Publications by authors named "Xiaoji Zhou"

16 Publications

  • Page 1 of 1

Anticorrosion Performance of PVDF Membranes Modified by Blending PTFE Nanoemulsion and Prepared through Usual Non-Solvent-Induced Phase Inversion Method.

Membranes (Basel) 2021 May 31;11(6). Epub 2021 May 31.

Center for Separation and Purification Materials & Technologies, Suzhou University of Science and Technology, Suzhou 215009, China.

In this study, PVDF/PTFE composite membranes were prepared by adding a PTFE nanoemulsion to a PVDF solution and casting it through the conventional non-solvent-induced phase separation method. The objective was to explore the effectiveness of using a simple and economical method to modify PVDF membranes with PTFE to enhance their anticorrosion performance, especially under highly acidic or alkaline conditions. PTFE nanoparticles (of around 200 nm in size) in nanoemulsion form were blended with PVDF at a mass ratio of PTFE:PVDF in the range of 0-0.3:1. The obtained membranes were examined to determine the effect of the added PTFE nanoparticles on the structure of the modified PVDF membranes as well as on their mechanical strength and surface characteristics. The membranes were then immersed in various concentrations of acidic or alkaline solutions for varied durations ranging from a few days up to as long as 180 days (6 months). The impacts of by the corrosive solutions on the tensile strength, surface roughness, and water flux of the membranes with different exposure times were quantified. The results showed that although a certain extent of change may occur with extended immersion times, greatly enhanced anticorrosion performance was obtained with the prepared PVDF/PTFE membranes compared with the unmodified PVDF membrane. For example, after being immersed in 5 mol-H·L HSO, HCl, and HNO solutions for 6 months, the tensile strength at breaking point remained at up to 69.70, 74.07, and 71.38%, respectively, of the initial strength for the PVDF/PTFE (M30) membrane. This was in contrast to values of only 55.77, 70.43, and 61.78% for the unmodified PVDF membrane (M0). Although the water flux and surface roughness showed a change trends to the tensile strength, the PVDF/PTFE (M30) membrane had much higher stability than the PVDF (M0) membrane. In a continuous filtration experiment containing HSO at 0.01 mol-H·L for 336 h (14 days), the PVDF/PTFE membrane showed a maximum flux change of less than 30%. This was in comparison with a change of up to 50% for the PVDF membrane. However, the PVDF/PTFE membranes did not seem to have a greatly enhanced anticorrosion performance in the alkaline solution environment tested.
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http://dx.doi.org/10.3390/membranes11060420DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8228311PMC
May 2021

Evidence of Potts-Nematic Superfluidity in a Hexagonal sp^{2} Optical Lattice.

Phys Rev Lett 2021 Jan;126(3):035301

State Key Laboratory of Surface Physics, Institute of Nanoelectronics and Quantum Computing, Department of Physics, Fudan University, Shanghai 200438, China.

As in between liquid and crystal phases lies a nematic liquid crystal, which breaks rotation with preservation of translation symmetry, there is a nematic superfluid phase bridging a superfluid and a supersolid. The nematic order also emerges in interacting electrons and has been found to largely intertwine with multiorbital correlation in high-temperature superconductivity, where Ising nematicity arises from a four-fold rotation symmetry C_{4} broken down to C_{2}. Here, we report an observation of a three-state (Z_{3}) quantum nematic order, dubbed "Potts-nematicity", in a system of cold atoms loaded in an excited band of a hexagonal optical lattice described by an sp^{2}-orbital hybridized model. This Potts-nematic quantum state spontaneously breaks a three-fold rotation symmetry of the lattice, qualitatively distinct from the Ising nematicity. Our field theory analysis shows that the Potts-nematic order is stabilized by intricate renormalization effects enabled by strong interorbital mixing present in the hexagonal lattice. This discovery paves a way to investigate quantum vestigial orders in multiorbital atomic superfluids.
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http://dx.doi.org/10.1103/PhysRevLett.126.035301DOI Listing
January 2021

Asymmetric population of momentum distribution by quasi-periodically driving a triangular optical lattice.

Opt Express 2019 Sep;27(20):27786-27796

Ultracold atoms in periodical-driven optical lattices enable us to investigate novel band structures and explore the topology of the bands. In this work, we investigate the impact of the ramping process of the driving signal and propose a simple but effective method to realize desired asymmetric population in momentum distribution by controlling the initial phase of the driving signal. A quasi-momentum oscillation along the shaking direction in the frame of reference co-moving with the lattice is formed, causing the formation of the mix of ground energy band and first excited band in laboratory frame, within the regime that the driving frequency is far less than the coupling frequency between ground band and higher energy bands. This method avoids the construction of intricate lattices or complex control sequence. With a triangular lattice, we experimentally investigate the influence of the initial phase, frequency, amplitude of the driving signal on the population difference and observe good agreement with our theoretical model. This provides guidance on how to load a driving signal in driven optical lattice experiment and also potentially supplies a useful tool to form a qubit that can be used in quantum computation.
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http://dx.doi.org/10.1364/OE.27.027786DOI Listing
September 2019

Facile Synthesis of Thiol-Functionalized Magnetic Activated Carbon and Application for the Removal of Mercury(II) from Aqueous Solution.

ACS Omega 2019 May 15;4(5):8568-8579. Epub 2019 May 15.

Center for Separation and Purification Materials & Technologies and Jiangsu Provincial Key Laboratory of Environmental Science and Engineering, Suzhou University of Science and Technology, Suzhou 215009, China.

To improve the adsorption capacity, reduce the disposal cost, and enhance the separation efficiency of common activated carbon as an adsorbent in wastewater treatment, a novel thiol-modified magnetic activated carbon adsorbent of NiFeO-PAC-SH was successfully synthesized with a facile and safe hydrothermal method without any toxic and harmful reaction media. The as-prepared NiFeO-PAC-SH can effectively remove mercury(II) ions from aqueous solution. The maximal adsorption capacities from the experiment and Langmuir fitting achieve 298.8 and 366.3 mg/g at pH 7, respectively, exceeding most of adsorptive materials. The as-prepared NiFeO-PAC-SH has an outstanding regeneration performance, remarkable hydrothermal stability, and efficient separation efficiency. The data of kinetics, isotherms, and thermodynamics show that the adsorption of mercury(II) ions is spontaneous and exothermic. Ion exchange and electrostatic attraction are the main adsorption factors. The experimental results exhibit that the NiFeO-PAC-SH can be a prominent substitute for conventional activated carbon as an adsorbent.
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http://dx.doi.org/10.1021/acsomega.9b00572DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6648564PMC
May 2019

Enhancing the Antifouling Properties of Poly(vinylidene fluoride) (PVDF) Membrane through a Novel Blending and Surface-Grafting Modification Approach.

ACS Omega 2018 Dec 14;3(12):17403-17415. Epub 2018 Dec 14.

Center for Separation and Purification Materials & Technologies, Suzhou University of Science and Technology, 1 Kerui Road, 215009 Suzhou, China.

In this study, poly(vinylidene fluoride) (PVDF) membrane was modified through a novel approach by first blending an active component (poly(vinylidene fluoride--chlorotrifluoroethylene), P(VDF--CTFE)) with the PVDF base material, followed by surface grafting of the membrane on the active component to obtain a triblock copolymer functional structure. The prepared membranes were characterized by various analyses, including Fourier-transform infrared, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscope, and filtration tests. It was found that the modified membrane surface showed a much better hydrophilicity (water contact angle of 67.3°) and oleophobicity (oil contact angle of 129.7°). The modification reduced the average surface pore size (from 0.1495 to 0.1072 μm) and thus lowered the pure water flux (from 364.0 to 224.6 L m h at 0.10 MPa of transmembrane pressure), but significantly increased the relative flux recovery (RFR) and the retention efficiency of the modified membrane during the filtration of bovine serum albumin solution and oil/water emulsion. For example, the modified membranes showed 98.6% oil retention (at feed concentration of 0.4 g L), 92.7% RFR by simple water flushing after filtration, and a consistently high oil removal of 96% or above during a five-cycle-continuous filtration test, as compared to 30.4% oil retention and 51.8% RFR for unmodified PVDF/P(VDF--CTFE) blend membrane.
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http://dx.doi.org/10.1021/acsomega.8b02569DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6644313PMC
December 2018

Extraction and identification of noise patterns for ultracold atoms in an optical lattice.

Opt Express 2019 Apr;27(9):12710-12722

To extract useful information about quantum effects in cold atom experiments, one central task is to identify the intrinsic fluctuations from extrinsic system noises of various kinds. As a data processing method, principal component analysis can decompose fluctuations in experimental data into eigenmodes, and give a chance to separate noises originated from different physical sources. In this paper, we demonstrate for Bose-Einstein condensates in one-dimensional optical lattices that the principal component analysis can be applied to time-of-flight images to successfully separate and identify noises from different origins of leading contribution, and can help to reduce or even eliminate noises via corresponding data processing procedures. The attribution of noise modes to their physical origins is also confirmed by numerical analysis within a mean-field theory. As the method does not rely on any a priori knowledge of the system properties, it is potentially applicable to the study of other quantum states and quantum critical regions.
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http://dx.doi.org/10.1364/OE.27.012710DOI Listing
April 2019

Observation of a Dynamical Sliding Phase Superfluid with P-Band Bosons.

Phys Rev Lett 2018 Dec;121(26):265301

School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, China.

Sliding phases have been long sought after in the context of coupled XY models, as they are of relevance to various many-body systems such as layered superconductors, freestanding liquid-crystal films, and cationic lipid-DNA complexes. Here we report an observation of a dynamical sliding phase superfluid that emerges in a nonequilibrium setting from the quantum dynamics of a three-dimensional ultracold atomic gas loaded into the P band of a one-dimensional optical lattice. A shortcut loading method is used to transfer atoms into the P band at zero quasimomentum within a very short time duration. The system can be viewed as a series of "pancake"-shaped atomic samples. For this far-out-of-equilibrium system, we find an intermediate time window with a lifetime around tens of milliseconds, where the atomic ensemble exhibits robust superfluid phase coherence in the pancake directions, but no coherence in the lattice direction, which implies a dynamical sliding phase superfluid. The emergence of the sliding phase is attributed to a mechanism of cross-dimensional energy transfer in our proposed phenomenological theory, which is consistent with experimental measurements. This experiment potentially opens up a novel venue to search for exotic dynamical phases by creating high-band excitations in optical lattices.
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http://dx.doi.org/10.1103/PhysRevLett.121.265301DOI Listing
December 2018

High precision calibration of optical lattice depth based on multiple pulses Kapitza-Dirac diffraction.

Opt Express 2018 Jun;26(13):16726-16735

The precise calibration of optical lattice depth is an important step in the experiments of ultracold atoms in optical lattices. The Raman-Nath diffraction method, as the most commonly used method of calibrating optical lattice depth, has a limited range of validity and the calibration accuracy is not high enough. Based on multiple pulses Kapitza-Dirac diffraction, we propose and demonstrate a new calibration method by measuring the fully transfer fidelity of the first diffraction order. The high sensitivity of the transfer fidelity to the lattice depth ensures the highly precision calibration of the optical lattice depth. For each lattice depth measured, the calibration uncertainty is further reduced to less than 0.6% by applying the Back-Propagation Neural Network Algorithm. The accuracy of this method is almost one order of magnitude higher than that of the Raman-Nath diffraction method, and it has a wide range of validity applicable to both shallow lattices and deep lattices.
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http://dx.doi.org/10.1364/OE.26.016726DOI Listing
June 2018

Excitation of atoms in an optical lattice driven by polychromatic amplitude modulation.

Opt Express 2015 Apr;23(8):10064-74

We investigate the mutiphoton process between different Bloch states in an amplitude modulated optical lattice. In the experiment, we perform the modulation with more than one frequency components, which includes a high degree of freedom and provides a flexible way to coherently control quantum states. Based on the study of single frequency modulation, we investigate the collaborative effect of different frequency components in two aspects. Through double frequency modulations, the spectrums of excitation rates for different lattice depths are measured. Moreover, interference between two separated excitation paths is shown, emphasizing the influence of modulation phases when two modulation frequencies are commensurate. Finally, we demonstrate the application of the double frequency modulation to design a large-momentum-transfer beam splitter. The beam splitter is easy in practice and would not introduce phase shift between two arms.
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http://dx.doi.org/10.1364/OE.23.010064DOI Listing
April 2015

Cyclic amphiphilic random copolymers bearing azobenzene side chains: facile synthesis and topological effects on self-assembly and photoisomerization.

Macromol Rapid Commun 2014 May 13;35(9):901-7. Epub 2014 Mar 13.

Jiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou, 215123, P. R. China.

In this article, well-defined cyclic amphiphilic random copolymers bearing azobenzene side chains and pendent carboxyl moieties, cyclic-P(BHMEm -co-AAn )s, are synthesized by combining atom transfer radical polymerization (ATRP) with Cu(I)-catalyzed azide/alkyne cycloaddition (CuAAC) "click" reaction and selective hydrolysis of tert-butyl ester. Successful synthesis of the cyclic-P(BHMEm -co-AAn )s is fully characterized and verified via conventional gel permeation chromatography, triple detection gel permeation chromatography, nuclear magnetic resonance, Fourier transform infrared, and matrix-assisted laser desorption ionization-time-of-flight mass spectrometry. The cyclic topology induces profound effects on the glass transition temperatures, self-assembly behavior, and photoresponsive performance of the copolymers compared with their linear counterparts.
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http://dx.doi.org/10.1002/marc.201300913DOI Listing
May 2014

The diameters and number of nerve fibers in spinal nerve roots.

J Spinal Cord Med 2015 Jul 7;38(4):532-7. Epub 2014 Mar 7.

Objective: To investigate the anatomical and histological features of spinal nerve roots and provide base data for neuroanastomosis therapy for paraplegia.

Methods: Spinal nerve roots from C1 to S5 were exposed on six adult cadavers. The diameter and the number of nerve fibers of each nerve root were measured, respectively, with a caliper and image analysis software.

Results: As for ventral roots, the diameter of C5 (2.50 ± 0.55 mm) was the largest in cervical segments. In thoracic and lumbosacral segments, the diameter gradually increased from T11 to S1 and then decreased from S1 to S5 except L3. S1 (1.43 ± 0.16 mm) was the thickest root and S5 (0.14 ± 0.02 mm) was the thinnest one. As for dorsal roots, the diameter of C7 (4.61 ± 0.87 mm) was the largest in cervical segments. From T11 to S1, the diameter increased and then decreased gradually from S1 to S5. The diameter of dorsal roots from T1 to S5 was largest at S1 (2.95 ± 0.57 mm) and smallest at S5 (0.27 ± 0.13 mm), respectively. C7 (8467 ± 1019), T12 (6538 ± 892), L3 (9169 ± 1160), and S1 (8253 ± 1419) ventral roots contained the most nerve fibers in cervical, thoracic, lumbar, and sacral segments, respectively. Similarly, C7 (39 653 ± 8458), T1 (26 507 ± 7617), L5 (34 455 ± 2740), and S1 (41 543 ± 3036) dorsal roots, respectively, contained the most nerve fibers in their corresponding segments.

Conclusion: The findings in the current study provided the imperative data and may be valuable for spinal nerve root microanastomosis surgery in the paraplegic patients.
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http://dx.doi.org/10.1179/1079026814Z.000000000273DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4612209PMC
July 2015

Extradural nerve anastomosis technique for bladder reinnervation in spinal cord injury: anatomical feasibility study in human cadavers.

Spine (Phila Pa 1976) 2014 Apr;39(8):635-41

*Department of Orthopedics, the First Affiliated Hospital of Nanjing Medical University, Nanjing, Jiangsu Province, China †Department of Orthopedics, the People's Hospital of Suqian, Drum Tower Hospital Group of Nanjing, Jiangsu Province, China; and ‡Department of Physiology, Nanjing Medical University, Nanjing, Jiangsu Province, China.

Study Design: An anatomic study of extradural spinal root in 9 embalmed cadavers.

Objective: To ascertain the anatomical parameters of the extradural spinal root and to demonstrate the feasibility of spinal root anastomoses without opening the spinal dura mater.

Summary Of Background Data: Intradural anastomosis of the spinal root has made breakthrough progress in treating neurogenic bladder in spinal cord injury. However, because of the complex surgical procedures and extensive bony destruction, its clinical use is not widely promoted.

Methods: Nine formalin-fixed cadavers were used. The distance between the nerve root outlet and ganglion center, the neighboring nerve root-outlet distance, and the gross anatomy of the extradural spinal root were measured with a surgical microscope. The number of nerve fibers from the T7 to S4 ventral roots (VRs) was calculated by immunohistochemical staining.

Results: The longest and shortest lengths of the extradural spinal root were observed at the S4 and T7 levels, with average values of 33.29 and 6.06 mm, respectively. The longest distance between the adjacent nerve root outlets was observed at L1-L2 (mean, 29.16 mm), and shortest at S3-S4 (mean, 11.79 mm). After leaving the dural sac, the spinal root descends in the spinal canal until reaching the corresponding intervertebral foramina, and the motor nerve roots still lie ventrally to the sensory nerve roots. The largest and smallest numbers of nerve fibers were observed at the L3 and S4 levels (mean, 9169 and 1356, respectively).

Conclusion: The dorsal roots and VRs can both be successfully harvested and identified outside the dural sac. The S1 VR can be anastomosed to the S2 VR extradurally without nerve grafts. For extradural neuroanastomosis of the thoracic VRs to the S2 VR, a nerve graft is required. In addition, there are a sufficient number of nerve fibers for functional bladder recovery at the T7-T12 and S1 levels. This study supports the feasibility of extradural spinal root anastomosis as a modified surgical method for treating neurogenic bladder.

Level Of Evidence: N/A.
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http://dx.doi.org/10.1097/BRS.0000000000000208DOI Listing
April 2014

Asymmetric superradiant scattering and abnormal mode amplification induced by atomic density distortion.

Opt Express 2013 Jun;21(12):14377-87

School of Electronics Engineering & Computer Science, Peking University, Beijing 100871, China.

The superradiant Rayleigh scattering using a pump laser incident along the short axis of a Bose-Einstein condensate with a density distortion is studied, where the distortion is formed by shocking the condensate utilizing the residual magnetic force after the switching-off of the trapping potential. We find that very small variation of the atomic density distribution would induce remarkable asymmetrically populated scattering modes by the matter-wave superradiance with long time pulse. The optical field in the diluter region of the atomic cloud is more greatly amplified, which is not an ordinary mode amplification with the previous cognition. Our numerical simulations with the density envelop distortion are consistent with the experimental results. This supplies a useful method to reflect the geometric symmetries of the atomic density profile by the superradiance scattering.
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http://dx.doi.org/10.1364/OE.21.014377DOI Listing
June 2013

Detection of saturated absorption spectroscopy at high sensitivity with displaced crossovers.

Opt Lett 2011 Feb;36(4):561-3

Institute of Quantum Electronics, School of Electronics Engineering Computer Science, Peking University, Beijing, China.

We present an unconventional experimental approach for detecting saturated absorption spectroscopy. Using this approach, crossover peaks are displaced, leaving out peaks corresponding to an atom's natural resonant frequencies. Sensitivity of detection can also be enhanced. Consequently, the spectrum could reflect the energy structure of atoms more explicitly. Without harmful influence from crossovers, the locking range of the error signal is significantly increased and the symmetry of the dispersion line shape is perfectly preserved, so reliability of frequency stabilization can be improved.
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http://dx.doi.org/10.1364/OL.36.000561DOI Listing
February 2011

Observation of a red-blue detuning asymmetry in matter-wave superradiance.

Phys Rev Lett 2010 Nov 23;105(22):220404. Epub 2010 Nov 23.

Physics Laboratory, National Institute of Standards & Technology, Gaithersburg, MD 20899, USA.

We report the first experimental observation of strong suppression of matter-wave superradiance using blue-detuned pump light and demonstrate a pump-laser detuning asymmetry in the collective atomic recoil motion. In contrast to all previous theoretical frameworks, which predict that the process should be symmetric with respect to the sign of the detuning of the pump laser from the one-photon resonance, we find that for condensates the symmetry is broken. With high condensate densities and red-detuned pump light the distinctive multiorder, matter-wave scattering pattern is clearly visible, whereas with blue-detuned pump light superradiance is strongly suppressed. However, in the limit of a dilute atomic gas symmetry is restored.
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http://dx.doi.org/10.1103/PhysRevLett.105.220404DOI Listing
November 2010

Detecting quantum coherence of Bose gases in optical lattices by scattering light intensity in cavity.

Opt Express 2010 Jul;18(15):15664-71

School of Electronics Engineering & Computer Science, Peking University, Beijing 100871, China.

We propose a new method of detecting quantum coherence of a Bose gas trapped in a one-dimensional optical lattice by measuring the light intensity from Raman scattering in cavity. After pump and displacement process, the intensity or amplitude of scattering light is different for different quantum states of a Bose gas, such as superfluid and Mott-Insulator states. This method can also be useful to detect quantum states of atoms with two components in an optical lattice.
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http://dx.doi.org/10.1364/OE.18.015664DOI Listing
July 2010
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