Jun Hu

East China University of Science and Technology, Shanghai, Shanghai Shi, China

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Publications (56)96.71 Total impact

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    ABSTRACT: The surface inside the one-dimensional channels of mesoporous SBA-15 was effectively activated by DBD plasma treatment in O2 atmosphere, which promoted the amine modification with both large loading amount (2.56 mmol (APTS)/g(sample)) and high rate (within 2 h). The resulted material also showed a high CO2 adsorption capacity.
    Microporous and Mesoporous Materials 01/2015; 202:16–21. · 3.37 Impact Factor
  • Microporous and Mesoporous Materials 12/2014; 200:159–164. · 3.37 Impact Factor
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    ABSTRACT: Thiazolothiazole-linked porous organic polymers have been synthesized from a facile catalyst-free condensation reaction between aldehydes and dithiooxamide under solvothermal condition. The resultant porous frameworks exhibit a highly selective uptake of CO2 over N2 at ambient conditions.
    Chemical Communications 10/2014; · 6.38 Impact Factor
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    ABSTRACT: Mixed micelle template approach is one of the most promising synthesis methods for hierarchical porous materials. Although considerable research efforts have been made to explore the formation mechanism, an explicit theoretical guidance for appropriately choosing templates is still not available. We found that the phase separation occurring in the mixed micelles would be the key point for the synthesis of hierarchical porous materials. Herein, the pseudo-phase separation theory for the critical micelle concentration (cmc) combining with the Flory-Huggins model for the chain molecular mixture were employed to investigate the properties of mixed surfactant aqueous solution. The cmc values of mixed surfactant solutions were experimentally determined to calculate the Flory-Huggins interaction parameter between two surfactants, χ. When χ is larger than the critical value,χc, the phase separation would occur within the micellar phase, resulting in two types of mixed micelles with different surfactant compositions, and hence different sizes, which could be used as the dual-template to induce bimodal pores with different pore sizes. Therefore, the Flory-Huggins model could be a theoretical basis to judge whether the mixed surfactants were the suitable templates for inducing hierarchical porous materials. We chose cetyltrimethylammonium bromide (CTAB) and n-octylamine (OA) as a testing system. The phase separation behavior of the mixed solutions, as well as the successful synthesis of hierarchical porous materials by this dual-template indicated the feasibility of preparing hierarchical porous materials based on the concept of phase separation of the mixed micelles.
    Langmuir : the ACS journal of surfaces and colloids. 09/2014;
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    ABSTRACT: The world becomes more stringent on keep lowering the sulfur concentrations in fuels. To fulfill this expectation, a new type of magnetic desulfurization adsorbent of Fe3O4@PAA@MOF-199 was designed and fabricated by a facile two-step assembly approach, in which PAA inventively acted like a bridge to incorporate different amounts of the magnetite Fe3O4 into MOF-199 crystal matrix. Fe3O4@PAA@MOF-199s were demonstrated to be efficient adsorbents for the removal of S-compounds of thiophene, benzothiophene (BT) and dibenzothiophene (DBT) from a model fuel, and the sulfur saturated adsorption capacity followed the order of DBT > BT > thiophene. The magnetization of Fe3O4@PAA@MOF-199s insured the adsorbents a good performance in magnetic separation. The relative high adsorption capacity, the separation efficiency, as well as the stable recyclability indicated that magnetic Fe3O4@PAA@MOF-199 would be a promising adsorbent in adsorptive desulfurization.
    RSC Advances 08/2014; · 3.71 Impact Factor
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    ABSTRACT: A porous triazine and carbazole bifunctionalized task-specific polymer has been synthesized via a facile Friedel-Crafts reaction. The resultant porous framework exhibits excellent CO2 uptake (18.0 wt%, 273 K and 1 bar) and good adsorption selectivity for CO2 over N2.
    Chemical Communications 05/2014; · 6.38 Impact Factor
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    ABSTRACT: Through-wall indication of human targets is highly desired in many applications. Generally, human targets behind wall are noncooperative, and rare prior knowledge about the circumstance behind wall could be available. Thus, it requires the ability to indicate human targets with different motions from clutters. To investigate this problem, we first examine the conventional time-domain indication methods, and find that their performances are controlled by the historical pulse number adopted to estimate background, which corresponds to the tap-length from the angle of filter. Then, based on an intermittent mode of human target echoes, we define the optimum tap-length as the shortest tap-length that makes the filter output signal-to-clutter-and-noise ratio reach maximum and develop an adaptive indication method with a gradient tap-length control scheme to search the optimum tap-length. Finally, through-wall experiments with an impulse through-wall radar demonstrate that the proposed method can obtain a good adaptive indication performance on human target with different motions.
    IEEE Geoscience and Remote Sensing Letters 04/2014; 11(5). · 1.82 Impact Factor
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    ABSTRACT: A fully atomistic simulation study is reported to provide mechanistic insight into the superior performance experimentally observed for a polymer membrane (Carta et al., Science, 2013, 339, 303-307). The membrane namely PIM-EA-TB is produced by a shape-persistent ladder polymer of intrinsic microporosity (PIM) with rigid bridged bicyclic ethanoanthracene (EA) and Tröger's base (TB). The simulation reveals that PIM-EA-TB possesses a larger surface area, a higher fraction free volume and a narrower distribution of torsional angles compared to PIM-SBI-TB, which consists of less rigid spirobisindane (SBI). The predicted surface areas of PIM-EA-TB and PIM-SBI-TB are 1168 and 746 m(2) g(-1), close to experimental values of 1120 and 745 m(2) g(-1), respectively. For five gases (CO2, CH4, O2, N2 and H2), the solubility and diffusion coefficients from simulation match well with experimental data, except for H2. The solubility coefficients decrease in the order of CO2 > CH4 > O2 > N2 > H2, while the diffusion coefficients increase following CH4 < CO2 < N2 < O2 < H2. In terms of the separation for CO2/N2, CO2/CH4 and O2/N2 gas pairs, PIM-EA-TB exhibits higher permselectivities than PIM-SBI-TA, in good agreement with experiment. From a microscopic perspective, this simulation study elucidates that the presence of bridged bicyclic units in PIM-EA-TB enhances the rigidity of polymer chains as well as the capability of gas permeation and separation, and the bottom-up insight could facilitate the rational design of new high-performance membranes.
    Physical Chemistry Chemical Physics 02/2014; · 4.20 Impact Factor
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    ABSTRACT: TiO2 microspheres with various amounts of carbon-residue, such as core/shell C@TiO2, hollow neat H-TiO2, and hollow C/TiO2 composites have been obtained via one-pot hydrothermal process. With a thin shell of TiO2 nanoparticles and carbon-residues, the capacity of hollow C/TiO2 composite maintains at 143.3 mAh · g− 1 at 0.5 C (83.5 mA · g− 1) after 100 cycles.
    Chinese Journal of Chemical Engineering. 01/2014;
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    ABSTRACT: Abstract Context: Release of two drugs safely and independently should be necessary in medical or reaction engineering fields to overcome many complex problems such as multi-drug resistance in treatment of disease. Objectives: Core-shell structural microparticles that can load/release two drugs simultaneously are designed and prepared. Materials: The microparticles are composed of mesoporous silica core and hyaluronate (HA)/poly (N-isopropylacrylamide) hybrid gel shell. Methods: The synthesis processes are monitored by powder x-ray diffraction and Fourier transform infrared spectroscopy. The properties of microparticles are characterized by nuclear magnetic resonance, dynamic light scattering and transmission electron microscope methods. Two kinds of drugs are loaded into the mesoporous-core and gel-shell, respectively, and then released under various conditions. Results: The microparticles show uniform spherical shapes with core-shell structures. When temperature is higher than the lower critical solution temperature, the microparticles shrink abruptly and assemble. The drug release rates have been found to depend on the concentration of the microparticle suspensions and pH of the release medium. Discussion: The swellability of the microparticles are controlled by the HA size and gel crosslink density; and the main effect factors on drug releasing behavior are the drug properties and drug diffusion ability. Conclusion: The experimental results confirmed different drugs could be safely loaded into the core-shell structural microparticles and released independently, which might be potential carriers for drugs or catalysts. These microparticles would be expected to make sense for applying in medical or reaction engineering fields.
    Drug Delivery 11/2013; · 2.02 Impact Factor
  • Solid State Sciences 10/2013; · 1.67 Impact Factor
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    ABSTRACT: Fast synthesis of nanosized zeolite is desirable for many industrial applications. An ultrafast synthesis of LTA nanozeolite by the organic-additive-free method in a two-phase segmented fluidic microreactor has been realized. The results reveal that the obtained LTA nanozeolites through microreactor are much smaller and higher crystallinity than those under similar conditions through conventional macroscale batch reactor. By investing various test conditions, such as the crystallization temperature, the flow rate, the microchannel length, and the aging time of gel solution, this two-phase segmented fluidic microreactor system enables us to develop an ultrafast method for nanozeolite production. Particularly, when using a microreactor with the microchannel length of 20 m, it only takes 10 min for the crystallization and no aging process to successfully produce the crystalline LTA nanozeolites at 95 degrees C.
    Journal of Nanoscience and Nanotechnology 08/2013; 13(8):5736-43. · 1.15 Impact Factor
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    ABSTRACT: Adsorption is an effective method for separating CO2 from flue gases. The fixed-bed adsorption and desorption of CO2 on MCM-41 and amine-modified MCM-41 (APTS-MCM-41) were studied. The dual-site Langmuir model, which considered both chemical adsorption and physical adsorption, was used to fit the experimental data. The resulting thermodynamic parameters, such as the saturated adsorption capacity, equilibrium constant, enthalpy and entropy, suggested the feasibility of the CO2 adsorption on APTS-MCM-41, as well as the reality of the adsorption mechanism. A dynamic model based on the linear driving force approximation for the mass transfer was used to describe the adsorption kinetics of CO2. The influences of the operating conditions on the breakthrough curve were investigated using both experimental and theoretical methods. Meanwhile, the impacts of changing values of the axial dispersion coefficient and the mass transfer coefficient were investigated. It showed that the amine-modified mesoporous materials would be a promising sorbent in the future CO2 capture.
    ARCHIVE Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering 1989-1996 (vols 05/2013; 227(2):106-116. · 0.31 Impact Factor
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    ABSTRACT: The thermoresponsive transition behavior of a diblock copolymer consisting of poly(ethylene glycol) methyl ether (mPEG) and poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) in aqueous solutions has been investigated. With a specific composition, the copolymer showed a unique tunable phase transition from no response in acidic media to a soluble-insoluble (S-I) transition in neutral media and an S-I-S transition in basic media either in the presence of salt or for salt-free solutions. The S-I-S transition can be tuned over a wide temperature range even to an S-I type transition just by adding salts. In addition, phase transitions can occur in both pure water and saline solution under practical conditions (30-80 °C), which makes them suitable for a broad range of applications.
    Macromolecular Rapid Communications 02/2013; · 4.93 Impact Factor
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    ABSTRACT: Ultra-wide band (UWB) through wall radar (TWR) is considered as one of the preferred techniques for through-wall human indication due to its good penetration and high range resolution. UWB TWR benefits from its large bandwidth, but the large bandwidth inadvertently results in an issue not substantial in narrowband radars - high timing jitter effect. In typical impulse TWR, timing jitter is mainly caused by the non-ideal sampling clock at the receiver. The fact that impulse TWR employs pulses with very narrow width makes little jitter inaccuracy large enough to degrade the system performance. However, very few studies about the timing jitter in the UWB TWR applications can be found. In this paper, we focus on the impact of timing jitter on the clutter suppression in through-wall human indication. We first model and analyze the timing jitter in impulse TWR. Then, we introduce a simple jitter compensation method based on interpolation and cross correlation with a specified pulse to align the sampled pulses and combat the timing jitter. Finally, we adopt the exponential average background subtraction (EABS) method to suppress clutters. The proposed method is effective to remove the jitter distortion in clutter mitigation, and applicable for real-time applications. Through-wall experiments are presented to verify the proposed method.
    Ultra-Wideband (ICUWB), 2013 IEEE International Conference on; 01/2013
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    ABSTRACT: Gold nanoparticles were prepared in surfactant solutions by reduction of HAuCl4 under UV irradiation without adding extra reductants or other organic substances. The effect of the structure and the property of surfactant on the size and the optical properties of prepared gold nanoparticles were studied. It was found that the longer the alkyl chain of the surfactant, the larger gold particles are obtained. On the other hand, lengthen the geminis spacer benefits the formation of smaller gold particles. The formation of adduct micelles composed of the charged surface active portion of the surfactant molecule and the (AuIIICl4)− ion in cationic surfactant solution serves as the gold source and favors the formation of gold particles with larger sizes. While the repulsion between the (AuIIICl4)− ion and the negative charged surface of anionic surfactant micelle is in favor of the formation of gold nanoparticles with smaller sizes. The nonionic surfactants can also assist the formation of dispersed gold nanoparticles.
    Solid State Sciences 01/2013; 15:17–23. · 1.67 Impact Factor
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    ABSTRACT: This paper presents a time domain, moving target detection (MTD) processing formulation for detecting human motion behind walls. The proposed MTD processing formulation consists of exponential averaging background subtraction, ordered statistics constant false alarm rate detection (OS-CFAR) and binary accumulation. We demonstrate the effectiveness of the MTD processing formulation using data collected by an impulse, ultra-wideband through-wall radar. We also analyze the false alarm and detection rate of human with static standing and radial movement.
    Radar Conference (RADAR), 2013 IEEE; 01/2013
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    ABSTRACT: There are still many false alarms in two-value image after CFAR detection in ultra-wideband through-wall radar. These false alarms can be divided into three categories, namely the isolated noise, target side lobe and random strong clutter false alarms. In order to suppress them, a new target recognition algorithm was presented in this paper; it was made up of binary integration, the hierarchical clustering processing and target tracking. The processing results of measured data show that the algorithm can effectively suppress above false alarms, and achieve accurate information of target number and location.
    Radar Symposium (IRS), 2013 14th International; 01/2013
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    ABSTRACT: A 3D Tröger’s-base-derived microporous organic polymer with a high surface area and good thermal stability was facilely synthesized from a one-pot metal-free polymerization reaction between dimethoxymethane and triaminotriptycene. The obtained material displays excellent CO2 uptake abilities as well as good adsorption selectivity for CO2 over N2. The CO2 storage can reach up to 4.05 mmol g–1 (17.8 wt %) and 2.57 mmol g–1 (11.3 wt %) at 273 K and 298 K, respectively. Moreover, the high selectivity of the polymer toward CO2 over N2 (50.6, 298 K) makes it a promising material for potential application in CO2 separation from flue gas.
    ACS Macro Letters 01/2013; 2:660-663. · 5.24 Impact Factor
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    ABSTRACT: Constant false alarm rate (CFAR) methods are generally applied for the target detection after clutter mitigation in the through-wall sensing applications using ultra-wide band through-wall radar. Current studies of CFAR only focus on detection of moving human targets without considering the effect of residual clutters. However, in the cases with the presence of strong stationary clutters, little residual clutters after clutter mitigation are strong enough to cause false alarms in the following target detection, compared with the weak human target echoes. Unfortunately, conventional CFAR methods fail to remove the effect of residual clutters and suffer from false alarms. To combat this problem and obtain a reliable detection performance, a moving target CFAR detection method along slow-time profile is proposed in this paper. Experiments with an impulse through wall radar show that the proposed method not only has good detection performance for moving human targets, but also successfully gets rid of the problems brought by the strong residual stationary clutters.
    Ultra-Wideband (ICUWB), 2013 IEEE International Conference on; 01/2013