning behaviors was induced during the dark period, while hyperactivity was observed in a two-fish social assay during the light period. The significantly downregulation of genes encoding BDNF, its receptor TrkB, and N-methyl-D-aspartate glutamate receptor (NMDAR) suggested the involvement of NMDAR-dependent BDNF signaling pathway. Overall, our study demonstrated that developmental exposure to Pb at environmentally relevant concentrations caused obvious neurobehavioral impairment of zebrafish larvae by disrupting the NMDAR-dependent BDNF signaling, which could exert profound ecological consequences in the real environment.
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http://dx.doi.org/10.1016/j.envpol.2019.113627DOI Listing
February 2020

Improved bioleaching efficiency of metals from waste printed circuit boards by mechanical activation.

Waste Manag 2019 Oct 13;98:21-28. Epub 2019 Aug 13.

WEEE Research Centre of Shanghai Polytechnic University, Shanghai 201209, China; Shanghai Collaborative Innovation Centre for WEEE Recycling, Shanghai 201209, China; Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University, Shanghai 201209, China.

The low bioleaching efficiency of Acidithiobacillus ferrooxidans results in its sparse industrial application for metal extraction from waste printed circuit boards (WPCBs). To improve the bioleaching efficiency of Acidithiobacillus ferrooxidans, we propose the use of mechanical activation to dispose WPCBs prior to performing bioleaching. Response surface methodology (RSM), scanning electron microscope- energy dispersive spectrometer (SEM-EDS), and laser particle size analyzer (LPSA) were used to optimize and analyze the mechanical activation process, respectively. The optimal conditions for mechanical activation was a milling time of 2 h, milling speed of 340 r min, and ball material ratio (w/w) of 10/1; the bioleaching rates of Cu, Ni, and Zn were 94.33%, 90.69%, and 90.78%, respectively. The bioleaching rates of Cu, Ni, and Zn were 74.75%, 70.46%, and 71.05%, respectively, without mechanical activation pretreatment. SEM-EDS and LPSA analyses indicated that mechanical activation could lead to a smaller particle size and expose wrapped metals, thus improving the bioleaching efficiency oyf tyhe metals inside the WPCBs. The electrode potential of the metals was likely changed by the mechanical activation, resulting in an improvement of their bioleaching efficiency. Additionally, the bioleaching rates of Pb, Cr, and Cd after mechanical activation pretreatment were 10.29%, 74.89%, and 54.12%, respectively. Contrastingly, the bioleaching rates of Pb, Cr, and Cd without mechanical activation pretreatment were 5.18%, 59.97%, and 37.12%, respectively. Thereinto, the precipitation of PbSO may result in a decrease of leached Pb. We propose a mechanical activation process for improving the bioleaching efficiency of metals from WPCBs.
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http://dx.doi.org/10.1016/j.wasman.2019.08.013DOI Listing
October 2019

Thermal treatment of liquid crystal display panel scraps: The metals migration and potential environmental risk in solid residue.

Waste Manag 2019 Jul 30;94:49-57. Epub 2019 May 30.

Research Center of Resource Recycling Science and Engineering, Shanghai Polytechnic University, No. 2360 Jinhai Road, Shanghai 201209, PR China; Shanghai Collaborative Innovation Centre for WEEE Recycling, No. 2360 Jinhai Road, Shanghai 201209, PR China.

Thermal treatment has been proved to be an efficient and promising method for organics removal from LCD panels and for resource recycling. Considering with the toxic metals contained in LCD panels and their potential risk, it is necessary to study and evaluate the metals behavior and potential risk associated with the thermal treatment of LCD panels. In this study, the migration and transformation behavior of ten metals (Cr, As, Al, In, Ni, Cu, Zn, Cd, Fe, Sn) in LCD panels were investigated during thermal treatment, as well as their potential environmental risk and leaching toxicity in solid residue were evaluated. Results showed that Cr, Ni, In, Cu and Fe exhibit obvious migration behavior from solid into gas phase/fly ash during thermal treatment, with the maximum migration rate of 52.8%, 54.7%, 37.7%, 30.8%, and 34.9% respectively under the experimental condition. Speciation transformation for the metals of Cr, Ni, In, Cu, Fe and Zn was also observed in solid residue after thermal treatment, which leads to the ecological risk increase of Cu, In and contamination risk increase of Fe. Meanwhile, the leachable concentration and leaching toxicity of Cu and Ni in solid residue showed increasing trend after thermal treatment. The results indicate that attentions should be paid on the emission control of Cr, Ni, In, Cu, Fe during thermal treatment of LCD panel scraps. Environmental risk of Cu, In, Fe and the leaching toxicity of Ni in solid residue after thermal treatment should also be concerned.
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http://dx.doi.org/10.1016/j.wasman.2019.05.037DOI Listing
July 2019

Mesoporous carbon hollow spheres as a light weight microwave absorbing material showing modulating dielectric loss.

Dalton Trans 2019 Jul 11;48(27):10145-10150. Epub 2019 Jun 11.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, P. R. China.

Mesoporous carbon hollow spheres (MCHS), a kind of light weight material, were fabricated by a simple one-pot process. It is confirmed that the addition of tetrapropoxysilane (TPOS) has a distinct influence on their surface area, pore volume, porous structure and microwave absorption properties. The modulation of electromagnetic parameters within the range of 2-18 GHz can be accomplished by adjusting the pore volume of MCHS, resulting in the largest bandwidth of 6.2 GHz and a maximum reflection loss of -38.5 dB at a thickness of 2-3 mm. The enhanced microwave absorption properties are attributed to the outstanding impedance matching and strong dielectric loss. This study provides novel insights into electromagnetic wave absorption by tuning the pore volume structure.
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http://dx.doi.org/10.1039/c9dt01876jDOI Listing
July 2019

Nanofiber network with adjustable nanostructure controlled by PVP content for an excellent microwave absorption.

Sci Rep 2019 Mar 12;9(1):4271. Epub 2019 Mar 12.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing, 210016, P.R. China.

Carbon nanofibers were widely utilized to improve microwave absorption properties since they are a promising lightweight candidate. Adjustable conductive nanostructures of carbon nanofibers were synthesized by electrospinning technique. The conductive network is controlled by the polyvinyl pyrrolidone (PVP) content due to the special hygroscopicity of PVP. The increased adhesive contacts of nanofibers provide more transmission paths for electrons to reduce the effect of air dielectric. Satisfactorily, the carbon nanofibers that carbonized from the polyacrylonitrile (PAN) and PVP (the mass ratio is 6:4) show excellent microwave absorption performance. The minimum reflection loss (RL) value is -51.3 dB at 15.2 GHz and the maximum effective absorption frequency width (<-10 dB) is 5.1 GHz with the matching thickness of only 1.8 mm. Thereby, we believe that this research may offer an effective way to synthesize lightweight carbon nanofibers microwave absorbents.
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http://dx.doi.org/10.1038/s41598-019-38899-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6414720PMC
March 2019

Analyzing freeway crash severity using a Bayesian spatial generalized ordered logit model with conditional autoregressive priors.

Accid Anal Prev 2019 Jun 4;127:87-95. Epub 2019 Mar 4.

School of Traffic and Transportation, Changsha University of Science and Technology, Changsha, Hunan, 410114, PR China. Electronic address:

This study develops a Bayesian spatial generalized ordered logit model with conditional autoregressive priors to examine severity of freeway crashes. Our model can simultaneously account for the ordered nature in discrete crash severity levels and the spatial correlation among adjacent crashes without fixing the thresholds between crash severity levels. The crash data from Kaiyang Freeway, China in 2014 are collected for the analysis, where crash severity levels are defined considering the combination of injury severity, financial loss, and numbers of injuries and deaths. We calibrate the proposed spatial model and compare it with a traditional generalized ordered logit model via Bayesian inference. The superiority of the spatial model is indicated by its better model fit and the statistical significance of the spatial term. Estimation results show that driver type, season, traffic volume and composition, response time for emergency medical services, and crash type have significant effects on crash severity propensity. In addition, vehicle type, season, time of day, weather condition, vertical grade, bridge, traffic volume and composition, and crash type have significant impacts on the threshold between median and severe crash levels. The average marginal effects of the contributing factors on each crash severity level are also calculated. Based on the estimation results, several countermeasures regarding driver education, traffic rule enforcement, vehicle and roadway engineering, and emergency services are proposed to mitigate freeway crash severity.
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http://dx.doi.org/10.1016/j.aap.2019.02.029DOI Listing
June 2019

Pollution analysis of soil polycyclic aromatic hydrocarbons from informal electronic waste dismantling areas in Xinqiao, China.

Waste Manag Res 2019 Apr 8;37(4):394-401. Epub 2019 Feb 8.

1 WEEE Research Centre of Shanghai Polytechnic University, Shanghai, China.

Polycyclic aromatic hydrocarbons (PAHs) are considered to be persistent organic pollutants, which pose a great threat to human health and the surrounding environment. In order to explore the influence of informal electronic waste (e-waste) dismantling activities on inhabitants who live nearby, soil samples were collected from informal e-waste dismantling areas in Xinqiao, China and analysed for 16 United States Environmental Protection Agency (USEPA) priority PAHs. Results indicated that the 16 USEPA priority PAHs were found at all seven sampling locations. Sampling location 3, which was only 10 m away from a residential area, had 1053.69 μg kg of PAHs and seriously exceeded the standard value specified by the Netherlands. The total percents of 4-ring and 5-ring PAHs accounted for 61.74 and 71.70%, respectively, indicating that most of the detected PAHs belonged to high-ring PAHs. The informal e-waste dismantling activities are the major sources of soil PAHs in Xinqiao. Furthermore, the concentration of seven carcinogenic PAHs was 114.76 μg kg and represented a potential health risk to humans. Thereinto, benzo[a]pyrene contributed the most, accounting for more than 50% in these locations. Our results may provide a reference about the influence of informal e-waste dismantling activities on the surrounding inhabitants and suggest that e-waste dismantling activities must be conducted in a formal enterprise which is far away from residential areas.
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http://dx.doi.org/10.1177/0734242X19826369DOI Listing
April 2019

Integrating carbonyl iron with sponge to enable lightweight and dual-frequency absorption.

Nanotechnology 2019 May 23;30(19):195703. Epub 2019 Jan 23.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, People's Republic of China.

In this work, sponge impregnated with iron pentacarbonyl was utilized to obtain a novel composite in which the carbonyl iron (CI) was embedded in a graphitized carbon matrix (CI-C). The CI that results from the thermal pyrolysis of iron pentacarbonyl can homogeneously disperse into the pore structures of the sponge skeleton, which not only improves the stability of the CI, but also modifies the impedance matching character. Moreover, the sponge bulk turns into graphitized carbon during the heat treatment (graphitized catalysis of magnetic metal on carbon at high temperature). Due to the respective strong dissipation ability of CI and the graphitized carbon matrix, the as-prepared CI-C sample exhibits a good microwave absorption performance, including expanding the effective absorption bandwidth and reduced weight, compared to pure CI. Moreover, the sample with 30 wt% paraffin loading not only shows strong reflection loss absorbing ability, but also possesses continuous dual-absorption peaks (9.96 GHz, -38.7 dB, and 13.8 GHz is -37.6 dB). This work not only extends the application of carbonyl iron as a lightweight microwave absorber with dual-absorption peaks but also initiates a new approach for artificially designed carbon-based composites via a simple sponge-impregnation method.
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http://dx.doi.org/10.1088/1361-6528/ab0126DOI Listing
May 2019

Cobalt nanoparticles embedded nitrogen-doped porous graphitized carbon composites with enhanced microwave absorption performance.

J Colloid Interface Sci 2019 Jan 25;533:297-303. Epub 2018 Aug 25.

College of Materials Science and Technology, Nanjing University of Aeronautics and Astronautics, Nanjing 211100, PR China. Electronic address:

For high-efficiency microwave absorption, both of the self loss of materials (dielectric loss and magnetic dissipation) and structural attenuation (multiple scattering, interfacial polarization) play important roles. In addition, the magnetic/dielectric materials combination, and void volume introduction can also contribute to the optimization of impedance matching. Given that, 2D cobalt nanoparticles embedded nitrogen-doped porous graphitized carbon composites ([email protected]) were fabricated via a simple sacrificial templates method, where the CoAl-layered double hydroxide (CoAl-LDH) nanosheets were prepared to hold ZIF-67 and then decomposed during the sintering process. In this work, strong dielectric attenuation, multiple microwave scattering and dielectric polarization, as well as shortened impedance matching all make for the nice microwave absorption performance. This work not only exhibits the importance in materials selection and structure design, but also demonstrates the close relation between matching thickness and response frequency at maximum reflection loss (RL) peak.
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http://dx.doi.org/10.1016/j.jcis.2018.08.083DOI Listing
January 2019

Heavy metals in soil at a waste electrical and electronic equipment processing area in China.

Waste Manag Res 2017 Nov 22;35(11):1183-1191. Epub 2017 Aug 22.

1 WEEE Research Centre of Shanghai Polytechnic University, Shanghai, P.R. China.

For the objective of evaluating the contamination degree of heavy metals and analysing its variation trend in soil at a waste electrical and electronic equipment processing area in Shanghai, China, evaluation methods, which include single factor index method, geo-accumulation index method, comprehensive pollution index method, and potential ecological risk index method, were adopted in this study. The results revealed that the soil at a waste electrical and electronic equipment processing area was polluted by arsenic, cadmium, copper, lead, zinc, and chromium. It also demonstrated that the concentrations of heavy metals were increased over time. Exceptionally, the average value of the metalloid (arsenic) was 73.31 mg kg in 2014, while it was 58.31 mg kg in the first half of 2015, and it was 2.93 times and 2.33 times higher than that of the Chinese Environmental Quality Standard for Soil in 2014 and the first half of 2015, respectively. The sequences of the contamination degree of heavy metals in 2014 and the first half of 2015 were cadmium > lead > copper > chromium > zinc and cadmium > lead > chromium > zinc > copper. From the analysis of the potential ecological risk index method, arsenic and cadmium had higher ecological risk than other heavy metals. The integrated ecological risk index of heavy metals (cadmium, copper, lead, zinc, and chromium) and metalloid (arsenic) was 394.10 in 2014, while it was 656.16 in the first half of 2015, thus documenting a strong ecological risk.
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http://dx.doi.org/10.1177/0734242X17725803DOI Listing
November 2017

Early developmental exposure to pentachlorophenol causes alterations on mRNA expressions of caspase protease family in zebrafish embryos.

Chemosphere 2017 Aug 28;180:141-148. Epub 2017 Mar 28.

Shanghai Collaborative Innovation Centre for WEEE Recycling, WEEE Research Centre of Shanghai Polytechnic University, Shanghai 201209, China.

Caspase proteases play an essential role in cell apoptosis and inflammation, thus matter greatly in animal development and other biological processes. As a ubiquitous environmental pollutant, pentachlorophenol (PCP) is considered to have adverse effects on animal apoptosis during embryonic development, yet the evidence that PCP interfere with caspase genes was seldom reported. To uncover the effects of PCP on caspases expression in early embryos of zebrafish, two concentrations of PCP (5 μg/L and 200 μg/L) were chosen and 14 types of caspase genes at two different developmental stages, 8 h post-fertilization (hpf) and 24 hpf were analyzed. Lower survival and hatching rates, distinct developmental delay and morphological deformities of head and tail were observed. PCP, especially in the high concentration, significantly altered the expressions of most caspase genes. At 8 hpf, PCP had the most significant inductive effects on gene casp8l2 with fold changes (FCs) of 6.87 at 5 μg/L and 4.48 at 200 μg/L, and casp6l1 (with FCs of 3.15/3.69), and inhibitory effects on caspa (with FCs of 0.93/0.53) and caspb (with FCs of 0.99/0.57). At 24 hpf, PCP had the most significant effects on casp6l2, casp9, and caspc. PCP exposure possibly disrupted intrinsic apoptosis pathway considering its effects on casp9 expression. In addition, most caspase genes exhibited higher levels at 24 hpf than 8 hpf except caspc. Our results suggested that PCP had different effects on varied caspase genes, which probably resulting in a profound impact on caspase proteins and apoptosis processes and, ultimately, developmental abnormality.
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http://dx.doi.org/10.1016/j.chemosphere.2017.03.100DOI Listing
August 2017

PSD-95 regulates D1 dopamine receptor resensitization, but not receptor-mediated Gs-protein activation.

Cell Res 2009 May;19(5):612-24

State Key Laboratory of Drug Research, Department of Neuropharmacology, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China.

The present study aims to define the role of postsynaptic density (PSD)-95 in the regulation of dopamine (DA) receptor function. We found that PSD-95 physically associates with either D(1) or D(2) DA receptors in co-transfected HEK-293 cells. Stimulation of DA receptors altered the association between D(1) receptor and PSD-95 in a time-dependent manner. Functional assays indicated that PSD-95 co-expression did not affect D(1) receptor-stimulated cAMP production, Gs-protein activation or receptor desensitization. However, PSD-95 accelerated the recovery of internalized membrane receptors by promoting receptor recycling, thus resulting in enhanced resensitization of internalized D(1) receptors. Our results provide a novel mechanism for regulating DA receptor recycling that may play an important role in postsynaptic DA functional modulation and synaptic neuroplasticity.
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http://dx.doi.org/10.1038/cr.2009.30DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5800406PMC
May 2009
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